A Virtual Negative Inductor Stabilizing Strategy for DC Microgrid With Constant Power Loads

In this paper, a novel virtual negative inductor stabilizing strategy is proposed for the dc microgrid with constant power loads. It is known that in the dc-based power system, the constant power load will generate a virtual negative incremental resistance, which may deteriorate the whole system stability. The situation will be more serious for the dc power system with a large line inductance. In the proposed stabilizing strategy, a virtual negative inductor is built on the source-side converter through the droop control method. The built virtual negative inductor counteracts the large line inductance, thus enhancing the system damping effect. Small-signal models of the studied dc microgrid system under the proposed stabilizing strategy are carefully derived. A root-locus-based parameter designing approach is proposed for obtaining the optimal parameter value for the stabilizer. An explicit Nyquist stability criterion for the studied dc microgrid system is proposed, with the system minor loop gain carefully derived. Several comparative stability analyses are taken for showing the system robustness to the parameter perturbations. Detailed numerical simulations are also conducted for validating the effectiveness of the proposed stabilizing strategy.