Passive semi-control hybrid direct current breaker and control method thereof
Technical Field
The invention relates to the technical field of power electronics, in particular to a passive semi-controlled hybrid direct-current circuit breaker and a control method thereof.
Background
Wind and light and other large-scale clean energy sources are connected to the grid and consumed to provide requirements for the development of a direct current transmission and distribution system, and the high-voltage direct current breaker is a key device for reliable, economic and flexible operation of the direct current system. The direct current circuit breaker which adopts the mechanical switch and the power electronic device in a mixed mode has the low loss characteristic of the mechanical switch and the quick breaking characteristic of the power electronic device, and is the most effective technical approach for realizing quick current breaking in the current direct current system. At present, a hybrid direct current circuit breaker generally adopts a full-control device, the on-off current is limited by the on-off current capability of the full-control device, the cost is relatively high, and the hybrid direct current circuit breaker is limited to be widely popularized and applied in a weak-damping direct current power transmission and distribution system.
Although the hybrid direct current breaker based on the thyristor in the prior art can obviously improve the on-off current capability of the direct current breaker, the thyristor cannot be turned off automatically, and the internal current transfer of the direct current breaker needs to be realized by passive elements such as capacitors and reactances which are pre-stored. The internal current transfer of the direct current circuit breaker can be realized by the energy supply system in a capacitor pre-charging mode, but the loss and the cost of the direct current circuit breaker are high, the size is large, and the overall reliability of the direct current circuit breaker is low.
Disclosure of Invention
In order to overcome the defects of high loss, large volume, high cost and low overall reliability in the prior art, the invention provides a passive semi-controlled hybrid direct-current circuit breaker and a control method thereof, wherein the direct-current circuit breaker comprises a quick mechanical switch K, a resonance module, an energy consumption branch circuit for absorbing fault current, a thyristor T1 and a thyristor T2; two ends of the rapid mechanical switch K are respectively connected with a direct current circuit to form a main through-current branch; the thyristor T1 and the thyristor T2 are connected in series with the resonance module after being connected in anti-parallel to form a transfer branch circuit; the transfer branch and the energy consumption branch are connected with the main through-flow branch in parallel; and the collector electrode of the thyristor T1 is connected with the quick mechanical switch K, so that the loss is greatly reduced, the volume is reduced, the cost is reduced, and the overall reliability is improved.
In order to achieve the purpose of the invention, the invention adopts the following technical scheme:
on one hand, the invention provides a passive semi-controlled hybrid direct current circuit breaker, which comprises a quick mechanical switch K, a resonance module, an energy consumption branch circuit for absorbing fault current, a thyristor T1 and a thyristor T2, wherein the quick mechanical switch K is connected with the resonance module through a power supply;
two ends of the rapid mechanical switch K are respectively connected with a direct current circuit to form a main through-current branch;
the thyristor T1 and the thyristor T2 are connected in series with the resonance module after being connected in anti-parallel to form a transfer branch circuit;
the transfer branch and the energy consumption branch are connected with the main through-flow branch in parallel;
and the collector of the thyristor T1 is connected with a fast mechanical switch K.
The resonance module comprises a capacitor C and an inductor L;
the capacitor C, the inductor L and the thyristor T1/T2 are sequentially connected in series.
The transfer branch circuit further comprises a resistor R; one end of the resistor R is connected between the inductor L and the thyristor T1/the thyristor T2, and the other end of the resistor R is grounded.
The energy consumption branch comprises one or more lightning arresters connected in series.
In another aspect, the present invention provides a method for controlling a passive semi-controlled hybrid dc circuit breaker, including:
when the direct current breaker is put into operation, the quick mechanical switch K is controlled to be switched on, and the normal working current of a direct current line flows through the main through-current branch;
when the line side of the direct current breaker breaks down, the fast mechanical switch K is controlled to be switched off, then the thyristor T2 and the thyristor T1 are triggered in sequence, and then the energy consumption branch absorbs fault current; (ii) a
When the power supply side of the direct current breaker breaks down, the quick mechanical switch K is controlled to be switched off, the thyristor T2 is triggered, and then the energy consumption branch absorbs fault current.
When the direct current circuit breaker is put into operation, the quick mechanical switch K is controlled to be closed, and before the normal working current of a direct current circuit flows through the main through-current branch, the method comprises the following steps:
charging capacitor C, thyristor T1 and thyristor T2 are both latched.
When direct current circuit breaker line side broke down, control quick mechanical switch K separating brake, then triggered thyristor T2 and thyristor T1 in proper order, later the energy consumption branch road absorbs fault current, include:
when the direct current breaker receives a switching-off command or reaches an overcurrent protection fixed value, controlling a quick mechanical switch K to switch off;
triggering the thyristor T2 to discharge the capacitor C;
after the capacitor C oscillates reversely, the thyristor T1 is triggered to charge the capacitor C;
and when the voltage of the capacitor C reaches the action voltage of the energy consumption branch circuit, the energy consumption branch circuit absorbs fault current.
When direct current circuit breaker power supply side breaks down, control quick mechanical switch K and break off, trigger thyristor T2, later the energy consumption branch road absorbs fault current, include:
when the direct current breaker receives a switching-off command or reaches an overcurrent protection fixed value, controlling the quick mechanical switch K to open;
triggering the thyristor T2 to discharge the capacitor C;
after the current of the quick mechanical switch K is cut off, the capacitor C is charged;
and when the voltage of the capacitor C reaches the action voltage of the energy consumption branch circuit, the energy consumption branch circuit absorbs fault current.
Compared with the closest prior art, the technical scheme provided by the invention has the following beneficial effects:
the passive semi-controlled hybrid direct-current circuit breaker comprises a quick mechanical switch K, a resonance module, an energy consumption branch circuit for absorbing fault current, a thyristor T1 and a thyristor T2; two ends of the rapid mechanical switch K are respectively connected with a direct current circuit to form a main through-current branch; the thyristor T1 and the thyristor T2 are connected in series with the resonance module after being connected in anti-parallel to form a transfer branch circuit; the transfer branch and the energy consumption branch are connected with the main through-flow branch in parallel; the collector electrode of the thyristor T1 is connected with a quick mechanical switch K, so that the loss is greatly reduced, the volume is reduced, the cost is reduced, and the overall reliability is improved;
the direct-current circuit breaker provided by the invention can realize bidirectional and rapid on-off of direct current, has low operation loss, the main through-current branch is only composed of a rapid mechanical switch, the topological on-state loss of the direct-current circuit breaker is negligible, a water cooling system is not required to be configured, the direct-current circuit breaker has strong overload capacity, the on-off current can reach dozens of kA, and the application requirement of a direct-current power transmission and distribution system is met;
the direct current breaker provided by the invention has small design and integration difficulty, mainly adopts a semi-controlled power electronic device, has mature technology and lower cost, and can obviously improve the economy of the direct current breaker;
the invention does not need to be provided with a high-voltage isolation auxiliary power supply, simplifies the structure of the equipment, improves the reliability and effectively reduces the occupied area of the equipment.
Drawings
Fig. 1 is a topological structure diagram of a passive semi-controlled hybrid dc circuit breaker according to an embodiment of the present invention;
FIG. 2 is a schematic diagram of the quick mechanical switch K not closing when the DC circuit breaker is put into operation according to the embodiment of the invention;
FIG. 3 is a schematic diagram of a fast mechanical switch K switching on when the DC circuit breaker is put into operation according to the embodiment of the invention;
FIG. 4 is a schematic diagram of the fast mechanical switch K opening when the line side fails according to the embodiment of the invention;
FIG. 5 is a schematic diagram of the discharge of a capacitor in the event of a line side fault in an embodiment of the present invention;
FIG. 6 is a schematic diagram of a thyristor triggered after a capacitor oscillation reverses direction when a line side fails according to an embodiment of the present invention;
FIG. 7 is a schematic diagram of capacitor charging in the event of a line side fault in an embodiment of the present invention;
FIG. 8 is a schematic diagram of the energy consuming branch absorbing fault current when a line side fails in an embodiment of the present invention;
FIG. 9 is a schematic diagram of the fast mechanical switch K opening when the power supply side fails according to an embodiment of the present invention;
FIG. 10 is a schematic diagram of the capacitor discharge when the power supply side fails in the embodiment of the present invention;
FIG. 11 is a schematic diagram illustrating the charging of a capacitor when a power supply side fails according to an embodiment of the present invention;
fig. 12 is a schematic diagram of the energy consumption branch absorbing fault current when the power supply side fails in the embodiment of the present invention.
Detailed Description
The present invention will be described in further detail with reference to the accompanying drawings.
The embodiment of the invention provides a passive semi-controlled hybrid direct-current circuit breaker, which is arranged on a direct-current circuit, wherein the specific topological structure is shown in figure 1, and the passive semi-controlled hybrid direct-current circuit breaker comprises a quick mechanical switch K, a resonance module, an energy consumption branch circuit for absorbing fault current, a thyristor T1 and a thyristor T2;
two ends of the quick mechanical switch K are respectively connected with a direct current circuit to form a main through-current branch;
the thyristor T1 and the thyristor T2 are connected in series with the resonance module after being connected in anti-parallel to form a transfer branch circuit;
the transfer branch and the energy consumption branch are connected with the main through-flow branch in parallel;
and the collector of thyristor T1 is connected to a fast mechanical switch K.
The resonance module comprises a capacitor C and an inductor L;
the capacitor C, the inductor L and the thyristor T1/T2 are sequentially connected in series.
The transfer branch circuit also comprises a resistor R; one end of the resistor R is connected between the inductor L and the thyristor T1/the thyristor T2, and the other end is grounded. Since the thyristor T1 and the thyristor T2 are connected in anti-parallel, when the collector of the thyristor T1 is connected to the fast mechanical switch K, the emitter of the thyristor T2 is connected to the fast mechanical switch K.
The energy consumption branch comprises one or more lightning arresters connected in series.
Example 2
The embodiment 2 of the invention provides a control method of a passive semi-controlled hybrid direct-current circuit breaker, the passive semi-controlled hybrid direct-current circuit breaker is divided into three working conditions of operation (namely normal operation), line side failure and power supply side failure, and the specific control method comprises the following steps:
when the direct current breaker is put into operation, the fast mechanical switch K is controlled to be switched on, and the direct current line current i flows through the main through-current branch circuit, as shown in fig. 3;
when the line side of the direct current breaker breaks down, the fast mechanical switch K is controlled to be switched off, then the thyristor T2 and the thyristor T1 are triggered in sequence, and then the energy consumption branch absorbs fault current;
when the power supply side of the direct current breaker breaks down, the quick mechanical switch K is controlled to be switched off, the thyristor T2 is triggered, and then the energy consumption branch absorbs fault current.
When the direct current circuit breaker is put into operation, the fast mechanical switch K is controlled to be closed, before the direct current line current flows through the main through-current branch circuit, the fast mechanical switch K is not switched on, the capacitor C is charged through a loop formed by the capacitor C, the inductor L, the resistor R and the ground, and the thyristor T1 and the thyristor T2 are both locked, as shown in fig. 2.
When direct current circuit breaker line side broke down, control quick mechanical switch K separating brake, then triggered thyristor T2 and thyristor T1 in proper order, later the energy consumption branch road absorbs fault current, include:
when the direct current breaker receives a switching-off command or reaches an overcurrent protection fixed value, controlling the quick mechanical switch K to open as shown in figure 4;
after the rapid mechanical switch K is opened to a sufficient opening distance, the thyristor T2 is triggered, the capacitor C discharges through a loop formed by the rapid mechanical switch K, the thyristor T2 and the inductor L, and the main branch current is superposed with the oscillation current iLCAs shown in fig. 5;
after the capacitor C oscillates reversely, the thyristor T1 is triggered, and the main branch current is superposed with a reverse oscillation current iLCAs shown in fig. 6, a current zero crossing point is created, and the arc of the fast mechanical switch K is extinguished; the fault current charges the capacitor C, and the voltage of the capacitor CElevated, as shown in fig. 7;
when the voltage of the capacitor C reaches the action voltage of the energy consumption branch, the fault current commutates to the energy consumption branch, and the energy consumption branch absorbs the fault current and completes the fault current breaking, as shown in fig. 8.
When direct current circuit breaker power supply side breaks down, control quick mechanical switch K and break off, trigger thyristor T2, later the energy consumption branch road absorbs fault current, include:
when the direct current breaker receives a switching-off command or reaches an overcurrent protection fixed value, controlling the quick mechanical switch K to open as shown in FIG. 9;
after the rapid mechanical switch K is opened to a sufficient opening distance, the thyristor T2 is triggered, the capacitor C discharges through a loop formed by the rapid mechanical switch K, the thyristor T2 and the inductor L, and the main branch current is superposed with the reverse oscillation current iLCAs shown in fig. 10, a current zero crossing is created and the arc is extinguished;
after the current of the fast mechanical switch K is disconnected, the fault current is transferred to the transfer branch circuit to charge the capacitor C, and the voltage of the capacitor C is increased, as shown in fig. 11;
when the voltage of the capacitor C reaches the operating voltage of the energy consumption branch, the fault current commutates to the energy consumption branch, and the energy consumption branch absorbs the fault current and completes the fault current breaking, as shown in fig. 12.
Finally, it should be noted that: the above embodiments are only intended to illustrate the technical solution of the present invention and not to limit the same, and a person of ordinary skill in the art can make modifications or equivalents to the specific embodiments of the present invention with reference to the above embodiments, and such modifications or equivalents without departing from the spirit and scope of the present invention are within the scope of the claims of the present invention as set forth in the claims.