Counterintuitive VSM Behavior under CVR Incorporating Distribution System
For power system operators, this paper highlights a potential adverse effect of CVR on voltage stability, challenging conventional assumptions.
This paper investigates the impact of conservation by voltage reduction (CVR) on voltage stability margin (VSM) in transmission and distribution systems, finding counterintuitively that CVR reduces VSM due to increased effective impedance. Co-simulation results with IEEE 9-bus and 123-bus systems demonstrate this effect under various distributed generation modes.
This paper analyses the impact of conservation by voltage reduction (CVR) on voltage stability margin (VSM) considering transmission and distribution (T&D) systems. VSM is determined by P-V curve analysis using PSSE and GridLAB-D solvers to co-simulate the T&D systems under CVR and No CVR conditions. ZIP loads with profile [ZIP] = [0.4 0.3 0.3] are used to model the load. The paper discusses the counterintuitive result: under CVR, the VSM is reduced. Theoretical justification for the reduced VSM under CVR is the increase in the effective impedance between generation and load and this is proved using an extended 2-bus system. The paper shares T&D co-simulation results with IEEE 9-bus transmission system and a larger 123-bus distribution system and with distributed generation (DG) in unity power factor (UPF) and volt-VAR control (VVC) mode.