Transient power stabilization device with active and reactive power control

• US 10,574,055 B2
• Filed: 12/22/2015
• Issued: 02/25/2020
• Est. Priority Date: 12/30/2014
• Status: Active Grant

• Current Assignee: FlexGen Power Systems Inc.
• Original Assignee: FlexGen Power Systems Inc.
• Inventors: Yang, Mengbin, Taimela, Pasi, Olivo, Tony, Johnson, Jr., Robert William, Balakrishnan, Gopalakrishnan
• Primary Examiner(s): Barnie, Rexford N
• Assistant Examiner(s): Mourad, Rasem
• Application Number:
  US15/539,772
• Publication Number:
  US 20180013288A1
• Time in Patent Office: 1,526 Days
• CPC Class Codes: H02J 2300/10 The dispersed energy generation being of fossil origin, e.g. diesel generators
• 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 3/1842 wherein at least one reactive element is actively controlled by a bridge converter, e.g. active filters
• CPC Class Codes: H02J 3/241 The oscillation concerning frequency
• CPC Class Codes: H02J 3/28 Arrangements for balancing of the load in a network by storage of energy
• CPC Class Codes: H02J 3/32 using batteries with converting means
• CPC Class Codes: H02J 3/381 Dispersed generators
• CPC Class Codes: H02J 3/48 Controlling the sharing of the in-phase component
• CPC Class Codes: H02J 3/50 Controlling the sharing of the out-of-phase component
• CPC Class Codes: Y02E 40/20 Active power filtering [APF]

Abstract

A system includes a converter configured to be coupled between an energy storage unit and a grid and a control circuit configured to detect frequency and voltage variations of the grid and to responsively cause the converter to transfer power and reactive components to and/or from the grid. The control circuit may implement a power control loop having an inner frequency control loop and a reactive component control loop having an inner voltage control loop. The control circuit may provide feedforward from the inner frequency control loop to the inner voltage control loop to inhibit reactive component transfer in response to a voltage variation deviation of the grid due to a power transfer between the energy storage unit and the grid.

Claims

1. A system comprising:

a converter configured to be coupled between an energy storage unit and a grid;

a converter controller configured to control the converter responsive to a real power command and a reactive power command that respectively cause the converter to transfer a real power component and a reactive power component; and

a control circuit configured to detect frequency and voltage variations of the grid and to responsively generate the real power command and the reactive power command, wherein the control circuit implements;

a real power control loop configured to generate the real power command responsive to a frequency of the grid and a real power reference; and

a reactive power control loop configured to generate the reactive power command responsive to a voltage of the grid, a reactive power reference and a feedforward of the real power command.

2. The system of claim 1, wherein the real power control loop produces the real power command responsive to a measured frequency and wherein the reactive power control loop is coupled to the real power control loop by a crossover gain that receives the real power command and provides the feedforward.

3. The system of claim 1, wherein the feedforward of the real power command inhibits reactive component transfer between the converter and the grid in response to a voltage variation deviation of the grid due to a change in real power demand on the grid.

4. The system of claim 1, wherein the real power and reactive power loops are configured to drive real power and reactive power transfers by the converter to substantially zero when a frequency and a voltage of the grid meet predetermined criteria.

5. The system of claim 1, wherein the control circuit is configured to provide real power flow from the grid to the energy storage unit by varying a power reference provided to the real power control loop when the frequency and the voltage of the grid meet the predetermined criteria.

6. The system of claim 1, wherein the control circuit is configured to cause the converter to maintain a frequency and a voltage of the grid within ranges that prevent shutdown of an engine/generator set driving the grid in response to a startup of a motor coupled to the grid.

7. The system of claim 1, wherein the control circuit is configured to detect transient frequency and voltage variations of the grid associated with a startup of a motor load on the grid and to responsively cause the converter to transfer real power and reactive power until the voltage and the frequency of the grid reach a predetermined state.

8. A method comprising:

a real power control loop generating a real power command responsive to a frequency of a grid and a real power reference;

a reactive power control loop generating a reactive power command responsive to a voltage of the grid, a reactive power reference and a feedforward of the real power command from the real power control loop; and

a converter transferring real power and reactive power between an energy storage device and the grid responsive to the real power command and the reactive power command respectively.

9. The method of claim 8, wherein the real power control loop produces the real power command responsive to a measured frequency and wherein the reactive power control loop is coupled to the real power control loop by, a crossover gain that receives the real power command and responsively provides the feedforward.

10. The method of claim 8, wherein the feedforward of the real power command inhibits reactive component transfer between the converter and the grid in response to a voltage variation deviation of the grid due to an increase in real power demand on the grid.