Research On Comparison Of AGC Control Strategies Under CPS

Developing large interconnected power grids is a common ways for every country. It is a natural trend for large interconnected power grids to become trans-region and trans-country. It is the control performance standard & control strategy of AGC(automatic generation control) that affects whether the quality of power grid frequency can be kept and improved, whether the power transfer of tie line can be kept normally, whether the performance of controlling unit can be improved, whether the advantages of large power grid can be played its full part.This paper states the tie-line load frequency bias control principle briefly at first, and introduces the background, fundamental and the control process of AGC. It also introduces two standards about how to evaluate the control performance of AGC, that is, A & CPS. What's more, the author also analyzes and compares the features of those two standards. This paper points out some problems of conflicts between the same cost in CPS index and different cost in AGC, by analyzing the application, organizational process, and price system of AGC ancillary service market. Because of these conflicts, AGC units may be controlled piecewise by certain ways in a certain area. Deficiency AGC units are chosen in the period of time when AGC regulation is difficult and AGC cost is expensive. If this strategy can satisfy CPS, the area will lighten the stress of AGC partly and save AGC cost, but the quality of grid frequency will be worse and the whole benefit of interconnected power grids will be damaged.In order to test the possibility of these problems, the author studied the control strategies nowadays in the world and provides another two control strategies of AGC. One is considering the cost of AGC, the other isn't. By using the simulating software (Simulink), this paper sets up a simulating system of interconnected power grids between two areas, and runs it. The results which includes CPS index, regulating times of AGC units, generation power, the cost of AGC, the frequency of interconnected system prove that the two strategies provided are fit for the requirements of CPS and the problems mentioned above actually exist.Finally, in order to avoid these problems and improve the quality of grid frequency, the author suggests that CPS can be weighted piecewise. And in that way, CPS can make AGC regulation work much more effectively.