US 5,798,633 AGranted

Battery energy storage power conditioning system

AssigneeGeneral Electric Company

InventorsEinar V. Larsen, Robert W. Delmerico

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Abstract

A method and apparatus for controlling a battery energy storage system of the type in which an inverter is coupled to convert direct current power from a DC source to a controlled frequency AC power suitable for supplementing utility power or for replacing utility power includes a control mechanism for operating the system and either a supplemental or replacement mode in parallel with a utility power system. The system favors frequency control over power control and maintains constant monitoring of frequency output with adjustment of power in response to any frequency shift of the inverter output. The system also includes apparatus for determining a power error signal based upon commanded power output in which the power error signal is applied as a phase shift control signal in the frequency control circuit for regulating the real component of power supplied by the inverter. In one form, the system is illustrated as multiple, parallel connected power control systems coupled to a common DC source for supplying a common AC output and each of the power control systems are regulated in response to the reactive component of power supplied therefrom so as to promote load sharing between the separate power control systems.

Claims15

Dependent claims

A control system for controlling a solid-state inverter coupling a direct current (DC) power source in parallel power transfer with a utility power system, each of the inverter and utility power system being adapted for supplying alternating current (AC) electric power to a load with a selected load voltage, the inverter including a plurality of solid-state, electronically controllable switches, each of the switches being responsive to electronic control signals for gating the switches into and out of conduction, the system comprising:

a gating logic circuit for generating the electronic control signals in response to a voltage command signal and a phase command signal, the voltage command signal establishing the conduction times of the controllable switches and the phase command signal establishing the output frequency and phase of the inverter output voltage;
a voltage regulator coupled for receiving a voltage error signal representative of any difference between the selected magnitude of load voltage and a measured magnitude of voltage representative of load voltage, the voltage regulator being responsive to the voltage error signal for generating the voltage command signal with a magnitude sufficient to minimize the voltage error signal;
a power regulator coupled for monitoring the frequency of the voltage from the inverter and comparing the frequency to a reference frequency for generating a power offset signal for maintaining the frequency of the voltage from the inverter at about the reference frequency, the power regulator further including:
a power processing circuit coupled for receiving the power offset signal, a power error signal representative of any difference between measured real component of power from the inverter and a desired power output of the inverter and for generating therefrom a phase shift signal for summation with a measured phase of the selected load voltage for regulating the real component of power supplied by the inverter.

1 more element

A method for controlling an inverter coupled for supplying power derived from a direct current source to an alternating current (AC) power system both during periods in which the power system also receives AC power from a fixed frequency AC utility system and during periods in which the fixed frequency AC utility system is disabled, the inverter including a plurality of pulse width modulated switching devices responsive to a corresponding plurality of gating signals for producing a simulated AC voltage output, the method comprising the steps of:

generating the gating signals in response to a voltage command signal and a phase command signal, the voltage command signal establishing the conduction times of the controllable switches and the phase command signal establishing an output frequency and phase of the inverter output voltage;
producing a voltage error signal representative of any difference between a desired magnitude of voltage from the inverter and a measured magnitude of voltage representative of load voltage;
generating from the voltage error signal a voltage command signal with a magnitude sufficient to minimize the voltage error signal;
monitoring the frequency of the inverter output voltage and comparing the frequency to a reference frequency for generating a phase offset signal for maintaining the frequency of the output voltage at about the reference frequency;
generating a power error signal representative of any difference between measured real power output of the inverter and a signal representative of desired power output of the inverter;
and
generating from the power error signal a phase shift signal for summation with the phase command signal for regulating the real component of power supplied by the inverter.

4 more elements

Dependencies are inferred from the claim text.

Facts

Application: 08/690,293Filed 26 Jul 1996
Granted: 25 Aug 1998
Term ends: Not estimatedThe source records don’t support an estimate.

Classification8 codes

H02J 3/38
Circuit arrangements for AC mains or AC distribution networks: arrangements for feeding a single network from two or more generators or sources in…
H02J 3/28
Circuit arrangements for AC mains or AC distribution networks: arrangements for balancing of the load in networks by storage of energy
H02J 3/46
Arrangements for feeding a single network from two or more generators or sources in parallel; Arrangements for feeding already energised…
H02J 9/062
With automatic change-over , e.g. UPS systems: for AC powered loads