一种用于含风电场电力系统电压稳定概率分析的混合方法

为了进行风电并网后电力系统电压稳定性的评估,利用具有概率特征的负荷裕度指标,提出了一种含风电场电力系统电压稳定概率分析的混合方法.当系统随机参数扰动量很小时将系统简化为线性化模型,根据线性方程的叠加性原理,在计算负荷裕度关于随机参数的灵敏度矩阵的基础上运用叠加性原理并结合正态分布的特性,将系统负荷裕度在期望值附近的随机扰动分解为单独考虑负荷随机变化和风速随机变化两种情况下求得的负荷裕度扰动量之和.该方法与Monte Carlo法和半不变量法同时在IEEE-30节点系统上进行仿真计算,通过对比分析表明了本文方法在保证准确性的基础上节省了计算时间.     

一种用于含风电场电力系统电压稳定概率分析的混合方法

为了进行风电并网后电力系统电压稳定性的评估,利用具有概率特征的负荷裕度指标,提出了一种含风电场电力系统电压稳定概率分析的混合方法。当系统随机参数扰动量很小时将系统简化为线性化模型,根据线性方程的叠加性原理,在计算负荷裕度关于随机参数的灵敏度矩阵的基础上运用叠加性原理并结合正态分布的特性,将系统负荷裕度在期望值附近的随机扰动分解为单独考虑负荷随机变化和风速随机变化两种情况下求得的负荷裕度扰动量之和。该方法与Monte Carlo法和半不变量法同时在IEEE-30节点系统上进行仿真计算,通过对比分析表明了本文方法在保证准确性的基础上节省了计算时间。     

智能接地配电系统

为了发挥中性点非有效接地配电网供电可靠性高的优越性,提出了一种通过在变电站配置智能接地装置并在馈线配置具有零序保护功能的配电终端和故障指示器,将配电网升级为智能接地配电系统的方法。发生单相接地时,智能接地装置可以迅速将故障相短暂金属性接地从而可靠熄灭电弧。若为永久性接地故障,随后控制中性点短暂投入中电阻以显著增大接地点上游的零序电流并基于配电终端和故障指示器处配置的零序电流保护可靠地实现单相接地选线、定位和隔离。论述了智能接地配电系统的组成和关键技术,重点论述了通过电阻分级开关应对选相错误并抑制开关操作引起的系统暂态过程的方法。结合实例论证了所建议的方法的可行性和有效性。     

一种谐振接地系统的配电线路接地故障选线新方法

为解决小电流接地系统中发生故障时选线准确率低的问题,提出一种谐振接地系统单相接地故障选线新方法。通过分析不同线路的零序电流与零序阻抗特征,发现健全线路的零序阻抗始终呈容性,零序电流为纯容性电流;而故障线路零序电流在低频段含有消弧线圈的感性分量,且幅值大于高频段。先使用低通滤波器提取母线零序电压和各馈线零序电流在低频段的信号分量,并对母线零序电压求导;然后比较任意两条线路的零序电流与纯容性电流交叉相乘后乘积的差值,差值最大的为故障线路。分别对不同工况下的单相接地故障进行了仿真验证,结果表明,该方法选线准确,适应性强。     

小电流接地电网单相接地故障的小波选线方法

中性点非有效接地配电网发生单相接地故障时 ,尽快选出故障线路对电网运行有重要意义 ,但选线问题迄今尚未能很好解决。在分析了小电流接地电网发生单相接地时暂态特征的基础上 ,提出应用小波变换提取故障暂态信息 ,实现故障选线的方法。由于利用暂态量 ,该方法适应性、灵敏性均优于现有的基于稳态量方法。     

小电流接地电网单相接地故障的小波选线方法

中性点非有效接地配电网发生单相接地故障时,尽快选出故障线路对电网运行有重要意义,但选线问题迄今尚未能很好解决。在分析了小电流接地电网发生单相接地时暂态特征的基础上,提出应用小波变换提取故障暂态信息,实现故障选线的方法。由于利用暂态量,该方法适应性、灵敏性均优于现有的基于稳态量方法。     

Proper grounding of on-site electrical power systems

There are a number of factors that should be considered when grounding on-site power systems. Simply conforming to minimum code requirements will not necessarily assure the degree of reliability required for such systems. Thorough consideration should be given to protecting against power disruption within the building or facility and providing adequate ground-fault protection. Techniques for both equipment and system grounding should provide optimum safety and assure maximum continuity of power to essential loads. This includes proper grounding and ground-fault sensing when the transfer switch is in the emergency as well as normal position     

基于核随机逼近的概率风电预测方法

针对已有的参数化的风电概率预测方法存在的问题,即提前确定的预测模型不够精确导致预测性能不佳的问题,文中提出了一种基于核随机逼近和交替方向乘子法的非参数的概率风电预测方法,即基于核随机逼近的概率风电预测方法。在不预先假定真实预测模型的具体形式的情况下,该方法能逼近任何非线性预测模型。为了验证所提出方法的有效性和优越性,基于真实风电数据集,对所提出的方法以及参数化的方法就概率风电预测性能进行比较。实验结果显示前者的平均预测误差为0. 024 23,而后者的平均预测误差为0. 030 97,那么前者的预测性能优于后者,从而验证了所提出方法的有效性和优越性。     

Load supplying capability of interconnected power systems: A probabilistic approach

Prudent planning of a power system always requires determination of its load supplying capability (LSC). However, the assessment of the ability of a power system to supply loads can become very difficult when the problem data are uncertain. In this case the use of current deterministic approaches is not adequate and the application of probabilistic techniques is the most feasible alternative. This paper presents a probabilistic approach for the evaluation of the LSC of interconnected power systems in order to capture the unavoidable random nature of loads due to bus load forecasting. The method treats loads as random correlated variables with normal distribution and it can determine the probability distribution of the system LSC and of all the quantities which characterize the state of the network in this particular condition. A numerical example is included to illustrate the usefulness of the proposed technique.     

新型小电流接地故障选线装置的设计

在分析了小电流接地系统选线困难的主要原因的基础上,设计了一种针对暂态量算法的新型选线装置。该装置采用TMS320VC5402DSP为CPU,很好地满足了暂态算法对硬件的要求,实验表明本装置具有很好的应用价值。     

A new stabilizer design technique for multimachine power systems

A simple and systematic procedure for decentralized stabilizer design for multimachine systems is presented in this paper. The procedure first selects the most effective location of a stabilizer according to a machine stability index. The parameters of the stabilizer are then determined by a decentralized feedback control scheme. This process is carried out for one stabilizer at a time. The resultant overall improvement of the system stability, measured by a system stability index, is used to decide how many stabilizers are required for the system. The proposed technique is illustrated by a test system. Both eigenvalue analysis and nonlinear simulation are performed to investigate the effectiveness of the technique.     

新型小电流接地故障选线装置的设计

在分析了小电流接地系统选线困难的主要原因的基础上,设计了一种针对暂态量算法的新型选线装置.该装置采用TMS320VC5402 DSP为CPU,很好地满足了暂态算法对硬件的要求,实验表明本装置具有很好的应用价值.     

A new decentralized stabilization method with application to power system stabilizer design for multimachine systems

A new decentralized stabilization method is presented, in which l single-input/single-output local feedback controllers are designed to stabilize or to improve the stability of a large-scale system consisting of N subsystems with l<N negative or poorly damped system modes. The method is shown to be simple and feasible to apply to power system stabilizer design for multimachine systems. Further research work is suggested.     

一种高压直流输电系统接地极线路保护新方法

针对目前基于信号注入的接地极线路保护方法在某些故障情况下可能出现保护拒动的问题,提出一种基于频带电压幅值积分的接地极线路保护新方法。通过仿真分析发现在高压直流输电系统接地极线路故障后其首端电压频谱会出现明显变化,基于此提出一种利用小波包分析获取接地极线路首端电压不同频带分量,以频带电压幅值积分在一段时间内的变化为保护判据的接地极线路保护方法。基于PSCAD/EMTDC软件的大量仿真结果表明,该方法能有效检测到接地极线路上的各种故障,识别准确性不受过渡电阻的影响,具有良好的应用前景。     

A design method for continuous deadbeat control systems

Deadbeat control of discrete‐time systems has attracted particular interest because it ensures setting the deviation response to zero within finite time and affords fast responsiveness. By using controllers which include a delay element, however, the deadbeat characteristics can be realized in the continuous‐time domain, and such a tracking system has been obtained. In this paper, we propose a new design method of continuous deadbeat control systems without using delay elements. Our new controller is composed of a digital deadbeat compensator using state feedback and a series smoothing filter. Illustrative numerical examples are presented. The method proposed here is very simple compared with other methods and it seems to be useful for practical applications. © 1999 Scripta Technica, Electr Eng Jpn, 127(2): 42–48, 1999     

特高压和高压直流输电系统共用接地极模式分析

为了节省占地面积和建设费用,云广特高压直流输电系统和贵广二回高压直流输电系统在广东侧决定采用共用接地极模式。讨论了特高压和高压输电系统的共用接地极模式,对共用接地极的要求提出了设计方案。分析了共用接地极对2个直流输电系统的稳态运行、过电压绝缘配合以及控制保护系统的影响。结果表明:云广特高压直流输电系统和贵广二回高压直流输电系统共用接地极模式是可行的。     

The extremal charges method in grounding grid design

The behavior of the electric field in earth generated by a fault current derivation to a grounding grid can adequately be modeled by a Colombian potential that is constant in the grid and its reflected image with respect to the earth's surface. We aim here at approximating, in an efficient way, the charge distribution that produces this potential by using potential theory methods. First, we describe the extremal charges method that allows one to obtain an approximation to the charge distribution as the solution of an optimization problem, specifically a linear programming problem. Second, we show the accuracy of the method obtaining the potential and the fundamental parameters of a grid. Then, we describe a grid design optimization methodology. The optimal grid performance is the one that achieves the better agreement between the grid resistance and the touch and step voltages. Both parts are illustrated with graphical results showing the accuracy of this new method of grid analysis and design.