Research On Digital Simulation To HVDC Light System And Its Control Strategy

HVDC Light is a kind of new DC transmission technology developed from the traditional HVDC, with Voltage Source Converter (VSC) and IGBT as main components. The basic principles of VSVPWM are studied, and an approach to simulate VSVPWM based on PSCAD/EMTDC is put forward in this thesis. The steady state model of HVDC Light is set up. The correlations between control variables and controlled variables are figured out according to this model, then a PID controller to HVDC Light system is designed. The simulation results of a HVDC Light system based on VSVPWM and PID controller verify the feasibility of VSVPWM and PID controller to HVDC Light systems. The power flow model of HVDC Light system is also proposed, and a power flow calculation program incorporating with HVDC Light is developed, based on PSASP/UPI. The EPRI 7-bus test system is applied to test the proposed model and algorithm, and the results prove it feasible and correctness.