DC microgrid for interconnecting distributed electricity generation, loads, and storage
A device includes an energy unit coupled to an energy device and adapted to couple a pair of split DC rails. A controller senses the voltage on the DC rails and regulates its output current response by means of an autonomous current response that creates the aggregate effect of controlling the rail voltage in cooperation with other units coupled to the DC rails. A system includes multiple such devices coupled to split DC rails.
1. An energy unit comprising:
a voltage converter to couple between an energy device and a pair of split DC rails,
a controller to sense the voltage on the DC rails and smoothly regulate a current of the voltage converter to create an aggregate effect of controlling the DC rail voltage in cooperation with other energy units coupled to the DC rails.
2. The energy unit of claim 1 wherein the controller disconnects the voltage converter from the DC rails without damage when the DC rails are shorted together.
3. The energy unit of claim 2 and further comprising a ground fault detector to couple to the split rails of the DC bus.
4. The energy unit of claim 2 wherein the controller is programmed to disconnect the voltage converter form the DC rails in response to a fault detected by the ground fault detector.
5. The energy unit of claim 1 and further comprising a source of electricity coupled to the voltage converter as the energy device.
6. The energy unit of claim 5 wherein the source of electricity is at least one of a solar-powered source and a wind-powered source of electricity.
7. The energy unit of claim 5 wherein the controller without a linear ramp to zero power.
8. The energy unit of claim 1 and further comprising a sink of electricity coupled to the voltage converter as the energy device.
9. The energy unit of claim 8 wherein the sink of electricity is at least one of a load and an energy storage device.
10. The energy unit of claim 9 wherein the energy storage device comprises multiple identical batteries that equally share available power.
11. The energy unit of claim 1 wherein the converter regulates current by increasing or decreasing the current without turning off the energy unit.
12. An energy distribution system comprising:
a pair of split DC rails; and
multiple energy units coupled to the pair of split DC rails, each energy unit comprising:
an energy device;
a voltage converter coupled between the energy device and the pair of split DC rails; and
a controller to sense the voltage on the DC rails and smoothly regulate an output a current of the voltage converter to create an aggregate effect of controlling the DC rail voltage in cooperation with all the energy units coupled to the DC rails.
13. The energy distribution system of claim 12 and further comprising a ground fault detector to couple to the split rails of the DC bus to disconnect the voltage converter from the DC rails in response to a fault detected by the ground fault detector.
14. The energy distribution system of claim 12 and further comprising a switch coupled in series between the voltage converter and one rail of the pair of split DC rails to disconnect the voltage converter from the DC rails without damage when the DC rails are shorted together.
15. The energy distribution system of claim 12 wherein at least one energy device comprises a source of electricity and at least another energy device comprises a sink of electricity.
16. The energy distribution system of claim 15 wherein the source of electricity is at least one of a solar-powered source and a wind-powered source of electricity and wherein the sink of electricity is at least one of a load and an energy storage device.