Automatic voltage regulation for photovoltaic systems
View Patent ↗A photovoltaic system includes solar cells and photovoltaic inverters configured to convert direct current generated by the solar cells to alternating current. Grid voltage at the point of interconnection (POI) of the photovoltaic system and the power grid is measured and compared to a setpoint. A control signal is generated based on the measured grid voltage. The control signal is provided to the photovoltaic inverters. The control signal is adjusted to cause the photovoltaic inverters to generate or absorb reactive power to respond to transient grid voltage changes.
1. A method of automatically regulating voltage generated by a photovoltaic system, the method comprising: measuring a voltage provided by a photovoltaic system at a point of interconnection (POI) of the photovoltaic system with a power grid; providing a control signal to control operation of a photovoltaic inverter or a reactive power source, wherein the control signal is based on the measured voltage; and adjusting the control signal to adjust a reactive power output of the photovoltaic inverter or the reactive power source in response to a change in the measured voltage.
2. The method of claim 1 , wherein said providing the control signal includes providing a reactive power setpoint to the inverter or to the reactive power source.
3. The method of claim 2 , wherein said adjusting the control signal reduces a difference between the reactive power output and the reactive power setpoint.
4. The method of claim 1 , wherein adjusting the control signal comprises:
adjusting the control signal to make the photovoltaic inverter absorb or export reactive power based on a difference between the measured voltage and a reference voltage.
5. The method of claim 1 , wherein said providing the control signal comprises providing a voltage signal to the photovoltaic inverter.
6. A photovoltaic system, comprising:
a plant controller configured to receive a measured voltage measured at a point of interconnection (POI) of the photovoltaic system with a power grid, and to provide a parameter associated with the measured voltage to an inverter or to a reactive power source to adjust a reactive power output of the inverter or the reactive power source.
7. The photovoltaic system of claim 6 , wherein the parameter associated with the measured voltage is a reactive power setpoint.
8. The photovoltaic system of claim 6 , wherein the plant controller is configured to provide the reactive power setpoint to the photovoltaic inverter in digital form over a data communications network.
9. The photovoltaic system of claim 6 , wherein the plant controller is configured to provide the parameter to adjust the reactive power output of a capacitive bank.
10. The photovoltaic system of claim 6 , further comprising a meter configured to measure the measured voltage at the POI.
11. The photovoltaic system of claim 6 , further comprising a plurality of switches providing data communication links between the plant controller and the inverter or the reactive power source.
12. The photovoltaic system of claim 6 , wherein the parameter is an inverter reference voltage, wherein the plant controller is configured to limit a rate of change of the inverter reference voltage.
13. The photovoltaic system of claim 12 , wherein the plant controller is configured to limit the inverter reference voltage based, at least in part, on a comparison of reactive power generated by the photovoltaic inverter and reactive power generated by other photovoltaic inverters in the photovoltaic system.
14. A photovoltaic system, comprising:
a plurality of photovoltaic modules;
a plurality of inverters configured to convert direct current generated by the plurality of photovoltaic modules to alternating current; a meter configured to measure a voltage at a point of interconnection (POI) of the photovoltaic system with a power grid; and
a controller configured to receive the measured voltage, and to provide a parameter associated with the measured voltage to an inverter or to a reactive power source to adjust a reactive power output of the inverter or the reactive power source.
15. The photovoltaic system of claim 14 , wherein the parameter associated with the measured voltage is a reactive power setpoint.
16. The photovoltaic system of claim 14 , wherein the controller is configured to provide the reactive power setpoint to the photovoltaic inverter in digital form over a data communications network.
17. The photovoltaic system of claim 14 , wherein the reactive power source is a capacitive bank.
18. The photovoltaic system of claim 14 , wherein parameter is an inverter reference voltage, wherein the plant controller is configured to limit a rate of change of the inverter reference voltage.
19. The photovoltaic system of claim 14 , wherein the controller is configured to limit the parameter based, at least in part, on a comparison of reactive power generated by the photovoltaic inverter and reactive power generated by other photovoltaic inverters in the photovoltaic system.