Research On The Static Transfer Switch And New Control Technology

With the development of technology, power customers' request of power quality gets more and more severe. Because of the impulsive loads , non-linear loads, asymmetric loads and electronic equipments widely used, the power quality of power grid is being deteriorated, kinds of power quality problems happens frequently .Voltage sag is the most serious problem, which causes that equipment work abnormally and large amount of loss economical.STS is one kind of equipment base on custom power technology, and it provides economic and effective plan for improving the power quality. This paper introduced the base principal and main circle of STS, and deep researched on some of the technologies. For transfer strategy a new method based on LC resonant circle is proposed, which help transfer fast and quickly between two sources. The feature of the new method is recycling the surplus power through the reversed thyristor, which reduced the impulse caused by power poured into load, without series connected diode in the power circle, which avoided extra losses. In the aspect of power quality detection, introduced some general algorithms for voltage sags detection, and lay emphasis on that based onα-β/d-q transform. The simulation result of MATLAB proved that algorithms based onα-β/d-q transform detects voltage sag in real-time with low computation, but sensitive to noises and harmonics. A new algorithm based on kalman filter and short time correlation transform is proposed, and it's robust to noises, harmonics and small frequency deviation, and detects voltage sags fast. Participate in the design of the prototype, tests shows that the method proposed in the paper works well.