Research On Fuzzy Control Of Voltage And Reactive Power In Substation

The requirement on the power quality is becoming higher and higher with the development of society. The voltage is an important indicator for power quality and is directly related to safety, stability and economy of the grid. The reactive power is the main factor in affecting the voltage. In order to improve the grid safety and economy, voltage and reactive power control is becoming more and more important.In grid, transformer substation takes charge of the voltage and reactive power control with On-Load Tap-Changer Transformer and parallel capacitors. The target of voltage and reactive power control is not only ensuring voltage qualified and reactive power balanced, but also decrease the adjust times of transformer and capacitors. Now the main control method is nine-zone diagram method in substation. It easily causes oscillate of adjust easily when the voltage or reactive power near the boundary, which increases the adjust times and affect the safety and economy of the grid.This paper introduces the basic theory of the voltage and reactive power control firstly, especially the advantage and disadvantage of the nine-zone diagram method and improved method base on nine-zone diagram, which are the main control methods in substation of Harbin. The model of the voltage and reactive power control is complex. As fuzzy control doesn't need exact model, it is used to improve the voltage and reactive power control in this paper.This paper designs a two-input and two-output fuzzy voltage and reactive power controller according to the fuzzy theory. The inputs are the bus voltage of the load side and the reactive power of primary side, and the outputs are the control signal of the OnLoad Tap-Changer Transformer and parallel capacitors. The fuzzy rule was instituted according to basic theory of the voltage and reactive power control and experience.This paper introduces how to do power simulation with MATLAB Sim Power Systems Blockset and how to realize the fuzzy controller in MATLAB fuzzy box. In this paper, fuzzy voltage and reactive power control and the nine-zone diagram method are both simulated in 66 kV bus. The result of the simulation demonstrates that the fuzzy controller can effectively decrease the action times of equipment and improve the voltage quality and reactive power distribution compare to nine-zone diagram method.