Residential static VAR compensator apparatus and method

Patent metadata

Field	Value
Publication number	US-10811879-B2
Application number	US-201715798675-A
Country	US
Kind code	B2
Filing date	Oct 31, 2017
Priority date	Oct 31, 2017
Publication date	Oct 20, 2020
Grant date	Oct 20, 2020

Abstract

A static volt-ampere reactive (VAR) compensator apparatus includes a capacitor electrically coupled between a phase conductor and a neutral conductor. The apparatus further includes a first switch electrically coupled between the phase conductor and an intermediate node. The apparatus also includes an inductor electrically coupled between the intermediate node and the neutral conductor in series with the first switch. The apparatus includes a second switch electrically coupled between the intermediate node and the neutral conductor in parallel with the inductor. The apparatus further includes a controller configured to transmit signals to the first switch and the second switch that cause the apparatus to modulate between a first state, in which the first switch is open and the second switch is closed, and a second state, in which the first switch is closed and the second switch is open.

First claim

What is claimed is:

1. A static volt-ampere reactive (VAR) compensator apparatus comprising:
a capacitor electrically coupled between a phase conductor and a neutral conductor;
a first switch electrically coupled between the phase conductor and an intermediate node, the first switch comprising a first sub-switch and a second sub-switch;
an inductor electrically coupled between the intermediate node and the neutral conductor in series with the first switch;
a second switch electrically coupled between the intermediate node and the neutral conductor in parallel with the inductor, the second switch comprising a third sub-switch and a fourth sub-switch; and
a controller configured to transmit signals to the first switch and the second switch that cause the apparatus to modulate between a first steady state, in which the first sub-switch and the second sub-switch are open and the third sub-switch and fourth sub-switch are closed, and a second steady state, in which the first sub-switch and the second sub-switch are closed and the third sub-switch and fourth sub-switch are open, wherein the apparatus passes between the first steady state and the second steady state according to a first set of intermediate states when a voltage at the phase conductor is positive, and wherein the apparatus passes between the first steady state and the second steady state according to a second set of intermediate states when the voltage at the phase conductor is negative.

2. The apparatus of claim 1 , wherein the phase conductor is configured to receive a single phase power signal therethrough.

3. The apparatus of claim 1 , wherein the apparatus passes between the first steady state and the second steady state according to the first set of intermediate states when a current through the inductor from the phase conductor to the neutral conductor is positive, and wherein the apparatus passes between the first steady state and the second steady state through the second set of transient states when the current through the inductor from the phase conductor to the neutral conductor is negative.

4. The apparatus of claim 1 , wherein the first switch is a bidirectional switch, wherein the first sub-switch and the second sub-switch are paired with respective diodes electrically coupled in an antiparallel configuration, wherein the second switch is a bidirectional switch, and wherein the third sub-switch and the fourth sub-switch are paired with additional respective diodes electrically coupled in an antiparallel configuration.

5. The apparatus of claim 1 , wherein the controller is configured to suspend the modulation between the first steady state and the second steady state when a voltage at the phase conductor is within a threshold voltage of zero.

6. The apparatus of claim 5 , wherein the controller is configured to return the apparatus to the first steady state before suspending the modulation between the first steady state and the second steady state.

7. The apparatus of claim 1 , wherein a duty cycle of the first switch and the second switch is adjustable to alter an effective inductance of the apparatus.

8. The apparatus of claim 1 , wherein a modulation frequency of the first switch and the second switch is between 3 kHz and 12 kHz.

9. A power distribution system comprising:
a feeder including a phase conductor and a neutral conductor; and
one or more static volt-ampere reactive (VAR) compensator apparatuses positioned between the feeder and one or more respective gateways, each static VAR compensator apparatus comprising:
a capacitor electrically coupled between the phase conductor and the neutral conductor;
a first switch electrically coupled between the phase conductor and an intermediate node;
an inductor electrically coupled between the intermediate node and the neutral conductor in series with the first switch;
a second switch electrically coupled between the intermediate node and the neutral conductor in parallel with the inductor; and
a controller configured to transmit signals to the first switch and the second switch that cause the VAR compensator apparatus to modulate between a first steady state, in which the first switch is open and the second switch is closed, and a second steady state, in which the first switch is closed and the second switch is open,

wherein each static VAR compensator apparatus is configured to measure load characteristics associated with the respective gateways and to determine whether to modulate between the first steady state and the second steady state based on a minimum power-point tracker algorithm.

10. The system of claim 9 , wherein the phase conductor is configured to receive a single phase power signal therethrough.

11. The system of claim 9 , wherein each VAR compensator apparatus passes between the first steady state and the second steady state through a first set of transient states when a voltage at the phase conductor is positive, and wherein the apparatus passes between the first steady state and the second steady state according to a second set of transient states when the voltage at the phase conductor is negative.

12. The system of claim 9 , wherein each VAR compensator apparatus passes between the first steady state and the second steady state through a first set of transient states when a current through the inductor from the phase conductor to the neutral conductor is positive, and wherein the apparatus passes between the first steady state and the second steady state through a second set of transient states when the current through the inductor from the phase conductor to the neutral conductor is negative.

13. The system of claim 9 , wherein the first switch is a bidirectional switch having a first switch-diode pair and a second switch-diode pair electrically coupled in an antiparallel configuration, and wherein the second switch is a bidirectional switch having a first switch-diode pair and a second switch-diode pair electrically coupled in an antiparallel configuration.

14. The system of claim 9 , wherein the controller is configured to suspend the modulation between the first steady state and the second steady state when a voltage at the phase conductor is within a threshold voltage of zero.

15. The system of claim 9 , wherein a modulation frequency of the first switch and the second switch is adjustable to alter an effective inductance of each individual apparatus.

16. The system of claim 9 , wherein the system does not include harmonic filter devices between the feeder and each of the respective gateways.

17. The system of claim 9 , further comprising at least one additional VAR compensator apparatus positioned between the feeder and at least one additional gateway.

18. A method comprising:
providing capacitance between a phase conductor and a neutral conductor;
providing a first switch electrically coupled between the phase conductor and an intermediate node, the first switch comprising a first sub-switch and a second sub-switch;
providing inductance between the intermediate node and the neutral conductor;
providing a second switch electrically coupled between the intermediate node and the neutral node, the second switch comprising a third sub-switch and a fourth sub-switch;
transmitting signals to the first switch and the second switch modulating the first switch and the second switch between a first steady state, in which the first sub-switch and the second sub-switch are open and the third sub-switch and the fourth sub-switch are closed, and a second steady state, in which the first sub-switch and the second su

Assignees

• Univ Boise State

Inventors

• Ahmed-Zaid Said
• Latif Muhammad Kamran

Classifications

• Y02B70/10

  Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes · CPC title

• G06Q50/06

  Energy or water supply · CPC title

• H02M5/293

  using semiconductor devices only · CPC title

• H02J3/185 Primary

  the reactive elements being purely inductive, e.g. superconductive magnetic energy storage [SMES] systems · CPC title

• G05F1/70

  Regulating power factor; Regulating reactive current or power · CPC title