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

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 satisfies 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 satisfies the shut-down threshold, the power generation by the power generator.

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 satisfies 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 satisfies 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 satisfies 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 satisfies 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 satisfies 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 satisfies 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.