超高压电磁环网的特点与案例分析

针对仍普遍存在的超、特高压电磁环网,结合省级电网的实例总结了电磁环网的不同发展形态和结构,认为电磁环网的主要风险在于潮流转移和控制,并提出了衡量电磁环网强弱和风险的耦合度指标。在网络结构优化和加强方面,认为强耦合的弱电磁环应优先加强上级电网,弱耦合的强电磁环应优先考虑短路控制和简化结构,多级电磁环应尽快解耦等,分析了电磁环网的典型分片方案。鉴于超、特高压电磁环网将长期存在,阐述了电磁环网单一和连锁跳闸后实用化的潮流转移控制方法,特别是针对大功率、强耦合型电磁环网提出了一种严重故障后快速切除联络元件的非常规稳定控制措施,以实现解耦控制、均衡潮流,有效提升过渡期电网的稳定水平和输电能力。在实际电网中的多个应用实例表明其效果良好。

Characteristics and Case Analysis of Extra-high Voltage Electromagnetic Loop Networks

In view of the still existing extra-high voltage(EHV)and ultra-high voltage(UHV)electromagnetic loop networks, the different forms and structures of development of electromagnetic loop networks are summed up with the cases and examples in a provincial power grid. It is believed that the main risk of electromagnetic loop networks lies in the transfer and control of power flow. The degree of coupling is proposed as an index to measure the intensity and risk of electromagnetic loop networks. In terms of network structure optimization and strengthening, it is considered that the higher voltage power system should be strengthened prior to the strongly coupled weak electromagnetic loop, and the short circuit level control and structure simplifying are more important for the weakly coupled strong electromagnetic loop while multilevel electromagnetic loops should be decoupled as soon as possible. Then the typical split schemes of electromagnetic loop networks are analyzed. Since EHV and UHV electromagnetic loop networks will exist for a long period of time, practical power flow transfer control algorithms for single element trip and cascading trip of electromagnetic loop networks are elaborated. Especially, a kind of unconventional stability control measure of the fast tie-element removal strategy after serious fault is put forward to decouple electromagnetic loops and balance power flow for high-power and strong-coupling electromagnetic loop networks. The stability level and transmission ability of the electromagnetic loops are effectively enhanced. The research results have been applied in actual power grids with good effect.