Hybrid circuit breaker

Abstract

Embodiments of the present disclosure relate to hybrid circuit breakers. In one aspect, a hybrid circuit protection device for current limiting a fault current between a source and a load during a fault is provided. The hybrid circuit protection device includes an input configured to be coupled to the source, an output configured to be coupled to the load, a circuit configured to couple the source to the load, a main switch configured to selectively couple the input to the output, a switch network coupled in parallel with the main switch, and a controller. The controller is configured to determine that the main switch has opened in response to the fault current, wherein the fault current has an initial value, and activate the switch network to current limit the fault current to be less than the initial value during the fault.

Description

[0001] Cross-reference to related applications

[0002] This invention was carried out with government support under contract number DE-AC02-06CH11357 granted by the Department of Energy. The government holds certain rights in this invention. Background Technology

[0003] The field of this disclosure relates to circuit breakers, and more specifically to hybrid circuit breakers including fault current limiters. Technical Field

[0004] A circuit breaker is a device implemented in a circuit path to protect downstream loads on a branch circuit during a fault. During a fault condition at a downstream load, the circuit breaker is designed to trip and disconnect the branch fed by the circuit breaker, thus de-energizing it. However, de-energizing a branch may also de-energize other loads on that branch, which is particularly undesirable in direct current (DC) distribution systems.

[0005] Therefore, it is desirable to improve the operation and performance of circuit breakers, and more specifically, to improve the operation and performance of circuit breakers used in DC power distribution systems. Summary of the Invention

[0006] In one aspect, a hybrid circuit protection device is provided for current limiting a fault current between a source and a load during a fault. The hybrid circuit protection device includes an input configured to couple to a source; an output configured to couple to a load; a loop configured to couple the source to the load; a main switch configured to selectively couple the input to the output; a switching network coupled in parallel with the main switch; and a controller. The controller is configured to determine, in response to a fault current, that the main switch has been disconnected, wherein the fault current has an initial value; and to activate the switching network to current limit the fault current during a fault to a value less than the initial value.

[0007] On the other hand, a method is provided that can be operated by a hybrid circuit protection device to current limit a fault current between a source coupled to an input of the hybrid circuit protection device and a load coupled to an output of the hybrid circuit protection device during a fault. The method includes: determining whether an initial value of a fault current through a main switch is greater than a threshold, wherein the main switch selectively couples the input and output; and in response to determining that the initial value of the fault current is greater than the threshold, disconnecting the main switch; and activating a switching network coupled in parallel with the main switch to current limit the fault current to less than the initial value during a fault.

[0008] On the other hand, a hybrid circuit protection device is provided for current limiting a fault current between a source and a load during a fault. The hybrid circuit protection device includes a first input terminal and a second input terminal configured to couple to a source; a first output terminal and a second output terminal configured to couple to a load; a main switch configured to selectively couple the first input terminal to the first output terminal; and a switch network. The switch network includes a solid-state switch connected in series with an inductor, which couples the first input terminal to the first output terminal. The switch network also includes means for forming selective conductive paths from a junction between the solid-state switch and the inductor to the second input terminal and the second output terminal. The hybrid circuit protection device also includes a controller configured to determine, in response to a fault current, that the main switch has been disconnected, wherein the fault current has an initial value; and to modify the duty cycle of the solid-state switch during a fault to current limit the fault current to be less than the initial value. Attached Figure Description

[0009] These and other features, aspects, and advantages of this disclosure will become better understood when the following detailed description is read with reference to the accompanying drawings, in which the same characters denote the same parts, wherein

[0010] Figure 1 A hybrid circuit protection device in an example embodiment is described.

[0011] Figure 2 Another hybrid circuit protection device is depicted in the example embodiment.

[0012] Figure 3 A hybrid power distribution system in an example embodiment is depicted.

[0013] Figure 4A , Figure 4B and Figure 4C Depicting the period of failure Figure 3 The simulated current and voltage waveforms in the power distribution system.

[0014] Figure 5 Another hybrid power distribution system is depicted in the example embodiment.

[0015] Figure 6A and Figure 6B Depicting the period of failure Figure 5 The simulated current waveform in the power distribution system.

[0016] Figure 7 Another hybrid power distribution system is depicted in the example embodiment.

[0017] Figure 8 Depicting the period of failure Figure 7 The simulated voltage waveform in the power distribution system.

[0018] Figure 9 Another hybrid power distribution system is depicted in the example embodiment.

[0019] Figure 10 This is a flowchart of an exemplary embodiment of a method for current limiting the fault current between a source and a load during a fault.

[0020] Unless otherwise indicated, the accompanying drawings provided herein are intended to illustrate features of embodiments of this disclosure. These features are believed to be applicable to a wide variety of systems, including one or more embodiments of this disclosure. Therefore, the drawings are not intended to include all conventional features known to those skilled in the art for practicing the embodiments disclosed herein. Detailed Implementation

[0021] In the following specification and claims, reference is made to several terms, which shall be defined as having the following meanings.

[0022] Unless the context clearly indicates otherwise, the singular forms “a,” “one,” and “the” include plural references.

[0023] "Optional" or "optionally" means that the event or situation described below may or may not occur, and the description includes both the scenario in which the event occurs and the scenario in which the event does not occur.

[0024] The approximate language used throughout the specification and claims may be used to modify any permissible variation without altering the essential function associated therewith. Therefore, values ​​modified by one or more terms (such as “about,” “approximately,” and “substantially”) are not limited to the specified precise values. In at least some cases, approximate language may correspond to the precision of the instrument used to measure the value. Scope limitations may be combined and / or interchanged throughout this document and throughout the specification and claims, and unless the context or language otherwise indicates, such scopes are identified and include all subscopes contained therein.

[0025] As used herein, the terms “processor” and “computer”, and related terms (e.g., “processing device,” “computing device,” and “controller”), are not limited to those integrated circuits referred to as computers in this art, but broadly refer to microcontrollers, microcomputers, analog computers, programmable logic controllers (PLCs), application-specific integrated circuits (ASICs), and other programmable circuits, and these terms are used interchangeably herein. In the embodiments described herein, “memory” may include, but is not limited to, computer-readable media such as random access memory (RAM) and computer-readable non-volatile media such as flash memory. Alternatively, floppy disks, compact disc-read-only memory (CD-ROM), magneto-optical disks (MODs), and / or digital versatile disks (DVDs) may also be used. Furthermore, in the embodiments described herein, additional input channels may be, but are not limited to, computer peripherals associated with an operator interface such as a touchscreen, mouse, and keyboard. Alternatively, other computer peripherals may be used, including, for example, but not limited to, scanners. Further, in example embodiments, additional output channels may include, but are not limited to, operator interface monitors or head-up displays. Some embodiments involve the use of one or more electronic or computing devices. These devices typically include processors, processing devices, or controllers, such as general-purpose central processing units (CPUs), graphics processing units (GPUs), microcontrollers, reduced instruction set computer (RISC) processors, ASICs, programmable logic controllers (PLCs), field-programmable gate arrays (FPGAs), digital signal processing (DSP) devices, and / or any other circuitry or processing devices capable of performing the functions described herein. The methods described herein may be encoded as executable instructions contained in computer-readable media, including but not limited to storage devices and / or memory devices. When executed by a processing device, such instructions cause the processing device to perform at least a portion of the methods described herein. The examples above are not intended to limit the definition and / or meaning of the terms processor and processing device in any way.

[0026] Renewable energy sources and energy storage are becoming increasingly prevalent in power distribution systems. Since renewable energy sources and energy storage are typically direct current (DC), integrating them into DC power distribution is more efficient, reliable, and cheaper than integrating them into alternating current (AC) power distribution. Therefore, traditional pure AC power distribution systems may evolve into hybrid AC and DC power distribution systems. In traditional AC power distribution protection schemes, reclosers or circuit breakers are installed at the substation or fuse locations, and fuses are installed at the branch lines of each fuse. Fuse reclosers or circuit breakers react to temporary faults by disconnecting and protecting downstream fuses. Fuse reclosers or circuit breakers cannot reclose in the event of a permanent fault, and the downstream fuse near the fault melts. Therefore, customers at the branch line may experience temporary power loss due to the disconnection of the fuse recloser or circuit breaker. This fuse-saving protection design is low-loss, low-cost, and suitable for the high incidence of temporary faults in traditional AC power distribution feeders.

[0027] With the integration of renewable energy sources and energy storage into power distribution systems, a portion of the distribution system can be converted into a DC distribution system for easy and efficient integration. Interface converters can be used to integrate the AC and DC portions of the power distribution system. Protection schemes for DC distribution systems can consider low losses, low cost, and high transient fault rates. AC fault currents and DC fault currents have different characteristics, including different time constants. In hybrid AC and DC distribution, protection coordination between AC and DC protection can also be designed considering the different fault current time constants and protection devices in the AC and DC subsystems.

[0028] The embodiments described herein disclose a hybrid circuit protection device that satisfies the protection speed and coordination constraints between AC and DC power distribution systems. Furthermore, since conventional power distribution protection lacks selectivity in the event of temporary branch line faults, the hybrid circuit protection device disclosed herein provides selectivity. This reduces power distribution downtime and improves system reliability.

[0029] More specifically, the pending application discloses a hybrid circuit protection device that includes fault current limiting capability. During normal operation, current flows through the main circuit breaker or main switch (e.g., a mechanical circuit breaker or a low-loss solid-state circuit breaker), and the protected system operates with high efficiency. During a fault, a switching network connected in parallel with the main circuit breaker is operated to current limit the fault current to the downstream load. The fault current is current-limited, thereby preventing damage to the protected equipment and facilities due to high fault current. Simultaneously, at least one reduced rated power is supplied to the downstream load. The fuse-saving principle of conventional low-cost distribution protection still applies, and system reliability is improved because the load can still operate at reduced power or full rated power during fault current limiting operation.

[0030] Figure 1 A hybrid circuit protection device 100 is depicted in an example embodiment. In this embodiment, the protection device 100 couples one or more DC loads 102 to a DC source 104 and provides protection and fault current limiting capabilities between the DC source 104 and the DC loads 102. In this embodiment, the protection device 100 includes a controller 106 for controlling the operation of the protection device 100, a main switch 108 (also referred to as a main circuit breaker), an auxiliary switch 110, a diode 112, an inductor 114, and one or more sensors 116. The protection device 100 also includes input terminals 118, 119 coupled to the DC source 104 and output terminals 120, 121 coupled to the DC loads 102. Although in other embodiments, the input terminals 119 and the output terminals 121 may be electrically isolated from each other, the input terminals 119 and the output terminals 121 are depicted as sharing a common circuit path. In this embodiment, the auxiliary switch 110, the diode 112, and the inductor 114 form a switch network 132 coupled in parallel with the main switch 108.

[0031] During normal operation, the main switch 108 is closed, providing a low-loss current path between the DC source 104 and the DC load 102. The auxiliary switch 110 is open during normal operation, causing the switch network 132 to be deactivated. If a fault is detected (e.g., if sensor 116 detects a fault current between the DC source 104 and the DC load 102 greater than a threshold), the main switch 108 is disconnected (e.g., via controller 106 or independently of the main switch 108 itself). In some embodiments, the main switch 108 is a mechanical circuit breaker, and an optional solid-state circuit breaker 122 is connected in series with the main switch 108 to reduce the off-time typically associated with the mechanical version of the main switch 108. The controller 106 then activates the switch network 132 by operating the auxiliary switch 110 on and off during switching periods to current limit the fault current from the DC source 104 to the DC load 102 to a value equal to or less than the initial value of the fault current. For example, if the trip current of main switch 108 is 150 amps and the initial fault current is 550 amps, then main switch 108 trips. Switching network 132 operates to current limit the fault current to a value less than 550 amps, for example, 250 amps, which allows DC load 102 to continue being powered by DC source 104. Depending on the power requirements of DC load 102, DC load 102 can continue to operate normally during the fault. For example, DC load 102 may include a DC / DC converter or a DC / AC converter that can continue to operate normally even if the input voltage at the DC / DC converter or DC / AC converter is reduced during the fault.

[0032] When auxiliary switch 110 is turned on during a switching period set by controller 106, DC source 104 is electrically coupled to DC load 102 in series via auxiliary switch 110 and inductor 114. When auxiliary switch 110 is turned off during the switching period, current to DC load 102 is conducted by diode 112 and inductor 114. Typically, auxiliary switch 110, diode 112, and inductor 114 form a buck regulator operated by controller 106 to current limit the fault current supplied to DC load 102. In some embodiments, controller 106 uses a pulse width modulation (PWM) control scheme to current limit the fault current supplied to DC load 102. In some embodiments, protection device 100 includes a mechanical cut-off device 124 for electrically isolating protection device 100 during maintenance. Typically, protection device 100 provides a continuous current limit from DC source 104 to DC load 102 during fault conditions, thereby enabling limiting functionality at DC load 102 even in the presence of a fault. For example, based on the limited fault current supplied by the protection device 100 and the power used by the DC load 102, the DC load 102 can continue to operate normally when the fault is identified and cleared or isolated, thereby minimizing the damage to the DC load 102 during the fault. In some embodiments, the protection device 100 includes a network interface 126 that provides networking capability to the protection device 100. In some embodiments, the controller 106 uses the network interface 126 to coordinate the activities between different protection devices 100 in the power distribution system. In various embodiments, the network interface 126 may include a wired interface or a wireless interface.

[0033] exist Figure 1For the purposes of discussion, the protection device 100 has been simplified, and in other embodiments, the protection device 100 includes different configurations. In this regard, the controller 106 includes any system, component, or device that performs the functions described herein for the controller 106. In some embodiments, the controller includes a processor 128 coupled to memory 130. In some embodiments, the processor 128 executes instructions stored in memory 130 to perform the functions described herein for the controller 106. The main switch 108 includes any system, component, or device that operates in response to a fault detected by the protection device 100 to disconnect input terminal 118 from output terminal 120. In some embodiments, the main switch 108 operates independently of the controller 106 to disconnect input terminal 118 from output terminal 120 (e.g., using information directly from sensor 116). In other embodiments, the main switch 108 operates at the instruction of the controller 106 in response to a fault detected by the controller 106 (e.g., using sensor 116). In some embodiments, the main switch 108 is a mechanical switch that provides a low-loss forward conduction path between the input terminal 118 and the output terminal 120. In other embodiments, the main switch 108 is a low-loss solid-state switch. In embodiments where the main switch 108 is a low-loss solid-state switch, the main switch 108 includes one or more insulated-gate bipolar transistors (IGBTs), reverse-blocking integrated gate-commutated thyristors (RB-IGCTs), silicon carbide metal-oxide-semiconductor field-effect transistors (SiC MOSFETs), gallium nitride (GAN) FETs, etc.

[0034] Auxiliary switch 110 includes any system, component, or device that can be switched by controller 106 to provide a limited current to DC load 102 during a fault. In various embodiments, auxiliary switch 110 includes one or more IGBTs, RB-IGCTs, SiC MOSFETs, GAN FETs, etc. Diode 112 includes any system, component, or device that operates to selectively conduct current when auxiliary switch 110 is off during switching periods. In some embodiments, diode 112 includes an active switching element. For example, in some embodiments, diode 112 may be replaced by a solid-state switch controlled by controller 106 to selectively conduct current during the off interval of the switching period when protection device 100 operates in buck mode to provide a limited fault current to DC load 102.

[0035] Inductor 114 includes any system, component, or device that provides inductance for storing energy in protection device 100 during the on-time interval of the switching period. Sensor 116 measures the current and / or voltage at protection device 100. Sensor 116 is coupled to... Figure 1While the input terminals 118 and 120 are present in the protection device 100, in other embodiments, the sensor 116 may additionally or alternatively be coupled to different sensing points in the protection device 100. In this regard, the sensor 116 includes any system, component, or device that measures information indicating a fault (such as the current flowing through the protection device 100 between the DC source 104 and the DC load 102, the voltage at input terminals 118 and / or 119, the voltage at output terminals 120 and / or 121, harmonic noise measured at input terminals 118, 119, and / or output terminals 120, 121, etc.) or representing a fault.

[0036] In embodiments where the solid-state circuit breaker 122 is used in combination with the mechanical version of the main switch 108, the solid-state circuit breaker 122 includes any system, component, or device that operates to selectively disconnect the circuit path between the input terminal 118 and the output terminal 120. The solid-state circuit breaker 122 may include any type of solid-state device previously described for the main switch 108 and the auxiliary switch 110.

[0037] As discussed above, in some embodiments, the protection device 100 includes a mechanical cut-off device 124 for electrically isolating the protection device 100. In this respect, the mechanical cut-off device 124 includes any system, component, or device that selectively provides electrical isolation to the protection device 100. In some embodiments, the mechanical cut-off device 124 may be manually operated by a service technician during maintenance, or in other embodiments controlled by a controller 106.

[0038] Figure 2 Another hybrid circuit protection device 200 is depicted in another example embodiment. In this embodiment, the protection device 200 couples one or more loads 202 to a source 204. In this embodiment, the source 204 may be a DC source or an AC source, and the load 202 may be a DC load or an AC load. In this embodiment, diode 112 (see...) Figure 1 The auxiliary switch 206 is used instead, which includes any type of solid-state switch previously described. The auxiliary switches 110, 206 and the inductor 114 together form a switch network 208 for protecting the device 200.

[0039] In this embodiment, controller 106 operates switch network 208 to provide bidirectional limited fault current to source 204 or load 202. For example, during a fault at load 202, main switch 108 is disconnected, and controller 106 operates auxiliary switches 110, 206 to current limit the fault current supplied to load 202, similar to previous methods for... Figure 1The protection device 100 operates as described. During a fault at source 204, main switch 108 is disconnected, and controller 106 operates auxiliary switches 110, 206 to current limit the fault current supplied to source 204. For example, if load 202 includes an AC / DC converter with high input capacitance, and a fault occurs at source (in this example, an AC source) 204, protection device 200 operates to current limit the AC fault current supplied back to source 204 by the input capacitance of the AC / DC converter. In another example, if load 202 includes a DC / AC converter with high input capacitance, and a fault occurs at source 204 (in this example, a DC source), protection device 200 operates to current limit the DC fault current supplied back to source 204 by the input capacitance of the AC / DC converter.

[0040] In either case, the limited fault current supplied to load 202 or source 204 includes both DC and AC current. Providing bidirectional current-limited fault current in a hybrid power distribution system advantageously allows protection device 200 to be used for both AC and DC protection, thereby reducing the number of different types of protection devices in a hybrid power distribution system.

[0041] Figure 3 A hybrid power distribution system 300 in an example embodiment is depicted, while Figure 4A , Figure 4B and Figure 4C The analog current and voltage waveforms in the power distribution system 300 during a fault are depicted. In this embodiment, the power distribution system 300 includes an AC source 302 that supplies power to an AC / DC converter 304. The AC / DC converter 304 is coupled to a DC bus 306 via protection devices 100, 200. A first load 308 is coupled to the DC bus 306 via a first fuse 310, and a second load 312 is coupled to the DC bus 306 via a second fuse 314. In the event of a fault 316 occurring at the first load 308, a fault current 402 (see [reference]) flows through the main switch 108. Figure 4A It initially rises to a high current level (e.g., 500A in this simulation, see...). Figure 4A Initially, the voltage 406 on DC bus 306 drops due to the high initial value of fault current 402 (see...). Figure 4B And the diode currents 408, 410, and 412 in the AC / DC converter 304 rise to a high level (see...). Figure 4C Protection devices 100 and 200 disconnect main switch 108 and operate to supply a current-limited fault current 404 to DC bus 306 (see...). Figure 4AThe current-limited fault current 404 stabilizes the voltage 406 on the DC bus 306 and reduces the diode currents 408, 410, and 412 in the AC / DC converter 304. The voltage 406 on the DC bus 306 in the simulation is less than its initial value of 40,000 volts, but in this example it is sufficient to ensure that the second load 312 operates at reduced ratings during fault 316. In this example, the main switch 108 is a mechanical device that does not perform a reclosing operation to attempt to clear fault 316.

[0042] Figure 5 Another hybrid power distribution system 500 in the example embodiment is depicted. Figure 6A and Figure 6B A simulated current waveform in the power distribution system 500 during a fault is depicted. In this embodiment, the power distribution system 500 includes a DC source 502 coupled to a DC bus 504 via protection devices 100, 200. A first load 506 is coupled to the DC bus 504 via a first fuse 508, and a second load 510 is coupled to the DC bus 504 via a second fuse 512. In the event of a fault 514 occurring in the first load 506, the current 602 through the main switch 108 initially rises to a high level (e.g., 150A in this simulation, see [reference]). Figure 6A In this simulation, the main switch 108 is a solid-state device, and the main switch 108 is repeatedly opened and closed (e.g., under the guidance of the controller 106 or automatically opened and closed by the main switch 108 itself) in order to attempt to clear fault 514. Figure 6B Fault 514 is described (see Figure 6B During this period, a first current 604 at the first load 506 and a second current 606 at the second load 510 are observed. After the main switch 108 is reclosed twice, the protection devices 100 and 200 disconnect the main switch 108 and operate to supply a current-limited fault current 608 to the DC bus 504 (e.g., at a switching frequency of 1 kHz, see...). Figure 6A ).

[0043] Figure 7 Another hybrid power distribution system 700 in the example embodiment is depicted, while Figure 8A simulated voltage waveform in the power distribution system 700 during a fault is depicted. In this embodiment, the power distribution system 700 includes a DC source 702 coupled to a DC bus 704 via protection devices 100 and 200. A first load 706 is coupled to the DC bus 704 via a first fuse 708, and a second load 710 is coupled to the DC bus 704 via a second fuse 712. A DC / DC converter 714 is coupled to the DC bus 704 and supplies power to a third load 716. Due to a fault 718 occurring at the first load 706, the output voltage 802 of the DC / DC converter 714 initially drops at T0 when the main switch 108 is opened and the protection devices 100 and 200 provide a limited fault current to the DC bus 704. During fault 718, the output voltage 802 of the DC / DC converter 714 recovers and continues to supply power to the third load 716.

[0044] Figure 9 Another hybrid power distribution system 900 is depicted in an example embodiment. In this embodiment, AC source 902 is electrically coupled to AC bus 904 via protection device 200, AC load 906 is electrically coupled to AC bus 904 via fuse 908, and AC / DC converter 910 has an input coupled to AC bus 904. AC / DC converter 910 is electrically coupled to DC bus 912 via protection devices 100, 200. DC source 914 is also coupled to DC bus 912 via protection devices 100, 200. DC load 916 is electrically coupled to DC bus 912 via fuse 908. In power distribution system 900, protection devices 100, 200 are placed at the fuse and sources 902, 914 to limit the contribution of fault current from sources 902, 914. During fault current limiting operation, downstream healthy loads can be maintained at or below rated voltage by improving the voltage input. At any point of fault in the power distribution system 900, protection devices 100 and 200 respond to the fault and begin current limiting of the fault current. By modulating or limiting the fault current during a fault, high fault currents do not flow through upstream and downstream fault paths, thus preventing damage to equipment and facilities. Simultaneously, for the remaining healthy loads in the power distribution system 900, operation can be maintained at reduced or even fully rated conditions.

[0045] Figure 10 This is a flowchart of a method 1000 for current limiting a fault current between a source and a load, as illustrated in an example embodiment. Method 1000 is discussed in relation to protection devices 100 and 200, although method 1000 may be performed by other devices not shown. Not all steps of method 1000 are included, and method 1000 may include other steps not shown. Furthermore, the steps of method 1000 may be performed in a different order.

[0046] refer to Figure 1 and Figure 2 During normal operation of protection devices 100 and 200, main switch 108 is closed, and switch networks 132 and 208 are deactivated. If a fault occurs, the initial value of the fault current rises to a high level, exceeding a threshold or trip current value (see step 1002), and then main switch 108 is opened (see step 1004). Controller 106 operates switch networks 132 and 208 to current-limit the fault current to below its initial value (see step 1006). For example, the fault current rises to approximately 1100 amps, exceeding the 250-amp trip value of main switch 108, causing main switch 108 to open. Controller 106 operates switch networks 132 and 208 to current-limit the initial 1100-amp fault current to a value equal to or less than 1100 amps. For example, controller 106 operates switch networks 132 and 208 (e.g., by modifying auxiliary switch 110 (see step 1004)). Figure 1 (and / or the duty cycle of auxiliary switch 206) to current limit the fault current to make it equal to 550 amps.

[0047] If the fault is cleared (e.g., by isolating the fault, see step 1008), the main switch 108 is closed (see step 1010) and the controller 106 disables switch networks 132, 208 (see step 1012). The main switch 108 provides a low-loss current path between the source and the load, protecting devices 100, 200 and returning them to normal operation.

[0048] Example technical effects of the apparatus and methods described herein include one or more of the following: (a) improving the performance of mechanical circuit breakers or low-loss solid-state switches during normal operation; (b) current limiting of fault current during a fault; and (c) continuing to supply downstream loads during a fault to minimize disruption to downstream loads during a fault.

[0049] While specific features of various embodiments of this disclosure may be shown in some drawings but not in others, this is merely for convenience. Any feature of the drawings may be referenced and / or claimed in conjunction with any feature of any other drawing, based on the principles of this disclosure.

[0050] This written description uses examples to disclose embodiments, including best practices, and also enables any person skilled in the art to practice the embodiments, including making and using any device or system and performing any incorporated methods. The patentable scope of this disclosure is defined by the claims, but may include other examples that would occur to a person skilled in the art. Such other embodiments are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements that do not substantially differ from the literal language of the claims.

Claims

1. A hybrid circuit protection device for current limiting fault current between a source and a load during a fault, the hybrid circuit protection device comprising: The input is configured to be coupled to the source; The output is configured to be coupled to the load; A loop is configured to couple the source to the load; The main switch is configured to selectively couple the input to the output; A switching network includes a solid-state switch connected in series with an inductor, wherein the solid-state switch connected in series with the inductor is coupled in parallel with the main switch; as well as The controller is configured as follows: In response to the fault current, it is determined that the main switch has been disconnected, wherein the fault current has an initial value; as well as The duty cycle of the solid-state switch is modified to limit the fault current during the fault period so that the fault current is less than the initial value, allowing the load to continue operating.

2. The hybrid circuit protection device according to claim 1, wherein: The solid-state switch has a second terminal and a first terminal coupled to the input. The switching network further includes a diode having an anode coupled to the circuit and a cathode coupled to the second terminal of the solid-state switch. The inductor has a third terminal coupled to the cathode of the diode and a fourth terminal coupled to the output.

3. The hybrid circuit protection device according to claim 2 further includes: At least one mechanical cut-off device provides electrical isolation for the hybrid circuit protection device.

4. The hybrid circuit protection device according to claim 1, wherein: The main switch includes a mechanical circuit breaker. The hybrid circuit protection device also includes a solid-state circuit breaker, which is connected in series with the mechanical circuit breaker between the input and the output. The controller is also configured to disconnect the solid-state circuit breaker in response to the fault current.

5. The hybrid circuit protection device according to claim 1, wherein: The controller is also configured to: It is confirmed that the main switch has been closed; and The solid-state switch is deactivated to disable the current path between the input and the output through the switch network.

6. The hybrid circuit protection device according to claim 1, further comprising: A current sensor is configured to sense the fault current between the input and the output. The controller is further configured to: The fault current is measured using the current sensor; Determine whether the initial value of the fault current is greater than a threshold; and The main switch is turned off in response to determining that the initial value is greater than the threshold.

7. The hybrid circuit protection device according to claim 1, wherein: The solid-state switch includes a first auxiliary switch having a second terminal and a first terminal coupled to the input. The switch network further includes a second auxiliary switch having a third terminal coupled to the circuit and a fourth terminal coupled to the second terminal of the first auxiliary switch. The inductor has a fifth terminal coupled to the second terminal of the first auxiliary switch and the fourth terminal of the second auxiliary switch, and the inductor has a sixth terminal coupled to the output. The controller is also configured to modify the duty cycle of the second auxiliary switch during the fault to current limit the fault current.

8. A method operable by a hybrid circuit protection device for limiting a fault current between a source coupled to an input of the hybrid circuit protection device and a load coupled to an output of the hybrid circuit protection device during a fault, the method comprising: Determine whether the initial value of the fault current through the main switch is greater than a threshold, wherein the main switch selectively couples the input to the output; as well as In response to determining that the initial value of the fault current is greater than the threshold: Disconnect the main switch; as well as The duty cycle of a solid-state switch connected in series with an inductor is modified to current limit the fault current during the fault period so that the fault current is less than the initial value, allowing the load to continue operating, wherein the solid-state switch connected in series with the inductor is coupled in parallel with the main switch.

9. The method of claim 8, further comprising: Determine whether the fault has been cleared; as well as In response to determining that the fault has been cleared: Close the main switch; as well as Deactivate the solid-state switch to disable the current path between the input and the output.

10. The method according to claim 8, wherein: The loop couples the source to the load. The solid-state switch has a second terminal and a first terminal coupled to the input. The hybrid circuit protection device further includes a diode having an anode coupled to the circuit and a cathode coupled to the second terminal of the solid-state switch. The inductor has a third terminal coupled to the cathode of the diode and a fourth terminal coupled to the output.

11. The method according to claim 8, wherein: The main switch includes a mechanical circuit breaker. The hybrid circuit protection device also includes a solid-state circuit breaker, which is connected in series with the mechanical circuit breaker between the input and the output. The method also includes disconnecting the solid-state circuit breaker in response to a fault current.

12. The method according to claim 8, wherein: The hybrid circuit protection device further includes a current sensor configured to sense a fault current between the input and the output; The method further includes: The fault current is measured using the current sensor; Determine whether the initial value of the fault current is greater than a threshold; and The main switch is turned off in response to determining that the initial value is greater than the threshold.

13. The method according to claim 8, wherein: The loop couples the source to the load. The solid-state switch includes a first auxiliary switch having a second terminal and a first terminal coupled to the input. The hybrid circuit protection device further includes a second auxiliary switch, the second auxiliary switch having a third terminal coupled to the circuit and a fourth terminal coupled to the second terminal of the first auxiliary switch, and The inductor has a fifth terminal coupled to the second terminal of the first auxiliary switch and the fourth terminal of the second auxiliary switch, and the inductor has a sixth terminal coupled to the output. The method further includes modifying the duty cycle of the first auxiliary switch and the second auxiliary switch during the fault to current limit the fault current.

14. The method of claim 8, further comprising: It is confirmed that the main switch is closed; as well as Deactivate the solid-state switch to disable the current path between the input and the output.

15. A hybrid circuit protection device for current limiting a fault current between a source and a load during a fault, the hybrid circuit protection device comprising: The first input terminal and the second input terminal are configured to be coupled to the source; The first output terminal and the second output terminal are configured to be coupled to the load; The main switch is configured to selectively couple the first input terminal to the first output terminal; Switching networks, including: A solid-state switch connected in series with the inductor, the solid-state switch connecting the first input terminal to the first output terminal; and A device for forming a selective conduction path, the selective conduction path being from the junction between the solid-state switch and the inductor to the second input terminal and the second output terminal; and The controller is configured as follows: In response to the fault current, it is determined that the main switch has been disconnected, wherein the fault current has an initial value; and The duty cycle of the solid-state switch is modified to limit the fault current during the fault period so that the fault current is less than the initial value, allowing the load to continue operating.

16. The hybrid circuit protection device according to claim 15, wherein: The device includes a diode having an anode coupled to the second input terminal and the second output terminal, and a cathode coupled to the junction between the solid-state switch and the inductor.

17. The hybrid circuit protection device according to claim 15, wherein: The solid-state switch includes a first solid-state switch. The device includes a second solid-state switch, and The controller is also configured to modify the duty cycle of the second solid-state switch to current limit the fault current during the fault so that the fault current is less than the initial value.

18. The hybrid circuit protection device according to claim 15, further comprising: At least one mechanical cut-off device provides electrical isolation for the hybrid circuit protection device.

19. The hybrid circuit protection device according to claim 15, wherein: The main switch includes a mechanical circuit breaker. The hybrid circuit protection device also includes a solid-state circuit breaker, which is connected in series with the mechanical circuit breaker between the first input terminal and the first output terminal. The controller is also configured to disconnect the solid-state circuit breaker in response to the fault current.

20. The hybrid circuit protection device according to claim 15, wherein: The controller is also configured to: It is confirmed that the main switch is closed; as well as Modify the duty cycle of the solid-state switch to disable the current path through the switch network between the first input terminal and the first output terminal.

21. The hybrid circuit protection device according to claim 15, further comprising: A current sensor is configured to sense the fault current between the first input terminal and the first output terminal. The controller is further configured to: The fault current is measured using the current sensor; Determine whether the initial value of the fault current is greater than a threshold; and The main switch is turned off in response to determining that the initial value is greater than the threshold.

22. The hybrid circuit protection device according to claim 21, wherein: The controller is also configured to: The main switch is operated to perform a series of reclosing operations in an attempt to clear the fault; as well as In response to determining that the main switch has performed the last reclosing operation in the series of reclosing operations and that the main switch remains open, the duty cycle of the solid-state switch is modified to limit the fault current.

23. The hybrid circuit protection device according to claim 15, wherein: The main switch is configured to perform a series of reclosing operations to attempt to clear the fault, and The controller is configured to modify the duty cycle of the solid-state switch to limit the fault current in response to determining that the main switch has performed the last reclosing operation in the series of reclosing operations and that the main switch remains open.

24. The hybrid circuit protection device according to claim 15, wherein: The main switch includes one or more insulated gate bipolar transistors, one or more reverse blocking integrated gate commutated thyristors, one or more silicon carbide metal oxide semiconductor field-effect transistors, and / or one or more gallium nitride field-effect transistors.

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