Equilibrium Optimizer for LFO Damping in Multimachine Power System Networks

An efficient and most famous tool to enhance damping of the power system low frequency oscillations is the conventional widely used lead-lag Power System Stabilizer (PSS). To achieve the desired level of robust performance under transient situation, selecting a suitable design method for optimal tuning of PSS parameters is very important in multi-machine power system. Because, it is a multimodal and difficult combinatorial optimization problem, this paper presents a novel parameter automation strategy for Particle Swarm Optimization (PSO) called PSO with Time-Varying Acceleration Coefficients (PSO-TVAC). This optimization method has a strong ability to successfully control both global and local search in each iteration process for considerably increasing the probability of finding the global optimum solution. The PSO-TVAC algorithm is applied to optimal tuning PSS parameters problem in order to reduce the PSS design effort and find the best possible solution within a reasonable computation time. For this reason, the robustly selection of PSSs parameters is converted as an optimization problem based on the time domain-based objective function under different operating conditions. The robustness of the proposed method is demonstrated on a multi-machine power system in comparison with the classical PSO and conventional method based designed PSSs. It is shown through the nonlinear time domain simulation and some performance indices for a wide range of loading condition. The analysis of the results shows that the improved PSO-TVAC is not only very effective but also provides an excellent ability for damping low frequency oscillations and greatly enhance the dynamic stability of the power system. Moreover, the proposed PSO-TVAC algorithm is superior than that of the classical PSO one in terms of accuracy, convergence and computational effort. Key words: Power system stabilizer (PSS) design, particle swarm optimization, power system dynamics, time-varying acceleration coefficients.

This paper presents the study related to the power system stabilizer (PSS) design for northern regional power grid (NRPG) of India. The location of local PSS is suggested by participation factor approach. The power-voltage reference (PVr) characteristic of the suggested generator is used to obtain the compensator block of the local PSS. Internal states are lost while performing model order reduction therefore, the shaft dynamics are not available in the reduced order model for disabling. Therefore compensating block has to be design by utilizing full order system. But, the gain of the PSS can be tuned by utilizing the reduced order model. Next, the model order reduction (MOR) is performed with a target on preserving the characteristics and behavior of dominant inter-area mode in reduced order model (ROM). Thereafter, the tuned gain using ROM is combined with compensator and washout filter to obtain PSS for 44th generator (G44). The performance of designed PSS is investigated under five cases of disturbances.

In this paper a robust method is presented for the combined design of STATCOM and Power System Stabilizer (PSS) controllers in order to enhance the damping of the low frequency oscillations in power systems. The combined design problems among PSS and STATCOM internal ac and dc voltage controllers has been taken into consideration. The equations that describe the proposed system have been linearized and a Fuzzy Logic Controller (FLC) has been designed for the PSS. Then, the Particle Swarm Optimization technique (PSO) which has a strong ability to find the most optimistic results is employed to search for the optimal STATCOM controller parameters. The proposed controllers are evaluated on a single machine infinite bus power system with the STATCOM installed in the midpoint of the transmission line. The results analysis reveals that the combined design has an excellent capability in damping a power system's low frequency oscillations, and that it greatly enhances the dynamic stability of power systems. Moreover, a system performance analysis under different operating conditions and some performance indices studies show the effectiveness of the combined design.

This paper aims to present the design of power system stabilizer (PSS) as a second-order sliding mode controller (SOSMC). Power systems have always been growing into more dynamic and complex systems. This is because of continuously occurring disturbances and parametric uncertainties in power systems due to changing loads. One of the major problems with this area is small frequency oscillations which lead to the system instability if these oscillations are not damped properly and also reduce power transfer capability. Therefore, it is essential to use power system stabilizers (PSS) to damp out small frequency oscillations. In this paper, single machine infinite bus (SMIB) system is used as study system. Sliding mode control (SMC) is a nonlinear and very robust control technique. Advantages of this controller can be used to control the power systems in order to increase the stability. But SMC has a major disadvantage of chattering. SOSMC overcomes the disadvantages produced by SMC. Therefore, in this paper, PSS is designed as SOSMC using twisting algorithm and applied to SMIB. The robustness of PSS as SOSMC is demonstrated by carrying out comparative simulation under different operating conditions of the SMIB power system.

This paper reports a new technique for achieving optimized design for power system stabilizers. In any large scale interconnected systems, disturbances of small magnitudes are very common and low frequency oscillations pose a major problem. Hence small signal stability analysis is very important for analyzing system stability and performance. Power System Stabilizers (PSS) are used in these large interconnected systems for damping out low-frequency oscillations by providing auxiliary control signals to the generator excitation input. In this paper, collective decision optimization (CDO) algorithm, a meta-heuristic approach based on the decision making approach of human beings, has been applied for the optimal design of PSS. PSS parameters are tuned for the objective function, involving eigenvalues and damping ratios of the lightly damped electromechanical modes over a wide range of operating conditions. Also, optimal locations for PSS placement have been derived. Comparative study of the results obtained using CDO with those of grey wolf optimizer (GWO), differential Evolution (DE), Whale Optimization Algorithm (WOA) and crow search algorithm (CSA) methods, established the robustness of the algorithm in designing PSS under different operating conditions.

In this paper, the authors are willing to find the optimal and robust design for power system stabilizers (PSSs) in a multi-machine power system. In this regard a new Meta heuristic method as Simulated Annealing (SA) is used. The PSS parameters are computed to assure maximum damping performance under different scenarios. A multi machine electric power system is used to illustrative the performance of proposed method. The efficacy of this technique in damping local and inter-area modes of oscillations in multimachine power systems is confirmed through nonlinear simulation results. Simulation results are carried out by numerical simulations on MATLAB software. Keywords: Multi Machine, Power System Stabilizer, Low Frequency Oscillations, Simulated Annealing

Accurate damping of inter-area and intra area oscillations are very much critical in the stability of electric power system. Power system stabilizer (PSS) is mainly used as auxiliary controllers to damp out the low frequency oscillations in the area of electric power system. The tuning of Conventional Power System Stabilizer (CPSS) for a nonlinear power system should be robust such that overall system stability can be improved under several operating points. Today's scenario, various populations based heuristic algorithms are available to minimize the effect of stability problem by properly tuning the parameters of CPSS. In this paper presents a new heuristic population based optimization technique named as Group Search Optimization (GSO) algorithm to tune the PSS parameters for a multi-machine system for different operating conditions. The importance of the GSO algorithm is evaluated and compared for damping the system oscillations during small and large disturbances, and their robustness is illustrated using the transient signal analysis.

It is very important to take into consideration time delay in wide area power system stability; the design of PSS (Power System Stabilizer) should consider global optimization with WAMS (Wide Area Measurement System) time delay. Newly designed PSS should be insensitive to time delay and suppress internal low frequency oscillations. It is used as feedback signal and is real-time synchronous that WAMS signal shows. Power system is modeled with the consideration of time delay. LMI (Linear Matrix Inequalities) is used to solve the stability condition of time delay system. Based on the time-delay effect of the wide-area measurement signals, this paper redesigned the PSS with global optimization of power system. The attached two-area-four-machine system simulation illustrates that wide-area PSS designed by global optimization with the consideration of time-delay can limit internal low frequency oscillation with time-delay insensitivity, and improve the stability of power system. It implements global optimization of PSS with WAMS time delay stability.

This paper represents, the enhancement of power system stability by coordinating control design of power system stabilizer (PSS) and static synchronous series compensator (SSSC). The coordinated controller's parameters are formulated as an optimization problem and to search for such optimal parameters firefly (FF) algorithm is used in both cases of single machine infinite bus and multi machine power system(MMPS). The coordinately control design of power system stabilizer and PID based SSSC based controller uses speed deviation as input signal. The dynamic performance of the proposed technique is obtained under different loading conditions and different position of fault conditions. The effectiveness and robustness of coordinated design approach is discussed to improve the damping of power system oscillation and hence stability of power system.

In power system, the application of the power system stabiliser (PSS) has been proved to overcome the stability of power system. It is necessary to determine the appropriate PSS parameters. In this paper, a new cost function is presented for the tuning of PSS parameters. Optimisation of PSS parameters has been done by particle swarm optimisation algorithm. The power plant system that is simulated in this paper is one machine to infinite bus system. The responses of the PSS tuned with PSO and conventional power system stabiliser (CPSS) are compared with together.

Low frequency oscillations are observed when large power systems are interconnected by relatively weak tie-lines. Power System Stabilizers (PSS) are incorporated in the excitation system of the generators to enhance damping of these low frequency oscillations. In this paper, the design of multiple PSS in a multi-machine power system (MMPS) using Cat Swarm Optimization (CSO) algorithm has been proposed. The design problem of the PSS has been formulated as an optimization problem and CSO has been employed to search for optimal controller parameters. It has been shown that the stability performance of the system can be improved by minimizing the eigenvalue based objective function comprising of the damping factor and the damping ratio of the poorly damped electromechanical modes. Eigenvalue analysis and nonlinear simulation results have also been presented for various loading conditions and system configurations to show the effectiveness and robustness of the proposed controllers and their ability to provide efficient damping of low frequency oscillations.

Inter Area Oscillations amounting to a major portion of the class of low frequency oscillations, are detrimental to the dynamic stability of the present day power system. Power system stabilizer (PSS) installed throughout the system aids in mitigating such oscillations. Static synchronous compensator (STATCOM) based damping controllers installed in the system also provide oscillation damping apart from their intended purpose of reactive power compensation. Hence to improve the overall performance coordinated design of PSS and STATCOM is essential. The coordinated design of power system stabilizer (PSS) and static synchronous compensator (STATCOM) for mitigation of inter area oscillations is presented in this paper. The coordinated design is formulated as an optimization problem and particle swarm optimization (PSO) is employed for this design. Then the designed PSS and STATCOM are implemented in the test system and the response is analysed. The test system is simulated with and without Power system stabilizer and static synchronous compensator. The simulation results show that the coordinated design mitigates the inter area oscillations in an effective way.

The design of power system stabilizer (PSS) is load-dependent and needs continuous adjustment at each operating condition. This paper aims at introducing a robust non-fragile PSS for interconnected power systems. The proposed controller has the capability of adaptively tuning online its rule-base through a variable-structure direct adaptive control algorithm in order to rigorously attain the desired objectives. The PSS controller acts on damping the electromechanical modes of oscillations not only through a wide range of operating conditions but also in presence of different disturbances. Using MATLABTM-Simulink, simulation results significantly verify that the proposed controller provides favorable performance and efficiently contributes towards enhancing the system dynamic behavior when applied to the four machines two-area power system that mimics the typical system behavior in actual operation. The interaction between the variable-structure adaptive fuzzy-based power system stabilizer (VS-AFPSS) and the existed typical ones inside the interconnected power systems has been explicitly discussed. Compared to other conventional controllers, VS-AFPSS enables better damping characteristics to both local and inter-area oscillation modes considering different operating conditions and sever disturbances.

Power system excitation control using master-slave fuzzy power system stabilisers

This paper presents a new concept to design optimal power system stabilizer (PSS) as a damper on a multimachine power system control. This concept is developed 6om the proportional and integral (PI) control and linear quadratic regulator (LQR) method as a modem tool to design the PSS as optimal PSS. Using this concept, the stabilizers of the multimachine are designed for the turbine and excitation system side using the Riccati solution, as a character of LQR optimal control method solving. In this paper, the design of the optimal PSS is compared with the conventional PSS (CPSS) and No PSS system. In the final results, the application of optimal PSS as a damper of power system can greatly improve the performances of multimachine power system, and it shows the best results