Stability Of Multi-machine Power System Research Articles

Amended GWO approach based multi-machine power system stability enhancement

The conception of electromechanical oscillations initiates in the power network when there is an installation of the generator in parallel with the existent one. Further, the interconnection of multiple areas, extension in transmission, capricious load characteristics, etc. causes low-frequency oscillations in the consolidated power network. This paper proposes variants of a booming population-based grey wolf optimization (GWO) algorithm in the tuning of power system stabilizer parameters of a multi-machine system in damping low-frequency oscillations. The parameters have been tuned by framing an objective function considering the improving damping ratios for the system states with lesser damping ratios and shifting the system eigenvalues towards the left-hand side of s-plane for the improved settling characteristics for the oscillations in the system. The requisites of stabilizer strategy are mapped with the hallmarks of prevalent algorithms and designed hybrid versions of GWO for the enhancement of the multi-machine power system stability. Four variants of GWO technique are nominated based on the competent stabilizer performance namely, modified grey wolf optimization (MGWO), hybrid MGWO particle swarm optimization (MGWOPSO), hybrid MGWO sine cosine algorithm (MGWOSCA) and hybrid MGWO crow search algorithm (MGWOCSA) for the designed multi-machine power network. The proposed methods have been realized with the statistical analysis on the 23 benchmark functions. Nonparametric statistical tests, namely, Feidman test, Anova test and Quade tests, have been performed on the test system, further analysed in detail. A detailed comparative analysis under the self-clearing fault is presented to illustrate the suitability of the proposed techniques. For the analysis purpose, the location of system eigenvalues has been observed along with their oscillating frequencies and corresponding damping ratios. Further, the damping nature offered with considered system uncertainty for the system states also presented with the PSS parameters obtained by the proposed algorithms.

Robust Decentralized Control of Synchronous Generators for Improving Transient Stability of Multimachine Power Grids

In this article, a decentralized controller for improving the transient stability of multimachine power systems is proposed. A coordinated control of excitation and steam turbine of synchronous generators is developed based on model predictive control (MPC) strategy that explicitly takes into account physical constraints of the actuators. A tube-based MPC is developed to ensure the robustness and convergence of the control signal in the presence of exogenous perturbations and modeling uncertainties. To attenuate the noise level in measurement signals that are used in the controller, an improved tracking differentiator is utilized. The proposed controller is implemented locally at individual synchronous generator stations which makes it suitable for practical applications. The performance of the proposed control scheme is studied using 39-bus New England test system. The simulation results show that the proposed robust approach enhances the transient stability of the power systems.

A nonlinear coordinated approach to enhance the transient stability of wind energy-based power systems

This paper proposes a novel framework that enables the simultaneous coordination of the controllers of doubly fed induction generators &#x0028 DFIGs &#x0029 and synchronous generators &#x0028 SGs &#x0029 . The proposed coordination approach is based on the zero dynamics method aims at enhancing the transient stability of multi-machine power systems under a wide range of operating conditions. The proposed approach was implemented to the IEEE 39-bus power systems. Transient stability margin measured in terms of critical clearing time along with eigenvalue analysis and time domain simulations were considered in the performance assessment. The obtained results were also compared to those achieved using a conventional power system stabilizer &#x002F power oscillation &#x0028 PSS &#x002F POD &#x0029 technique and the interconnection and damping assignment passivity-based controller &#x0028 IDA-PBC &#x0029 . The performance analysis confirmed the ability of the proposed approach to enhance damping and improve system &#x02BC s transient stability margin under a wide range of operating conditions.

Modelling and Simulation for Small Signal Stability of Multi-machine Power System under Various Disturbance Conditions

This paper presents the small signal stability of multi-machine power system over the 58-Bus, 26-Machine, Yangon Distribution Network and is validated with MATLAB software under various disturbance conditions. Time-domain solution analysis is employed to determine the small signal dynamic behavior of test system. Transtability model is used to perform time-domain simulation in SIMULINK. The simulation is carried out for normal condition, reference voltage of regulator (Vref) disturbance, mechanical torque (Tm)disturbance and network (fault) disturbance and the conditions of change in center of inertia for rotor angle (delta COI), slip for center of inertia (slip COI), field current and mechanical torque are observed. According to the simulation results, perturbation of Vref shows only instability on the system. But ramping of Tm and network disturbance can cause large disturbance on the system and unstable conditions can be observed.

Decentralized constrained optimal control of the multimachine power system stability improvement

<p>The paper proposes, a decentralized constrained optimal control of the multimachine power system stability. Today’s power network conditions, operating closer to their limits. Alternative Current power grids are more vulnerable and subject to instability than ever before. A three machine power system and four machines, power system connected with a transmission line lossy. Nonlinear controllers are more complex structure and inflexible to be used in practice paralleled with a linear controller. The linearized dynamical equations of the multimachine power system are near to an equilibrium point and it can be stabilized by using a decentralized constrained controller based on optimal control. The feedback controller, which comprises independent control stations receives the measurement data and influences the control input of the machine is only attached to the subsystems. State feedback controller guarantees the closed-loop system is asymptotically stable can guarantee the performance index. It bases designed controlled systems on the algebraic Riccati equations and all its poles are in the closed left half-plane. Decentralized constrained optimal control of the multimachine power system is achieved through simulation of the results. This achievement of results is proposed by improves power system stability.</p>

Decentralized constrained optimal control of the multimachine power system stability improvement

Decentralized constrained optimal control of the multimachine power system stability improvement

Machine Learning Algorithm Based Static VAR Compensator to Enhance Voltage Stability of Multi-machine Power System

Machine Learning Algorithm Based Static VAR Compensator to Enhance Voltage Stability of Multi-machine Power System

Optimal siting, sizing, and parameter tuning of STATCOM and SSSC usingMPSO and remote coordination of the FACTS for oscillation damping of powersystems

In electromechanical oscillation damping within power system, power system stabilizers (PSSs) are often deployed. However, a PSS is less effective in damping interarea oscillation and is limited by changes in network configuration due to weak tie-lines and load variations. Consequently, this paper presents a wide-area coordination approach that damps interarea oscillations using FACTS devices and phasor measurement units. We selected a static synchronous compensator (STATCOM) and static series synchronous compensator (SSSC) for realistic power system interarea oscillation damping. The performance of the coordinated FACTS installed in a power system depends on their suitable locations, sizes, tuned parameters, and remote input signal selection. Hence, we formulated a multiobjective problem to provide the STATCOM and SSSC's optimal solutions using multiobjective particle swarm optimization. In addition, we employed a participation factor to select suitable generator speed deviations as the wide area stabilizing signal. The proposed approach was tested on different configurations of the Kundur $2$-area $4$-machine test system within MATLAB and Psat environments. The outcome of the nonlinear simulation proved that the multimachine power system stability was enhanced.

Power System Transient Stability Study by Involving Higher Order Corrections in Improved Quadratic Lyapunov Function for Singular Perturbed Model of Synchronous Generator

The assessment of transient stability of multi-machine power system, in a post-fault scenario, is a very challenging task due to highly non-linear nature of the system equations. In this work, the physical concept of maximum relative acceleration of a machine at a fault scenario is related with the boundary of stability region. This approach is extended to develop a quadratic Lyapunov function using singular perturbed modelling. Unlike the conventional energy function methods, this Lyapunov function candidate is a more general energy function and has a decaying nature around an equilibrium point. Moreover, with higher order corrections, an improved Lyapunov function candidate is presented with simulation results of power system examples. The decaying nature of Lyapunov function candidate remains similar even without higher order corrections. However, the relevance of inclusion of higher order corrections is brought out in the cases of faults occurring at other than generator buses. Also, the upper bound of singular perturbation parameter in the model is within allowable limits and ensures the accuracy of results.

Adaptive Fuzzy Type-2 Synergetic Control Based on Bat Optimization for Multi-Machine Power System Stabilizers

Adaptive Fuzzy Type-2 Synergetic Control Based on Bat Optimization for Multi-Machine Power System Stabilizers

Adaptive Fuzzy Type-2 Synergetic Control Based on Bat Optimization for Multi-Machine Power System Stabilizers

A new, adaptive, fuzzy type-2 fast terminal, synergetic multi-machine power system stabilizer is proposed in this study, based on the Bat algorithm. The time spent to reach the equilibrium point, from any initial state, is guaranteed to be finite. The adaptive fuzzy type-2 design is applied to estimate the unknown functions of a multi-machine power system. The parameters of the fast terminal synergetic control are optimized, using bat metaheuristic method. In order to test the robustness of the proposed stabilizer, three load conditions, of the multi-machine power system are studied. A comparison of the proposed adaptive fuzzy type-2 synergetic power system stabilizer with bat conventional approach is presented, indicating improved performance. The control system stability is assessed by the second theorem of Lyapunov and is proven to be asymptotically stable.

A Coordinated Controller Design for DFIG-Based Multi-Machine Power Systems

This paper proposes a novel framework that enables the simultaneous coordination of the controllers of doubly-fed induction generators, synchronous generators, and static compensator devices. The proposed adaptive zero dynamics based approach aims at enhancing the transient stability and improving the voltage regulation of multi-machine power systems under a wide range of operating conditions. The proposed approach was implemented to Kundur's four-machine two-area and the IEEE 39-bus power systems. Its performance was assessed in the presence of various faulty scenarios and disturbances. Eigen-value analysis, time domain simulations, and transient stability margin analysis (measured by critical clearing time) were carried out in the performance assessment. Comparison analysis with other control approaches was also conducted to highlight the effectiveness of the proposed approach. Enhancing the power and voltage stability of large scale multi-machine power systems, damping inter-area power oscillations, and providing faster post-fault recovery time are among the positive features of the proposed approach.

ANN Based SVC FACTS Controller to Enhance Voltage Stability of Multi-Machine Power System

Voltage stability is the most vital phenomena in power systems which may be disturbed by the mismatch between the reactive power supply and demand. The occurrence of internal faults in the equipment and short circuit faults also there may be voltage collapse at the buses. Voltage stability can be improved using Static VAR Compensator (SVC) which is a shunt device. It can generate or absorb reactive power in a controlled manner such that it can enhance voltage stability of the system. L- Index method is used to determine voltage sensitivity at each bus and the bus having highest L- index value can be considered as a weak bus which is the optimal location of FACTS controller. The investigation is made to observe how susceptance in susceptance model and firing angle in firing angle model of the SVC is predicted to enhance the voltage at each bus by the artificial neural network under chaotic load. Standard IEEE 5 bus and 30 bus systems are considered as test systems and simulations are performed in MATLAB software.

A Sufficient and Necessary Condition of Transient Stability for Multimachine Systems

This paper presents a sufficient and necessary condition for transient stability of multimachine power systems based on the passivity formalism. The condition derived using the extended classical model (ECM) with zero transfer conductance (TC). The ECM of power systems relaxes slightly the assumption of “voltage-behind-transient-reactance” from “constant”, which is used in the conventional classical model to “positive, bounded and independent of machine rotor angles”. The results of time domain simulation of a full model of Western Interconnection used for regular operation planning study are presented for verifying the model assumptions and the storage functions of the system in four different scenarios (well stable, marginally stable, marginally unstable and very unstable), thus illustrating the sufficiency and necessity of stability criterion based on passivity.

Interconnected multi-machine power system stabilizer design using whale optimization algorithm

The role of Power System Stabilizer (PSS) in the power system is to provide necessary damping torque to the system in order to suppress the oscillations caused by a variety of disturbances that occur frequently and maintain the stability of the system. In this paper, a PSS design technique is proposed using Whale Optimization Algorithm (WOA) by considering eigenvalue objective function. Two bench mark multi machine test systems: three- generator nine- bus system, two- area four- generator inter connected system working on various operating conditions are considered as case studies and tested with the proposed technique. Extensive simulation results are obtained and effectiveness of proposed WOA-PSS are compared with well - known PSO and DE based stabilizers under several disturbances.

A coordinated control for voltage and transient stability of multi-machine power grids relying on wind energy

This paper proposes a new nonlinear control approach to coordinate doubly fed induction generator (DFIG)-based wind turbines and static synchronous compensator (STATCOM) controllers in multi-machine power systems. Its main objectives are to improve the transient and voltage stability of the inter-connected multi-machine power system via simultaneous design of the voltage of the DFIGs’ rotors and reference current of STATCOM. The nonlinear approach is based on a multi input-multi output (MIMO) zero dynamics (ZD) technique augmented by a super twisting sliding mode control (STSMC) to reduce the effects of the linearization error. The proposed approach was implemented to the Kundur’s four-machine two-area power system and the IEEE 39-bus power system. Its performance was assessed in the presence of various faulty scenarios and disturbances. The effectiveness of the proposed approach (ZD-STSMC) was evaluated via eigenvalue analysis, transient simulations and transient stability margin analysis (by critical clearing time (CCT)). The merits of the proposed design are further compared to those of the exact feedback linearization (EFL) approach. Enhancing the power and voltage stability of large scale power systems, damping power oscillations and providing faster post-fault recovery time are among the positive features of the proposed approach.

Improved model for investigating transient stability in multimachine power systems

<span>The determinant factor in transient stability study of electric power systems is the behavior of synchronous generators when subjected to sudden and large disturbances. The objective of this paper is to develop a mathematical model, general algorithm, and a computer program to investigate the transient stability of multi-machine power systems. The developed mathematical model is established as a first step. The new developments lie in modeling the fault occurrence and fault clearance as well as the procedure of computing the system matrices during and after the fault through only modification of the matrix before the fault. Based on the developed mathematical model, a general algorithm was built and translated into a computer program using an object-oriented and visual language called Delphi. The algorithm adopted the Runge-Kutta method for numerical solution of differential swing equations and was programmed within the program. The developed program was validated by applying it to small sample electrical networks. The program was used to analyze the transient stability of a relatively large test network and accurate results were obtained that could be relied upon for protective relays settings and optimization of control system parameters. It was found that the developed program is an effective and rapid tool for estimating transitory stability for real power systems.</span>

Comprehensive review on enhancement of stability in multimachine power system with conventional and distributed generations

A comprehensive review on stability analysis in multimachine power system is presented in this study. The increasing demand of power has led to the expansion of power system and complexity in design as well as operation. This threatens to deteriorate the stability and reliability in the power network. However, with the advances in semiconductor and power electronic control technology, various flexible AC transmission systems (FACTS) are designed to enhance the power system stability. Different power system configurations with the incorporation of conventional and distributed generations (DGs) are proposed whose stability is being tested in the presence of the FACTS controllers. The optimal damping of power system oscillations under transient operating conditions are studied in presence of HVAC and HVDC links with conventional as well as DG systems and energy storage options like battery, supercapacitors and so on. Different control approaches such as classical control, robust control, wide-area control along with soft computing approaches like neural networks, fuzzy logic control, adaptive neuro-fuzzy inference system, genetic algorithm, particle swarm optimisation and so on are broadly discussed. A comparative analysis of different methodologies is presented to establish a quick survey of the proposed solutions for stability enhancement.

Improvement of multi-machine power system stability using artificial intelligent power system stabilizer

Improvement of multi-machine power system stability using artificial intelligent power system stabilizer

Multi-machine optimal power system stabilizers design based on system stability and nonlinearity indices using Hyper-Spherical Search method

Design of power system stabilizer (PSS) withstanding critical situations is a challenging task. In this paper, an effective method for the design of a coordinated multiple PSS in power systems are offered and weaknesses of the existing methods are disclosed. The setup includes the nonlinear model of the system, a specific multi-objective function and a newly developed meta-heuristic Hyper-Spherical Search (HSS) optimization algorithm. The objective function includes both eigenvalue stability index (SI) and nonlinearity index (NI). The employed new NI is the second order modal interaction of the lightly damped electromechanical modes. The performance of the proposed Stability-Nonlinearity index (SN) based PSS design by HSS (SNPSS-HSS) is compared with SNPSS-GA, SI based PSS (SPSS) and the conventional design method (CPSS) under various operating conditions and disturbances. The investigations are conducted over both a single lead PSS and PSS2B. The performance is detailed using time domain simulations, SI and NI analysis. A four-machine two-area system and the IEEE 39-bus system are utilized for test purpose. The results of extensive simulations indicate the superiority of SNPSS-HSS design with respect to the others. The obtained relative stability is higher and the nonlinearity index is lower than the product of the other designs. Besides, as it is expected, using a high degree of freedom PSS2B improves the performance of the aforementioned algorithms.