CN114421477A - Low-voltage capacitor high-speed switching compensation module and control method thereof - Google Patents
Low-voltage capacitor high-speed switching compensation module and control method thereof Download PDFInfo
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- CN114421477A CN114421477A CN202111602978.1A CN202111602978A CN114421477A CN 114421477 A CN114421477 A CN 114421477A CN 202111602978 A CN202111602978 A CN 202111602978A CN 114421477 A CN114421477 A CN 114421477A
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/01—Arrangements for reducing harmonics or ripples
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J13/00—Circuit arrangements for providing remote indication of network conditions, e.g. an instantaneous record of the open or closed condition of each circuitbreaker in the network; Circuit arrangements for providing remote control of switching means in a power distribution network, e.g. switching in and out of current consumers by using a pulse code signal carried by the network
- H02J13/00006—Circuit arrangements for providing remote indication of network conditions, e.g. an instantaneous record of the open or closed condition of each circuitbreaker in the network; Circuit arrangements for providing remote control of switching means in a power distribution network, e.g. switching in and out of current consumers by using a pulse code signal carried by the network characterised by information or instructions transport means between the monitoring, controlling or managing units and monitored, controlled or operated power network element or electrical equipment
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J13/00—Circuit arrangements for providing remote indication of network conditions, e.g. an instantaneous record of the open or closed condition of each circuitbreaker in the network; Circuit arrangements for providing remote control of switching means in a power distribution network, e.g. switching in and out of current consumers by using a pulse code signal carried by the network
- H02J13/00032—Systems characterised by the controlled or operated power network elements or equipment, the power network elements or equipment not otherwise provided for
- H02J13/00036—Systems characterised by the controlled or operated power network elements or equipment, the power network elements or equipment not otherwise provided for the elements or equipment being or involving switches, relays or circuit breakers
- H02J13/0004—Systems characterised by the controlled or operated power network elements or equipment, the power network elements or equipment not otherwise provided for the elements or equipment being or involving switches, relays or circuit breakers involved in a protection system
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/12—Circuit arrangements for ac mains or ac distribution networks for adjusting voltage in ac networks by changing a characteristic of the network load
- H02J3/16—Circuit arrangements for ac mains or ac distribution networks for adjusting voltage in ac networks by changing a characteristic of the network load by adjustment of reactive power
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/18—Arrangements for adjusting, eliminating or compensating reactive power in networks
- H02J3/1821—Arrangements for adjusting, eliminating or compensating reactive power in networks using shunt compensators
- H02J3/1835—Arrangements for adjusting, eliminating or compensating reactive power in networks using shunt compensators with stepless control
- H02J3/1864—Arrangements for adjusting, eliminating or compensating reactive power in networks using shunt compensators with stepless control wherein the stepless control of reactive power is obtained by at least one reactive element connected in series with a semiconductor switch
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E40/00—Technologies for an efficient electrical power generation, transmission or distribution
- Y02E40/30—Reactive power compensation
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E40/00—Technologies for an efficient electrical power generation, transmission or distribution
- Y02E40/40—Arrangements for reducing harmonics
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Abstract
The invention belongs to the field of low-voltage capacitor switching compensation, and provides a low-voltage capacitor high-speed switching compensation module and a control method thereof. The compensation module comprises a circuit breaker, a switching switch, a reactor, a capacitor and a module control board; a digital phase locking unit and an inrush current-free switching logic unit are arranged on the module control panel; the digital phase-locking unit is used for locking the phase of the three-phase voltage of the power grid; the inrush current-free switching logic unit is used for finding the peak point moment of the three-phase voltage of the power grid after phase locking, and triggering a switching switch at the peak point of the three-phase voltage of the power grid and putting the switching switch into a capacitor after receiving an external input command; the switching-on/off part is composed of a silicon controlled rectifier and a diode which are connected in anti-parallel; when the silicon controlled rectifier in the fling-cut switch is turned off, the capacitor is charged through the diode, and the capacitor is charged to the voltage when the line voltage is peak when the diode is turned off, namely the fling-cut switch is turned off, so that the aim of high-speed fling-cut can be achieved by waiting for re-responding to fling-cut instructions.
Description
Technical Field
The invention belongs to the field of low-voltage capacitor switching compensation, and particularly relates to a low-voltage capacitor high-speed switching compensation module and a control method thereof.
Background
The statements in this section merely provide background information related to the present disclosure and may not necessarily constitute prior art.
The traditional synchronous triggering mode of the capacitance compensation of silicon controlled rectifier switching mainly adopts the zero-crossing detection of the voltage of the silicon controlled rectifier terminal or the zero-crossing phase-locking detection of the power voltage. When the capacitor of the series reactor is switched by the silicon controlled rectifier terminal voltage zero-crossing detection mode, the capacitor can be switched again after being cut off after a certain discharge time, so that the problem of slow response time or short-time phase-lacking operation is caused. When high-power impact load or a phase-change short circuit process of phase-control rectifying equipment occurs, large voltage drop can occur, so that zero-crossing phase-locking detection of power supply voltage is wrong; in the situation of large industrial load harmonic wave, the zero-crossing phase-locked detection of the power supply voltage can be wrong due to the influence of the harmonic wave.
The attenuation of compensating branch circuit condenser and the excessive problem of branch circuit current harmonic can not be judged in traditional capacitance compensation, and the attenuation of electric capacity can lead to the reactance rate to descend absorptive harmonic can the grow, and the long-term excessive of current harmonic in the compensation return circuit can lead to electric capacity to generate heat and accelerate the damage, and then the accident that the electric capacity bursts can appear. The traditional capacitance compensation is protected by utilizing a fuse or a circuit breaker with branch circuits connected In series, because the selection of the protection current is generally larger and is more than 1.43In according to the national standard, when the external devices are protected, the faults are enlarged, and the protection of the devices at the initial stage of damage and the prevention of accidents cannot be realized.
In a traditional capacitance compensation device switched by the silicon controlled rectifier, the breakdown voltage of the silicon controlled rectifier is reduced along with factors such as aging, and the breakdown voltage of the silicon controlled rectifier is insufficient due to the overvoltage of a power grid, so that the silicon controlled rectifier can be switched on or off automatically at a certain critical point after the breakdown voltage is reduced. The problem of unbalance or compensation error is often caused under the condition that the silicon controlled rectifier is broken down and conducted; under the condition that breakdown voltage of the silicon controlled rectifier is reduced and the silicon controlled rectifier is automatically switched on and off in a critical state, inrush current can be generated to damage a capacitor, when effective value current cannot reach the protection value of an external protection device, faults can be continuously enlarged, when the external protection device is protected, accidents are large, and the accidents of capacitor explosion can often occur. Therefore, the traditional capacitance compensation branch circuit cannot timely carry out the branch circuit cutting protection at the initial stage of the fault under the condition that the silicon controlled rectifier is out of control due to breakdown conduction or breakdown voltage reduction and critical automatic on-off.
Disclosure of Invention
In order to solve the problems, the invention provides a low-voltage capacitor high-speed switching compensation module and a control method thereof, wherein a main loop adopts a corner internal connection method formed by serially connecting a switching switch, a reactor and a capacitor, wherein the switching switch is formed by connecting a diode and a silicon controlled rectifier in an anti-parallel mode, the capacitor can be charged to the voltage when the line voltage is peak when the capacitor is not switched or the capacitor is cut off, a module control panel of the compensation module realizes the phase locking of the voltage of a power grid by using a digital phase locking technology, the compensation module can be free from the influence of harmonic waves and voltage drops, the moment of the voltage peak point of the power grid line can be accurately found, three silicon controlled rectifiers of the switching switch are respectively triggered at the three line voltage peak points of the power grid after an external input command is received, the three silicon controlled rectifiers can be switched into the capacitor without inrush current, and can be immediately switched again after the capacitor is cut off, the problem that the capacitor compensation adopts slow switching response time of the zero-crossing detection of the voltage of the silicon controlled rectifiers and the synchronous triggering mode of the zero-crossing detection of the power supply voltage is easily subjected to harmonic waves The influence of voltage drop is affected, and the method is suitable for occasions with large harmonic waves and rapid reactive fluctuation with voltage drop impact.
In order to achieve the purpose, the invention adopts the following technical scheme:
the invention provides a high-speed switching compensation module for a low-voltage capacitor.
A high-speed switching compensation module for a low-voltage capacitor comprises a circuit breaker, a switching switch, a reactor, a capacitor and a module control board, wherein the switching switch, the reactor and the capacitor are connected in series to form an inner triangle and are connected to the outlet side of the circuit breaker in parallel, and the inlet side of the circuit breaker is connected with a power supply;
the module control panel is provided with a digital phase locking unit and a no-inrush current switching logic unit; the digital phase-locking unit is used for locking the phase of the three-phase voltage of the power grid; the inrush current-free switching logic unit is used for finding the peak point moment of the three-phase line voltage of the power grid after phase locking, and triggering a switching switch at the peak point of the three-phase line voltage of the power grid after receiving an external input command so that the switching switch can be input into a capacitor without inrush current;
the switching switch is composed of a silicon controlled rectifier and a diode which are connected in anti-parallel; when the silicon controlled rectifier in the fling-cut switch is turned off, the capacitor is charged through the diode, and when the diode is turned off, namely the fling-cut switch is turned off, the capacitor is charged to the voltage when the line voltage is at the peak value.
Furthermore, the input end of the inrush current-free switching logic unit receives the phase signal and the phase sequence signal of the power grid after digital phase locking, the inrush current-free switching logic unit is used for switching an inrush current-free input phase point according to the phase sequence signal of the power grid, and when the actual phase is consistent with the inrush current-free input phase point, a trigger signal of a thyristor in a corresponding switching switch is output to input the thyristor into the capacitor.
Furthermore, the module control board is also provided with a capacitance attenuation protection unit, the input end of the capacitance attenuation protection unit is connected with the voltage of the power grid, the compensation current and the voltage frequency after digital phase locking, the capacitance value of the capacitor is calculated by combining the actual reactance rate and the capacitance value of the capacitor nameplate in an online simulation mode, the attenuation rate of the capacitor is calculated, and when the attenuation rate of the capacitor exceeds a set value, an alarm shutdown signal is output.
Furthermore, the module control panel is also provided with a harmonic protection unit, the input end of the harmonic protection unit is connected with the power grid voltage and the compensation current, a fundamental wave value and a harmonic value are calculated according to the sampled power grid voltage and the compensation current, the harmonic content of the power grid voltage and the harmonic content of the compensation current are respectively calculated, and an alarm shutdown signal is output when the harmonic content exceeds the respective set protection value.
Furthermore, a silicon controlled breakdown protection unit is further arranged on the module control panel, the input end of the silicon controlled breakdown protection unit receives the trigger instruction and the compensation current, the state of the silicon controlled is obtained according to the trigger instruction and the compensation current, and a tripping signal is output to a tripping coil of the circuit breaker after breakdown is found.
Furthermore, the module control panel is also provided with a full-duplex communication unit, the full-duplex communication unit is provided with a full-duplex communication interface, and receives a high-speed switching communication instruction of an external controller in a broadcast instruction interception mode and sends the state information of the module control panel in a full-duplex mode.
Furthermore, the module control panel is also provided with a temperature protection unit which is used for sampling the temperature of the capacitor, the temperature of the reactor, the temperature of the radiator on the switching switch and the ambient temperature, the temperature protection unit is used for calculating the temperature or the temperature rise of the radiator on the capacitor, the reactor and the switching switch, and when the temperature or the temperature rise of the radiator on the capacitor, the reactor and the switching switch exceeds a set protection value, an alarm shutdown signal is output.
Furthermore, the low-voltage capacitor high-speed switching compensation module also comprises three current transformers, wherein the primary sides of the three current transformers are respectively connected in series in three corner inner loops of a triangular connection method, and the secondary sides of the three current transformers are respectively connected with three current input ends of the module control board.
Further, the circuit breaker is provided with a tripping coil, and the control end of the tripping coil is connected to a tripping wiring terminal of the module control panel.
Furthermore, a radiator is further arranged on the throw-open switch, a temperature sensor is mounted on the radiator, and the temperature sensor is connected to a radiator temperature wiring terminal of the module control board.
Furthermore, the reactor is composed of three windings, each winding is provided with an independent wire inlet end and an independent wire outlet end, and each winding is provided with a temperature measuring sensor which is respectively connected to a reactance temperature wiring terminal of the module control board.
Furthermore, the capacitor is composed of three groups of independent single-phase capacitors, each group of capacitors is provided with a wire inlet end and a wire outlet end, each group of capacitors is provided with a temperature measuring sensor, and the temperature measuring sensors are respectively connected to the capacitance temperature wiring terminals of the module control board.
Further, the digital phase locking unit includes:
the three AD conversion units are used for respectively converting the three-phase voltage analog signals of the power grid into digital signals;
the first adder and the second adder are used for respectively subtracting the A-phase voltage digital signal and the C-phase voltage digital signal from the B-phase voltage digital signal;
the first proportional regulator is connected with the output end of the first adder;
the second proportional regulator is connected with the output end of the second adder;
one input end of the first multiplier is connected with the first proportional regulator, the other input end of the first multiplier is connected with the output end of the first sine operator, and the input end of the first sine operator is connected with the output end of the integrator with the reset end;
one input end of the second multiplier is connected with the second proportional regulator, the other input end of the second multiplier is connected with the output end of the second sine operator, the input end of the second sine operator is connected with a fourth adder, and two input ends of the fourth adder are respectively connected with the output end of the integrator at the reset end and a first constant;
a third adder for adding the output results of the first multiplier and the second multiplier;
the low-pass filter is used for filtering harmonic signals, and the input end of the low-pass filter is connected with the output end of the third adder;
the input end of the PI regulator is connected with the output end of the low-pass filter, the output end of the PI regulator is connected with the input end of a second absolute value arithmetic unit, and the output end of the second absolute value arithmetic unit is an angular frequency signal;
the input end of the third proportional regulator is connected with the output end of the PI regulator;
one input end of the integrator with the reset end is connected with the output end of the third proportional regulator, and the other input end of the integrator with the reset end is connected with the output end of the comparator;
and the positive input end of the comparator is connected with the output end of the first absolute value operator, the input end of the first absolute value operator is connected with the output end of the integrator with the reset end, and the negative input end of the comparator is connected with the second constant.
The invention provides a control method of a low-voltage capacitor high-speed switching compensation module.
A control method for a low-voltage capacitor high-speed switching compensation module comprises the following steps:
the method comprises the steps that the three-phase voltage of a digital phase-locked power grid obtains the phase sequence and the phase of the power grid voltage;
when the compensation module receives an external input command, the phase is judged according to the phase sequence of the power grid voltage, the moment of the positive peak point of the three-phase line voltage of the power grid is found, and the silicon controlled instructions for triggering the switching switch are sent out at the positive peak point of the three-phase line voltage of the power grid respectively to input the silicon controlled instructions into the capacitor;
after the compensation module receives an external cutting command, the phase is judged according to the current power grid voltage phase sequence, the moment of the positive zero crossing point of the power grid three-phase line voltage (namely the line voltage is directly opposite to the current of a diode in a corresponding fling-cut switch from negative change and is taken as the peak value) is found, the silicon controlled rectifier instruction for stopping triggering the fling-cut switch is respectively sent, the silicon controlled rectifier is naturally cut off at the zero current position, then the diode is switched on and is cut off after half power frequency period, the capacitor cutting is completed, at the moment, three groups of capacitors are fully charged through the diodes respectively, and the compensation module can immediately respond the external cutting command to enable the capacitors to be cut again so as to achieve the purpose of high-speed switching.
Compared with the prior art, the invention has the beneficial effects that:
(1) the digital phase-locking unit is used for phase-locking the three-phase voltage of the power grid, the reliability of the phase-locking synchronous triggering technology can be improved, the inrush current-free switching logic unit is used for finding the moment of the positive peak point of the three-phase line voltage of the power grid, and the switching switch is triggered at the positive peak point of the three-phase line voltage of the power grid and is switched into the capacitor after an external input command is received, so that the problem that the response time of the thyristor terminal voltage zero-crossing detection for the capacitance compensation of thyristor switching is slow, and the synchronous triggering mode of the power supply voltage zero-crossing phase-locking detection is easily influenced by harmonic waves and voltage drops, and the method can be suitable for the occasions with large harmonic waves and rapid reactive fluctuation of voltage drop impact.
(2) The switching switch of the invention is composed of a silicon controlled rectifier and a diode which are connected in anti-parallel; when an external cutting command is received, the switching switch is stopped to be triggered at the positive zero crossing point (namely the positive peak current of the diode) of the three-phase line voltage of the power grid after phase locking, so that the problem that the switching switch is slowly turned off due to the fact that the diode delays to turn on the half-cycle waveguide caused by harmonic waves when the silicon controlled rectifier stops triggering near the fundamental zero current can be avoided; when the silicon controlled rectifier in the switching switch stops triggering, the switching switch is naturally turned off at a zero current position, then the capacitor is fully charged through a diode in the switching switch after a half power frequency period, and the switching instruction can be responded again immediately at the moment, so that the aim of high-speed switching can be fulfilled.
(3) According to the invention, the capacitance value attenuation protection unit, the harmonic protection unit, the silicon control breakdown protection unit and the temperature protection unit are also arranged on the module control panel, so that the problem of monitoring and protection at the initial stage of the fault of the capacitor compensation branch circuit is solved, and the expansion of the accident can be avoided.
(4) The digital phase-locking unit of the invention is composed of hardware logic devices, thereby avoiding digital phase-locking programming and simultaneously improving the reliability of the digital phase-locking synchronous triggering technology.
Drawings
The accompanying drawings, which are incorporated in and constitute a part of this specification, are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification, illustrate exemplary embodiments of the invention and together with the description serve to explain the invention and not to limit the invention.
Fig. 1 is a schematic structural diagram of a low-voltage capacitor high-speed switching compensation module according to an embodiment of the present invention;
FIG. 2 is a functional block diagram of a digital phase lock unit of an embodiment of the present invention;
fig. 3 is a flow chart of inrush current free switching logic unit according to an embodiment of the present invention.
Detailed Description
The invention is further described with reference to the following figures and examples.
It is to be understood that the following detailed description is exemplary and is intended to provide further explanation of the invention as claimed. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.
It is noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of exemplary embodiments according to the invention. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, and it should be understood that when the terms "comprises" and/or "comprising" are used in this specification, they specify the presence of stated features, steps, operations, devices, components, and/or combinations thereof, unless the context clearly indicates otherwise.
Interpretation of terms:
the low voltage in the low-voltage capacitance high-speed switching compensation module refers to AC 1140V and below.
As shown in fig. 1, the low-voltage capacitor high-speed switching compensation module of this embodiment includes a circuit breaker (1), a switching switch (3), a reactor (4), a capacitor (5) and a module control board (6), the switching switch (3), the reactor (4) and the capacitor (5) are connected in series to form an inner triangle and connected to the outlet side of the circuit breaker (1), and the inlet side of the circuit breaker (1) is connected to a power supply;
the module control board (6) is provided with a digital phase locking unit and a no-inrush current switching logic unit; when the circuit breaker (1) is closed, the whole low-voltage capacitor high-speed switching compensation module is connected with a power supply, the module control panel (6) is used for sampling three-phase voltage of a power grid, after phase locking is carried out by a digital phase locking unit, the moment of a positive peak point of the three-phase line voltage of the power grid is found by a no-inrush current switching logic unit, and after an external controller input command is received, the switching switch (3) is triggered at the positive peak point of the three-phase line voltage of the power grid and is input into the capacitor (5); when the silicon controlled rectifier in the switching switch (3) is turned off, the capacitor (5) is charged through the diode, when the diode is turned off, namely the switching switch (3) is turned off, the capacitor (5) is charged to the voltage when the line voltage is peak, and at the moment, the switching instruction can be responded again immediately, so that the aim of high-speed switching can be fulfilled.
In specific implementation, the circuit breaker (1) is provided with a tripping coil (7), and the control end of the tripping coil (7) is connected to a tripping wiring terminal of the module control board (6). The tripping coil is a coil winding, and a movable iron core is arranged in the middle of the tripping coil; when the rated voltage is applied to both ends of the trip coil, current flows through the winding to generate a magnetic field, attract the iron core and then push the mechanism to trip. The tripping coil of the embodiment is used for the lower port fault separation circuit breaker and is controlled to trip by the module control board (6).
In specific implementation, the silicon controlled rectifier and the diode are connected in anti-parallel to form a switching switch (3), wherein the anode of the diode is connected with the wire outlet side of the breaker (1), the cathode of the diode is connected with the reactor (4) in series, and the trigger end of the silicon controlled rectifier is connected to the trigger terminal of the module control board (6). The thyristor is a high-power electrical component, also called a thyristor.
In specific implementation, a radiator is further arranged on the switching switch (3), a temperature sensor is mounted on the radiator, and the temperature sensor is connected to a radiator temperature wiring terminal of the module control board (6). The temperature measuring sensor is used for detecting the temperature of the fling-cut switch in real time and transmitting the temperature to the module control panel (6) so as to realize the temperature monitoring of the fling-cut switch.
In the specific implementation, the reactor (4) is composed of three windings, each winding is provided with an independent wire inlet end and an independent wire outlet end, and each winding is provided with a temperature measuring sensor which is respectively connected to a reactance temperature wiring terminal of the module control board (6). The reactor and the capacitor form a partial harmonic loop, the specific harmonic current is absorbed or restrained, the closing charging current and the fault current of the low-voltage capacitor high-speed switching compensation module can be limited, a temperature sensor on the reactor (4) is used for monitoring the temperature of the reactor in real time, and the phenomenon that the reactor is damaged due to overhigh temperature to cause failure of the low-voltage capacitor high-speed switching compensation module is avoided.
In the specific implementation, the capacitor (5) is composed of three groups of independent single-phase capacitors, each group of capacitors is provided with a wire inlet end and a wire outlet end, each group of capacitors is provided with a temperature measuring sensor (8), and the temperature measuring sensors (8) are respectively connected to capacitance temperature wiring terminals of the module control board (6). The capacitor is an element generating capacitive reactive compensation current, and the temperature sensor (8) on the capacitor is used for monitoring the temperature of the capacitor in real time, so that the phenomenon that the capacitor is damaged due to overhigh temperature and the low-voltage capacitor high-speed switching compensation module fails is avoided.
In another specific embodiment, the low-voltage capacitor high-speed switching compensation module further comprises three current transformers (2), wherein the primary sides of the three current transformers (2) are respectively connected in series in three corner inner loops of a triangular connection method, and the secondary sides of the three current transformers are respectively connected with three current input ends of a module control board. The current transformer is an instrument for measuring by converting a large primary side current into a small secondary side current according to the electromagnetic induction principle. The current transformer is composed of a closed iron core and a winding. The current transformer is strung in the line of the current to be measured.
Wherein the digital phase locking unit includes:
the three AD conversion units are used for respectively converting the three-phase voltage analog signals of the power grid into digital signals;
the first adder and the second adder are used for respectively subtracting the A-phase voltage digital signal and the C-phase voltage digital signal from the B-phase voltage digital signal;
the first proportional regulator is connected with the output end of the first adder;
the second proportional regulator is connected with the output end of the second adder;
one input end of the first multiplier is connected with the first proportional regulator, the other input end of the first multiplier is connected with the output end of the first sine operator, and the input end of the first sine operator is connected with the output end of the integrator with the reset end;
a second multiplier, one input end of which is connected with the second proportional regulator, the other input end of which is connected with the output end of the second sinusoidal arithmetic unit, the input end of the second sinusoidal arithmetic unit is connected with the output end of a fourth adder, and two input ends of the fourth adder are respectively connected with the output end of the integrator at the reset end and a first constant (such as 120);
a third adder for adding the output results of the first multiplier and the second multiplier;
the low-pass filter is used for filtering harmonic signals, and the input end of the low-pass filter is connected with the output end of the third adder;
the input end of the PI regulator is connected with the output end of the low-pass filter, one output end of the PI regulator is connected with the input end of the second absolute value arithmetic unit, the output end of the second absolute value arithmetic unit is an angular frequency signal, and the other output end of the PI regulator is a phase sequence signal;
the input end of the third proportional regulator is connected with the output end of the PI regulator;
one input end of the integrator with the reset end is connected with the output end of the third proportional regulator, the other reset input end of the integrator with the reset end is connected with the output end of the comparator, and the output end of the integrator with the reset end is a phase signal;
and the positive input end of the comparator is connected with the output end of the first absolute value arithmetic unit, the input end of the first absolute value arithmetic unit is connected with the output end of the integrator with the reset end, and the negative input end of the comparator is connected with a second constant (such as 360).
In a specific implementation, as shown in fig. 2, the digital phase locking unit is composed of an AD conversion unit i (11), an AD conversion unit ii (12), an AD conversion unit iii (13), an adder i (14), an adder ii (15), an adder iii (20), an adder iv (29), a proportional regulator i (16), a proportional regulator ii (17), a proportional regulator iii (23), a multiplier i (18), a multiplier ii (19), a low-pass filter (21), a PI regulator (22), a sine calculator i (25), a sine calculator ii (28), an integrator (24) with a reset end, a comparator (27), an absolute value calculator i (26), and an absolute value calculator ii (30); the input end of the AD conversion unit I (11) is connected with a voltage Ua, and the output end of the AD conversion unit I is connected with a + input end of an adder I (14); the input end of the AD conversion unit II (12) is connected with the voltage Ub, the output ends are two, one output end is connected with the < - > input end of the adder I (14), and the other output end is connected with the < - > input end of the adder II (15); the input end of the AD conversion unit III (13) is connected with the voltage Uc, and the output end of the AD conversion unit III is connected with the + input end of the adder II (15); the input end of the proportional regulator I (16) is connected with the output end of the adder I (14), and the output end of the proportional regulator I is connected with one input end of the multiplier I (18); the input end of the proportional regulator II (17) is connected with the output end of the adder II (15), and the output end of the proportional regulator II is connected with one input end of the multiplier II (19); one input end of the adder III (20) is connected with the output end of the multiplier I (18), the other input end of the adder III is connected with the output end of the multiplier II (19), and the output end of the adder III is connected with the input end of the low-pass filter (21); the input end of the PI regulator (22) is connected with the output end of the low-pass filter (21), the output ends of the PI regulator are three, one output end of the PI regulator is connected with the input end of the proportional regulator III (23), one output end of the PI regulator is connected with the input end of the absolute value arithmetic unit II (30), and the other output end of the PI regulator is a phase sequence output signal Ps; the signal input end of an integrator (24) with a reset end is connected with the input contact end of a proportional regulator III (23), the reset input end of the integrator is connected with the output end of a comparator (27), and the four output ends of the integrator are respectively connected with the input end of a sine arithmetic unit I (25), the input end of a plus sign of an adder IV (29), the input end of an absolute value arithmetic unit (26) and a phase output signal alpha; the input end of the comparator (27) '+' is connected with the output end of the absolute value arithmetic unit (26), and the input end of the comparator '-' is connected with the second constant; the other "+" input end of the adder IV (29) is connected with the first constant, and the output end of the adder IV is connected with the sine operator II (28); the output end of the sine operator I (25) is connected with the other input end of the multiplier I (18), and the output end of the sine operator II (28) is connected with the other input end of the multiplier II (19); the output end of the absolute value arithmetic unit II (30) is an angular frequency signal omega; wherein the value of the proportional regulator III (23) is constant (e.g. 180/pi).
According to the embodiment, the digital phase-locking unit is realized through the hardware structure, so that the software phase-locking program is prevented from running away or being invalid, and further the reliable phase locking of the three-phase voltage of the power grid is realized.
In specific implementation, the inrush current-free switching logic unit is used for judging the phase of inrush current-free switching, the input end of the inrush current-free switching logic unit is connected with a power grid phase signal and a phase sequence signal output by the digital phase-locking unit, an inrush current-free input phase point is switched according to the power grid phase sequence signal, and when the actual phase is consistent with the inrush current-free input phase point, a trigger signal of a corresponding thyristor is output to input the capacitor.
As shown in fig. 3, the working flow of the inrush current-free switching logic unit is as follows: after receiving the input command, judging a phase sequence output signal Ps, and switching the corresponding silicon controlled rectifier according to the following phase output signal alpha if the phase sequence output signal Ps is greater than 0: judging alpha, setting the thyristor trigger signal Drab between AB to be 1 when alpha is 150, and putting the thyristor between AB; judging alpha, setting a thyristor trigger signal Drbc between BC to be 1 when the alpha is 270, and inputting the thyristor between BC; and judging alpha, setting the thyristor trigger signal Drca between CAs to be 1 when the alpha is 30, and inputting the thyristor between the CAs. Judging the phase sequence signal Ps, and switching the corresponding silicon controlled rectifier according to the following phase output signal alpha if the phase sequence output signal Ps is less than or equal to 0: judging alpha, setting the thyristor trigger signal Drab between AB to be 1 when the alpha is-210, and putting the thyristor between AB; judging alpha, setting a thyristor trigger signal Drbc between BC to be 1 when the alpha is-90, and inputting the thyristor between BC; and judging alpha, setting the thyristor trigger signal Drca between CAs to be 1 when the alpha is-330, and inputting the thyristor between the CAs.
In a specific embodiment, the module control board (6) is further provided with a capacitance attenuation protection unit, the capacitance attenuation protection unit is used for detecting and protecting the attenuation rate of the capacitance value of the capacitor, the input end of the capacitance attenuation protection unit is connected with the power grid voltage, the compensation current and the voltage frequency output by the digital phase locking unit, the capacitance value of the capacitor is calculated by combining the actual reactance rate and the capacitance value of the capacitor nameplate in an online simulation mode, the attenuation rate of the capacitor is calculated, and when the capacitance attenuation rate exceeds a set value, an alarm shutdown signal is output.
In specific implementation, the module control board (6) is further provided with a harmonic protection unit, the harmonic protection unit is used for monitoring and protecting harmonic content of voltage and compensation current, the input end of the harmonic protection unit is connected with power grid voltage and compensation current, a fundamental wave value and a harmonic value are calculated according to the sampled power grid voltage and compensation current, the harmonic content of the power grid voltage and the harmonic content of the compensation current are respectively calculated, and an alarm shutdown signal is output when the harmonic content exceeds respective set protection values.
In a specific embodiment, the module control panel (6) is further provided with a silicon controlled breakdown protection unit, the silicon controlled breakdown protection unit is used for judging and protecting the breakdown state of the silicon controlled, the input end of the silicon controlled breakdown protection unit is connected with a trigger instruction and a compensation current, the state of the silicon controlled is obtained according to the trigger instruction and the compensation current, and a tripping signal is output to a switching-off coil of the circuit breaker after breakdown is found.
The capacitance attenuation protection unit, the harmonic protection unit and the silicon controlled breakdown protection unit solve the problem of monitoring and protection at the initial fault stage of the capacitor compensation branch circuit, and can avoid the expansion of accidents.
Specifically, the module control board (6) is further provided with a full-duplex communication unit, the full-duplex communication unit is provided with a full-duplex communication interface, and receives a high-speed switching communication instruction of an external controller in a broadcast instruction interception mode and sends state information of the module control board in the full-duplex mode.
In a specific embodiment, the module control board (6) is further provided with a temperature protection unit which is used for sampling the temperature of the capacitor (5), the temperature of the reactor, the temperature of the radiator on the switching switch and the ambient temperature, the temperature protection unit is used for calculating the temperature rise of the radiator on the capacitor (5), the reactor (4) and the switching switch (3), and when the temperature or the temperature rise of the radiator on the capacitor (5), the reactor (4) and the switching switch (3) exceeds a set protection value, an alarm shutdown signal is output.
The control method for the low-voltage capacitor high-speed switching compensation module in the embodiment comprises the following steps:
when the circuit breaker (1) is closed, the module control board (6) is used for sampling the three-phase voltage of the power grid, and the phase sequence and the phase of the power grid voltage are obtained after phase locking is carried out by the digital phase locking unit;
after the compensation module receives an external input command, the inrush current-free switching logic unit judges the phase according to the phase sequence of the power grid voltage and finds the moment of the positive peak point of the three-phase line voltage of the power grid, and silicon controlled instructions in the trigger switching switch (3) are respectively sent out at the positive peak point of the three-phase line voltage of the power grid to input the silicon controlled instructions into the capacitor (5);
after the compensation module receives an external cutting command, the phase is judged according to the current power grid voltage phase sequence, the moment of the positive zero crossing point of the power grid three-phase line voltage (namely that the line voltage is directly opposite to the current of a diode in a corresponding fling-cut switch from negative change and is taken as the peak value) is found, the silicon controlled rectifier command in the fling-cut switch (3) is respectively sent out to stop triggering, the silicon controlled rectifier is naturally cut off at the zero current position, then the diode is cut off after being conducted for half power frequency period, the capacitor cutting is completed, at the moment, three groups of capacitors (5) are fully charged through the diodes respectively, and the compensation module can immediately respond the external cutting command again to enable the capacitors (5) to be cut again so as to achieve the purpose of high-speed cutting.
When the module control panel (6) is composed of a digital phase-locking unit, a no-inrush current switching logic unit, a capacitance attenuation protection unit, a harmonic protection unit, a silicon controlled breakdown protection unit, a full-duplex communication unit and a temperature protection unit, the control method of the corresponding low-voltage capacitor high-speed switching compensation module is as follows:
when the module control board (6) is connected with a power supply and the circuit breaker (1) is closed, three groups of capacitors in the capacitors (5) are charged to a positive peak point of the voltage of the power grid line through diodes in the switching switch (3), the module control board (6) samples the three-phase voltage of the power grid, and the phase sequence and the phase of the voltage of the power grid are obtained after the phase locking of the digital phase locking unit; after the compensation module receives an external input command, the inrush current-free switching logic unit judges the phase according to the phase sequence of the power grid voltage and finds the moment of the positive peak point of the three-phase line voltage of the power grid, and silicon controlled instructions in the trigger switching switch (3) are respectively sent out at the positive peak point of the three-phase line voltage of the power grid to input the silicon controlled instructions into the capacitor (5);
after the compensation module receives an external cutting command, the phase is judged according to the current power grid voltage phase sequence, the moment of the positive zero crossing point of the power grid three-phase line voltage (namely that the line voltage is directly opposite to the current of a diode in a corresponding fling-cut switch from negative change and is taken as the peak value) is found, the silicon controlled rectifier command in the fling-cut switch (3) is respectively sent out to stop triggering, the silicon controlled rectifier is naturally cut off at the zero current position, then the diode is cut off after being conducted for half power frequency period, the capacitor cutting is completed, at the moment, three groups of capacitors (5) are fully charged through the diodes respectively, and the compensation module can immediately respond the external cutting command again to enable the capacitors (5) to be cut again so as to achieve the purpose of high-speed cutting.
The capacitance value attenuation protection unit analyzes fundamental voltage and fundamental compensation current according to sampled three-phase voltages Ua, Ub and Uc and compensation currents Iab, Ibc and Ica in a three-phase-angle inner loop through a Fourier algorithm, calculates capacitance value attenuation rate according to the fundamental voltage, the fundamental compensation current and voltage frequency output by the phase locking unit and by combining actual reactance rate and capacitance nameplate capacitance value parameters, and outputs an alarm shutdown signal when the capacitance value attenuation rate exceeds a set protection value;
the harmonic protection unit analyzes fundamental voltage, fundamental compensation current, harmonic voltage and harmonic compensation current through a Fourier algorithm according to the sampled three-phase voltages Ua, Ub and Uc and the compensation currents Iab, Ibc and Ica in the three-phase-angle inner loop, calculates the voltage harmonic content and the compensation current harmonic content, and outputs an alarm shutdown signal when the voltage harmonic content and the compensation current harmonic content exceed respective set protection values;
the module control board (6) samples the temperature of the capacitor (5), the temperature of the reactor (4), the temperature of the switching switch (3) radiator and the ambient temperature, respectively calculates the temperature rise of the capacitor (5), the reactor (4) and the switching switch (3) radiator, and outputs an alarm shutdown signal once the temperature or the temperature rise of the capacitor (5), the reactor (4) and the switching switch (3) radiator exceeds a set protection value;
the thyristor breakdown protection unit detects the compensation currents Iab, Ibc and Ica in real time, when no thyristor trigger signal exists, if the compensation current is detected, the thyristor breakdown or critical breakdown phenomenon is indicated, and the thyristor breakdown protection unit can send a module trip instruction to the trip coil (7) to break the circuit breaker (1) of the module to be separated from a main loop;
the full-duplex communication unit of the module control board (6) is provided with a full-duplex communication interface, receives a high-speed switching communication instruction of an external controller in a broadcast instruction interception mode and sends the state information of the module in a full-duplex mode.
The control method based on the low-voltage capacitor high-speed switching compensation module comprises the following steps:
the method comprises the steps that the three-phase voltage of a digital phase-locked power grid obtains the phase sequence and the phase of the power grid voltage;
when the compensation module receives an external input command, the phase is judged according to the phase sequence of the power grid voltage, the moment of the positive peak point of the three-phase line voltage of the power grid is found, and the silicon controlled instructions for triggering the switching switch are sent out at the positive peak point of the three-phase line voltage of the power grid respectively to input the silicon controlled instructions into the capacitor;
after the compensation module receives an external cutting command, the phase is judged according to the current power grid voltage phase sequence, the moment of the positive zero crossing point of the power grid three-phase line voltage (namely the line voltage is directly opposite to the current of a diode in a corresponding fling-cut switch from negative change and is taken as the peak value) is found, the silicon controlled rectifier instruction for stopping triggering the fling-cut switch is respectively sent, the silicon controlled rectifier is naturally cut off at the zero current position, then the diode is switched on and is cut off after half power frequency period, the capacitor cutting is completed, at the moment, three groups of capacitors are fully charged through the diodes respectively, and the compensation module can immediately respond the external cutting command to enable the capacitors to be cut again so as to achieve the purpose of high-speed switching.
The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (10)
1. A high-speed switching compensation module of a low-voltage capacitor is characterized by comprising a circuit breaker, a switching switch, a reactor, a capacitor and a module control board, wherein the switching switch, the reactor and the capacitor are connected in series to form an inner triangle and are connected to the outlet side of the circuit breaker in parallel, and the inlet side of the circuit breaker is connected with a power supply;
the module control panel is provided with a digital phase locking unit and a no-inrush current switching logic unit; the digital phase-locking unit is used for locking the phase of the three-phase voltage of the power grid; the inrush current-free switching logic unit is used for finding the peak point moment of the three-phase voltage of the power grid after phase locking, and triggering a switching switch at the peak point of the three-phase voltage of the power grid and putting the switching switch into a capacitor after receiving an external input command;
the switching-on/off part is composed of a silicon controlled rectifier and a diode which are connected in anti-parallel; when the silicon controlled rectifier in the fling-cut switch is turned off, the capacitor is charged through the diode, and the capacitor is charged to the voltage when the line voltage is peak when the diode is turned off, namely the fling-cut switch is turned off, so that the aim of high-speed fling-cut can be achieved by waiting for re-responding to fling-cut instructions.
2. The low-voltage capacitor high-speed switching compensation module according to claim 1, wherein an input terminal of the inrush current-free switching logic unit receives the phase signal and the phase sequence signal of the power grid after digital phase locking, the inrush current-free switching logic unit is configured to switch an inrush current-free input phase point according to the phase sequence signal of the power grid, and when an actual phase is consistent with the inrush current-free input phase point, a trigger signal input capacitor of a thyristor in a corresponding switching switch is output.
3. The low-voltage capacitor high-speed switching compensation module according to claim 1, wherein a capacitance attenuation protection unit is further arranged on the module control board, the input end of the capacitance attenuation protection unit is connected with the voltage of the power grid, the compensation current and the voltage frequency after digital phase locking, the capacitance value of the capacitor is calculated by combining the actual reactance rate and the capacitance value of the capacitor nameplate in an online simulation mode, the attenuation rate of the capacitor is calculated, and an alarm shutdown signal is output when the attenuation rate of the capacitor exceeds a set value.
4. The low-voltage capacitor high-speed switching compensation module according to claim 1, wherein a harmonic protection unit is further disposed on the module control board, and an input end of the harmonic protection unit is connected to the grid voltage and the compensation current, and calculates a fundamental wave value and a harmonic wave value according to the sampled grid voltage and compensation current, and respectively calculates harmonic wave contents of the grid voltage and the compensation current, and outputs an alarm shutdown signal when the harmonic wave contents exceed respective set protection values.
5. The low-voltage capacitor high-speed switching compensation module according to claim 1, wherein a thyristor breakdown protection unit is further arranged on the module control board, an input end of the thyristor breakdown protection unit receives a trigger instruction and a compensation current, the state of a thyristor is obtained according to the trigger instruction and the compensation current, and a tripping signal is output to a switching-off coil of the circuit breaker after breakdown is found;
or the module control panel is also provided with a full-duplex communication unit which is provided with a full-duplex communication interface, receives a high-speed switching communication instruction of an external controller in a broadcast instruction interception mode and sends the state information of the module control panel in a full-duplex mode.
6. The low-voltage capacitor high-speed switching compensation module according to claim 1, wherein a temperature protection unit is further arranged on the module control board and used for sampling the temperature of the capacitor, the temperature of the reactor, the temperature of the radiator on the switching switch and the ambient temperature, the temperature protection unit is used for calculating the temperature or temperature rise of the radiator on the capacitor, the reactor and the switching switch, and when the temperature or temperature rise of the radiator on the capacitor, the reactor and the switching switch exceeds a set protection value, an alarm shutdown signal is output;
or the low-voltage capacitor high-speed switching compensation module also comprises a current transformer, wherein the primary side of the current transformer is respectively connected in series in three corner inner loops of a triangular connection method, and the secondary side of the current transformer is respectively connected with three current input ends of the module control board.
7. The low-voltage capacitor high-speed switching compensation module according to claim 1, wherein the circuit breaker is provided with a trip coil, and a control end of the trip coil is connected to a trip connection terminal of a module control board.
8. The low-voltage capacitor high-speed switching compensation module according to claim 1, wherein a radiator is further arranged on the switching switch, a temperature sensor is mounted on the radiator, and the temperature sensor is connected to a radiator temperature terminal of a module control board;
or the reactor is composed of three windings, each winding is provided with an independent wire inlet end and an independent wire outlet end, and each winding is provided with a temperature sensor which is respectively connected to a reactance temperature wiring terminal of the module control board;
or the capacitor is composed of three groups of independent single-phase capacitors, each group of capacitors is provided with a wire inlet end and a wire outlet end, each group of capacitors is provided with a temperature measuring sensor, and the temperature measuring sensors are respectively connected to the capacitance temperature wiring terminals of the module control board.
9. The low-voltage capacitor high-speed switching compensation module according to claim 1, wherein the digital phase-locking unit comprises:
the three AD conversion units are used for respectively converting the three-phase voltage analog signals of the power grid into digital signals;
the first adder and the second adder are used for respectively subtracting the A-phase voltage digital signal and the C-phase voltage digital signal from the B-phase voltage digital signal;
the first proportional regulator is connected with the output end of the first adder;
the second proportional regulator is connected with the output end of the second adder;
one input end of the first multiplier is connected with the first proportional regulator, the other input end of the first multiplier is connected with the output end of the first sine operator, and the input end of the first sine operator is connected with the output end of the integrator with the reset end;
one input end of the second multiplier is connected with the second proportional regulator, the other input end of the second multiplier is connected with the output end of the second sine arithmetic unit, the input end of the second sine arithmetic unit is connected with the output end of a fourth adder, and two input ends of the fourth adder are respectively connected with the output end of the integrator with the reset end and a first constant;
a third adder for adding the output results of the first multiplier and the second multiplier;
the low-pass filter is used for filtering harmonic signals, and the input end of the low-pass filter is connected with the output end of the third adder;
the input end of the PI regulator is connected with the output end of the low-pass filter, the output end of the PI regulator is connected with the input end of the second absolute value arithmetic unit, the output end of the second absolute value arithmetic unit is an angular frequency signal, and the other output end of the PI regulator is a phase sequence signal;
the input end of the third proportional regulator is connected with the output end of the PI regulator;
one input end of the integrator with the reset end is connected with the output end of the third proportional regulator, the other reset input end of the integrator with the reset end is connected with the output end of the comparator, and the output end of the integrator with the reset end is a phase signal;
and the positive input end of the comparator is connected with the output end of the first absolute value operator, the input end of the first absolute value operator is connected with the output end of the integrator with the reset end, and the negative input end of the comparator is connected with the second constant.
10. A control method of a low-voltage capacitor high-speed switching compensation module according to any one of claims 1 to 9, comprising:
the method comprises the steps that the three-phase voltage of a digital phase-locked power grid obtains the phase sequence and the phase of the power grid voltage;
when the compensation module receives an external input command, the phase is judged according to the phase sequence of the power grid voltage, the moment of the positive peak point of the three-phase line voltage of the power grid is found, and the silicon controlled instructions for triggering the switching switch are sent out at the positive peak point of the three-phase line voltage of the power grid respectively to input the silicon controlled instructions into the capacitor;
after the compensation module receives an external cutting command, the phase is judged according to the current phase sequence of the power grid voltage, the forward zero crossing time of the three-phase line voltage of the power grid is found, the silicon controlled rectifier commands of the cut-in and cut-off switch are respectively sent out to stop triggering, the silicon controlled rectifiers are naturally turned off at the zero current position, then the diodes are turned on and cut off after a half power frequency period, the capacitor cutting is completed, at the moment, the three groups of capacitors are fully charged through the diodes, and the compensation module immediately responds to the external input command again to enable the capacitors to be put in again to achieve the purpose of high-speed cutting.
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