优化潮流转移特性的直流电网网架结构设计

DC Grid Structure Design with Optimized Power Flow Transfer Characteristics

为了研究直流电网网架的变化对潮流转移的影响,探究如何设计出潮流转移特性更佳的直流网架,通过直流分布系数快速计算线路断开时其他线路的潮流增量和负载率,采用潮流分布熵衡量线路断开后的直流电网潮流负载率分布情况,采用潮流转移熵反映目标线路受网架内其他线路断开的潮流转移影响,提出网架结构特征值反映网架内直流线路性质。在PSCAD/EMTDC软件上搭建±400 kV五端双极线路直流系统,仿真验证结果表明,网架的结构特征值越大,其潮流分布熵越小;连接电源与负荷的线路的潮流转移熵普遍较高;增加连接电源与负荷的线路后,直流线路的潮流转移熵有不同程度的降低。可见,在进行直流电网网架结构设计时,优先考虑架设连接电源与负荷的直流线路,能够有效地降低直流网架的潮流分布熵和直流线路的潮流转移熵,使直流网架的潮流转移特性更佳。

In order to study the influence of DC power grid structure changes on power flow transfer and explore how to design a DC grid with better power transfer characteristics,the DC distribution coefficient is used to quickly calculate the power flow increment and load rate of the other lines when one line is disconnected.Power distribution entropy is used to measure the distribution of load rate of the DC grid.Power transfer entropy is used to reflect the influence of power flow transfer of the other lines in the grid.The structural eigenvalue is used to measure the DC line characteristics.A±400 kV five-terminal MMC-MTDC system is established in PSCAD/EMTDC,and simulation results show that power distribution entropy of the grid decreases with the increase of the structural eigenvalue;The power transfer entropy of the line connecting to the power supply and the load is relatively high.After adding a line connecting to the power supply and the load,the power transfer entropy of the DC line in the grid generally has different degrees of reduction.It is concluded that in the design of the DC grid structure,priority is given to erecting the DC line connecting the power supply with the load,that can effectively reduce the power distribution entropy of the DC grid and the power transfer entropy of the DC line.So that the DC grid has better power flow transfer characteristics.