Abb Schweiz Ag

Veerakumar Bose

Thomas Anthony Kendzia, Iii

Christopher Alan Belcastro

Harshang Shah

Xiaoqing Song

Yuzhi Zhang

Yu Du

Harish Suryanarayana

Liju Kallarackal

Hany Fawzy Kamel Habib

Hany Habib

Paul Thomas Yerly

In one aspect, a controller for managing electrical faults in a microgrid is provided. The microgrid includes electrical loads, electrical sources, and circuit protection devices that selectively couple the electrical loads and the electrical sources with each other. The controller comprises at least one processor configured to direct a grid tie switch to open to electrically isolate the microgrid from an electric grid, determine, in response to directing the grid tie switch to open, that an electrical fault exits in the microgrid, and determine whether a fault current of the electrical fault is less than a threshold value. The at least one processor is further configured to direct the grid tie switch to close to electrically connect the microgrid to the electric grid and increase the fault current above the threshold value in response to determining that the fault current is less than the threshold value.

Systems and a method for fault protection of selectively islanded microgrids

A transfer switch for hybrid switching between a first power source and a second power source, the transfer switch includes a first switch and a second switch, the first and second switch connecting a load to a first power source and a second power source, respectively. The first switch includes at least one first solid state switching device (SSSD) pair. The second switch includes at least one second SSSD pair. The at least one first SSSD pair includes a different type of switching devices relative to the type of switching devices of the at least one second SSSD pair. Moreover, a controller may be configured to selectively cycle the at least one first SSSD pair and the at least one second SSSD pair on and off to electrically couple one of the first power source and the second power source to the load.

Hybrid bridge transfer switch system and methods

Systems and methods for a transfer switch including a first switch device at a first leg between a first power source and an electrical load, and a second switch device at a second leg between a second power source and the electrical load and a first resistor circuit including a third switch device connected to the first leg. The third switch device switches between open and closed states in response to the state of the first switch device to limit back feed voltage generated as a result of leakage current when the first power source is inactive. The system may also include a second resistor circuit including a fourth switch device connected to the second leg. The fourth switch device switches between open and closed states in response to the state of the second switch device to limit back feed voltage as a result of leakage current when the second power source is inactive.

Active pre-load resistor

A method operable by a controller of a static transfer switch (STS) is provided. The STS includes first and second inputs selectively coupled with first and second power sources via first and second circuit breakers, respectively, an output coupled with a load, first and second bypass breakers selectively coupling the first and second inputs, respectively, with the output, at least one removable power stage module including first and second power stages configured to conduct electrical power when active, first and second contactors selectively coupling the first and second inputs with the first and second power stages, respectively, and a load switch selectively coupling the first and second power stages with the output. The method includes modifying an operating state of the first and second contactors and the first and second power stages to implement a bypass operation and an un-bypass operation of the STS in response to a trigger condition.

Static transfer switches with intelligent bypass and removable power stages

A system and a method for connecting electrical load(s) to a first power source and a second power source including a switching device and a controller. The switching device includes a first semiconductor device pair and a second semiconductor device pair. The controller configured to receive a first set of electronic signals corresponding to a condition of the first power source and the second power source, isolate the first power source or the second power source from the one or more loads by transmitting a first set of control signals to the switching device, receive a second set of electronic signals corresponding to the condition of the first power source and the second power source, and connect the first power source or the second power source to the one or more loads by transmitting a second set of control signals to the switching device.

Convertible transfer switch

A ground fault protection system includes a power switch including a source-side and a load-side. The power switch is structured to receive a load current from a power source at the source-side and selectively output the load current from the load-side to a load. A first voltage measuring device is structured to measure a first voltage of the source-side while the power switch is not conducting the load current. A second voltage measuring device is structured to measure a second voltage of the load-side while the power switch is not conducting the load current. A controller is structured to determine a source-side-to-ground voltage based on the first voltage, determine a load-side-to-ground voltage based on the second voltage, determine a ground fault is occurring, and determine a direction of the ground fault relative to the power switch.

Ground fault protection in a high resistance grounding system

A system for using one of two independent alternating power sources to power a load is provided. The system sets a flux match to a first value, wherein the flux match indicates a set range for switching between powering the load using a first power source and powering the load using a second power source. The system switches between powering the load using the first power source and powering the load using the second power source using the first flux match value. The system further obtains a first set of inrush current values associated with the switching. Based on the first set of inrush current values and a maximum inrush current threshold, the system adjusts the flux match to a second value and switches between powering the load using the first power source and powering the load using the second power source using the second flux match value.

Systems and methods for self-learning of transformer inrush characteristics to optimize transfer times in static transfer switch

Disclosed herein is a hybrid resonant capacitor circuit including a first capacitor configured to discharge resonant current to interrupt a load current to a switch in parallel with the hybrid resonant capacitor circuit, a second capacitor coupled in parallel with the first capacitor, wherein the second capacitor is configured to transfer energy stored in the second capacitor to the first capacitor after discharge of the resonant current from the first capacitor, and a current limiter coupled in series with the second capacitor. A static transfer switch including a thyristor switch and the hybrid resonant capacitor circuit is also disclosed herein, as is a method for facilitating multiple consecutive voltage source transfers between a first voltage source and a second voltage source powering a load, using the hybrid resonant capacitor circuit.

Rapid turn-off circuit in static transfer switch

A method of operating a static transfer switch is provided. The method includes monitoring a voltage waveform for each phase of first and second power sources, and calculating flux for each phase of the power sources. The method also includes determining (i) a first flux difference between the respective flux of the first phases of the first and second power sources, (ii) a second flux difference between the respective flux of the second phases of the first and second power sources, and (iii) a third flux difference between the respective flux of the third phases of the first and second power sources. The method further includes turning off a third solid-state switch to disconnect the third phase of the first power source from a load, in response to the controller determining that the third flux difference is greater the first and second flux differences.

Systems and methods of accelerating transfer in a static transfer switch

Systems, methods, techniques and apparatuses of ground fault protection are disclosed. One exemplary embodiment is a power switch being structured to receive a load current from a power source at a source-side and selectively output the load current from a load-side to a load; a first voltage measuring device structured to measure a first voltage of the source-side while the power switch is conducting the load current; a second voltage measuring device structured to measure a second voltage of the load-side while the first voltage measuring device is measuring the first voltage; and a controller structured to determine a source-side-to-ground voltage based on the first voltage, determine a load-side-to-ground voltage based on the second voltage, determine a ground fault is occurring, and determine a direction of the ground fault relative to the power switch by comparing the source-side-to-ground voltage and the load-side-to-ground voltage.

A static transfer switch is provided for supplying power to a load alternately from two different power sources. Switching between the two power sources may occur within a fraction of one electrical cycle. In response to sensing degraded performance in the power source supplying the load, a main circuit is turned off with a resonant turn off circuit. The resonant turn off circuit is shared between the main circuits of two different power sources such that the resonant turn off circuit is connected to the main circuit of whichever power source is currently supply power to the load.

Shared resonant turn off circuit

A static transfer switch is provided for supplying power to a load alternately from two different power sources. Switching between the two power sources may occur within a fraction of one electrical cycle. In response to sensing degraded performance in the power source supplying the load, resonant turn off circuits connected directly to the main switches of two phases of the power source are actuated to commutate the respective main switches. The main switch of the third phase is commutated with one or more of the resonant turn off circuits through the delta side of a transformer connected to the three phases of the power source.

Growing community of inventors

Richmond, VA, United States of America

Veerakumar Bose