Supplementary DC control in a two area AC/DC power system

Abstract

In this thesis results of research are reported for a study of the dynamic performance of a two-area power system interconnected by AC and DC tie-lines. The system includes supplementary DC control interacting with the conventional AC area controls. Taldng advantage of the fast controllability of DC links, supplementary control utilizing DC power modulation improves system damping, reduces unnecessary governing system operation and reduces inadvertent energy interchange between the two areas. C power modulation is based on variations of AC system signals such as net po er interchange deviation and/or area frequency deviation.A linear model was used for the power system to study small changes around a base reference state and only the power/ frequency control aspects of the overall po er system control problems were considered. The model used and the simulation of it described in this thesis.Eigen-structure analysis of the state space model of the power system was used to evaluate system stability, with and without supplementary control. Control optimiza on was achieved by minimization of a performance index to adjust the values of the controller parameters. The performance index selected is a function of Area Con of Error (ACE) and is a good measure of control effectiveness. The results of the eig nstructure analysis and the control optimization are presented.Computer simulation was used to obtain power system dynamic responses to step load disturbances and to estimate optimal controller parameters. The simulation studies considered various AC and AC/DC interconnection types and control features of the two area interconnected power system. Simulation results are presented in the form of tilme responses graphs and in summary tables.It was found that the dynamic performance of the two-area power system could be significantly improved with the aid of the controls in the DC line.

Multi — Area AGC with AC/DC link and BES and Cuckoo Search optimized PID controller

“…A lot of research [4] - [7] has been done on the power system to investigate the effect of HVDC link to the system frequency. Authors in [4] - [6] studied the effect of HVDC link to the system frequency of a two area thermal system. In [7], dynamic performance of power system with diverse sources in each area and interconnected via parallel AC/DC transmission links is studied.…”

“…The tuned parameters for the Cuckoo Search algorithm for the system considered are (Number of nests) n = 25, Discovery rate of alien eggs/solutions, p a = 0.24. There values are selected based on the minimization of objective function given by equation(4).…”

An Experimentally Validated Nonlinear Stabilizing Control for Power Electronics Based Power Systems

“…The path chosen here is to modulate the commanded input power of the load converters at the appropriate frequencies with a nonlinear system stabilizing controller (NSSC). One possibility to accomplish this is to monitor the power passed down the AC transmission line [8] and from this measurement modulate the commanded converter/inverter input power. This requires additional sensors placed long distances from the converter/inverter.…”