Fuzzy dynamic programming approach to reactive power/voltagecontrol in a distribution substation

A fuzzy dynamic programming (FDP) approach is proposed for solving the reactive power/voltage control problem in a distribution substation. The main purpose is to improve the voltage profile on the secondary bus and restrain the reactive power flow into a main transformer at the same time. To reach our objectives, the load tap changer (LTC) usually installed in a main transformer is employed to adjust the secondary voltage and the capacitor connected to the secondary bus is employed to compensate the reactive power flow for the load demands. We first forecast the real and reactive power demands of a main transformer and its primary voltages for the next day. With these forecasting data at hand, a fast LTC tap position estimation formula that takes the load models into account is derived to effectively reduce the computational burden for the proposed approach. Practical constraints on bus voltage limits, maximum allowable number switching operations in a day for the LTC and capacitor and the tolerable worst power factor for a main transformer are also considered. To demonstrate the usefulness of the proposed approach, reactive power/voltage control at a distribution substation within the service area of Taipei City District Office of Taiwan Power Company is investigated. It is found that a proper dispatching schedule for the LTC and capacitor can be reached by the proposed approach     

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.     

智能型动态无功补偿在低电压治理中的实践

文中结合湖南省永州市冷水滩10 kV线路横油线的现状,选定适合现场实际的无功补偿组合方案,开发出智能型动态无功补偿装置并运用于工程实际。该工程的实施是新型无功补偿装置在农配网低电压综合治理方面的一次有益尝试。     

模糊控制理论在变电站电压无功控制系统中的应用

阐述了变电站电压无功补偿的重要性,指出了传统九区图的分区控制策略中存在的问题,提出了基于模糊控制理论和九区图相结合的电压无功控制策略.设计了电压模糊控制子系统和无功模糊控制子系统,并通过算例仿真试验,对比了采用模糊控制策略和九区图控制策略调整变压器二次侧电压的控制效果,其试验结果表明,模糊控制策略优于九区图控制策略,而...     

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.     

利用Simulink对变电站电压无功综合模糊控制的仿真

本文利用MATLAB的模糊逻辑工具箱对实例变电站的电压无功综合控制设计模糊控制系统。利用Simulink中的电力系统模（SimPowerSystems）对实例变电站进行搭建,并将设计好的模糊控制系统与构建的变电站模型连接,完成对变电站电压无功的模糊控制,并对此运行模型得出仿真结果。分析仿真结果,满足预先的设计思想及理论要求。     

220kV三绕组降压变电站电压无功控制策略研究

变电站电压无功控制系统可提高电压的质量和降低电网的有功损耗，目前的综控装置主要针对2个电压等级的变电站，其控制策略一般使用九区图原理，易产生变压器分接头调节频繁的缺陷，针对220kV三绕组降压变电站，提出一种电压无功综合控制的总体原则和具体控制策略，根据负荷变化规律，1d被分为谷，谷转峰，峰和峰转谷4种，在不同时优采用不同的控制策略，在每个时段以低压侧电压为主控制目标，同时兼顾无功平衡和中压侧电压合格，并尽力实现逆调压，通过预计算调节后电压无功的变化量，并以此作为调节条件的组成部分，防止了频繁调节，在控制策略中还引入高压侧电压过高和过低时的相应控制措施，有利于系统电压的稳定，通过对实际变电站的仿真计算，效果良好。     

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。     

变电站电压和无功功率调节分析

电压和无功功率控制的研究是电网规划和系统运行所面临的重要课题。通过对集中控制和分散控制这两种自动控制方式的具体分析,根据地区电网的实际运行需要,提出变压器和电容器分阶段参与调节、电压网损分级优化的思想,针对现有变电站电压无功控制九区图的特点和三线圈变压器与两线圈变压器的不同,提出了改进措施。     

电压调节和无功补偿技术在城市配电网中的降损作用

结合揭阳老市区10kV配电网络的实际,着重阐述电压调节和无功补偿在城市配电网改造中节能降损的重要作用,提出配电网调节和无功补偿的方法,并指出当前城网改造中应大力应用电压调节和无功补偿技术。     

电网实施电压无功综合控制

从满足用户电能质量需求点出发,结合地区电网电压无功综合控制的实施,从技术管理角度上分 析了面向全网电压无功综合控制的特点、经济性和实施效果;从而提出在实时监控系统的支持下,对所 控范围实施整个网络的电压无功综合控制是实现电网经济运行和低成本电力服务的有效措施。     

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.     

Improved voltage and reactive power distribution factors for outagestudies

This paper presents the development of a simple and fast method to calculate a new set of distribution factors using the sensitivity property of Newton-Raphson load flow Jacobian at a base operating point. These factors have been used to calculate the post-outage voltages and reactive power output of the sources following outage of a transmission branch or a generator. The accuracy of post-outage results using these distribution factors has been established with respect to full AC load flow results on IEEE 14-bus, IEEE 57-bus and a practical 75-bus Indian power systems     

Development of an advanced voltage control technique to improve voltage and reactive power characteristics of a large-scale power cable system

The power supply system for a metropolitan area consists of multiple 275-kV power cable systems to supply power to a large number of consumers. Each system has a large charging capacity (capacitive reactive power). When 275-kV power cable systems experience a voltage drop, their charging capacity decreases. However, the reactive power losses increase in the 275-kV overhead transmission lines, which supply large power to power cable systems, thus causing the performance of the power supply system to deteriorate. In this paper, the following three points are reported:

• 1 When the secondary power system of the trunk substation is a large-scale power cable system, new techniques can greatly improve the voltage and reactive power characteristics by controlling the rise of the sending-end voltage at the secondary side of the trunk substations and maintaining the voltage of power cable systems at a constant level.
• 2 In the use of this control technique, it has been demonstrated that controlling by the direct-detecting method of a voltage drop in the primary power system is superior to one that controls by the indirect-detecting method, which increases load power in the cable system.
• 3 The results of simulations obtained by using a 275-kV cable system model and a performance power system model show that the use of this control technique can produce a good effect despite the allowances made for the opposite effect, i.e., a decrease in the capacity of power capacitors resulting from voltage drop at the tertiary voltage of a 500-kV transformer.

This study is carried out to examine the possibility of lightning control using a photoionized plasma produced by a UV laser without an optical air breakdown. As the fundamental experiment, the characteristics of a laser-triggered spark gap (LTSG) are examined, where a laser beam is not irradiated on the surface of the electrodes. In this experiment, the KrF excimer laser is very effective in increasing the plasma density n_e and the reduction ratio p of 50 percent breakdown voltage against the self-breakdown voltage. The relation between n_e and p is increased by generating a long and high-density plasma parallel to the discharge axis. On the other hand, the abnormal discharge process in triggered lightning using a rocket is examined, and it is indicated that the most important condition to trigger a lightning discharge is the production of a plasma channel of length 200 m and density about 10¹⁹ m^?3. It is suggested that such a plasma channel could be produced by a KrF excimer laser with an energy of only about 3.67 J.     

基于负荷预报的区域电网电压无功控制

电网电压无功优化运行自动控制过程中，由于负荷的波动会造成各变电所电容的投切和有载主变分接头调节振荡或者不必要操作。为避免设备不必要的操作，延长设备的运行寿命，在电网电压无功优化运行自动控制的基础上，引入短期和超短期负荷预报技术，在每日开始的时记得预测当日的负荷曲线，划分出高峰、低谷、腰荷时间段，并对每一个状态断面后若干时间(如15min)的电网负荷状况进行超短期预报，实现电网电压无功优化运行与调节设备动作次数的最佳组合，提高系统电压稳定性，降低网损，减少设备动作次数。     

电压无功功率控制装置在变电站中的应用

变电站中安装电压无功功率综合控制(VQcC装置,无疑可以提高母线电压质量合格率并使无功功率就地平衡,但如何使VQC装置在使用中达到最佳效果,一方面VQC装置本身必须功能齐全,安全可靠,整定值科学合理;另一方面供给VQC装置的数据要准确,这就要求在工作中加强设备维护、运行管理,为此,探讨了东莞供电分公司使用VQC装置的一些经验,以供同行参考。     

全网无功优化的变电站电压无功控制策略

九区图是以工作点是否位于最优控制区为启动控制判据的无功优化调控策略;五区图是一种基于动作效果预算,以操作优劣距离为判据,面向VQC装置的调控策略;针对五区图的边界盲区缺乏明确的动作判据的缺陷,提出了九区图五区图组合调控策略;对于全网的变电站,根据设定的最优限值曲线,按照九区图判断各变电站的无功调压设备的工作点区域及启动区的上下限,仅对有越限的变电站按照五区图进行VQC装置的调控,既可减少控制变量的频繁操作,又可保证全网电压的质量和全网潮流的最优分布.     

配网低压无功补偿装置的运行

针对南通市郊地区配电网实施无功补偿的实际需要 ,通过近期进行的配电网低压无功补偿装置的安装与运行分析 ,为今后低压电网开展无功补偿 ,更好地运用先进的无功补偿技术 ,提供了借鉴经验与运行建议     

A study of voltage and reactive power control methods for high‐efficiency operation of distribution networks

Transformers with on‐load tap changer and step voltage regulators are most often used for regulating the distribution network voltage. Their use, however, creates certain problems, namely, the voltage control is in discrete steps and the response time is not satisfactory enough. In addition, the power factor (p.f.) compensation relies on capacitors installed by electricity users which creates additional problems manifesting themselves in unexpected overvoltages during light load and increase of power losses. To solve these problems, the authors have proposed a new voltage and p.f. control system for distribution networks based on sophisticated power electronics technology. This paper describes our study on the operating theory of inverter‐controlled regulators and thyristor‐controlled reactors, which play important roles in this system, and the results of simulation through which the usefulness of these equipment has been ascertained. © 1999 Scripta Technica, Electr Eng Jpn, 130(1): 76–87, 2000