CN111725816B - FC-TCR SVC reactive power reverse regulation control system and method for weak transmitting end system - Google Patents
FC-TCR SVC reactive power reverse regulation control system and method for weak transmitting 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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- 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
- Y02E40/10—Flexible AC transmission systems [FACTS]
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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
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/60—Arrangements for transfer of electric power between AC networks or generators via a high voltage DC link [HVCD]
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Abstract
The invention provides a control system and a control method for inhibiting FC-TCR type SVC reactive power back regulation of a weak transmitting end system under a direct current commutation failure fault, wherein the system comprises the following components: the system comprises a voltage and current measuring module, a signal filtering and calculating 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. The method comprises the steps of obtaining FC-TCR type SVC grid-connected bus voltage data, and dividing the phase change failure fault period and the bus voltage state of a sending end alternating current system after the fault is ended into: a voltage drop stage: when the FC-TCR type SVC access point voltage is detected to be lower than a certain value, the initial condition of control starting is met, and the FC-TCR type SVC control method is kept unchanged; voltage recovery phase: when the FC-TCR type SVC access point voltage is detected to be recovered to be more than a certain value and the change rate of the effective voltage value is positive, disconnecting the fixed capacitor; voltage stabilization phase: after the voltage of the access point is restored to be stable, the fixed capacitor is put into operation in a grading manner.
Description
Technical Field
The invention relates to an FC-TCR type SVC reactive power reverse regulation 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 electric power automation.
Background
The high-voltage direct-current transmission technology is widely applied to the 'western electric eastern transmission' project of China, and the technology enables the development and the digestion of clean energy in the 'three north' areas of China to be possible. The research shows that the reactive power fluctuation caused by commutation failure causes the power grid voltage at the transmitting end to change drastically due to the relative weakness of the direct current transmitting system containing high-proportion new energy sources: when the commutation fails, a direct current side short circuit is caused, the direct current is rapidly increased, the reactive power consumed by the rectifying side converter is instantaneously increased in the period, and the voltage of the rectifying side alternating current bus is reduced; the rectifier station is generally provided with a current control link, and the function of the rectifier station is to enable direct current to be rapidly reduced and even reduced to zero, so that redundant reactive power sent by a filter arranged on the side of the converter station is completely injected into an alternating current power grid on the rectifier side, transient overvoltage occurs, unordered grid disconnection of new energy can be even caused under severe conditions, and stable operation of the power grid is seriously threatened.
Dynamic reactive compensation is crucial to safe and stable operation of a power grid, a large number of static reactive compensators (Static Var Compensator, SVC) are arranged in a new energy station of which the direct current transmission end system is put into operation, but research shows that the dynamic reactive compensation such as FC-TCR type SVC and the like arranged in the new energy station has a reverse regulation characteristic, and generates phase-lag reactive power at low voltage; when the fault is cleared and the system is over-voltage, the phase-entering reactive power cannot immediately keep up, and still generates phase-stagnating reactive power, so that the over-voltage is raised. Reactive reverse regulation characteristics of the FC-TCR type SVC are unfavorable for safe and stable operation of the system, and therefore, corresponding inhibition measures are necessary to be formulated for the reactive reverse regulation characteristics of the FC-TCR type SVC.
Disclosure of Invention
Aiming at the problems, the invention provides a FC-TCR type SVC reactive power reverse regulation control system and method for a weak transmitting end system under the fault of DC commutation failure.
According to one aspect of the present invention, there is provided an FC-TCR SVC reactive power reverse control system for a weak-power-transmission-side system, which is applied to a situation of suppressing a dc 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 and calculating 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 triggering 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 connected in sequence; the microprocessor control module (6), the isolation module II (7), the thyristor triggering 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 man-machine interaction module (5); the man-machine interaction module (5) is connected with the microprocessor control module (6);
the voltage and current measurement module (1) is used for acquiring voltage and current data of an FC-TCR SVC grid-connected point from a power grid and transmitting the data to the isolation module I (2);
the first isolation module (2) realizes secondary system isolation, converts strong electric signals into weak electric signals, and transmits the weak electric signals to the signal filtering calculation module (3);
the signal filtering calculation module (3) is used for processing voltage and current data, has functions of filtering and effective value calculation, and transmits the obtained signals to the communication module (4), the man-machine interaction module (5) and the microprocessor control module (6);
the communication module (4) is used for realizing remote transmission of the obtained signals;
the man-machine interaction module (5) comprises a keyboard, a display and a conversion interface, and is used for setting parameters and displaying data and states of the system in real time, so that serial communication between the system and an upper computer is realized;
the microprocessor control module (6) completes the calculation of the conduction angle of the thyristor and the switching control of the capacitor according to the information input by the signal filtering calculation module 3 and the man-machine 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 the control of the SVC primary system is realized;
the input end of the second isolation module (7) is connected with the thyristor control output end of the microprocessor control module (6), and weak current signals are converted into strong electric signals and are transmitted to the thyristor trigger module (10) to realize secondary system isolation;
the input end of the isolation module III (8) is connected with the output end of the capacitor switching control signal of the microprocessor control module (6), and the weak current signal is converted into a strong electric signal and is transmitted to the opening and closing control module (9) to realize secondary system isolation;
the input end of the opening and closing 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 triggering 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 for measuring SVC terminal voltage and a photoelectric isolation circuit, wherein the model of the Hall voltage sensor is HVS5-25A, and a primary current limiting resistor R is configured 1 The characterization is as follows:
R 1 ＝U 1 /I P -R in
wherein R is 1 For primary current-limiting resistor, U 1 For maximum measurement voltage, I P Rated input current for mutual inductor, R in Is the primary internal resistance of the transformer;
the photoelectric isolation circuit adopts a double-path photoelectric coupling chip with the model of TLP521-2, two paths of completely symmetrical, independent and completely consistent in physical characteristics are packaged in the photoelectric isolation circuit, and each path of photoelectric coupling comprises a light emitting diode and a phototriode;
when the forward voltage is applied to the two ends of the light emitting diode in the optocoupler, the light emitting diode is conducted and emits light, the light sensitive surface of the phototriode is irradiated by light, and if the forward voltage is applied between the emitting stage and the collector of the triode, the triode outputs collector current.
Further preferably, the hall voltage transformer has a rated input current I P At 5mA, the maximum voltage U 1 5V, the primary side current limiting resistor R 1 The output voltage U of the Hall voltage transformer is selected to be 360 omega 0 With the maximum voltage U 1 Are considered equal.
Preferably, the switch (12) is connected to a fixed capacitor switch, and the fixed capacitor switch comprises two level comparators, a sample holder 1, a sample controller, a sample holder 2, two monostable triggers, a slope judging module and an and gate, wherein one of the two level comparators is connected with one of the two monostable triggers and then connected to the and gate, and the and gate outputs a signal to the other monostable trigger; the other of the two level comparators is directly connected to the and gate;
the input signals of the fixed capacitor switch come from a man-machine interaction module (5) and a signal processing module, and the signal processing module inputs effective value signals of output voltage to the fixed capacitor switch.
More preferably, the slope judging module is composed of two level comparators and an and gate, the input signals of the slope judging module are from the sampling holder 1, the sampling holder 2 and the signal processing module, the signal input to the fixed capacitor switch by the signal processing module is an effective value signal of the output voltage of the signal processing module, and the slope judging 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 pin 7 of the 555 timing chip; the monostable trigger adopts a 555 timing chip, and the 6 th and 7 th pins of the 555 timing chip are connected with a pull-up resistor R 1 The 6 th and 7 th pins are also connected with decoupling capacitor C 1 The 5 th pin is connected with a decoupling capacitor C 2 。
Further preferably, the sample holder is constructed by cascading 3 LF398 chips, where the output terminal 5 pin of the 1 st LF398 chip is connected to the input terminal 3 pin of the 2 nd LF398 chip, and the output terminal 5 pin of the 2 nd LF398 chip is connected to the input terminal 3 pin of the 3 rd LF398 chip; the control end 8 pin of the 1 st LF398 chip and the control end 8 pin of the 3 rd LF398 chip are connected with external sampling control signals, and meanwhile, the sampling control signals are connected with the control end 8 pin of the 2 nd LF398 chip through a NOT gate.
Preferably, the sampling control signal is generated by 3140 arithmetic unit chip and is a square wave signal with a certain period.
Preferably, the isolation module III (8) adopts a double-path photoelectric coupling chip with the model of TLP521-2, and can convert weak current signals of a control system into strong electric signals; the external switch signal passes through the resistor R 3 The 1 st leg of the TLP521-2 is connected to drive the light emitting diode in the TLP521-2 to emit light, the base end of the phototransistor in the TLP521-2 is connected between the collector and the emitter after receiving light, the 7 th leg of the TLP521-2 outputs a level lower than the power supply voltage VCC-2, and a resistor R is connected in series between the 7 th leg of the TLP521-2 and the ground 2 。
According to another aspect of the present invention, a control method using the control system is provided, where the method is applied to suppressing a dc commutation failure fault, and the voltage state of the ac system bus at the transmitting end during and after the commutation failure fault is divided into: a voltage drop stage, a voltage recovery stage and a voltage stabilization stage;
in the voltage drop stage, when the FC-TCR type SVC access point voltage 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 of the FC-TCR type SVC access point is detected to be recovered to be more than a certain value and the change rate of the effective voltage value is positive, disconnecting the fixed capacitor;
and in the voltage stabilization stage, after the voltage of the access point is restored to be stable, the fixed capacitor is put into operation in a grading manner.
Further, the control method includes the steps of:
the first step: collecting the voltage instantaneous value of the FC-TCR type SVC grid-connected point, and calculating the real-time voltage effective value;
and a second step of: judging whether the voltage effective value is lower than a minimum voltage set value;
and a third step of: when the voltage effective value is higher than the minimum voltage set value, returning to the second step, and when the voltage effective value is lower than the minimum voltage set value, recording the moment T1, and turning to the fourth step;
fourth step: inputting a real-time voltage effective value Urms, values U1 and U2 of a sampling holder and a current time T2;
fifth step: ending the logic judgment when T2-T1< Tmax is not satisfied, and turning to the sixth step when T2-T1< Tmax is satisfied;
sixth step: when either condition of Urms > Umax and U1< U2< Urms is not satisfied, go to step four, and when both conditions of Urms > Umax and U1< U2< Urms are satisfied at the same time, go to step seven;
seventh step: the fixed capacitor switch is turned off, and after the time delay is Tmin milliseconds, the fixed capacitor switch is turned on, and the switching control is finished.
Advantageous effects of the invention
According to the method, the voltage state of the grid-connected point of the FC-TCR type SVC is divided into three stages according to the voltage change rule of the weak power grid caused by commutation failure, and logic judgment is carried out on each stage, so that the switching operation of the capacitor is controlled, the reactive reverse regulation phenomenon of the FC-TCR type SVC is effectively restrained, and the risk of high-voltage grid-off of new energy sources of the power grid-connected system is reduced.
Drawings
FIG. 1 is a block diagram of a control system of the present invention;
FIG. 2 is a circuit diagram of an isolation module;
FIG. 3 is a flow chart of a method of fixed capacitor switch control;
FIG. 4 is a schematic block diagram of a 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 graph comparing voltage curves of SVC grid-connected points.
Reference numerals:
1-a voltage current measurement module;
2-isolation Module I
3-signal filtering calculation module
4-communication module
5-man-machine interaction module
6-microprocessor control module
7-isolation module II
8-isolation module III
9-open/close 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 reverse regulation control system for a weak transmitting end system under a direct current commutation failure inhibiting fault, which is shown in fig. 1, wherein 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 triggering 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 man-machine 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 model of the hall voltage sensor for measuring the voltage of an SVC terminal is HVS5-25A, and a primary current limiting resistor is configured:
R 1 ＝U 1 /I P -R in
wherein R is 1 For primary current-limiting resistor, U 1 For maximum measurement voltage, I P Rated input current for mutual inductor, R in Is the internal resistance of the primary side of the transformer.
As the Hall sensor requires the rated input current of the primary side to be about 5mA, the maximum voltage U is measured 1 The primary current limiting resistor R is selected because of the ratio of =5V 1 The method comprises the following steps:
R 1 ＝5V/5mA-650＝350Ω
r is taken according to the actual resistance value of the resistor 1 =360 Ω, selecting the output voltage as U o =5v, and then according to the turns ratio, there is the formula:
obtaining: r is R m ＝200Ω
So that the output voltage U o And the measured voltage U 1 The actual relationship between the two is:
the photoelectric isolation circuit adopts a double-path photoelectric coupling chip with the model of TLP521-2, and two paths of completely symmetrical, independent and completely consistent optical couplers with physical characteristics are packaged inside the photoelectric isolation circuit. When the forward voltage is applied to the two ends of the light emitting diode, the diode is conducted and emits light, the light sensitive surface of the phototriode is irradiated by light, and if the forward voltage is applied between the emitter and the collector of the triode, the collector current of the triode is output.
Fig. 3 is a flow chart of a method for controlling a fixed capacitor switch, specifically including the following steps:
the first step: collecting the voltage instantaneous value of the FC-TCR type SVC grid-connected point, and calculating the real-time voltage effective value;
and a second step of: judging whether the voltage effective value is lower than a minimum voltage set value;
and a third step of: when the effective voltage value is higher than the minimum voltage set value, returning to the second step, and when the effective voltage value is lower than the minimum voltage set value, recording the moment T 1 And transferring to a fourth step;
fourth step: inputting real-time voltage effective value U rms Value U of sample holder 1 、U 2 A current time T2;
fifth step: when not meeting T 2 -T 1 <T max When T is satisfied, logic judgment is ended 2 -T 1 <T max Turning to a sixth step;
sixth step: when not meeting U rms >U max And U 1 <U 2 <U rms Under any condition, go to step four, when U rms >U max And U 1 <U 2 <U rms When the two conditions are met simultaneously, turning to a step seven;
seventh step: the fixed capacitor switch is turned off, and the time delay T is prolonged min After millisecond, the fixed capacitor switch is closed, and the switching control is finished.
Fig. 4 is a schematic diagram of a fixed capacitor switch control, which is composed of a level comparator, a sample holder, a monostable trigger, a slope judging module and the like, wherein an input signal of the fixed capacitor switch control is from a man-machine interaction module and a signal processing module.
Fig. 5 is a schematic diagram of a slope judging module, which is composed of a level comparator and an and gate, and the input signal of the slope judging module is 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 the pin 7 of the 555 timing chip is pulled up to a resistor.
FIG. 7 is a circuit diagram of a monostable flip-flop employing a 555 timer chip, the 6 th and 7 th pins of the 555 timer chip being connected to a pull-up resistor R 1 6 th and 7 thThe foot is also connected with a decoupling capacitor C 1 The 5 th pin is connected with the decoupling capacitor C2.
Fig. 8 is a circuit diagram of a sample-and-hold device, in which 3 LF398 chips are cascaded, and the output terminal 5 pin of the 1 st LF398 chip is connected to the input terminal 3 pin of the 2 nd LF398 chip, and the output terminal 5 pin of the 2 nd LF398 chip is connected to the input terminal 3 pin of the 3 rd LF398 chip. The control end 8 pin of the 1 st LF398 chip and the control end 8 pin of the 3 rd LF398 chip are connected with external sampling control signals, and meanwhile, the sampling control signals are connected with the control end 8 pin 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 3140 chips to let R 1 ＝R 2 The circuit can generate a square wave signal with a period of T, and the period calculation formula is as follows:
T＝R 1 C+R 2 C
FIG. 10 shows an optoelectric isolation circuit, which employs a two-way optoelectric coupling chip with the model TLP521-2, and two paths of optocouplers which are completely symmetrical, independent and completely consistent in physical characteristics are packaged inside the optoelectric isolation circuit. When the forward voltage is applied to the two ends of the light emitting diode, the diode is conducted and emits light, the light sensitive surface of the phototriode is irradiated by light, and if the forward voltage is applied between the emitter and the collector of the triode, the collector current of the triode is output.
FIG. 11 is a three-circuit diagram of an isolation module, which uses a two-way optocoupler chip of the type TLP521-2 to convert weak current signals of a control system into strong current signals. The external switch signal passes through the resistor R 3 The 1 st leg of the TLP521-2 is connected to drive the light emitting diode to emit light, the base end of the photo transistor is conducted between the collector and the emitter after receiving light, the 7 th leg of the TLP521-2 outputs a level slightly lower than the power supply voltage VCC-2, and a resistor R is connected in series between the 7 th leg of the TLP521-2 and the ground for preventing overcurrent 2 。
Fig. 12 is a graph comparing voltage curves of SVC grid-connected points, based on a cigle direct current transmission model, an FC-TCR SVC is provided in a transmitting-end ac system, and a transmitting-end ac grid voltage waveform is generated when commutation failure occurs at an inversion side. The graph shows that the overvoltage of the FC-TCR type SVC grid-connected bus in the transient period is inhibited to a certain extent after the control method is adopted.
It will be appreciated by those skilled in the art that 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 flowchart illustrations and/or block diagrams, and combinations of flows and/or blocks in the flowchart illustrations 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 foregoing is merely a preferred embodiment of the present invention, and it should be noted that modifications and variations could be made by those skilled in the art without departing from the technical principles of the present invention, and such modifications and variations should also be regarded as being within the scope of the invention.
Claims (10)
1. The FC-TCR SVC reactive power reverse regulation control system of the weak transmitting end system is applied to the situation of inhibiting direct current commutation failure faults, 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 and calculating 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 triggering 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 connected in sequence; the microprocessor control module (6), the isolation module II (7), the thyristor triggering 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 man-machine interaction module (5); the man-machine interaction module (5) is connected with the microprocessor control module (6);
the voltage and current measurement module (1) is used for acquiring voltage and current data of an FC-TCR SVC grid-connected point from a power grid and transmitting the data to the isolation module I (2);
the first isolation module (2) realizes secondary system isolation, converts strong electric signals into weak electric signals, and transmits the weak electric signals to the signal filtering calculation module (3);
the signal filtering calculation module (3) is used for processing voltage and current data, has functions of filtering and effective value calculation, and transmits the obtained signals to the communication module (4), the man-machine interaction module (5) and the microprocessor control module (6);
the communication module (4) is used for realizing remote transmission of the obtained signals;
the man-machine interaction module (5) comprises a keyboard, a display and a conversion interface, and is used for setting parameters and displaying data and states of the system in real time, so that serial communication between the system and an upper computer is realized;
the microprocessor control module (6) completes the calculation of the conduction angle of the thyristor and the switching control of the capacitor according to the information input by the signal filtering calculation module 3 and the man-machine 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 the control of the SVC primary system is realized;
the input end of the second isolation module (7) is connected with the thyristor control output end of the microprocessor control module (6), and weak current signals are converted into strong electric signals and are transmitted to the thyristor trigger module (10) to realize secondary system isolation;
the input end of the isolation module III (8) is connected with the output end of the capacitor switching control signal of the microprocessor control module (6), and the weak current signal is converted into a strong electric signal and is transmitted to the opening and closing control module (9) to realize secondary system isolation;
the input end of the opening and closing 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 triggering 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 weak power transmission end system FC-TCR type SVC reactive power reverse regulation system according to claim 1, wherein the isolation module I (2) is composed of a Hall voltage transformer for measuring SVC end voltage and a photoelectric isolation circuit, wherein the Hall voltage sensor is of the type HVS5-25A, and a primary current limiting resistor R is configured 1 The characterization is as follows:
R 1 ＝U 1 /I P -R in
wherein R is 1 For primary current-limiting resistor, U 1 For maximum measurement voltage, I P Rated input current for mutual inductor, R in Is the primary internal resistance of the transformer;
the photoelectric isolation circuit adopts a double-path photoelectric coupling chip with the model of TLP521-2, two paths of completely symmetrical, independent and completely consistent in physical characteristics are packaged in the photoelectric isolation circuit, and each path of photoelectric coupling comprises a light emitting diode and a phototriode;
when the forward voltage is applied to the two ends of the light emitting diode in the optocoupler, the light emitting diode is conducted and emits light, the light sensitive surface of the phototriode is irradiated by light, and if the forward voltage is applied between the emitting stage and the collector of the triode, the triode outputs collector current.
3. The weak feed end system FC-TCR type SVC reactive power reverse regulation system according to claim 2, wherein the rated input current I of the Hall voltage transformer is characterized in that P At 5mA, the maximum voltage U 1 5V, the primary side current limiting resistor R 1 The output voltage U of the Hall voltage transformer is selected to be 360 omega 0 With the maximum voltage U 1 Are considered equal.
4. A weak link system FC-TCR type SVC reactive reverse regulation system according to claim 1, characterized in that the switch (12) is connected to a fixed capacitor switch, the fixed capacitor switch comprising two level comparators, a sample holder 1, a sample controller, a sample holder 2, two monostable triggers, a slope judgment module, and an and gate, one of the two level comparators being connected to one of the two monostable triggers before being connected to the and gate, the and gate outputting a signal to the other monostable trigger; the other of the two level comparators is directly connected to the and gate;
the input signals of the fixed capacitor switch come from a man-machine interaction module (5) and a signal processing module, and the signal processing module inputs effective value signals of output voltage to the fixed capacitor switch.
5. The FC-TCR type SVC reactive power reverse control system of claim 4, wherein the slope judging module comprises two level comparators and an and gate, the input signals of the slope judging module are from the sample holder 1, the sample holder 2 and the signal processing module, the signal input to the fixed capacitor switch by the signal processing module is an effective value signal of the output voltage of the signal processing module, and the slope judging module outputs the level signal to the and gate of the fixed capacitor switch.
6. The FC-TCR SVC reactive power reverse control system of weak transmitting end system according to 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 the 2 nd and 6 th pins of the 555 timing chip, and the 7 th pin of the 555 timing chip is connected with a pull-up resistor R;
the monostable trigger adopts a 555 timing chip, and the 6 th and 7 th pins of the 555 timing chip are connected with a pull-up resistor R 1 The 6 th and 7 th pins are also connected with decoupling capacitor C 1 The 5 th pin is connected with a decoupling capacitor C 2 。
7. The weak feed end system FC-TCR type SVC reactive power reaction control system according to claim 4, wherein the sampling holder is constructed by cascading 3 LF398 chips, wherein the output end 5 pin of the 1 st LF398 chip is connected with the input end 3 pin of the 2 nd LF398 chip, and the output end 5 pin of the 2 nd LF398 chip is connected with the input end 3 pin of the 3 rd LF398 chip;
the control end 8 pin of the 1 st LF398 chip and the control end 8 pin of the 3 rd LF398 chip are connected with external sampling control signals, and meanwhile, the sampling control signals are connected with the control end 8 pin of the 2 nd LF398 chip through a NOT gate.
8. The FC-TCR type SVC reactive power reverse control system of claim 7, wherein the sampling control signal is a periodic square wave signal generated by 3140 arithmetic chip.
9. The FC-TCR SVC reactive power reverse control system of the weak transmitting end system according to claim 1, wherein the isolation module III (8) adopts a double-circuit photoelectric coupling chip with the model of TLP521-2, and can convert weak current signals of the control system into strong electric signals;
the external switch signal passes through the resistor R 3 The 1 st leg of the TLP521-2 is connected to drive the light emitting diode in the TLP521-2 to emit light, the base end of the phototransistor in the TLP521-2 is connected between the collector and the emitter after receiving light, the 7 th leg of the TLP521-2 outputs a level lower than the power supply voltage VCC-2, and a resistor R is connected in series between the 7 th leg of the TLP521-2 and the ground 2 。
10. A control method for applying the FC-TCR SVC reactive power reverse regulation control system of the weak transmitting end system according to any one of claims 1-9, which is applied to the situation of inhibiting direct current commutation failure, and is characterized in that the bus voltage state of the transmitting end alternating current system during and after the commutation failure is divided into: a voltage drop stage, a voltage recovery stage and a voltage stabilization stage;
in the voltage drop stage, when the FC-TCR type SVC access point voltage 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 of the FC-TCR type SVC access point is detected to be recovered to be more than a certain value and the change rate of the effective voltage value is positive, disconnecting the fixed capacitor; in the voltage stabilization stage, after the voltage of the access point is restored to be stable, the fixed capacitor is put into operation in a grading manner;
the method specifically comprises the following steps:
the first step: collecting the voltage instantaneous value of the FC-TCR type SVC grid-connected point, and calculating the real-time voltage effective value;
and a second step of: judging whether the voltage effective value is lower than a minimum voltage set value;
and a third step of: when the voltage effective value is higher than the minimum voltage set value, the step is returned toStep two, when the effective voltage value is lower than the minimum voltage set value, recording the time T 1 And transferring to a fourth step;
fourth step: inputting real-time voltage effective value U rms Value U of sample holder 1 、U 2 A current time T2;
fifth step: when not meeting T 2 -T 1 <T max When T is satisfied, logic judgment is ended 2 -T 1 <T max Turning to a sixth step;
sixth step: when not meeting U rms >U max And U 1 <U 2 <U rms Under any condition, go to step four, when U rms >U max And U 1 <U 2 <U rms When the two conditions are met simultaneously, turning to a step seven;
seventh step: the fixed capacitor switch is turned off, and the time delay T is prolonged min After millisecond, the fixed capacitor switch is closed, and the switching control is finished.
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