同塔双回直流输电系统接地极电流控制策略

直流接地极入地电流将造成变压器直流偏磁、埋地金属设施腐蚀等问题。为抑制接地极电流带来的不良影响,已有研究主要集中于在设备侧增加保护措施以及使用分布式接地极技术等方向,尚未有从源头对接地极电流进行控制的策略。因此,文中结合同塔双回直流输电系统控制保护特性,提出了2种控制策略。一是在接地极电流限制功能的基础上,通过梳理该功能现有控制逻辑,揭示应用该功能时存在的缺陷和隐患,并通过仿真进行一一验证,在此基础上,进一步提出控制逻辑的优化方法;二是在直流控制保护系统中新增回内联跳相关功能,实现一极非正常闭锁联跳本回另一极。最后,利用实时数字仿真(RTDS)平台对2种控制策略进行仿真测试,验证了控制策略的有效性。

Control Strategy of Grounding Electrode Current for Double-circuit HVDC Transmission Lines on the Same Tower

The grounding electrode current could cause many problems, such as DC bias of transformers, erosion of metal facilities underground, and so on. To restrain the bad effects of grounding current, the existing studies mainly focus on the technologies, such as increasing protection measures on the side of equipment, as well as the use of distributed DC grounding electrodes. So far, there is no control strategy of the grounding current at the source has been put forward. Therefore, this paper proposes two control strategies of the grounding current combining with the control and protection properties of double-circuit high voltage direct current(HVDC)transmission lines on the same tower. The first one is to reveal the defects when applying the function by checking the control logic of the existing grounding current limitation function and verify those defects one by one. On this basis, the optimization method of control logic is further put forward. The second one is to add a new bipolar shunt trip-ping function in one circuit in the HVDC control system. The function blocks one pole immediately after another pole is protectively blocked. Finally, these two kinds of control strategies are both tested by real-time digital simulation(RTDS)platform, and the results validate the correctness and effectiveness of the control strategies.