Статті в журналах: "VOLTAGE LIMIT"

1

Schultis, Daniel-Leon, and Albana Ilo. "Increasing the Utilization of Existing Infrastructures by Using the Newly Introduced Boundary Voltage Limits." Energies 14, no. 16 (August 19, 2021): 5106. http://dx.doi.org/10.3390/en14165106.

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The increasing share of distributed generation aggravates voltage limit compliance at customers’ delivery points. Currently, grid operators validate compliance with the voltage limits specified in Grid Codes by conducting load flow simulations at the medium voltage level, considering the connected low voltage grids as ‘loads’ to reduce the modeling effort. This approach does not support the accurate validation of limit compliance, as the voltage drops at the low voltage level are unknown. Nevertheless, to guarantee acceptable voltages even under worst-case conditions, safety margins are involved that impair the utilization of the electricity infrastructure. This study conducts load flows simulations in a test distribution grid, revealing the variable character of the voltage limits at different system boundaries. The conventional load model is extended by new parameters—the boundary voltage limits—to enable the consideration of variable voltage limits in load flow analysis of LINK-based smart grids. The standardized structure of the LINK-architecture allows for the systematic and accurate validation of voltage limit compliance by reducing the required modeling data to the technically necessary minimum. Use cases are specified that allows smart grids to increase the utilization of the electricity infrastructure by day-ahead scheduling and short-term adaptation of boundary voltage limits.

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2

Myklebust, Robert L., Charles E. Fiori, and Dale E. Newbury. "A robust method for determining the Duane-Hunt energy limit from EDS." Proceedings, annual meeting, Electron Microscopy Society of America 48, no. 2 (August 12, 1990): 210–11. http://dx.doi.org/10.1017/s042482010013465x.

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The electron beam energy is a parameter required for quantitative electron probe microanalysis. In fact, it occurs in all parts of the ZAF type matrix correction procedure as well as in all of the other matrix correction procedures. Recently, there has been much interest in analyzing materials using lower beam voltages. Since the correction procedures use the so called “overvoltage” term (beam energy/excitation energy), uncertainties in the beam voltage will generate larger errors than when high beam voltages are used. The user may well be faced with an instrument that does not have a very precise voltmeter to measure the beam voltage, or the reported voltage may not actually represent the potential drop from the filament to ground (specimen). The true beam energy may differ from the “measured” potential drop by several hundred volts.It is difficult and potentially exciting to measure the beam voltage with a calibrated voltmeter; however, we have a built-in method available in the energy-dispersive x-ray detector.

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3

Anichebe, I. B., and A. O. Ekwue. "Improvement of bus voltage profiles of Nigerian power network in the presence of Static Synchronous Compensator (STATCOM) and Doubly Fed Induction Generator (DFIG)." Nigerian Journal of Technology 39, no. 1 (April 3, 2020): 228–37. http://dx.doi.org/10.4314/njt.v39i1.26.

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Frequent blackouts and unstable supply of electricity show that the voltage instability problem has been one of the major challenges facing the power system network in Nigeria. This study investigates the voltage stability analysis of the Nigerian power network in the presence of renewable energy sources; FACTS device is used as a voltage controller. A 330kV, 28-bus power system network was studied using the PSS/E software-based Newton-Raphson load-flow technique. The results show that 10 out of the 28 buses had voltages lying below the statutory limit of 0.95 ≤ 1.05 p.u. The application of STATCOM and DFIG devices on two of the weakest buses restored the voltages to acceptable statutory limits. The total active and reactive power losses were reduced to 18.76% and 18.82% respectively. Keywords: Voltage stability analysis; Integration of renewable energy sources; FACTS controllers, Reactive Power, Power Flow.

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4

Agarwal, Sapan, and Eli Yablonovitch. "Fundamental Conductance \(\div \) Voltage Limit in Low Voltage Tunnel Switches." IEEE Electron Device Letters 35, no. 10 (October 2014): 1061–62. http://dx.doi.org/10.1109/led.2014.2350434.

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5

Yonekura, Daisuke, Huriyzju Fukuda, and Riichi Murakami. "Influence of Deposition Bias Voltage on Fatigue Cracking Behavior of Chromium Nitride Film Deposited on Steel." Key Engineering Materials 353-358 (September 2007): 275–78. http://dx.doi.org/10.4028/www.scientific.net/kem.353-358.275.

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Three point bending fatigue tests were carried out to investigate the influence of bias voltage on fatigue behavior of medium carbon steel with chromium nitride film. The substrate material of the specimens was JIS S45C medium carbon steel. The chromium nitride films were coated at two different bias voltages (VB = -20V, -300V) for fatigue test by arc ion plating method. As a result, the fatigue limit was improved by coating at low bias voltage, while the fatigue limit of high bias voltage samples decreased by coating. In order to clarify the difference between high and low bias voltages, the tensile test was performed using the coated specimens. For this test, the chromium nitride films were deposited at four different bias voltages. It was found the cracking behavior clearly changed between -40V and -80V. For low bias voltage samples, short cracks were initiated in the films, while the long cracks were initiated at same strain for high bias voltage samples. These differences between low and high bias voltage sample may be due to the elastic modulus of the film and droplets distribution in the film.

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6

Alanzi, Sultan Sh, and Rashad M. Kamel. "Photovoltaic Maximum Penetration Limits on Medium Voltage Overhead and Underground Cable Distribution Feeders: A Comparative Study." Energies 14, no. 13 (June 25, 2021): 3843. http://dx.doi.org/10.3390/en14133843.

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This paper investigates the maximum photovoltaic (PV) penetration limits on both overhead lines and underground cables medium voltage radial distribution system. The maximum PV penetration limit is estimated considering both bus voltage limit (1.05 p.u.) and feeder current ampacity (1 p.u.). All factors affect the max PV penetration limit are investigated in detail. Substation voltage, load percentage, load power factor, and power system frequency (50 Hz or 60 Hz) are analyzed. The maximum PV penetration limit associated with overhead lines is usually higher than the value associated with the underground cables for high substation voltage (substation voltage = 1.05 and 1.04 p.u.). The maximum PV penetration limit decreases dramatically with low load percentage for both feeder types but still the overhead lines accept PV plant higher than the underground cables. Conversely, the maximum PV penetration increases with load power factor decreasing and the overhead lines capability for hosting PV plant remains higher than the capability of the underground cables. This paper proved that the capability of the 60-Hz power system for hosting the PV plant is higher than the capability of 50 Hz power system. MATLAB software has been employed to obtain all results in this paper. The Newton-Raphson iterative method was the used method to solve the power flow of the investigated systems.

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7

Kim, Ryu, Ko, and Kim. "Optimal Operation Strategy of ESS for EV Charging Infrastructure for Voltage Stabilization in a Secondary Feeder of a Distribution System." Energies 13, no. 1 (January 1, 2020): 179. http://dx.doi.org/10.3390/en13010179.

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The introduction of electrical vehicle charging infrastructure including electric vehicle (EV) charger renewable energy resource at the secondary feeder in a distribution system has been increased as one of countermeasure for global environmental issues. However, the electric vehicle charging (EVC) infrastructure may act as the peak load in the distribution system, which can adversely impact on the voltage stability when the electric vehicle is quickly charged. Therefore, to keep within the limit capacity of a secondary feeder and allowable limit for the feeder voltage, this paper proposes a stabilization method by an energy storage system (ESS) control strategy at the secondary feeder to not exceed the upper limit or fall below the lower limit. In addition, this paper presents an estimation method to keep the proper standard value of the state of charge (SOC). From the simulation results, the voltage stabilization operation by the ESS should make the feeder voltages of the distribution system (secondary feeder) introduced EVC infrastructure keep better voltage conditions. In addition, the estimation method was able to keep the proper standard value confirming that the SOC of the ESS when it is in standby can be kept within the proper reference range. Therefore, it is confirmed that this strategy is an effective tool to solve the voltage problems by ESS.

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8

Bo Zhai, D. Blaauw, D. Sylvester, and K. Flautner. "The limit of dynamic voltage scaling and insomniac dynamic voltage scaling." IEEE Transactions on Very Large Scale Integration (VLSI) Systems 13, no. 11 (November 2005): 1239–52. http://dx.doi.org/10.1109/tvlsi.2005.859588.

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9

Ogunboyo, Patrick Taiwo, Remy Tiako, and Innocent E. Davidson. "Investigation of Voltage Unbalance Profile in Low Voltage Electrical Distribution Network with Normal Mode Operation Using MATLAB." International Journal of Engineering Research in Africa 35 (March 2018): 60–76. http://dx.doi.org/10.4028/www.scientific.net/jera.35.60.

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With ever increasing use of semiconductor devices and information technology (ICT) equipment in the industry, homes and offices, power quality is gaining attention to both industry and the electric utility. Power voltage quality cause huge economic losses to businesses all over the world. It is estimated to cost industry and commerce about €100 billion per annum in European Union, since voltage quality problem is one of the major power quality disturbances. This paper presents an investigative a study of the 11/0.4 kV, low voltage electrical distribution network and analyzes voltage unbalance. It recommends an effective method of improving the voltage profile and reducing the voltage unbalance to acceptable standard. The network was modelled using distribution network standard parameters for low voltage distribution network using MATLAB/Simulink sim power system tool box. The simulation results show that the percentage voltage unbalance, correct voltage profile and minimum voltage drop of 0.5 km distribution feeder line is of standard acceptable statutory limit, hence the distribution line operates at optimum performance. However, it is also established that the voltage profile for distribution network feeder lengths of 0.8 km to 5 km for balanced and unbalanced distribution lines from the beginning to the customer terminal of the distribution lengths are less than the acceptable allowable limit of – 5 %, of the nominal voltage value, hence voltages are inadmissible for customers use. Moreso, the percentage voltage unbalance, voltage profile and voltage drop on 0.8 km to 5 km distribution feeder line are all less than standard acceptable statutory limit, hence the distribution line operates below optimum performance. It was established that mitigating these problems require the electricity distribution company to install an effective voltage boosting devices along the network lengths in order provide admissible, permissible and normalize end users standard acceptable voltage.

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10

Berthiaume, R. "Voltage limit: processor lives depend on it." Electronics Systems and Software 2, no. 2 (April 1, 2004): 28–32. http://dx.doi.org/10.1049/ess:20040205.

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11

Wang, Xiangdong, Lei Wang, Wenfa Kang, Tiecheng Li, Hao Zhou, Xuekai Hu, and Kai Sun. "Distributed Nodal Voltage Regulation Method for Low-Voltage Distribution Networks by Sharing PV System Reactive Power." Energies 16, no. 1 (December 28, 2022): 357. http://dx.doi.org/10.3390/en16010357.

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With the intensive integration of photovoltaic (PV) sources into the low-voltage distribution networks (LVDN), the nodal voltage limit violations and fluctuation problem cause concerns on the safety operation of a power system. The intermittent, stochastic, and fluctuating characteristics of PV output power leads to the frequent and fast fluctuation of nodal voltages. To address the voltage limit violation and fluctuation problem, this paper proposes a distributed nodal voltage regulation method based on photovoltaic reactive power and on-load tap changer transformers (OLTC). Using the local Q/V (Volt/Var) feedback controller derived from the grid sensitivity matrix, the voltage magnitude information is adopted to adjust the output of PV systems. Moreover, in order to share the burden of voltage regulation among distributed PV systems, a weighted distributed reactive power sharing algorithm is designed to achieve the voltage regulation according to the rated reactive power. Theoretical analysis is provided to show the convergence of the proposed algorithm. Additionally, the coordination strategy for distributed PV systems and OLTC is provided to reduce the reactive power outputs of PV systems. Five simulation case studies are designed to show the effectiveness of the proposed voltage regulation strategy, where the voltage regulation and proportional reactive power sharing can be achieved simultaneously.

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12

Xie, Shijun, Zhou Mu, Weidong Ding, Zhenbo Wan, Shaochun Su, Chenmeng Zhang, Yu Zhang, Yalong Xia, and Donghui Luo. "Development of Broadband Resistive–Capacitive Parallel–Connection Voltage Divider for Transient Voltage Monitoring." Energies 15, no. 2 (January 10, 2022): 451. http://dx.doi.org/10.3390/en15020451.

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The on-site measurement of transient voltages is of great significance in analyzing the fault cause of power systems and optimizing the insulation coordination of power equipment. Conventional voltage transformers normally have a narrow bandwidth and are unable to accurately measure various transient voltages in power systems. In this paper, a wideband parallel resistive–capacitive voltage divider is developed, which can be used for online monitoring of transient voltages in a 220 kV power grid. The structures of the high-voltage and low-voltage arms were designed. The internal electric field distribution of the high-voltage arm was analyzed. The influence factors and improvement techniques of the upper frequency limit were studied. The parameters of the elements of the divider were determined. The voltage withstand performances and scale factors under lightning impulses and AC and DC voltages, the temperature stabilities of scale factors and the step response and bandwidth of the developed voltage divider were tested. The results show that the deviations of the scale factors under various voltage waveforms and different temperatures ranging from −20 to 40 °C are within 3%. The withstand voltage meets the relevant requirements specified in IEC60071-1-2011. The step response 10~90% rise time is approximately 29 ns, and the 3 dB bandwidth covers the range of DC to 10 MHz.

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13

Bogatov, Nikolai. "Autonomous Broadband Current Meter on a High-Voltage Electrode." Infocommunications and Radio Technologies 6, no. 2 (August 23, 2023): 201–10. http://dx.doi.org/10.29039/2587-9936.2023.06.2.17.

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The design of an autonomous noise-proof current meter on a high-voltage electrode is proposed, based on the use of an annular non-inductive shunt with its axially symmetrical connection to the input of the data acquisition module. The parameters of two design options are calculated: high-frequency, with a frequency band of 0–10 GHz, but with a lower limit of the measured current, and relatively low-frequency, with a band of 0–100 MHz, and a high limit of the measured current.

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14

Raghavendra, P., Ramakrishna S. S. Nuvvula, Polamarasetty P. Kumar, Dattatraya N. Gaonkar, A. Sathoshakumar, and Baseem Khan. "Voltage Profile Analysis in Smart Grids Using Online Estimation Algorithm." Journal of Electrical and Computer Engineering 2022 (October 10, 2022): 1–9. http://dx.doi.org/10.1155/2022/9921724.

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Voltage rise is the main obstacle to prevent the increase of distributed generators (DGs) in low-voltage (LV) distribution grids. In order to maintain the power quality and voltage levels within the tolerance limit, new measurement techniques and intelligent devices along with digital communications should be used for better utilization of the distribution grid. This paper presents a real-time sensor-based online voltage profile estimation technique and coordinated Volt/VAR control in smart grids with distributed generator interconnection. An algorithm is developed for voltage profile estimation using real-time sensor remote terminal unit (RTU) which takes into account topological characteristics, such as radial structure and high R/X ratio, of the smart distribution grid with DG systems. A coordinated operation of multiple generators with on-load tap changing (OLTC) transformer for Volt/VAR control in smart grids has been presented. Direct voltage sensitivity analysis is used to select a single DG system for reactive power support in multi-DG environment. The on-load tap changing transformer is employed for voltage regulation when generators’ reactive power contributions are not enough to regulate the voltages. Simulation results show that the reported method is capable of maintaining voltage levels within the tolerance limit by coordinated operation of DG systems and on-load tap changing transformer.

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15

Abdullah, Norhayati, Shahrul Azlan Azizan, Norriza Mohd Isa, Asmaliza Hashim, Mohd Firdaus Abd Rahman, Sarizah Mohamed Nor, Zainal Jamaluddin, Mohd Muzammil Abd Jalil, and Muhammad Jamal Md Isa. "The Accuracy Check of Peak Voltages of Industrial X-Ray Machine Using Spectrometer System." Advanced Materials Research 1087 (February 2015): 1–5. http://dx.doi.org/10.4028/www.scientific.net/amr.1087.1.

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Measurement of peak voltage of Philips Industrial X-ray Machine is essential to be carried out at least at annual basis to ensure the accuracy of tube voltage applied in determination of standard radiation qualities for calibrating diagnostic dosemeter. In this paper, the peak voltages for dial voltages range within 40kV to 160kV were measured using Amptek spectrometer system. All X-ray spectrums produced from the X-ray tube were calibrated against standard calibration spectrum that was established using two standard sources: 55Fe and 57Co. The peak voltage for each dial voltage was determined based on the end point energy of the X-ray spectrum. The percentage deviation of measured peak voltage relative to dial voltage was calculated. The results from measurement in 2008 to 2013 demonstrate that all peak voltages from 40kV to 160kV tube potentials are within the tolerance limit of ± 5%. These results complies the recommendation by the International Electrotechnical Commission (IEC) 61676. As a conclusion, regular checks of peak voltage should be performed to ensure consistency of voltage applied to the X-ray tube thus maintain the accuracy of standard radiation qualities produced from the X-ray tube.

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16

Hu, Shu Ju, Ling Ling Wang, and Ya Deng. "Analysis on Power Output Capability and its Power Control Strategy of DFIG Wind Turbine under Unbalanced Grid Voltage." Applied Mechanics and Materials 448-453 (October 2013): 1819–24. http://dx.doi.org/10.4028/www.scientific.net/amm.448-453.1819.

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Wind turbines are required by gird codes that active and reactive power should be fed into power grid during gird faults such as voltage sags. Power output capability is important for DFIG wind turbine to provide active and reactive power support. Constraints of stator, rotor maximum current and maximum output voltage of rotor-side converter (RSC) of DFIG are considered to analyze stator power output limit of the DFIG under unbalanced voltage sags, and newton-raphson method is used to solve the power limits, then the power control strategy based on power limit analysis is proposed. Simulation, calculation and comparison are carried out by a 1.5MW DFIG wind turbine model, and the effectiveness of the analysis and the proposed control strategy is verified.

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17

Liu, Guangmao, Jiangtao Chen, Runrun Li, Jialin Jin, and Yuying Cheng. "Multi-agent technology based voltage grading control method for distribution network." ITM Web of Conferences 47 (2022): 03012. http://dx.doi.org/10.1051/itmconf/20224703012.

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It is one of the challenges to solve the power quality problems such as voltage fluctuation and voltage exceeding limit caused by the largescale grid connection of distributed photovoltaic (DPV). Considering the operation speed of voltage regulation control in distribution network, this paper proposes a voltage hierarchical control method based on multi-agent structure. The mathematical models of this method are divided into dualtime scale global optimization model and event-triggered voltage regional autonomy model, aiming at solving the problem of operation safety of voltage exceeding limit. The method is verified by a specific example. The results show that this method can respond quickly to the change of power grid voltage, and help to reduce the risk of voltage exceeding the limit, and improve the operation economy of distribution network.

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18

McAdams, E. T., and J. Jossinet. "Physical interpretation of Schwan’s limit voltage of linearity." Medical & Biological Engineering & Computing 32, no. 2 (March 1994): 126–30. http://dx.doi.org/10.1007/bf02518908.

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19

Han, Sangwook. "Calculating the Interface Flow Limits for the Expanded Use of High-Voltage Direct Current in Power Systems." Energies 13, no. 11 (June 4, 2020): 2863. http://dx.doi.org/10.3390/en13112863.

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Although loads are increasingly becoming concentrated in metropolitan areas, power generation has decreased in metropolitan areas and increased in nonmetropolitan areas; hence, power transmission must occur through interface lines. To achieve this, additional transmission lines must be secured because the existing interface lines have reached their large-scale power transmission limits. The Korea Electric Power Corporation has installed many high-voltage direct current lines, thereby impacting the determination of interface power flow limits. These serve as the basis for system operations. However, knowledge of operating high-voltage direct current lines as a simple transmission line in a single power system is lacking. The effects of high-voltage direct current and its related parameters for interface flow limit analysis remain unclear. Furthermore, whether high-voltage direct current should be included in the selection of the interface lines that serve as the basis for interface flow remains unclear. In addition, whether the high-voltage direct current line faults should be included in the contingency list for determining the interface flow limits has not been considered. Additionally, it has not been determined whether to operate the DC tap when performing the simulation This study addresses these issues and determines the conditions that are necessary for determining the interface flow limits when a high-voltage direct current transmission facility has been installed in a land power system. The results conclude how to reflect the above conditions reasonably when performing the interface flow limit analysis on a system that includes the HVDC lines.

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20

Seok, Jul-Ki, and SeHwan Kim. "Hexagon Voltage Manipulating Control (HVMC) for AC Motor Drives Operating at Voltage Limit." IEEE Transactions on Industry Applications 51, no. 5 (September 2015): 3829–37. http://dx.doi.org/10.1109/tia.2015.2416125.

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21

Cavraro, Guido, Tommaso Caldognetto, Ruggero Carli, and Paolo Tenti. "A Master/Slave Approach to Power Flow and Overvoltage Control in Low-Voltage Microgrids." Energies 12, no. 14 (July 18, 2019): 2760. http://dx.doi.org/10.3390/en12142760.

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This paper proposes a technique to control distributed energy resources in low-voltage microgrids aiming at (i) allowing power flow control at the point of connection with the upstream grid, (ii) keeping voltage profiles within the operational limits. The first feature is crucial in smart low-voltage power systems. In fact, it enables both demand-responses, which is extremely valuable from the point of view of distribution system operators and for energy trading, and the autonomous operation of the microgrid. The latter can be achieved by regulating to zero the power exchanged with the main grid. The second feature allows to limit voltage increases due to active power injection by distributed energy resources and, thus, to limit stresses on the electrical infrastructure and the served loads, which is a concrete issue as renewables become widely deployed in the low-voltage scenario. The proposed approach is firstly described in detail, then a systematic analysis of its local and global properties is reported. All the obtained results are verified considering the IEEE 37 test feeder in realistic operating conditions.

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22

Kumar, Praveen. "Alternative Criteria of Voltage Stability Margin for the Purpose of Load Shedding." International Journal for Research in Applied Science and Engineering Technology 9, no. 10 (October 31, 2021): 201–6. http://dx.doi.org/10.22214/ijraset.2021.38194.

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Abstract: Voltage instability takes on the form of a dramatic drop of transmission system voltages, which may lead to system disruption. During the past two decades it has become a major threat for the operation of many systems and, in the prevailing open access environment, it is a factor leading to limit power transfers. The objective of this paper is to present new method of under voltage protection with maximum utilization of system capabilities.

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23

Malla, S. G., and C. N. Bhende. "Study of Stand-Alone Microgrid under Condition of Faults on Distribution Line." International Journal of Emerging Electric Power Systems 15, no. 5 (October 1, 2014): 501–12. http://dx.doi.org/10.1515/ijeeps-2013-0142.

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Abstract The behavior of stand-alone microgrid is analyzed under the condition of faults on distribution feeders. During fault since battery is not able to maintain dc-link voltage within limit, the resistive dump load control is presented to do so. An inverter control is proposed to maintain balanced voltages at PCC under the unbalanced load condition and to reduce voltage unbalance factor (VUF) at load points. The proposed inverter control also has facility to protect itself from high fault current. Existing maximum power point tracker (MPPT) algorithm is modified to limit the speed of generator during fault. Extensive simulation results using MATLAB/SIMULINK established that the performance of the controllers is quite satisfactory under different fault conditions as well as unbalanced load conditions.

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24

Saeed, Wafaa, and Layth Tawfeeq. "Voltage Collapse Optimization for the Iraqi Extra High Voltage 400 kV Grid based on Particle Swarm Optimization." Iraqi Journal for Electrical and Electronic Engineering 13, no. 1 (June 1, 2017): 17–31. http://dx.doi.org/10.37917/ijeee.13.1.3.

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The continuously ever-growing demand for the electrical power causing the continuous expansion and complexity of power systems, environmental and economic factors forcing the system to work near the critical limits of stability, so research's stability have become research areas worthy of attention in the resent day. The present work includes two phases: The first one is to determine the Voltage Stability Index for the more insensitive load bus to the voltage collapse in an interconnected power system using fast analyzed method based on separate voltage and current for PQ buses from these of PV buses, while the second phase is to suggested a simulated optimization technique for optimal voltage stability profile all around the power system. The optimization technique is used to adjust the control variables elements: Generator voltage magnitude, active power of PV buses, VAR of shunt capacitor banks and the position of transformers tap with satisfied the limit of the state variables (load voltages, generator reactive power and the active power of the slack bus). These control variables are main effect on the voltage stability profile to reach the peak prospect voltage stable loading with acceptable voltage profile. An optimized voltage collapse based on Particle Swarm Optimization has been tested on both of the IEEE 6 bus system and the Iraqi Extra High Voltage 400 kV Grid 28 bus. To ensure the effectiveness of the optimization technique a comparison between the stability indexes for load buses before and after technical application are presented. Simulation results have been executed using Matlab software.

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25

Ezeruigbo, E. N., A. O. Ekwue, and L. U. Anih. "Voltage Stability Analysis of Nigerian 330kV Power Grid using Static P-V Plots." Nigerian Journal of Technology 40, no. 1 (March 23, 2021): 70–80. http://dx.doi.org/10.4314/njt.v40i1.11.

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Nigeria power system has been experiencing total or partial system failures in recent times and voltage instability is a strong factor. The paper seeks to perform the voltage stability analysis, based on static P-V plots, on buses located around and within the South East zone of Nigeria. An injection group containing generators to serve as the source and a sink group as loads to be monitored are created. The generators are assumed to be within their min/max MW limits. The load is increased in the sink group as well as in the source group to maintain the same generation/load balance. Load power and bus voltages (P-V) curves are plotted on the load busbars and the first busbar to reach the voltage collapse and MW transfer limit are determined. From the results obtained, at a load of 100 MW, Makurdi bus recorded a voltage of 0.9301 pu which is already below the regulatory standards of ±5% of the nominal line voltage. It entered the region of instability at a load of 245 MW. This created a situation of system instability and a possible partial system collapse. Subsequently, at a load of 260 MW, the system clearly entered unstable region giving rise to partial system collapse of the network.

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26

Bakhtiari-Nejad, F., and M. Meidan-Sharafi. "Vibration Optimal Control of a Smart Plate with Input Voltage Constraint of Piezoelectric Actuators." Journal of Vibration and Control 10, no. 12 (December 2004): 1749–74. http://dx.doi.org/10.1177/1077546304042069.

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A nonlinear optimal control of a plate vibration is developed. Three pairs of piezoelectric patches with limited voltages input are used as a source of applying an active forcing function to control the vibration of the plate. The dynamic model of the plate with piezoelectric actuators is applied for the purpose of analyzing the coupling between piezoelectric actuators and a plate. The model is based on discrete assumed mode shapes of different beams. To keep the voltages of any pair of actuators in their allowable limits, the optimal control procedure presented in this paper shows that the voltage of other piezoelectric actuators that are in the allowable limit would also be affected. Therefore, the Pontryogan minimum principle is not enough for systems with multi inequality constrained of control inputs.

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27

Blakiewicz, Grzegorz. "Low-Voltage LDO Regulator Based on Native MOS Transistor with Improved PSR and Fast Response." Energies 16, no. 12 (June 20, 2023): 4825. http://dx.doi.org/10.3390/en16124825.

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In this paper, a low-voltage low-dropout analog regulator (ALDO) based on a native n-channel MOS transistor is proposed. Application of the native transistor with the threshold voltage close to zero allows elimination of the charge pump in low-voltage regulators using the pass element in a common drain configuration. Such a native pass transistor configuration allows simplification of regulator design and improved performance, with supply voltages below 1 V, compared to commonly used regulators with p-channel MOS transistors. In the presented design of ALDO regulator in 180 nm CMOS X-FAB technology, an output voltage of 0.7 V was achieved with an output current of 10 mA and a supply voltage of 0.8 V. Simulation results show that despite the low supply voltage, output voltage spikes do not exceed 70 mV at the worst technology corner when output current transients from 100 µA to 10 mA. Under such conditions, stable operation and power supply rejection PSR = 35 dB were achieved with an output capacitance of 0–500 pF. The proposed regulator allows to push the limit of ALDO regulator applications to voltages below 1 V with only slight degradation of its performance.

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28

Sundaravazhuthi*, V., Dr A. Alli Rani, and M. Manoj Kumar. "Raise Voltage Stability Limit of a Power System using Reactive Power Compensation Technique." International Journal of Innovative Technology and Exploring Engineering 8, no. 12 (October 30, 2019): 2931–34. http://dx.doi.org/10.35940/ijitee.k1752.1081219.

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In recent years, voltage stability problems have been increasing since power systems operate close to stability limits. The voltage stability problem of a power system is associated with a rapid voltage drop due to heavy system load and it occurs because of inadequate reactive power support at some critical bus. One of the serious consequences of the voltage stability is a system blackout, and this has received more attention in recent years. Accurate determination of stability limit and amount of reactive power injection to stabilize is important.This paper proposes to determine voltage stability margin of a critical bus and also provide amount of reactive power injection to the bus particularly during overload, a simple two bus equivalent model of the power system is used to determine the maximum apparent power for different power factors. Any required apparent power can directly obtained by correcting the reactive power at critical bus. Experimental results support our theoretical findings.

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29

Liu, Bing, Ying Wang, Zhen Yang, Yun Wei Li, Hua Zhi Xie, Yan Zhang, Wen Chao Zhang, Xiang Yang Deng, and Cheng Ming He. "Evaluation Method of Voltage Stability Based on Minimum Singular Value." Applied Mechanics and Materials 511-512 (February 2014): 1128–32. http://dx.doi.org/10.4028/www.scientific.net/amm.511-512.1128.

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When the system reaches the static voltage stability limit point, Jacobian matrix is singular. By checking if minimum singular value is zero, its very easy to determine whether or not Jacobian matrix is singular. So the minimum singular value of Jacobian matrix can reflects the degree of system voltage stability effectively. Firstly this paper introduces singular value decomposition, analyses load characteristic and excitation limits involved in this method and examples on PSD-FDS are demonstrated. At last, suggestion on voltage stability monitoring by minimum singular value is proposed.

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30

Chen, Shuhao, Ting Yuan, and Fei Lin. "Research on Reactive Voltage Control of Distribution Network with Distributed Photovoltaic Sources." Journal of Physics: Conference Series 2310, no. 1 (October 1, 2022): 012025. http://dx.doi.org/10.1088/1742-6596/2310/1/012025.

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Abstract Aiming at the problem that the voltage of multiple nodes exceeds the limit after the distributed photovoltaic source is connected, a reactive voltage control method of distribution network is proposed. It modeled the distribution network system with distributed photovoltaic sources, determined the maximum photovoltaic output and adjustable amount, and calculated the power flow. The line loss can be obtained from the node voltage and rated power, and the power distribution of each branch of the whole network can be further obtained. This paper analyzed the influence of photovoltaic power access on the voltage quality of the distribution network from the perspective of power. It calculated the reactive output power of reactive power compensation equipment of upstream and downstream nodes. In this paper, the active power of distributed generation is locally reduced at each out-of-limit node to control the voltage. The experimental results show that the proposed method can effectively improve the relationship between photovoltaic output and voltage, and realize the correction of photovoltaic regulation. Therefore, it can reduce the risk of voltage out of limit and improve the voltage quality.

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31

Avino, F., B. Gaffinet, D. Bommottet, A. Howling, and I. Furno. "Slip Ring Test Assembly With Increased Breakdown Voltage Limit for High-Voltage Bus Satellites." IEEE Aerospace and Electronic Systems Magazine 35, no. 8 (August 1, 2020): 32–36. http://dx.doi.org/10.1109/maes.2020.2993388.

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32

Lu, Yu, Mengdi Fu, Jin Gao, Qingxin Shi, and Wenxia Liu. "Voltage limit violation risk evaluation method considering communication failures in distributed voltage regulation system." International Journal of Electrical Power & Energy Systems 147 (May 2023): 108886. http://dx.doi.org/10.1016/j.ijepes.2022.108886.

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33

Che Mat Haris, Harizan, Ismail Musirin, and Mohamad Fadhil Mohd Kamal. "Maximum Loadability Identification Using Self-Tuning Algorithm Considering Voltage Limit." Applied Mechanics and Materials 785 (August 2015): 393–97. http://dx.doi.org/10.4028/www.scientific.net/amm.785.393.

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Due to the complexity of power system nowadays, voltage limit has become a concerned issue. This phenomenon attracted numerous studies in finding the ultimate solution. This paper presents the development of self-tuning technique for identifying maximum loadability for selected buses in a power system network. The algorithm is able to perform fast process in consideration of the voltage limit between 0.9 p.u. to 1.05 p.u. as the acceptable voltage limit in power system community. The proposed concept is conducted for single and multi-load increment; executed on IEEE 14-Bus RTS and IEEE 26-Bus RTS. The proposed technique is feasible for larger transmission system implementation, which in turn avoid computation burden to power system operators.

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34

Yu, Tian, Jing Yong, and Wilsun Xu. "An Equivalent Voltage Index to Quantify the Impact of Harmonics on Shunt Capacitors." Renewable Energy and Power Quality Journal 21, no. 1 (July 2023): 63–68. http://dx.doi.org/10.24084/repqj21.223.

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Harmonic distortions are known to affect the normal operation and life of power equipment. Shunt capacitor is one piece of equipment that is very sensitive to harmonics. Although limits have been established to limit the harmonic distortions experienced by a capacitor, methods to quantify the harmonic impact with easy-to-understand indices are still at large. This paper aims to address the above gap by proposing an equivalent voltage index. This index is to represent the impact of harmonic voltages and their features (such as peak value) into an equivalent increase in the fundamental frequency voltage otherwise experienced by the capacitor. The main advantage of such an equivalence is that PQ and non-PQ engineers can easily relate the impact to the general capacitor loading concept. The index is especially helpful to understand the impact of harmonics on capacitor and thus to justify harmonic mitigation projects.

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35

Toyoda, Junichi, Be-fei Fang, and Hiroumi Saitoh. "Bifurcation of Voltage Stability Limit in Direct Computational Approach." IEEJ Transactions on Power and Energy 115, no. 6 (1995): 576–81. http://dx.doi.org/10.1541/ieejpes1990.115.6_576.

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36

Pei, Genji, Liyi Li, Xiaonan Gao, Jiaxi Liu, and Ralph Kennel. "Predictive Current Trajectory Control for PMSM at Voltage Limit." IEEE Access 8 (2020): 1670–79. http://dx.doi.org/10.1109/access.2019.2962742.

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37

Pulgar-Painemal, Héctor A., and Ricardo I. Gálvez-Cubillos. "Limit-induced bifurcation by wind farm voltage supervisory control." Electric Power Systems Research 103 (October 2013): 122–28. http://dx.doi.org/10.1016/j.epsr.2013.05.010.

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38

Obadina, O. O., and G. J. Berg. "Determination of voltage stability limit in multimachine power systems." IEEE Transactions on Power Systems 3, no. 4 (1988): 1545–54. http://dx.doi.org/10.1109/59.192964.

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39

Jiang, Fei, Chunming Tu, Qi Guo, Zhikang Shuai, Xi He, and Jiao He. "Dual-Functional Dynamic Voltage Restorer to Limit Fault Current." IEEE Transactions on Industrial Electronics 66, no. 7 (July 2019): 5300–5309. http://dx.doi.org/10.1109/tie.2018.2868254.

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40

Wang, Shuangmei. "Novel current limit value test technology with voltage-mode." Contemporary Engineering Sciences 6 (2013): 403–6. http://dx.doi.org/10.12988/ces.2013.31059.

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41

Ellis, Thomas L., Paulo A. Garcia, John H. Rossmeisl, Natalia Henao-Guerrero, John Robertson, and Rafael V. Davalos. "Nonthermal irreversible electroporation for intracranial surgical applications." Journal of Neurosurgery 114, no. 3 (March 2011): 681–88. http://dx.doi.org/10.3171/2010.5.jns091448.

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Object Nonthermal irreversible electroporation (NTIRE) is a novel, minimally invasive technique to treat cancer, which is unique because of its nonthermal mechanism of tumor ablation. This paper evaluates the safety of an NTIRE procedure to lesion normal canine brain tissue. Methods The NTIRE procedure involved placing electrodes into a targeted area of brain in 3 dogs and delivering a series of short and intense electric pulses. The voltages of the pulses applied were varied between dogs. Another dog was used as a sham control. One additional dog was treated at an extreme voltage to determine the upper safety limits of the procedure. Ultrasonography was used at the time of the procedure to determine if the lesions could be visualized intraoperatively. The volumes of ablated tissue were then estimated on postprocedure MR imaging. Histological brain sections were then analyzed to evaluate the lesions produced. Results The animals tolerated the procedure with no apparent complications except for the animal that was treated at the upper voltage limit. The lesion volume appeared to decrease with decreasing voltage of applied pulses. Histological examination revealed cell death within the treated volume with a submillimeter transition zone between necrotic and normal brain. Conclusions The authors' results reveal that NTIRE at selected voltages can be safely administered in normal canine brain and that the volume of ablated tissue correlates with the voltage of the applied pulses. This preliminary study is the first step toward using NTIRE as a brain cancer treatment.

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42

Chudy, Aleksander, Piotr Hołyszko, and Paweł Mazurek. "Fast Charging of an Electric Bus Fleet and Its Impact on the Power Quality Based on On-Site Measurements." Energies 15, no. 15 (July 30, 2022): 5555. http://dx.doi.org/10.3390/en15155555.

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The subject of this study was a distribution substation that feeds 14 fast DC chargers (80 kW) located at the bus depot in Lublin, Poland. The voltage variations were determined to be within the PN-EN 50160 standard limit values (±10% Un). There were several events registered when 4th, 6th, 8th, and 10th voltage harmonics were above the PN-EN 50160 limit during the charging of the electric buses. The obtained maximum 10 min average values of the total voltage harmonic distortion (THD) were 3.36%, 2.27%, and 2.89% for the first, second, and third phase, respectively, i.e., below the limit value of 8% required by PN-EN 50160. Due to the exceedance of the 6th voltage harmonic, the PN-EN 50160 requirements were not met.

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43

Majeed, Issah Babatunde, and Nnamdi I. Nwulu. "Impact of Reverse Power Flow on Distributed Transformers in a Solar-Photovoltaic-Integrated Low-Voltage Network." Energies 15, no. 23 (December 6, 2022): 9238. http://dx.doi.org/10.3390/en15239238.

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Modern low-voltage distribution systems necessitate solar photovoltaic (PV) penetration. One of the primary concerns with this grid-connected PV system is overloading due to reverse power flow, which degrades the life of distribution transformers. This study investigates transformer overload issues due to reverse power flow in a low-voltage network with high PV penetration. A simulation model of a real urban electricity company in Ghana is investigated against various PV penetration levels by load flows with ETAP software. The impact of reverse power flow on the radial network transformer loadings is examined for high PV penetrations. Using the least squares method, simulation results are modelled in Excel software. Transformer backflow limitations are determined by correlating operating loads with PV penetration. At high PV penetration, the models predict reverse power flow into the transformer. Interpolations from the correlation models show transformer backflow operating limits of 78.04 kVA and 24.77% at the threshold of reverse power flow. These limits correspond to a maximum PV penetration limit of 88.30%. In low-voltage networks with high PV penetration; therefore, planners should consider transformer overload limits caused by reverse power flow, which degrades transformer life. This helps select control schemes near substation transformers to limit reverse power flow.

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44

Rataj, Daniel, Dennis Slawik, Krzysztof Wrobel, and Krzysztof Tomczewski. "A fast switched reluctance motor controller based on FPGA." ITM Web of Conferences 19 (2018): 01028. http://dx.doi.org/10.1051/itmconf/20181901028.

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The paper presents the concept and practical implementation of a switched reluctance motor control system in an FPGA programmable device. The developed control system was designed for testing high-speed motors in order to limit the delays of output signals in relation to the signals from the encoder. The controller enables the values of commutation angles and PWM voltage to be set along with current limit values, measures the values of voltages and currents, and sends the results to the computer to be archived.

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45

Jaroenkiattrai, Jedsada, and Viboon Chunkag. "Voltage Ripple Reduction in Voltage Loop of Voltage Source Converter." International Journal of Power Electronics and Drive Systems (IJPEDS) 8, no. 2 (June 1, 2017): 869. http://dx.doi.org/10.11591/ijpeds.v8.i2.pp869-881.

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In order to achieve a good dynamical response of a full-bridge AC-DC voltage source converters (VSC). The bandwidth of PI controller must be relatively wide. This leads to the voltage ripple produced in the control signal, as known that its ripple frequency has twice of the line frequency and cause the 3rd harmonic of an input current. A Ripple Voltage Estimator (RVE) algorithm and Feed-Forward Compensation (FFC) algorithm are proposed and added to the conventional control. The RVE algorithm estimated the ripple signal to subtract it occurring in the voltage loop. As a result, the 3rd harmonic of the input current can be reduced, and hence the Total Harmonic Distortion of input current (THDi) are improved. In addition, the FFC algorithm will offer a better dynamical response of output voltage. The performance evaluation was conducted through the simulation and experiment at 110Vrms/50Hz of the input voltage, with a 600 W load and 250 V<sub>dc</sub> output voltage. The overall system performances are obtained as follows: the power factor at the full load is higher 0.98, the harmonic distortion at AC input power source of the converter is under control in IEC61000-3-2 class A limit, and the overall efficiency is greater than 85%.

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46

Zhu, Lin, Xiaofang Meng, Lidi Wang, Nannan Zhang, and Hui Wang. "Voltage Control Strategy for Low-Voltage Distribution Network with Distributed Energy Storage Participating in Regulation under Low-Carbon Background." Sustainability 15, no. 13 (June 22, 2023): 9943. http://dx.doi.org/10.3390/su15139943.

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With the gradual advancement towards the goal of carbon neutrality, photovoltaic power generation, as a relatively mature zero-carbon power technology, will be connected to the grid in an increasing proportion. A voltage control strategy, involving distributed energy storage, is proposed in order to solve the voltage deviation problem caused by the high proportion of PV connected to the low voltage distribution network (LVDN). A voltage calculation method of the LVDN node with a high proportion of PV is proposed. According to the voltage distribution of the LVDN nodes running throughout the day, fuzzy cluster analysis was used to partition the nodes in the LVDN. A two-objective mathematical model for optimizing distributed energy storage in a partition was constructed, and a particle swarm optimization algorithm was used to solve the model. A voltage control strategy based on sensitivity analysis is proposed, and a mathematical model is established to analyze the relationship between the node current increment and the node off-limit voltage. The mathematical relationship among the node off-limit voltage, node off-limit power and energy storage exchange power is derived, and the voltage deviation of the distribution network can be suppressed by adjusting the injected power of the distributed energy storage. Through case analysis, it is verified that the proposed voltage control strategy can reduce the voltage deviation of the distribution network nodes, effectively solve the problem of the distribution network voltage deviation, and reduce the active power loss.

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47

Blaauwbroek, Niels, Phuong Nguyen, and Han Slootweg. "Data-Driven Risk Analysis for Probabilistic Three-Phase Grid-Supportive Demand Side Management." Energies 11, no. 10 (September 21, 2018): 2514. http://dx.doi.org/10.3390/en11102514.

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Along with the emerging development of demand side management applications, it is still a challenge to exploit flexibility realistically to resolve or prevent specific geographical network issues due to limited situational awareness of the (unbalanced low-voltage) network as well as complex time dependent constraints. To overcome these problems, this paper presents a time-horizon three-phase grid-supportive demand side management methodology for low voltage networks by using a universal interface that is established between the demand side management application and the monitoring and network analysis tools of the network operator. Using time-horizon predictions of the system states that the probability of operational limit violations is identified. Since this analysis is computationally intensive, a data driven approach is adopted by using machine learning. Time-horizon flexibility is procured, which effectively prevents operation limit violation from occurring independent of the objective that the demand side management application has. A practical example featuring fair power sharing demonstrates the effectiveness of the presented method for resolving over-voltages and under-voltages. This is followed by conclusions and recommendations for future work.

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48

Demchenko, D., N. Rubcova, V. Ryabchenko, and A. Tokarskiy. "Distribution of Currents and Voltages, Induced by Electric Field of Three-Phase Overhead Transmission Line along the Grounded Phase/Cable of Disconnected Parallel Power Line." Safety in Technosphere 9, no. 1 (October 13, 2020): 31–40. http://dx.doi.org/10.12737/1998-071x-2020-31-40.

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The health maintenance of linemen working at overhead transmission lines under induced voltage requires compliance of these voltages’ limit values. To ensure compliance with these requirements have been developed algorithms for calculating of currents and voltages distribution along the grounded phase/cable of disconnected power line, induced by the electric field of operating three-phase overhead power line without transposition, with full and incomplete complete phases transposition section .

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49

Zhou, Xue Song, Hua Xin Zhai, and You Jie Ma. "A Coordinating Procedure for Tracing Static Bifurcation Points of Voltage Instability." Advanced Materials Research 413 (December 2011): 90–94. http://dx.doi.org/10.4028/www.scientific.net/amr.413.90.

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Based on static bifurcation theory, a systematic procedure for tracing the bifurcation points of power system voltage instability was presented. Two main kinds of bifurcations, a common saddle node bifurcation (SNB) and a kind of bifurcation—limit induced bifurcation (LIB), which can cause the voltage collapse, were studied simultaneity and all types of device limits were considered. Firstly, make sure the mathematical model of the system. Secondly, starting from the basic running point of power systems, a predictor scheme was presented to find all the limit points (LP) and identify the LIB points; an adaptive step size control method considering the curvature of the manifold was introduced for tracing the equilibrium manifold and the detection of the SNB points without the existing of LPs. The two schemes were combined to lead a more effective method for SNB, LP, and LIB detection.

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50

Li, Tian Tian, Jiang Bo Wang, and Wen Li Wang. "Research on Peak Capacity of Distributed Photovoltaic Generation Based on Voltage Deviation Model in Distribution Network." Applied Mechanics and Materials 734 (February 2015): 775–80. http://dx.doi.org/10.4028/www.scientific.net/amm.734.775.

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Large-scale grid-connected photovoltaic generators will cause out-of-limit of voltage deviation. The model of voltage drop caused by loads and voltage rise caused by PV generators are established under different loads or PV distribution modes along the line, and the maximum allowable capacity of PV power injected into the grid without causing over-voltage is calculated, assuming the bus voltage deviation reaching the upper limit. The maximum PV penetration level of typical distribution lines is derived under the condition that PV generators is of the same distribution mode with loads, and the voltage margin at the head end of the line without causing over-voltage is proposed. The results show that over-headlines can carry much more PV power than cables, and over-voltage will be avoided by controlling the PV power according to the connected bus voltage, and suitably lowering the bus voltage will allow more PV to connect into the grid.

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