Medium voltage direct current power collection systems and methods

Patent metadata

Field	Value
Publication number	US-10348093-B2
Application number	US-201615378679-A
Country	US
Kind code	B2
Filing date	Dec 14, 2016
Priority date	Dec 14, 2016
Publication date	Jul 9, 2019
Grant date	Jul 9, 2019

Abstract

Unique systems, methods, techniques and apparatuses of a power collection system are disclosed herein. One exemplary embodiment is an MVDC collection system coupled to a utility grid including a collection bus, a plurality of branches coupled to the collection bus, and a branch controller. Each of the plurality of branches include a semiconductor switch coupled to the collection bus, and a DC/DC converter coupled to the semiconductor switch and an LVDC power source. The branch controller configured to determine a fault condition is occurring within the MVDC collection system, determine the location of the fault condition, and isolate the fault condition using at least one of the semiconductor switches and the DC/DC converters.

First claim

What is claimed is:

1. A medium voltage direct current (MVDC) power collection system comprising:
a power collection bus; and
a branch comprising:
a collection line coupled to the power collection bus by a first protective device including a first semiconductor switch coupled in parallel with a first surge arrester; and
a power converter coupled to the collection line by a second protective device including a second semiconductor switch coupled in parallel with a second surge arrester, and structured to receive low voltage direct current (LVDC) power from an LVDC power source, convert the received LVDC power to MVDC power, and output the MVDC power to the collection line; and

a collection system controller configured to determine if a first fault condition is occurring at the power converter or the LVDC power source and in response to open the second protective device to isolate the LVDC power source and the power converter from the collection line, and to determine if a second fault condition is occurring at the collection line and in response open the first protective device to isolate the collection line from the power collection bus.

2. The system of claim 1 comprising a second branch comprising:
a second collection line coupled to the power collection bus by a third protective device including a third semiconductor switch coupled in parallel with a third surge arrester; and
a second power converter coupled to the second collection line by a fourth protective device including a fourth semiconductor switch coupled in parallel with a fourth surge arrester, and structured to receive low voltage direct current (LVDC) power from an second LVDC power source, convert the received LVDC power to MVDC power, and output the MVDC power to the second collection line,
wherein the collection system controller configured to determine if a third fault condition is occurring at the power collection bus and in response open the first protective device to isolate the collection line and the second collection line from the power collection bus.

3. The system of claim 1 wherein the power converter includes a plurality of DC/DC converters, each DC/DC converter including an output, wherein the outputs of the DC/DC converters are coupled in series.

4. The system of claim 1 wherein the DC power source for each branch includes a solar panel array.

5. The system of claim 4 wherein the power converter of each branch is operated so as to optimize the power output of each solar panel array using maximum power point tracking.

6. An MVDC collection system coupled to a utility grid including:
a collection bus;
a plurality of branches coupled to the collection bus, each branch including:
a semiconductor switch coupled in parallel with a surge arrester and coupled in series to the collection bus, and
a DC/DC converter coupled to the semiconductor switch and an LVDC power source; and
a branch controller configured to determine a fault condition is occurring within the MVDC collection system, determine the location of the fault condition, and isolate the fault condition using at least one of the semiconductor switches and the DC/DC converter;

wherein the DC/DC converter for at least one of the branches includes an inverter, a transformer, and a diode rectifier, and the DC/DC converter includes an AC circuit breaker coupled between the inverter and the diode rectifier; and
wherein the branch controller is configured to open the AC circuit breaker in response to determining a fault condition is occurring within the MVDC collection system.

7. The system of claim 6 comprising a DC/AC converter coupled to the collection bus structured to receive MVDC power from the collection bus and convert the MVDC power to AC power, and a transformer coupled between the AC/DC converter and a utility grid, the transformer structured to receive the AC power, step up the voltage of the AC power, and output the AC power with stepped up voltage to the utility grid.

8. The system of claim 7 comprising an AC circuit breaker coupled between the DC/AC converter and the utility grid, wherein the branch controller is coupled to the AC circuit breaker and configured to determine a fault condition is occurring within the collection bus and to open the semiconductor switches of each branch and the AC circuit breaker in response to determining a fault condition is occurring within the collection bus.

9. The system of claim 6 , wherein medium voltage includes a range from 10 kV to 50 kV.

10. The system of claim 6 wherein at least one semiconductor switch includes an integrated gate commutated thyristors (IGCTs) coupled in parallel with a surge arrester.

11. The system of claim 6 wherein a fault condition includes one of a DC power source malfunction, a short circuit fault or a high impedance fault within one of the plurality of branches, or a short circuit fault or a high impedance fault within the collection bus.

12. The system of claim 6 wherein at least one of the DC/DC converters includes a wide bandgap switching device.

13. A method for operating an MVDC collection system comprising:
coupling a plurality of DC power sources to a plurality of power converters;
coupling a plurality of collection lines to a power collection bus by a respective plurality of first protective devices each including a first semiconductor switch coupled in parallel with a first surge arrester;
coupling each of the plurality of power converters to a respective one of the plurality of collection lines by a respective plurality of second protection devices each including a second semiconductor switch and a second surge arrester coupled in parallel to the second semiconductor switch;
operating each power converter so as to receive LVDC power from one of the plurality of DC power sources, converter the LVDC power to MVDC power, and output MVDC power to the power collection bus;
determining if a first fault condition is occurring at one of the plurality of DC power sources or one of the plurality of power converters and in response opening one of the plurality of second protective devices corresponding to the one of the plurality of DC power sources or the one of the plurality of power converters at which the first fault condition is occurring; and
determining if a second fault condition is occurring at one of the plurality of collection lines and in response opening one of the plurality of first protective device to isolate the one of the collection lines at which the second fault condition is occurring from the power collection bus.

14. The method of claim 13 comprising determining if a third fault condition is occurring at the power collection bus and in response opening each of the plurality of first protective devices to isolate each of the plurality of collection lines from the power collection bus.

Assignees

• Abb Schweiz Ag

Inventors

• Suryanarayana Harish
• Kim Hongrae
• Ahmed Sara
• Steimer Peter
• Maibach Philippe
• Krattiger Hans
• Alvarez Silverio
• Casini Paolo
• Pan Jiuping

Classifications

• H02J2101/24

  Photovoltaics · CPC title

• H02J3/383 Primary

  Electricity · mapped topic

• Y02E10/563

  Cross-Sectional Technologies · mapped topic

• H02H7/268 Primary

  for DC systems · CPC title

• H02J3/381

  Dispersed generators · CPC title