对后验仿真准确度的研究是电力系统仿真可信度研究的重要组成部分，但当仿真与实测有差异时，如何进行仿真验证工作成为一个难题。根据广域测量系统(WAMS)能够提供独立于模型和参数的动态过程同步数据的特点，提出了基于WAMS的电力系统分层分块的动态仿真验证策略。分层策略利用电网由不同电压等级所组成的特点将电网分层，在不同层次上进行仿真验证;分块策略则是利用电网结构按照元件和区域的思想将系统进行解耦来实现仿真验证。通过上述策略，将WAMS量测值作为电网数值仿真的动态等值输入，实现了仿真的解耦，缩小了定位引起仿真误差元件的区间。结合电力系统仿真软件PSS/E给出了基于WAMS的分层分块仿真验证策略的工程实现途径。

电力系统稳定域边界的逼近一直是应用能量函数方法分析电力系统暂态稳定的难点。采用能量函数方法所应用的电力系统数学模型，基于半张量理论所给出的电力系统稳定域边界逼近算法，文中分别对单机对无穷大系统及IEEE3机9节点标准测试系统的稳定域边界进行逼近，并依据近似的稳定域边界估计了临界切除时间。通过对近似稳定域边界的可视化及与传统的等能量函数曲线稳定域边界的对比，充分显示近似稳定域边界提高了直接法分析电力系统暂态稳定的精度。进一步指出了应用半张量方法逼近电力系统稳定域边界仍需深入研究的问题。

电力系统稳定域边界的逼近一直是应用能量函数方法分析电力系统暂态稳定的难点。基于半张量理论，文中给出了逼近电力系统稳定域边界的矩阵方程。通过矩阵运算，可以获得电力系统稳定域边界的高阶逼近表达式。所提出的算法没有对系统进行任何形式的非线性变换，不需要求解系统所有的特征根与特征向量，也无需进行时域积分；算法充分保留了系统的非线性结构，形式简洁。由于该算法完全基于矩阵运算，因此非常适于计算机实现。

A load model is one of the most important elements in power system simulation and control. Recently, the constant impedance, constant current, and constant power load in combination with the induction motor load have been widely used as the composite load model, whose parameters are all identified from the field measurements in measurement-based load modeling practices so far. However, there is virtually no research conducted on whether all these parameters could really be identified. This paper investigates the possibility on reducing the number of composite load model parameters to be identified from field measurements. This paper first shows that direct application of the IEEE load motor parameters in the composite load model may be inadequate on describing the load dynamics over different operating status. Then the perturbation method is used to derive the trajectory sensitivities of the equivalent motor parameters, based on which the reduction on the identified parameters of the composite load model is presented. Two cases of measurement-based load modeling in North China and Northeast China are studied to illustrate the validity of the reduction method. It is shown that the reduction does not lose the model’s capability on describing the load dynamics. The reduction on the number of identified parameters not only provides a possible way to solve the multi-valued load model problem based on the current practices on measurement-based load modeling, but it also facilitates building of the load model with more components included in it. Meanwhile, reducing the identified parameters reduces the identification time; thus, the proposed strategy significantly enhances the efficiency of the load modeling work.

The energy function method developed so far assumes that the active load is constant. However, most of the actual load is voltage dependent, which hinders the application of the energy analysis method to the actual power system. On the other hand, the fast development of measurement techniques, especially the wide area measurement systems (WAMS) applied widely in worldwide power system nowadays, presses for the on-line transient stability analysis tools based on the system measurements. The voltage-dependent load into the energy analysis of power system transient stability is discussed. The effect of the comprehensive load characteristics on the system energy is discussed and a WAMS-based energy indicator on the system stability status is proposed. The indicator is easy to be calculated and thus real-time in the operation centre is monitored. The proposed method does not rely on any specific load model, and various load characteristics on different buses can be considered. Simulations on two test systems verify the effectiveness of the proposed method.