Hybrid circuit breaker
Patent Information
- Application Number
- JP2022203865
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2021-12-21
- Filing Date
- 2022-12-21
- Publication Date
- 2025-12-26
AI Technical Summary
Conventional circuit breakers in DC power distribution systems face challenges in selectively isolating faulted branches without disrupting non-faulted loads, leading to undesirable de-energization and inefficiencies.
A hybrid circuit protection device with a main switch and a parallel switching network, controlled by a controller, that limits fault current to prevent damage and maintains load operation by reducing fault current to a manageable level.
The hybrid device effectively limits fault currents, preventing equipment damage while maintaining load functionality, enhancing system reliability and reducing downtime.
Smart Images
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Abstract
Description
Technical Field
[0001] [Statement Regarding Federally Sponsored Research and Development]
[0001] This invention was made with government support under Contract No. DE-AC02-06CH11357 awarded by the Department of Energy. The government has certain rights in this invention.
[0002]
[0002] The field of this disclosure relates to circuit breakers, and more particularly, to hybrid circuit breakers that include fault current limiters.
Background Art
[0003]
[0003] A circuit breaker is a device installed within a circuit path to protect downstream loads on a branch circuit during a fault. During a fault condition in the downstream load, the circuit breaker is designed to trip open and de-energize the branch powered by the circuit breaker. However, de-energizing the branch can also de-energize other loads on the branch, which is undesirable, particularly in direct current (DC) distribution systems.
[0004]
[0004] Therefore, it is desirable to improve the operation and performance of circuit breakers, and more specifically, the operation and performance of circuit breakers used in DC distribution systems.
Summary of the Invention
[0005]
[0005] In one embodiment, 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 return configured to couple the source to a 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 control device. The control device is configured to determine in response to a fault current that the main switch is open, where the fault current has an initial value, and to activate the switching network to current-limit the fault current during a fault so that it is less than the initial value.
[0006]
[0006] In another embodiment, a hybrid circuit protector-operable method is provided for current-limiting a fault current between a source coupled to the input of the hybrid circuit protector and a load coupled to the output of the hybrid circuit protector during a fault. The method includes determining whether an initial value of the fault current through a main switch is greater than a threshold, where the main switch selectively couples its input to an output and opens the main switch in response to determining that the initial value of the fault current is greater than a threshold, and activating a switching network coupled in parallel with the main switch to current-limit the fault current to less than an initial value during a fault.
[0007]
[0007] In another embodiment, 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 with the first output terminal, and a switching network. The switching network includes a solid switch in series with an inductor, the solid switch in series with the inductor coupling the first input terminal with the first output terminal. The switching network further includes a device that forms a selective conduction path from the junction between the solid switch and the inductor to the second input terminal and the second output terminal. The hybrid circuit protection device further includes a control device configured to determine that the main switch is open in response to a fault current, where the fault current has an initial value, and to modify the duty cycle of the solid switch to current-limit the fault current to be less than the initial value during a fault.
[0008]
[0008] These and other features, aspects and advantages of the present disclosure will be better understood by reading the following embodiments for carrying out the invention with reference to the attached drawings, in which similar reference numerals throughout the drawings represent similar parts. [Brief explanation of the drawing]
[0009] [Figure 1] Figure 1 illustrates a hybrid circuit protection device in an example embodiment. [Figure 2] Figure 2 illustrates another hybrid circuit protection device in an exemplary embodiment. [Figure 3] Figure 3 illustrates a hybrid power distribution system in an example embodiment. [Figure 4A] Figure 4A illustrates the simulated current waveform in the power distribution system shown in Figure 3 during a malfunction. [Figure 4B] Figure 4B illustrates the simulated voltage waveforms in the power distribution system shown in Figure 3 during a malfunction. [Figure 4C] Figure 4C illustrates the simulated current waveform in the power distribution system shown in Figure 3 during a malfunction. [Figure 5] Figure 5 illustrates another hybrid power distribution system in an exemplary embodiment. [Figure 6A] Figure 6A illustrates the simulated current waveform in the power distribution system shown in Figure 5 during a malfunction. [Figure 6B] Figure 6B illustrates the simulated current waveform in the power distribution system shown in Figure 5 during a malfunction. [Figure 7] Figure 7 illustrates another hybrid power distribution system in an exemplary embodiment. [Figure 8] Figure 8 illustrates the simulated voltage waveforms in the power distribution system shown in Figure 7 during a malfunction. [Figure 9] Figure 9 illustrates another hybrid power distribution system in an exemplary embodiment. [Figure 10] Figure 10 is a flowchart of a method for current-limiting a fault current between a source and a load during a fault, in an exemplary embodiment. [Modes for carrying out the invention]
[0010]
[0019] Unless otherwise indicated, the drawings provided herein are intended to illustrate features of embodiments of the disclosure. These features are considered applicable to a wide variety of systems comprising one or more embodiments of the disclosure. Accordingly, the drawings are not intended to include all prior art features known to those skilled in the art that are necessary for carrying out the embodiments disclosed herein.
[0011]
[0020] In the following specification and claims, several terms are referenced and defined as having the following meanings:
[0012]
[0021] The singular forms "a," "an," and "the" include multiple references unless otherwise specified by the context.
[0013]
[0022] "Optional" or "optional" means that the event or situation described below may or may not occur, and that the description includes both cases in which the event occurs and cases in which it does not occur.
[0014]
[0023] Where used herein, throughout this specification and the claims, approximate language may be applied to modify any quantitative expression that may vary within an acceptable range without altering its fundamental function. Thus, values modified by one or more terms such as “about,” “approximately,” and “substantially” should not be limited to the exact value specified. In at least some cases, approximate language may correspond to the precision of an instrument for measuring a value. Herein, and throughout this specification and the claims, scope limitations may be combined and / or substituted, such scopes include all partial scopes that are identified and contained therein unless otherwise indicated by context or language.
[0015]
[0024] As used herein, the terms “processor” and “computer,” as well as related terms such as “processing device,” “calculating device,” and “control device,” are not limited to integrated circuits referred to as computers in the art, but broadly include microcontrollers, microcomputers, analog computers, programmable logic control devices (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 multi-purpose disks (DVDs) may also be used. 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, but are not limited to, a scanner. Furthermore, in exemplary embodiments, additional output channels may include, but are not limited to, an operator interface monitor or a head-up display device. Some embodiments involve the use of one or more electronic or computing devices. Such devices typically include processors, processing units, or control devices, such as general-purpose central processing units (CPUs), graphics processing units (GPUs), microcontrollers, reduced instruction set computer (RISC) processors, ASICs, programmable logic control units (PLCs), field-programmable gate arrays (FPGAs), digital signal processing (DSP) devices, and / or any other circuits or processing units capable of performing the functions described herein. The methods described herein may be encoded as executable instructions embodied in a computer-readable medium, including, but not limited to, storage devices and / or memory devices. When such instructions are executed by a processing unit, they cause the processing unit to perform at least a portion of the methods described herein.The above examples are not intended to limit in any way the definition and / or meaning of the terms processor and processing device.
[0016]
[0025] Renewable energy sources and energy storage are becoming increasingly prevalent in the power distribution system. Renewable energy sources and energy storage are typically direct current (DC), so their integration into DC power distribution is more efficient, reliable, and less expensive than AC power distribution. Thus, conventional pure AC power distribution systems can potentially evolve into hybrid AC and DC power distribution systems. In conventional AC power distribution protection schemes, reclosers or circuit breakers are installed at substations or feeders, and fuses are installed at the laterals of each feeder. The feeder recloser or breaker responds to temporary faults by opening the downstream fuses to protect them. The feeder recloser or breaker cannot reclose in the event of a permanent fault, and the fuses downstream near the fault melt. Thus, customers on the lateral can experience temporary power loss due to the opening of the feeder recloser or breaker. This fuse-saving protection design is low-loss, low-cost, and suitable for the high occurrence of temporary faults in conventional AC power distribution feeders.
[0017]
[0026] With the integration of renewable energy sources and energy storage into the power distribution system, a section of the power distribution system can become a DC power distribution system for easy and efficient integration. Interface converters can be utilized to integrate the AC and DC portions of the power distribution system. Protection schemes for DC power distribution systems can consider the low-loss, low-cost, and high occurrence of temporary faults of power distribution protection. AC fault currents and DC fault currents have different characteristics, including different time constants. In hybrid AC and DC power distribution, protection coordination between AC protection and DC protection can also be designed considering the different time constants of fault currents and protection devices in the AC and DC subsystems.
[0018]
[0027] Embodiments described herein disclose a hybrid circuit protection device that satisfies the constraints of protection speed and coordination between an AC distribution system and a DC distribution system. Furthermore, since conventional distribution protection is not selective for transient faults in sidings, the hybrid circuit protection device disclosed herein provides selectivity. In this regard, distribution downtime is reduced and system reliability is improved.
[0019]
[0028] More specifically, the pending application discloses a hybrid circuit protection device that includes fault current limiting capability. Under normal operation, current flows through a main circuit breaker or main switch (e.g., a mechanical circuit breaker or a low-loss solid circuit breaker), and the protected system operates efficiently. In the event of a fault, a switching network in parallel with the main circuit breaker is activated to limit the fault current to downstream loads. The fault current is current-limited, thus preventing damage to protected equipment and devices from high fault currents. At the same time, at least reduced rated power is supplied to the downstream loads. The fuse-saving principle of conventional low-cost distribution protection remains applicable, and the reliability of the system is improved because the loads can still operate at reduced rated power or full rated power during the fault current limiting operation.
[0020]
[0029] Figure 1 illustrates a hybrid circuit protection device 100 in an exemplary 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 capability between the DC source 104 and the DC loads 102. In this embodiment, the protection device 100 includes a control device 106 that controls the operation of the protection device 100, a main switch 108 (also called a main circuit breaker), an auxiliary switch 110, a diode 112, an inductor 114, and one or more sensors 116. The protection device 100 further includes input terminals 118, 119 coupled to the DC source 104 and output terminals 120, 121 coupled to the DC loads 102. The input terminals 119 and output terminals 121 are shown as sharing a common circuit path, but in other embodiments, the input terminals 119 and output terminals 121 may be electrically isolated from each other. In this embodiment, the auxiliary switch 110, the diode 112, and the inductor 114 form a switching network 132 that is coupled in parallel with the main switch 108.
[0021]
[0030] 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, and as a result, the switching network 132 is deactivated. If a fault is detected (for example, if sensor 116 detects a fault current between the DC source 104 and the DC load 102 that is greater than a threshold), the main switch 108 is opened (for example, by the control unit 106 or independently by the main switch 108 itself). In some embodiments, the main switch 108 is a mechanical circuit breaker, and an optional solid circuit breaker 122 is in series with the main switch 108 to reduce the turn-off time normally associated with the mechanical main switch 108. The control unit 106 then activates the switching network 132 by operating the auxiliary switch 110 on and off over the switching period to limit the fault current from the DC source 104 to the DC load 102 to a value less than the initial value of the fault current. For example, if the trip current value of the main switch 108 is 150 amperes and the initial fault current value is 550 amperes, the main switch 108 will trip and open. The switching network 132 operates to limit the fault current to a value less than 550 amperes, for example, 250 amperes, which allows the DC load 102 to continue to be powered by the DC source 104. Depending on the power requirements of the DC load 102, the DC load 102 may continue to operate normally during the fault. For example, the DC load 102 may include a DC / DC converter or a DC / AC converter, which may continue to operate normally even if the input voltage in the DC / DC converter or DC / AC converter drops during the fault.
[0022]
[0031] When the auxiliary switch 110 is on during a switching period set by the control device 106, the DC source 104 is electrically coupled in series to the DC load 102 through the auxiliary switch 110 and the inductor 114. When the auxiliary switch 110 is off during a switching period, current to the DC load 102 is conducted by the diode 112 and the inductor 114. Generally, the auxiliary switch 110, the diode 112, and the inductor 114 form a buck regulator operated by the control device 106 to current-limit the fault current supplied to the DC load 102. In some embodiments, the control device 106 uses a pulse-width modulation (PWM) control scheme to current-limit the fault current supplied to the DC load 102. In some embodiments, the protective device 100 includes mechanical disconnects 124 used to galvanically isolate the protective device 100 during maintenance. Generally, the protection device 100 provides a continuous, limited current flow from the DC source 104 to the DC load 102 during a fault condition, thereby enabling limited functionality in the DC load 102 even when a fault is present. For example, depending on the limited fault current supplied by the protection device 100 and the power utilized by the DC load 102, the DC load 102 may continue to operate normally while the fault is identified, resolved, or isolated, thereby minimizing disruption to the DC load 102 during the fault. In some embodiments, the protection device 100 includes a network interface 126, which provides the protection device 100 with networking capabilities. In some embodiments, the network interface 126 is used by the control unit 106 to coordinate the activity between different protection devices 100 in a power distribution system. In various embodiments, the network interface 126 may include a wired interface or a wireless interface.
[0023]
[0032] In Figure 1, the protective device 100 is simplified for illustrative purposes, and in other embodiments, the protective device 100 includes a different configuration. In this regard, the control unit 106 includes any system, component, or device that performs the functions described herein with respect to the control unit 106. In some embodiments, the control unit includes a processor 128 coupled to a memory 130. In some embodiments, the processor 128 executes instructions stored in the memory 130 to perform the functions described herein with respect to the control unit 106. The main switch 108 includes any system, component, or device that operates to disconnect the input terminal 118 from the output terminal 120 in response to a fault detected by the protective device 100. In some embodiments, the main switch 108 operates independently of the control unit 106 to disconnect the input terminal 118 from the output terminal 120 (for example, by directly utilizing information from the sensor 116). In other embodiments, the main switch 108 operates under the direction of the control device 106 in response to the control device 106 detecting a fault (for example, using the sensor 116). In some embodiments, the main switch 108 is a mechanical switch, which 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 such as an insulated-gate bipolar transistor (IGBT), a reverse-blocking-integrated-gate commutated thyristor (RB-IGCT), a silicon carbide metal oxide semiconductor field-effect transistor (SiC MOSFET), or a gallium nitride (GAN) FET.
[0024]
[0033] The auxiliary switch 110 includes any system, component, or device that can be switched by the control device 106 to provide a limited current to the DC load 102 in the event of a fault. In various embodiments, the auxiliary switch 110 includes one or more IGBTs, RB-IGCTs, SiC MOSFETs, GAN FETs, etc. The diode 112 includes any system, component, or device that operates to selectively conduct current when the auxiliary switch 110 is off during the switching period. In some embodiments, the diode 112 includes an active switching element. For example, in some embodiments, the diode 112 may be replaced by a solid switch, which is controlled by the control device 106 to selectively conduct current during the off interval of the switching period when the protection device 100 operates in buck mode to supply a limited fault current to the DC load 102.
[0025]
[0034] The inductor 114 includes any system, component, or device that provides inductance for storing energy during the ON interval of the switching period for the protection device 100. The sensor 116 measures current and / or voltage in the protection device 100. In Figure 1, the sensor 116 is coupled to input terminal 118 and output terminal 120, but in other embodiments, the sensor 116 may be coupled to different sensing points in the protection device 100, either as an addition or instead. In this regard, the sensor 116 includes any system, component, or device that measures information indicating or representing a fault, such as current passing through the protection device 100 between the DC source 104 and the DC load 102, voltage at input terminal 118 and / or input terminal 119, voltage at output terminal 120 and / or output terminal 121, harmonic noise measured at input terminals 118, 119 and / or output terminals 120, 121, etc.
[0026]
[0035] In embodiments in which the solid circuit breaker 122 is used in combination with a mechanical main switch 108, the solid circuit breaker 122 includes any system, component, or device that operates to selectively open the circuit path between the input terminal 118 and the output terminal 120. The solid circuit breaker 122 may include any type of solid device described above for the main switch 108 and the auxiliary switch 110.
[0027]
[0036] As described above, in some embodiments, the protective device 100 includes a mechanical cut section 124 for galvanically insulating the protective device 100. In this regard, the mechanical cut section 124 includes any system, component, or device that selectively provides galvanic insulation to the protective device 100. In some embodiments, the mechanical cut section 124 may be operated manually by a service technician during maintenance, or in other embodiments, it may be controlled by the control device 106.
[0028]
[0037] Figure 2 illustrates another hybrid circuit protection device 200 in an embodiment that is another example. 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 loads 202 may be DC loads or AC loads. In this embodiment, the diode 112 (see Figure 1) is replaced by an auxiliary switch 206, which includes any of the aforementioned types of solid switches. The auxiliary switches 110, 206 and the inductor 114 collectively form a switching network 208 for the protection device 200.
[0029]
[0038] The control device 106 operates the switching network 208 in this embodiment to provide a bidirectional, limited fault current to either the source 204 or the load 202. For example, during a fault in the load 202, the main switch 108 is opened, and the control device 106 operates the auxiliary switches 110, 206 to limit the fault current supplied to the load 202, similar to the functions previously described for the protection device 100 in Figure 1. During a fault in the source 204, the main switch 108 is opened, and the control device 106 operates the auxiliary switches 110, 206 to limit the fault current supplied to the source 204. For example, if the load 202 includes an AC / DC converter with high input capacitance and a fault occurs in the source 204 (an AC source in this example), the protection device 200 operates to limit the AC fault current supplied to the source 204 by the input capacitance of the AC / DC converter. In another example, if the load 202 includes a DC / AC converter with high input capacitance, and a fault occurs in the source 204 (a DC source in this example), the protection device 200 operates to limit the DC fault current supplied to the source 204 by the input capacitance of the AC / DC converter.
[0030]
[0039] In either case, the limited fault current supplied to the load 202 or source 204 includes both DC and AC currents. Providing bidirectional current-limited fault currents in a hybrid distribution system is advantageous because it allows the protection device 200 to be used for both AC and DC protection, thereby reducing the number of different types of protection devices in the hybrid distribution system.
[0031]
[0040] Figure 3 illustrates a hybrid power distribution system 300 in an exemplary embodiment, and Figures 4A, 4B, and 4C illustrate simulated current and voltage waveforms in the power distribution system 300 during a fault. In this embodiment, the power distribution system 300 includes an AC source 302, which supplies power to an AC / DC converter 304. The AC / DC converter 304 is coupled to a DC bus 306 via protective 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. If a fault 316 is present in the first load 308, the fault current 402 (see Figure 4A) through the main switch 108 initially rises to a high current level (e.g., 500A in this simulation, see Figure 4A). Initially, the voltage 406 on the DC bus 306 temporarily drops due to the high initial value of the fault current 402 (see Figure 4B), and the diode currents 408, 410, and 412 in the AC / DC converter 304 rise to high levels (see Figure 4C). The protection devices 100 and 200 operate to open the main switch 108 and supply the current-limited fault current 404 (see Figure 4A) to the DC bus 306, which stabilizes the voltage 406 on the DC bus 306 and reduces the diode currents 408, 410, and 412 in the AC / DC converter 304. In the simulation, the voltage 406 on the DC bus 306 is less than its initial value of 40,000 volts, but in this example it is sufficient to ensure reduced rated operation of the second load 312 during fault 316. In this example, the main switch 108 is a mechanical device that does not perform a re-closing operation to attempt to resolve fault 316.
[0032]
[0041] Figure 5 illustrates another hybrid power distribution system 500 in an exemplary embodiment, and Figures 6A and 6B illustrate simulated current waveforms in the power distribution system 500 during a fault. In this embodiment, the power distribution system 500 includes a DC source 502, which is coupled to a DC bus 504 via protective 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. If a fault 514 is present 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 Figure 6A). In this simulation, the main switch 108 is a solid device, and the main switch 108 is repeatedly opened and closed (e.g., under the direction of the control device 106, or automatically by the main switch 108 itself) in an attempt to resolve the fault 514. Figure 6B illustrates the first current 604 at the first load 506 and the second current 606 at the second load 510 during fault 514 (see Figure 6B). After the main switch 108 is turned on twice, the protective devices 100, 200 operate to open the main switch 108 and supply the current-limited fault current 608 to the DC bus 504 (see Figure 6A, for example, at a switching frequency of 1 kilohertz).
[0033]
[0042] Figure 7 illustrates another hybrid power distribution system 700 in an exemplary embodiment, and Figure 8 illustrates a simulated voltage waveform in the power distribution system 700 during a fault. In this embodiment, the power distribution system 700 includes a DC source 702, which is coupled to a DC bus 704 via protective devices 100, 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 a third load 716. If a fault 718 is present in the first load 706, the output voltage 802 of the DC / DC converter 714 initially drops temporarily at T0 when the main switch 108 is opened, and the protective devices 100, 200 supply a limited fault current to the DC bus 704. The output voltage 802 of the DC / DC converter 714 recovers and continues to supply power to the third load 716 during the failure 718.
[0034]
[0043] Figure 9 illustrates another hybrid power distribution system 900 in an exemplary embodiment. In this embodiment, an AC source 902 is electrically coupled to an AC bus 904 via a protective device 200, an AC load 906 is electrically coupled to an AC bus 904 via a fuse 908, and an AC / DC converter 910 has an input coupled to an AC bus 904. The AC / DC converter 910 is electrically coupled to a DC bus 912 via protective devices 100, 200. A DC source 914 is also coupled to a DC bus 912 via protective devices 100, 200. A DC load 916 is electrically coupled to a DC bus 912 via a fuse 908. In the power distribution system 900, protective devices 100, 200 are located in the feed lines and sources 902, 914 to limit the contribution of fault current from sources 902, 914. During fault current limiting operation, downstream healthy loads may maintain full rated operation or reduced rated operation with improved voltage input. In any fault in the distribution system 900, the protective devices 100, 200 react to the fault and begin to limit the fault current. By modulating or limiting the fault current during a fault, high fault currents are prevented from flowing through the upstream and downstream fault paths, thus preventing damage to equipment and devices. Simultaneously, reduced rated operation or even full rated operation may be maintained for the remaining healthy loads in the distribution system 900.
[0035]
[0044] Figure 10 is a flowchart of method 1000 for current-limiting a fault current between a source and a load in an exemplary embodiment. Method 1000 is described with respect to protective devices 100, 200, but method 1000 may be carried out by other devices not shown. The steps of method 1000 are not exhaustive, and method 1000 may include other steps not shown. Furthermore, the steps of method 1000 may be carried out in a different order.
[0036]
[0045] Referring to Figures 1 and 2, during the normal operation of the protective devices 100 and 200, the main switch 108 is closed and the switching networks 132 and 208 are deactivated. In the event of a fault, the initial value of the fault current rises to a high level above the threshold or trip current value (see step 1002), after which the main switch 108 opens (see step 1004). The control unit 106 operates the switching networks 132 and 208 to limit the fault current to a value less than its initial value (see step 1006). For example, the fault current rises to approximately 1100 amperes, which is higher than the trip value of 250 amperes for the main switch 108, causing the main switch 108 to open. The control unit 106 operates the switching networks 132 and 208 to limit the initial 1100 ampere fault current to a value less than 1100 amperes. For example, the control device 106 operates the switching networks 132, 208 (for example, by modifying the duty cycle of auxiliary switch 110 (see Figure 1) and / or auxiliary switch 206) to limit the fault current to 550 amperes.
[0037]
[0046] If the fault is resolved (for example, by isolating the fault) (see step 1008), the main switch 108 is closed (see step 1010), and the control unit 106 deactivates the switching networks 132, 208 (see step 1012). The protective devices 100, 200 return to normal operation by providing a low-loss current path between the source and the load through the main switch 108.
[0038]
[0047] Examples of technical effects of the apparatus and methods described herein include one or more of the following: (a) improved performance using mechanical circuit breakers or low-loss solid switches during normal operation; (b) current limiting of fault current during a fault; and (c) continued supply to downstream loads during a fault to minimize interruption to downstream loads during a fault.
[0039]
[0048] Certain features of various embodiments of this disclosure may be shown in some drawings and not in others, for convenience only. In accordance with the principles of this disclosure, any feature in a drawing may be referenced and / or described in a claim in combination with any feature in any other drawing.
[0040]
[0049] This specification discloses embodiments including the best mode and uses examples to enable any person skilled in the art to carry out the embodiments, including making and using any device or system and performing any incorporated method. The patentable scope of this disclosure is defined by the claims and may include other examples that a person skilled in the art can conceive. Such other examples are intended to be within the claims if they have structural elements that are not different from the literal wording of the claims, or if they include equivalent structural elements that are not substantially different from the literal wording of the claims.
Claims
1. 1. 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: an input configured to couple to the source; an output configured to couple to the load; a return line configured to couple the source to the load; a main switch configured to selectively couple the input to the output; a switching network comprising a solid state switch in series with an inductor, wherein the solid state switch in series with the inductor is coupled in parallel with the main switch; a control device, the control device comprising: determining that the main switch is open in response to the fault current, wherein the fault current has an initial value; modifying the duty cycle of the solid state switch to current limit the fault current to be less than the initial value during a fault; A hybrid circuit protection device configured to:
2. the solid-state switch having a first terminal coupled to the input and a second terminal; the switching network further comprising a diode having an anode coupled to the return line and a cathode coupled to the second terminal of the solid-state switch; 2. The hybrid circuit protection device of claim 1, wherein 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 of claim 2 further comprising at least one mechanical disconnect that provides galvanic isolation for the hybrid circuit protection device.
4. The main switch comprises a mechanical circuit breaker; the hybrid circuit protection device further comprising a solid-state circuit breaker between the input and the output in series with the mechanical circuit breaker; The hybrid circuit protection device of claim 1 , wherein the controller is further configured to open the solid-state circuit breaker in response to the fault current.
5. The control device determining that the main switch is closed; deactivating the solid-state switch to disable a current path through the switching network between the input and the output; 10. The hybrid circuit protection device of claim 1, further configured to:
6. a current sensor configured to sense the fault current between the input and the output; The control device measuring the fault current using the current sensor; determining whether the initial value of the fault current is greater than a threshold; opening the main switch in response to determining that the initial value is greater than the threshold value; 10. The hybrid circuit protection device of claim 1, further configured to:
7. the solid-state switch comprises a first auxiliary switch having a first terminal coupled to the input and a second terminal; the switching network further comprises a second auxiliary switch having a third terminal coupled to the return line 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, the inductor having a sixth terminal coupled to the output; 2. The hybrid circuit protection device of claim 1, wherein the controller is further configured to modify a duty cycle of the second auxiliary switch to current limit the fault current during a fault.
8. 1. A method operable by a hybrid circuit protection device for current 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: determining whether an initial value of the fault current through a main switch is greater than a threshold, wherein the main switch selectively couples the input to the output; in response to determining that the initial value of the fault current is greater than the threshold value; opening the main switch; modifying a duty cycle of a solid state switch in series with an inductor to current limit the fault current to be less than the initial value during a fault, wherein the solid state switch in series with the inductor is coupled in parallel with the main switch; A method comprising:
9. determining whether the fault has been cleared; In response to determining that the fault has been cleared, closing the main switch; 9. The method of claim 8, further comprising: deactivating the solid-state switch to disable a current path between the input and the output.
10. 1. 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: a first input terminal and a second input terminal configured to couple to the source; a first output terminal and a second output terminal configured to be coupled to the load; a main switch configured to selectively couple the first input terminal to the first output terminal; A switching network; a control device; The switching network includes: a solid state switch in series with an inductor, wherein the solid state switch in series with the inductor couples the first input terminal to the first output terminal; and a device for forming a selective conduction path from a junction between the solid-state switch and the inductor to the second input terminal and the second output terminal; The control device determining that the main switch is open in response to the fault current, wherein the fault current has an initial value; modifying the duty cycle of the solid state switch to current limit the fault current to be less than the initial value during a fault; A hybrid circuit protection device configured to:
11. 11. The hybrid circuit protection device of claim 10, wherein the hybrid circuit protection device comprises 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.
12. the solid-state switch comprises a first solid-state switch; the hybrid circuit protection device includes a second solid-state switch; 11. The hybrid circuit protection device of claim 10, wherein the controller is further configured to modify the duty cycle of the second solid-state switch to current limit the fault current to less than the initial value during a fault.
13. The hybrid circuit protection device of claim 10 further comprising at least one mechanical disconnect that provides galvanic isolation for the hybrid circuit protection device.
14. The main switch comprises a mechanical circuit breaker; the hybrid circuit protection device further comprising a solid-state circuit breaker in series with the mechanical circuit breaker between the first input terminal and the first output terminal; The hybrid circuit protection device of claim 10 , wherein the controller is further configured to open the solid-state circuit breaker in response to the fault current.
15. The control device determining that the main switch is closed; modifying the duty cycle of the solid-state switch to disable a current path through the switching network between the first input terminal and the first output terminal; 11. The hybrid circuit protection device of claim 10, further configured to:
16. a current sensor configured to sense the fault current between the first input terminal and the first output terminal; The control device measuring the fault current using the current sensor; determining whether the initial value of the fault current is greater than a threshold; opening the main switch in response to determining that the initial value is greater than the threshold value; 11. The hybrid circuit protection device of claim 10, further configured to:
17. The control device operating the main switch to perform a series of reclosing operations to attempt to clear the fault; modifying the duty cycle of the solid-state switch to current limit the fault current in response to determining that the main switch has performed a final reclosing operation in the series of reclosing operations and that the main switch remains open; 17. The hybrid circuit protection device of claim 16, further configured to:
18. the main switch is configured to perform a series of reclosing operations to attempt to clear the fault; 11. The hybrid circuit protection device of claim 10, wherein the controller is configured to modify the duty cycle of the solid-state switch to current limit the fault current in response to determining that the main switch has performed a final reclosing operation in the series of reclosing operations and that the main switch remains open.
19. 11. The hybrid circuit protection device of claim 10, wherein the main switch comprises 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.
20. The hybrid circuit protection device of claim 1, wherein the solid-state switch comprises one or more insulated gate bipolar transistors, one or more reverse-blocking integrated gate commutation thyristors, one or more silicon carbide metal oxide semiconductor field effect transistors, and / or one or more gallium nitride field effect transistors.