Inverter-Less Hybrid Voltage/Var Control for Distribution Circuits With Photovoltaic Generators

This paper proposes a hybrid voltage/var control (VVC) architecture for distribution systems with a high PV penetration. The architecture consists of two control loops: coordinated normal control loop and uncoordinated transient cloud movement control loop. In the first loop, hourly dispatches are scheduled for on-load tap changer (OLTC), capacitor banks (CBs), and static var compensators (SVCs) based on forecasted load and PV power output so as to minimize power losses and voltage deviations. The second loop is triggered when large variations of PV power output caused by rapid cloud movement happen. All SVCs and CBs become self-controlled based on local voltage measurements with the single control objective to minimize voltage deviations. SVCs will operate firstly to flatten the voltage profile. If SVCs fail, CBs will switch to provide reactive power support. A time-adaptive delay is applied to each CB to avoid overcompensation. Case studies show the proposed method can optimize the system operation and is effective in voltage regulation with PV generators.