Method and apparatus for coordination of generators in droop controlled microgrids using hysteresis

Patent metadata

Field	Value
Publication number	US-2017194792-A1
Application number	US-201715398110-A
Country	US
Kind code	A1
Filing date	Jan 4, 2017
Priority date	Jan 6, 2016
Publication date	Jul 6, 2017
Grant date	—

Abstract

A method and apparatus for autonomously operating a microgrid power generator. In one embodiment, the method comprises obtaining a first measurement of at least one grid parameter of a microgrid transmission line coupled to a power generator in a microgrid; comparing the first measurement to a turn-on threshold; initiating, when the first measurement is less than the turn-on threshold, power generation by the power generator; obtaining, after initiation of the energy generation, a second measurement of the at least one grid parameter of the microgrid transmission line; comparing the second measurement to a shut-down threshold that is greater than the turn-on threshold; and stopping, when the second measurement exceeds the shut-down threshold, the power generation by the power generator.

First claim

1 . A method for autonomously operating a microgrid power generator comprising:
obtaining a first measurement of at least one grid parameter of a microgrid transmission line coupled to a power generator in a microgrid; comparing the first measurement to a turn-on threshold; initiating, when the first measurement is less than the turn-on threshold, power generation by the power generator; obtaining, after initiation of the energy generation, a second measurement of the at least one grid parameter of the microgrid transmission line; comparing the second measurement to a shut-down threshold that is greater than the turn-on threshold; and stopping, when the second measurement exceeds the shut-down threshold, the power generation by the power generator.

2 . The method of claim 1 , wherein the at least one grid parameter is the frequency of the microgrid transmission line.

3 . The method of claim 2 , wherein the shut-down threshold exceeds the turn-on threshold by an amount greater than the magnitude of an expected frequency change to the frequency of the microgrid that results from initiating the power generation.

4 . The method of claim 3 , where the magnitude of the expected frequency change is based on a minimum operating power of the power generator.

5 . The method of claim 2 , wherein the turn-on threshold is less than a frequency set point for activating energy retrieval from at least one storage asset of the microgrid.

6 . The method of claim 2 , wherein the turn-on threshold is less than a frequency set point for activating power generation by a distributed energy resource (DER) of the microgrid.

7 . Apparatus for autonomously operating a microgrid power generator comprising:
a generator controller for:
obtaining a first measurement of at least one grid parameter of a microgrid transmission line coupled to a power generator in a microgrid;
comparing the first measurement to a turn-on threshold;
initiating, when the first measurement is less than the turn-on threshold, power generation by the power generator;
obtaining, after initiation of the energy generation, a second measurement of the at least one grid parameter of the microgrid transmission line;
comparing the second measurement to a shut-down threshold that is greater than the turn-on threshold; and
stopping, when the second measurement exceeds the shut-down threshold, the power generation by the power generator.

8 . The apparatus of claim 7 , wherein the at least one grid parameter is the frequency of the microgrid transmission line.

9 . The apparatus of claim 8 , wherein the shut-down threshold exceeds the turn-on threshold by an amount greater than the magnitude of an expected frequency change to the frequency of the microgrid that results from initiating the power generation.

10 . The apparatus of claim 9 , where the magnitude of the expected frequency change is based on a minimum operating power of the power generator.

11 . The apparatus of claim 8 , wherein the turn-on threshold is less than a frequency set point for activating energy retrieval from at least one storage asset of the microgrid.

12 . The apparatus of claim 11 , wherein the at least one storage asset is an AC battery comprising a bidirectional DC-AC inverter.

13 . The apparatus of claim 8 , wherein the turn-on threshold is less than a frequency set point for activating power generation by a distributed energy resource (DER) of the microgrid.

14 . The apparatus of claim 13 , wherein the DER comprises a plurality of photovoltaic (PV) modules couples to a plurality of DC-AC inverters.

15 . A computer readable medium comprising a program that, when executed by a processor, performs a method for operating a microgrid power generator, the method comprising:
obtaining a first measurement of at least one grid parameter of a microgrid transmission line coupled to a power generator in a microgrid; comparing the first measurement to a turn-on threshold; initiating, when the first measurement is less than the turn-on threshold, power generation by the power generator; obtaining, after initiation of the energy generation, a second measurement of the at least one grid parameter of the microgrid transmission line; comparing the second measurement to a shut-down threshold that is greater than the turn-on threshold; and stopping, when the second measurement exceeds the shut-down threshold, the power generation by the power generator.

16 . The computer readable medium of claim 15 , wherein the at least one grid parameter is the frequency of the microgrid transmission line.

17 . The computer readable medium of claim 16 , wherein the shut-down threshold exceeds the turn-on threshold by an amount greater than the magnitude of an expected frequency change to the frequency of the microgrid that results from initiating the power generation.

18 . The computer readable medium of claim 17 , where the magnitude of the expected frequency change is based on a minimum operating power of the power generator.

19 . The computer readable medium of claim 16 , wherein the turn-on threshold is less than a frequency set point for activating energy retrieval from at least one storage asset of the microgrid.

20 . The computer readable medium of claim 16 , wherein the turn-on threshold is less than a frequency set point for activating power generation by a distributed energy resource (DER) of the microgrid.

Assignees

• Enphase Energy Inc

Inventors

• Zimmanck Donald Richard
• Fornage Martin
• Harrison Michael J
• Rowe Christopher

Classifications

• H02J3/381 Primary

  Dispersed generators · CPC title

• H02J3/38

  Arrangements for feeding a single network from two or more generators or sources in parallel; Arrangements for feeding already energised networks from additional generators or sources in parallel · CPC title

• H02J2101/24

  Photovoltaics · CPC title

• H02J13/1335

  involving a local wireless network, e.g. Wi-Fi®, ZigBee® or Bluetooth® · CPC title

• H02J13/1311

  using the power network as support for the transmission · CPC title