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     

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。     

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     

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     

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     

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     

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.     

一种基于图形化编程的无功动态补偿装置的研制

通过对供电系统特点及无功补偿原理的分析,提出了一种无功动态补偿的设计方法,利用图形化编程技术的优势,开发了无功动态补偿装置.     

Linear reactive power optimization in a large power network usingthe decomposition approach

A mathematical framework is presented for the solution of the economic dispatch problem. The application of the Dantzig-Wolfe decomposition method for the solution of this problem is emphasized. The system's optimization problem is decomposed into several subproblems corresponding to specific areas in the power system. The upper bound technique along with the decomposition method are applied to a 16-bus system and a modified IEEE 30-bus system, and numerical results are presented for larger systems. The results indicate that the presented formulation of the reactive power optimization and the application of the decomposition procedure will facilitate the solution of the problem. The algorithm can be applied to a large-scale power network, where its solution represents a significant reduction in the number of iterations and the required computation time     

新型自动电压无功调节控制系统在220 kV变电站的实际运用

介绍了一种改进后面向220 kV变电站自动电压无功调节控制系统,该系统由于采用了双九区图控制与分时段优化、负荷优化,有效地提高了电压合格率,使得在电网的优化、可靠、经济运行等方面取得了满意结果.     

A source of reactive power at a 35-kV substation of the Vankor oilfield

An SRP-35/10/10 source of reactive power based on a magnetically controlled RTMU-10000/35-UHL1-series shunt reactor and a capacitor bank rated at 10 MV A at voltage 35 kV is described in this work. It was put into operation on October 28, 2011, at a 110/35/10 kV-substation at the NPS-1 site of CJSC Vankorneft??s Vankor oilfield after successful factory and site acceptance tests.     

含分布式发电的配电网有功—无功综合优化

为克服配电网中风力发电机和光伏电池出力随机波动、负荷变化带来的电压变动,研究了多种分布式电源接入配网后的电压控制问题。以分布式电源出力随机波动和负荷变化时每个时段的电压偏差和网损最小,以及尽量减少大电网向配电网输送有功为目标函数建立电压控制模型,采用粒子群优化算法对微型燃气轮机和燃料电池等出力稳定的分布式电源进行有功和无功综合优化,在保证电压质量的情况下减少对环境的污染。通过对IEEE33节点系统和一个实际算例系统分别进行仿真计算,结果表明该控制方案能在有效提高配电网电压水平的基础上提高环境效益。     

中压配电网计及动态无功补偿装置的理论线损计算

结合无功补偿电容器在配电网中的实际应用情况以及配电网的一些自有特点,充分考虑动态无功补偿电容器的投切状态,提出计及动态无功补偿装置的新的理论线损计算方法.该方法根据电容器"投切"动作的时刻将理论线损计算划分为更多的时段,提出新的实时数据处理方式,并且考虑到各个配电变压器日负荷曲线的差异,不仅可以获得比旧有方法精确许多的线损计算结果,而且可以获得在计算时间内的各个细分的小时段内的详细线损情况,明确地表现出加装无功补偿装置对于配网理论线损的影响,有利于运行人员进行配网线损分析与计算.     

Joint bus voltage/reactive generation control in multimachine power plants: a multivariable approach

This paper presents a design procedure for a centralized regulator, armed for the joint bus voltage/reactive generation control in multimachine power plants, by using the modern multivariable systems and optimal regulator theories. The regulator is of output feedback, proportional-plus-integral type. It is based on the concept of optimal linear regulators, using a reduced number of local measurements, and acting through reference inputs of individual unit's automatic voltage regulators. The proposed control is of two-level type, with separate features that enable the common plant-bus voltage control and desired distribution of reactive generation to individual units in operation.

The paper presents the procedure for the regulator system design and gives the simulation results performed on a 17th order, two-unit hydropower plant model and considers the practical feasibility of the regulator system.     

浅谈农村配电网的无功补偿

针对农村配电网的具体状况,说明对农村配电网进行低压无功补偿的必要性及其重要意义,并提出了农村配电网无功补偿的最佳方法.最后,对农村配电网无功补偿实例进行分析,比较补偿前后的功率因数、线路输送的无功功率、线路电压损失、年线损电量.比较结果表明：对农村配电网进行无功补偿的节能降损效果非常好.     

A mathematical programming approach to service restoration for distribution systems

This paper aims to develop a suitable power system restoration method by using mathematical programming (MP). Generally, the problem of determining the target configuration can be formulated as a mixed integer programming (MIP) problem. Whether or not each branch is included in a target system is expressed as a 0–1 variable, while the other constraints such as the demand and supply balance conditions are formulated in terms of continuous variables. Although an MP‐based method can obtain an optimal solution under specified operational constraints, in the case of large‐scale problems the solution time often exceeds the computation time that is practically available due to combinatorial explosion. The object of this paper is to develop an efficient solution algorithm for service restoration in distribution systems. First, an MIP problem is solved to determine the sound network configuration that maximizes the available power to the out‐of‐service area, then an MIP problem is solved to determine the target configuration for the out‐of‐service network. The proposed method has been applied to distribution system restoration problems, and simulation results demonstrate its effectiveness. © 2001 Scripta Technica, Electr Eng Jpn, 135(4): 35–42, 2001