考虑电压约束的配网分布式电源准入功率研究

为了解决分布式电源接入配网的电压越限问题,首先分析了分布式电源接入对配网电压分布的影响,然后分析了对系统功率损耗的影响。利用得出的结论提出一个基于最优潮流的配网管理系统,该系统使用主动控制策略,能够在改善线路电压分布、降低系统功率损耗的基础上提高分布式电源的准入功率。     

基于分布式发电与SVG优化配置的调压方法

将静止无功发生器(SVG)引入到含有分布式发电的配电网中来调节电压。基于链式均匀配电网络、恒功率静态负荷模型和分布式电源的功率模型,采用叠加原理,分别考虑系统电源和分布式电源对配电网电压的作用,给出了分布式发电引入配电网后电压分布的计算方法。通过该方法,计及允许偏差,推导出分布式发电投入与退出后的电压调节理论判据。在分布式发电投入与退出2种情况下,分别以电压处于允许电压偏差范围内为目标和以降低线损为目标,计算出了SVG的接入位置和容量,最后利用分布式发电与SVG优化配置调节配电网电压。仿真算例表明:该方法计算简便、中间步骤少、效果明显。     

The impact of single-phase grid-connected distributed photovoltaic systems on the distribution network using P-Q and P-V models

The gradual emergence of photovoltaic (PV) systems as the most common distributed generation interconnected with the electric power system calls for a detailed power flow analysis with different models especially in the evolving unbalanced active distribution network. This paper is an extension of a previous study carried out on the performance evaluation of a 10 kWp grid-connected PV system deployed in a school, with the grid providing a virtual storage and access to upstream markets. For increased adoption of such systems in the unbalanced distribution network, it is pivotal to understand the mode of operation and the type of connection to the system. This article presents an impact analysis of such utility interactive single-phase PV systems distributed on all the single-phase load nodes of the traditional IEEE-13 bus distribution test feeder. The PV distributed generation (PV-DG) can be modelled as constant P-Q or P-V nodes with varied impacts in power flow studies for the unbalanced active distribution network. Results from these models are compared in terms of their impacts on voltage profiles at load buses, voltage unbalance, equipment loading, power losses and the total number of iterations for a converged power flow solution.     

考虑通信缺失情景的光伏集群分散式电压控制方法

针对高渗透率分布式光伏接入配电网导致的电压越限问题,以及当前电力通信网络难以实现对接入光伏集中控制的现状,提出了一种光伏集群分散式电压控制方法。根据预测数据对配电网进行集群划分,采用集群间的协调控制策略,以电压越限量和网络损耗加权值最小为优化目标,基于交替方向乘子法进行优化计算。在集群间通信缺失的情景下,基于无功-电压控制曲线自主调节分布式电源逆变器的无功输出,即通过集群内的电压控制策略解决通信中断时发生电压越限的问题。以IEEE 33节点配电系统为例进行仿真分析,结果表明所提控制方法不仅对改善电压分布不均、降低网损、减轻控制器的计算负担具有积极的作用,还能在通信缺失的情景下具有良好的控制效果。     

Simultaneous placement of distributed generation and capacitors in distribution networks considering voltage stability index

With regard to widespread use of distributed generation in distribution network, its technical impacts in distribution network should be thoroughly analyzed. In this paper simultaneous placement of distributed generation (DG) and capacitor is considered in radial distribution network with different load levels. The objectives of the problem are reduction of active and reactive power loss, reduction of energy loss and improvement of voltage profile. Also effect of capacitor and DG on voltage stability improvement has been considered in the objective function. Memetic algorithm is used to find optimal solutions. This algorithm is combinatorial form of local search and genetic algorithm. The performance of the proposed method is assessed on a test distribution network.     

联网燃气轮机的动态特性分析

介绍了燃气轮机发电机组及其励磁系统和调速系统的数学模型,并在MATLAB中建立了燃气轮机励磁系统的仿真模型,对其动态特性进行了仿真计算.利用电力系统分析综合程序(PSASP 6.1版)建立了燃气轮机励磁系统及调速系统的用户自定义模型,并结合典型配电网,对并网后的燃气轮机进行了暂态分析和小干扰稳定分析计算,分析了励磁系统及调速系统的有关参数对燃气轮机动态特性的影响,为研究分布式电源对电力系统暂态特性的影响奠定了基础.     

含分布式发电的有源配电网电压稳态指标计算研究

针对分布式电源接入配电网带来的电压静态稳定性问题,主要研究含分布式发电的有源配电网电压稳定性。首先提出了根据潮流解来计算整个配电网的电压稳定性指标方法以反映系统各节点的电压稳定性,然后考虑分布式发电作为一个负的负荷直接注入,分别建立了不同类型分布式电源在配电网潮流计算的模型。最后,以分布式电源中典型风电为例,对IEEE-33节点有源配电网进行仿真,分析了不同风机出力、风机接入及有功出力波动对有源配电网系统电压稳定的影响,仿真实验表明分布式电源的接入可以有效提高系统的电压稳定性。     

基于无模型自适应控制的配电网电压控制方案

新型电力系统下分布式新能源、分布式发电、电动汽车等新型元素大规模发展,配电网电压控制将面临控制对象特性异构、模型复杂、场景多变等挑战。在此背景下,文中提出一种基于无模型自适应控制的配电网电压控制方案。该方案在配电网电压控制分区及主导节点选取的基础上,利用主导节点电压、分布式电源以及储能装置出力等数据建立实时动态线性化数据滚动池,基于特征模型理论和数据驱动,将复杂系统电压控制特性通过控制器特征参数进行时变修正,在不损失系统模型信息的基础上降低了控制模型复杂程度。最后,通过改进的IEEE 33节点配电网系统算例进行仿真分析和对比,结果证明了所提控制方案的有效性。相较于传统的基于模型的控制方法,所提控制方案能够更快速地响应扰动带来的电压波动问题,应用前景良好。     

Assessment of Switched Communication Network Availability for State Estimation of Distribution Networks With Generation

Active management of complex distribution networks with distributed generation requires state estimation. As complete supervisory control and data acquisition systems are seldom available on 11-kV or lower voltage distribution networks, real-time measurements at remote points on 11-kV distribution networks are expensive. Therefore, the economical selection of a communication system for active management of distribution networks with distributed generation becomes an important issue. This paper presents the investigations into a leased communication system made of public-switched communication network channels for a distribution network state estimation application. It analyzes the effects of a different number of primary channels for real-time measurements on the distribution network state estimation accuracy. The leased communication system availability performance has also been analyzed and used to identify a number of reserve channels required to improve the leased system availability. The overall cost for improving the leased communication system availability has been calculated and compared with both a fiber-optic communication system and a power-line carrier communication system. The results show that the leased communication system is able to provide the lowest overall cost performance for the distribution network state estimation application.     

计及分布式电源输出特性的有源配电网重构方法

针对含分布式电源的配电网重构算法将分布式电源等效为恒功率因数输出模型,未考虑节点电压变化对分布式电源无功出力影响的问题,提出一种考虑分布式电源不同输出特性的配网重构方法。首先对分布式电源进行分类并建立等效模型,该模型充分考虑了节点电压对分布式电源无功出力的影响,能够根据节点电压确定不同属性的分布式电源无功出力。再使用自适应烟花算法对配网重构进行寻优求解,对重构后的系统网损和节点电压进行对比分析。含分布式电源的IEEE 33节点典型测试系统的仿真结果对比验证了所提模型的有效性和真实性。     

主动配电网低压分布式光伏连锁故障分析

分布式光伏发电系统大规模离散式接入配电网的趋势日益明显,电网节点光伏渗透率升高,功率传输流向发生改变,影响配电网电压分布。含分布式光伏发电系统的主动配电网模型通常是在单一节点处并联等效光伏电源模型,难以体现分布式电源离散性分布的特点。为此,建立含低压分布式光伏发电系统的主动配电网仿真模型,模拟低压分布式光伏系统脱网所引发的配电网电压波动以及各节点分布式电源连锁故障。基于牛顿-拉夫逊法潮流计算原理,提出关于节点功率变化对配电网电压分布影响的分析方法;仿真结果表明,低压分布式光伏发电系统连锁故障的分析方法能够较为准确地描述相应主动配电网在电压跌落情况下的连锁故障情况。     

基于遗传算法和微分进化算法的分布式电源优化配置

配电系统中,分布式电源（DG）安装位置的选择、额定容量的确定对于电网规划、设计和投资至关重要,以10节点配电网系统为例,采用遗传算法和微分进化算法对分布式电源进行了优化配置,建立了DG的不确定性模型,并将其加入到优化分析中,给出了优化算法的求解程序。对含DG的配电网进行了潮流计算,分析了DG容量与系统总网损的关系。算例分析结果表明,优化配置有效改善了配电网的电压分布,减小了网损,提高了系统负荷率,说明了该优化配置方法合理、有效。     

不平衡主动配电网电压无功两阶段多目标鲁棒优化

高间歇性分布式电源大量接入、线路排布不对称、负荷分布不均匀等因素加剧了配电网的三相不平衡。同时,分布式电源和负荷的显著不确定性导致配电系统电压越限频繁以及网络能量损耗增加。引入电压不平衡度二阶锥约束,以降低主动配电网的三相不平衡程度;采用鲁棒优化方法对分布式电源与负荷的不确定性进行建模;在此基础上,提出一种不平衡主动配电网的两阶段多目标电压无功控制模型,以最小化系统电压偏差和网络能量损耗;结合二阶锥松弛与线性化技术将非凸模型转化为可求解形式,利用法线边界相交算法处理多目标问题,并采用列与约束生成算法将可求解模型分为主问题与子问题进行迭代求解,从而得到鲁棒帕累托最优解。基于澳大利亚某真实配电网验证所提方法的有效性和鲁棒性。     

基于改进粒子群算法的含DG配电网无功优化

含分布式电源(DG)配电网的无功优化是一个复杂的非线性优化问题,文中采用改进的粒子群算法(PSO)对配电网进行无功优化计算,建立以系统网损和电压平均偏离最小为目标函数,节点电压和电容器投切容量为约束条件的优化模型。在PSO中引入位置方差防止PSO陷入局部最优解,根据种群中粒子的适应度值对粒子进行变异处理,在保证算法收敛速度的基础上,改善算法性能。以含分布式电源的IEEE14节点配电系统为例进行无功优化分析,结果表明DG能增强电网运行的稳定性,所提算法具有较好的优化性能。     

Impact of distributed generation on transient‐based fault location techniques in distribution networks

This paper demonstrates the effect of conventional distributed generation (DG) on fault location techniques based on transient signal analysis. DG penetration in distribution networks deviates the route‐specific frequencies generated by fault traveling waves propagating along the feeders and laterals. The amount of these deviations is proportional to the rated power of a certain DG unit. A validated fault location procedure is used to clarify this effect. Fault‐generated voltage transient signals are analyzed using continuous wavelet transform (CWT). These signals are captured by a recording device generally placed at the main feeder supplying the distribution systems. The route‐specific frequencies are acquired by the wavelet amplitude spectrum of transient signals. Using this technique, the relevance between the CWT‐recognized specific frequencies and those attained by mathematical definition determines the fault position. A six‐bus radial test distribution feeder is simulated within the EMTP‐RV program, and analysis of relevant transient signals is carried out using MATLAB programming language. © 2015 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

基于改进蚁狮优化算法的可再生能源分布式电源优化配置

分布式电源的合理规划能够降低配电网的功率损耗,针对可再生能源分布式电源规划配置问题,提出了一种基于改进蚁狮优化算法的可再生能源分布式电源优化配置方法。所提方法建立了以最小化实际功率损耗和改善配电网电压分布与电压稳定性为目标的多目标函数;利用改进蚁狮优化算法,通过模仿自然界中蚁狮的狩猎行为,统筹考虑损耗敏感系数和电压敏感系数,推导出不同类型的分布式电源单元的最佳总线位置和容量;以IEEE-33总线径向分布系统进行了仿真实验。实验结果表明,与其他算法相比,所提算法在降低功率损耗和电压分布方面更优,从而验证了所提算法的适应性和有效性。     

An efficient hybrid method for solving the optimal sitting and sizing problem of DG and shunt capacitor banks simultaneously based on imperialist competitive algorithm and genetic algorithm

Nowadays due to development of distribution systems and increase in electricity demand, the use of distributed generation (DG) sources and capacitors banks in parallel are increased. Determining the installation location and capacity are two significant factors affecting network loss reduction and improving network performance. This paper, proposes an efficient hybrid method based on Imperialist Competitive Algorithm (ICA) and genetic algorithm (GA) which can greatly envisaged with problems for optimal placement and sizing of DG sources and capacitor banks simultaneously. The objective function is power loss reduction, improving system voltage profile, increasing voltage stability index, load balancing and transmission and distribution relief capacity for both utilities and the customers.The proposed method is implemented on IEEE 33 bus and 69 bus radial distribution systems and the results are compared with GA/Particle swarm optimization (PSO) method. Test results show that the proposed method is more effective and has higher capability in finding optimum solutions.     

Optimal reactive power control of DGs for voltage regulation of MV distribution systems using sensitivity analysis method and PSO algorithm

This paper addresses the problem of reactive power control of distributed generation (DG) units in the medium voltage (MV) distribution systems to maintain the system voltages within the predefined limits. An efficient approach for the load flow calculation is used here which is based on the topological structure of the network. It has been formulated for the radial distribution systems. A direct voltage sensitivity analysis method is developed in this paper which is also based on the topological structure of the network and independent of the network operating points. Thus, the sensitivity matrix is calculated once with the load flow program and it is used in all the system working conditions. The problem of DGs reactive power control is formulated as an optimization problem which uses the sensitivity analysis for linearizing the system around its operating points. The objective of the optimization problem is to return the system voltages inside the permitted range by using the reactive power of DGs in an optimal way. The optimal solutions are obtained by implementing particle swarm optimization (PSO) algorithm. Then, the results are verified by running a load flow considering new values of DGs reactive power. The procedure is repeated as long as a voltage violation is observed. Simulation results reveal that the proposed algorithm is capable of keeping the system voltages within the permitted limits.     

分时电价提升配电网光伏消纳能力多目标优化策略

高比例分布式光伏接入配电网引起电压越限等问题限制了配电网的光伏消纳能力,为此建立了用于提升配电网光伏消纳能力的优化模型。首先,分析分布式光伏接入对配电网电压分布的影响;其次,建立分时电价优化模型和分布式光伏接纳优化模型用于提升配电网光伏消纳能力。分时电价优化模型为基于分时电价提升用户用电功率和降低用户用电成本的多目标优化模型,约束条件包括用户用电功率约束和电价约束;分布式光伏接纳优化模型基于分时电价优化模型计算结果,目标函数为配电网光伏消纳量最大,约束条件包括分时电价优化模型计算得到的配电网用电负荷和线路潮流约束。最后,以某一实际配电网系统为算例,计算结果表明经过2个模型优化后配电网可以有效提升光伏消纳能力。     

Improved fault location algorithm for radial distribution systems with discrete and continuous wavelet analysis

This paper presents a novel wavelet based approach for fault location using voltage transient waveforms in power distribution systems. The proposed method includes two main stages. Firstly, the approximate location of the fault or fault section is determined using a new algorithm with discrete wavelet transform. The difference between arriving times of transient components in different measurement units is used for this purpose. The accurate location of the fault is determined in the second stage. Depending on the determined fault section, the difference between arriving times of transient components in different measurement units or the frequency content of the voltage transients are used. The time difference and frequency content are calculated using discrete and continuous wavelet transform (DWT and CWT) respectively. The proposed technique is implemented on an unbalanced 34 bus distribution system with two distributed generation units which is simulated in ATP–EMTP. The comparison of the results of the proposed method with previous works verifies its better accuracy and more robustness to fault conditions including fault inception angle and fault resistance.