孤立发电系统的可靠性区间评估

考虑发电系统原始参数具有不确定性,结合概率论和区间运算概念,提出了一种孤立发电系统的可靠性区间评估方法.它不但可以处理可靠性原始参数的不确定性对发电系统可靠性指标的影响,还可以求出参数在一定范围内变化时的系统可靠性指标区间值,更能体现出系统可靠性的真实性.最后采用一个三机的算例对所提方法的正确性进行了验证,并对采用点值与采用区间数得到的发电系统可靠性评估结果进行了对比分析,进一步说明了该方法的有效性.     

实施需求侧管理对提高发电系统可靠性的影响探究

实施需求侧管理可以提高能源利用率,减少最大负荷需求量,相当于间接增加了系统的发电容量,因此能够提高发电系统的可靠性。简要介绍了发电系统可靠性指标,建立发电系统可靠性分析模型,包括发电容量模型和负荷模型,并分析了非时序蒙特卡洛法在发电系统可靠性评估中的应用。采用模拟法定量,以IEEE可靠性测试系统RTS(Reliability Test System)为例定量分析需求侧管理对发电系统可靠性的影响,分析结果表明实施需求侧管理能够提高能源利用率和发电系统的可靠性,使系统更加安全、经济、可靠地对用户供电。     

孤立发电系统的可靠性区间评估

考虑发电系统原始参数具有不确定性,结合概率论和区间运算概念,提出了一种孤立发电系统的可靠性区间评估方法。它不但可以处理可靠性原始参数的不确定性对发电系统可靠性指标的影响,还可以求出参数在一定范围内变化时的系统可靠性指标区间值,更能体现出系统可靠性的真实性。最后采用一个三机的算例对所提方法的正确性进行了验证,并对采用点值与采用区间数得到的发电系统可靠性评估结果进行了对比分析,进一步说明了该方法的有效性。     

基于元件强迫停运率的互联系统可靠性指标灵敏度分析

电力系统通过互联可以实现发电容量的相互支援,提高了各独立系统的可靠性水平.分析了新增发电容量和区域之间联络线的强迫停运率(FOR)对互联系统各区域可靠性的影响,提出了基于元件强迫停运率的区域发电可靠性指标灵敏度表达式:首先从理论上推导了互联系统多区域发电可靠性对于发电机组和联络线强迫停运率的灵敏度解析式,并分析机组和联络线FOR的不确定性对区域可靠性指标方差的影响;在此基础上根据区域备用容量变化与机组及联络线FOR变化之间的相互独立性,对互联系统指数解析模型进行修正.此模型可计及新增发电机组和区域之间联络线FOR变化,快速准确计算变化后的可靠性水平,并能够根据灵敏度的大小判断对系统可靠性影响较大的关键环节和薄弱环节,计算结果表明了修正指数解析模型的有效性.     

计及元件故障率时变特性的综合能源系统运行可靠性高效评估方法

为提高运行可靠性评估效率,进而支撑系统运行风险防控,基于模型-数据混合驱动的思想提出了一种计及元件故障率时变特性的综合能源系统运行可靠性高效评估方法。构建了基于复杂网络理论的支路脆弱度因子指标,提出系统关键元件的筛选方法。建立系统可靠性指标关于关键元件可靠性参数的解析模型,通过引入辅助变量建立线性优化模型求取解析模型系数。通过最小二乘支持向量机(LSSVM)回归模型获得运行可靠性解析模型与负荷水平的映射关系,实现负荷变化时系统运行可靠性的快速更新。通过算例测试验证了所提方法的计算效率和精度。     

利用多项式回归进行火电机组特性分析

以九江电厂125MW火电机组发电数据为基础,通过对不同负荷段下的运行数据进行数据异常检验及相关性分析,获取不具有相关性的运行参数作为样本数据,利用多元多项式建立了运行参数对发电煤耗的回归模型。通过对回归模型及回归系数的显著性检验及对实际生产数据的模拟,证明了分负荷段的回归模型是一种实用、有效的分析模型,能够反映机组的运行特性,为发电企业在模拟机组运行、科学预测发电煤耗及提高机组运行经济性方面提供了有效手段。     

计及分布式电源出力相关性的微电网发电系统可靠性评估

为了揭示分布式电源(DG)出力相关性对微电网发电系统可靠性的影响,利用Nataf概率变换原理和多重Gauss数值积分方法获得非标准正态分布相关关系的数学模型。在计及DG强迫停运、非线性出力等因素的基础上,建立了微电网发电系统可靠性评估模型,基于蒙特卡洛方法实现可靠性指标的求解。通过算例定量分析DG出力特性、微电网内DG总容量与负荷容量比、一次能源相关系数变化对微电网发电系统可靠性指标的影响,验证了所述模型和方法的有效性。     

基于序贯蒙特卡罗法的复杂配电网可靠性分析

光伏发电具有随机性和间歇性的特点,使得配电网的可靠性存在下行风险。针对含光伏电源的配电网系统,传统的可靠性评估方法往往忽略光伏系统对可靠性的影响。利用序贯蒙特卡罗法对配网进行可靠性分析,考虑太阳光辐照度、光伏输出功率、时序故障率等因素的影响,建立基于时间序列的光伏发电系统可靠性模型;同时构建了考虑负荷功率随机性的中、短期负荷（月、小时）可靠性模型;最后引入可靠性灵敏度指标,评估了不同节点接入光伏发电系统后的可靠性。通过对含光伏发电系统配电网算例系统的可靠性进行评估,结果证明了算法的有效性,该方法为光伏接入位置的选择、容量的确定和配网可靠性的提高提供了重要的理论依据。     

计及电池储能设备运行特性的风电场可靠性评估

在含电池储能设备风电场功率时序模型的基础上,建立了含功率型和能量型电池储能设备的风电场可靠性时序评估模型.使用 RBTS 发电系统作为算例,分析了2类电池设备在不同储能策略下对风电系统可靠性改善的程度,并进一步分析了储能设备自身的运行参数对风电系统可靠性影响.算例结果表明:在具有同样设备容量的情况下,3种储能策略对可靠性的改善不尽相同;在同一储能策略下,能量型电池储能设备对系统的可靠性改善更佳;同时,设备运行参数变化对系统可靠性指标也有一定的影响     

基于传输点容量模型的发输电系统可靠性评估

利用发输电组合系统(简称组合系统)极限输电能力与负荷解耦(系统—负荷解耦)的特性,能有效提高组合系统可靠性的评估效率。目前已有的基于系统—负荷解耦分析的组合系统可靠性评估方法尚存在不足,其中的输电能力计算模型没有考虑异常状态下优化负荷削减的实际需求,也没有计及各不同传输点负荷水平变化的影响,此外,对于频率及持续时间型可靠性指标的计算方法,目前也鲜有研究。该文以系统—负荷解耦分析为出发点,提出基于传输点容量模型的组合系统可靠性评估方法。首先,建立一种适用于组合系统可靠性分析的传输点输电能力优化决策模型,并针对该模型目标函数具有斜率递增的特点,将其转换为线性规划模型进行求解,保证计算效率。然后,拓展传统发电系统可靠性评估中可用容量状态概率及增量频率的概念,基于马尔科夫链构建组合系统各传输点输电能力的概率—频率分布函数(即传输点容量模型),将其与相应负荷的概率—频率分布函数(即负荷模型)进行卷积和加法运算,不仅能得到组合系统及其传输点的概率型可靠性指标,而且还能得到频率及持续时间型等可靠性指标。以RBTS-6节点系统为例进行测试分析,说明该方法的有效性。     

Comparison of two algorithms for power system reliability calculations

In this paper, two algorithms are proposed for the computation of the static generation reliability of a power system. The loss-of-load probability (LOLP), which is the reliability index usually employed in static generation reliability evaluation, is computed by using both the capacity outage table and effective load approaches. Numerical results obtained from the study of a sample power system consisting of 44 generating units are compared in terms of the required computational time and numerical accuracy. It is found that, with the generating capacities properly rounded off, the capacity outage table method can be employed as an effective means of computing power system reliability. The effect of generation expansion planning on generation reliability is also examined.     

需求弹性对发电系统可靠性的影响

在电力市场环境下,由于负荷需求弹性的存在,面对电价的波动,用户可适时调整负荷计划,改变实际负荷曲线,从而直接影响发电系统可靠性的计算。构筑考虑需求弹性的电价负反馈模型,通过对IEEE30节点系统进行计算,研究了需求弹性对发电系统可靠性的影响,也即对电源充裕度的影响。     

Reliability assessment of restructured power systems using reliability network equivalent and pseudo-sequential simulation techniques

This paper presents a technique to evaluate reliability of a restructured power system with a bilateral market. The proposed technique is based on the combination of the reliability network equivalent and pseudo-sequential simulation approaches. The reliability network equivalent techniques have been implemented in the Monte Carlo simulation procedure to reduce the computational burden of the analysis. Pseudo-sequential simulation has been used to increase the computational efficiency of the non-sequential simulation method and to model the chronological aspects of market trading and system operation. Multi-state Markov models for generation and transmission systems are proposed and implemented in the simulation. A new load shedding scheme is proposed during generation inadequacy and network congestion to minimize the load curtailment. The IEEE reliability test system (RTS) is used to illustrate the technique.     

Markov method for generating capacity reliability evaluation including operating considerations

A new approach is introduced for calculating the generation system reliability indices such as loss of load expectation, frequency of load loss and the mean duration. The Markov approach is used for modelling the generation and load to include the effect of operating considerations such as unit duty cycle, start-up failure probability and start-up delay. A computer program has been developed to implement the Markov approach. This method is compared with recursive techniques and a close agreement between the results is obtained.     

Scenario selection in composite reliability assessment of deregulated power systems

Power market analysis should be incorporated in reliability assessments of deregulated power systems. For the Nordic power system, this is done by using The Multi-area Power-market Simulator (EMPS) for long-term power market analysis, where EMPS finds the optimal socio-economic dispatch on a weekly basis, with respect to, e.g., hydro reservoir levels. The EMPS analysis results in a set of load and generation scenarios, and these scenarios are interpreted as a sample of future power market behaviour, and is used as basis for a reliability assessment. These load and generation scenarios are referred to as power market scenarios.The power market analysis produces a large number of power market scenarios, and to include all these scenarios in a reliability assessment results in excessive computation time. The scenario selection method is presented and discussed. Scenario selection is used to pick out a subset of the generated power market scenarios, to only use this subset of scenarios as a basis for the reliability assessment. The paper provides some general guidelines for application of the scenario selection method. It is shown that the scenario selection method can reduce the scenario set by about 90%, with little loss of accuracy in the reliability assessment.     

Dynamic system reliability study modeling

This article extends conventional reliability modeling to a comprehensive modeling to cover system dynamic response and plant process response as the consequence of system component failures. The study results indicate the load outages from system dynamic response and process response cannot be neglected-they may have significant contributions to the system load outages. The example system study shows the conventional reliability modeling covers about 50% of total load outages. This modeling provides a more realistic approach. The modeling also considers the component failure rate adjustment for effects of component age and maintenance quality. The modelling, using accumulations of system segment contributions to load outages, is a practical approach for industrial systems. The results of reliability evaluation in terms of load outage indices, segment contributions, and overall system reliability indices, provide valuable information for plant management decision making with respect to return-of-investment in system reliability improvement projects. The reliability modeling can be coordinated with other system planning studies, such as system expansion and redesign, because these studies usually require system load flow, short circuit and transient stability analysis. These studies are usually involved in the evaluations of many alternatives. With the reliability evaluations added into the system planning study, the results will be more valuable for decision making among many alternatives     

Development of power system reliability analysis program with consideration of system operation

This paper describes a new program which analyzes the reliability of composite power systems with consideration of power system operational aspects. It uses the sequential Monte Carlo method and calculates annual risk indices for each load point. The program deals with the system problems involved in load flow, voltage, frequency, and small‐signal stability if necessary. The distinctive feature of the program is consideration of power system operation in a sequential manner, such as generation dispatch and system restoration after equipment failure. This makes possible the evaluation of both power system planning and operation from the reliability point of view. Several new methods of reducing calculation time are developed and implemented, including the concurrent LP/load flow method, which improves solvability. © 2005 Wiley Periodicals, Inc. Electr Eng Jpn, 153(4): 20–31, 2005; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20138     

Security modeling for power system reliability evaluation

This paper presents conceptual development, computation procedure and simulation results of the methodology for modeling security within reliability evaluation of power systems. The proposed approach takes into account activation of protection and automatic controls, local actions of operators, as well as centralized decisions taken by system operators. Transient stability, frequency variation during governor control, emergency and normal levels of line thermal protection, automatic generation control, overload rotation and economic dispatch are the main points of the developed procedure. It can be directly incorporated into the hybrid model for reliability evaluation of different operating states