电力系统局部电路谐波谐振产生原因分析及对策

对在谐波源产生的谐波作用下,电力系统局部电路发生串、并联谐振的原因进行深入分析,论述了电力系统运行中较常见的电磁式电压互感器铁芯饱和引起的谐波谐振的发生原理,针对谐波谐振过电压的危害提出了预防和应对措施,通过减少谐波源,限制注入电网的谐波电流和采取措施使系统参数处于谐振范围之外来预防和抑制谐波谐振的发生.     

电力系统局部电路谐波谐振产生原因分析及对策

对在谐波源产生的谐波作用下,电力系统局部电路发生串、并联谐振的原因进行深入分析,论述了电力系统运行中较常见的电磁式电压互感器铁芯饱和引起的谐波谐振的发生原理,针对谐波谐振过电压的危害提出了预防和应对措施,通过减少谐波源,限制注入电网的谐波电流和采取措施使系统参数处于谐振范围之外来预防和抑制谐波谐振的发生。     

基于松弛牛顿法的配电网潮流计算方法

配电网潮流的分析计算是配电自动化系统中的一项最基本的高级应用功能.将矩阵求逆运算的松弛方法应用于配电网的潮流计算,并利用矩阵分裂法,导出了一种新的配电网潮流计算算法.导出的算法具有通用性,既可用于放射形配电网,又适用于含有环网的一般配电网络.算法的求解过程简单、快捷,无需直接形成和计算雅可比矩阵、无需三角因子分解等过程,直接由前代/回代或回代/前代过程就能完成.以一个实际的中等规模配电系统为例,测试、分析和比较了算法的收敛性和计算速度,证实了所提算法的有效性.     

基于松弛牛顿法的配电网潮流计算方法

配电网潮流的分析计算是配电自动化系统中的一项最基本的高级应用功能。将矩阵求逆运算的松弛方法应用于配电网的潮流计算,并利用矩阵分裂法,导出了一种新的配电网潮流计算算法。导出的算法具有通用性,既可用于放射形配电网,又适用于含有环网的一般配电网络。算法的求解过程简单、快捷,无需直接形成和计算雅可比矩阵、无需三角因子分解等过程,直接由前代/回代或回代/前代过程就能完成。以一个实际的中等规模配电系统为例,测试、分析和比较了算法的收敛性和计算速度,证实了所提算法的有效性。     

灵敏度方法在电力系统分析与控制中的应用综述

灵敏度是利用系统中某些物理量的微分关系,来获得因变量对自变量敏感程度的方法.它在电力系统分析与控制中得到了广泛的应用.从时间的角度将灵敏度方法分为静态灵敏度和轨迹灵敏度两类,并在应用中根据考察变量的不同,分别进行了评述.通过综观灵敏度方法在电力系统中应用,展示了灵敏度方法具有重要的研究价值,同时,也指出了当前灵敏度研究中尚存不足:缺乏统一的理论基础;在面对实际问题时,约束限制条件未能考虑,造成灵敏度缺乏可信性;灵敏度计算速度亟待提高等.     

灵敏度方法在电力系统分析与控制中的应用综述

灵敏度是利用系统中某些物理量的微分关系,来获得因变量对自变量敏感程度的方法。它在电力系统分析与控制中得到了广泛的应用。从时间的角度将灵敏度方法分为静态灵敏度和轨迹灵敏度两类,并在应用中根据考察变量的不同,分别进行了评述。通过综观灵敏度方法在电力系统中应用,展示了灵敏度方法具有重要的研究价值,同时,也指出了当前灵敏度研究中尚存不足:缺乏统一的理论基础;在面对实际问题时,约束限制条件未能考虑,造成灵敏度缺乏可信性;灵敏度计算速度亟待提高等。     

对电力财务报表分析体系及分析方法的若干思考

结合电力企业体制改革的现状,论述了不同财务分析主体的财务分析目的、现行主要的财务报表分析体系及其分析方法,提出了财务报表分析体系需要引起重视的几个问题.     

电网企业建筑节电方法及其潜力分析

对电网企业建筑电耗现状进行调研。详细分析电网企业建筑的主要类型及能耗分项计量情况,对在建筑电耗中占比最大的照明设备、空调系统建立节电潜力评估模型,从节能设备和管理手段2个方面有针对性地提出节电改造建议,并以某大型供电局办公大楼、某通信大楼和某220kV变电站等3个建筑为例进行深入分析,展示节电改造效果,最后对南方电网整体建筑节电潜力进行了概算。     

Stable region for autoparametric resonance in longitudinal power systems

In longitudinal power systems, there is the possibility that a low‐frequency oscillation mode may become unstable because of autoparametric resonance. The resonance occurs through interaction between two oscillation modes. In this paper, we calculate the stable region for the resonance by considering the interaction of the modes. First, we calculate steady‐state solutions by the harmonic balance method. The steady‐state solutions are stable or unstable. If we decrease the amplitude of one mode in an unstable solution, the modes decay. Conversely, if we increase the amplitude, the modes diverge. Namely, the unstable solution is located on the boundary of the stable solution. The amplitudes of the modes are rarely the same as those of the steady‐state solution. However, the amplitudes approach a steady state after some transients. If the steady state is in the stable region, the system is stable. If it is in the unstable region, it diverges. Lastly, we estimate the amount of damping torques necessary to stabilize the system with the newly calculated stable region. We have obtained results similar to those derived from the Mathieu diagram, for example, a certain amount of damping torques can stabilize the system irrespective of its size. AVRs can substantially reduce the amount of damping torques and other quantities. © 2000 Scripta Technica, Electr Eng Jpn, 132(2): 29–38, 2000     

邻接矩阵染色法及其在电力系统网络拓扑分析中的应用

电力系统的网络拓扑结构可以看作一个无向图,图的存储方式有两种,即邻接链表和邻接矩阵.提出了一种基于邻接矩阵的判断图的连通性的实用方法--邻接矩阵染色法,并将该算法应用到电力系统中进行网络拓扑分析,算例证明该方法计算过程直观、快速、有效.     

邻接矩阵染色法及其在电力系统网络拓扑分析中的应用

电力系统的网络拓扑结构可以看作一个无向图,图的存储方式有两种,即邻接链表和邻接矩阵。提出了一种基于邻接矩阵的判断图的连通性的实用方法——邻接矩阵染色法,并将该算法应用到电力系统中进行网络拓扑分析,算例证明该方法计算过程直观、快速、有效。     

网格技术及其在电力系统中的应用

介绍网格技术的产生、网格的基本概念，基本功能和性能等：结合我国电力系统发展的实际需要．展望网格技术在电力系统的可能应用．预测满足互联电网监控的电力网格所必须具备的一些基本特征。     

Stability analysis of power systems described with detailed models by automatic method

The power system stability analysis is approached taking into explicit account the dynamic performance of generators internal voltages and control devices. The proposed method is not a direct method in the usual sense since conclusion for stability or instability is not exclusively based on energy function considerations but it is automatic since the conclusion is achieved without an analyst intervention. The stability test accounts for the nonconservative nature of the system with control devices such as the automatic voltage regulator (AVR) and automatic generation control (AGC) in contrast with the well-known direct methods. An energy function is derived for the system with machines forth-order model, AVR and AGC and it is used to start the analysis procedure and to point out criticalities. The conclusive analysis itself is made by means of a method based on the definition of a region surrounding the equilibrium point where the system net torque is equilibrium restorative. This region is named positive synchronization region (PSR). Since the definition of the PSR boundaries have no dependence on modelling approximation, the PSR test conduces to reliable results.     

A method for analysis of back-swing phenomena of synchronous machine in multimachine power systems

This paper describes a new approach to the analysis of the back-swing phenomena in multimachine power systems. When a short-circuit fault occurs in a power system, some generators decelerate in a short period immediately after the fault in some cases. The phenomenon called back swing is caused by the transient responses in armature winding of synchronous machines and in transmission lines. To represent the back swing in detail by a mathematical model, these transient behaviors have to be described by sets of differential equations. Then not only does the order of differential equations increase, but the convenient expression of the transmission system by a set of node equations becomes useless. In this paper an equivalent power system model for the simple representation of the back swing has been proposed. First, an impedance for each machine that represents the transient of transmission system has been introduced. It is assembled into the differential equations associated with armature winding response. Then the transmission system is represented by a constant impedance matrix. This model makes it possible to calculate the transient behavior of armature flux in multimachine power systems. The transient torque brought to the rotor shaft by the flux is calculated directly and it represents the back-swing phenomena effectively.     

电力系统MDM设计分析

以电力系统MDM为背景,研究设计需求、设计原则等问题,为电力系统MDM的研发提供依据。     

Classification and analysis of voltage stabilities in power systems

The voltage stability problem has long been studied by many researchers mainly by means of two approaches: the static approach in which voltage stability is considered as a load-flow problem; and the dynamic approach in which it is dealt with as a stability problem in dynamic systems. However, up to now, these separate approaches have not clarified sufficiently the overall aspect of the voltage problem. In fact, there are no proper criteria to determine which approach is suited to analyze voltage stability. Thus, a basic study seems to be needed under such a situation. This paper investigates the voltage stability problem from the viewpoint of mechanism causing voltage instability. Various dynamic factors which affect voltages are studied as much as possible. First, possible voltage instability patterns are classified based on singular perturbation theory. That is, four categories of instabilities are defined mathematically. Second, a method of stability assessment for each instability is presented. It is clarified that the determinant of the load-flow Jacobian is an effective index to approximately assess two types of instabilities. On the other hand, the remaining instabilities require eigenvalue analyses or direct nonlinear analyses. The validity of these results is verified through numerical simulations and eigenvalue analyses in which dynamic characteristics of generating units, loads and tap-changing transformers are taken into account.     

A practical method for simplifying the dynamic stability analysis of interconnected power systems

In this paper a practical method for simplifying the analysis of large interconnected power systems is described. The approach is based upon a decomposition scheme which directly exploits the system structure. By analysing and quantifying the strength of connection among generating units, a large power system is decomposed into weakly connected subsystems, each consisting of a group of tightly coupled machines, a common situation in practice. Then the overall system stability is established from the analysis of each decoupled individual subsystem.The method, which can be carried out systematically, saves a considerable amount of storage space and computation time and provides sufficiently accurate results. The procedure is illustrated using a five-machine fifteen-bus system.