Designing power system stabilizer for multimachine power system using neuro-fuzzy algorithm

This paper describes a design procedure for a fuzzy logic based power system stabilizer (FLPSS) and adaptive neuro-fuzzy inference system (ANFIS) and investigates their robustness for a multi-machine power system. Speed deviation of a machine and its derivative are chosen as the input signals to the FLPSS. A four-machine and a two-area power system is used as the case study. Computer simulations for the test system subjected to transient disturbances i.e. a three phase fault, were carried out and the results showed that the proposed controller is able to prove its effectiveness and improve the system damping when compared to a conventional lead-lag based power system stabilizer controller

Dynamic Stability Studies Of Generators In Power System Using Fuzzy Logic Controller Based Power System Stabilizer

Excitation systems are affected by low frequency oscillation (LFO)when they are subjected to small perturbations.Damping during the LFOis enhanced via the addition of power system stabilizer (PSS) to the excitation system.This research entails a study on fuzzy logic controller power system stabilizer (FLCPSS) for the purpose of enhancing the stability of a single machine power system.In order to accomplish the stability enhancement,two approaches were used to design fuzzy logic controller (FLC).The first approach includes the use ofgenetic algorithm (GA) to design the PSS.The second approach entails the use of particle swarm optimization (PSO) to design the PSS.The performance of these two approaches is compared with the systemand without PSS.The stabilizing signals were computed using the fuzzy membership functions depending on these variables.The simulations were tested under different operating conditions and also tested with different membership functions.The simulation is implemented using Matlab /Simulink and the results have been found to be quite good and satisfactory.Electro-mechanical oscillations were created in the event of trouble or when there was high power transfer through weak tie-line in the machines of an interrelated power network.This research presents an analysis on the change of speed (Δω), change of angle position (Δδ) and tie-line power flow (Δp).FLC which includes two areas of symmetrical systems are connected via tie-line to identify the performance of the controllers.Simulation results of the fuzzy logic based controller indicate dual inputs of rotor speed deviation and generator’s accelerating power.Two generators have been used to control the arrangement in the tie-line system.The single fuzzy logic controller (S-FLC) has been used as a primary controller and the double fuzzy logic controller(D-FLC) has been used as a secondary controller.Additionally,the system shows a comparison between the two controllers,namely the S-FLC and D-FLC which have been used to achieve the best results.Notably, the double fuzzy controller has been found to have a greater effect on the multi-machine system and it is smoother than the single fuzzy controller as it increased the damping of the speed Δω and rotorangle (degree) Δδ. Its simplicity has made it to be a good controller.In conclusion,much better response can be attained from the S-FLC) if there is careful timing of the scaling factors

Adaptive Fuzzy Gain of Power System Stabilizer to Improve the Global Stability

The lead-lag power system stabilizer has several parameters to be optimized.In fact, the number of these latter increases with the number of generators constituting the multi-machine system.In this work, we propose anew approach of an adaptive and robust PSS; it achieves encouraging results by adjusting the gain using fuzzy logic and in the same time we use the same PSSs for each machine. In the first place, we could check that the gain is among the most critical parameters of the lead lag PSS. The parameters are globally optimized by the genetic algorithm, after that an expertise on the speed and the gain variations allow the value prediction according to the velocity deviation. To validate our results, a robustness test was made on a multimachine system IEEE (3 machines 9 bus), for different loads and the results showed good performance and robustness of the presented PSS

Dynamic Stability Enhancement Through the Application of Stabilizers of Electromechanical Oscillations

Power system dynamic stability is one of key issues system engineers face. Oscillations that regularly occur in the system, limit the transmission capability of the network. The need to study the stability of power systems has been increasingly growing along with the development of power systems and their grouping into large interconnections. The focus of this paper is determining the dynamic stability of a synchronous generator, and thus the power system, by applying the general theory of stability of dynamic systems. Furthermore, the procedure for the initial adjustment of the parameters of a conventional (IEEE3 type PSS1A) stabilizer of electromechanical oscillations is briefly described based on the frequency response analysis of a linear generator model also known as the Heffron-Phillips generator model

Dynamic Stability Enhancement Through the Application of Stabilizers of Electromechanical Oscillations

Power system dynamic stability is one of key issues system engineers face. Oscillations that regularly occur in the system, limit the transmission capability of the network. The need to study the stability of power systems has been increasingly growing along with the development of power systems and their grouping into large interconnections. The focus of this paper is determining the dynamic stability of a synchronous generator, and thus the power system, by applying the general theory of stability of dynamic systems. Furthermore, the procedure for the initial adjustment of the parameters of a conventional (IEEE3 type PSS1A) stabilizer of electromechanical oscillations is briefly described based on the frequency response analysis of a linear generator model also known as the Heffron-Phillips generator model

DESIGN OF REAL-TIME FUZZY LOGIC PSS BASED ON PMUs FOR DAMPING LOW FREQUENCY OSCILLATIONS

Poorly damped low frequency oscillations is one of the main problems threatening safe and stable operation of the interconnected power systems and reducing the capability of transmission the power. The generator's excitation system has been supplemented with the Power System Stabilizer (PSS) in order to improve the damping of these low oscillations. In the latest smart power grids, the Phasor Measurement Units (PMUs) become a fundamental element in the monitoring, protection and control applications as PMU signals are more accurate than the conventional measurement units and real time GPS stamped. In this study, Fuzzy Power System Stabilizer (FPSS) has been designed and its performance in damping inter-are oscillations compared with the conventional PSS (CPSS) based on the simulation with MATLAB/Simulink model. The results of the simulation with the Simulink model proved that the performance of the designed FPSS in damping inter-area oscillation is better than the CPSS. One of the main features of fuzzy controller is that it doesn't require mathematical modeling as it is designed based on the time-domain and the operator experience while, in contrast, the conventional PSS requires to be designed in the frequency domain. Real Time Digital Simulator (RTDS) has been used to develop the real-time models of the test systems. The time-domain simulations with the RTDS model when the system subjected to the large disturbance (three-phase to ground fault) have been performed to show that the designed FPSS improved the damping of the oscillations effectively. The simulation results have been verified by modal analysis

Analysis and robust decentralized control of power systems using FACTS devices

Today\u27s changing electric power systems create a growing need for flexible, reliable, fast responding, and accurate answers to questions of analysis, simulation, and design in the fields of electric power generation, transmission, distribution, and consumption. The Flexible Alternating Current Transmission Systems (FACTS) technology program utilizes power electronics components to replace conventional mechanical elements yielding increased flexibility in controlling the electric power system. Benefits include decreased response times and improved overall dynamic system behavior. FACTS devices allow the design of new control strategies, e.g., independent control of active and reactive power flows, which were not realizable a decade ago. However, FACTS components also create uncertainties. Besides the choice of the FACTS devices available, decisions concerning the location, rating, and operating scheme must be made. All of them require reliable numerical tools with appropriate stability, accuracy, and validity of results. This dissertation develops methods to model and control electric power systems including FACTS devices on the transmission level as well as the application of the software tools created to simulate, analyze, and improve the transient stability of electric power systems.;The Power Analysis Toolbox (PAT) developed is embedded in the MATLAB/Simulink environment. The toolbox provides numerous models for the different components of a power system and utilizes an advanced data structure that not only increases data organization and transparency but also simplifies the efforts necessary to incorporate new elements. The functions provided facilitate the computation of steady-state solutions and perform steady-state voltage stability analysis, nonlinear dynamic studies, as well as linearization around a chosen operating point.;Applying intelligent control design in the form of a fuzzy power system damping scheme applied to the Unified Power Flow Controller (UPFC) is proposed. Supplementary damping signals are generated based on local active power flow measurements guaranteeing feasibility. The effectiveness of this controller for longitudinal power systems under dynamic conditions is shown using a Two Area - Four Machine system. When large disturbances are applied, simulation results show that this design can enhance power system operation and damping characteristics. Investigations of meshed power systems such as the New England - New York power system are performed to gain further insight into adverse controller effects

A Review On SVC Control For Power System Stability With And Without Auxiliary Controller

Since the beginning of the last century, power system stability has been recognized as a vital problem in securing system operation. Power system instability has caused many major blackouts. This paper reviewed the previous technical works consisting of various methods of optimization in controlling power system stability. The techniques presented were compared to optimize the control variables for optimization of power system stability. Power system stability enhancement has been investigated widely in literature using different ways. This paper is focusing on SVC performance for enhancing power system stability either through SVC controlled itself or SVC controlled externally by other controllers. Static VAR compensators (SVCs) are used primarily in power system for voltage control as either an end in itself or a means of achieving other objectives, such as system stabilization. The analysis on performance of the previous work such as advantages and findings of a robust method approach in each technique was included in this paper