Coordinated Volt-VAR control in active distribution systems for renewable energy integration

A Volt-VAR control (VVC) strategy by using voltage regulators and reactive power compensators in the modern distribution grid for renewable energy integration is presented in this paper. Currently, the VVC techniques are gaining renewed interest and attention due to the emergence of active distribution grid, which refers to the distribution grid with advanced capability of computation, control and communication. The mathematical model of the distribution systems contains the detailed modeling of various distributed generators, in particular renewable energy sources such as wind and solar power generators, and the varying load over the continuous time period. The coordinated VVC control strategy adjust the value of the voltage regulator and the reactive power injection to minimize the voltage deviation and the overall power loss. A VVC control algorithm is developed to mitigate the voltage sag or swell associated with the intermittent renewable power output and load variation. The proposed VVC control strategy is implemented in the simulation environment of Matlab and GridLAB-D featured by detailed distributed generation and load models. The simulation results validate the effectiveness of the proposed VVC control strategy in terms of voltage flattening and power loss reduction. The load voltage and line losses can be limited within the allowed regulation range as a large scale renewable energy is integrated into the test multi-level distribution systems.