Research And Application Of Station Domain Automatic Bus Transfer Protection In Substation

Currently, independent automatic devices are used in general substations. Such as the spare automatic switch device, the low cycle load shedding equipment, etc. The information of the switches and circuit breakers is transmitted by the signal cable, and the AC quantity is transmitted by the independent AC gathering circuits. The equipment distinguishes the power gird operation mode, and decides the action logic. Then the action logic is transmitted to the related switches and breakers by the output cables. In this achievement mode, lots of signal cables and AC gathering circuits need to be installed in the substation, which is much cost, and with complex wiring.The complex mode of wiring generates inconvenience and risk in the input/quit and maintenance of the equipment. When the substation is expanded or changing its operation mode, it’s needed to be modified on the main protection program unit, parts of the wiring cables require changing, which brings large quantity of work on the running and maintenance, and risk on the safe operation of the power grid, that can’t adapt to the flexible operation mode of the substation.For the above considerations, it is necessary to research and develop on a kind of spare automatic switch system of substation domain, which can provides functions as below: Automatic judging the operation mode of the substation; Correspondence establishing the action logic of the spare automatic switch device; Prevention on the over-loading of the main transformers; Achieving the overload shedding function; Coordinating the action logic of the spare automatic switch devices in different voltage levels, etc.It is studied on the theory of the spare automatic switch devices in a substation domain, which contains the analyses on the establishing the action logic of automatic judging the operation mode of the substation, blocking conditions, input/quit mechanism, and the manner in the overload shedding, etc. It is illustrated that how to implement the spare automatic switch system of substation domain in a certain substation, and the trying-running situation of the developed spare automatic switch system of substation domain in Zhongshan power grid. The spare automatic switch system of substation domain takes advantages as below:1. The function of the spare automatic switch in different voltage levels can be achieved in only one spare automatic switch system in a substation domain, which can avoid the shortage of poor information transfer, difficult of the cooperation on the action logic, and complex wiring of the overload shedding loops, etc. This can result saving on construction investment and operation and maintenance cost.2. Achieving the automatic identification of the substation operation mode and automatically established the corresponding action logic of the spare automatic switch system of substation domain, which can greatly improve the equipment from the adaptability on the flexible operation mode, reducing the substation operation and maintenance personnel workload, reduce operating risk on the power grid.3. Achieving the overload load-shedding anticipation function of the main transformer. The secondary circuit of the main transformers is simplified by implementing the on the overload load-shedding function of the main transformers in the system of the spare automatic switch system of substation domain.