Device Research And Design For Under Frequency Load Shedding Based On Embedded Microcontroller

The electric power system stability is the key to realize power network safe operation, once the stability is damaged, it will result in huge economic losses and disastrous consequences. Modern power systems are always the cross-regional interconnected system characterized by large scale, extra high voltage, long distance and large capacity units. It has been obviously improved to the reliability and economy of power system operation. The quality of system frequency of the cross-regional interconnected system can be obviously improved generally, however, once the system is suffered from a large disturbances, the frequency stability would be deteriorated sharply, so how to maintain the frequency stability to ensure the quality of supply during the system being suffered large disturbances has been widely focused.In the modern electric power system, under frequency load shedding is the last defense line that is used for ensuring the normal operation of electric power system, and being as the important measures to maintain the frequency stability of electric power system. Whatever at home or abroad the measures of under frequency load shedding has been widely applied in electric power system. In this paper, firstly it analyzed to the development dynamics of under frequency load shedding scheme and its device at home and abroad. Then it was studied to the dynamic/static frequency characteristics of electric power system and compared the measured frequency response characteristics of actual power system with the dynamic frequency response characteristics obtained by means of single generator with concentrated load analysis model. In the above the frequency response characteristics is different from each other, therefore there are some limitations when using single generator with concentrated load analysis model analyzes the dynamic frequency characteristics of electric power system. After that, it was made the comparison with advantages and disadvantages of various scheme of under frequency load shedding, and proposed a new scheme of under frequency load shedding. Finally it designed to the hardware system platform and software system platform. The following research works has been completed in this paper:â‘ Analyzed the dynamic/static frequency characteristics of electric power system. The conclusion is that the frequency of electric power system is directly related to whether or not the active load balancing with the electric power system supply. It made the substantial foundation for designing a under frequency load shedding device. â‘¡Proposed a quantitative method of whether or not load shedding for the device of under frequency load shedding. The load shedding criterion is that it is responded to system frequency and the time of system frequency change.â‘¢Designed a sort of new hardware platform for under frequency load shedding system. The hardware platform is based on 32-bit microcontroller MCF52235, which could be used for Ethernet communication environment.â‘£Designed a sort of software system platform for under frequency load shedding device. The software platform is based on the framework of"main program plus the interrupt for sampling plus the interrupt for the control of under frequency load shedding plus the interrupt for communication". This framework could ensure the data sampling in real time and the control of under frequency load shedding in time.