Delay Control Theory In Applied Research, Based On The The Wams Regional Power Grid In The Damping Control

The fast development and wide application of computer technology, network and communication technology in power system, which on one hand is driving the research of power system operation and control to the trend of wide-area, web-based and intelligent monitoring and control, promotes the advancement of the electric power industry application technique; on the other hand, while the interconnection of large-scale power system improves the economic performance of power systems, it also makes the dynamic process of interconnected system more complicated and threatens its operation security. Among these unsafe factors, inter-area low-frequency oscillation often is a serious bottleneck for increasing power transfer across interconnected power system, and it has been concerned intensively.At present, damping control is one of the main measures to restrain the low frequency oscillation and its main method is to put up power system stabilizer in the control circuit, namely PSS. While existing damping controllers provide inferior performance in dealing with this problem because of the only use of local measurement information. The rapid development of synchronous phasor measurement technology and wide-area measurement system, or WAMS, pave the way to accurately measure and quickly transfer relative power angles and rotor speeds of generators over the distance of a whole power system, and thus makes it possible to construct wide-area power damping feedback control systems by using wide-area measurements. The impact of time delays introduced by PMU signal transmission and processing in wide-area measurement system (WAMS) has to be considered.This paper presents a detailed overview of power system wide-area control considering the time delay in measurement and communication system, and then gives a LMI design method of wide-area power damping controller considering the impact of time delay. The simulation results show that this kind of damping controllers based on LMI can restrain the inter-area low frequency oscillation effectively. LMI method, especially the convex optimization approach based on LMI, as a new kind control algorithm, has been used widely in control system analysis and design. The problem that to be dealt with is expressed in or changed into the form of linear matrix inequality, and with the effective and reliable interior point algorithm, LMI method brings opportunities to those problems which have no analytic solutions or are difficult to get them in numerical calculation. The main works of this paper are listed as following:1. The paper carries on an overview of the background and main research methods about time delay in WAMS, and analyses the disadvantage of some method in practical application. In order to overcome these problems, the linear matrix inequality method is introduced and used in the design of damping controller.2. The synchronous phasor measurement technology based on GPS and wide-area measurement system, or WAMS, are introduced briefly. According to practical applications, several typical structures of WAMS are presented, and also it is indicated that it's feasible to use PMU measurement signals in wide-area damping control systems.3. It is put forward to use inter-area relative power angles and rotor speeds as AIADC's input signals to solve the inter-area low-frequency oscillation.4. The Power System Block, or PSB, in MATLAB/Simulink is presented. The modeling of the two-area four-machine power system to be controlled and the linearization of multimachine power system are also described in detail.5. The mechanism of power system low frequency oscillation and its suppression are recommended, and the algorithm based on LMI of wide-area damping controller considering the impact of time delay is presented, then the wide-area damping controller based on LMI is designed.