A combined artificial neural network-fuzzy dynamic programmingapproach to reactive power/voltage control in a distribution substation

Reactive power/voltage control in a distribution substation is investigated in this work. The purpose is to determine proper capacitor on/off status and suitable load tap changer (LTC) positions for the 24 hours in the next day. To reach this goal, an artificial neural network (ANN) is designed to reach a preliminary dispatch schedule for the capacitor and LTC. The inputs to the ANN are main transformer real power and reactive power and primary and secondary bus voltages and the outputs are the desired capacitor on/off status and LTC tap positions. The preliminary dispatch schedule is further refined by fuzzy dynamic programming in order to reach the final schedule. To demonstrate the effectiveness of the proposed method, reactive power/voltage control is performed on a distribution substation in Taipei, Taiwan. Results from the example show that a proper dispatch schedule for capacitor and LTC can be reached by the proposed method in a very short period     

A hybrid tool to assist the operator in reactive power/voltagecontrol and optimization

This paper presents an integral tool to assist the operator in reactive power dispatching for voltage profile improvement and power loss minimization. Advantage is taken of both numerical (conventional) and heuristic (knowledge-based) methods in order to find a practical number of control variables (smooth and/or discrete) which can be effectively used to solve voltage violations or to reduce power losses. Efficiency is measured according to sensitivity of voltages (or power losses) to control variables, current voltage profile and reserve margins. Implementation details of the system, integrated in a control center, as well as some practical results are also presented and discussed     

牵引变电站动态无功补偿控制数学模型

为了减少电力牵引负荷对电能质量的影响,以Y/△-11接线的牵引变压器为例,分析了由电力牵引负荷引起的负序电流和电压损失,提出了以无功功率和母线电压为约束条件、以负序电流为目标函数的牵引变电站动态无功补偿控制的数学模型。根据电力牵引负荷的变化,计算出两供电臂所需的补偿容量,可在提高功率因数的同时,有效地减少牵引变压器高压侧的负序电流和低压侧的电压损失。     

Quadratic programming approach to reactive power optimization on the primary feeders

Contents In this paper we suggest the use of the quadratic programming technique to determine the optimum size and location of shunt capacitors on radial distribution feeders so as to maximize overall savings, including the cost of capacitors. The saving function which is of quadratic form is maximized for a set of linear inequality constraints by using quadratic programming. — For quadratic programming, efficient alogrithms have been developed which can easily be implemented on digital computers. — The approach is illustrated by an application to a typical distribution feeder of 23 kV.

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Blindleistungsoptimierung an primären Einspeisungen mit Hilfe quadratischer Programmierung

Übersicht Diese Arbeit stellt die Anwendung der quadratischen Programmierung zur Ermittlung optimaler Werte und Orte von Parallelkapazitäten an radialen Verteilungen mit dem Ziel der Kosteneinsparung vor. Die Methode ist an einer 23-kV-Verteilung entwickelt und überprüft worden.

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Nomenclature A M×N array of constraint coefficients - B M vector of constrain limits - C N×M array of quadratic coefficients, from objective function - E Energy loss caused by reactive current in the feeder - E Reduction in energy loss - I _ck Capacitor current injected at nodek - Î _k Maximum reactive load current at nodek - K _c Annual cost per unit of installed capacitor ($/A) - K _E Per unit energy production cost ($/kWh) - K _P Annual cost per unit of power loss ($/kW) - m _k Reactive load factor for loadk - M Number of constraints - N Number of structural variables - P N vector of linear term coefficients from objective function - P Peak power loss caused by reactive current in the feeder - P Reduction in peak power loss - R _k Line resistance for sectionk - S Net saving resulting from peak power and energy loss reduction - T Total period of the reactive load curve - X _k Line reactance for sectionk     

SVG复合型动态无功装置在变电站的应用研究

探讨了如何将变电站SVG与电网电压自动控制系统（AVC）进行通信连接,然后经变电站控制系统向AVC发送SVG容量等状态信息,SVG接受AVC下达的控制指令,校核后执行,实现变电站SVG的复合控制技术。     

牵引变电所无功动态并联综合补偿装置设计与实践

以迎水桥牵引变电所补偿电容的改造为例,提出了一种牵引变电所无功动态并联综合补偿装置,讨论了装置的基本构成,介绍了装置的调试、运行情况,以及滤波器组、吸流电抗器组的过零投切波形以及补偿效果.现场运行表明,本装置设计合理、补偿效果良好.     

牵引变电所无功动态并联综合补偿装置设计与实践

以迎水桥牵引变电所补偿电容的改造为例,提出了一种牵引变电所无功动态并联综合补偿装置,讨论了装置的基本构成,介绍了装置的调试、运行情况,以及滤波器组、吸流电抗器组的过零投切波形以及补偿效果。现场运行表明,本装置设计合理、补偿效果良好。     

考虑分布式电源无功调节的配电网两级动态无功调度策略

针对传统配电网两级动态无功调度策略存在的均衡度低、耗时长的问题,提出了考虑分布式电源无功调节的配电网两级动态无功调度策略。根据分布式电源的无功调节原理,设计了配电网安全态势功能模型,在引入数据处理技术的基础上,评估了配电网的网络安全态势。利用配电网两级的输出信道带宽,构建了影响配电网两级电力负载的期望方程。基于配电网节点耗能因子矩阵,得到了配电网两级动态无功调度的负载输出项,完成配电网两级动态无功调度的统计分析。通过制定配电网两级动态无功调度策略,实现了配电网两级的动态无功调度。实验结果表明,考虑分布式电源无功调节的配电网两级动态无功调度策略的均衡系数大于0.7,调度耗时在5 s以下,不仅具有更高的均衡度,还可以确保配电网两级动态无功调度具有更高的效率。     

变电所无功调节方法分析

电力系统通过多种调节无功功率的方法来保持系统内无功功率的平衡,从而保持系统内电压的质量。着重对电容器钟控、电容器自动投切装置、VQC电压无功组合控制系统等三种变电所无功调节的方案进行分析,并阐述这三种无功调节方案适用的范围。     

A particle swarm optimization for reactive power and voltagecontrol considering voltage security assessment

This paper presents a particle swarm optimization (PSO) for reactive power and voltage control (volt/VAr control: VVC) considering voltage security assessment (VSA). VVC can be formulated as a mixed-integer nonlinear optimization problem (MINLP). The proposed method expands the original PSO to handle a MINLP and determines an online VVC strategy with continuous and discrete control variables such as automatic voltage regulator (AVR) operating values of generators, tap positions of on-load tap changer (OLTC) of transformers, and the number of reactive power compensation equipment. The method considers voltage security using a continuation power flow and a contingency analysis technique. The feasibility of the proposed method is demonstrated and compared with reactive tabu search (RTS) and the enumeration method on practical power system models with promising results     

自适应动态预测变电站电压无功模糊控制系统的研究

介绍了一种基于自适应灰色系统理论及模糊控制理论的变电站电压无功综合控制系统和软硬件的实现方法。本系统对一定时间后的电压、无功做出预测并进行实时控制。对参数越限进行提前判断和决策,减少了电压、无功的不合格时间。将传统静态区间控制改进为动态分析控制,更好地反应系统的动态特性。应用模糊控制,提高了系统的调节能力和电压质量,保证了系统的稳定性。     

自适应动态预测变电站电压无功模糊控制系统的研究

介绍了一种基于自适应灰色系统理论及模糊控制理论的变电站电压无功综合控制系统和软硬件的实现方法.本系统对一定时间后的电压、无功做出预测并进行实时控制.对参数越限进行提前判断和决策,减少了电压、无功的不合格时间.将传统静态区间控制改进为动态分析控制,更好地反应系统的动态特性.应用模糊控制,提高了系统的调节能力和电压质量,保证了系统的稳定性.     

Application of evolutionary programming to reactive powerplanning-comparison with nonlinear programming approach

This paper proposes an application of evolutionary programming (EP) to reactive power planning (RPP). Several techniques have been developed to make EP practicable to solve a real power system problem and other practical problems. The proposed approach has been used in the IEEE 30-bus system and a practical power system. For illustration purposes, only results for the IEEE 30-bus system are given. Simulation results, compared with those obtained by using a conventional gradient-based optimization method, Broyden's method, are presented to show that the present method is better for power system planning. In the case of optimization of noncontinuous and nonsmooth functions, EP is much better than nonlinear programming. The comprehensive simulation results show a great potential for applications of EP in power system economical and secure operation, planning and reliability assessment     

大型并网风电场和光伏电站内动态无功补偿的应用技术分析

为了研究并网风电场和光伏电站内应用全容量SVG(Static Var Generator)动态无功补偿的必要性和特别要求,重点从调节特性与响应速度等性能指标对比研究了SVC(Static Var Compensator)和SVG两种型式的动态无功补偿装置。针对甘肃已并网多个新能源项目,分析了大型风电场升压站在无功配置方案和无功补偿设备运行方面存在的误区和一些细节问题,并结合典型事故进一步分析了电网故障情况下SVG对系统无功和电压的支撑作用。同时,研究了集中并网光伏电站内SVG的选型和典型电气接线方案以及SVG在实际工程应用中的常见故障问题,对类似工程具有指导意义。     

Practical reactive power allocation/operation planning usingsuccessive linear programming

A method for reactive power planning is presented that it finds an optimal solution for both allocation and operation planning in large systems using linear programming (LP). The method utilizes calculated linear sensitivities including active power and voltage phase angle in the formulation. Although the overall method includes these relations, the number of constraints and variables are not augmented in its first procedure, APPROACH-1. Its second procedure, APPROACH-2, overcomes numerical problems caused by a dense constraint matrix. This is achieved by retaining untouched sparse sensitivities in the constraint matrix and by eliminating any calculations related to the inverse matrix. The results of applying this method to a practical 224-bus system and the IEEE-30 bus system verify its robustness and fast convergence     

Fuzzy reactive power optimization in hybrid power systems

Reactive power control, which is one of the important issues of power system studies, has encountered some intrinsic changes because of the presence of the hybrid AC/DC systems. The uncertainty in determination of some ill-defined variables and constraints underlines the application of fuzzy set as an uncertainty analysis tool. Herein a fuzzy objective function and some fuzzy constraints have been modeled for the purpose of reactive power optimization then this fuzzy model is dealt with as a linear programming problem to be solved. Contrary to the separate modeling of the conventional AC/DC optimization methods, this study attempts to attain the most optimal solution by the simultaneous employment of the total contributing factors of both AC and DC parts. In this way, the conventional issue of the coordinated control of firing angle and the transformer tap of the DC terminals is resolved, yet the method provides more flexibility to gain the most optimal condition since it uses more control factor for solving the optimization problem. The proposed method is performed on the modified IEEE 14 and 30-bus systems; and it is shown to have less computational burden and further minimized objective function than the conventional method.     

配电网变电站经济供电半径研究

为减少规划投资并提高供电质量,针对变电站经济供电半径进行了研究。首先,构建了考虑变电站建设投资和运维费用并以单位供电面积年费用最小为目标函数的变电站供电半径优化模型,研究了变电站经济供电半径求解算法。其次,建立了不同负荷情形下的变电站供电半径和线路电压损失之间的定量关系,在此基础上根据配电网对电压损失的规定对优化计算得到的经济供电半径进行电压质量校验。通过对实际电网数据的测算,验证了算法的准确性和合理性。计算结果可为地区配电网规划提供有效的参考。     

含固态变压器新型配电网动态无功多目标优化

风机和光伏电池等分布式电源(distributed generator, DG)大量接入配电网会导致电压波动和网损增大等问题,需要对动态无功进行优化。但是由于风光存在的不确定性会影响动态无功优化的效果,因此提出了一种含固态变压器新型配电网动态无功多目标优化方法。首先,通过 Weibull 分布和 Beta 分布对风速和光照强度进行曲线拟合,再采用风机和光伏电池出力公式生成 DG 出力模型。其次,通过蒙特卡洛仿真抽样法对上述模型进行抽样,生成上千个DG日出力场景,并采用k-means 聚类算法将上千个场景聚类成k个典型场景,以缩短随机潮流计算时间。再次,以IEEE33 节点系统为基础,建立含固态变压器有源配电网方案和含有载调压变压器有源配电网方案,以日内网损和电压波动最小为目标,采用改进型多目标灰狼算法对两种方案的相关参数进行优化。最后,以优化后的相关参数进行仿真和对比,证明了所提方法在降低配电网网损和维持节点电压稳定方面的优越性。     

基于改进型动态规划算法的厂级负荷优化分配

在详细介绍了实行厂级负荷优化分配的重要性后,着重论述了用于火电厂厂级负荷优化分配的一般动态规划算法并指出其不足,提出了一种改进的动态规划算法,它根据经验所形成的策略来变换步长,再对不同步长下的所求解进行二次寻优,基本上克服了因步长选取不当而带来的非最优化问题.案例表明：改进型动态规划算法效果良好,具有不错的工程应用价值.     

电力系统无功优化模糊建模研究

传统无功优化算法的目标函数一般为满足电压限制下的有功网损最小,未考虑电压的"软约束"特性,这通常会使得优化后的系统部分母线电压非常接近其合格范围的边界,成为系统安全运行的隐患.针对无功优化问题的这些特点,引入模糊规划算法以解决这一问题.建立了带有模糊安全约束的无功优化模型,并采用非线性原-对偶内点法内嵌二次罚函数法求解.算例的结果表明,带有模糊安全约束的无功优化模型能够在降低系统网损的同时确保节点电压留有一定的安全裕度.