Stability Analysis for Secondary Voltage Control of Microgrids Considering Communication Delays

Secondary voltage control is widely used in autonomous microgrids. The communication delays between the microgrid central controller (MGCC) and the primary local controller are inevitably generated due to factors such as data transmission, processing latency, and network constraints. These communication delays will reduce the performance of the system and even lead to system instability. To solve this problem, an innovative method is proposed to evaluate the impact of communication delays on the stability of the microgrid secondary voltage controller in this paper. First, a small-signal model of the autonomous microgrid with proportional integral (PI) secondary voltage controllers is constructed by MATLAB. Then, by using a Pade approximation method, the transcendental equation of the system can be solved. The eigenvalues of system with communication delay can be calculated and the stability of the system can be assessed. To validate the analytical results, a simulation model that includes communication delays is simulated in SIMULINK. Finally, The delay margin can be obtained by plotting the root locus of the time delay system. At the same time, the margin of control parameters can be obtained by plotting the root locus of the time delay system when the time delay is random.