Apparatus and method for reactive power control

Abstract

Apparatus and method for controlling reactive power. In one embodiment, the apparatus comprises a bidirectional power converter comprising a switched mode cycloconverter for generating AC power having a desired amount of a reactive power component.

1 . A bidirectional power converter comprising:
 a storage device for storing and releasing energy;   a DC bridge, coupled to the storage device, for producing a high-frequency AC signal;   a switched mode cycloconverter, coupled to the DC bridge, for converting the high-frequency AC signal to a low-frequency AC signal; and   a controller, coupled to the DC bridge and the switched mode cycloconverter, for controlling an amount of energy that is stored or released from the storage device to produce a desired amount of reactive power.   
     
     
         2 . The bidirectional power converter of  claim 1 , wherein the controller controls timing of switches within the DC bridge and the switched mode cycloconverter to control the amount of energy that is stored or released from the storage device to produce the desired amount of reactive power. 
     
     
         3 . The bidirectional power converter of  claim 1 , wherein the controller comprises a maximum power point tracking controller for controlling real output power and a reactive power controller for controlling reactive power output. 
     
     
         4 . The bidirectional power converter of  claim 1 , wherein the controller determines the desired amount of reactive power using a reactive power control schedule comprising a schedule of reactive power to be generated as a function of one or more of an AC grid voltage, a bidirectional power converter output power, or a change in AC grid voltage. 
     
     
         5 . The bidirectional power converter of  claim 4 , wherein the reactive power control schedule comprises a list of reactive power amounts and a corresponding time of day for generating each reactive power amount of the list of reactive power amounts. 
     
     
         6 . The bidirectional power converter of  claim 1 , wherein the bidirectional power converter is a static VAr compensator. 
     
     
         7 . The bidirectional power converter of  claim 1 , wherein the switched mode cycloconverter is one of a single-phase cycloconverter or a three-phase cycloconverter. 
     
     
         8 . The bidirectional power converter of  claim 1 , wherein an input is coupled to a DC power source comprising a battery or a solar panel. 
     
     
         9 . A method of controlling reactive power comprising:
 storing energy using a storage device;   producing a high-frequency AC signal using a DC bridge coupled to the storage device;   converting the high-frequency AC signal to a low-frequency AC signal using a switched mode cycloconverter coupled to the DC bridge; and   controlling, using a controller coupled to the DC bridge and the switched mode cycloconverter, the DC bridge and the switched mode cycloconverter to control an amount of energy that is stored or released from the storage device to produce a desired amount of reactive power.   
     
     
         10 . The method of  claim 9 , wherein controlling further comprises controlling timing of switches within the DC bridge and the switched mode cycloconverter to control the amount of energy that is stored or released from the storage device to produce the desired amount of reactive power. 
     
     
         11 . The method of  claim 9 , wherein controlling further comprises determining the desired amount of reactive power using a reactive power control schedule comprising a schedule of reactive power to be generated as a function of one or more of an AC grid voltage, a bidirectional power converter output power, or a change in AC grid voltage. 
     
     
         12 . The method of  claim 11 , wherein the reactive power control schedule comprises a list of reactive power amounts and a corresponding time of day for generating each reactive power amount of the list of reactive power amounts. 
     
     
         13 . The method of  claim 11 , wherein controlling comprises using a maximum power point tracking controller for controlling real output power and using a reactive power controller for controlling reactive power output. 
     
     
         14 . The method of  claim 9 , wherein the switched mode cycloconverter is part of a bidirectional power converter, and wherein the bidirectional power converter is a static VAr compensator. 
     
     
         15 . The method of  claim 9 , wherein the switched mode cycloconverter is one of a single-phase cycloconverter or a three-phase cycloconverter. 
     
     
         16 . A system for controlling reactive power, comprising:
 a DC power source for generating DC power; and   a bidirectional power converter coupled to the DC power source for receiving the DC power and comprising:   a storage device for storing energy;   a DC bridge, coupled to the storage device, for producing a high-frequency AC signal;   a switched mode cycloconverter, coupled to the DC bridge, for converting the high-frequency AC signal to a low-frequency AC signal; and   a controller, coupled to the DC bridge and the switched mode cycloconverter, for controlling an amount of energy that is stored or released from the storage device to produce a desired amount of reactive power.   
     
     
         17 . The system of  claim 16 , wherein the controller controls timing of switches within the DC bridge and the switched mode cycloconverter to control the amount of energy that is stored or released from the storage device to produce the desired amount of reactive power. 
     
     
         18 . The system of  claim 16 , wherein the controller determines the desired amount of reactive power using a reactive power control schedule comprising a schedule of reactive power to be generated as a function of one or more of an AC grid voltage, a bidirectional power converter output power, or a change in AC grid voltage. 
     
     
         19 . The system of  claim 18 , wherein the reactive power control schedule comprises a list of reactive power amounts and a corresponding time of day for generating each reactive power amount of the list of reactive power amounts. 
     
     
         20 . The system of  claim 16 , wherein the DC power source comprises a battery or a solar panel.