Design of robust coordinated SVC supplementary controllers

A method for designing coordinated H_∞ SVC supplementary controllers is presented to improve the damping of interarea oscillations. A distributed controllers are designed considering overvoltage problem, which is thought to be a critical issue for SVC to design a supplementary damping controller. The proposed method contains a method to obtain dynamic equivalents of a power system model through an uncertainty minimization procedure. This method is aimed for realizing a tight design for distributed controllers so that a better performance of the total system can be gained. In addition, an uncertainty minimization process is used to regulate indirectly the controller's output so that the overvoltage problem is treated in the design step. The locations of SVCs are determined from the voltage stability point of view using bus participation factor. An effective input to damp oscillations is selected based on residue concept. The effectiveness of the proposed control design is demonstrated through nonlinear numerical simulations in five machine eight bus system under several critical operating conditions.     

多FACTS广域抗时滞协调控制

提出一种基于自由权矩阵方法的多灵活交流输电系统(FACTS)抗时滞协调控制算法。该算法采用广域测量系统(WAMS)的输出反馈信号,考虑信号的传输时滞,使用自由权矩阵时滞稳定定理作为判据,同时保证时滞系统的最小阻尼比在一定阈值之上,利用量子遗传算法寻优获得多FACTS协调控制器的最佳增益。2台静止无功补偿器(SVC)算例的时域仿真结果验证了所提算法的有效性。     

State estimation of power systems containing facts controllers

This paper proposes a practical approach to incorporate Flexible AC Transmission Systems (FACTS) devices into a Weighted Least Squares (WLS) state estimation algorithm. The FACTS devices included in the estimator are the Thyristor Controlled Series Compensator (TCSC), the Static Var Compensator (SVC), and the Unified Power Flow Controller (UPFC). The proposed approach simultaneously upgrades the estimated values of the state variables of these devices and the state variables of the rest of the electric network, for a unified solution in a single-frame of reference. Results are presented to demonstrate the effectiveness of the proposed approach to assess the estimation of the system state and to set the parameters of FACTS controllers for given control specifications.     

基于智能积分的多模协调控制交流伺服系统研究

为了满足交流伺服系统高精度、快响应的要求,结合模糊控制、比例控制和积分控制各自的优点,设计了一种基于智能积分的多模控制模糊控制器,并且分析了该控制策略的可行性,并将其应用于交流伺服系统.通过仿真和具体实验分别验证了上述分析和设计的合理性.试验结果表明:该控制方法不仅大大提高了交流伺服系统的稳态精度,缩短了过渡过程时间,加快了交流伺服系统的动态响应,而且对交流伺服系统有很好的抗干扰性能和较强的鲁棒性,使交流伺服系统具有较好的动、静态性能.     

Multi-area coordinated decentralized DC optimal power flow

This paper provides a framework to carry out a multi-area optimal power flow in a coordinated decentralized fashion. A DC nonlinear optimal power flow model is used. Losses are incorporated through additional loads based on cosine approximations. The model makes it possible the independent optimal dispatch of each area while the global economical optimum of the whole electric energy system is achieved. This is possible by means of the Lagrangian relaxation decomposition procedure. Optimal energy pricing rates for the energy traded through the interconnections are derived. The developed algorithm can be run in parallel either to carry out numerical simulations or in an actual multi-area electric energy system     

Dynamic ATC enhancement through optimal placement of FACTS controllers

Flexible AC Transmission System (FACTS) controllers offer an effective means to enhance the power transfer capability of the network. However, the extent to which a FACTS controller can enhance Available Transfer Capability (ATC) depends on its optimal location in the system. This paper has proposed sensitivity analysis of structure preserving energy margin with respect to the control parameters of FACTS controllers for their optimal placement in the network. Two types of FACTS controllers, viz. Static Synchronous Compensator (STATCOM) and Unified Power Flow Controllers (UPFC) have been considered. The hybrid approach, combining a structure preserving and a time domain simulation method, has been utilized to compute the dynamic ATC in presence of these controllers and their impact on dynamic ATC has been analyzed. The potential energy, contributed by the STATCOM and the UPFC, has also been included in the structure preserving energy function to include their influence on transient stability. The proposed method has been tested on 39-bus New England system and a practical 246-bus Indian system.     

Real-time gain tuning of PI controllers for high-performance PMSM drives

In this paper, a new and practical real-time gain-tuning method for proportional plus integral (PI) controllers has been formulated and implemented, using the speed control of a permanent-magnet synchronous motor drive system as a testbed. While the novel strategy enhances the performance of traditional PI controller greatly and proves to be a completely model-free approach, it also preserves the simple structure and features of PI controllers. The essential idea is as follows: (1) according to the system dynamics to step variation, define a performance index to evaluate the system response; (2) based on the monotonous relationship between the performance index and an intermediate PI gain parameter, this latter parameter is estimated with a modified binary search algorithm in order to improve the performance index; and (3) finally, PI gains are calculated and renewed according to the estimated intermediate gain parameter. Experiments have been thoroughly carried out to test the proposed method under different conditions. Besides being simple and easy to implement for real-time applications, the proposed method also possesses features such as versatility, stability, and effectiveness.     

Performance of a divided winding rotor machine with optimal controllers

A state-space model of a power system, where the long transmission line is represented by the constants A, B, C and D of its equivalent π-network (shunt compensating reactors are also taken into consideration), with a divided winding rotor (d-w-r) synchronous generator is obtained with an all-measurable state vector. The damping of the system with conventional excitation and prime mover controllers acting alone and with (a) optimal controllers and (b) optimal controllers with a prescribed degree of stability is assessed from the eigenvalue placement of the resultant closed-loop systems. Both controllers (a) and (b) referred to above, synthesized for full-load operating conditions, were tested under different load conditions to ascertain the feasibility of obtaining a fixed controller to cover a wide range of operating conditions.     

Enhancing optimal controllers via techniques from robust and adaptive control

Optimal control strategies for both non-linear and linear plants and indices are notoriously sensitive to modelling errors and external noise disturbances. In this paper a general framework to enhance robustness of an optimal control law is presented, with emphasis on the non-linear case. The framework allows a blending of off-line non-linear optimal control, on-line linear robust feedback control for regulation about the optimal trajectory and on-line adaptive techniques to enhance performance/robustness. The adaptive-Q techniques are those developed in previous work based on the Youla-Kucera parametrization for the class of all stabilizing two-degree-of-freedom controllers. Some general fundamental stability properties are developed which are new, at least for the non-linear plant and linear robust controller case. Also, performance enhancement results in the presence of unmodelled linear dynamics based on an averaging analysis are reviewed. A convergence analysis based on averaging theory appears possible in principle for any specific non-linear system but is beyond the scope of the present paper. Certain model reference adaptive control algorithms come out as special cases. A non-linear optimal control problem is studied to illustrate the efficacy of the techniques, and the possibility of further performance enhancement based on functional learning is noted.     

电解铝工业园区的源荷协同优化配置方法

随着风电和光伏并网容量的不断增加,其固有的波动性与间歇性特征加剧了火电机组调峰的难度。电解铝负荷具有耗电量大、调节速度快等特点,可作为负荷侧灵活性资源参与系统规划。分析了电解铝负荷的生产原理与供电方式,推导了电解铝负荷的功率与产量的关系,进而建立了电解铝负荷的多阶段需求响应模型。针对电解铝工业园区,以新能源场站的建设成本与工业园区电力系统的运行成本最小为目标,计及电解铝负荷的调节时间、调节深度等特性,建立了考虑电解铝负荷需求响应的源荷协同优化配置模型,促进电解铝负荷与火电机组、可再生能源的协调互补。在求解时,使用变量替换、大M法对模型中的非线性约束进行线性化,将原问题转化为混合整数二次规划问题,从而实现利用商业求解器快速求解。采用实际算例进行仿真计算,结果表明所提方法可以同时兼顾系统经济性与新能源利用率,实现电力系统经济优质运行的目标。     

一种优化协调控制策略在VSC HVDC 中应用

随着大功率电力电子技术的发展和可工作在高频率开关状态的完全可控器件(如大功率IGBT，IGCT等)的出现，使得电压源型直流输电(VSCHVDC)成为现实，这种新型的直流输电技术和传统直流输电相比，体现了诸多优点。该文建立了一种适合于研究VSCHVDC基频下的运行与控制特性的VSCHVDC模型，并将该模型方程与电力系统微分代数方程统一起来。在此基础上提出一种VSCHVDC与发电机励磁协调控制策略，在AC／DC交直流混合系统中研究了该控制方式对各自的影响，仿真表明，采用该优化协调控制，发电机和HVDC在系统发生故障或者扰动后都能够快速恢复正常稳定运行，且该控制方式对于系统参数变化具有一定鲁棒性。     

计及差异化需求响应的微电网源荷储协调优化调度

为应对微电网中源荷匹配性较差及弃风弃光的问题,计及需求响应对微电网源荷储协调优化调度进行研究。为了更准确地体现实际需求响应的特点,根据电量价格响应弹性的非线性特点和不同类型负荷响应弹性的差异性,提出基于指数变化的差异化需求响应机制;建立以系统运行成本最低为目标的微电网源荷储协调优化调度模型;通过引入多核并行运行环境和双策略微分进化变异机制构造并行双策略微分进化算法,该算法兼顾寻优深度和寻优速度,实现了对模型的高效求解。算例结果表明,所提方法能够有效改善源荷两侧的匹配度以实现削峰填谷,并能提升系统风光消纳量以及节约运行成本。     

一种优化协调控制策略在VSC HVDC中应用

随着大功率电力电子技术的发展和可工作在高频率开关状态的完全可控器件(如大功率IGBT,IGCT等)的出现,使得电压源型直流输电(VSC HVDC)成为现实,这种新型的直流输电技术和传统直流输电相比,体现了诸多优点.该文建立了一种适合于研究VSC HVDC基频下的运行与控制特性的VSC HVDC模型,并将该模型方程与电力系统微分代数方程统一起来.在此基础上提出一种VSC HVDC与发电机励磁协调控制策略,在AC/DC交直流混合系统中研究了该控制方式对各自的影响,仿真表明,采用该优化协调控制,发电机和HVDC在系统发生故障或者扰动后都能够快速恢复正常稳定运行,且该控制方式对于系统参数变化具有一定鲁棒性.     

基于混合博弈的多微电网双层协调优化调度

考虑多微电网系统(MMGS)和微电网聚合商(MA)所有权不同,以及各微电网(MG)间能量互济与利益分配,提出基于混合博弈的MMGS双层协调优化调度模型及其求解方法.上层MA与下层MMGS之间采用基于Stackelberg的主从博弈,保证MA与MMGS的利益双赢;MA作为领导者,以自身收益最大为目标,在证明Stackel...     

Simultaneously tuning decentralized nonlinear optimal excitation controllers in multimachine power systems

This paper proposes an approach to simultaneously designing multiple decentralized nonlinear optimal excitation controllers to achieve rotor angle stability improvement and good trade-off between voltage regulation and oscillation damping in multimachine power systems. The approach includes: (1) building a novel state-space mathematical model based on nonlinear feedback compensation, (2) properly formulating the control problem and (3) developing a more quick and accurate algorithm to solve the problem. Case studies are fulfilled in a two-area four-machine power system to verify the effectiveness of the approach. Digital simulation results show that the controllers designed with the proposed method gain much priority over traditional AVR/PSS in damping power oscillation, improving voltage regulation and enhancing transfer capability.     

Real-time optimal power flow in automatic generation control

The authors describe the concept, mathematical formulation, and solution of a real-time OPF (optimal power flow) in an energy management system. The real-time OPF replaces a classical real-time economic dispatch whenever a network flow violation occurs. To meet performance requirements (solution speed and frequency of execution) a two-stage approach is proposed. A full OPF is first executed in a nontime-critical mode and the critical branch flows are determined. Then, a constrained economic dispatch is executed based on the critical constraint set determined during the first stage. The execution frequency of the second stage is the same as the execution frequency of a standard real-time economic dispatch     

主动配电网多源协同三层优化调度

合理协同各类并网间歇性能源、储能装置、柔性负荷等可调资源,是实现主动配电网优化调度的有效途径。在设置各类能源调度顺序及分段开关控制方案的前提下,从环境、运行、经济三个层面,构建主动配电网多源协同三层优化调度模型,并运用一种融有蛙跳算法、遗传算法核心思想的改进人群搜索算法求解该模型。仿真结果表明多源协同优化调度可有效提升可再生能源消纳率、平稳负荷波动、降低网络损耗、提高用户体验,由此证明该优化方案的合理性及优越性。     

考虑机组灵活性的独立微网日前日内协调优化调度

作为高效利用分布式能源以及补充大电网灵活性的有效手段之一,微网的优化调度越来越受到重视。在全面考虑各类分布式资源调度灵活性的基础上,从日前和日内2个时间尺度出发,建立以总运行成本最小为目标的独立微网优化调度模型。日前调度计划为日内调度提供参考,必要时在日内调度中可调整满足灵活性要求的分布式资源的启停状态;日内调度采用滚动优化方式,并通过制定各类分布式资源的调整优先级,指导日内调度计划的优化调整。将蓄电池初始荷电状态作为优化变量,与分布式资源的调度计划同时进行优化,以进一步提高微网运营经济性。对该模型进行线性化处理,并调用CPLEX求解器求解该混合整数规划问题。算例分析结果验证了所提调度策略的合理性。     

多类型源储协调互动的配电网分布鲁棒优化调度

分布式光伏、风电等可再生能源出力具有较强的随机性和不确定性,其大量并网给配电网的运行带来了极大的挑战。本文提出了一种多类型源储协调互动的配电网分布鲁棒优化调度方法,基于分布鲁棒优化理论,对配电网中传统离散设备、可再生能源以及储能决策进行协调优化,提高配电网运行的经济性和安全性,实现了配电网运行决策保守性与鲁棒性的有效平衡。首先,考虑多类型源储资源的协调互动,建立配电网优化调度模型,并将其转化为混合整数二阶锥规划的形式;其次,利用可再生能源出力场景集进行不确定性刻画,建立分布鲁棒优化模型,并通过列和约束生成算法进行求解;最后,在PG&E69节点系统上进行算例分析,验证了所提方法的可行性与准确性。     

包含蓄电池储能的微网实时能量优化调度

提出一种包含蓄电池储能的微网实时能量优化调度方法。该方法将全天24 h划分为峰、平、谷3种时段,在实时调度时,根据当前调度时刻所处的不同时段和蓄电池荷电状态所处的不同范围,采用不同的运行调度策略,同时以各微电源的有功输出与无功输出作为优化变量建立能量优化模型,设计了蓄电池放电罚函数并计入能量优化模型的目标函数中,可确保蓄电池随时维持一定的储能量以便在非计划孤网突然发生时为微网提供紧急功率支撑。该方法不仅可实现微网的可靠、经济运行,还有助于对主网进行"削峰填谷"。算例分析验证了所提方法的有效性。