Grid synchronisation

• US 9,997,923 B2
• Filed: 10/19/2012
• Issued: 06/12/2018
• Est. Priority Date: 12/20/2007
• Status: Active Grant

• Current Assignee: Tesla Inc.
• Original Assignee: SolarCity Corporation (Tesla Inc.)
• Inventors: Amaratunga, Gehan Anil Joseph, Chisenga, Lesley, Viraj, Andrabadu
• Primary Examiner(s): Fureman, Jared
• Assistant Examiner(s): Dominique, Emmanuel R
• Application Number:
  US13/656,641
• Publication Number:
  US 20130134790A1
• Time in Patent Office: 2,062 Days
• Field of Search: 307 87, 322 24
• CPC Class Codes: H02J 2300/24 of photovoltaic origin
• CPC Class Codes: H02J 3/38 Arrangements for parallely feeding a single network by two or more generators, converters or transformers
• CPC Class Codes: H02J 3/381 Dispersed generators
• CPC Class Codes: H02J 3/388 Islanding, i.e. disconnection of local power supply from the network
• CPC Class Codes: H02J 3/40 Synchronising a generator for connection to a network or to another generator
• CPC Class Codes: H02J 3/46 Controlling of the sharing of output between the generators, converters, or transformers
• CPC Class Codes: H02J 3/48 Controlling the sharing of the in-phase component
• CPC Class Codes: H02J 3/50 Controlling the sharing of the out-of-phase component
• CPC Class Codes: Y02E 10/56 Power conversion systems, e.g. maximum power point trackers

Abstract

The invention relates to a grid synchronizer for connecting an AC output of a power converter to the AC grid mains. In one aspect the invention provides a grid synchronizer comprising an inverter controller to control an AC output of the inverter, the controller including a receiver to receive grid data from a grid sensor location remote from said inverter. In another aspect we describe techniques for rapid removal of charge from a control terminal of a power switching device such as a MOSFET, IGBT or Thyristor using a particular driver circuit.

Claims

1. A system comprising:

a plurality of inverters, each for converting direct current (DC) power to an alternating current (AC) output power having a current phase and for outputting the AC output power to an AC mains power supply, each inverter comprising a controller for controlling the AC output power from the inverter to the AC mains power supply;

a plurality of cables for coupling an inverter of the plurality of inverters to the AC mains power supply, each cable comprising a line impedance that is different from other cables of the plurality of cables; and

a grid sensor, coupled between the plurality of cables and the AC mains power supply, for sensing a set of grid characteristics comprising a modified current phase based on the different line impedances of the plurality of cables and a voltage phase of a line voltage of the AC mains power supply,

wherein each of the plurality of inverters has a receiver configured to receive the set of grid characteristics from the grid sensor; and

wherein each controller controls the AC output power from a respective inverter of the plurality of inverters by adjusting the current phase of the AC output power from the respective inverter to match the modified current phase.

2. The system of claim 1, wherein matching the modified current phase comprises overcoming the line impedance of a respective cable of the plurality of cables.

3. The system of claim 1, wherein the receiver is configured to receive the set of grid characteristics from the grid sensor over a wired communication network.

4. The system of claim 3, wherein the wired communication network communicates data through the plurality of cables.

5. The system of claim 1, wherein the receiver is configured to receive the set of grid characteristics from the grid sensor through a wireless communication network.

6. The system of claim 1, wherein each inverter of the plurality of inverters further comprises:

an inverter sensor for sensing inverter data comprising a set of inverter characteristics of the respective inverter.

7. The system of claim 6, wherein the set of inverter characteristics comprises at least one of the current phase of the AC output power of the respective inverter, a power output of the respective inverter and a power efficiency of the respective inverter.

8. A system for micropower generation, the system comprising:

a plurality of inverters, each inverter for converting direct current (DC) power from a power input to an alternating current (AC) output power having a current phase and for outputting the AC output power to an AC grid mains to provide the AC output power into the AC grid mains;

a plurality of cables for connecting each inverter of the plurality of inverters to the AC grid mains, each cable of the plurality of cables comprising a line impedance that is different from other cables of the plurality of cables; and

a grid sensor, remote from the plurality of inverters and used for sensing a set of grid characteristics of the AC grid mains and for wirelessly transmitting grid data relating to the sensed set of grid characteristics to each inverter of the plurality of inverters;

wherein the set of grid characteristics comprises a modified current phase based on the line impedances of each of the plurality of cables and a voltage phase of a line voltage of the AC mains power supply; and

wherein each inverter comprises a wireless receiver for receiving the transmitted grid data that the inverter uses to control the AC output power by adjusting the current phase of the AC output power to match the modified current phase.

9. The system of claim 8, wherein matching the modified current phase comprises compensating for the line impedance of a respective cable of the plurality of cables.

10. The system of claim 8, wherein the grid sensor is connected to the plurality of cables at a point where the AC output power from each of the plurality of inverters is combined and injected into the AC grid mains.

11. The system of claim 8, wherein the wireless receiver receives the transmitted grid data from the grid sensor through a wireless communication network.

12. The system of claim 8, wherein each inverter of the plurality of inverters further comprises:

an inverter sensor for sensing inverter data comprising a set of inverter characteristics of a respective inverter in order for the respective inverter to transmit the inverter data to the grid sensor located remote from the respective inverter.

13. The system of claim 12, wherein the set of inverter characteristics comprises at least one of the current phase of the AC output power of the respective inverter, a power output of the respective inverter and a power efficiency of the respective inverter.

14. A method comprising:

coupling a plurality of inverters to an alternating current (AC) grid mains through a plurality of cables;

converting, using the plurality of inverters, direct current (DC) power to an AC output power having a current phase;

transmitting the AC output power over the plurality of cables to the AC grid mains, each cable comprising a line impedance that is different from other cables of the plurality of cables;

receiving with a receiver disposed within each of the plurality of inverters a set of grid characteristics from a remote grid sensor that is coupled between the plurality of cables and the AC grid mains, the set of grid characteristics comprising a modified current phase based on the line impedance of each of the plurality of cables and a voltage phase of a line voltage of the AC grid mains; and

altering a current phase of the AC output power based on the set of grid characteristics in order to match the modified current phase.

15. The method of claim 14, wherein matching the modified current phase comprises overcoming the line impedance of each of the plurality of cables.

16. The method of claim 14 further comprising, at each inverter of the plurality of inverters:

sensing inverter data comprising a set of inverter characteristics of the AC output power of a respective inverter; and

transmitting the sensed inverter data to the remote grid sensor.

17. The method of claim 16, wherein the set of inverter characteristics comprises at least one of a phase of the AC output power, a power output of the respective inverter and a power efficiency of the respective inverter.