Measurement-Based Wide-Area Damping of Inter-Area Oscillations based on MIMO Identification

Abstract: Interconnected power grid exhibits oscillatory response after a disturbance in the system. One such type of oscillations, the inter-area oscillations has the oscillation frequency in the range of 0.1 to 1 Hz. The damping of inter-area oscillations is difficult with local controllers, but it can be achieved using a Wide Area Damping Controller (WADC). For effective control, the input to the WADC should be the most observable signal and the WADC output should be sent to the most controllable generator. This paper presents a measurement-based novel algorithm for multi-input-multi-output (MIMO) transfer function identification of the power system based on optimization to estimate such oscillation frequencies. Based on the MIMO transfer function the optimal control loop for WADC is estimated. The WADC design is based on the discrete linear quadratic regulator (DLQR) and Kalman filtering for damping of inter-area oscillations. Since the MIMO identification is based on actual measurements, the proposed method can accurately monitor changes in the power grid whereas the conventional methods are based on small-signal analysis of a linearized model which does not consider changing operating conditions. The overall algorithm is implemented and validated on a RTDS/RSCAD and MATLAB real-time co-simulation platform using two-area and IEEE 39 bus power system models.