Study On The Basic Principles And Application Of Supplementary Excitation Damping Controller

As the long-distance and large-capacity transmission is more popular in modern power systems, series compensation is an effective solution to the problem of enhancing power transfer and improving system stability. However, if the resonant frequency of series compensated transmission network and the natural frequency of turbine-generator shaft complement each other (the sum is equal to synchronous frequency), it may result in subsynchronous resonance (SSR) and cause great damage to the shaft of generators. The supplementary excitation damping controller (SEDC) has proved to be one of the least expensive and convenient methods for mitigating SSR in power system. This thesis is focused on the basic principles and application of SEDC. The main work is as follows:(1) A generic SEDC control model is presented based on modal separation design method, and a novel method to construct the optimal feedback signal is also proposed. The design is made for Modal Filter as well as forming the optimal feedback signal through a Preprocessing Step to reduce the request for Modal Filter. Meanwhile, a type of recomanded SEDC control model is proposed in which gain and phase compensator can be designed separately without interaction. The corresponding relationship between the modal phase compensation and time constant of this recomanded SEDC model is also deduced.(2) An optimization design method for SEDC parameters which adapt various operation conditions is proposed. Construct a research system with the practical project background, study the optimization design method including the optimal phase compensation searching and gain setting for each SEDC modal control loop. On this basis, an improved particle swarm optimization algorithm for SEDC parameters design is proposed to effectively optimize the SEDC parameters, Based on the Learning Mechanism and the introduced Mutation Mechanism. Results of the eigenvalue analysis and time domain simulation validate the effectiveness and robustness of SEDC designed by this method in damping the multi-mode SSR.(3) The detailed excitation system model is built, which considers the power unit, in the time domain simulation model and frequency domain analysis model. On this basis, analyse the control mode of the power unit to meet the requirements of SEDC. Make characteristic analysis of the power unit and realize the interface between synchronous machine model and excitation regulator model in PSCAD/EMTDC. Quantitatively analyse the effect on SEDC performance from the triggering control mode and scanning period through frequency characteristic analysis and time domain simulation.(4) The strategy of dynamic Limiter to avoid the interference between SEDC and conventional excitation control function is proposed. Build the detailed excitation simulation model, which considers limiting device such as Under-Excitation Limiter, Over-Excitation Limiter and Voltage/frequency Limiter. And then quantitatively analyse the affect on excitation system conventional control function from SEDC thorugh electromagnetic transient simulation.(5) All-digital RTDS simulation test is performed to validate the effectiveness of SEDC as well as the theoretical study result through analysis on simulation result, and a Hardware-in-the-loop RTDS Simulation Platform for SEDC is proposed to lay the foundation for latter SEDC device research.