CN111725816A - FC-TCR type SVC reactive power control system and method for weak transmission end system - Google Patents
FC-TCR type SVC reactive power control system and method for weak transmission end system Download PDFInfo
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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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- 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
- H02J3/36—Arrangements for transfer of electric power between ac networks via a high-tension dc link
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- 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
- Y02E40/10—Flexible AC transmission systems [FACTS]
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- 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
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Abstract
The invention provides a control system and a control method for inhibiting FC-TCR type SVC reactive power reverse regulation of a weak transmitting end system under a direct current commutation failure fault, wherein the system comprises: the device comprises a voltage and current measuring module, a signal filtering calculation module, a communication module, a man-machine interaction module, a microprocessor control module, a thyristor triggering module, an opening and closing control module and a secondary system isolation module. By acquiring FC-TCR type SVC grid-connected bus voltage data, dividing the bus voltage state of a transmission end alternating current system during a commutation failure fault period and after the fault is ended into: and (3) voltage reduction stage: when the voltage of the FC-TCR type SVC access point is detected to be lower than a certain value, the initial condition of controlling starting is met, and the FC-TCR type SVC control method is kept unchanged; and (3) voltage recovery stage: when the voltage of the FC-TCR type SVC access point is detected to be recovered to a certain value or more and the change rate of the effective voltage value is positive, the fixed capacitor is disconnected; and (3) voltage stabilization stage: after the access point voltage recovers to be stable, the fixed capacitors are put into operation in stages.
Description
Technical Field
The invention relates to a FC-TCR type SVC reactive power back control system and method for a weak transmitting end system, which are used for inhibiting direct current commutation failure faults and belong to the technical field of power automation.
Background
The high-voltage direct-current transmission technology is widely applied to 'West and east power transmission' projects in China, and the technology makes the development and the consumption of clean energy in 'three northeast' areas in China possible. Research finds that the voltage of a power grid at a transmitting end is changed violently due to reactive fluctuation caused by phase commutation failure because a direct current transmitting system containing high-proportion new energy is relatively weak: when the commutation fails, a short circuit at a direct current side is caused, the direct current is rapidly increased, and the reactive power consumed by a rectifier side converter in the period is instantly increased, so that the voltage of an alternating current bus at the rectifier side is reduced; the rectifier station is generally provided with a current control link, and the function of the current control link is to rapidly reduce direct current to zero, so that redundant reactive power generated by a filter arranged on the converter station side is completely injected into an alternating current power grid on the rectifier side, and therefore transient overvoltage occurs, and even disordered grid disconnection of new energy can be caused under severe conditions, and stable operation of the power grid is seriously threatened.
The dynamic reactive compensation is crucial to the safe and stable operation of a power grid, a large number of Static Var Compensators (SVCs) are configured in new energy stations operated by a direct current transmission end system, but researches show that the FC-TCR type SVCs and other dynamic reactive compensation configured in the new energy stations have a reverse regulation characteristic and generate a hysteresis reactive power at low voltage; when the system is in overvoltage, the phase-entering reactive power cannot immediately follow up, the phase-lagging reactive power is still sent out, and the overvoltage is further raised. The reactive compensation characteristic of the FC-TCR type SVC is not beneficial to the safe and stable operation of the system, so that it is necessary to make corresponding inhibition measures aiming at the reactive compensation characteristic of the FC-TCR type SVC.
Disclosure of Invention
Aiming at the problems, the invention provides an FC-TCR type SVC reactive power regulation control system and method for inhibiting a weak transmitting end system under a direct current commutation failure fault.
According to one aspect of the invention, the invention provides a weak sending end system FC-TCR type SVC reactive power regulation system, which is applied to the situation of restraining direct current commutation failure fault, and is characterized in that the system comprises: the device comprises a voltage and current measuring module (1), an isolation module I (2), a signal filtering calculation module (3), a communication module (4), a man-machine interaction module (5), a microprocessor control module (6), an isolation module II (7), an isolation module III (8), an opening and closing control module (9), a thyristor trigger module (10), a thyristor (11) and a switch (12);
the device comprises a voltage and current measuring module (1), an isolation module I (2), a signal filtering calculation module (3), a microprocessor control module (6), an isolation module III (8), an opening and closing control module (9) and a switch (12) which are sequentially connected; the microprocessor control module (6), the isolation module II (7), the thyristor trigger module (10) and the thyristor (11) are connected in sequence; the signal filtering calculation module (3) is respectively connected with the communication module (4) and the human-computer interaction module (5); the human-computer interaction module (5) is connected with the microprocessor control module (6);
the voltage and current measuring module (1) is used for acquiring voltage and current data of an FC-TCR type SVC grid-connected point from a power grid and transmitting the voltage and current data to the isolating module I (2);
the isolation module I (2) realizes the isolation of a secondary system, converts a strong current signal into a weak current signal and transmits the weak current signal to the signal filtering calculation module (3);
the signal filtering calculation module (3) is used for processing voltage and current data, has the functions of filtering and effective value calculation, and transmits the obtained signals to the communication module (4), the human-computer interaction module (5) and the microprocessor control module (6);
the communication module (4) is used for realizing remote transmission of the obtained signals;
the human-computer interaction module (5) comprises a keyboard, a display and a conversion interface, and is used for setting parameters, displaying data and states of the system in real time and realizing serial communication between the system and an upper computer;
the microprocessor control module (6) completes calculation of the conduction angle of the thyristor and switching control of the capacitor according to information input by the signal filtering calculation module 3 and the human-computer interaction module (5), the signal of the conduction angle of the thyristor is output to the isolation module II (7), and the switching control signal of the capacitor is output to the isolation module III (8), so that control over the SVC primary system is realized;
the input end of the isolation module II (7) is connected with the thyristor control output end of the microprocessor control module (6), weak current signals are converted into strong current signals, and the strong current signals are transmitted to the thyristor trigger module (10), so that the isolation of a secondary system is realized;
the input end of the isolation module III (8) is connected with the capacitor switching control signal output end of the microprocessor control module (6), weak current signals are converted into strong current signals, and the strong current signals are transmitted to the switching control module (9) to realize primary and secondary system isolation;
the input end of the switching control module (9) is connected with the output end of the isolation module III (8), and the switch of the fixed capacitor is controlled according to an input signal;
the input end of the thyristor trigger module (10) is connected with the second isolation module (7), and the conduction angle of the thyristor is controlled according to the input signal.
Preferably, the isolation module I (2) consists of a Hall voltage transformer and a photoelectric isolation circuit for measuring SVC terminal voltage, wherein the Hall voltage sensor is of HVS5-25A type and is provided with a primary side current limiting resistor R1Characterized as follows:
R1＝U1/IP-Rin
in the formula R1Is a primary side current limiting resistor, U1To maximum measurement voltage, IPFor rating input current, R, of mutual inductorinIs the internal resistance of the primary side of the mutual inductor;
the photoelectric isolation circuit adopts a double-path photoelectric coupling chip with the model of TLP521-2, two paths of completely symmetrical and independent optocouplers with completely consistent physical characteristics are packaged in the photoelectric isolation circuit, and each optocoupler comprises a light emitting diode and a phototriode;
when a forward voltage is applied to two ends of a light emitting diode in the optocoupler, the light emitting diode is conducted and emits light, a photosensitive surface of the phototriode is irradiated by the light, and if the forward voltage is applied between an emitter and a collector of the phototriode, the triode has a collector current output.
Further preferably, the rated input current I of the hall voltage transformerPIs 5mA, the maximum voltage U is measured1Is 5V, the primary side current limiting resistor R1The output voltage U of the Hall voltage transformer is selected to be 360 omega0And the measured maximum voltage U1Are considered to be equal.
Preferably, the switch (12) is connected to a fixed capacitor switch, the fixed capacitor switch includes two level comparators, a sample holder 1, a sample controller, a sample holder 2, two monostable flip-flops, a slope determination module, and an and gate, one of the two level comparators is connected to one of the two monostable flip-flops and then connected to the and gate, and the and gate outputs a signal to the other monostable flip-flop; the other of the two level comparators is directly connected to the AND gate;
the input signal of the fixed capacitor switch comes from a human-computer interaction module (5) and a signal processing module, and the signal processing module inputs the effective value signal of the output voltage to the fixed capacitor switch.
More preferably, the slope determining module is composed of two level comparators and an and gate, and the input signals of the slope determining module are from the sample holder 1, the sample holder 2 and the signal processing module, the signal input by the signal processing module to the fixed capacitor switch is an effective value signal of the output voltage of the signal processing module, and the slope determining module outputs the level signal to the and gate of the fixed capacitor switch.
More preferably, the level comparator is composed of an operational amplifier and a schmitt trigger, the schmitt trigger adopts a 555 timing chip, the output of the operational amplifier is connected to pins 2 and 6 of the 555 timing chip, and a pull-up resistor R is connected to a pin 7 of the 555 timing chip; the monostable trigger adopts a 555 timing chip, and pins 6 and 7 of the 555 timing chip are connected with pull-up resistors R 16 th and 7 th pinsAnd is also connected with a decoupling capacitor C1The 5 th pin is connected with a decoupling capacitor C2。
Further preferably, the sample holder is constructed by cascading 3 LF398 chips, wherein the output terminal pin 5 of the 1 st LF398 chip is connected to the input terminal pin 3 of the 2 nd LF398 chip, and the output terminal pin 5 of the 2 nd LF398 chip is connected to the input terminal pin 3 of the 3 rd LF398 chip; and the control end 8 pin of the 1 st LF398 chip and the control end 8 pin of the 3 rd LF398 chip are both accessed into an external sampling control signal, and meanwhile, the sampling control signal is accessed into the control end 8 pin of the 2 nd LF398 chip after passing through the NOT gate.
Preferably, the sampling control signal is generated by a 3140 arithmetic chip and is a square wave signal with a certain period.
Preferably, the isolation module three (8) adopts a two-way photoelectric coupling chip with the model of TLP521-2, and can convert a weak electric signal of a control system into a strong electric signal; the external switching signal passes through a resistor R3A 1 st pin connected to the TLP521-2 to drive the light emitting diode in the TLP521-2 to emit light, a collector and an emitter of a phototransistor in the TLP521-2 after receiving light are turned on, a 7 th pin of the TLP521-2 outputs a level lower than a power supply voltage VCC-2, and a resistor R is connected in series between the 7 th pin of the TLP521-2 and ground2。
According to another aspect of the invention, a control method using the control system is provided, and the method is applied to the situation of suppressing the direct current commutation failure fault, and divides the bus voltage state of the sending-end alternating current system during the commutation failure fault and after the fault is ended into the following steps by acquiring the voltage data of the FC-TCR type SVC grid-connected bus: a voltage reduction stage, a voltage recovery stage and a voltage stabilization stage;
in the voltage reduction stage, when the voltage of the FC-TCR type SVC access point is detected to be lower than a certain value, the initial condition of starting control of a control system is met, and the SVC control method is kept unchanged;
in the voltage recovery stage, when the voltage recovery of the FC-TCR type SVC access point is detected to be more than a certain value and the change rate of the effective voltage value is positive, the fixed capacitor is disconnected;
in the voltage stabilization stage, after the voltage of the access point recovers to be stable, the fixed capacitors are put into operation in a grading mode.
Further, the control method includes the steps of:
the first step is as follows: collecting an FC-TCR type SVC grid-connected point voltage instantaneous value, and solving a real-time voltage effective value;
the second step is that: judging whether the effective value of the voltage is lower than the minimum voltage set value or not;
the third step: when the effective voltage value is higher than the minimum voltage set value, returning to the step two, when the effective voltage value is lower than the minimum voltage set value, recording the time T1, and going to the fourth step;
the fourth step: inputting a real-time voltage effective value Urms, values U1 and U2 of a sampling holder and the current time T2;
the fifth step: ending logic judgment when T2-T1< Tmax is not satisfied, and turning to the sixth step when T2-T1< Tmax is satisfied;
and a sixth step: when any one of the conditions of Urms > Umax and U1< U2< Urms is not satisfied, the step goes to a fourth step, and when two conditions of Urms > Umax and U1< U2< Urms are simultaneously satisfied, the step goes to a seventh step;
the seventh step: and (5) disconnecting the fixed capacitor switch, closing the fixed capacitor switch after delaying Tmin millisecond, and ending the switching control.
Advantageous effects of the invention
According to the voltage change rule of the weak transmission end power grid caused by commutation failure, the voltage state of the FC-TCR type SVC grid-connected point is divided into three stages, and logic judgment is carried out on each stage, so that the switching operation of the capacitor is controlled, the reactive reverse modulation phenomenon of the FC-TCR type SVC is effectively inhibited, and the risk of high-voltage network disconnection of new energy of a transmission end system is reduced.
Drawings
FIG. 1 is a block diagram of the control system components of the present invention;
FIG. 2 is a circuit diagram of an isolation module;
FIG. 3 is a flow chart of a fixed capacitor switch control method;
FIG. 4 is a schematic block diagram of fixed capacitor switch control;
FIG. 5 is a schematic diagram of a slope determination module;
FIG. 6 is a circuit diagram of a level comparator;
FIG. 7 is a circuit diagram of a monostable flip-flop;
FIG. 8 is a sample and hold circuit diagram;
FIG. 9 is a sample and hold control signal generation circuit diagram;
FIG. 10 is a circuit diagram of an isolation module II;
FIG. 11 is a three circuit diagram of an isolation module;
fig. 12 is a comparison graph of SVC grid-connected point voltage curves.
Reference numerals:
1-a voltage current measurement module;
2-isolation module one
3-signal filtering calculation module
4-communication module
5-human-computer interaction module
6-microprocessor control module
7-isolation module II
8-isolation module III
9-switching control module
10-thyristor trigger module
11-thyristor
12-switch
Detailed Description
The embodiments are described in detail below with reference to the accompanying drawings.
The invention provides an FC-TCR type SVC reactive power feedback control system for inhibiting a weak sending end system under a direct current commutation failure fault, as shown in figure 1, a voltage and current measurement module (1), an isolation module I (2), a signal filtering calculation module (3), a microprocessor control module (6), an isolation module III (8), an opening and closing control module (9) and a switch (12) are sequentially connected; the microprocessor control module (6), the isolation module II (7), the thyristor trigger module (10) and the thyristor (11) are connected in sequence; the signal filtering calculation module (3) is respectively connected with the communication module (4) and the human-computer interaction module (5); the man-machine interaction module (5) is connected with the microprocessor control module (6).
Fig. 2 is a circuit diagram of an isolation module, which is composed of a hall voltage transformer and a photoelectric isolation circuit, wherein the hall voltage sensor for measuring the SVC terminal voltage is of HVS5-25A type, and a primary side current limiting resistor is configured:
R1＝U1/IP-Rin
in the formula R1Is a primary side current limiting resistor, U1To maximum measurement voltage, IPFor rating input current, R, of mutual inductorinIs the primary internal resistance of the mutual inductor.
Because the Hall sensor requires the rated input current of the primary side to be about 5mA, the maximum voltage U is measured1The primary current limiting resistor R is selected as 5V1Comprises the following steps:
R1＝5V/5mA-650＝350Ω
taking R according to the actual resistance value1Selecting output voltage as U as 360 omegaoWhen the number of turns is 5V, the formula is shown as follows:
obtaining: rm＝200Ω
Therefore, the output voltage UoTo the measured voltage U1The actual relationship between the two is as follows:
the photoelectric isolation circuit adopts a double-path photoelectric coupling chip with the model of TLP521-2, and two paths of completely symmetrical and independent optical couplers with completely consistent physical characteristics are packaged inside the photoelectric isolation circuit. When a forward voltage is applied to two ends of the light-emitting diode, the diode is conducted and emits light, the photosensitive surface of the phototriode is irradiated by the light, and if the forward voltage is applied between the emitter and the collector of the phototriode, the phototriode outputs collector current.
Fig. 3 is a flow of a fixed capacitor switch control method, which specifically includes the following steps:
the first step is as follows: collecting an FC-TCR type SVC grid-connected point voltage instantaneous value, and solving a real-time voltage effective value;
the second step is that: judging whether the effective value of the voltage is lower than the minimum voltage set value or not;
the third step: when the effective value of the voltage is higher than the minimum voltage set value, returning to the step two, and when the effective value of the voltage is lower than the minimum voltage set value, recording the moment T1And go to the fourth step;
the fourth step: input real-time voltage effective value UrmsValue of sample and holder U1、U2And the current time T2;
the fifth step: when T is not satisfied2-T1<TmaxWhen T is satisfied, the logic judgment is ended2-T1<TmaxTurning to the sixth step;
and a sixth step: when U is not satisfiedrms>UmaxAnd U1<U2<UrmsIn any condition, go to step four, when Urms>UmaxAnd U1<U2<UrmsWhen the two conditions are simultaneously met, turning to the step seven;
the seventh step: by switching off the fixed capacitor switch, with a delay of TminAnd closing the fixed capacitor switch after the millisecond, and finishing the switching control.
Fig. 4 is a schematic diagram of switch control of a fixed capacitor, which is composed of a level comparator, a sample holder, a monostable trigger, a slope judgment module and the like, wherein input signals of the fixed capacitor come from a human-computer interaction module and a signal processing module.
Fig. 5 is a schematic diagram of a slope determination module, which is composed of a level comparator and an and gate, and input signals of the slope determination module come from a sample holder and a signal processing module.
FIG. 6 is a circuit diagram of a level comparator, which is composed of an operational amplifier and a Schmitt trigger, wherein the Schmitt trigger adopts a 555 timing chip, the output of the operational amplifier is connected to pins 2 and 6 of the 555 timing chip, and a pin 7 of the 555 timing chip is connected with a pull-up resistor.
FIG. 7 is a circuit diagram of a monostable flip-flop using a 555 timer chip, 555 timerPull-up resistor R connected to pins 6 and 7 of time chip1Pins 6 and 7 are also connected with a decoupling capacitor C1And pin 5 is connected to a decoupling capacitor C2.
Fig. 8 is a circuit diagram of a sample-and-hold device, in which 3 LF398 chips are cascaded, the pin 5 of the output terminal of the 1 st LF398 chip is connected to the pin 3 of the input terminal of the 2 nd LF398 chip, and the pin 5 of the output terminal of the 2 nd LF398 chip is connected to the pin 3 of the input terminal of the 3 rd LF398 chip. The control end 8 feet of the 1 st LF398 chip and the control end 8 feet of the 3 rd LF398 chip are both connected with external sampling control signals, and meanwhile, the sampling control signals are connected with the control end 8 feet of the 2 nd LF398 chip after passing through the NOT gate.
FIG. 9 is a circuit diagram of a sample and hold control signal generation circuit, using a 3140 chip, for R1＝R2Then the circuit can generate a square wave signal with a period of T, and the period calculation formula is:
T＝R1C+R2C
fig. 10 shows a photoelectric isolation circuit, which uses a double-path photoelectric coupling chip with model number TLP521-2, and two paths of completely symmetrical, independent and physically identical optocouplers are packaged inside the photoelectric isolation circuit. When a forward voltage is applied to two ends of the light-emitting diode, the diode is conducted and emits light, the photosensitive surface of the phototriode is irradiated by the light, and if the forward voltage is applied between the emitter and the collector of the phototriode, the phototriode outputs collector current.
Fig. 11 is a three-circuit diagram of an isolation module, which adopts a two-way photoelectric coupling chip with the model of TLP521-2 to convert weak electric signals of a control system into strong electric signals. The external switching signal passes through a resistor R3Is connected to the 1 st pin of the TLP521-2 to drive the light emitting diode to emit light, the base terminal of the phototransistor receives light and then the collector and the emitter are conducted, the 7 th pin of the TLP521-2 outputs a level slightly lower than the power supply voltage VCC-2, and meanwhile, in order to prevent overcurrent, a resistor R is connected in series between the 7 th pin of the TLP521-2 and the ground2。
Fig. 12 is a comparison graph of voltage curves of SVC grid-connected points, and based on a CIGRE dc transmission model, an FC-TCR type SVC is provided in a transmitting-end ac system, and a voltage waveform of a transmitting-end ac grid occurs when a phase commutation failure occurs on an inverting side. As can be seen from the figure, after the control method disclosed by the invention is adopted, the overvoltage of the FC-TCR type SVC grid-connected bus in the transient period is restrained to a certain extent.
As will be appreciated by one skilled in the art, embodiments of the present application may be provided as a method, system, or computer program product. Accordingly, the present application may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Furthermore, the present application may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, and the like) having computer-usable program code embodied therein.
The present application is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the application. It will be understood that each flow and/or block of the flow diagrams and/or block diagrams, and combinations of flows and/or blocks in the flow diagrams and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
The above description is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, several modifications and variations can be made without departing from the technical principle of the present invention, and these modifications and variations should also be regarded as the protection scope of the present invention.
Claims (10)
1. A reactive power reverse control system of a weak sending end system FC-TCR SVC (static var compensator), which is applied to the situation of restraining failure of direct current commutation, is characterized by comprising the following components: the device comprises a voltage and current measuring module (1), an isolation module I (2), a signal filtering calculation module (3), a communication module (4), a man-machine interaction module (5), a microprocessor control module (6), an isolation module II (7), an isolation module III (8), an opening and closing control module (9), a thyristor trigger module (10), a thyristor (11) and a switch (12);
the device comprises a voltage and current measuring module (1), an isolation module I (2), a signal filtering calculation module (3), a microprocessor control module (6), an isolation module III (8), an opening and closing control module (9) and a switch (12) which are sequentially connected; the microprocessor control module (6), the isolation module II (7), the thyristor trigger module (10) and the thyristor (11) are connected in sequence; the signal filtering calculation module (3) is respectively connected with the communication module (4) and the human-computer interaction module (5); the human-computer interaction module (5) is connected with the microprocessor control module (6);
the voltage and current measuring module (1) is used for acquiring voltage and current data of an FC-TCR type SVC grid-connected point from a power grid and transmitting the voltage and current data to the isolating module I (2);
the isolation module I (2) realizes the isolation of a secondary system, converts a strong current signal into a weak current signal and transmits the weak current signal to the signal filtering calculation module (3);
the signal filtering calculation module (3) is used for processing voltage and current data, has the functions of filtering and effective value calculation, and transmits the obtained signals to the communication module (4), the human-computer interaction module (5) and the microprocessor control module (6);
the communication module (4) is used for realizing remote transmission of the obtained signals;
the human-computer interaction module (5) comprises a keyboard, a display and a conversion interface, and is used for setting parameters, displaying data and states of the system in real time and realizing serial communication between the system and an upper computer;
the microprocessor control module (6) completes calculation of the conduction angle of the thyristor and switching control of the capacitor according to information input by the signal filtering calculation module 3 and the human-computer interaction module (5), the signal of the conduction angle of the thyristor is output to the isolation module II (7), and the switching control signal of the capacitor is output to the isolation module III (8), so that control over the SVC primary system is realized;
the input end of the isolation module II (7) is connected with the thyristor control output end of the microprocessor control module (6), weak current signals are converted into strong current signals, and the strong current signals are transmitted to the thyristor trigger module (10), so that the isolation of a secondary system is realized;
the input end of the isolation module III (8) is connected with the capacitor switching control signal output end of the microprocessor control module (6), weak current signals are converted into strong current signals, and the strong current signals are transmitted to the switching control module (9) to realize primary and secondary system isolation;
the input end of the switching control module (9) is connected with the output end of the isolation module III (8), and the switch of the fixed capacitor is controlled according to an input signal;
the input end of the thyristor trigger module (10) is connected with the second isolation module (7), and the conduction angle of the thyristor is controlled according to the input signal.
2. The reactive power reactive control system for SVC of the weak sending end system FC-TCR type according to claim 1, characterized in that the isolation module one (2) is composed of a Hall voltage transformer for measuring the SVC terminal voltage and a photoelectric isolation circuit, wherein the Hall voltage sensor is of the HVS5-25A type and is provided with a primary limiting resistor R1Characterized as follows:
R1＝U1/IP-Rin
in the formula R1Is a primary side current limiting resistor, U1To maximum measurement voltage, IPFor rating input current, R, of mutual inductorinIs the internal resistance of the primary side of the mutual inductor;
the photoelectric isolation circuit adopts a double-path photoelectric coupling chip with the model of TLP521-2, two paths of completely symmetrical and independent optocouplers with completely consistent physical characteristics are packaged in the photoelectric isolation circuit, and each optocoupler comprises a light emitting diode and a phototriode;
when a forward voltage is applied to two ends of a light emitting diode in the optocoupler, the light emitting diode is conducted and emits light, a photosensitive surface of the phototriode is irradiated by the light, and if the forward voltage is applied between an emitter and a collector of the phototriode, the triode has a collector current output.
3. The reactive power reactive control system for SVC of the weak sending end system FC-TCR type according to claim 2 characterized in that the rated input current I of the Hall voltage transformerPIs 5mA, the maximum voltage U is measured1Is 5V, the primary side current limiting resistor R1The output voltage U of the Hall voltage transformer is selected to be 360 omega0And the measured maximum voltage U1Are considered to be equal.
4. The reactive power reactive control system for SVC of FC-TCR type of weak sending end system according to claim 1, characterized in that the switch (12) is connected to a fixed capacitor switch, which comprises two level comparators, a sample holder 1, a sample controller, a sample holder 2, two monostable flip-flops, a slope determination module, and an AND gate, wherein one of the two level comparators is connected to one of the two monostable flip-flops and then connected to the AND gate, and the AND gate outputs a signal to the other monostable flip-flop; the other of the two level comparators is directly connected to the AND gate;
the input signal of the fixed capacitor switch comes from a human-computer interaction module (5) and a signal processing module, and the signal processing module inputs the effective value signal of the output voltage to the fixed capacitor switch.
5. The reactive power reactive control system for SVC of FC-TCR type of weak sending end system of claim 4, wherein said slope determination module is composed of two level comparators and an AND gate, and the input signals thereof are from the sample holder 1, the sample holder 2 and the signal processing module, the signal input from said signal processing module to the fixed capacitor switch is the effective value signal of the output voltage of the signal processing module, and said slope determination module outputs the level signal to the AND gate of the fixed capacitor switch.
6. The FC-TCR type SVC reactive power feedback control system of the weak sending end system as claimed in claim 4, wherein the level comparator is composed of an operational amplifier and a Schmitt trigger, the Schmitt trigger adopts a 555 timing chip, the output of the operational amplifier is connected to pins 2 and 6 of the 555 timing chip, and a pull-up resistor R is connected to pin 7 of the 555 timing chip;
the monostable trigger adopts a 555 timing chip, and pins 6 and 7 of the 555 timing chip are connected with pull-up resistors R1The 6 th pin and the 7 th pin are also connected with a decoupling capacitor C1The 5 th pin is connected with a decoupling capacitor C2。
7. The reactive feedback control system for SVC of the weak sending end system FC-TCR type according to claim 4, characterized in that the sample holder is constructed by cascading 3 LF398 chips, wherein the output terminal pin 5 of the 1 st LF398 chip is connected to the input terminal pin 3 of the 2 nd LF398 chip, and the output terminal pin 5 of the 2 nd LF398 chip is connected to the input terminal pin 3 of the 3 rd LF398 chip;
and the control end 8 pin of the 1 st LF398 chip and the control end 8 pin of the 3 rd LF398 chip are both accessed into an external sampling control signal, and meanwhile, the sampling control signal is accessed into the control end 8 pin of the 2 nd LF398 chip after passing through the NOT gate.
8. The reactive power reactive control system for SVC of FC-TCR type of weak sending end system of claim 7, wherein said sampling control signal is generated as a periodic square wave signal using 3140 operator chip.
9. The FC-TCR type SVC reactive power feedback control system of the weak sending end system of claim 1, wherein the isolation module III (8) adopts a double-path photoelectric coupling chip with the model of TLP521-2, and can convert weak electric signals of the control system into strong electric signals;
the external switching signal passes through a resistor R3A 1 st pin connected to the TLP521-2 to drive the light emitting diode in the TLP521-2 to emit light, a collector and an emitter of a phototransistor in the TLP521-2 after receiving light are turned on, a 7 th pin of the TLP521-2 outputs a level lower than a power supply voltage VCC-2, and a resistor R is connected in series between the 7 th pin of the TLP521-2 and ground2。
10. A control method using the FC-TCR type SVC reactive power reactive control system of the weak sending end system as claimed in any one of claims 1 to 9, the method is applied in the case of suppressing a direct current commutation failure fault, and is characterized in that the voltage state of the sending end alternating current system bus during the commutation failure fault and after the fault is over is divided into: a voltage reduction stage, a voltage recovery stage and a voltage stabilization stage;
in the voltage reduction stage, when the voltage of the FC-TCR type SVC access point is detected to be lower than a certain value, the initial condition of starting control of a control system is met, and the SVC control method is kept unchanged; in the voltage recovery stage, when the voltage recovery of the FC-TCR type SVC access point is detected to be more than a certain value and the change rate of the effective voltage value is positive, the fixed capacitor is disconnected; in the voltage stabilization stage, after the voltage of the access point is recovered to be stable, the fixed capacitors are put into operation in a grading manner;
the method specifically comprises the following steps:
the first step is as follows: collecting an FC-TCR type SVC grid-connected point voltage instantaneous value, and solving a real-time voltage effective value;
the second step is that: judging whether the effective value of the voltage is lower than the minimum voltage set value or not;
the third step:when the effective value of the voltage is higher than the minimum voltage set value, returning to the step two, and when the effective value of the voltage is lower than the minimum voltage set value, recording the moment T1And go to the fourth step;
the fourth step: input real-time voltage effective value UrmsValue of sample and holder U1、U2And the current time T2;
the fifth step: when T is not satisfied2-T1<TmaxWhen T is satisfied, the logic judgment is ended2-T1<TmaxTurning to the sixth step;
and a sixth step: when U is not satisfiedrms>UmaxAnd U1<U2<UrmsIn any condition, go to step four, when Urms>UmaxAnd U1<U2<UrmsWhen the two conditions are simultaneously met, turning to the step seven;
the seventh step: by switching off the fixed capacitor switch, with a delay of TminAnd closing the fixed capacitor switch after the millisecond, and finishing the switching control.
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