System and method for regulation of voltage on an electrical network

Patent metadata

Field	Value
Publication number	US-9600004-B2
Application number	US-201514617065-A
Country	US
Kind code	B2
Filing date	Feb 9, 2015
Priority date	Feb 9, 2015
Publication date	Mar 21, 2017
Grant date	Mar 21, 2017

Abstract

An electric power system including an on-load tap changing (OLTC) transformer is provided. The OLTC transformer includes a primary winding and a secondary winding. A portion of the at least one primary winding and at least one of the secondary windings are inductively coupled to each other. Further, the electric power system includes at least one on-load tap changer coupled to the at least one primary winding or the at least one secondary winding of the OLTC transformer. The on-load tap changer is configured to regulate the portion of the at least one primary winding or the at least one secondary winding that are inductively coupled to each other. Furthermore, the system includes at least one controller coupled to the on-load tap changer. The controller is configured to determine a permissible voltage range defined by a bandwidth around a voltage set-point at the at least one on-load tap changer, where the bandwidth is a function of one or more electrical network states.

First claim

What is claimed is:

1. An electric power system comprising:
an on-load tap changing (OLTC) transformer comprising at least one primary winding and at least one secondary winding, wherein a portion of the at least one primary winding and the at least one secondary winding are inductively coupled to each other;
at least one on-load tap changer coupled to the at least one primary winding or the at least one secondary winding, wherein the at least one on-load tap changer is selectively configured to regulate the portion of the at least one primary winding or the at least one secondary winding that are inductively coupled to each other;
at least one controller coupled to the at least one on-load tap changer, wherein the at least one controller is configured to determine a permissible voltage range defined by a bandwidth around a voltage set-point at the at least one on-load tap changer, wherein the bandwidth is variable and is a function of one or more electrical network states;
wherein the one or more electrical network states are indicated by current or power flow measurements at the at least one tap changer; and
wherein the at least one controller is further configured to determine a maximum possible voltage rise and a maximum possible voltage drop in the electrical network for each of the current or power flow measurements at the tap changer based on a plurality of factors, and wherein the plurality of factors comprise line resistances, line lengths, power ratings of at least one load, power ratings of at least one power source, distances between the tap changer and at least one load, and distances between the tap changer and at least one power source.

2. The electric power system in accordance with claim 1 , wherein the controller is further configured to:
generate an upper bandwidth limit of the permissible voltage range that is a function of one or more electrical network states; and
generate a lower bandwidth limit of the permissible voltage range that is a function of one or more electrical network states.

3. The electric power system in accordance with claim 1 , wherein the upper and lower bandwidth limits of the permissible voltage range that are a function of one or more electrical network states are based on a:
maximum possible voltage rise for each of the current or power flow measurements at the at least one tap changer; and
minimum possible voltage drop for each of the current or power flow measurements at the at least one tap changer.

4. The electric power system in accordance with claim 1 , wherein a voltage set-point for the OLTC transformer is variable dependent on the one or more electrical network states.

5. The electric power system in accordance with claim 1 further comprising at least one memory device coupled to the at least one controller, wherein the at least one memory device is configured to store the bandwidth at the tap changer as a function of the one or more electrical network states.

6. The electric power system in accordance with claim 1 , wherein a voltage set-point for the OLTC transformer is constant.

7. A method of regulating a voltage at an on-load tap changer, the on-load tap changer being coupled to at least one primary winding or at least one secondary winding of an OLTC transformer, the on-load tap changer being configured to regulate an inductive coupling between the at least one primary winding and the at least one secondary winding, wherein the on-load tap changer is communicably coupled to a controller, the method comprising:
determining a bandwidth around a voltage set-point at the on-load tap changer that is variable and is a function of one or more electrical network states;
measuring the voltage at the on-load tap changer in the electrical network;
generating a command for at least one tap change when the measured voltage falls out of bandwidth that is a function of one or more electrical network states defined for the electrical network such that a measured voltage after the at least one tap change is within the bandwidth, wherein the one or more electrical network states are indicated by current or power flow measurements at the at least one tap changer; and
determining a maximum possible voltage rise and a maximum possible voltage drop in the electrical network for each of the current or power flow measurements at the tap changer based on a plurality of factors, and wherein the plurality of factors comprise line resistances, line lengths, power ratings of at least one load, power ratings of at least one power source, distances between the tap changer and at least one load, and distances between the tap changer and at least one power source.

8. The method in accordance with claim 7 , further comprising:
generating an upper bandwidth limit of the permissible voltage range that is a function of one or more electrical network states; and
generating a lower bandwidth limit of the permissible voltage range that is a function of one or more electrical network states.

9. The method in accordance with claim 8 , wherein generating the upper bandwidth limit and the lower bandwidth limit of the permissible range further comprises:
determining the maximum possible voltage rise for each of the current or power flow measurements at the at least one tap changer; and
determining the minimum possible voltage drop for each of the current or power flow measurements at the at least one tap changer.

10. The method in accordance with claim 8 , wherein the voltage set-point for the OLTC transformer is variable dependent on the one or more electrical network states.

11. The method in accordance with claim 7 , further comprising storing the bandwidth for the electrical network as a function of the one or more electrical network states.

12. The method in accordance with claim 7 , wherein the voltage set-point for the OLTC transformer is constant.

Assignees

• Gen Electric

Inventors

• Baerthlein Eva-Maria
• Hartung Marianne Luise Susanne
• Panosyan Ara

Classifications

• H02J3/12

  Arrangements for adjusting voltage in AC networks by changing a characteristic of the network load · CPC title

• H02P13/06

  by tap-changing; by rearranging interconnections of windings · CPC title

• Y04S10/123

  the energy generation units being or involving renewable energy sources · CPC title

• G05F1/14

  using tap transformers or tap changing inductors as final control devices · CPC title

• H01F29/04

  having provision for tap-changing without interrupting the load current · CPC title