电力系统静态安全混合控制方法

提出一种将预防控制和校正控制相协调的电力系统静态安全混合控制方法。预防控制模块中,利用风险指标确定进入预防控制模块的预想故障集,该风险指标考虑了预想故障发生的概率及其严重性,采用连续线性规划技术求解考虑多预想故障的静态安全预防控制策略。校正控制模块中,首先判断系统静态安全裕度是否满足要求,并考虑风电/光伏的随机波动特性,针对不安全故障分别制定校正控制策略。所提方法通过系统风险指标协调预防控制和校正控制中考虑的预想故障集,从而将预防控制和校正控制相互协调,以获得安全性和经济性均满足系统需求的静态安全控制策略。以我国某682节点系统的算例验证了所提方法的有效性。     

Economic dispatch with security-constrained rescheduling

A mathematical framework is described for the solution of the economic dispatch problem with security constraints, which can take into account the system corrective capabilities after an outage has occurred. The solution algorithm is based on mathematical programming decomposition techniques that allow the iterative solution of a ‘base-case’ economic dispatch and separate contingency analysis with generation rescheduling to eliminate constraint violations. The resulting dispatch has the same security level as the usual security-constrained dispatch, but with lower operating costs. Case studies with the system of Southern Brazil are presented. The extension of the methodology to include other corrective schemes is also discussed.     

安全有功实时调度在云南电网AGC中的应用

介绍了云南省调EMS中的安全有功实时调度系统,该系统将自动发电控制与安全约束调度结合在一起构成闭环控制,实现电网稳定断面越限的预防和校正控制。实际工程应用表明,该方法是有效的、可行的。     

ANN based integrated security assessment of power system using parallel computing

This paper presents the application of cascade neural network (CANN) based approach for integrated security (voltage and line flow security) assessment. The developed cascade neural network is a combination of one screening module and two ranking modules, which are Levenberg–Marquardt Algorithm based neural networks (LMANNs). All the single line outage contingency cases are applied to the screening module, which is 3-layered feed-forward ANN having two outputs. The screening module is trained to classify them either in critical contingency class or in non-critical contingency class from the viewpoint of voltage/line loading. The screened critical contingencies are passed to the corresponding ranking modules, which are developed simultaneously by using parallel computing. Parallel computing deals with the development of programs where multiple concurrent processes cooperate in the fulfillment of a common task. For contingency screening and ranking, two performance indices: one based on voltage security of power system (VPI) and other based on line flow (MWPI) are used. Effectiveness of the proposed cascade neural network based approach has been demonstrated by applying it for contingency selection and ranking at different loading conditions for IEEE 30-bus and a practical 75-bus Indian system. The results obtained clearly indicate the superiority of the proposed approach in terms of speedup in training time of neural networks as compared to the case when the two ranking neural networks were developed sequentially to estimate VPI and MWPI.     

阻塞管理和电压安全

电力市场下的阻塞管理与系统电压安全密切相关。采用将最优潮流与连续潮流相结合的方法解决阻塞问题,并使系统运行在电压安全裕度之内。提出两种算法结合迭代求解流程．并用步长函数描述连续潮流法CPF(Continuation Power Flow)中的步长选择过程。IEEE-30节点和IEEE-57节点系统的结果表明,所提方法可避免或减轻网络阻塞,且不危及系统的电压安全裕度。     

Optimal location and parameter setting of UPFC for enhancing power system security based on Differential Evolution algorithm

This paper presents a new approach based on Differential Evolution (DE) technique to find out the optimal placement and parameter setting of Unified Power Flow Controller (UPFC) for enhancing power system security under single line contingencies. Firstly, we perform a contingency analysis and ranking process to determine the most severe line outage contingencies considering line overloads and bus voltage limit violations as a Performance Index. Secondly, we apply DE technique to find out the optimal location and parameter setting of UPFC under the determined contingency scenarios. To verify our proposed approach, we perform simulations on an IEEE 14-bus and an IEEE 30-bus power systems. The results we have obtained indicate that installing UPFC in the location optimized by DE can significantly enhance the security of power system by eliminating or minimizing the overloaded lines and the bus voltage limit violations.     

Fast voltage contingency screening using radial basis function neural network

Power system security is one of the vital concerns in competitive electricity markets due to the delineation of the system controller and the generation owner. This paper presents an approach based on radial basis function neural network (RBFN) to rank the contingencies expected to cause steady state bus voltage violations. Euclidean distance-based clustering technique has been employed to select the number of hidden (RBF) units and unit centers for the RBF neural network. A feature selection technique based on the class separability index and correlation coefficient has been employed to identify the inputs for the RBF network. The effectiveness of the proposed approach has been demonstrated on IEEE 30-bus system and a practical 75-bus Indian system for voltage contingency screening/ranking at different loading conditions.     

基于电压稳定预想事故的快速输电能力分析

以连续潮流技术为基础,提出了考虑鞍点分叉造成的静态电压稳定性约束下的电力系统输电能力的快速分析与计算。考虑到输电线路和发电机故障对系统静态电压稳定性的影响,以电压稳定性指标进行预想事故选择,并用连续潮流法计算得到N-1安全约束下的系统输电能力。经过IEEE 9节点和30节点算例的分析,表明此方法是简洁,快速和可靠的。     

江苏电网AGC安全约束控制的实现与应用

阐述了利用安全约束调度进行自动发电控制(AGC)安全约束控制的实现技术及应用。当系统处于紧急状态或预警状态时,AGC根据实时安全约束调度提出的机组调整方案和灵敏度信息,通过限制机组AGC调节上下限或限制机组AGC调节方向,执行稳定断面越限的校正控制和预防控制。实践表明,AGC安全约束控制可有效消除和缓解了电网稳定断面的越限,提高电网的安全稳定水平。     

Multi-objective optimization operation with corrective control actions for meshed AC/DC grids including multi-terminal VSC-HVDC

This paper presents a multi-objective optimal operation of meshed AC/DC power grids including multi-terminal voltage-source-converter-based high-voltage direct current (VSC-MTDC) systems. The proposed approach is modeled as a corrective security-constrained optimal power flow (CSC-OPF) problem, with the minimization of both the operation cost and power loss as the objectives. Moreover, it provides a cost-effective solution to assist in decision-making, and improves the system security during operation. The N − 1 contingency security criterion is enforced for both AC and DC transmission networks, and corrective control is used to eliminate or alleviate post-contingency security violations. The corrective control actions used in this paper include not only secure operation control actions, but also economical post-contingency corrective control of the multi-terminal VSC-HVDC. To increase the computation speed, a contingency screening technique is applied to CSC-OPF by efficiently selecting the most severe case of the N − 1 contingency, as obtained using a voltage security index (VSI). The proposed approach uses the non-dominated sorting genetic algorithm (NSGA-II) to find multi-objective OPF solutions by checking the post-contingency state feasibility while taking into account post-contingency corrective actions. Simulation results confirm the validity and effectiveness of this approach.     

能源互联网中基于多微网校正控制的安全约束最优潮流

近年来,能源互联网因其具有双向按需传输和智能分配能源的优点受到了高度重视。基于Benders分解的求解算法,提出了在能源互联网中通过多微网实现校正控制的安全约束最优潮流模型;在此基础上,提出了利用协调多个微网和系统机组解决故障后线路过载的激励控制策略。不同于直接负荷控制,该方法能够更好地促进主网与多微网之间的双向潮流以利于故障后电网的恢复。通过IEEE118节点标准系统验证了模型与算法的可行性与有效性。     

Estimation of synchronous machine parameters using new discrete time-filtering algorithm

This paper presents a new method for estimating synchronous machine parameters from frequency test using a discrete time-dynamic filter based on the least absolute value parameter estimation algorithm (see G.S. Christensen and S.A. Soliman, Automatica. 26 (2) (1990) 389–395). The proposed method uses a digital set of measurements for the direct axis impedance magnitude and phase as a function of the frequency for estimating the d-axis parameters, such as the direct reactance and the different direct axis time constants, as well as the q-axis parameters.A practical example from the literature is used (see F.B. De Mello and L.N. Hannet, IEEE Trans. Power Appar, Syst., PAS-102 (12) (1983) 3810–3815) to test the proposed algorithm, and results are obtained and compared with those obtained using other methods such as the least error squares algorithm (see S.A. Soliman, S.E. Emam and G.S. Christensen, Can. J. Electr. Comput. Eng., 14 (3) (1989) 98–102) and the Kalman filtering algorithm (see M. Mambo, T. Nishiwaki, Syokokawa and Y. Ueki, IEEE Trans Power Appar. Syst., PAS-100 (7) (1981) 3304–3311).     

Comprehensive reliability assessment of substation originated outages using the Monte Carlo simulation technique

Power system security and stability has become a major concern for electric power utilities, as power systems become more and more complex and are operated closer to transmission capacity limits. Substations and switching stations are pivotal parts of power systems. Failure events in substations often result in multiple outages of generators, lines, and/or loads in power systems, and affect the security and stability of power system dramatically. The reliability evaluation of substation originated outages is therefore of vital importance. This paper presents the application of a Monte Carlo simulation (MCS) method to the reliability evaluation of voltage step-up substations and switching stations (herein referred to only as substations) in transmission systems. The proposed approach is demonstrated by application to an educational test system designated as RBTS (R. Billinton, S. Kumar, L. Goel, et al., A reliability test system for educational purposes—basic data, IEEE Trans. Power Appar. Syst. 4 (3) (1989) 1238–1244) and some selected sensitivity studies are also presented in this paper. The results of studies provide valuable information for decision-making in power system planning and operation. A comparison between the reliability indices of two groups of overlapping failures obtained from both analytical method and MCS approach shows that the approximate equations of analytical methods have constraints when the component average repair time exceeds certain numerical range. The MCS approach is shown to be more accurate when dealing with the multiple order outages.     

计及动作安全裕度的节点电压脆弱性评估

针对电力系统安全问题,定义了节点动作安全裕度指标,结合传统节点电压脆弱性评估指标,对预想事故下的节点电压脆弱性进行分析,建立了计及动作安全裕度的节点电压脆弱性评估指标。通过对IEEE14、IEEE30母线系统的仿真,结果表明节点事故动作安全裕度的引入部分改变了传统节点电压脆弱度的排序,与传统节点电压脆弱性评估结果相比,更全面考虑了事故发生概率以及事故保护作用和故障操作对节点脆弱性的影响,提高了不同事故下节点电压脆弱性的评估精度,验证了该方法的和合理性与有效性。     

考虑风电接入的在线风险评估和预防控制

随着风电渗透率日趋提高,大规模风电的接入对电网静态电压安全的影响也逐渐增强,风电出力分钟级的显著变化将导致电网运行状态的频繁波动,甚至出现静态电压失稳的可能。为应对该问题,提出考虑大规模风电接入的在线电网静态电压安全风险指标,并搭建基于此风险指标的预防控制模型以降低系统运行风险,提高系统稳定运行裕度。IEEE 9节点系统和IEEE 39节点系统验证了所提风险指标和预防控制模型的有效性。     

Preventive/corrective control for voltage stability using directinterior point method

This paper describes the applications of the interior point (IP) method on preventive/corrective control (PCC) for voltage stability. The mathematical model of preventive/corrective control, based on the control costs, is proposed. In the real time mode, the preventive control is carried out when the voltage stability margins between the operating point and the stability boundary are too small. In the study mode, the corrective control is carried out when the voltage is insecure. After preventive/corrective control, not only should the system operation point be in the voltage secure area, but some voltage stability margins should also be maintained. The approach proposed has been successfully tested on five systems-from 100 bus system to 4000 bus system     

On complete stability of linear and quadratic programming neural networks

The paper addresses complete stability (CS) of the important class of neural networks to solve linear and quadratic programming problems introduced by Kennedy and Chua (IEEE Trans. Circuits Syst., 1988; 35 : 554). By CS it is meant that each trajectory converges to a stationary state, i.e. an equilibrium point of the neural network. It is shown that the neural networks in (IEEE Trans. Circuits Syst., 1988; 35 : 554) enjoy the property of CS even in the most general case where there are infinite non‐isolated equilibrium points. This result, which is proved by exploiting a new method to analyse CS (Int. J. Bifurcation Chaos 2001; 11 : 655), extends the stability analysis by Kennedy and Chua (IEEE Trans. Circuits Syst., 1988; 35 : 554) to situations of interest where the optimization problems have infinite solutions. Copyright © 2002 John Wiley & Sons, Ltd.     

Classification and assessment of power system static security using decision tree and random forest classifiers

The power system static security classification and assessment is essential in order to identify the post‐contingency problems and take corrective measures and to protect the system from blackout. In this paper, application of two data mining classifiers have been proposed for the security classification and assessment of a multiclass security problem. To design the security problem, contingency analysis is carried out under N‐1 line outage, and static severity index (SSI) is computed, which is a function of the line overload and the voltage deviation using Newton–Raphson load flow method, considering the variable load and generating conditions. Corresponding to the computed values of SSI, the voltage, phase angle, Mega Volt Ampere line flow and so on, a 1 × 7 pattern vector is generated. The generated pattern vectors are used to design a multiclass security problem. The designed security pattern vectors are given as inputs to the decision tree (DT) and random forest (RF) model in order to classify the security status of the power system. The proposed classifiers are investigated on an IEEE 30‐bus test system. The classification accuracy of the DT and the RF are compared with state‐of‐the‐art classifier models, namely, multilayer perceptron (MLP), radial basis function (RBF), and support vector machine (SVM).The simulation results clearly indicate that the proposed DT and RF classifiers are more efficient, reliable, and out performs MLP, RBF, and SVM classifiers for the assessment of the security status of the power system. Hence, DT and RF classifiers are found to be suitable for online implementation. Copyright © 2015 John Wiley & Sons, Ltd.     

考虑柔性交流输电系统设备控制的校正型安全约束最优潮流

为提升安全约束最优潮流调度的经济性与安全性,提出一种基于直流潮流的考虑柔性交流输电系统(FACTS)设备控制的校正型安全约束最优潮流模型。在线路故障发生后,通过FACTS设备校正措施,将线路潮流控制在其容许范围内。由于所提模型为大规模的非凸、非线性优化问题,难以直接求解,因此先采用大M法,将原非线性优化模型转换为混合整数线性规化模型,并采用Benders分解算法将转换后的模型分解为基态最优潮流主问题与N-1故障校验子问题。通过固定整数变量的方法,将非凸的混合整数优化子问题转换为线性规划子问题,从而能向主问题返回对应的Benders割。6节点系统与IEEE RTS-79节点系统算例验证了所提模型与算法的有效性。结果表明,考虑FACTS设备校正控制的安全约束最优潮流能有效提升调度运行的经济性。     

A corrective control for angle and voltage stability enhancement onthe transient time-scale

This paper deals with the development of a nonlinear programming methodology for evaluating load shedding (LS) as a corrective action to improve the dynamic security of power systems when angle or voltage instability is detected. A centralized corrective control is developed, on the basis of online DSA computations, in order to ensure corrective actions when a threatening contingency actually occurs. The algorithm is implemented and tested on the actual Italian grid managed by ENEL S.p.A