Method for controlling power flow between an electrochemical cell and a power grid

• US 4,251,736 A
• Filed: 07/23/1979
• Issued: 02/17/1981
• Est. Priority Date: 07/23/1979
• Status: Expired due to Term

• Current Assignee: United Technologies Corporation (Raytheon Technologies Corporation d/b/a RTX)
• Original Assignee: United Technologies Corporation (Raytheon Technologies Corporation d/b/a RTX)
• Inventors: Coleman, Allen K.
• Primary Examiner(s): Griffin, Donald A.
• Assistant Examiner(s): Dwyer, James L.
• Application Number:
  US06/059,725
• Time in Patent Office: 575 Days
• Field of Search: 307/87, 307/44, 307/45, 307/46, 307/, 307/48, 307/66, 307/72, 363/96, 363/97, 363/95
• US Class Current: 307/46
• CPC Class Codes: H02J 3/18 Arrangements for adjusting, eliminating or compensating reactive power in networks for adjustment of voltage H02J3/16
• CPC Class Codes: H02J 3/32 using batteries with converting means
• CPC Class Codes: H02M 7/48 using discharge tubes with control electrode or semiconductor devices with control electrode
• CPC Class Codes: Y02E 40/30 Reactive power compensation

Abstract

A method for controlling a force-commutated inverter coupled between an electrochemical cell and a power grid for adjusting the magnitude and direction of the electrical energy flowing therebetween. Both the real power component and the reactive power component of AC electrical energy flow can be independently varied through the switching waveform presented to the intermediately coupled inverter. A var error signal is derived from a comparison of a var command signal with a signal proportional to the actual reactive power circulating between the inverter and the power grid. This signal is presented to a voltage controller which essentially varies only the effective magnitude of the fundamental voltage waveform out of the inverter, thereby leaving the real power component substantially unaffected. In a similar manner, a power error signal is derived by a comparison of a power command signal with a signal proportional to the actual real power flowing between the electrochemical cell and the power grid. This signal is presented to a phase controller which varies only the phase of the fundamental component of the voltage waveform out of the inverter relative to that of the power grid and changes only the real power in proportion thereto, thus leaving the reactive power component substantially unaffected.

Claims

1. A method for adjusting the magnitude and direction of electrical power flowing from an electrochemical cell through an inverter to a power grid, or the like, comprising:

providing a reactive power command signal and a real power command signal, each of which is respectively proportional to the desired reactive power and real power energy flow between said electrochemical cell and said utility;

comparing said reactive power command signal and said real power command signal with a sensed signal which is proportional to the actual reactive power and real power components of energy flow, respectively, between said electrochemical cell and said utility to derive a reactive power error signal and a real power error signal;

comparing said reactive power error signal with the difference between the voltage of said electrochemical cell and said power grid voltage to form a voltage control signal for varying the amplitude of said fundamental signal waveform out of said inverter;

comparing said real power error command signal with a signal proportional to the phase of said fundamental signal waveform supplied to said inverter to form a phase control signal for varying the phase difference between the inverter fundamental signal waveform and that of said power grid waveform; and

adjusting the phase of the switching points of a switching waveform pattern in the inverter in response to the voltage control signal and the phase control signal.

2. A method according to claim 1, wherein said reactive power command signal and said real power command signal are independently adjustable so that the reactive power component and real power component of electrical energy flow can be separately controlled.