Three-dimensional power system stabilizer

Power system stabilizers (PSSs) are used to enhance damping of power system oscillations through excitation control of synchronous generator. The objective of the PSS is to generate a stabilizing signal, which produces a damping torque component on the generator shaft. Conventional PSSs are designed with the phase compensation technique in the frequency domain and include the lead-lag blocks whose parameters are determined according to a linearized power system model. The performance of conventional PSSs (CPSSs) depends upon the generator operating point and the system parameters, but a reasonable level of robustness can be achieved depending on the tuning method. This paper presents a new three-dimensional PSS (3D PSS), which uses rotor speed deviation, rotor acceleration and load angle deviation as input signals. The 3D PSS attempts to return the generator to the state-space origin, based on the generator’s trajectory in state-space and the achievement of torque equilibrium. The 3D PSS is robust to system parameters changes. The proposed algorithm was implemented in a digital control system, tested in a laboratory environment on a synchronous generator connected to the power system, and then compared with CPSS. Experimental results show that the proposed PSS achieves better performance than the CPSS in damping oscillations.     

灰色预测励磁控制同步发电机动态过程仿真

为了更准确地研究灰色预测励磁控制对发电机行为的影响,基于非线性派克模型构建了考虑PSS作用的同步发电机灰色预测励磁控制系统模型,并以单机无穷大系统为对象对其控制效果进行了仿真。与采用线性化模型相比,采用非线性派克模型可保证灰色预测控制输入数据的非负性,简化预测算法。考虑调速系统和PSS的作用后,能更加准确和全面的了解灰色预测励磁控制系统的控制效果。仿真结果表明,在大小扰动下,无论是否具有PSS,同步发电机励磁系统中引入灰色预测控制后均可明显地改善系统的稳定性。     

采用协同控制理论的同步发电机非线性励磁控制

提出了一种基于协同控制理论的非线性励磁控制器。首先依据同步发电机励磁控制的基本要求和特点,选择机端电压、有功功率和转子角速度三个变量的偏差的线性组合构成流形,以保证有效控制机端电压和抑制系统功率振荡。然后以同步发电机非线性模型为对象,推导出了非线性协同励磁控制器（Synergetic excitation controller,SEC）的控制律,并根据电力系统的运行特性,探讨了控制器参数的选取原则。最后,单机无穷大系统仿真结果表明,无论在大扰动还是在小扰动下,所提非线性协同励磁控制器比常规的AVR+PSS方式下的励磁控制器都能更快更精确地调节机端电压,还能够有效地抑制系统的功率振荡。     

Pole placement technique for PSS and TCSC-based stabilizer design using simulated annealing

A pole placement technique for power system stabilizer (PSS) and thyristor controlled series capacitor (TCSC) based stabilizer using simulated annealing (SA) algorithm is presented in this paper. The proposed approach employs SA optimization technique to PSS (SAPSS) and TCSC-based stabilizer (SACSC) design. The design problem is formulated as an optimization problem where SA is applied to search for the optimal setting of the proposed SAPSS and SACSC parameters. A pole placement-based objective function to shift the dominant eigenvalues to the left in the s-plane is considered. The proposed SAPSS and SACSC have been examined on a weakly connected power system with different disturbances, loading conditions, and system parameter variations. Eigenvalue analysis and nonlinear simulation results show the effectiveness and the robustness of the proposed stabilizers and their ability to provide efficient damping of low frequency oscillations. In addition, the performance of the proposed stabilizers outperforms that of the conventional power system stabilizer (CPSS). It is also observed that the proposed SACSC improves greatly the voltage profile of the system under severe disturbances.     

Design of a nonlinear power system stabilizer using synergetic control theory

Electromechanical oscillations of small magnitude and low frequency exist in the interconnected power system and often persist for long periods of time. Power system stabilizers (PSSs) are traditionally used to provide damping torque for the synchronous generators to suppress the oscillations by generating supplementary control signals for the generator excitation system. Numerous techniques have previously been proposed to design PSSs but many of them are synthesized based on a linearized model. This paper presents a nonlinear power system stabilizer based on synergetic control theory. Synergetic synthesis of the PSS is based fully on a simplified nonlinear model of the power system. The dynamic characteristics of the proposed PSS are studied in a typical single-machine infinite-bus power system and compared with the cases with a conventional PSS and without a PSS. Simulation results show the proposed PSS is robust for such nonlinear dynamic system and achieves better performance than the conventional PSS in damping oscillations.     

A new SPARLS algorithm for tuning power system stabilizer

Generators have to meet the change in real and reactive power demand of practical power system. The real power variations in the system are met out by the rescheduling process of the generators. But there is a huge trust to meet out the reactive power load demand. The excitation loop of the corresponding generator is adjusted with its electric limits to activate the reactive power of the network. To expedite the reactive power delivery, power system stabilizer (PSS) is connected in the exciter loop of the generator for various system conditions. In this paper, a new Sparse Recursive Least Square (SPARLS) algorithm is demonstrated to tune the power system stabilizer parameters to meet the vulnerable conditions. The proposed SPARLS algorithm makes use of expectation maximization (EM) updation to tune the PSS. A comparative study between the proposed SPARLS and RLS algorithm has been performed on single machine infinite bus system (SMIB). The simulation results obtained will validate the effectiveness of the proposed algorithm and the impact of stability studies of the power system operation under disturbances. The SPARLS algorithm is also used to tune the parameters of PSS to achieve quicker settling time for the system parameter such as load angle, field voltage and speed deviation. It is found that the SPARLS is a better algorithm for the determination of optimum stabilizer parameter.     

An online adaptive neuro-fuzzy power system stabilizer for multimachine systems

A fuzzy-logic-based adaptive power system stabilizer (PSS) is proposed in this paper. The parameters of the fuzzy-logic-based PSS are tuned by neural networks online. The system is divided into two subsystems, a recursive least square identifier with a variable forgetting factor for the generator and a fuzzy-logic-based adaptive controller to damp oscillations. The effectiveness of the proposed PSS in increasing the damping of local and inter-area modes of oscillation is demonstrated in a one-machine-infinite-bus system; a two-area, 4-machine, 13-bus system, and a 16-machine, 68-bus system.     

Stabilization control of multi‐machine power systems by adaptive power system stabilizer using frequency domain analysis

To improve electric power system transient stability, synchronous generators are generally equipped with controllers such as AVR, PSS, and GOV. Fixed parameter controllers degrade control performance, since various oscillation modes occur depending on system conditions. This paper presents an adaptive power system stabilizer (PSS) using frequency domain analysis for improving the transient stability of a multimachine system. In the proposed method, first, the frequency components of the generator swings are detected by the FFT. The conventional PSS parameters are tuned online by a fuzzy controller and frequency domain analysis. We verify the proposed adaptive PSS using frequency domain analysis, which can damp the generator swings effectively. © 2002 Wiley Periodicals, Inc. Electr Eng Jpn, 142(2): 10–20, 2003; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.10129     

同步发电机-电力电子变压器组的最优协调控制

电力电子变压器(PET)是一种通过电力电子变换实现电力系统电压变换和能量传递的新型变压器.文章研究了电力系统中发电机-PET组的协调控制问题,首先建立了由发电机-PET组构成的电力系统数学模型,然后应用最优控制理论,提出了一种发电机-PET组的最优协调控制器.该控制器中的控制量分别为发电机励磁电压、PET一次侧和二次侧的电压源变换器中的脉宽调制的调制度和相角,反馈量则为发电机的功角、角速度、机端电压以及PET的直流环节电压.仿真结果表明,与由常规发变组构成的系统相比,该最优协调控制器有效地提高了扰动条件下的系统阻尼,同时改善了系统的电压特性.     

Robust PID based power system stabiliser: Design and real-time implementation

This paper addresses a new robust control strategy to synthesis of robust proportional-integral-derivative (PID) based power system stabilisers (PSS). The PID based PSS design problem is reduced to find an optimal gain vector via an H∞ static output feedback control (H∞-SOF) technique, and the solution is easily carried out using a developed iterative linear matrix inequalities algorithm. To illustrate the developed approach, a real-time experiment has been performed for a longitudinal four-machine infinite-bus system using the Analog Power System Simulator at the Research Laboratory of the Kyushu Electric Power Company. The results of the proposed control strategy are compared with full-order H∞ and conventional PSS designs. The robust PSS is shown to maintain the robust performance and minimise the effect of disturbances properly.     

具有多模型适应性的发电机PSS参数优化方法

现代电力系统中应用配置的电力系统稳定器(PSS)模型不尽相同,而传统PSS参数设计方法仅局限于传统PSS模型。文中提出了具有多模型适应性的发电机PSS参数优化方法,以PSS相位补偿效果为优化目标,采用粒子群算法对该发电机的PSS参数进行优化。该方法对多种PSS模型具有高度适应性,不仅适用于传统的PSS模型,也适用于无超前滞后环节的新型PSS模型。算例表明,采用具有多模型适应性的发电机PSS参数优化方法可有效提升系统阻尼,抑制系统低频振荡。     

Robust decentralized multi-machine power system stabilizer design using quantitative feedback theory

A new robust power system stabilizer (PSS) design using Quantitative Feedback Theory (QFT) for damping electromechanical modes of oscillations and enhancing power system stability is proposed in this paper. The design procedure is carried out on a multi-input–multi-output (MIMO), non-minimum phase and unstable plant. A multi-machine electric power system with system parametric uncertainties is considered as a case study. To show the effectiveness of the QFT technique, the proposed method is compared with a conventional PSS (CPSS) whose parameters are tuned using the classical lead-lag compensation and genetic algorithms. Several nonlinear time-domain simulation tests indicate that the suggested control scheme is robust to the changes in the system parameters and also to successfully reject the disturbances. The results also show that the performance of the QFT method given in this paper is more desirable than CPSS and genetic algorithm (GA).     

A hybrid neuro-fuzzy power system stabilizer for multimachine powersystems

A fuzzy basis function network (FBFN) based power system stabilizer (PSS) is presented in this paper to improve power system dynamic stability. The proposed FBFN based PSS provides a natural framework for combining numerical and linguistic information in a uniform fashion. The proposed FBFN is trained over a wide range of operating conditions in order to re-tune the PSS parameters in real-time based on machine loading conditions. The orthogonal least squares (OLS) learning algorithm is developed for designing an adequate and parsimonious FBFN model. Time domain simulations of a single machine infinite bus system and a multimachine power system subject to major disturbances are investigated. The performance of the proposed FBFN PSS is compared with that of conventional (CPSS). The results show the capability of the proposed FBFN PSS to enhance the system damping of local modes of oscillations over a wide range of operating conditions. The decentralized nature of the proposed FBFN PSS makes it easy to install and tune     

A fuzzy basis function network based power system stabilizer for generator excitation control

A fuzzy basis function network (FBFN) based power system stabilizer (PSS) is presented in this paper. The proposed FBFN-based PSS provides a natural framework for combining numerical and linguistic information in a uniform fashion. The proposed FBFN is trained over a wide range of operating conditions in order to retune the PSS parameters in real-time, based on machine loading conditions. The orthogonal least squares (OLS) learning algorithm is developed for designing an adequate and parsimonious FBFN model. Time domain simulations of a synchronous machine equipped with the proposed stabilizer subject to major disturbances are investigated. The performance of the proposed FBFN PSS is compared with that of a conventional power system stabilizer (CPSS) to demonstrate the superiority of the proposed stabilizer. The effect of parameter changes on the proposed stabilizer performance is also examined. The results show the robustness of the proposed FBFN PSS and its capability to enhance system damping over a wide range of operating conditions.     

新型外挂式电力系统稳定器装置的设计与实现

针对电网对发电机励磁系统配置电力系统稳定器的应用要求,分析了电力系统稳定器(power system stabilizer,PSS)装置功能需求,提出一种以Power PC+DSP为控制核心的新型外挂式电力系统稳定器装置。阐述了装置的软硬件设计方案,提出了一种发电机转子转速实时快速测量方法,通过动模仿真试验验证了装置设计的实用性和功能的正确性。该装置提供了一种通过外加装置实现励磁系统PSS功能改造、升级的途径,能够增强投运机组抑制系统有功低频振荡的能力,提高电网的稳定裕度。     

A comparative study of damping schemes on damping generatoroscillations

Results of a comparative study of the application of three different compensators, the power system stabilizer (PSS), the static VAR compensator (SVC), and the rectifier current regulator (RCR), for the damping enhancement of generator oscillations in a power system are presented. In order to enhance the dampings of both the mechanical mode and the exciter mode in the system, a unified approach based on modal control theory is proposed for the design of the PSS, the SVC, and the RCR. A proportional-integral-derivative (PID) type controller using generator speed deviation as a modulated signal to generate the desired damping is proposed, and it is shown that both affected system modes can be exactly located at the prespecified positions on the complex plane by the proposed damping schemes. To demonstrate the effectiveness of the proposed PID controllers and their relative merits, a frequency-domain study based on eigenvalue analysis under different operating conditions and a time-domain study based on nonlinear model simulations under disturbance conditions are performed     

Multi-machine power system stabilizer design by rule based bacteria foraging

Several power system stabilizers (PSS) connected in number of machines in a multi-machine power systems, pose the problem of appropriate tuning of their parameters so that overall system dynamic stability can be improved in a robust way. Based on the foraging behavior of Escherichia coli bacteria in human intestine, this paper attempts to optimize simultaneously three constants each of several PSS present in a multi-machine power system. The tuning is done taking an objective function that incorporates a multi-operative condition, consisting of nominal and various changed conditions, into it. The convergence with the proposed rule based bacteria foraging (RBBF) optimization technique is superior to the conventional and genetic algorithm (GA) techniques. Robustness of tuning with the proposed method was verified, with transient stability analysis of the system by time domain simulations subjecting the power system to different types of disturbances.     

发电机阻尼与电力系统稳定器试验——发电机负载阶跃响应

通过实例介绍了发电机励磁系统带有附加反馈控制及无附加反馈时对低频振荡阻尼的试验方法,比较了各种现场试验,表明发电机负载阶跃响应是最简捷的检查PSS效果及调整PSS参数的方法。文中提出了弱阻尼界定的初步意见,并说明计算弱阻尼时应考虑发电机组的阻尼系统。     

电力系统扰动后稳态频率预测快速算法

研究了基于广域量测系统的电力系统频率稳定分析直接法的精度和复杂度,提出了电力系统扰动后稳态频率预测快速算法。利用电力系统仿真软件PSS/E对IEEE50机改进测试系统进行了仿真试验,比较了不同负荷模型方案对系统扰动后稳态频率的影响。通过蒙特卡洛法求解实现了所提出的快速算法,它利用扰动后瞬间的广域量测数据,快速预测出系统扰动后的稳态频率。预测的稳态频率与PSS/E仿真得到稳态频率相比很接近,表明该快速算法求解速度快,精度高。     

基于仿真软件PSS/E的低频振荡分析方法

基于仿真软件PSS/E提出了一种分析华东电网低频振荡特性的方法,结合PSS/E的特征值分析法和Prony分析法,在发电机采用经典模型的条件下通过特征值分析计算系统振荡模式的频率、振型和参与因子,而在发电机采用详细模型并考虑励磁系统详细模型的条件下通过Prony分析法计算系统振荡模式的阻尼。对4机两区域系统和新英格兰10机39节点系统的特征值分析表明,振荡模式的频率、振型和参与因子并不随发电机采用模型的不同而有很大变化。因此,文中提出的方法可以方便地适用于实际大规模电力系统的低频振荡分析。对华东电网的低频振荡特性进行分析,得到了该电网区域间振荡模式的频率、阻尼、振型及参与因子。