Development and application of distribution network comprehensive analysis system
Through a system study of the fundamental theories of distribution network analysis, operation optimization and network architecture assessment, including static security analysis theory, power flow calculation method, state estimation technique, network optimization method, fault isolation and recovery algorithm, and reactive power optimization algorithm, etc, a graphic distribution network analysis system was developed. Feeder renovation and sectionalization is determined by using the “User Loss Vs Load Loss” charts with both economy and reliability taken into consideration. Interpolation method is used to work out an optimal reactive power compensation capacity, enhancing computational speed. Vector data layering and blocking technique increases the processing speed of the graphic system. The system has been applied in over ten power utilities, and proved effective and helpful.
Research on the structure of urban power network based on long-term planning of EHV network
In the procedure of urban electric network planning, many problems should be considered, such as how to adapt to the future load growth in the city, how to ensure coordinational development with future planning of higher voltage network, how to keep the N-1 structure of the lower voltage network as possible in the process of breaking up electromagnetic ring, and how to avoid the waste of huge investments due to breaking up electromagnetic ring and so on. The paper proposed the guiding ideology of planning urban electric network structure and corresponding technical principle: during the development of urban power network, the prospective planning of the higher voltage network should be considered and the timing and location to break up the electromagnetic ring should be reasonably determined; after breaking up the electromagnetic ring, the target network structure should keep the small ring structure as much as possible instead of the radial structure with power supply by single circuit. The guiding ideology of urban electric network planning and corresponding technical principle proposed in the paper were validated by a real case.
Research on Operating Modes of 750 kV Northwest China Power Grid Electro-Magnetically Coupled with 330 kV Power Grid
Along with the completion and put into service of 750 kV Northwest China power grid, the original 330 kV network will electro-magnetically coupled with the newly built 750 kV power grid. The authors research the influence of operation modes of electro-magnetically coupled 750/330 kV power grid on system security and stability when Northwest China 750 kV main network is preliminarily completed at the end of 2008. The results of static security and stability analysis show that before a strong 750 kV network is built up, the operation mode of electro-magnetically coupled power grid, i.e., the close-loop operation mode, is available to enhance the transmission capacity and stability level of Northwest China power grid than open loop operation mode. For the potential problems such as system oscillation and restricted power transmission that may occur under close-loop operation, some suggestions are put forward, including reinforcing the configuration of security and stability control devices, developing circuit breakers with higher interrupting capacity, optimizing operating modes and network structure, etc., to ensure stable operation of Northwest China power grid.