Research On Communication Channel Of HVDC Transmission System

HVDC transmission system is capable of delivering high power for a long distance withless energy loss in a flexible way. Developing HVDC complies with the nation’s resourcestrategy and it is considered to optimize the allocation of resources, and to achieve balancedand sustainable development. Insufficient technically contract of power and communicationoperators is a probem for a long time, and the safe and stable operation of DC system isdirectly affected by inter-station communication channel reliability. Therefore, it is significantfor maintenance and communication operation to research HVDC system control principle ofprotection function, analyzes relevant communication channel configuration, and interrupteffects of DC power transmission.In this paper, the demand of HVDC inter-station communication is analyzed with therelated communication equipments. DC pole control, station control on the system areanalyzed, and the composition, principle, function of the dc protection, the internal LANnetwork, inter-station WAN network composition and DC control protection information flowin communication backbone is analyzed as well. Then an evaluation model is established forthe interruption analysis of HVDC inter-station communication channel. The influences onthe pole control system, station control system and operation monitoring system are evaluatedrespectively, in the case of the inter-station communication interruption. The influence of thefault impact analysis program is put forward, in Zhaoqing converter station as an example,with the interrupt experiment evaluation. It is concluded that the HVDC pole is not blocking,but will lead to differential protection87DCLL block, in case the channel interrupts.According to the HVDC stations in Guangdong, communication device, operation mode,and communication rate are analyzed, for Gaozhao, Xingan, Tianguang, and Chusui, the fourHVDC transmission system. Then the topology information of channel is assessed, concludedthat four DC transmissions can meet the requirements of redundancy and reliability.Finally, in view of the runtime electromagnetic interference produced by rectifier(inverter) station, the communication equipment anti-interference test is designed, and withthe Gaozhao HVDC as experimental object. The magnetic field strength and the signal currentfrequency characteristics are measured, before and after the DC system stopped. Then theelectrostatic defense is tested. Test results show that the Gaozhao HVDC equipments can meetthe national standard of the equipment interference, will not lead to the communication error.This paper can provide reference for the DC transmission system operation and maintenancepersonnel， maintenance of communication channel and troubleshooting guide DC system.