Research And Developmend Of The Observing And Controlling Instrument

According as the new demand of distribution observing and controlling applied in the power supply business, developing the new generation distribution observing and controlling instrument, based on high-speed LPC2220FBD144 fixed-point number Advanced RISC Machines (ARM). In this paper, the hardware circuit design, the sample data handle methods, the software design thinking and the realization technique of the observing and controlling instrument is described in detail. After shape test and actual application, the circuit design of the instrument, the algorithm and the realization technique is feasible completely.This thesis includes several parts as fellows:(1) The development tendency and study status of observing and controlling instrument, the theory and control strategy of var compensation, and the detecting method of harmonic and reactive current are introduced. The project mainly studies swithching transient influences resulting from capacitors with difference connection mode during switching on and off, and interaction between harmonic and capacitor. Moreover, the method to solve these problems are put forward.(2) The design and character of hardware and software are introduced, which include control chip, detection and calculation, control and implement of switching and design of anti-interference. Besides, the design of hardware configuration is alse introduced, and the photo of controller is given out.In software design, analysis the harmonic of load voltage and current by Fast Foarier Transformation algorithm(FFT); using reactive power as the main switching criterion, and the total harmonic distertion of voltage and current as the auxiliary switching criterion, eliminates the oscillation in the process of capacitor switching under the light load; and avoids the breakage of capacitors due to the excessive harmonic; at the same time, alse designs a man-machine interface and a communication interface with upper machine.(3) The manufacture and test of the device is carried out, and the result identifies that the var compensation device can raise power factor, reduce reactive current and stabilize electric network voltage effectively. So the correctness of theory and the validity and practicability of the device are also proved.Finally, the design, the developing process and the result are summed up. The merit and disadvantage of the Var compensation device are pointed, and the direction and method of improvement are proposed.