Method for Intelligent Load Management in Off-Grid AC Systems

Abstract

The current disclosure provides methods and systems for intelligent load management in off-grid AC systems and provides methods and systems to control and prioritize loads, so that supply and demand can be balanced via an extremely robust and reliable system.

What is claimed is: 
     
         1 . An off-grid system comprising:
 at least one local power generator;   at least one battery;   at least one variable frequency inverter for establishing AC voltage and determining AC frequency;   a channel of communication formed via changing the AC voltage;   at least one converter that varies AC frequency as a function of available power generation capacity, wherein the varying AC frequency comprises information that is available throughout the system;   at least one energy load, wherein the at least one energy load is adjusted in response to the varying AC frequency to prioritize the at least one energy load to avoid system overloading; and   wherein the off-grid system does not include a separate communication channel.   
     
     
         2 . The off-grid system of  claim 1 , wherein an inverter frequency is controlled in the range of f min <f nom <f max , wherein f min  is the minimum frequency, f nom  is the nominal frequency and f max  is the maximum frequency. 
     
     
         3 . The off-grid system of  claim 1 , wherein a lower frequency indicates less power is available and total load is reduced. 
     
     
         4 . The off-grid system of  claim 1 , wherein a higher frequency indicates that extra power is available for the off-grid system. 
     
     
         5 . The off-grid system of  claim 1 , further comprising trip points for load disconnect. 
     
     
         6 . The off-grid system of  claim 5 , wherein the load disconnect activates when the AC frequency falls below a preset value to prioritize at least one load. 
     
     
         7 . The off-grid system of  claim 1 , comprising at least two loads wherein the at least two loads are listed in order of decreasing priority, wherein a lowest priority load will be shut off when the AC frequency falls below a preset value. 
     
     
         8 . The off-grid system of  claim 1 , wherein the at least one battery is in a charge mode when the AC frequency is above a preset value and the at least one battery supplies power to the at least one load when the AC frequency is below the preset value. 
     
     
         9 . The off-grid system of  claim 8 , wherein the preset value comprises a frequency range with a high frequency and a low frequency point defined to condition battery operation. 
     
     
         10 . A method for managing and prioritizing loads based on system status comprising:
 establishing AC voltage and determining AC frequency via a local inverter;   creating a channel of communication via changing AC voltage frequency;   varying AC frequency, via a converter, as a function of available power generation capacity, wherein the varying AC frequency comprises information that is available throughout the system; and   adjusting at least one intelligent load based on the varying AC frequency to prioritize the intelligent load and avoid system overloading, wherein the AC frequency controls source power in steps from a negative value when frequency is low to full power delivered to the at least one intelligent load when signaling frequency is high.   
     
     
         11 . The method of  claim 10 , wherein the method does not employ a separate communication channel but instead the AC frequency communicates to an entirety of the system. 
     
     
         12 . The method of  claim 10 , further comprising controlling an inverter frequency in the range of f min <f nom <f max , wherein f min  is the minimum frequency, f nom  is the nominal frequency and f max  is the maximum frequency. 
     
     
         13 . The method of  claim 10 , further comprising reducing total load when a lower frequency indicates less power is available. 
     
     
         14 . The method of  claim 10 , further comprising a higher frequency indicating that extra power is available for the system. 
     
     
         15 . The method of  claim 10 , further comprising employing trip points for load disconnect. 
     
     
         16 . The method of  claim 15 , further comprising activating the load disconnect when the AC frequency falls below a preset value to prioritize at least one load. 
     
     
         17 . The method of  claim 10 , further comprising listing at least two loads in order of decreasing priority and shutting off a lowest priority load when the AC frequency falls below a preset value. 
     
     
         18 . The method of  claim 10 , further comprising placing at least one battery in a charge mode when the AC frequency is above a preset value and supplying power from the at least one battery to the at least one intelligent load when the AC frequency is below the preset value. 
     
     
         19 . The method of  claim 18 , further comprising the preset value comprising a frequency range with a high frequency and a low frequency point defined to condition battery operation.