摘要
含有N个节点的直流电网中可控支路数遵循N–1准则,当支路数多于N–1时,会出现不可控支路,故引入直流潮流控制器实现与换流站的协调控制,最大限度地保证所有支路运行在载流限值内。然而,接入直流潮流控制器后,常规潮流计算将增加新的节点,从而导致系统节点导纳矩阵和雅克比矩阵阶数的增加、矩阵元素的变化等,给潮流计算带来附加计算量,影响潮流计算的速度和效率。以电压源型潮流控制器为例,推导含电压源型潮流控制器的直流电网潮流计算数学模型;将等效注入功率法引入含有潮流控制器的直流电网潮流计算中,新增节点以附加注入功率的形式转移到控制器安装支路的两端节点,避免了新节点引入的大量计算。最后,以改造后的某五端柔性直流工程为例,通过等效注入功率法和仿真软件在含有一个和多个控制器时的直流电网潮流计算结果的对比,验证该方法的有效性。
The number of controllable branches in a DC grid equals to the available nodes N in the gird minus one(N–1). It means that it's difficult even impossible to ensure certain branches not to be overloaded if the number of branches in the DC grid are far more than N–1. Therefore,the introduction of DC power flow controller can maximally guarantee that the power flows in all branches are within their ratings and realizes coordination control with converter station. However,the new nodes caused by conventional power flow calculation after the introduction of the controller may result in the increase of order number and change of element in the node admittance matrix and the Jacobin matrix,leading to additional calculated amount and then the impacts on the calculating speed and efficiency comparing to the conventional power flow calculation. The mathematical models for power flow calculations of DC grids with the voltage source type of DC power flow controller based on the series voltage source type of power-flow controller are derived. The method of equivalent power injection is introduced to the power flow calculations of DC grids with the power flow controller. The new nodes due to the installation of the power flow controller are transferred to both of the ending nodes of the branch within the controller in the form of additional injection power,preventing the large amount of calculations due to the additional new nodes being introduced. Finally,a DC grid based on a 5-terminal DC project is used to validate the rationality and effectiveness of the analysis method by comparing the power flow calculation results obtained from the equivalent power injection method and simulation software with one or more controllers installed in the DC grid.
出处
《智能电网》
2015年第3期208-213,共6页
Smart Grid
基金
国家自然科学基金(51377016
51477027
51307018)
吉林省科技发展计划项目(20130206038GX)~~
关键词
直流电网
直流潮流控制器
等效注入功率法
潮流计算
DC grid
DC power flow controller(DCPFC)
equivalent power injection method
power flow calculation
