Hybrid power plant for improved efficiency and dynamic performance

Abstract

A hybrid power plant is characterized by a substantially constant load on generators regardless of momentary swings in power load. Short changes in power load are accommodated by DC components such as capacitors, batteries, resistors, or a combination thereof. Resistors are used to consume power when loads in the power plant are generating excess power. Capacitors are used to store and deliver power when the loads in the power plant demand additional power. Reducing rapid changes in power load as seen by the generators allows the generators to operate at higher efficiencies and with reduced emissions. Additionally, power plants employing combinations of generators, loads, and energy storage devices have increased dynamic performance.

What is claimed is: 
     
         1 . An apparatus, comprising:
 an AC power source coupled to an AC bus;   a bidirectional AC-to-DC converter coupled to the AC bus and a DC bus;   a first AC load coupled to the AC bus; and   an active power compensation system coupled to the DC bus, wherein the active power compensation system comprises an energy storage device coupled to the DC bus through a switch.   
     
     
         2 . The apparatus of  claim 1 , further comprising a summation block on the AC bus coupled to the AC power source, the AC load, and the bidirectional AC-to-DC converter, wherein the active power compensation system is configured to maintain an approximately constant load on the AC power source through the summation block. 
     
     
         3 . The apparatus of  claim 1 , further comprising:
 a DC-to-AC converter coupled to the DC bus; and   a second AC load coupled to the DC bus through the DC-to-AC converter.   
     
     
         4 . The apparatus of  claim 3 , wherein the DC-to-AC converter is bidirectional to allow power regeneration of the motor to provide power to the DC bus. 
     
     
         5 . The apparatus of  claim 1 , wherein the switch comprises a DC-to-DC converter. 
     
     
         6 . The apparatus of  claim 1 , wherein the energy storage device comprises at least one of an ultracapacitor, a capacitor, a battery, and a fly wheel. 
     
     
         7 . A method, comprising:
 energizing an AC bus from an AC power source;   powering an AC load with the AC bus;   transferring energy from the AC bus to a DC bus through a bidirectional AC-to-DC converter; and   storing energy in a power storage device from the DC bus by transferring energy through a switch.   
     
     
         8 . The method of claim  11 , further comprising maintaining an approximately constant load on the AC power source by routing power between the AC power source, the AC load, and the power storage device through a summation block. 
     
     
         9 . The method of claim  11 , further comprising powering a second AC load from the DC bus through a DC-to-AC converter. 
     
     
         10 . The method of claim  13 , further comprising providing power to the DC bus from the second AC load through the DC-to-AC converter.