CN113889967A - Topological structure of modular cascade direct current circuit breaker and control method thereof - Google Patents
Topological structure of modular cascade direct current circuit breaker and control method thereof Download PDFInfo
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H3/00—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection
- H02H3/08—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to excess current
- H02H3/087—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to excess current for dc applications
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H3/00—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection
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- H02H3/05—Details with means for increasing reliability, e.g. redundancy arrangements
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Abstract
The invention relates to a topological structure of a modular cascade direct current breaker and a control method thereof, belonging to the technical field of power electronics; the technical problem to be solved is as follows: the improvement of a topological hardware structure of the modular cascade direct current breaker is provided; the technical scheme for solving the technical problems is as follows: a plurality of modularized disjunction sub-modules are cascaded to be used as a main disjunction element of the short-circuit current to carry out disjunction operation on the short-circuit current; the breaking submodule consists of a power device, a plurality of passive elements of a resistor and a capacitor and an auxiliary circuit consisting of diode elements; the cascade mode of the disjunction sub-modules is simple, and the control terminal and the power terminal are directly connected with the corresponding control terminal and the power terminal of the adjacent disjunction sub-modules; the plurality of cascaded breaking submodules form a cascaded breaking substring unit, the breaking action of the substring unit is directly controlled by an external driving unit, the control signals of the submodules are automatically coupled, the dynamic and static voltages are automatically balanced, and the control mode is simple and reliable; the invention is applied to the direct current circuit breaker.
Description
Technical Field
The invention discloses a topological structure of a modular cascade direct current breaker and a control method thereof, and belongs to the technical field of power electronics.
Background
Dc networks have many advantages over ac networks. For example, a direct current power grid is more convenient for large-scale access and application of distributed renewable energy sources. Actually, photovoltaic power generation is direct current power generation, and wind power generation also incorporates alternating current power grid through the form of rectification first and then inversion in reality, and various energy storage modes are also to store electric energy in the form of direct current, if adopt direct current power grid just can realize the direct access of distributed new forms of energy and save the inversion link, have reduced the manufacturing cost of equipment, the loss when also having reduced the contravariant conversion simultaneously. In addition, the direct current power grid is more convenient for the direct use of the electric energy of the power utilization end. At present, most electric equipment at an electric end finally needs direct current, such as charging of an electric automobile, a notebook computer and the like, and electric equipment containing an alternating current motor load also comprises a rectifier and an inverter, so that the use of the rectifier can be reduced through a direct current distribution network, the use quantity of semiconductors is reduced, and the electric energy loss in the rectifying process is also reduced. The direct current power grid is also beneficial to improving the power quality of the power grid, improving the reliability of power supply, improving the power supply capacity and reducing the construction cost of the power grid.
The critical protection equipment required in a dc power grid is the dc circuit breaker, which plays a vital role in fault handling of the dc power grid system and safe and reliable operation of the protection system. In a typical radial dc power distribution system, a large number of dc breakers are required to ensure safe operation of the system. Compared with the traditional alternating current circuit breaker, the development of the direct current circuit breaker faces a great difficulty. In an ac system, a circuit breaker may extinguish an arc using the natural zero crossing of a current cycle, cutting off the fault current. However, in the dc system, there is no zero crossing point of the current, which makes the development of the dc current breaking technology face great technical difficulties. Meanwhile, the direct current system puts higher requirements on the response speed and the breaking speed of the circuit breaker. Since the damping of the dc system is lower than that of the ac system, the rate of rise of the fault current is large after a fault occurs, and the system is required to cut off the fault current in a short time to protect the safety of the system. In addition, the short-circuit current limiting inductor in the direct-current system line can induce a large voltage while switching off the current, and the voltage and the direct-current bus voltage act on the circuit breaker together, so that the voltage is increased sharply. Meanwhile, the short-circuit energy stored in the current-limiting inductor also needs to be exhausted in the breaking time. Compared with a mechanical breaker, the solid-state direct-current breaker adopting the power semiconductor device breaks short-circuit current by utilizing the switching action of the power semiconductor device, and energy absorption devices such as an external lightning arrester absorb short-circuit energy stored on a current-limiting reactance in the short-circuit process, so that the direct-current short-circuit current can be quickly broken by the excellent characteristic, and the direct-current system can be quickly and reliably protected.
At present, the voltage grade of commercial power semiconductor devices is low, the requirements of direct current circuit breakers are difficult to meet, and the voltage-resistant grade of a solid state direct current circuit breaker needs to be improved by adopting a device cascade mode. The driving control scheme of the cascade device in the existing solid-state direct current breaker is complex, each power device needs one set of driving control and power supply system, meanwhile, the voltage of the cascade device is unbalanced due to the physical parameters of the device and the time delay dispersion of the driving circuit, and an additional power end or driving end voltage balancing circuit is needed to guarantee safe operation.
In order to solve the complexity of power device cascade drive and voltage-sharing control in the dc circuit breaker and improve the configuration flexibility of voltage level change, it is necessary to provide a simple and reliable modular dc circuit breaker.
Disclosure of Invention
In order to overcome the defects in the prior art, the invention aims to solve the technical problems that: an improvement of a topological hardware structure of a modular cascade direct current breaker is provided.
In order to solve the technical problems, the invention adopts the technical scheme that: a topological structure of a modular cascade direct current breaker comprises cascade breaking sub-string units, an oscillation suppression unit and a power connection unit, wherein the output ends of the cascade breaking sub-string units are connected with the oscillation suppression unit and then are connected with a positive power terminal of the power connection unit;
the input end of the cascade breaking sub-string unit is connected with an external driving unit, and the driving unit is powered and controlled by a master control system through a control wire harness;
and the negative power terminal of the input end of the cascade breaking sub-string unit is connected with the negative power terminal of the power connection unit.
The cascade breaking sub-string unit consists of n cascaded breaking sub-modules, wherein the breaking sub-module directly connected with the driving unit is an active control module, the rest n-1 breaking sub-modules are driven modules, and n is more than or equal to 2.
The breaking submodules respectively comprise four terminals, wherein the input end comprises a driving terminal and a power terminal, the output end comprises a driving terminal and a power terminal, and the power terminals of two adjacent breaking submodules are connected and the driving terminals are connected;
the power terminal and the driving terminal which are used as the input end of the disjunction submodule of the active control module are respectively connected with the driving unit through leads.
The core element for load current circulation and short circuit current breaking in the breaking submodule is a silicon-based, silicon carbide-based or gallium nitride-based fully-controlled power semiconductor device, the power semiconductor device is connected with a peripheral circuit consisting of a resistor, a capacitor, a diode and a piezoresistor, and the on-off control and dynamic and static voltage balance of the breaking submodule are realized through the peripheral circuit.
The oscillation suppression unit is composed of a group string formed by cascading single or multiple diodes;
and the cathode of a diode in the oscillation suppression unit is connected with the cascade disjunction sub-string unit, and the anode of the diode in the oscillation suppression unit is connected with the anode power terminal of the power connection unit.
A control method of a modularized cascade direct current breaker is characterized in that a power connection unit is used as an external interface and is connected into a direct current system in series, and the control steps of the direct current breaker are as follows;
when the direct current system is in a normal working state, the control unit of the direct current system sends out a high level to control the power semiconductor device in the cascade breaking sub-string unit to be kept on, and load current flows into the solid-state direct current breaker through the anode in the power connection unit and then flows through a power device channel in the cascade breaking sub-string unit;
when the direct current system detects that a short-circuit fault occurs, the master control system sends a turn-off signal to the driving unit, the driving levels at two ends of an output control terminal of the driving unit are changed from high to low, and then the cascade sub-string breaking units are controlled to execute short-circuit current breaking operation;
when the short-circuit energy is completely absorbed, the power semiconductor devices in the cascade breaking sub-string units are in an off state, and the direct-current circuit breaker is in an off state;
when the short-circuit fault is relieved, the driving levels at two ends of an output control terminal of the driving unit are controlled to be changed from low to high by the master control system, the total power devices of the cascade breaking sub-string unit are controlled to be switched on, the load current flows through a diode in the oscillation suppression unit and a power semiconductor device switching-on channel in the cascade breaking sub-string unit, and the direct-current circuit breaker is in a switching-on state.
A control method of a modularized cascade direct current breaker is provided, the direct current breaker is connected with an auxiliary branch circuit composed of a mechanical switch, a first power semiconductor switch and a second power semiconductor switch in parallel to form a hybrid direct current breaker, wherein the structure of the hybrid direct current breaker is as follows: the negative power terminal of the direct current breaker is connected with the second power semiconductor switch in series to serve as a main circuit, the mechanical switch is connected with the first power semiconductor switch in series to serve as a conducting branch circuit, two ends of the main circuit and the conducting branch circuit after being connected in parallel are connected with a direct power transmission and distribution system, and the control steps of the hybrid direct current breaker are as follows;
when the direct current system is in a normal working state, load current flows through a conducting branch circuit formed by the mechanical switch and the first power semiconductor switch, at the moment, a cascade breaking submodule in the direct current breaker topology is in a disconnected state, and the second power semiconductor switch is in a disconnected state;
when a short-circuit fault occurs in the direct-current system, the master control system controls a cascade disjunction submodule in the direct-current circuit breaker topology to be switched on, meanwhile, a second power semiconductor switch is controlled to be switched on, after the direct-current circuit breaker topology and the second power semiconductor switch are completely switched on, a first power semiconductor switch is controlled to be switched off, short-circuit current is transferred to the direct-current circuit breaker topology, after the current transfer is finished, a mechanical switch is switched off, the first power semiconductor switch is switched on, and the hybrid direct-current circuit breaker prepares to disjunction short-circuit current;
and the master control system sends a short-circuit current breaking instruction to the driving unit, and the cascade breaking sub-string units in the direct-current circuit breaker topology execute short-circuit current breaking operation.
Compared with the prior art, the invention has the beneficial effects that: the driving control and the voltage equalization of the modular cascade direct current circuit breaker provided by the invention can be automatically realized through circuits in the sub-modules. The cascaded modules only need to be driven and controlled by an external single driving circuit, and the number of the sub-modules can be determined according to the withstand voltage grade of the selected power device and the voltage grade of the direct-current system. The circuit breaker provided by the invention has the advantages of simple topological structure, low cost, flexible application and high integration level, can realize flexible regulation and control of the DC voltage grade only by simple cascade connection consisting of a small number of passive elements and breaking sub-modules consisting of power devices, greatly reduces the control difficulty, can realize automatic voltage balance when the dynamic and static voltages among the sub-modules are in a turn-off steady state, a turn-on transient state, a turn-on steady state and a turn-off transient state, ensures the safe operation of a short-circuit current breaking core element of the power device, and provides a simple, reliable and low-cost solution for protecting a DC system.
Drawings
The invention is further described below with reference to the accompanying drawings:
fig. 1 is a schematic view of a topology of a dc circuit breaker of the present invention;
FIG. 2 is a schematic circuit structure diagram of a breaking submodule according to the present invention;
fig. 3 is a schematic diagram of a topology of a hybrid dc circuit breaker based on the dc circuit breaker topology of the present invention;
in the figure: p + and N-are power connection terminals in the power connection unit of the direct-current circuit breaker, wherein P + is a positive power terminal, and N-is a negative power single;
df is a diode in the oscillation suppression unit;
the cascaded breaking sub-string unit comprises n cascaded breaking sub-modules, each breaking sub-module comprises four terminals, G1(n) and G2(n) are a first driving terminal and a second driving terminal of the nth breaking sub-module, P (n) and N (n) are a positive power terminal and a negative power terminal of the nth breaking sub-module, G is a gate control terminal of the driving unit, and S is a reference ground of the gate control terminal of the driving unit;
g1 and G2 are respectively a first driving terminal and a second driving terminal of the disjunction submodule of the main control module, and P, N are respectively a positive power terminal and a negative power terminal of the disjunction submodule of the main control module;
m is a power device, and a gate terminal, a drain terminal and a source terminal of the power device are g, d and s respectively;
rs is a damping resistor of the power semiconductor device, and Cs is a damping capacitor of the power semiconductor device;
rg1 and Rg2 are gate driving resistors of the power semiconductor device respectively;
dr is a bypass diode of the gate driving resistor Rg1, Dd is a driving diode, Rstatic is a static voltage-sharing resistor, Cc is a driving coupling capacitor, Var is a piezoresistor, and Zd is a gate voltage-stabilizing diode;
+ is the positive power terminal of the hybrid dc breaker topology, -is the negative power terminal of the hybrid dc breaker.
Detailed Description
As shown in fig. 1 to 3, the dc circuit breaker of the present invention uses a breaking submodule composed of a power semiconductor, a small number of diodes, and a passive element as a core unit, and selects an appropriate number of submodules to cascade according to a voltage class of a dc system to form a cascade breaking substring unit as an actuator to break a short-circuit current. Meanwhile, the hybrid direct current breaker topology is formed by matching the hybrid direct current breaker topology with a power semiconductor and a mechanical switch. The direct current circuit breaker is composed of a master control system, a driving unit, a cascade breaking substring unit, a vibration suppression unit and a power connection unit. The core unit for executing short-circuit current breaking is a cascade breaking sub-string unit, the master control system supplies power and controls the driving unit through a control wire harness, the driving unit drives and controls the cascade breaking sub-string unit through two control wires to carry out breaking operation of direct-current short-circuit current, and driving control and voltage balance in dynamic and static processes of breaking sub-modules in the cascade breaking sub-string unit are completed by an auxiliary circuit consisting of internal diodes and passive elements. The power connection unit is used as an external interface and is connected into the direct current transmission and distribution system in series. In the operation process of the direct-current circuit breaker, the voltage of a power semiconductor device in the cascade disjunction sub-string unit is balanced, and the direct-current can quickly and reliably disjunction the short-circuit current, so that the safe and reliable operation of a direct-current system is guaranteed.
The cascade connection breaking sub-string unit comprises n cascade connection breaking sub-modules, wherein n is determined by the voltage grade of a power semiconductor device in each breaking sub-module and the voltage grade of a direct current system. The breaking submodule (1) directly connected with the driving unit is an active control module, and the rest breaking submodules (n) are driven modules (n-1), wherein n is more than or equal to 2. The disjunction sub-modules are connected with each other by a control line and a power line. The cascade breaking sub-string unit of the direct-current circuit breaker is composed of a plurality of modularized breaking sub-modules. The input and output terminals of the breaking submodule are four, two of the input and output terminals are driving terminals, and the other two input and output terminals are power terminals. And the power terminals of two adjacent breaking submodules are connected, and the driving terminals are connected.
The core element for load current circulation and short circuit current breaking in the breaking sub-module is a silicon-based, silicon carbide-based or gallium nitride-based fully-controlled power semiconductor device (such as MOSFET, IGBT and HEMT), and the power device is connected with a peripheral circuit composed of a resistor, a capacitor, a diode, a piezoresistor and the like. And the on-off control and dynamic and static voltage balance of the sub-modules are realized through a peripheral circuit. In order to improve the current level, the power device in the disjunction submodule can be formed by connecting a plurality of power devices with smaller current levels in parallel.
The oscillation suppression unit is connected between the cascade breaking sub-string unit and the power connection unit, and suppresses voltage oscillation at two ends of the cascade breaking sub-unit after short-circuit current is broken, so that the voltage oscillation is prevented from being coupled to two ends of a breaking sub-module, and further, misoperation of a power device in the sub-module is prevented. The oscillation suppression unit is composed of a group string formed by cascading single or multiple diodes. The number of the cascade diodes is determined by the voltage grade of the direct current system and the voltage-resistant grade of the selected diode. And the cathode of a diode in the oscillation suppression unit is connected with the cascade disjunction sub-string unit, and the anode of the diode in the oscillation suppression unit is connected with the anode power terminal of the power connection unit.
The power end oscillation suppression circuit unit and the driving end oscillation suppression circuit in the main dividing unit act together to suppress the oscillation of the end voltage and the voltage driven by the driven device after the direct-current circuit breaker absorbs the short-circuit energy, so that the driven device is ensured to have stable negative voltage, and the driven device is prevented from being conducted by mistake.
The direct current breaker topology can be matched with the mechanical switch and the power switch to form a hybrid direct current breaker, so that high conduction loss of a sub-module power device in high-voltage power transmission application is avoided.
The control method of the circuit breaker as a solid-state direct current circuit breaker comprises the following steps: the control method is simple, when the line or equipment is in a normal working state, the control unit sends out high level to control the power semiconductor device in the cascade breaking sub-string unit to be kept on, and load current flows into the solid-state direct-current circuit breaker through the anode in the power connection unit and then flows through the power device channel in the cascade breaking sub-string unit. When the system detects that a short-circuit fault occurs, the master control system sends a turn-off signal to the driving unit, the driving levels at two ends of an output control terminal of the driving unit are changed from high to low, and then the cascade sub-string breaking unit is controlled to execute short-circuit current breaking operation. And after the short-circuit energy is completely absorbed, the power semiconductor devices in the cascade breaking sub-string units are in an off state, and the direct-current circuit breaker is in an off state. When the short-circuit fault is relieved, the driving levels at two ends of an output control terminal of the driving unit are controlled to be changed from low to high by the master control system, the total power devices of the cascade breaking sub-string unit are controlled to be switched on, the load current flows through a diode in the oscillation suppression unit and a power semiconductor device switching-on channel in the cascade breaking sub-string unit, and the direct-current circuit breaker is in a switching-on state.
The direct current breaker can be connected with an auxiliary branch circuit consisting of a mechanical switch and a power semiconductor switch in parallel to form a hybrid direct current breaker. The control method comprises the following steps: when the direct current system is in a normal working state, the load current flows through a conducting branch circuit formed by the mechanical switch and the first power semiconductor switch. At the moment, the cascade breaking submodule in the direct current breaker topology is in a breaking state, and the second power semiconductor switch is in a breaking state. When the direct current system has a short-circuit fault, the master control system controls the cascade breaking sub-module in the direct current breaker topology to be switched on, and meanwhile, the second power semiconductor switch is controlled to be switched on. After the direct current breaker topology and the second power semiconductor switch are completely switched on, the power semiconductor 1 is controlled to be switched off, short-circuit current is transferred to the direct current breaker topology, after the current transfer is finished, the mechanical switch is switched off, the first power semiconductor switch is switched on, and the hybrid direct current breaker is ready to break the short-circuit current. And the master control system sends a short-circuit current breaking instruction to the driving unit, and the cascade breaking sub-string units in the direct-current circuit breaker topology execute short-circuit current breaking operation.
As shown in fig. 1, in the dc circuit breaker of the present invention, the power terminal P + in the power connection unit of the dc circuit breaker is connected to the anode terminal of the diode Df in the oscillation suppression unit, and the cathode terminal of the diode Df in the oscillation suppression unit is connected to the anode power terminal P (n) and the second driving terminal G2(n) of the top breaking submodule (n) in the cascade breaking sub-string unit. And a negative power terminal N-in the power connection unit is connected with a negative power terminal N (1) of a breaking submodule (1) in the cascade breaking sub-string unit.
In the cascade breaking sub-string unit, a negative power terminal N (n) of the breaking sub-module (n) is connected with a positive power terminal P (n-1) of the breaking sub-module (n-1), wherein n is more than or equal to 2. The first driving terminal G1(n) of the breaking submodule (n) is connected with the second driving terminal G2 (n-1) of the breaking submodule (n-1), wherein n is larger than or equal to 2. The second driving terminal G2(n) of the dividing submodule (n) is connected to the first driving terminal G1(n + 1) of the dividing submodule (n + 1), wherein n is greater than or equal to 1. And the positive power terminal P (N) of the sub-module (N) is connected with the negative power terminal N (N + 1) of the sub-module (N + 1), wherein N is more than or equal to 1. And the topmost disjunction submodule (n) is the number of cascaded submodules in the cascaded disjunction sub-string units, and the second driving terminal G2(n) is connected with the positive power terminal P (n).
In the cascade connection breaking sub-string unit, a first driving terminal G1 (1) of the breaking sub-module (1) is connected with a gate control terminal G of the driving unit, and a negative power terminal N (1) of the breaking sub-module (1) is connected with a gate control terminal S in the driving unit with reference to the ground.
In the direct current breaker topology, a master control system controls a driving unit through a control wiring harness, and the control wiring harness comprises a power line and a signal line.
As shown in fig. 2, in the dividing submodule, Rs is connected in series with Cs as a snubber circuit, and then connected in parallel with the power semiconductor device M. That is, the upper end of Rs is connected to d of the device M, the lower end of Cs is connected to s of the device M, and the lower end of Rs is connected to the upper end of Cs.
In the breaking submodule, the right end of the Rg2 is connected with a gate g of the device M. The left end of Rg2 is connected to the right end of Rg 1. The left end of Rg1 is connected to the anode of diode Dd. The cathode of the diode Dd is connected to the upper end of the capacitor Cc. The lower end of the capacitor Cc is connected to the source s of the device M. The cathode of the zener diode Zd is connected to the left end of the resistor Rg2, and the anode of the zener diode Zd is connected to the source s of the power device M. The diode Dr is connected in parallel with two ends of the resistor Rg1, namely the anode of the Dr is connected with the right end of the resistor Rg1, and the cathode of the Dr is connected with the left end of the resistor Rg 1. The piezoresistor Var is connected in parallel with two ends of Cc, namely the upper end of Var is connected with the upper end of Cc, and the lower end of Var is connected with the lower end of Cc. The static resistance Rstatic is connected with Var in parallel, namely the upper end of Rstatic is connected with the upper end of Var, and the lower end of Rstatic is connected with the lower end of Var.
As shown in fig. 3, in the hybrid dc breaker topology, the mechanical switch and the first power semiconductor switch are connected in series to form a conducting branch. The left end of the mechanical switch is connected with the positive power terminal + of the hybrid direct-current circuit breaker, the right end of the mechanical switch is connected with the left end of the power semiconductor switch, and the right end of the power semiconductor switch is connected with the negative power terminal of the hybrid direct-current circuit breaker. The positive terminal P + of the DC breaker topology is connected with the left end of the mechanical switch, the negative power terminal N-of the DC breaker topology is connected with the left end of the second power semiconductor switch, and the right end of the power semiconductor switch is connected with the negative power terminal-of the hybrid DC breaker topology.
The invention provides a modular cascade direct current breaker topological structure and a control method thereof. The direct current breaker of the invention uses a plurality of modularized breaking sub-modules to be cascaded as a main breaking element of short-circuit current to carry out breaking operation on the short-circuit current. The breaking submodule consists of a power device, a plurality of passive elements of a resistor and a capacitor and an auxiliary circuit consisting of diode elements. The breaking submodule consists of two power terminals and two control terminals. The submodule cascade mode is simple, and the control terminal and the power terminal are directly connected with the corresponding control terminal and the power terminal of the adjacent disjunction submodule. The plurality of cascaded breaking submodules form a cascaded breaking substring unit, the breaking action of the substring unit is directly controlled by an external driving unit, control signals of the submodules are automatically coupled, dynamic and static voltages are automatically balanced, and the control mode is simple and reliable. In practical engineering application, the number of the cascaded submodules can be flexibly selected according to the voltage grade of the selected power device and the voltage grade of the direct-current system. In the topological structure of the direct current breaker, a power device in a breaking submodule consists of silicon-based, silicon carbide-based or gallium nitride-based full-control devices (such as MOSFET, IGBT and HEMT). The direct current breaker provided by the invention can be matched with a mechanical switch and a power semiconductor switch to form a hybrid direct current breaker topology so as to avoid conduction loss on a cascade power semiconductor device. In conclusion, the circuit breaker provided by the invention has the advantages of simple topological structure, low cost, flexible application and high integration level, can realize flexible regulation and control of the DC voltage grade only by simple cascade connection consisting of a small number of passive elements and breaking sub-modules consisting of power devices, greatly reduces the control difficulty, can realize automatic voltage balance between the sub-modules in the states of switching off, switching on and switching off, ensures the safe operation of a short-circuit current breaking core element of the power device, and provides a simple, reliable and low-cost solution for protecting a DC system.
It should be noted that, regarding the specific structure of the present invention, the connection relationship between the modules adopted in the present invention is determined and can be realized, except for the specific description in the embodiment, the specific connection relationship can bring the corresponding technical effect, and the technical problem proposed by the present invention is solved on the premise of not depending on the execution of the corresponding software program.
Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit the same; while the invention has been described in detail and with reference to the foregoing embodiments, it will be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present invention.
Claims (7)
1. A topological structure of a modular cascade direct current breaker is characterized in that: the cascade breaking substring unit comprises a cascade breaking substring unit, an oscillation suppression unit and a power connection unit, wherein the output end of the cascade breaking substring unit is connected with the oscillation suppression unit and then is connected with the positive power terminal of the power connection unit;
the input end of the cascade breaking sub-string unit is connected with an external driving unit, and the driving unit is powered and controlled by a master control system through a control wire harness;
and the negative power terminal of the input end of the cascade breaking sub-string unit is connected with the negative power terminal of the power connection unit.
2. The topology of a modular cascaded dc circuit breaker of claim 1, wherein: the cascade breaking sub-string unit consists of n cascaded breaking sub-modules, wherein the breaking sub-module directly connected with the driving unit is an active control module, the rest n-1 breaking sub-modules are driven modules, and n is more than or equal to 2.
3. The topology of a modular cascaded dc circuit breaker of claim 2, wherein: the breaking submodules respectively comprise four terminals, wherein the input end comprises a driving terminal and a power terminal, the output end comprises a driving terminal and a power terminal, and the power terminals of two adjacent breaking submodules are connected and the driving terminals are connected;
the power terminal and the driving terminal which are used as the input end of the disjunction submodule of the active control module are respectively connected with the driving unit through leads.
4. The topology of a modular cascaded dc circuit breaker of claim 2, wherein: the core element for load current circulation and short circuit current breaking in the breaking submodule is a silicon-based, silicon carbide-based or gallium nitride-based fully-controlled power semiconductor device, the power semiconductor device is connected with a peripheral circuit consisting of a resistor, a capacitor, a diode and a piezoresistor, and the on-off control and dynamic and static voltage balance of the breaking submodule are realized through the peripheral circuit.
5. The topology of a modular cascaded dc circuit breaker of claim 1, wherein: the oscillation suppression unit is composed of a group string formed by cascading single or multiple diodes;
and the cathode of a diode in the oscillation suppression unit is connected with the cascade disjunction sub-string unit, and the anode of the diode in the oscillation suppression unit is connected with the anode power terminal of the power connection unit.
6. A control method of a modular cascade direct current breaker is characterized in that: the power connection unit is used as an external interface and is connected into a direct current system in series, and the control steps of the direct current circuit breaker are as follows;
when the direct current system is in a normal working state, the control unit of the direct current system sends out a high level to control the power semiconductor device in the cascade breaking sub-string unit to be kept on, and load current flows into the solid-state direct current breaker through the anode in the power connection unit and then flows through a power device channel in the cascade breaking sub-string unit;
when the direct current system detects that a short-circuit fault occurs, the master control system sends a turn-off signal to the driving unit, the driving levels at two ends of an output control terminal of the driving unit are changed from high to low, and then the cascade sub-string breaking units are controlled to execute short-circuit current breaking operation;
when the short-circuit energy is completely absorbed, the power semiconductor devices in the cascade breaking sub-string units are in an off state, and the direct-current circuit breaker is in an off state;
when the short-circuit fault is relieved, the driving levels at two ends of an output control terminal of the driving unit are controlled to be changed from low to high by the master control system, the total power devices of the cascade breaking sub-string unit are controlled to be switched on, the load current flows through a diode in the oscillation suppression unit and a power semiconductor device switching-on channel in the cascade breaking sub-string unit, and the direct-current circuit breaker is in a switching-on state.
7. A control method of a modular cascade direct current breaker is characterized in that: the direct current breaker is connected in parallel with an auxiliary branch circuit consisting of the mechanical switch, the first power semiconductor switch and the second power semiconductor switch to form a hybrid direct current breaker, wherein the structure of the hybrid direct current breaker is as follows: the negative power terminal of the direct current breaker is connected with the second power semiconductor switch in series to serve as a main circuit, the mechanical switch is connected with the first power semiconductor switch in series to serve as a conducting branch circuit, two ends of the main circuit and the conducting branch circuit after being connected in parallel are connected with a direct power transmission and distribution system, and the control steps of the hybrid direct current breaker are as follows;
when the direct current system is in a normal working state, load current flows through a conducting branch circuit formed by the mechanical switch and the first power semiconductor switch, at the moment, a cascade breaking submodule in the direct current breaker topology is in a disconnected state, and the second power semiconductor switch is in a disconnected state;
when a short-circuit fault occurs in the direct-current system, the master control system controls a cascade disjunction submodule in the direct-current circuit breaker topology to be switched on, meanwhile, a second power semiconductor switch is controlled to be switched on, after the direct-current circuit breaker topology and the second power semiconductor switch are completely switched on, a first power semiconductor switch is controlled to be switched off, short-circuit current is transferred to the direct-current circuit breaker topology, after the current transfer is finished, a mechanical switch is switched off, the first power semiconductor switch is switched on, and the hybrid direct-current circuit breaker prepares to disjunction short-circuit current;
and the master control system sends a short-circuit current breaking instruction to the driving unit, and the cascade breaking sub-string units in the direct-current circuit breaker topology execute short-circuit current breaking operation.
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| CN106159882A (en) * | 2016-07-13 | 2016-11-23 | 西安交通大学 | A kind of solid-state direct-current chopper based on SiC MOSFET and control method thereof |
| CN109066609A (en) * | 2018-07-26 | 2018-12-21 | 西安交通大学 | A kind of all solid state dc circuit breaker topological structure based on cascade SiC MOSFET |
| CN111509677A (en) * | 2020-04-03 | 2020-08-07 | 全球能源互联网研究院有限公司 | Full-bridge module and direct current circuit breaker |
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| CN106159882A (en) * | 2016-07-13 | 2016-11-23 | 西安交通大学 | A kind of solid-state direct-current chopper based on SiC MOSFET and control method thereof |
| CN109066609A (en) * | 2018-07-26 | 2018-12-21 | 西安交通大学 | A kind of all solid state dc circuit breaker topological structure based on cascade SiC MOSFET |
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