Controlled electrical energy storage apparatus for utility grids
First Claim
1. A controlled electrical energy storage apparatus for selectively storing electrical energy from an AC electric power grid and for selectively releasing said electrical energy back to the AC electric power grid, said AC electric power grid having a plurality of phase lines, said controlled electrical energy storage apparatus comprising:
- a DC energy storage means for storing electrical energy;
a converter coupled between the DC energy storage means and the AC electric power grid for regulating the instantaneous current flow therebetween; and
a power flow control unit for controlling the direction and amount of real power flow through the converter by pulse width modulation of the converter to control the instantaneous current flow therethrough.
5 Assignments
0 Petitions
Accused Products
Abstract
A controlled electrical energy storage apparatus for selectively storing electrical energy from an electrical grid, and selectively releasing the electric energy back into the grid. The apparatus includes a converter coupled to the grid, and a DC energy storage device coupled to the converter. The converter includes a switching circuit having a plurality of high speed electrical switches arranged in pairs. Each switch pair is coupled between one of the phase lines of the AC utility grid and the DC energy storage device. The power flow control unit supplies a power flow control waveform to the switch pairs. The power flow control waveform includes a real waveform for control of real power and an imaginary waveform for control of reactive power independently of the real power. By pulse-width modulating the switches at a high frequency, the converter controls instantaneous currents flowing through each of the phase lines for precise control of the real and reactive power.
136 Citations
23 Claims
-
1. A controlled electrical energy storage apparatus for selectively storing electrical energy from an AC electric power grid and for selectively releasing said electrical energy back to the AC electric power grid, said AC electric power grid having a plurality of phase lines, said controlled electrical energy storage apparatus comprising:
-
a DC energy storage means for storing electrical energy; a converter coupled between the DC energy storage means and the AC electric power grid for regulating the instantaneous current flow therebetween; and a power flow control unit for controlling the direction and amount of real power flow through the converter by pulse width modulation of the converter to control the instantaneous current flow therethrough. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
-
-
10. A controlled electrical energy storage apparatus for selectively storing electrical energy from an AC electric power grid, selectively releasing said electrical energy back to the AC electric power grid, and supplying a selectable number of VARs of reactive power to the AC electric power grid, said AC electric power grid having a plurality of phase lines, said controlled electrical energy storage apparatus comprising:
-
a converter including a plurality of switch pairs for regulating the instantaneous current in each of said plurality of phase lines; a DC energy storage device coupled to each of said switch pairs; and a power flow control unit for controlling the switch pairs by pulse-width modulation of the instantaneous current flow through the converter to provide a real and reactive power flow, including; a power flow waveform generator for forming a power flow control waveform having a real component and an imaginary component, a real power control means for selecting a real power flow in direction and amount, and controlling the real component of the power flow control waveform, and a reactive power control means for selecting a reactive power amount and controlling the imaginary component of the power flow control waveform to supply said reactive power amount to the utility grid. - View Dependent Claims (11, 12, 13, 14, 15, 16)
-
-
17. A method for generating a power flow control waveform to control bidirectional power flow between an AC utility grid and a DC energy storage device, said AC utility grid supplying a reference voltage waveform from each phase line, said power flow control waveform being provided to a converter connected between the DC energy storage device and the AC utility grid, said power flow waveform generation method comprising, for each phase, the steps of:
-
(a) applying the reference waveform to a provide a real waveform; (b) multiplying the reference waveform by a real multiplier to provide a multiplied real waveform indicative of a direction and amount of real power flow; (c) applying the reference waveform to a provide an imaginary waveform rotated by 90°
from the reference waveform;(d) multiplying said imaginary waveforms by a VAR multiplier to provide a multiplied imaginary waveform, wherein the VAR multiplier has a value that is indicative of the number of VARs to be supplied to the utility grid; and (e) adding the results of said steps (b) and (d) so that the multiplied imaginary waveform is added to the multiplied real waveform to provide a power flow control waveform; and (f) controlling the instantaneous current by pulse width modulation to approximate the power flow control waveform. - View Dependent Claims (18, 19, 20)
-
-
21. A method for bidirectionally controlling a flow of real power in a converter between an AC utility grid and a DC energy storage device, comprising the steps of:
-
selecting a command real power flow in direction and amount; sensing a sensed parameter indicative of an actual real power flow; and controlling, responsive to said sensed parameter and said command real power flow, an instantaneous current flow through the converter by pulse-width modulation to provide said command real power flow. - View Dependent Claims (22, 23)
-
Specification