Enhancing power system voltage stability using grid energy storage for voltage support

• US 9,866,029 B2
• Filed: 11/04/2015
• Issued: 01/09/2018
• Est. Priority Date: 11/04/2014
• Status: Active Grant

• Current Assignee: NEC Corporation
• Original Assignee: NEC Corporation
• Inventors: Shi, Di, Sharma, Ratnesh
• Primary Examiner(s): Kim, Jung
• Application Number:
  US14/932,609
• Publication Number:
  US 20160126739A1
• Time in Patent Office: 797 Days
• CPC Class Codes: G01R 31/367 Software therefor, e.g. for battery testing using modelling or look-up tables
• CPC Class Codes: H02J 2203/20 Simulating, e g planning, reliability check, modelling or computer assisted design [CAD]
• CPC Class Codes: H02J 2300/20 The dispersed energy generation being of renewable origin
• CPC Class Codes: H02J 2300/24 of photovoltaic origin
• 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: Y02E 10/56 Power conversion systems, e.g. maximum power point trackers
• CPC Class Codes: Y02E 60/00 Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
• CPC Class Codes: Y02E 70/30 Systems combining energy storage with energy generation of non-fossil origin
• CPC Class Codes: Y04S 40/20 Information technology specific aspects, e.g. CAD, simulation, modelling, system security

Abstract

Systems and methods for voltage control in an energy distribution system (EDS), including measuring voltage and current at a node in the EDS where a Grid Energy Storage (GES) device is located. A simplified equivalent of the EDS is generated by identifying parameters for the equivalent and calculating phasors corresponding to the measured voltage and current. At least one of a voltage stability index or a voltage sensitivity factor of the EDS is calculated using the equivalent, and at least one of charging or discharging of the EDS is adjusted based on at least one of the voltage stability index or the voltage sensitivity factor to regulate and stabilize voltage of the EDS.

Claims

1. A method for voltage control in an energy distribution system (EDS), comprising:

measuring voltage and current at a node in the EDS where a Grid Energy Storage (GES) device is located;

generating a simplified equivalent of the EDS by identifying parameters for the equivalent and calculating phasors corresponding to the measured voltage and current, the phasors being calculated using Discrete Fourier Transform by transforming a sequence of N real numbers into an N-periodic sequence of complex numbers;

determining at least one of a voltage stability index or a voltage sensitivity factor of the EDS using the equivalent; and

adjusting at least one of charging or discharging of the EDS based on at least one of the voltage stability index or the voltage sensitivity factor to regulate and stabilize voltage of the EDS.

2. The method of claim 1, wherein the equivalent is a Thevenin equivalent.

3. The method of claim 1, wherein the voltage stability index is determined after detection of voltage instability in the EDS.

4. The method of claim 1, wherein the voltage sensitivity factor is determined after detection of a voltage violation in the EDS.

5. The method of claim 1, wherein the parameters for the equivalent continually change as EDS operating conditions vary.

6. The method of claim 1, wherein the parameters for the equivalent are identified using a Kalman filter.

7. The method of claim 1, wherein the parameters for the equivalent are identified using recursive least squares.

8. The method of claim 1, wherein the determining of the voltage stability index includes calculating a maximum power transferrable through a particular node.

9. The method of claim 1, wherein the voltage instability is detected when a magnitude of apparent impedance is equal to or smaller than the magnitude of Thevenin impedance.

10. A system for voltage control in an energy distribution system (EDS), comprising:

a measurement device for measuring voltage and current at a node in the EDS where a Grid Energy Storage (GES) device is located;

a processor configured to generate a simplified equivalent of the EDS by identifying parameters for the equivalent and calculating phasors corresponding to the measured voltage and current, wherein at least one of a voltage stability index or a voltage sensitivity factor are determined based on the equivalent, the phasors being calculated using Discrete Fourier Transform by transforming a sequence of N real numbers into an N-periodic sequence of complex numbers; and

a controller configured to adjust at least one of charging or discharging of the EDS based on at least one of the voltage stability index or the voltage sensitivity factor to regulate and stabilize voltage of the EDS.

11. The system of claim 10, wherein the equivalent is a Thevenin equivalent.

12. The system of claim 10, wherein the voltage stability index is determined after detection of voltage instability in the EDS.

13. The system of claim 10, wherein the voltage sensitivity factor is determined after detection of a voltage violation in the EDS.

14. The system of claim 10, wherein the parameters for the equivalent continually change as EDS operating conditions vary.

15. The system of claim 10, wherein the parameters for the equivalent are identified using a Kalman filter.

16. The system of claim 10, wherein the parameters for the equivalent are identified using recursive least squares.

17. The system of claim 10, wherein the determining of the voltage stability index includes calculating a maximum power transferrable through a particular node.

18. A computer-readable storage medium including a computer-readable program, wherein the computer-readable program when executed on a computer causes the computer to perform the steps of:

measuring voltage and current at a node in an Energy Distribution System (EDS) where a Grid Energy Storage (GES) device is located;

generating a simplified equivalent of the EDS by identifying parameters for the equivalent and calculating phasors corresponding to the measured voltage and current, the phasors being calculated using Discrete Fourier Transform by transforming a sequence of N real numbers into an N-periodic sequence of complex numbers;

determining at least one of a voltage stability index or a voltage sensitivity factor of the EDS using the equivalent; and

adjusting at least one of charging or discharging of the EDS based on at least one of the voltage stability index or the voltage sensitivity factor to regulate and stabilize voltage of the EDS.