CN109459633B - Method, device and system for diagnosing fault of thyristor-level circuit of direct-current transmission converter valve - Google Patents
Method, device and system for diagnosing fault of thyristor-level circuit of direct-current transmission converter valve Download PDFInfo
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Abstract
The invention discloses a method, a device and a system for diagnosing faults of a thyristor-level loop of a direct-current transmission converter valve, wherein the fault diagnosis method comprises the following steps: obtaining a first running state of the voltage-sharing circuit according to a first sampling current of the voltage-sharing circuit in the turn-off state of the thyristor and a first voltage at two ends of the voltage-sharing circuit at a first sampling moment; obtaining a second running state of the damping resistor according to a second sampling current of the damping resistor and a second voltage at two ends of the damping resistor at a second sampling moment; obtaining a third running state of the damping capacitor according to a third sampling current discharged by the damping capacitor and third voltages at two ends of the damping capacitor at least two third sampling moments; and determining the operation state of the thyristor-level loop of the direct-current transmission converter valve based on the first operation state, the second operation state and the third operation state. The invention can accurately detect the states of the voltage-sharing loop and the damping loop in real time on line, and provides a basis for monitoring the working state of the whole converter valve and pre-judging faults.
Description
Technical Field
The invention relates to the technical field of power electronics and power systems, in particular to a method, a device and a system for diagnosing a thyristor-level loop fault of a direct-current transmission converter valve.
Background
The thyristor-level loop of the high-voltage direct-current converter valve is formed by serially connecting key components such as a thyristor, a thyristor trigger monitoring system, a damping loop, a voltage-sharing loop and the like, wherein the damping loop and the voltage-sharing loop are used for reducing the phase-change voltage overshoot of the converter valve during the turn-off recovery period of the thyristor and simultaneously play a role in statically and dynamically sharing the voltage of the serially connected thyristor, thereby protecting the thyristor from being damaged by turn-off overvoltage and keeping the voltage uniformly distributed. If the elements of the damping circuit and the voltage-sharing circuit are damaged, a thyristor trigger monitoring system (a thyristor trigger detection device) cannot obtain energy required by work, and further cannot measure thyristor level voltage, so that normal triggering and overvoltage protection triggering functions are lost, and a corresponding thyristor is possibly damaged by overvoltage breakdown.
At present, methods for monitoring the operating parameters of damping loop and voltage-sharing loop elements and other key components in real time at home and abroad are still few, and the design of a specific hardware monitoring circuit is few. The operation state of the converter valve cannot be monitored in real time and the fault can not be judged in advance, the fault processing has hysteresis, and only regular maintenance can be implemented, so that the reliability and the availability of the converter valve are large in improvement space.
In summary, it is necessary to research a method capable of accurately detecting the states of the voltage-sharing circuit and the damping circuit in real time on line, so as to provide a basis for monitoring the working state of the whole converter valve and pre-judging faults.
Disclosure of Invention
In view of this, embodiments of the present invention provide a method, an apparatus, and a system for diagnosing a fault of a thyristor-level circuit of a dc transmission converter valve, so as to solve the reliability problem caused by that a fault prediction cannot be implemented on the converter valve at present and the problem of relatively low availability ratio caused by that only regular maintenance is available.
According to a first aspect, an embodiment of the present invention provides a method for diagnosing a fault of a thyristor-level circuit of a dc transmission converter valve, where the thyristor-level circuit includes a thyristor, a thyristor trigger monitoring device, a voltage-sharing circuit, and a damping circuit, and the damping circuit includes a damping resistor and a damping capacitor, and includes: obtaining a first running state of the voltage-sharing circuit according to a first sampling current of the voltage-sharing circuit in the turn-off state of the thyristor and a first voltage at two ends of the voltage-sharing circuit at a first sampling moment; obtaining a second running state of the damping resistor according to a second sampling current of the damping resistor and a second voltage at two ends of the damping resistor at a second sampling moment; obtaining a third running state of the damping capacitor according to a third sampling current discharged by the damping capacitor and third voltages at two ends of the damping capacitor at least two third sampling moments; and determining the operation state of the thyristor-level loop of the direct-current transmission converter valve based on the first operation state, the second operation state and the third operation state.
Optionally, the voltage-sharing circuit includes a dc voltage-sharing resistor, the first sampling current is obtained by sampling through the first sampling resistor, and the first sampling resistor is connected in series between a low-potential end of the dc voltage-sharing resistor and the thyristor trigger monitoring device; the obtaining of the first running state of the voltage-sharing circuit according to the first sampling current of the voltage-sharing circuit in the off state of the thyristor and the first voltage at two ends of the voltage-sharing circuit at the first sampling moment comprises: acquiring the voltage of the low potential end of the direct current voltage-sharing resistor at the first sampling moment; obtaining the first sampling current according to the voltage of the low potential end to the ground of the direct current voltage-sharing resistor and the first sampling resistor; obtaining the voltage of the high potential end of the direct current equalizing resistor at the first sampling moment according to the voltage peak values at the two ends of the thyristor and the first sampling moment; obtaining a first measurement resistance value of the direct current voltage-sharing resistor according to the first sampling current, the voltage to ground of the high potential end of the direct current voltage-sharing resistor and the voltage to ground of the low potential end of the direct current voltage-sharing resistor; and comparing the first measured resistance value with the first preset resistance value to obtain the first running state.
Optionally, the obtaining a second operating state of the damping resistor according to a second sampling current of the damping resistor and a second voltage across the damping resistor at a sampling time includes: respectively acquiring the low-potential voltage-to-ground voltage and the high-potential voltage-to-ground voltage of the damping resistor at the second sampling moment; obtaining a second sampling current according to the low-potential voltage-to-ground voltage of the damping resistor and a second sampling resistor, wherein the second sampling resistor is connected in series between the damping resistor and the thyristor trigger monitoring device; obtaining a second measurement resistance value of the damping resistor according to the second sampling current, the voltage to ground of the high-potential end of the damping resistor and the voltage to ground of the low-potential end of the damping resistor; and comparing the second measured resistance value with the second preset resistance value to obtain the second running state.
Optionally, the obtaining a third operating state of the damping capacitor according to the third sampling current discharged by the damping capacitor and the third voltages at the two ends of the damping capacitor at the at least two third sampling moments includes: respectively acquiring the low-potential voltage-to-ground voltage and the high-potential voltage-to-ground voltage of the damping resistor at the third sampling moment; obtaining a third sampling current according to the low-potential voltage-to-ground voltage of the damping resistor and a third sampling resistor, wherein the third sampling resistor is connected in series between the damping resistor and the thyristor trigger monitoring device; obtaining an impedance value of the damping capacitor according to the third sampling current and the voltage of the damping resistor high-potential end to ground; and comparing the impedance value of the damping capacitor with the preset impedance value to obtain the third running state.
According to a second aspect, an embodiment of the present invention provides a method for diagnosing a fault of a thyristor-level circuit of a dc transmission converter valve, where the thyristor-level circuit includes a thyristor, a thyristor trigger monitoring device, a voltage-sharing circuit, and a damping circuit, and includes: obtaining a first running state of the voltage-sharing circuit according to a first sampling current of the voltage-sharing circuit in the turn-off state of the thyristor and a first voltage at two ends of the voltage-sharing circuit at a first sampling moment; obtaining a fourth running state of the damping loop according to the discharging time required by the discharging current in the damping loop to be reduced from the peak value to half of the peak value when the thyristor is in the on state; and determining the operation state of the thyristor-level loop of the direct-current transmission converter valve based on the first operation state and the fourth operation state.
Optionally, the voltage-sharing circuit includes a dc voltage-sharing resistor, the first sampling current is obtained by sampling through the first sampling resistor, and the first sampling resistor is connected in series between a low-potential end of the dc voltage-sharing resistor and the thyristor trigger monitoring device; the obtaining of the first running state of the voltage-sharing circuit according to the first sampling current of the voltage-sharing circuit in the off state of the thyristor and the first voltage at two ends of the voltage-sharing circuit at the first sampling moment comprises: acquiring the voltage of the low potential end of the direct current voltage-sharing resistor at the first sampling moment; obtaining the first sampling current according to the voltage of the low potential end to the ground of the direct current voltage-sharing resistor and the first sampling resistor; obtaining the voltage of the high potential end of the direct current equalizing resistor at the first sampling moment according to the voltage peak values at the two ends of the thyristor and the first sampling moment; obtaining a first measurement resistance value of the direct current voltage-sharing resistor according to the first sampling current, the voltage to ground of the high potential end of the direct current voltage-sharing resistor and the voltage to ground of the low potential end of the direct current voltage-sharing resistor; and comparing the first measured resistance value with the first preset resistance value to obtain the first running state.
Optionally, the damping circuit is connected to a time detection circuit, the time detection circuit is configured to output a level jump when a discharge current of the damping circuit drops to a half of a peak value, the discharge current is obtained through a fourth sampling resistor, and the fourth sampling resistor is connected in series between the damping resistor and the thyristor trigger monitoring device; the obtaining of the fourth operating state of the damping loop according to the discharge duration required by the discharge current in the damping loop to decrease from the peak value to half of the peak value in the thyristor on state includes: recording a time interval from the thyristor being turned on to the output level of the time detection circuit jumping, wherein the time interval is the discharge duration; and comparing the discharge time length value with the preset time length to obtain the fourth running state.
According to a third aspect, an embodiment of the present invention provides a fault diagnosis apparatus for a thyristor-level circuit of a dc transmission converter valve, where the thyristor-level circuit includes a thyristor, a thyristor trigger monitoring device, a voltage-sharing circuit, and a damping circuit, and the damping circuit includes a damping resistor and a damping capacitor, and includes: the first state detection module is used for obtaining a first running state of the voltage-sharing circuit according to a first sampling current of the voltage-sharing circuit in the turn-off state of the thyristor and a first voltage at two ends of the voltage-sharing circuit at a first sampling moment; the second state detection module is used for obtaining a second running state of the damping resistor according to a second sampling current of the damping resistor and a second voltage at two ends of the damping resistor at a second sampling moment; the third state detection module is used for obtaining a third running state of the damping capacitor according to a third sampling current discharged by the damping capacitor and third voltages at two ends of the damping capacitor at least two third sampling moments; a first diagnostic module configured to determine an operating state of the thyristor-level circuit of the dc transmission converter valve based on the first operating state, the second operating state, and the third operating state.
According to a fourth aspect, an embodiment of the present invention provides a fault diagnosis apparatus for a thyristor-level circuit of a dc transmission converter valve, where the thyristor-level circuit includes a thyristor, a thyristor trigger monitoring device, a voltage-equalizing circuit, and a damping circuit, and includes: the first state detection module is used for obtaining a first running state of the voltage-sharing circuit according to a first sampling current of the voltage-sharing circuit in the turn-off state of the thyristor and a first voltage at two ends of the voltage-sharing circuit at a first sampling moment; the fourth state detection module is used for obtaining a fourth running state of the damping loop according to the discharging time required by the discharging current in the damping loop to be reduced from the peak value to half of the peak value when the thyristor is in the on state; and the second diagnosis module is used for determining the operation state of the thyristor-level loop of the direct-current transmission converter valve based on the first operation state and the fourth operation state.
According to a fifth aspect, an embodiment of the present invention provides a system for diagnosing a fault of a thyristor-level circuit of a dc transmission converter valve, where the system is configured to diagnose the fault of the thyristor-level circuit of the dc transmission converter valve, and is characterized by including: the method comprises a current sampling circuit, a voltage sampling circuit, a time detection circuit, a memory and a processor, wherein the current sampling circuit, the voltage sampling circuit, the time detection circuit, the memory and the processor are connected in a communication manner, the memory stores computer instructions, and the processor executes the computer instructions so as to execute the method for diagnosing the fault of the thyristor-level loop of the direct current power transmission converter valve according to the first aspect or the second aspect.
The embodiment of the invention provides a method, a device and a system for diagnosing faults of a thyristor-level loop of a direct-current transmission converter valve. The invention can lay a foundation for realizing the conversion from 'regular maintenance' to 'state maintenance' of the converter valve, solves the reliability problem caused by the failure prejudgment of the converter valve and the problem of relatively low availability ratio caused by the regular maintenance only at present, and finally improves the reliability and the availability ratio of the converter valve.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and other drawings can be obtained by those skilled in the art without creative efforts.
FIG. 1 shows a thyristor level electrical equivalent schematic in an embodiment of the invention;
fig. 2 shows a flow chart of a fault diagnosis method for a thyristor-level loop of a dc transmission converter valve according to an embodiment of the present invention;
fig. 3 is a flow chart of another method for diagnosing a fault of a thyristor-level loop of a dc transmission converter valve according to an embodiment of the present invention;
FIG. 4 illustrates a voltage grading resistor loop diagnostic schematic of an embodiment of the present invention;
FIG. 5 illustrates a damping resistor capacitance diagnostic schematic of an embodiment of the present invention;
FIG. 6 illustrates a damping capacitance discharge waveform diagram according to an embodiment of the present invention;
FIG. 7 illustrates a damping circuit diagnostic schematic of an embodiment of the present invention;
FIG. 8 shows a schematic diagram of a time detection circuit according to an embodiment of the invention.
Reference numerals:
10-a thyristor; 20-an anode heat sink; 30-a cathode heat sink; 40-direct current voltage-sharing resistance; 50-direct current voltage-sharing resistance; 60-thyristor trigger monitoring system; 70-a thyristor trigger monitoring device energy obtaining module; 80-damping capacitance; 90-damping capacitance; 100-damping capacitance; 110-damping resistance; 120-damping resistance; 130-an inverting amplifier; 140-comparator.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The invention provides a method for diagnosing the fault of a thyristor-level loop of a direct-current transmission converter valve, which is used for diagnosing the thyristor-level loop of the converter valve shown in figure 1, and the thyristor-level loop of the converter valve can comprise a thyristor 10, a direct-current voltage-sharing resistor 40, a direct-current voltage-sharing resistor 50, a damping resistor 110, a damping resistor 120, a damping capacitor 80, a damping capacitor 90, a damping capacitor 100 and a thyristor trigger monitoring device 60, wherein the anode of the thyristor 10 is connected with the first end of an anode radiator 20, the second end of the anode radiator 20 is respectively connected with the first end of the direct-current voltage-sharing resistor 40 and the first end of the damping capacitor 80, the second end of the direct-current voltage-sharing resistor 40 is connected with the first end of the direct-current voltage-sharing resistor 50, the second end of the direct-current voltage-sharing resistor 50 is connected with the thyristor trigger monitoring device 60, the second end of the damping capacitor 80 is respectively connected with the first end of the damping resistor 90 and the first end of the damping capacitor 100, the second end of the damping capacitor 90 is connected with the first end of the damping resistor 110, the second end of the damping resistor 110 is connected with the thyristor trigger detection device 60, the second end of the damping capacitor 100 is connected with the first end of the damping resistor 120, the second end of the damping resistor 120 is connected with the thyristor trigger detection device 60, the cathode of the thyristor 10 is respectively connected with the thyristor trigger detection device 60 and the first end of the cathode radiator 30, the second end of the cathode radiator 30 is connected with the thyristor trigger detection device 60, and the gate of the thyristor 10 is connected with the thyristor trigger detection device 60. The thyristor 10 belongs to a main loop of the converter valve, and the energy-taking module 70 of the thyristor trigger monitoring device takes energy from two ends of the thyristor 10 through a damping loop.
As shown in fig. 2, the diagnostic method may include:
s101, obtaining a first running state of the voltage-sharing loop according to a first sampling current of the voltage-sharing loop in the turn-off state of the thyristor and a first voltage at two ends of the voltage-sharing loop at a first sampling moment. In a specific implementation, the voltage-sharing loop comprises a direct-current voltage-sharing resistor, a first sampling current is obtained by sampling through the first sampling resistor, and the first sampling resistor is connected in series between a low-potential end of the direct-current voltage-sharing resistor and the thyristor trigger monitoring device; obtaining a first running state of the voltage-sharing circuit according to a first sampling current of the voltage-sharing circuit in the turn-off state of the thyristor and a first voltage at two ends of the voltage-sharing circuit at a first sampling moment, wherein the first running state comprises the following steps: acquiring the voltage of a low potential end of a direct current voltage-sharing resistor at a first sampling moment; obtaining a first sampling current according to the voltage of a low potential end to ground of the direct current voltage-sharing resistor and the first sampling resistor; obtaining the voltage of the high potential end of the direct current voltage-sharing resistor at the first sampling moment according to the voltage peak values at the two ends of the thyristor and the first sampling moment; obtaining a first measurement resistance value of the direct current voltage-sharing resistor according to the first sampling current, the voltage of the high potential end of the direct current voltage-sharing resistor to the ground and the voltage of the low potential end of the direct current voltage-sharing resistor to the ground; and comparing the first measured resistance value with the first preset resistance value to obtain a first running state.
S102, obtaining a second running state of the damping resistor according to a second sampling current of the damping resistor and a second voltage at two ends of the damping resistor at a second sampling moment; in a specific embodiment, a low potential voltage to ground and a high potential voltage to ground of a damping resistor at a second sampling moment are respectively obtained; obtaining a second sampling current according to the voltage of the low potential end to ground of the damping resistor and a second sampling resistor, wherein the second sampling resistor is connected in series between the damping resistor and the thyristor trigger monitoring device; obtaining a second measurement resistance value of the damping resistor according to the second sampling current, the voltage of the damping resistor high-potential end to ground and the voltage of the damping resistor low-potential end to ground; and comparing the second measured resistance value with a second preset resistance value to obtain a second running state.
And S103, obtaining a third running state of the damping capacitor according to the third sampling current discharged by the damping capacitor and the third voltages at the two ends of the damping capacitor at least two third sampling moments. In a specific embodiment, a low potential voltage to ground and a high potential voltage to ground of a damping resistor at a third sampling moment are respectively obtained; obtaining a third sampling current according to the voltage of the low potential end to ground of the damping resistor and a third sampling resistor, wherein the third sampling resistor is connected in series between the damping resistor and the thyristor trigger monitoring device; obtaining an impedance value of the damping capacitor according to the third sampling current and the voltage of the high-potential end of the damping resistor to the ground; and comparing the impedance value of the damping capacitor with a preset impedance value to obtain a third running state.
And S104, determining the operation state of the thyristor-level loop of the direct-current transmission converter valve based on the first operation state, the second operation state and the third operation state.
As shown in fig. 3, another diagnostic method may include:
s201, obtaining a first running state of the voltage-sharing loop according to a first sampling current of the voltage-sharing loop in the turn-off state of the thyristor and a first voltage at two ends of the voltage-sharing loop at a first sampling moment. Specifically, reference may be made to the description of detecting the first operation state in step S101 of the above embodiment.
S202, obtaining a fourth operation state of the damping loop according to the discharge duration required by the discharge current in the damping loop to be reduced from the peak value to half of the peak value when the thyristor is in the on state. In a specific implementation, the damping loop is connected with a time detection circuit, the time detection circuit is used for outputting level jump when the discharge voltage of the damping loop is reduced to half of a peak value, the discharge current is obtained through a fourth sampling resistor, and the fourth sampling resistor is connected in series between the damping resistor and the thyristor triggering monitoring device; obtaining a fourth operating state of the damping loop according to a discharge duration required by a discharge current in the damping loop to be reduced from a peak value to a half of the peak value in a thyristor switching-on state, wherein the fourth operating state comprises the following steps: recording a time interval from the switching-on of the thyristor to the jumping of the output level of the time detection circuit, wherein the time interval is the discharge duration; and comparing the discharge time length value with a preset time length to obtain a fourth running state.
S203, determining the operation state of the thyristor-level loop of the direct-current transmission converter valve based on the first operation state and the fourth operation state.
The following describes a method for diagnosing a fault of a thyristor-level loop of a dc transmission converter valve in detail with reference to fig. 4 to 8:
1. diagnosis of the operating state of the dc grading resistor, i.e. the first operating state: the monitoring principle of the direct current voltage-sharing resistor is to measure the voltage and the current at two ends of the resistor and then calculate the resistance value according to ohm's law. After the thyristor is turned on, the voltage across the dc voltage-sharing resistor is zero, so it needs to be measured when the thyristor is turned off. Between the forward zero crossing point and the conducting time of the voltage at two ends of the thyristor, a first sampling current flowing through the direct current voltage-sharing resistor is sampled through a first current sampling resistor, the voltage of a low potential end of the direct current voltage-sharing resistor is sampled through a resistance-capacitance voltage divider to the ground, and the peak value of sinusoidal voltage added at two ends of the thyristor is unchanged under the normal working condition, so that the voltage of the high potential end of the direct current voltage-sharing resistor can be calculated according to the first sampling time, and then a first measurement resistance value of the direct current voltage-sharing resistor is calculated through the first voltage and the first sampling current at the first sampling time.
A specific embodiment of the dc grading resistance measuring circuit is shown in fig. 4. In order to obtain a first sampling current I flowing through a DC voltage-sharing resistorjA very small resistor R is connected in series between the DC voltage-sharing resistor and the thyristor trigger detection devicesDue to the resistance RsIs very much of resistanceSmall, the influence on the current flowing on the voltage-sharing resistor can be ignored,
in order to obtain the voltage to ground at the low potential end of the DC voltage-sharing resistor, the DC voltage-sharing resistor and R are connectedsA resistance-capacitance voltage divider connected with ground in between, the resistance-capacitance voltage divider is formed by a series of series-parallel connection of resistance and capacitance, Ra、Rb、CaAnd CbSatisfies the following relationship:
and K is the voltage division ratio of the resistance-capacitance voltage divider.
Wherein the RC voltage divider can pass through the voltage UkThe voltage of the low potential end of the direct current voltage-sharing resistor is compared with the voltage division ratio to obtain the voltage of the low potential end of the direct current voltage-sharing resistor to the ground, namely the voltage Us, the voltage of the high potential end of the direct current voltage-sharing resistor is calculated by combining with the first sampling moment, the first voltage at two ends of the direct current voltage-sharing resistor at the sampling moment is obtained, potential safety hazards caused by the high voltage during direct measurement are avoided, then the first measurement resistance values of the direct current voltage-sharing resistor at different sampling moments are obtained through ohm's law, the average value of the first measurement resistance values is obtained, the first measurement resistance values are compared with the known resistance values of the direct current voltage-sharing resistor, and a first running state is obtained.
Uj＝Um-K·Uk (3)
Wherein U ismThe four sampling moments are used for calculating the end voltage of the thyristor.
2. Diagnosis of the operating state of the damping resistor, i.e. the second operating state:
the damping resistor adopts the same monitoring method as the direct current voltage-sharing resistor to measure the voltage and the current at two ends of the resistor, and then the resistance value is calculated according to the ohm law. The current flowing through the damping loop in a steady state is very small, and measurement is inconvenient, so that the damping resistance is measured in a transient process after the thyristor is triggered and conducted. After the thyristor is conducted, a second sampling current flowing through the damping resistor is sampled through a second current sampling resistor, the voltage of the high potential end of the damping resistor to the ground and the voltage of the low potential end of the damping resistor to the ground are respectively sampled through a resistance-capacitance voltage divider, and then a second measurement resistance value of the damping resistor is calculated through a second voltage and the second sampling current at a second sampling moment.
A specific embodiment of the damping resistance measuring circuit is shown in FIG. 5, in order to obtain the current I on each damping resistanceRA second sampling resistor R is connected in series between each damping resistor and the thyristor trigger detection devices1And Rs2Resistance Rs1And Rs2The resistance value of the damping resistor is very small, the influence on the current flowing on the damping resistor can be ignored,
in order to obtain the voltage of the low potential end of the damping resistor, a resistance-capacitance voltage divider is connected between each damping resistor and the second sampling resistor, namely voltages Us1 and Us2 are obtained, in order to obtain the voltage to ground of the high potential end of the damping resistor, a resistance-capacitance voltage divider is connected to the connection point of the damping capacitor and the damping resistor, and like a measuring circuit of a direct current equalizing resistor, the resistance-capacitance voltage divider is formed by connecting a series of resistor capacitors in series-parallel, R is a resistor, and the voltage to ground of the high potential end of the damping resistor is a voltage divider connected to the connection point of the damping capacitor and the damping resistor in series-parallela、Rb、CaAnd CbThe relationship of (c) also satisfies:
and K is the voltage division ratio of the resistance-capacitance voltage divider.
Wherein the RC voltage divider can pass through the voltage UkThe product of the voltage division ratio and the obtained damping resistance is highThe potential end is connected to the ground voltage, and a second voltage on the damping resistor and a second damping measurement resistance value obtained by a schematic diagram are as follows:
comparing the second measured resistance value with the known resistance value of the damping resistor to obtain a second running state of the damping resistor
3. Diagnosis of the state of the damping capacitance impedance, i.e. the third operating state:
the conventional direct capacitance measurement method can only measure capacitance values of capacitors in an off-line condition, such as an ac bridge. In order to meet the requirement of on-line monitoring of the extra-high voltage direct current transmission converter valve, the invention designs a circuit for realizing capacitance monitoring according to a method for indirectly measuring capacitance value of a capacitor through the instant process of capacitor discharging under the condition that the capacitor is electrified, and the circuit diagram is the same as a measuring circuit diagram of a damping resistor, and is shown in figure 5.
When the thyristor is conducted, the damping capacitor discharges to the damping resistor through the thyristor, and the capacitance value of the damping capacitor can be calculated as long as the discharge current and the voltage change rate of the damping capacitor are known,
the circuit design of fig. 5 can directly measure not only the third sampling current discharged by the damping capacitor, but also the third sampling voltage of the damping capacitor. Discharging third current I of damping capacitorcThe sum of the currents of the two damping branches is obtained; after the thyristor is conducted, the voltage drop at two ends is zero, and the third voltage U on the damping capacitorcNamely the inverse voltage of the resistance-capacitance voltage divider, four voltage, current and time values are obtained through four times of sampling, the variation of the three voltage, current and time can be calculated according to the formula (1)2) And calculating the capacitance values of the three damping capacitors, and then averaging to obtain the measurement result of the impedance of the damping capacitor.
Ic＝IRx+IRd (10)
Uc＝-K·Uk (11)
And comparing the impedance value of the damping capacitor with the known impedance value of the damping capacitor to obtain a third running state of the damping capacitor.
4. Damping circuit state, i.e. fourth operating state diagnosis:
the resistance-capacitance integral monitoring does not measure the actual value of each component of the damping loop independently, but measures and calculates the damping resistance and the damping capacitance as a whole. When the thyristor is conducted, the damping capacitor discharges to the damping resistor through the thyristor, the circuit can be equivalent to a zero input response of the first-order RC circuit, the discharge time is fixed and unchanged when the parameters of the damping circuit components are normal according to the general formula of the zero input response of the first-order RC circuit, and the discharge time can be changed when the resistance value of the damping resistor or the capacitance value of the damping capacitor changes. As shown in FIG. 6, the time taken for the discharge current of the damping capacitor to decrease from the peak value to 50% of the peak value is t, and when t is less than tmaxGreater than tminAnd if not, the damping circuit is considered to be abnormal. The method for monitoring the whole resistance-capacitance is to judge whether the time required by the current of the damping resistance branch circuit to drop from the peak value to half of the peak value at the moment of switching on the thyristor is changed.
The resistance-capacitance integral monitoring principle is shown in FIG. 7, in which the damping resistor RxThe branch is connected in series with a small resistor RsMeasuring the resistance R by means of a RC voltage dividersVoltage of (2), namely obtaining the damping resistance RxThe current of the branch.
According to formula (13)
The time required for the damping capacitor discharge circuit current to drop from peak to half of the peak is t- τ · ln 0.5, i.e., t ═ τ · ln
The detection principle of the discharge current falling time of the damping capacitor is shown in FIG. 8, and the input signal of the circuit is the resistor R shown in FIG. 7sVoltage signal U ofsThe output is a resistance RsEdge signals falling to half the peak. Due to UsNegative values, the capacitor C cannot be charged, so a one-stage inverting amplifier is required. In the process of the output voltage rise of the amplifier, the capacitor C is charged through the diode D, when the input voltage reaches the peak value, the voltage on the capacitor C is the peak value of the input voltage, after the voltage is divided by the two resistors R with the same resistance value, half of the peak voltage is obtained, and the peak voltage is sent to the comparator. When the input voltage begins to drop, the capacitor can only discharge to the resistor R due to the existence of the diode D, the discharge time is longer when the resistance value of the resistor R is larger, and the voltage after voltage division can be considered to be kept unchanged in a short time. When the input voltage is reduced to less than half of the peak value, the output level of the comparator jumps, and the edge signal is the moment when the discharge current of the damping capacitor is reduced to half of the peak value.
The charging time of the damping capacitor at the moment of the thyristor conduction is very short and can be ignored, so that a thyristor trigger signal is taken as a signal for starting timing, an edge signal output by the comparator in fig. 8 is a signal for stopping timing, a time interval is the time spent by the damping capacitor for discharging current to be reduced from a peak value to a half of the peak value, the fourth running state of the whole damping circuit can be obtained by comparing the time with the time of the formula (14), and when a monitoring value exceeds an upper limit threshold value and a lower limit threshold value, an alarm is sent out to prompt that the whole damping circuit has fault hidden danger.
The embodiment of the invention also provides a system for diagnosing the fault of the thyristor-level loop of the direct-current transmission converter valve, which comprises the following steps: the method comprises a current sampling circuit, a voltage sampling circuit, a time detection circuit, a memory and a processor, wherein the current sampling circuit, the voltage sampling circuit, the time detection circuit, the memory and the processor are connected in a communication mode, computer instructions are stored in the memory, and the processor executes the computer instructions so as to execute the method for diagnosing the fault of the thyristor-level loop of the direct-current power transmission converter valve according to the claims 1 to 4 or 5 to 7. The current sampling circuit can be a resistor with a small resistance value and is used for being connected in each loop in series to collect current in each loop. The voltage sampling circuit can comprise a resistance-capacitance voltage divider and can acquire the voltage at any position. The time detection circuit may detect a time period required for the impedance loop capacitance to discharge to half of the peak value from the start of discharge. See in particular the circuit shown in fig. 8. The processor 51 and the memory 52 may be connected by a bus or other means.
The processor may be a Central Processing Unit (CPU). The Processor 51 may also be other general purpose processors, Digital Signal Processors (DSPs), Application Specific Integrated Circuits (ASICs), Field Programmable Gate Arrays (FPGAs) or other Programmable logic devices, discrete Gate or transistor logic devices, discrete hardware components, or combinations thereof.
The memory, which is a non-transitory computer readable storage medium, may be used to store non-transitory software programs, non-transitory computer executable programs, and modules, such as program instructions/modules corresponding to the fault detection methods in the embodiments of the present invention. The processor executes various functional applications and data processing of the processor by executing non-transitory software programs, instructions and modules stored in the memory, that is, the fault detection method in the above method embodiment is implemented.
The memory may include a storage program area and a storage data area, wherein the storage program area may store an operating system, an application program required for at least one function; the storage data area may store data created by the processor, and the like. Further, the memory may include high speed random access memory, and may also include non-transitory memory, such as at least one disk storage device, flash memory device, or other non-transitory solid state storage device. In some embodiments, the memory optionally includes memory located remotely from the processor, and such remote memory may be coupled to the processor via a network. Examples of such networks include, but are not limited to, the internet, intranets, local area networks, mobile communication networks, and combinations thereof.
One or more modules are stored in the memory and, when executed by the processor, perform the fault detection method in the embodiment shown in fig. 2 or 3.
It will be understood by those skilled in the art that all or part of the processes of the methods of the embodiments described above can be implemented by hardware related to instructions of a computer program, and the program can be stored in a computer readable storage medium, and when executed, can include the processes of the embodiments of the methods described above. The storage medium may be a magnetic Disk, an optical Disk, a Read-Only Memory (ROM), a Random Access Memory (RAM), a Flash Memory (Flash Memory), a Hard Disk (Hard Disk Drive, abbreviated as HDD) or a Solid State Drive (SSD), etc.; the storage medium may also comprise a combination of memories of the kind described above.
Although the embodiments of the present invention have been described in conjunction with the accompanying drawings, those skilled in the art may make various modifications and variations without departing from the spirit and scope of the invention, and such modifications and variations fall within the scope defined by the appended claims.
Claims (10)
1. The fault diagnosis method for the thyristor-level loop of the direct-current transmission converter valve is characterized in that the thyristor-level loop comprises a thyristor, a thyristor trigger monitoring device, a voltage-sharing loop and a damping loop, and the damping loop comprises a damping resistor and a damping capacitor;
obtaining a first running state of the voltage-sharing loop according to a first sampling current of the voltage-sharing loop in the turn-off state of the thyristor and a first voltage at two ends of the voltage-sharing loop at a first sampling moment, wherein the first sampling moment is any moment between a positive zero crossing point and a turn-on moment of the voltage at two ends of the thyristor;
obtaining a second running state of the damping resistor according to a second sampling current of the damping resistor and a second voltage at two ends of the damping resistor at a second sampling moment, wherein the second sampling moment is any moment of a transient process after the thyristor is triggered and conducted;
obtaining a third running state of the damping capacitor according to a third sampling current discharged by the damping capacitor and third voltages at two ends of the damping capacitor at least two third sampling moments, wherein the third sampling moments are thyristor conduction moments;
and determining the operation state of the thyristor-level loop of the direct-current transmission converter valve based on the first operation state, the second operation state and the third operation state.
2. The method for diagnosing the fault of the thyristor-level circuit of the direct-current transmission converter valve according to claim 1, wherein the voltage-sharing circuit comprises a direct-current voltage-sharing resistor, the first sampling current is obtained by sampling through a first sampling resistor, and the first sampling resistor is connected in series between a low-potential end of the direct-current voltage-sharing resistor and a thyristor triggering monitoring device;
the obtaining of the first running state of the voltage-sharing circuit according to the first sampling current of the voltage-sharing circuit in the off state of the thyristor and the first voltage at two ends of the voltage-sharing circuit at the first sampling moment comprises:
acquiring the voltage of the low potential end of the direct current voltage-sharing resistor at the first sampling moment;
obtaining the first sampling current according to the voltage of the low potential end to the ground of the direct current voltage-sharing resistor and the first sampling resistor;
obtaining the voltage of the high potential end of the direct current equalizing resistor at the first sampling moment according to the voltage peak values at the two ends of the thyristor and the first sampling moment;
obtaining a first measurement resistance value of the direct current voltage-sharing resistor according to the first sampling current, the voltage to ground of the high potential end of the direct current voltage-sharing resistor and the voltage to ground of the low potential end of the direct current voltage-sharing resistor;
and comparing the first measured resistance value with a first preset resistance value to obtain the first running state.
3. The method for diagnosing the fault of the thyristor-level loop of the direct-current transmission converter valve according to claim 1, wherein the step of obtaining the second operation state of the damping resistor according to the second sampling current of the damping resistor and the second voltage across the damping resistor at the sampling moment comprises the steps of:
respectively acquiring the low-potential voltage-to-ground voltage and the high-potential voltage-to-ground voltage of the damping resistor at the second sampling moment;
obtaining a second sampling current according to the low-potential voltage-to-ground voltage of the damping resistor and a second sampling resistor, wherein the second sampling resistor is connected in series between the damping resistor and the thyristor trigger monitoring device;
obtaining a second measurement resistance value of the damping resistor according to the second sampling current, the voltage to ground of the high-potential end of the damping resistor and the voltage to ground of the low-potential end of the damping resistor;
and comparing the second measured resistance value with a second preset resistance value to obtain the second running state.
4. The method according to claim 1, wherein obtaining the third operating state of the damping capacitor according to the third sampling current discharged by the damping capacitor and the third voltages across the damping capacitor at least two third sampling moments comprises:
respectively acquiring the low-potential voltage-to-ground voltage and the high-potential voltage-to-ground voltage of the damping resistor at the third sampling moment;
obtaining a third sampling current according to the low-potential voltage-to-ground voltage of the damping resistor and a third sampling resistor, wherein the third sampling resistor is connected in series between the damping resistor and the thyristor trigger monitoring device;
obtaining an impedance value of the damping capacitor according to the third sampling current and the voltage of the damping resistor high-potential end to ground;
and comparing the impedance value of the damping capacitor with a preset impedance value to obtain the third running state.
5. A fault diagnosis method for a thyristor-level loop of a direct-current transmission converter valve is characterized in that the thyristor-level loop comprises a thyristor, a thyristor trigger monitoring device, a voltage-sharing loop and a damping loop, and the fault diagnosis method comprises the following steps:
obtaining a first running state of the voltage-sharing loop according to a first sampling current of the voltage-sharing loop in the turn-off state of the thyristor and a first voltage at two ends of the voltage-sharing loop at a first sampling moment, wherein the first sampling moment is any moment between a positive zero crossing point and a turn-on moment of the voltage at two ends of the thyristor;
obtaining a fourth running state of the damping loop according to the discharging time required by the discharging current in the damping loop to be reduced from the peak value to half of the peak value when the thyristor is in the on state;
determining an operating state of the thyristor-level loop of the direct-current transmission converter valve based on the first operating state and the fourth operating state;
the damping circuit is connected with a time detection circuit, the time detection circuit is used for outputting level jump when the discharging current of the damping circuit is reduced to half of the peak value, and the time detection circuit is composed of a primary reverse amplifier, a diode, a capacitor and two divider resistors.
6. The method for diagnosing the fault of the thyristor-level circuit of the direct-current transmission converter valve according to claim 5, wherein the voltage-sharing circuit comprises a direct-current voltage-sharing resistor, the first sampling current is obtained by sampling through a first sampling resistor, and the first sampling resistor is connected in series between a low-potential end of the direct-current voltage-sharing resistor and the thyristor triggering monitoring device;
the obtaining of the first running state of the voltage-sharing circuit according to the first sampling current of the voltage-sharing circuit in the off state of the thyristor and the first voltage at two ends of the voltage-sharing circuit at the first sampling moment comprises:
acquiring the voltage of the low potential end of the direct current voltage-sharing resistor at the first sampling moment;
obtaining the first sampling current according to the voltage of the low potential end to the ground of the direct current voltage-sharing resistor and the first sampling resistor;
obtaining the voltage of the high potential end of the direct current equalizing resistor at the first sampling moment according to the voltage peak values at the two ends of the thyristor and the first sampling moment;
obtaining a first measurement resistance value of the direct current voltage-sharing resistor according to the first sampling current, the voltage to ground of the high potential end of the direct current voltage-sharing resistor and the voltage to ground of the low potential end of the direct current voltage-sharing resistor;
and comparing the first measured resistance value with a first preset resistance value to obtain the first running state.
7. The method according to claim 5, wherein the discharge current is obtained through a fourth sampling resistor, and the fourth sampling resistor is connected in series between a damping resistor and the thyristor trigger monitoring device;
the obtaining of the fourth operating state of the damping loop according to the discharge duration required by the discharge current in the damping loop to decrease from the peak value to half of the peak value in the thyristor on state includes:
recording a time interval from the thyristor being turned on to the output level of the time detection circuit jumping, wherein the time interval is the discharge duration;
and comparing the discharge time length value with a preset time length to obtain the fourth running state.
8. The utility model provides a direct current transmission converter valve thyristor level return circuit fault diagnosis device, thyristor level return circuit includes thyristor, thyristor trigger monitoring devices, voltage-sharing return circuit, damping return circuit, its characterized in that includes:
the first state detection module is used for obtaining a first running state of the voltage-sharing loop according to a first sampling current of the voltage-sharing loop in the turn-off state of the thyristor and a first voltage at two ends of the voltage-sharing loop at a first sampling moment, wherein the first sampling moment is any moment between a positive zero crossing point and a turn-on moment of the voltage at two ends of the thyristor;
the second state detection module is used for obtaining a second running state of the damping resistor according to a second sampling current of the damping resistor and a second voltage at two ends of the damping resistor at a second sampling moment, wherein the second sampling moment is any moment of a transient process after the thyristor is triggered and conducted;
the third state detection module is used for obtaining a third running state of the damping capacitor according to a third sampling current discharged by the damping capacitor and third voltages at two ends of the damping capacitor at least two third sampling moments, wherein the third sampling moments are thyristor conduction moments;
a first diagnostic module configured to determine an operating state of the thyristor-level circuit of the dc transmission converter valve based on the first operating state, the second operating state, and the third operating state.
9. The utility model provides a direct current transmission converter valve thyristor level return circuit fault diagnosis device, thyristor level return circuit includes thyristor, thyristor trigger monitoring devices, voltage-sharing return circuit, damping return circuit, its characterized in that includes:
the first state detection module is used for obtaining a first running state of the voltage-sharing loop according to a first sampling current of the voltage-sharing loop in the turn-off state of the thyristor and a first voltage at two ends of the voltage-sharing loop at a first sampling moment, wherein the first sampling moment is any moment between a positive zero crossing point and a turn-on moment of the voltage at two ends of the thyristor;
the fourth state detection module is used for obtaining a fourth running state of the damping loop according to the discharging time required by the discharging current in the damping loop to be reduced from the peak value to half of the peak value when the thyristor is in the on state;
the second diagnosis module is used for determining the operation state of the thyristor-level loop of the direct-current transmission converter valve based on the first operation state and the fourth operation state;
the damping circuit is connected with a time detection circuit, the time detection circuit is used for outputting level jump when the discharging current of the damping circuit is reduced to half of the peak value, and the time detection circuit is composed of a primary reverse amplifier, a diode, a capacitor and two divider resistors.
10. A direct current transmission converter valve thyristor level loop fault diagnosis system is used for diagnosing faults of the direct current transmission converter valve thyristor level loop, and is characterized by comprising the following steps:
the method comprises a current sampling circuit, a voltage sampling circuit, a time detection circuit, a memory and a processor, wherein the current sampling circuit, the voltage sampling circuit, the time detection circuit, the memory and the processor are connected in communication with each other, the memory stores computer instructions, and the processor executes the computer instructions so as to execute the method for diagnosing the thyristor-level loop fault of the direct current transmission converter valve according to any one of claims 1 to 4 or 5 to 7.
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| CN112684737A (en) * | 2020-12-11 | 2021-04-20 | 郑州大学 | Suspension potential on-line monitoring system with voltage-sharing function |
| CN113514749A (en) * | 2021-07-07 | 2021-10-19 | 中国南方电网有限责任公司超高压输电公司贵阳局 | Thyristor voltage-sharing detection device and detection method |
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| CN102158060B (en) * | 2011-03-02 | 2014-12-03 | 中国电力科学研究院 | Novel direct-current converter valve thyristor damping loop |
| CN106646007B (en) * | 2015-10-29 | 2019-05-21 | 国网智能电网研究院 | A kind of HVDC thyristor grade damping circuit dynamic parameter on-line monitoring method |
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