考虑直流附加控制能力的近端地方电网与直流外送系统的接入模式选择

针对能源基地近端、规模小、网架结构弱的地方电网的并网需求,提出考虑直流附加控制能力的近端地方电网与直流外送系统的接入模式选择方法。首先,在总结联网和孤岛接入模式存在问题的基础上,分析直流紧急功率控制和直流附加频率控制对送端系统稳定的影响,明确了直流附加控制能力对小容量地方电网接入模式选择的显著作用。进一步地,给出了模式选择原则,借鉴电力系统安全稳定导则等的相关规定,计及潮流、短路电流的要求,综合考虑故障发生几率及其对送端系统稳定影响的严重程度,确定第一级、第二级暂态安全稳定校验顺序和标准,根据交、直流特征量反映系统稳定的敏感程度,给出暂稳校验判据。最后,以某实际直流工程为算例,验证了模式选择方法的有效性与适应性。

Connection Mode Selection of Near-end Local Power Grid and HVDC Transmission System Considering DC Additional Control Capability

To meeting the grid-connecting demand of the local power grid with small scale and weak grid structure,a connection mode selection method of near-end local power grid and HVDC transmission system is proposed considering DC additional control capability. First of all, on the basis of summarizing the problems of gird-connected and isolated-connected modes, the influence of DC emergency power control and DC additional frequency control on the stability of the sending system is analyzed, and the DC additional control capability has a great effect on selecting the connection mode of small-capacity local power grid. Furthermore, the principle of mode selection is given, and the relevant rules of safety and stability of power system are given. Taking into account the requirements of power flow and short circuit current, the first and the second level of transient safety and stability check sequence and standard are proposed by comprehensively considering the failure probability and its influence on the stability of power system. In addition, according to the characteristic quantity of AC and DC systems that reflect the degree of sensitivity to stability, the transient stability criterion is given. In the end, a practical HVDC project is taken as an example to verify the validity and adaptability of the mode selection method.