This chapter discusses the effects of constant power loads ( CPLs) in DC-microgrids. Such loads are commonly observed in DC microgrids because of the extensive use of power electronic circuits to interface loads. As it is explained, due to their nonlinear nature, CPL creates a complex dynamic system that present two possible behaviors with an unstable equilibrium point unless power source convertor interfaces are properly controlled. In this chapter, both time domain and geometric control approaches that achieve stable equilibrium points in the presence of CPLs are explained. Passive approaches to compensate the destabilizing effect of CPLs are also discussed, but these approaches often lead to costly and bulky designs. Complex dynamics are also observed in rectifiers with CPLs, which often present excessively large output voltage variations.

Chapter Contents:

• 3.1 Dynamic characteristics of DC microgrids
• 3.2 DC microgrids stability analysis
• 3.3 Passive approaches for stabilization of DC microgrids
• 3.4 Control strategies for stable DC microgrids operation
• 3.5 Operation of rectifiers with instantaneous constant power loads
• 3.6 Summary
• References

Inspec keywords: DC power transmission; distributed power generation; power generation control; power system stability

Other keywords: destabilizing effect; power source convertor interfaces; DC microgrids; time domain control; passive approaches; load interfaces; rectifiers; power electronic circuits; geometric control; stabilization; stable equilibrium points; constant power loads; output voltage variations; unstable equilibrium point; complex dynamic system

Subjects: Control of electric power systems; Power system control; d.c. transmission; Stability in control theory; Distributed power generation