电力系统的多次大停电事故均伴随着暂态失稳现象。能量函数法作为研究暂态稳定问题的主要方法，不仅具有快速定量评价系统稳定性的实用功能，并且在指导控制策略设计和认识稳定机理方面具有不可替代的理论价值。能量函数法的主要难点是如何克服模型复杂性的限制，该问题在大规模新能源接入和特高压互联电网发展过程中变得尤为突出。针对该问题，本文开展了以下三个方面的研究： （1）结合PEBS法和BCU法，提出了基于端口能量的新能源电力系统暂态稳定能量函数法。证明了采用端口能量的系统总能量是系统的能量函数；证明了端口能量的能量聚集效应；阐述了端口能量与广义势能的联系与区别；分析了采用端口能量计算对象系统的暂态能量，给暂态稳定评估带来误差的原因。结合IPEBS法，提出了基于端口能量的含风电电力系统暂态稳定评估方法。算例验证了有效性。深入分析了BCU方法对含光伏发电的复杂电力系统模型的适用机理，从而将结合端口能量的BCU方法应用于含光伏发电的电力系统暂态稳定性评估。算例验证了有效性。相关偏微分能量函数构造方法不能在BCU方法中计及光伏发电的动态，提出了改进的偏微分能量函数构造方法，改进后可以计及新元件的动态。 （2）提出了基于实部端口能量的附加阻尼控制策略（R-SDC）和进一步的综合附加阻尼控制策略（C-SDC）。与现有基于虚部端口能量的附加阻尼控制策略（I-SDC）相比，R-SDC更适用于电阻主导的电网，C-SDC可以综合考虑有功无功功率对电压和相角的耦合控制作用，因此在电阻和电抗主导的电网中均优于I-SDC。将基于端口能量的附加阻尼控制策略应用于含光伏发电的电力系统，仿真验证了有效性。 （3）针对华北华中特高压联网过程中出现的特殊扰动冲击现象，推导了一般形式的适用于大干扰的模式激发程度计算公式，结合支路势能法，给出了区域互联电网的扰动冲击机理。 总之，本文发展了基于外特性的能量函数构造和暂态稳定分析与控制方法，一定程度上克服了能量函数法的模型复杂性限制，对解决大规模新能源接入和特高压互联电网发展过程中遇到的暂态稳定分析与控制问提具有指导价值。
Major blackout events happened with the transient unstable phenomenon. Energy function method, which is one of the fundamental transient stability analysis methods, not only has the practical function of assessing the system stability fast and quantitatively, but also has the irreplaceable theoretical value of providing theoretical guidance of control strategy design and undetandering the stability mechanism. One main difficulty of the energy function method is how to overcome the limitation of modeling complexity. The problem becomes particularly prominent with the development of large scale renewable generation integration and interconnection of regional grids. For the proplem, the following three aspects are inverstigated: (1) With PEBS and BCU method, the energy function method of power systems with renewable generation is proposed based on port energy. It is proved that the total energy is an energy function with part of the transient energy calculated by port energy. The energy aggregation effect of port energy is also proved. The connections and differences between port energy and general potential energy are investigated. The reasons led to the error in transient stability assessment are also analyzed when port energy is used. Based on port energy and IPEBS method, a transient stability assessment method is proposed for power systems with wind generators. The effectiveness is validated by case studies. The adaptive mechanism of the BCU method for complex power systems with SPVGs is analyzed throughly. And therefore the BCU method with port energy is applied to the transient stability assessment of power systems with SPVGs. The effectiveness is validated by case studies. The relative energy function construction method by solving PDEs can not contain the state variables of the SPVGs in the BCU method. The modified PDE method is proposed to overcome this drawback. (2) The supplementary damping control (SDC) based on the real part of port energy (R-SDC) and the further comprehensive SDC (C-SDC) are proposed. Compared with the existing SDC based on the imaginary part of port energy (I-SDC), the R-SDC is more suitable for resistance dominated networks. The C-SDC can consider the coupling feature between the active/reactive power and the voltage magnitude/angle, and therefore is better than the I-SDC in both resistance and reactance dominated networks. By applying the control strategies to the solar photo voltaic generators in modified IEEE benchmark systems, the effectiveness of the proposed control strategies is validated. (3) For the special stability phenomenon in the North China-Central China interconnected power system, the mode excitation degree calculation formula of general power system models for large distances is derived, and with the branch potential energy method, the disturbance impact mechanism of regional interconnected systems is provided. In sum, the energy function construction and transient stability analysis and control methods based on the external characteristics are developed, which partly overcome the limitation of modeling complexity in the energy function method. These works have instruction value for solving the transient stability analysis and control problems in the development of power systems with large scale renewable generation integration and interconnection of regional grids.
