Power Compensation Control for Interconnection of Weak Power Systems by VSC-HVDC

Using voltage-source converter high-voltage direct current (VSC-HVDC) to interconnect weak ac power systems has drawn much attention. Under the traditional vector control for the VSC that the response of AC voltage loop cannot match that of the active power loop may limit power transmission capability of the VSCs that interconnect with weak power systems. To enhance the power transmission capability and stability, this paper proposes a power compensation control that is based on the analysis of characteristics of power-voltage (PV) curves. This method can improve the damping control performance of the active power and the ac voltage by adjusting the compensated values adaptively. A small-signal model of the integrated system is established to study the performance of the proposed control method. The impact of the compensation coefficients and steady-state operating points on the system stability is studied. Motivated by an on-going back-to-back project in China, corresponding electromagnetic transient simulation models are constructed in MATLAB/Simulink environment to verify the effectiveness of the proposed method on the performance of operating limits, damping performance, disturbance withstanding capability, and fault ride-through capability.