【作者】 薛振宇；

【导师】 房大中；

【作者基本信息】 天津大学 ， 电力系统及其自动化， 2011， 博士

【摘要】 随着西电东送和全国联网工程的实施,已建和在建直流输电系统不断增多,大规模交直流混联电力系统已经成为我国电网输电的基本格局。交直流混联系统所呈现的稳定性特性十分越复杂,迫切需要一套快速有效的数学工具用于研究和分析混联电力系统的稳定特性及其控制方法。本论文根据直流输电系统的数学模型及其与交流系统的耦合关系,从交流和直流系统的接口技术入手,探索了交直流混联电力系统数字计算的新方法,取得的主要成果如下:对现有的交直流混联电力系统潮流计算方案提出改进,将直流输电系统数学方程变换为一组具有明确概念的约束方程,在保证收敛精度和收敛速度的前提下,简化了程序设计。并根据互联电力系统的联网特性,将交流和直流联络线进行分割,得到一个不连通的根结点和若干个由区域电网组成的叶结点,实现互联电力系统分区潮流计算。设计了一套可用于大规模交直流混联电力系统静态电压稳定分析的实用化预测校正连续潮流算法。在交流系统连续潮流计算中,通过直流系统的约束方程改进预测环节和校正环节,并提出直流系统控制方式随交流电压变化的逻辑转换策略和实现方法,将直流输电系统嵌入到连续潮流算法中。在南方电网的方式数据上验证了该算法的效果和效率。发展了交直流混联电力系统机电暂态仿真方法,将交流系统仿真算法扩展为可计及直流输电系统调节器、VDCOL环节、功率调制、闭锁与重启动等复杂控制功能的仿真算法。在华中华东测试系统的方式数据上取得满意的效果。尝试采用时域仿真技术优化直流输电系统调节器参数,并提出一种新的目标函数,旨在抑制交流系统和直流系统受扰后的振荡。通过轨迹灵敏度方法,获得系统动态性能指标相对于直流系统调节器参数的梯度信息,求得更新调节器参数向量的搜索方向,找到改善系统功角稳定性参数配置方案。在四机双区域测试系统验证其效果。更多还原

【Abstract】 With the countrywide interconnection and power transmission from West to East, more and more HVDC systems have been established during the several years. The fundamental framework of Chinese national power grid has been developed into a large-scale multi-area ultra-high-voltage AC/DC hybrid power system, as a result the characteristics of the system stability become more and more complicated. It is necessary and desirable to enhance the mathematical tools for researching the stability and analyzing the control method of the power system. On the Basis of the HVDC model and the relationship between the AC and DC systems, new digital computation techonolgy therefore is studied as follows:The current load flow method used for AC/DC hybrid power system is improved with the currents of convector transformer. Thus the restrict equations of the DC system is derived, which is used to form a novel bi-directional iteration approach. Meanwhile, a network division method, named two-level tree model, is developed to partition the AC/DC systems into one root-node and several leaf-nodes with AC/DC tie-lines buses. The method is easy to implement, and its convergence precision and speed is preserved well.A novel continuation power flow method for static voltage stability analysis of large-scale AC/DC hybrid power system is designed. With the restrict equations of the DC system, the predictor and the corrector of the continuous power flow method are improved as well as the switch strategy of the HVDC system is proposed while the AC voltage fluctuation. The effectiveness and efficiency of this method is proved on the South China AC/DC power grid system.The electromechanical transient simulation arithmetic of the AC system is further extended to apply to AC/DC system which could consider the complex control model of HVDC, such as HVDC regulator, VDCOL, modulation controller, bipolar block logic and auto-restart function. Promising effect is suggested by the case studies on Central-China East-China test power system.A scheme using time domain simulation to optimize HVDC regulator parameters is carried out with a new objective function to enhance the stability of both the AC system and the DC system. Trajectory sensitivity method is utilized to compute the gradient vector of the dynamic performance index of the power system with respect to the HVDC regulator parameters to be tuned. Furthermore, the search direction for updating the HVDC regulator parameters is given, and new HVDC regulator parameter configuration could be found for better angle stability. The result is tested on the 4-machine 2-area test power system.更多还原