Optimal power flow by BAT search algorithm for generation reallocation with unified power flow controller

Optimal power flow with generation reallocation is a suitable method for better utilization of the existing system. In recent years, Flexible AC Transmission System (FACTS) devices, have led to the development of controllers that provide controllability and flexibility for power transmission. Out of the FACTS devices unified power flow controller (UPFC) is a versatile device, capable of controlling the power system parameters like voltage magnitude, phase angle and line impedance individually or simultaneously. The main aim of this paper is to minimize real power losses in a power system using BAT search algorithm without and with the presence of UPFC. Minimization of real power losses is done by considering the power generated by generator buses, voltage magnitudes at generator buses and reactive power injection from reactive power compensators. The proposed BAT algorithm based Optimal Power Flow (OPF) has been tested on a 5 bus test system and modified IEEE 30 bus system without and with UPFC. The results of the system with and without UPFC are compared in terms of active power losses in the transmission line using BAT algorithm. The obtained results are also compared with Genetic algorithm (GA).     

UPFC系统的变压器差动保护分析

并联变压器和串联变压器是统一潮流控制器(UPFC)的核心交流器件,差动保护作为这两类变压器的主保护,受UPFC特殊的运行工况影响,在不同的运行条件和不同类型的故障下会表现出不同的特性。为分析评估UPFC中各类故障对差动保护的影响,文中以实际UPFC工程的控制系统为基础,讨论了各类故障下可能对并联、串联变压器差动保护灵敏性及可靠性产生影响的因素;根据变压器区内外典型故障的仿真结果,分析了差动保护在此类故障下的行为特征,形成差动保护的适应性分析,验证了保护配置的有效性;从保护设备的角度出发,讨论了阀控制保护与交流继电保护的关系,从防误和防拒两方面为UPFC工程的交流继电保护实施提供技术参考。     

一种基于自适应遗传算法的统一潮流控制器

提出一种自适应遗传算法的智能控制策略,并将其应用于统一潮流控制器的多变量控制中.对3个通用的标准测试函数进行了优化,将其测试结果与简单遗传算法进行了比较.仿真结果表明:自适应机制提高了算法的搜索性能,与传统PI控制相比具有更强的动态性和鲁棒性。     

计及UPFC的主动配电网日前-实时优化策略

针对统一潮流控制器使优化策略模型非线性化,实时阶段计及模型时序耦合特性增加了智能算法求解维度,不利于优化的问题,提出了日前-实时优化策略。日前优化为不考虑统一潮流控制器的线性模型,确定实时优化的微型燃气轮机调节幅度上、下限,以保证模型收敛;针对统一潮流控制器使网损下降及新能源出力、负荷预测偏差,在实时阶段调整日前优化策略,通过消除时序耦合实现计及统一潮流控制器的单时段优化以降低求解维度。最后,通过算例分析验证了所提模型的有效性。     

基于PID神经网络的UPFC潮流控制方法研究

建立了UPFC的数学模型,将PID神经网络控制方法应用于UPFC的潮流控制,提出了PID神经网络控制器的设计方案,仿真结果表明,UPFC采用PID神经网络控制方法以后,响应时间更快,对有功功率和无功功率的变化具有很好的追踪能力,鲁棒性良好.     

统一潮流控制器的模糊控制策略设计

本文建立了UPFC的动态数学模型,提出了UPFC的模糊控制策略。并对UPFC的四个调节器分别设计了控制器。文中对UPFC的阻尼控制器进行了改进,给出了运用带多个因子的模糊规则自调整的模糊控制器。并运用MATLAB的仿真工具,对含UPFC的双机系统进行了仿真。仿真结果表明,UPFC采用模糊控制后不但能有效地调节线路潮流,而且能有效地抑制振荡,提高电力系统的暂态稳定性。     

使用灵敏度因子优化UPFC布点

在现代电力系统中,统一潮流控制器(UPFC)是调节电压和潮流的有效手段。在实际项目执行阶段UP FC的安装地点问题显得尤为重要。目前存在的布点方案没有考虑输电线路阻塞对布点结果的影响。该文引入线路有功潮流性能指数的概念,考虑了线路实际潮流与额定值的相对大小关系,采用有功过负荷的严重程度作为指标,根据UPFC参数对其产生影响的灵敏度因子大小来确定最佳安装地点。经算例验证,该方法简便快速,准确可行。     

Knowledge domain states mapping concept for controller tuning in an interconnected power network

This paper presents novel power system stabilizers (PSS) tuning approach with particles swarm optimization (PSO) driven knowledge domain states mapping for multi area power system. Tuning of PSS parameters has been done by PSO technique offline at different operating conditions as load dynamics change. The objective function for PSS parameters tuning is integral time multiplied by absolute error (ITAE). The sets of tuned parameters at different operating conditions thus obtained are termed as knowledge domain. The process is viewed as knowledge domain mapping. The dynamical system response has been linked with states, and if there is any violation from desired limits, control action is initiated and thus retuned control parameters obtained straight away from the respective knowledge domain helps to provide quick response and precise damping of signals of interest. Proposed concept also demonstrates that if one controller (PSS) fails to stabilize the system at certain operating condition then another controller (UPFC) connected in the system acts as supplementary controller in automation which assists PSS functioning and thus entire system operation improves by way of modulating the signal dynamics at interface points which quickly damps oscillations. The system study has been performed on a sample six area power systems comprising of UPFC connected between area two and three and PSS to all areas. The proposed concept demonstrates auto tuning of PSS for quick oscillation damping as the operating conditions change and also under situations of PSS failure due to relatively larger perturbation, UPFC acts as supplementary controller by assisting the entire system PSS to recover ensuring stability.     

电力潮流灵活控制技术应用综述

统一潮流控制器(unified power flow controller, UPFC)、静止同步串联补偿器(static synchronous series compensator, SSSC)、可控串联补偿装置(thyristor controlled series compensation, TCSC)和移相器(phase-shifting trans former, PST)能够调节线路参数、灵活控制潮流变化,均已在国内外电网中实现工程应用,对均衡输电通道潮流、提升供电能力有重要作用。文中对UPFC、SSSC、TCSC和PST的理论研究和工程实践进行了综述。首先,分析了4种潮流控制装置的基本结构和控制原理,并介绍了国内外已投运工程的运行情况;其次,从结构、换流器技术、选址定容、控制策略、故障保护5个方面对潮流控制装置的关键技术研究现状进行概述;最后,展望了潮流控制装置在未来电网中的典型应用场景,并对潮流控制技术的研究方向进行了分析。     

UPFC对风电场稳定性影响的仿真研究

在风速变化过大或发生短路故障时,异步风力机的电压变化也大,馈入电网的有功也有较大变化,与系统交换的无功增加,超过了系统安全约束,导致风电场停运。UPFC可以控制电压和潮流,维持风电场电压,减少无功交换,提高风电场有功的输送极限,维持系统稳定。通过Matlab/Simulink建立仿真模型,对UPFC的作用进行了验证。