System for use of static inverters in variable energy generation environments
A system to collect energy from generation systems such as, for example, wind farms or solar farms with widely distributed energy-generation equipment. In some cases, static inverters are used to feed the energy directly into the power grid. In some other cases, back-to-back static inverters are used create a high-voltage DC transmission line to collect power from multiple generation sites into one feed-in site.
1. A energy generation system, comprising:
one or more strings of variable energy collectors;
one or more string converters managed by a first controller to combine voltage outputs of the one or more strings of variable energy collectors into an energy output stream;
a bus configured to route the energy output stream;
a static inverter to which the bus routes the energy output stream, the static inverter comprising:
switches for converting the electrical energy output to an alternating current; and
a transformer arrangement comprising a transformer and a balancing transformer to convert the alternating current to an alternating current with a given voltage; and
a second controller configured to receive measurements of voltage phase on a grid and control timing of the switches in accordance with the measurements of the voltage phase.
2. The system of claim 1 , wherein said transformer arrangement outputs the alternating current with the given voltage.
3. The system of claim 2 , wherein the second controller sends data over a network about energy being output.
4. The system of claim 1 , wherein the second controller sends data to a supervisory site or receives data from the supervisory site.
5. The system of claim 1 , wherein the transformer arrangement is configured to generate three phase alternating current.
6. The system of claim 5 , wherein the transformer is a delta-wye-delta transformer.
7. The system of claim 1 , wherein the transformer arrangement comprises one or more filters to transform a waveform of the alternating current with the given voltage.
8. The system of claim 1 , wherein the second controller communicates with a network to send and receive data over the network regarding operation of the system.
9. The system of claim 1 , wherein the second controller includes the first controller.
10. An energy generation system, comprising:
one or more variable energy collecting units producing respective direct current (DC) voltage levels;
a bus;
a first controller in communication with the units to enable the DC voltage levels to be compatible on the bus,
a static inverter to which the bus delivers a DC compatible voltage level, wherein the static inverter converts the DC compatible voltage level to an alternating current;
a pulse width modulation inverter to receive an alternating current output of the static inverter; and
a second controller in communication with the static inverter and the pulse width modulation inverter to control the alternating current output from the static inverter to the pulse width modulation inverter.
11. The system of claim 10 , further comprising a capacitor in electrical communication with the bus.
12. The system of claim 10 , wherein a modified alternating current flow is output from the pulse width modulation inverter to a feeding point.
13. The system of claim 10 , wherein the second controller includes the first controller.
14. A energy generation system, comprising:
one or more variable energy collecting units to produce direct current (DC);
a bus;
a controller in communication with the units to maintain a desired voltage on the bus;
a first static inverter to which the bus delivers the DC, wherein the first static inverter converts the DC received from the bus to an alternating current; and
a second static inverter configured to receive the alternating current provided by the first static inverter and convert the alternating current received from first static inverter to a high voltage direct current.
15. The system of claim 14 , further comprising a filter to modify a waveform of the alternating current.
16. The system of claim 14 , further comprising a master static inverter receiving an output of the high voltage direct current to generate an alternating current for a power grid.
17. The system of claim 14 , wherein the controller is in communication with a grid.
18. The system of claim 14 , further comprising:
a high voltage direct current transmission line configured to receive the high voltage direct current generated at least by the second static inverter; and
a third static inverter configured to convert from a high voltage direct current received from the high voltage direct current transmission line to an alternating current at a feeding point.
19. The system of claim 18 , further comprising:
a fourth static inverter configured to convert from a direct current input to an alternating current output; and
a fifth static inverter configured to convert the alternating current output of the fourth static inverter to a high voltage direct current output to the high voltage direct current transmission line.
20. The system of claim 19 , wherein the fifth static inverter and the second static inverter power the high voltage direct current transmission line in parallel.