Studies On The Core Technologies Of Smart Operations And Controls In Ultra Large City’s Grid

As the power system growing rapidly and the relationship between sub-networks in different voltage levels becoming more closely, the operating characteristics of power system become more complicated. At the same time, the customers’ demand of power supply reliability, security and quality is improving significantly. The traditional protection & control technologies can’t fully meet the new requirements of the integrated operation and intelligent dispatch in the smart, reliable, environmental and efficient power system. With consideration of the operating problems in the large city, the key protection & control technologies for smart grid are researched in this thesis. And the research results have been applied in Guangzhou power grid, which is a typical load center with multiple HVDC feed-in and contains a large number of 500kV~380V power equipments. The key technologies involve power system emergency control and operation control, and the related work is composed as follows.(a) The two-plane & multi-level structure of power grid operation smart system is proposed. According to the different control objectives and response time scales, the operation system can be divided into two planes, emergency control plane and dispatching & monitoring plane. The multi-level structure of the power grid operation system is aiming to the different concerns in different network levels, including substation level, regional-area level and wide-area level. The protection & control system is divided into different levels according to the functions and data flows. Through the interaction between emergency control plane and dispatching & monitoring plane, a more coordinate and optimized security defense system can be constructed.(b) In emergency control plane, the the regional protection & control technologies are presented based on the multi-level protection & control structure. Firstly, a novel protection & control approach and scheme based oon the regional information are proposed. The approach applied the regional information to optimize the performance of protection devices, which can realize the the integration and coordination of regional protections. Secondly, the strategies of the fuction set up and cooperation are proposed, which can realize the integration of the power relay and fafety automatic control devices. Thirdly, the transmission linesrelay protection principle based on message blocking and regional standby source automatic switch principle based on regional network information are proposed. Finnaly, the research results have been applied in the 110 kV Licheng power grid in Guangzhou, which the first application project of regional protection & control system in our country.(c) In the dispatching & monitoring plane, the optimal allocation of dynamic reactive power and the coordinated voltage control technology of receiving-end urban power grid considering the dynamic reactive power is presented. Firstly, a optimal collocation method of dynamic reactive power is proposed by the voltage recovery comprehensive index, which can analyze the effect of dynamic reactive power compensation on dynamic voltage support after failure. Secondly, a coordinated voltage control strategies in the substations considering the dynamic reactive power compensation and traditional reactive power compensation are proposed. Finally, the entire network reactive power/voltage control system, which coordinates the transmission and distribution network, with multi-objective, multi-level, discrete and continuous coordination control is established.(d) In the cooperation between the two planes, the cross-plane coordinating control technologies based on the on-line control are researched. Firstlty, the schemes for setting-group on-line control including setting values and selecting active setting-group, on-line controlvirtual isolator and on-line resetdevice is proposed. The setting group control model is desinged with IEC60870-5-103 which is the newest technology in the country. Secondly, the strategies and overview operation information model of the cross-plane coordinating control and decision is proposed based on the protection & control devices on-line control. Thirdly, the Automatical Battery-Auto-Transfer-Switch Control(ABC) approach is researched based on the the cross-plane coordinating control. The Battery-Auto-Transfer-Switch operation strategy is calculated basing on the overview operation information in EMS, and the strategy is excused to the ABC devices through on-line control technology.The research results of the thesis have been applied in the Guangzhou power grid and achieved the approval of the authorities in the country. The technologies researched can improve the central city power grid’s operating efficiency and integrating level. The research and application experience is a great reference to improve power grid operational performance too.