考虑运行损耗和功率裕度的VSC-MTDC系统改进优化下垂控制策略  

Improved Optimization Droop Control Strategy Taking into Account the Network Loss and Available Headroom for VSC-MTDC System

作　　者：曾琦[1] 李兴源[1] 张立奎[2] 

机构地区：[1]四川大学电气信息学院,成都610065 [2]国网江西省电力公司九江供电分公司,九江332000

出　　处：《高电压技术》2016年第10期3117-3125,共9页High Voltage Engineering

基　　金：国家重点基础研究发展计划(973计划)(2013CB228200);国家自然科学基金(51037003)~~

摘　　要：不当的直流电压下垂系数易造成多端柔性直流输电(VSC-MTDC)系统运行损耗增加或部分换流站满载,为此提出了1种考虑网络损耗和功率裕度的改进优化下垂控制策略。分析了影响直流网络潮流的因素,在考虑直流线路电压降的情况下,推导出了换流站间功率分配与下垂系数的关系式。提出了直流网络潮流优化计算方法,并得出了各换流站最优下垂系数。以换流站优化下垂特性为基础,设置直流电压拐点,综合考虑直流系统运行损耗和换流站功率裕度,提出了改进的优化下垂控制策略。在PSCAD/EMTDC仿真软件中搭建6端柔性直流输电系统仿真模型,对3种下垂控制策略下系统的运行特性进行了仿真分析,结果表明:常规下垂控制按换流站额定容量分配功率,优化下垂控制考虑直流网络损耗,改进优化下垂控制兼顾系统运行损耗和换流站设备使用率。仿真结果与理论分析一致,验证了所提改进控制策略的有效性和可行性。Inappropriate DC voltage droop coefficient will lead to the losses increase and partial converter station overload of the multi-terminal flexible HVDC（VSC-MTDC） system, in order to solve this defect, taking network loss and available headroom of converter station into account,we proposed an improved optimization droop control strategy. Factors affecting power flow of the network are analyzed,and the relationship of power distribution and droop coefficient is derived by taking the DC line voltage drop into account. The method of power flow optimization of the current network is proposed and optimal voltage droop coefficients of each converter station are calculated. By setting up the DC voltage inflection point and taking into account running losses of current system and power margin of converter station based on optimal droop coefficients, the improved optimization droop control strategy was put forward. The operational characteristic under three control strategies were simulated and analyzed by establishing a simulation model of the six-terminal flexible DC transmission system in PSCAD/EMTDC. The simulation results demonstrate that power distribution is proportional to rated capacity of converter station in conventional droop control, DC network loss is considered in optimization droop control, running losses of current system and capacity utilization are considered in improved droop control. The expected performance of theoretical analysis validates the effectiveness and feasibility of the proposed method.

关 键 词：直流电压下垂控制 功率分配 潮流优化 线路损耗 功率裕度 

分 类 号：TM721.1[电气工程—电力系统及自动化]