Theory and method for selection of power system stabilizer location

An approach for the selection of best PSS (power system stabilizer) locations in multimachine power systems is proposed. Study shows that the right-eigenvector measures the activity of state variables and the left-eigenvector measures the control effect of control signals. Based on the right and left eigenvector, the concept of sensitivity of PSS effect (SPE) is presented and used to identify the best PSS locations. The method is used to identify the best PSS location is a 13-machine system to increase the damping of an interarea mode. The time-domain simulation results confirm that the prediction of the best PSS location by the SPE method is correct and accurate     

Transient excitation boosting at Grand Coulee Third Powerplant

The design, installation, testing, and operating experience of a transient excitation boosting (TEB) system at Grand Coulee Third Powerplant on the Columbia River in Washington state is described. The installed TEB system provides significant reactive power support to the northwest power system from this 4000 MVA hydroelectric powerplant. A microprocessor-based TEB module that interfaces to existing solid-state regulators on the six Third Powerplant generators and physically fits into the limited space available was designed. Redundancy, fail-safe circuitry, and complete status indication and alarms were designed into the TEB system from the start. Installation of the TEB system involved significant changes to the regulator wiring. Also significant were the amounts of control cabling and wiring changes needed in the existing plant control systems. Power system stabilizer (PSS) control system changes were necessary to make TEB and PSS control philosophies similar     

Optimal design of power-system stabilizers using particle swarm optimization

In this paper, a novel evolutionary algorithm-based approach to optimal design of multimachine power-system stabilizers (PSSs) is proposed. The proposed approach employs a particle-swarm-optimization (PSO) technique to search for optimal settings of PSS parameters. Two eigenvalue-based objective functions to enhance system damping of electromechanical modes are considered. The robustness of the proposed approach to the initial guess is demonstrated. The performance of the proposed PSO-based PSS (PSOPSS) under different disturbances, loading conditions, and system configurations is tested and examined for different multimachine power systems. Eigenvalue analysis and nonlinear simulation results show the effectiveness of the proposed PSOPSSs to damp out the local and interarea modes of oscillations and work effectively over a wide range of loading conditions and system configurations. In addition, the potential and superiority of the proposed approach over the conventional approaches is demonstrated.     

Robust design of multimachine power system stabilizers usingsimulated annealing

Robust design of multimachine power system stabilizers (PSSs) using simulated annealing (SA) optimization technique is presented in this paper. The proposed approach employs SA to search for optimal parameter settings of a widely used conventional fixed-structure lead-lag PSS (CPSS). The parameters of the proposed simulated annealing based power system stabilizer (SAPSS) are optimized in order to shift the system electromechanical modes at different loading conditions and system configurations simultaneously to the left in the s-plane. Incorporation of SA as a derivative-free optimization technique in PSS design significantly reduces the computational burden. One of the main advantages of the proposed approach is its robustness to the initial parameter settings. In addition, the quality of the optimal solution does not rely on the initial guess. The performance of the proposed SAPSS under different disturbances and loading conditions is investigated for two multimachine power systems. The eigenvalue analysis and the nonlinear simulation results show the effectiveness of the proposed SAPSS's to damp out the local as well as the interarea modes and enhance greatly the system stability over a wide range of loading conditions and system configurations     

励磁调节对水力发电机组过渡过程的影响分析

为深入研究励磁调节对水力发电机组过渡过程的影响,在Matlab/Simulink平台上,采用面向对象的程序设计技术,建立了包括水力、机械及电气部分的联合计算模型,研究了机组并入不同容量的电力系统时,励磁调节和电力系统稳定器(PSS)对机组频率波动特性和水力过渡过程的影响。计算结果表明,在有限容量的电力系统中,机组安装励磁调节和PSS除了能有效地对无功功率和电压进行调节之外,对机组频率波动也有良好的改善作用,对调压室水位波动有一定的抑制作用,有利于提高电能质量。     

The modal performance measure for parameter optimization of powersystem stabilizers

This paper develops an optimization approach using the modal performance measure for the selection of power system stabilizer (PSS) parameters in multimachine power systems. The goal of the optimization problem is to damp out the sustained low frequency oscillations in the outputs of a linearized power system. Thus, the modal performance measure optimization problem is to select a set of PSS parameters so that the area under the envelop of the oscillatory output response will be minimum. This paper also considers bounded and unbounded PSS parameters and compares the effects of bounds on the end results. Furthermore, this work also shows that the performance measure is not a convex function in the PSS parameters. That is, there exist many local minima and possibly a global minimum. Single-machine infinite-bus and two-machine three-bus power systems are used to show the effectiveness of the proposed work     

Design of augmented fuzzy logic power system stabilizers to enhancepower systems stability

This paper presents an augmented fuzzy logic power system stabilizer (PSS) for stability enhancement of multimachine power systems. In order to accomplish a satisfactory damping characteristic over a wide range of operating points, speed deviation (Δω) and acceleration (Δω) of a synchronous generator were taken as the input signals to the fuzzy controller. It is well known that these variables have significant effects on damping the generators' shaft mechanical oscillations. A modification of the terminal voltage feedback signal to the excitation system as a function of the accelerating power on the unit, is also used to enhance the stability of the system. The stabilizing signals are computed using the standard fuzzy membership function depending on these variables. The performance of the proposed augmented fuzzy controller is compared to an optimal controller and its effectiveness is demonstrated by a detailed digital computer simulation of a single machine infinite bus and a multimachine power systems     

PSS performance as affected by its output limiter

The effects of control limits of power system stabilizers (PSS) have been studied using the Transient Stability Simulation Package (TSSP) and a real-time simulator. Extensive simulations were carried out for three different power systems with PSSs using either electrical power or speed deviation as input signal. Results from batch and real-time simulations are in agreement with each other for the cases studied. It has been concluded that higher PSS output limit settings can achieve added damping and enhance transient stability. They yield excellent PSS performance during major system disturbances     

Generalized one-machine equivalents in transient stability studies

We consider an emerging class of hybrid methods which basically reduce a multimachine power system into a one-machine infinite bus (OMIB) equivalent and then apply the suitably adapted equal-area criterion. A time-domain transient stability program is used to refresh the OMIB parameters at each time step to arrive at “generalized” OMIBs. The scheme is able to provide accurate real-time transient stability assessment under any power system modeling, any stability scenario and any instability mode. On the other hand, similar generalized OMIBs may potentially be designed for real-time transient stability emergency control, by using real-time measurements. The purpose of this letter is to highlight some unique enhancements to the class of methods offered by the generalized OMIB concept     

Optimal design of power system stabilizers using evolutionary programming

The optimal design of power system stabilizers (PSSs) using evolutionary programming (EP) optimization technique is presented in this paper. The proposed approach employs EP to search for optimal settings of PSS parameters that shift the system eigenvalues associated with the electromechanical modes to the left in the s-plane. Incorporation of EP algorithm in the design of PSSs significantly reduces the computational burden. The performance of the proposed PSSs under different disturbances, loading conditions, and system configurations is investigated for a multimachine power system. The eigenvalue analysis and the nonlinear simulation results show the effectiveness and robustness of the proposed PSSs to damp out the local as well as the interarea modes of oscillations and work effectively over a wide range of loading conditions and system configurations.     

Design of Decentralized Multivariable Excitation Controllers in Multimachine Power Systems by Projective Controls

A methodology for the design of decentralized multivariable excitation controllers in multimachine power systems is developed using projective controls. The existing methodology, is extended to permit the coordinated design of AVR and PSS controllers in power systems.     

Nonlinear Decentralized Disturbance Attenuation Excitation Control for Power Systems With Nonlinear Loads Based on the Hamiltonian Theory

A novel nonlinear control scheme for disturbance attenuation of structure preserving multimachine power systems based on Hamiltonian theory is proposed in this paper. The proposed control scheme includes two steps: first, the dissipative Hamiltonian realization of structure preserving power system is completed using the singular perturbation approach in which the algebraic equations are considered as a limit of fast dynamics; second, a nonlinear decentralized disturbance attenuation excitation controller is designed without linearization to improve transient stability of power system as well as the robustness with respect to unknown exogenous disturbance in the sense of L₂-gain. Simulation on a two-area system demonstrates that the proposed scheme can enhance transient stability of the system regardless of the exogenous disturbance.     

超导储能系统提高风电场暂态稳定性研究

应用超导储能系统(SMES)对提高风电场的暂态稳定性进行了研究。在深入研究超导储能系统运行原理的基础上,建立了基于电压型换流器(VSC)的超导储能系统模型,实现了有功功率和无功功率的解耦控制,并提出了有功、无功功率综合控制策略。利用PSCAD/EMTDC软件进行了仿真计算,结果说明超导储能系统不但能够在风速波动时平滑风电场的功率输出,而且能够提高风电系统的暂态稳定性。     

Neural network-based self-organizing fuzzy controller for transientstability of multimachine power systems

An efficient self-organizing neural fuzzy controller (SONFC) is designed to improve the transient stability of multimachine power systems. First, an artificial neural network (ANN)-based model is introduced for fuzzy logic control. The characteristic rules and their membership functions of fuzzy systems are represented as the processing nodes in the ANN model. With the excellent learning capability inherent in the ANN, the traditional heuristic fuzzy control rules and input/output fuzzy membership functions can be optimally tuned from training examples by the backpropagation learning algorithm. Considerable rule-matching times of the inference engine in the traditional fuzzy system can be saved. To illustrate the performance and usefulness of the SONFC, comparative studies with a bang-bang controller are performed on the 34-generator Taipower system with rather encouraging results     

Stability of a multi-machine system incorporating a superconductingalternator

A preliminary study on the transient behavior of a superconducting turbo-alternator in a typical multimachine system is described. The study covers the effect of conventional controllers, power-system stabilizers and phase advance networks. The open-loop response of the system is compared to the response when the superconducting alternator is replaced by its conventional counterpart     

Power system output feedback stabilizer design via optimal subeigenstructure assignment

The paper addresses the design of a power system stabilizer using an optimal reduced order model whose state variables are torque angles and speeds. System damping can be improved using eigenvalue assignment, and the co-ordination of stabilizers can be achieved through eigenvector assignment by maintaining system mode shape. The proportional-integral PSS is derived via the optimal reduced order model instead of via the whole system model. The effectiveness of this stabilizer is evaluated, and this study reveals that the result of eigenstructure assignment is more stable and much better than in the assignment method based on the whole system model. A one-machine infinite-bus system and a multimachine system are given as examples to illustrate the advantages and effectiveness of the proposed approach. Results based on the whole system model are included for comparison.     

Influence of Tower Shadow and Wind Turbulence on the Performance of Power System Stabilizers for DFIG-Based Wind Farms

The aim of the paper is to demonstrate the way in which mechanical power variations, due to tower shadow and wind turbulence, influence control performance of power system stabilizer (PSS) loops for doubly-fed induction generators (DFIGs). The PSS auxiliary loops are applied on a specific DFIG control scheme, the flux magnitude and angle controller (FMAC). However, since the PSS signal is applied at the output of the basic controller, the PSS performance characteristics displayed are deemed typical for DFIG control schemes in general. The relative capabilities of PSS controllers based on stator power, rotor speed, and network frequency, when the DFIG turbine is subjected to aerodynamic torque variations, are investigated via simulation studies. A two-generator aggregate model of a wind farm is introduced, which enables the influence of tower shadow and wind turbulence on both an individual turbine and on the overall wind farm itself to be assessed.     

汽油机点火系统自适应控制的瞬态响应及稳定性

本文介绍了自适应控制点火系统瞬态特性的测量枝术、试验结果及其改进方法。当发动机急变速时,建议将自适应控制转为传统分电器控制,以改进瞬态响应的性能。而自适应控制的稳定性和灵敏度则可用合适的屏蔽方法得到满意的协调。     

A robust H∞ power system stabilizer with noadverse effect on shaft torsional modes

The H^∞ optimal control theory has been used to design a robust power system stabilizer (PSS) to improve transient and dynamic stabilities of a turbogenerator connected to an infinite busbar. It is demonstrated that the effects of disturbances in the machine output can be minimized and sufficient closed-loop stability margins (robustness) can be obtained to tolerate variations in the loop transfer functions, such as those which might arise from unmodeled low-damped high-frequency modes of oscillations. The resulting controller would effectively enhance the synchronizing and damping torques of the machine without the risk of exciting the shaft torsional modes. This is in marked contrast with the unstable performance of linear quadratic (LQ) optimal controllers under similar conditions. The H^∞ design methodology also ensures a satisfactory performance of the PSS under a wide range of system operating conditions     

A comparison of rotor damping from adaptive and conventional PSS ina multi-machine power system

A comparison between damping available from a conventional power system stabilizer (PSS) and an adaptive controller is made using a transient stability program simulation of a nine-machine power system. A step change to terminal voltage and variable duration bus faults is used for network disturbances to illustrate the added damping available from the adaptive PSS. Simulation results showing the relative damping contributions of the two stabilizers are presented