Wide-area measurement system control to coordinate HVDC links in large scale power systems

The paper develops wide-area measurement coordinated control for several high-voltage direct current (HVDC) links. The coordinating state-feedback controller is designed based on an estimated reduced order model aiming to improve the damping of the power oscillations. The controllable input signals are the set-points, active power or DC current, of the HVDC links. The wide-area signals are the measured speed signals of selected generators supplied by Phaser Measurement Units (PMUs). The PMU signals are used to estimate the current state of the model, i.e. the state of the system, and an appropriate control action can then be performed to dampen the system. The benefit of the presented method is that the used output signals, i.e. the used PMU signals, are independent of the system equilibrium and therefore makes it possible to use a state-feedback controller, i.e. coordinated control. The method is applied to the Cigre Nordic 32-bus system including two HVDC links, and shows that the damping can be significantly increased.