三单相结构的晶闸管电压调节器的研究

为了提高电网电压合格率,解决电网偏差问题,提出了一种基于晶闸管开关控制技术的电压调节装置——晶闸管电压调节器(TVR),介绍了TVR的工作原理、运行模式和整个电路的控制方法并通过Matlab仿真软件建立了仿真模型,进行了TVR补偿方案实验。仿真结果表明,TVR可以有效地调节电网电压保持在额定值范围以内,是解决电能质量问题的有效手段之一。     

Maximum capacity of distributed generators connected to a distribution system with a step voltage regulator,as determined with an electric power density model

In a distribution system containing a step voltage regulator (SVR), the maximum capacity of distributed generators (DGs) is calculated for DGs completely dispersed on a distribution line. The maximum capacity of the DGs is calculated under the constraint of an upper or lower voltage regulation value and an allowable current value by using voltage and current profiles expressed analytically in terms of our proposed power density model. As the voltage control method for the SVRs, we consider the conventional SVR, whose transformation ratio is fixed to 1 if it detects reverse power flow, and a reverse power flow SVR which operates appropriately even if it detects reverse power flow. Calculation of the maximum capacity of DGs with respect to the power factor of the DGs indicates which parameters, including the power factor of the DGs, the distribution of the DGs, and the load, influence the maximum DG capacity. Calculation of the maximum capacity of DGs versus the system length indicates that the constraints can be subdivided into two modes in the conventional SVR and four modes in the reverse power flow SVR. The maximum DG capacity in the system with a reverse power flow SVR is larger than that in a system with the conventional SVR. © 2008 Wiley Periodicals, Inc. Electr Eng Jpn, 165(4): 41–51, 2008; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20591     

Comparing secondary voltage regulation and shunt compensation for improving voltage stability and transfer capability in the Italian power system

This paper concentrates on comparing the advantages and disadvantages, including costs, of using secondary voltage regulation (SVR) versus using shunt-connected controllers, in particular mechanical switched capacitors (MSC), static var compensators (SVC) and static synchronous compensators (STATCOM), to improve voltage stability (VS) and the external transfer capability (TC) of the Italian power network. Basic VS and TC concepts and tools, as well as the models of the various controllers, particularly SVR, used to obtain the results presented are described in detail. The model of the Italian system used and the assumptions made for these studies are also discussed. The paper demonstrates that SVR is an option that should be seriously considered in practice when trying to improve VS and TC of power systems.     

含分布式电源的配电网电压无功优化问题研究

本文根据分布式电源对配电网的有功损耗和电压稳定与分布等方面的影响,针对含分布式电源的配电网,构建以节点电压合格率最高为目标的电压无功优化模型,然后结合配电网负荷变化及太阳能容量的变化特点,选取一天中3个典型的负荷点,采用多种电压无功调节装置(OLTC、SVR、SC和SVC)组合优化的策略对配电网电压进行优化控制,并采用收敛性较好的遗传算法求解最优电压,最后通过算例仿真分析几种电压无功调节装置不同组合情况下的电压优化效果,验证了几种组合方法均能对配网电压起到优化作用的正确性。     

Optimal tracking secondary voltage control for the DFIG wind turbines and compensator devices

The optimal tracking secondary voltage control (OTSVC) is a new developed voltage control scheme for wind park based Doubly Fed Induction Generator (DFIG). The proposed controller is developed to achieve efficient voltage regulation and provided optimal reactive power compensation to the interconnected power system. The performance of the controller for enhancing the network voltage profile is compared with secondary voltage control, primary voltage control and optimal voltage profile obtained from the optimal power flow analysis. Furthermore, the OTSVC is employed for controlling wind park based DFIG and other sources of reactive power such as static var compensator (svc). The dynamic performance of the controller for multiple sources of reactive power is tested for steady state operation and in response of system contingencies with considering the impact of communication time delays. Simulation results are presented and the capability of the controller in providing the desired reactive power compensation and voltage support for the power system are verified.     

A new modeling and placement of shunt FACTS devices in the secondary voltage regulation environment

Recently, the Secondary Voltage Regulation (SVR) is installed in some power systems in order to ensure the coordination voltage control devices. In other hand, the shunt FACTS devices such as the Static Var Compensator (SVC) and the STATic COMpensator (STATCOM) are extensively used for the local voltage control without any coordination with other voltage control devices, without any reciprocal coordination. In this paper, new models of SVC and STATCOM are proposed to be adopted in power flow models that include the SVR. The proposed models are implemented and tested on a model of the Italian power system. Furthermore, a new method based on sensitivity analysis is proposed to find the most sensitive placements for the installation of SVC and STATCOM. The results obtained show the highly computational performance of the propose models and also the effectiveness of the sensitivity analysis to find the best placements of SVC and STATCOM taking into account the SVR.     

Influence of distribution voltage control methods on maximum capacity of distributed generators

Recently, the number of distributed generators (DGs) connected to distribution systems has been increasing. It is important to know how large a generator output is permitted when the generators are connected to a distribution system with regulation of the line voltage, the line current, and the power factor of the generator connection point. The authors demonstrate differences of maximum output of the DGs caused by various voltage control systems in a short‐length system and a long‐length system by load flow calculation. The voltage regulation systems include the following six types: no control equipment, SVC (Static Var Compensator), existing SVR (Step Voltage Regulator), reverse flow type SVR which operates even in reverse flow, existing SVR and SVC, and reverse flow type SVR and SVC. A synchronous generator is considered as a DG in this paper. The calculation results show that the DG's maximum output is about 3300 kW in a short‐length system and about 540 kW in a long‐length system. However, the DG's maximum output increases to about 3750 kW on installing a SVC, and the SVC's capacity decreases on replacing an existing SVR with a reverse power flow type SVR in the long‐length system. © 2004 Wiley Periodicals, Inc. Electr Eng Jpn, 150(1): 8–17, 2005; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20050     

吉安地调AVC系统的安全控制策略及其实现

介绍了吉安地调自动电压控制（Automatic Voltage Control,AVC）系统的结构组成,对AVC系统基于安全可靠性原则进行的自动控制安全性设计作了详尽的说明,并对其在吉安地调的实现形式进行了介绍。该系统充分利用SCADMEMS平台提供的丰富信息,考虑足够有效的安全措施,对吉安地区电网电压无功进行综合分析及实时自动控制,显著减轻了运行人员的劳动强度,有效提高了吉安地区电网电压的合格率。     

A study on cooperative tap control method for voltage profile maintenance in distribution networks with distributed generators

The introduction of distributed generators (DGs) that can utilize renewable energy is of prime importance to solve the energy and environmental issues. When a distribution network has a large number of DGs, voltage maintenance becomes a serious problem. To solve this problem, we had proposed the ‘voltage profile control method’ using reactive power control of DGs. However, the control is limited to continuous reactive power control so far, and tap control has not been considered. It is important that the conventional voltage control equipment such as the load ratio tap changer (LRT) or step voltage regulator (SVR) is utilized in order to enhance the control efficiency of the voltage profile control method. Therefore, in this paper, we develop a new method that can realize a cooperative work between inverters and tap control of LRT and SVR. The proposed method is tested in 8‐ and 24‐node model systems and its effectiveness is shown. © 2012 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

晶闸管电压调节器控制器设计

为解决长线路和带有分散发电设备配电网的电压调节问题,开发、研制了一种用于中低压配电网、能双向调节电网电压的晶闸管电压调节器TVR(Thyristor Voltage Regulator)。重点介绍TVR控制器的设计思想和方法,包括控制器的总体设计、软硬件设计和抗干扰措施等;同时给出了控制器在380V电压调节器样机上的试验结果。试验结果表明：设计的TVR控制器能很好地实现调压操作、故障保护、定值设置、显示等功能。     

A GA approach to compare ORPF objective functions including Secondary Voltage Regulation

In the past, with vertically integrate utilities, Optimal Reactive Power Flow (ORPF) procedures were designed to minimize power system losses, keeping the voltage profile in an acceptable range. Nowadays, in the market environment, a new formulation of the ORPF, aimed at the system security maximization, is necessary. In particular, as congestions and overloads are usually taken into account by the energy market rules, voltage security could become the main goal of ORPFs. Voltage problems are caused by the increase in power transfer among areas of interconnected systems, by the lack of reactive power support and by the increasing limitations of transmission networks. In this paper, an analysis of several ORPF Objective Functions (OFs) is reported, where the goal considered is the network security maximization. To solve the optimization problem for the considered OFs, a Genetic Algorithm (GA) approach has been adopted, together with a particular formulation of the Power Flow (PF) taking into account the Secondary Voltage Regulation (SVR). Tests are performed on a detailed model of the Italian power system, comparing the results in terms of system losses, reactive power required, loadability limits and voltage collapse indices. Furthermore, the improvements achievable with the adoption of the SVR in the new market environment have been investigated.     

A multivariable new control solution for increased long lines voltage restoration stability during black startup

This paper deals with the stability problems which can determine failures of long lines voltage restoration maneuvers during black startup. Also of concern, a new control solution is shown, capable of facing the phenomena of voltage instability and self-excitation, which frequently occur in the alternator-line system. The paper presents a theoretical analysis, which reconstructs and justifies the described dynamic phenomena. It is mainly concerned with the influence of alternator and grid electrical parameters on the transient characteristics of the voltage restoration maneuver. It also describes the most significant results of a dynamic study, based on a simulation model of a generalized plant-grid system, suited to the purpose of the investigation. Specific corrective actions, to be essentially taken on the excitation control system, are furthermore outlined. In this context, the most effective solution is a multivariable control scheme, involving use of new underexcitation limits or, better yet, a superimposed centralized reactive power control. The objective is to reduce line energization extra-voltages, balancing the control efforts of all power plant units while stabilizing underexcitation operation of the generators, and preventing self-excitation wherever possible. Such a control feature could easily be implemented, in the Italian network, using the reactive power regulator (REPORT), currently widely employed for secondary voltage regulation (SVR) applications.     

Study on a Voltage Estimation of Tap‐Changing Transformer in Consideration of SVC Introduction

Recent years, installation of photovoltaic (PV) system is active by the environmental problem and feed in tariff system. Due to PV's output fluctuation, the static var compensator (SVC) made by power electronics technology is planning to install in distribution system. The SVC is expected for maintain the voltage. But SVC differs in a theory of operation of the existing voltage controller load ratio control transformer (LRT) and step voltage regulator (SVR). Because the SVC operation makes the system impedance changes, the existing voltage controller may not operate effectively. In this study, the intelligent‐control method which used the radial basis function (RBF) network is proposed. This method can reduce the effects of the SVC operation by including the performance characteristics of SVC in the conventional method. An advantage of unnecessary arrangement attention of the SVC setup node and easy cooperation with the existing equipment is obtained by applying this method.     

智能配电网无功电压控制系统研究及应用

分析了智能配电网无功电压控制系统的应用要求,提出了实施智能配电网无功电压控制系统的实现方案,并通过详细的无功优化计算和现场测试分析给出了智能配电网无功电压控制系统中各类治理设备具体配置要求,总结了系统示范应用的成效,易于开展智能配电网无功电压控制系统的推广。     

新型电压调整与无功补偿设备在农村配电网中的应用

针对农村配电网存在的因线路过长导致电压和功率因数不合格、线路损耗大的问题,提出在配电线路中采用新型电压调整与无功补偿设备,以有效地提高配电网功率因数,减少线路电能损耗,改善电压质量,提高供电能力。从工程实际出发,介绍了SVR系列馈线自动调压器和DWK型户外高压无功自动补偿装置的工作原理及其在贵州电网农村配电网的应用情况。     

大电网省地协调自动电压控制（AVC）的研究

在分析电压协调控制难点的基础上,结合省级电网的实际情况,提出了省地协调电压控制的总体技术方案。详细阐述了协调控制量的确定、控制策略及执行控制策略的方式,该设计方案成功应用于江西电网省地协调AVC控制。     

基于p-q-r理论的UPQC直接控制策略

阐述了p-q-r瞬时功率理论的原理,提出了基于该理论的统一电能质量控制器(UPQC)的直接控制策略,探讨了将其用于三相四线非线性及不平衡系统中的实现方法。着重介绍了p-q-r参考波形的产生方法,以及串联补偿电流和并联补偿电压的计算方法,并将其应用于非线性不平衡负载在电源电压不平衡及电压跌落情况下UPQC直接控制策略中。分析了控制策略的原理,推导出相关运算公式,给出了详细的控制框图。Matlab/Simulink仿真结果表明,采用该方法可以有效地消除非线性及不平衡负载对电网的影响,使电网输入功率因数为1,同时,串联补偿器隔离了电网电压对负载电压的扰动,并联补偿器给负载提供三相平衡及正弦的额定电压,不受电网电压变化的影响。     

基于CNN-GRU的光伏电站电压轨迹预测

光伏电站出力随机性易引发并网点电压大幅度波动,通过趋势预测提前调控是提高电压稳定性的有效途径。为了提升电压趋势预测精度,提出一种基于卷积神经网络（convolutional neural networks,CNN）和门控循环单元（gated recurrent unit,GRU）的电压轨迹预测方法。首先,通过采集单元提取电压数据构建时间序列;然后,计算电压时间序列的自相关系数及其与外部变量间的最大信息系数（maximal information coefficient,MIC）,分析电压时间序列与外部变量在时序上的关联性;再通过CNN网络提取输入数据的高层特征;最后输入至GRU网络完成电压轨迹预测。通过某地光伏电站实测数据进行验证,结果表明：本文模型与GRU、长短期记忆网络（long short-term memory,LSTM）、CNN-LSTM、支持向量回归（support vector regression,SVR）等模型相比预测准确度更高。     

基于CNN-GRU的光伏电站电压轨迹预测

光伏电站出力随机性易引发并网点电压大幅度波动,通过趋势预测提前调控是提高电压稳定性的有效途径。为了提升电压趋势预测精度,提出一种基于卷积神经网络（convolutional neural networks,CNN）和门控循环单元（gated recurrent unit,GRU）的电压轨迹预测方法。首先,通过采集单元提取电压数据构建时间序列;然后,计算电压时间序列的自相关系数及其与外部变量间的最大信息系数（maximal information coefficient,MIC）,分析电压时间序列与外部变量在时序上的关联性;再通过CNN网络提取输入数据的高层特征;最后输入至GRU网络完成电压轨迹预测。通过某地光伏电站实测数据进行验证,结果表明：本文模型与GRU、长短期记忆网络（long short-term memory,LSTM）、CNN-LSTM、支持向量回归（support vector regression,SVR）等模型相比预测准确度更高。     

Positive Effect of Constant Leading Power Factor Operation of PV in Power System

A voltage rise problem in distribution networks has been discussed as the foremost concern with respect to the spread of large numbers of photovoltaic systems. We focus on the latent ability of the present distribution network and photovoltaic systems to find a low‐cost solution to the problem and consider a solution to mitigate the voltage rise using the photovoltaic system's constant leading power factor operation. Previously, based on simulations using an aggregated model of a real distribution network, we proposed that a combination of a photovoltaic system's constant leading power factor operation and LDC makes it possible to maintain the line voltage and LTC tap position adequately. In this paper, additionally, we confirm some effects of the proposed method in an aggregated model of a distribution network and a trunk power system. One of them is that the proposed method reduces the frequency of restricting output power from photovoltaic systems and changing the LTC and SVR tap position, although photovoltaic systems rapidly fluctuate. Another is that the proposed method cannot make a significant impact on a trunk power system in a voltage class exceeding 6.6 kV.