MGP提高直流送端新能源动态无功补偿能力研究

高压直流输电线路送端常伴随一定比例的新能源电源接入,新能源占比过高会导致电网动态无功补偿能力不足,并降低送端系统电压调节能力和直流线路有功功率传输稳定性。同步电机对系统(motor-generator pair,MGP)具备动态无功补偿能力,能较好满足新能源电场与直流输电线路送端暂态无功需求。本文根据MGP的系统结构和数学模型,分析了MGP提供动态无功补偿的响应过程,得出适当减小Xd″、Xd′、Td0′与励磁调节器励磁增益倍数可以增强MGP无功输出能力的结论。对比了交流系统不同程度电压降落下MGP的动态无功响应能力;在此基础上,还研究了改善MGP系统结构参数后其无功补偿能力的提升表现。仿真结果表明:交流系统电压跌落幅值越大,MGP的动态无功补偿能力越强,更有利于维持直流线路功率传输稳定;改善MGP系统参数后,其动态无功响应能力得以进一步增强。

Study on Improving the Dynamic Reactive Power Compensation Ability of Renewable Energy on DC Transmisson Sending System via Motor-generator Pair (MGP)

The sending end of HVDC transmission line is often accompanied by a certain penetration of renewable energy power access.If the penetration of renewable energy is too high,the dynamic reactive power compensation capacity of the power grid will be insufficient.This problem would reduce the voltage regulation capability and the power transmission stability of the sending end system.Motor-generator pair(MGP)has dynamic reactive power compensation capability,which can better meet the transient reactive power demand of the renewable energy electric field and the transmission end of the DC transmission line.Based on the system structure and mathematical model of MGP,this paper analyzes the response process of MGP to provide dynamic reactive power compensation,and concludes that properly reducing Xd″,Xd′,Td0′and the excitation regulator's excitation gain coefficient can enhance the reactive output capability of MGP.We compare the dynamic reactive power response capability of MGP under different voltage drops of AC system,and then study the improvement performance of the reactive power compensation ability after improving the structural parameters of MGP on this biasis.The simulation results show that the greater the voltage drop amplitude of the AC system,the stronger the MGP dynamic reactive power compensation capability,which is conducive to maintaining the stability of DC line power transmission.After the MGP system parameters are improved,the dynamic reactive power response capability can be further enhanced.