Studies On Optimally Designing Supplementary WADC Of FACTS Devices In Time Delayed Power System

Wide-area measurement system (WAMS) can provide real-time measurements, such as generator angle and speed, power flow on tie lines, which provides a new data platform and control means to design wide area damping controller (WADC) to damp inter-area power oscillations. However, the time delay is inevitably introduced during the transmission of wide-area measurements. Time delay can deteriorate the effectiveness of wide-area damping controller, and even cause system instability. Therefore, the effect of time delay on performance of controller and stability of system has to be taken into account when the WADC is designed.This thesis focuses on the optimal design of supplementary WADC of flexible alternating current transmission system (FACTS) devices and high voltage direct current (HVDC) transmission systems. The method for calculating eigenvalues of time-delayed system based on solution operator discretization (SOD) is studied. Then, the method is applied to calculate the rightmost critical eigenvalues of power system equipped with FACTS devices or HVDC transmission systems. Lastly, WADC is optimally designed.The main research work is addressed as follows.(1) The SOD-based method for calculating eigenvalues of time-delayed system is studied. The eigenvalues of time-delayed system located in the left (right) half complex plane are mapped to those of solution operator in z plane inside (outside) the unitary circle. Firstly, based on linear multistep discretization scheme, the infinite dimensional solution operator is discretized into an approximate matrix with finite dimension. Secondly, through calculating the part eigenvalues with the largest moduli of the discretization matrix, the estimates to eigenvalues of delayed system with the biggest real parts are indirectly obtained. Lastly, by Newton correction, the rightmost critical eigenvalues of the time-delayed system are accurately calculated;(2) For typical FACTS devices (SVC and TCSC) and HVDC transmission systems, their principles are analyzed and their steady and dynamic mathematic models are established. Then, power flow and small signal stability of the system are analyzed.(3) In order to endow WADC with good controllability and observability for the target mode, the approach based on joint controllability/observability mesure is investigated, by which the best locations of FACTS devices and feedback signals are selected. The method lays a solid foundation for further WADC design;(4) Considering the time delay impacts, the mathematical model for optimally designing WADC is built whose objective is maximizing the damping of the targetted critical oscillation mode. Then the problem is solved by the PSO algorithm.(5) The effectiveness of the proposed approach for optimally designing WADC by taking time delay impacts into account is validated on the 16 machine 68 bus test system with SVC, TCSC and HVDC transmission systems embedded.The proposed method for optimally designing supplymentay WADC of FACTS devices and HVDC transmission systems overcomes shortcomings of the traditional pole placement-based method for designing wide-area power sytem stabilizers and robust daming controller, where model reduction and delay approximation are required. Furthermore, there is no conseration in the proposed method.