A Stabilization of Frequency Oscillations in a Parallel AC-DC Interconnected Power System via an HVDC Link

This paper presents a new application of High Voltage Direct Current (HVDC) link to stabilization of frequency oscillations in a parallel AC-DC interconnected power system. When an interconnected AC power system is subjected to a large load with rapid change, system frequency may be considerably disturbed and becomes oscillatory. By utilizing the system interconnections as the control channels of HVDC link, the tie-line power modulation of HVDC link through interconnections is applicable for stabilizing the frequency oscillations of AC systems. In the design of power modulation controller, the technique of overlapping decompositions and the eigenvalue assignment are applied to establish the state feedback control scheme. To evaluate control effects, a linearized model of a parallel AC-DC interconnected system, including a power modulation controller of HVDC link, is investigated by simulation study. Simulation results show that the proposed controller is not only effective in damping out frequency oscillations, but also capable of alleviating the transient frequency swing caused by a large load disturbance.