Research On LOEC Simplified In Measurement Channels

This thesis focuses on the application of the linear optimal excitation controller. The main works are as follows:1)The basic idea of optimal control is introduced here, especially linear optimal control. For the special research object to power system LQ state feedback technique is chosen. The H-P equation which determined the law of normal closed control system is also presented. Based on the theory introduced before, the optimal condition is given, with LQ index for linear time-variant control system or linear time-invariant control system. The means and steps to design linear optimal controller is finally developed.2)Based on a state-space equation model of one machine-infinite bus system, an additional state variable is presented and an improved linear model is obtained. By the means of linear optimal controller design introduced in chapter 2 a linear optimal excitation controller (LOEC) is designed based on the improved linear model, the LOEC is simplified then with the feedback variables simplified, and the deviation of active power ΔPG and terminal voltage ΔVG of synchronous machine, which areeasier to be measured, is reserved. So with ΔPG, ΔFG, \ΔPGdt, \ΔVGdt as thefeedback variable of excitation controller, a LOEC is designed, the measurement channels are reduced to 2, which is used to be 4. Because the state variable ΔPG is included, the designed LOEC can improve the damping of electromechanical mode oscillation in power system, and because of ΔFG the LOEC has the ability of fast modulation for terminal voltage of synchronous machine.3)A dynamic simulation tool of SIMPOW(SIMulation and analysis of electrical POWer systems) is introduced, and with this powerful simulation tool the linear optimal excitation controller simplified in measurement channels is simulated and tested, also analysis for the simulation is given.4)The power system stabilizer(PSS) and linear optimal excitation controller(LOEC) are both used to damp electromechanical mode oscillation in power system, and they are both effective means with their own excellent characteristics. LOEC has good robustness but PSS is more practical and is easy to be realized. So whether the excellent characteristic of the two different controllers can be synthetized is an interesting task. Chapter 5 explored this question in some extent, the LOEC designed in chapter 3 is transformed to the standard excitation model of AVR+PSS, then with the transformed model simulation and result analysis are carried out.