Determining P-Q Droop Coefficients of Renewable Generators for Voltage Regulation in an Islanded Microgrid

In this paper, we propose a novel method for determining the active power-reactive power (P-Q) droop coefficients of renewable generators in an islanded microgrid. Intermittent output power of a renewable generation causes voltage deviation. For voltage regulation, P-Q droop has considerable effect. The calculation of P-Q droop coefficients is based on the voltage sensitivity value derived by Jacobian matrix. To achieve the desired P-Q droop coefficient, it is necessary to reflect active power-frequency (P-f) and reactive power-voltage magnitude (Q-V) droop scheme widely used in an islanded microgrid. The P-f droop characteristic is applied by regarding the renewable generator as a slack bus and the Q-V droop characteristic is applied by adding the additional term to Jacobian matrix. The proposed method was modeled and simulated by MATLAB/Simulink to prove its effectiveness.