Renewable energy power generation systems
We describe a modular adjustable power factor renewable energy inverter system. The system comprises a plurality of inverter modules having a switched capacitor across its ac power output, a power measurement system coupled to a communication interface, and a power factor controller to control switching of the capacitor. A system controller receives power data from each inverter module, sums the net level of ac power from each inverter, determines a number of said capacitors to switch based on the sum, and sends control data to an appropriate number of the inverter modules to switch the determined number of capacitors into/out of said parallel connection across their respective ac power outputs.
1. A power conditioning system for supplying AC power to an AC grid comprising:
a plurality of inverters, each of the plurality of inverters including a DC input for receiving DC power from an DC source and an AC output for supplying AC power; and
a controller configured to:
determine an AC power supplied by each inverter of the plurality of inverters;
calculate a total power supplied by the power conditioning system as a percentage of a total power capability of the power conditioning system; and
control a displacement power factor of the power conditioning system based on the percentage.
2. The power conditioning system of claim 1 , wherein each inverter of the plurality of inverters includes an output capacitance that can be coupled in parallel with the AC output of each respective inverter.
3. The power conditioning system of claim 2 wherein a plurality of switching devices, one switching device for each respective inverter, controls the coupling of each output capacitance in parallel with the AC output of each respective inverter.
4. The power conditioning system of claim 3 wherein the plurality of switching devices comprise triacs.
5. The power conditioning system of claim 3 wherein the displacement power factor of the power conditioning system is controlled by controlling the plurality of switching devices.
6. The power conditioning system of claim 5 wherein the controller provides a variable degree of power factor compensation by controlling each of the plurality of switching devices for a portion of an AC cycle.
7. The power conditioning system of claim 1 wherein the controller is further configured to recognize when an inverter is added or removed from the plurality of inverters and compensate accordingly to maintain control of the displacement power factor of the power conditioning system.
8. The power conditioning system of claim 1 wherein the controller communicates with each inverter of the plurality of inverters through a wireless communication network.
9. The power conditioning system of claim 1 wherein the controller applies a threshold to the percentage such that when the percentage is below the threshold no compensation is performed, and when the percentage is above the threshold power factor compensation is employed to control the displacement power factor.
10. The power conditioning system of claim 1 , wherein each inverter of the plurality of inverters includes an inductor that can be coupled in series with the AC output of each respective inverter.