Gotowa bibliografia na temat „Fast Decoupled Load Flow (FDLF) Method”

Fuzzy logic is used to solve the load flow and contingency analysis problems, so decreasing computing time and its the best selection instead of the traditional methods. The proposed method is very accurate with outstanding computation time, which made the fuzzy load flow (FLF) suitable for real time application for small- as well as large-scale power systems. In addition that, the FLF efficiently able to solve load flow problem of ill-conditioned power systems and contingency analysis. The FLF method using Gaussian membership function requires less number of iterations and less computing time than that required in the FLF method using triangular membership function. Using sparsity technique for the input Ybus sparse matrix data gives reduction in overall computation time and storage requirements. The performance of the used methods had been tested on two typical test systems being the IEEE 14-bus and 30-bus systems in addition to the 362-bus Iraqi National Grid. All the obtained results under normal operating conditions show that the computation time of the fuzzy Load Flow (FLF) is less than the fast decoupled load flow (FDLF).

Abstract Ideally, an AC power supply should constantly provide a perfectly sinusoidal voltage signal at every customer location. Nowadays, many power electronic equipment’s are used in industry in seeking higher system reliability and efficiency and more electronic or microprocessor controllers are used in power system to control AC/DC transmission lines or loads. Moreover, the importance of green energy such as wind and solar is continually growing in our societies not only due to environmental concerns but also to resolve the problem of access to electricity in rural areas. As a result of these issues, power quality problems especially generation of harmonics are on the rise in the distribution network. In electrical power system, harmonics have a number of undesirable effects on power system devices as well as on their operation. It therefore becomes imperative for power system engineers to analyse the penetration of harmonics from the various sources into the network which commonly is known as harmonic power flow evaluation. This paper proposed a novel fast hybrid frequency domain approach (FHA) to evaluate the steady state harmonic power flow with discrete harmonic frequency. The proposed method is applied to IEEE – 14 bus, IEEE New England 39 - bus, IEEE – 57 bus and IEEE 118 - bus power system respectively and compared with Newton – Raphson (NR) load flow method and Fast decoupled load flow method (FDLF) and the results validate the accuracy, robustness and authenticity of the proposed method.

The power flow calculation is study the steady-state operation of the power system as basic electrical calculations. It is given the power system network topology, device parameters and determines system health boundary conditions, draw a detailed operating status of the power system through numerical simulation methods, such as voltage amplitude and phase angle on the bus system the power distribution and the power loss. Flow calculation is the power system operation, planning and safety, reliability analysis, is fundamental to the system voltage regulation, network reconfiguration and reactive power optimization must call the function, so the trend has very important significance to calculate the power system.

This paper presents an efficient fast decoupled power flow control method e.g. method for automatic adjustment of a phase shifting transformers (PST) for specific line flows. The effects of a PST are represented by injection model and the corresponding extension of conventional load flow equations is made. Furthermore, the load flow control by means of PST is modeled by additional equations. For solution of the power flow control problem defined the special fast decoupled procedure is developed. The high numerical efficiency and simplicity of this procedure has been established on the example of real interconnection formed by the power system of Serbia and Montenegro, Romania, Bulgaria, Former Yugoslav Republic of Macedonia, Greece and Albania (Second UCTE synchronous zone).

The capability to rapidly execute the power flow (PF) calculations permit engineers in assured with stay bigger assured within the dependability, protection, and economical operation of their system within the case of planned or unplanned instrumentality failures. The purpose of this work is to investigate the use of FPGA characteristics to speed up power flow computing time for the on-line monitoring system of a power system. The work comprises which is the development of the Power flow program using the Fast-decoupled method based on FPGA (Field Programmable Gate Array), and LABVIEW (graphical programming environment). The program delivered very satisfactory results to solve a 30-bus test system. These findings suggest that in general that differences between the proposed work and the conventional fast decoupled method are satisfactory. As for the execution time, because the FPGA uses parallel solutions, the performance of the proposed method is faster. Also, the engagement of the FPGA and the LabVIEW program presented an effective monitoring system for observing the power system.

This article presents an approach using cubic spline function to study Load Flow with a view to acquiring a reliable convergence in the Bus System. The solution of the power flow is one of the extreme problems in Electrical Power Systems. The prime objective of power flow analysis is to find the magnitude and phase angle of voltage at each bus. Conventional methods for solving the load flow problems are iterative in nature, and are computed using the Newton-Raphson, Gauss-Seidel and Fast Decoupled method. To build this method, this paper used cubic spline function. This approach can be considered as a ‘two stage' iterative method. To accredit the proposed method load flow study is carried out in IEEE-30 bus systems.

This paper presents an advanced method for active power flow control by use of static phase shifting transformer. It is based on non-standard load-flow model, which enables more accurate evaluation of the relevant technical effects of phase shifting transformer installation. For solution of the power flow control problem defined, the special fast decoupled procedure is developed. The high numerical efficiency and simplicity of this procedure has been established on the example of real interconnection formed by the Electric Power System of Serbia and Montenegro, Romania, Bulgaria, Former Yugoslav Republic of Macedonia, Greece and Albania (ex Second UCTE synchronous zone).

This paper deals with the security aspects of power system by evaluating the severity of transmission line outage. MW security assessment is made by determining the power flow in the line using load flow for each contingency. The severity of contingency is measured using a scalar index called performance index (PI). DC load flow and Fast Decoupled load flow are used as approximate and exact load flow methods for MW security assessment respectively. Contingency analysis is carried out and ranked lists in the decreasing order of severity based on PI values are prepared for standard test systems. The severity of line is evaluated and compared using these load flow methods. A new method is proposed to avoid Masking problems in MW security assessment. Security analysis is made on standard test systems such as 5, 6, IEEE 14 and IEEE 30 bus systems under present study.

The state of a given power system i.e. voltage magnitudes and angles at all the buses can be computed using the Newton-Raphson Load Flow (NRLF) method when active power and reactive power loads are specified at all the buses of the system. This computation can be carried out more e ciently(in terms of computer memory and time) using the Fast Decoupled Load Flow(FDLF) method for a large class of systems. These methods are the most widely used methods in power system studies. NRLF and FDLF methods require modifications, if voltage magnitude is spec-i ed at some of the generator buses instead of the reactive power load. In such situations, generator reactive power outputs(manipulated by adjusting the field excitation) have to be adjusted to meet this specification. This necessitates the determination of the value of these additional control variables. There are some more similar adjustments that are required to be made in a practical load flow. Sometimes, the voltage at some load buses may be specified. They are to be maintained at the scheduled value using the taps on in-phase transformers(OLTC transformers). Similarly, it is possible in some situations that the active power flow in some lines are specified to be kept at a particular value. The device which facilitates such a control is the phase shifting transformer(PSTs) and the PST tap value is the additional control variable to be determined. The other operation of interest in interconnected power systems is the area interchange control(AIC). This requires that the sum of active power flow between two areas of the system is maintained at the specified value. The control variable value that enables this adjustment is the active generation in a particular generator bus in the area referred to as a swing bus. The load flow problem is referred to as a adjusted load flow problem in cases where in, some of these control variables must also be determined in addition to the state of the system. It must be pointed out here that the control variables must be strictly kept within their limits while bringing the controlled variables to their specified values. If a control variable tends to reach a value beyond its limits, then it is to be set at the limit and the corresponding controlled variable will not be at its scheduled value. Adjusted load flow problems generally involve many control variables of the same type or multiple control variables of different types. The challenge in finding adjusted load flow solutions stems from the fact that the relation between the controlling and controlled variables is not one to one; each controlling variable affects many of the controlled variables. The existing approaches of adjusted load flow solutions generally consider only one type of these adjustments. There are only a very few attempts where more than one type of adjustment is considered. The two broad directions pursued for developing algorithms for adjusted solutions, by the earlier researchers are (1) Introducing additional equations in order to include control variable(between iterations) and (2) Adjusting the controlling variables between unadjusted load flow solution iterations based on the local sensitivity of the controlled variable with respect to a particular controlling variable. The schemes in use for finding adjusted load flow solutions have a flavour of trial and error type of algorithms. Their success in any situation is known to depend on specific details of implementation. Implementation details that guarantee success are not in the public domain. Many times they exhibit oscillatory convergence behaviour requiring very large number of iterations or fail to converge. It is also known that in some situations these algorithms could converge to anomalous solutions(solutions that are inconsistent with practical system behaviour). Such limitations of the existing approaches and also the need for developing better methods is well documented in the literature. Some recent work has shown the promise of the formulation of the adjusted load flow problem in the complementarity framework considering a few of the adjustments. This thesis is intended to further explore this promising direction of investigation. In particular, in this thesis, we develop new algorithms in complementarity framework for the following situations and demonstrate their attractive features as compared with the existing approaches. In this thesis, the following algorithms have been proposed, developed, tested and their performance compared with the existing algorithms. . Two algorithms for including OLTC adjustments, in the FDLF method as Mixed Complementarity Problem(MCP) and Non-linear Complementarity(NCP) formulations. In addition, the above algorithms are further extended to incorporate generator bus Q-limit adjustments simultaneously with the OLTC adjustments. Two new algorithms(two each in MCP and NCP formulations) are developed to handle generator Q-limits and OLTC adjustments individually as well as together in the NRLF formulation in rectangular coordinates. Four algorithms(two in MCP and two in NCP) to handle PST constraints in NRLF and FDLF methods. Four algorithms(two in MCP and two in NCP) to handle AIC constraints in NRLF and FDLF methods. In addition, the PST and AIC adjustment algorithms above are combined to simultaneously carry out PST and AIC adjustments in NRLF as well as FDLF methods. Four algorithms(two for NRLF and two for FDLF) to simultaneously incorporate all the four adjustments simultaneously using MCP and NCP formulations. These algorithms are also shown to be capable of incorporating simultaneously any subset of these four adjustments The thesis focusses only on incorporating adjustments in the NRLF and FDLF methods as they are the most widely used schemes in the industry as well as the academia. It is also pointed out that the investigations here consider the adjustment problem in the traditional framework and hence, none of the power electronics based control equipment or the modern distributed generation sources are considered here. Results of extensive computational experiments are presented and the attractive performance of the new algorithms as compared with the traditional ones are high-lighted. All the new algorithms developed here are fundamentally different from the existing adjusted load flow approaches(not based on complementarity framework) in that they meet the specifications on the system variables and limits on the controlling variables automatically; without requiring either heuristic algorithmic choices or problem specific algorithm manipulation - a fairly common feature in all the existing approaches. This extremely desirable feature of the proposed algorithms is due to the fact that the pro-posed formulations for the adjusted load flow problems in complementarity framework, transform these problems to that of solving a fixed set of non-linear equations. The results in the thesis provide strong evidence of the promise of the new methods for adoption into the widely used NRLF and FDLF programs so as to make solving the adjusted load flow problem as simple as solving the unadjusted load flow problem.