Implementation of Conventional Controllers in HVDC Links for Improvement of the Power System Stability

In recent years, the trend has been toward simpler models like DC system for stability programs. A DC link is highly controllable; this unique characteristic of the DC line is used to increase the value of the transient stability of the AC systems. Hence, it is proposed to incorporate the DC link with conventional controllers like proportional and proportional integral controllers to maintain the system transient stability by controlling the power flow through DC link. DC links can be represented as algebraic equations, and the interface between AC and DC systems is treated in a manner similar to that described for power flow analysis as in conventional power flow analysis. It is assumed that reactive power in injected at the AC terminals of the converters, the power flows are simulated by Newton–Raphson method, and the stability analysis is carried out by point-by-point method.