On design of a robust controller to mitigate CPL effect — A DC micro-grid application

It has been an established fact that the presence of Constant Power Load (CPL) in DC micro-grid causes instability as it has negative impedance characteristic. This poses a serious challenge for the stability of the DC micro-grid in spite of ensuring stability of individual converters. Some efforts are made by the community to address the issue. In this paper, we have proposed a sliding-mode controller with a non-linear sliding surface to ensure large signal stability. The proposed non-linear surface ensures that constant power is maintained by the converter. The proposed controller is able to mitigate CPL effect of tightly regulated POLs and ensures stable operation of DC micro-grid under various disturbances. Proposed controller is implemented on a typical DC micro-grid feeding a CPL. The theoretical development is verified through simulations in MATLAB Simulink environment.