CN102901925B - Super, extra-high voltage direct-current isolating switch conversing circuits characterisitic parameter method of testing - Google Patents

Abstract

The invention discloses a method for testing the characteristic parameters of a conversion circuit of an ultra-high voltage DC circuit breaker, which relates to a method for testing the characteristic parameters of the conversion circuit of a passive type and an active type oscillation circuit of the ultra-high voltage DC circuit breaker. According to the different charging voltages (passive type) or different charging times (active type) of the switching capacitor bank, the switching circuit current I waveform collected by operating the circuit breaker, the frequency f and the decay time constant τ of the switching circuit are respectively obtained. Finally, the characteristic parameters of the conversion circuit in a certain range are obtained. The inductance of the converter loop reactor (there is a converter loop without a reactor), the sum of the capacitor inductance and the line inductance constitutes the converter loop inductance: ; The damping resistance of the conversion circuit is .

Description

Test method for characteristic parameters of conversion circuit of ultra-high voltage and ultra-high voltage DC circuit breakers

technical field

The invention relates to a method for testing characteristic parameters of a high-voltage direct current circuit breaker in an electric power system, in particular to a method for testing characteristic parameters of a conversion circuit of an ultra-high voltage and ultra-high voltage direct current circuit breaker.

Background technique

The high-voltage DC circuit breaker for the DC field of the converter station of the ultra-high voltage DC transmission project is an important equipment for the DC field of the converter station, mainly including the neutral bus switch (NBS), the metal return switch (MRTB), and the earth return switch ( GRTS) and so on. They function as transfer switches and are mainly used for the conversion of various operating modes of the DC transmission system, such as grounding system conversion, fault handling, etc. Since the DC current has no natural zero-crossing point, the arc in the fracture is not easy to extinguish, so the AC circuit breaker cannot be directly used to break the DC current. A high-voltage DC circuit breaker composed of an AC circuit breaker and a conversion circuit must be used to effectively break the DC current. Especially in ultra-high voltage and ultra-high voltage DC systems, it is very important to realize the reliable and effective breaking of DC current. In recent years, high-voltage direct current transmission technology has developed rapidly in my country, and has become the development direction of long-distance transmission of electric energy. Oscillating circuit characteristic parameter test.

The high-voltage DC circuit breaker is actually composed of an AC circuit breaker and a conversion circuit (LC self-excited oscillation circuit, arrester group (absorbing energy during conversion)) in parallel. The LC self-excited oscillation circuit is divided into passive type and active type. The principle of breaking DC current is the same. DC breaking is to use the nonlinear negative resistance characteristic that the arc voltage decreases with the increase of current, and then generate self-excited oscillation in the LC loop connected in parallel with the arc gap, so that the arc current is superimposed on the amplitude oscillation current, and it is realized when the total current crosses zero. break. Therefore, it is required that the parameters of the AC circuit breaker and the conversion circuit (LC self-excited oscillation) have better cooperation.

Since the EHV and UHV DC transmission technologies have not been used in my country for a relatively long time, there are no clear requirements for the project in the handover and acceptance items of the converter stations of the EHV and UHV DC transmission projects in the power system, and there is no regulation for high voltage Test method for characteristic parameters of DC circuit breaker conversion circuit.

Contents of the invention

The purpose of the present invention is to provide a method for testing the characteristic parameters of the conversion circuit of the passive type and active type oscillation circuit of the ultra-high voltage and ultra-high voltage DC circuit breakers with accurate and reliable test results.

The object of the present invention is achieved in this way: a method for testing the characteristic parameters of the conversion circuit of the ultra-high voltage DC circuit breaker, comprising: the high voltage DC circuit breaker is composed as follows: the conversion capacitor bank is connected in series with the reactor H and connected in parallel with the lightning arrester BL In the conversion circuit, the high-voltage AC circuit breaker CB is connected in parallel with the arrester group BL; the characteristic is that it is carried out according to the following steps:

1) When the high-voltage AC circuit breaker is in the closed state, after safely grounding the conversion capacitor bank, untie the drain wire terminal connecting the high-voltage AC circuit breaker to the reactor H, and pass the untwisted drain wire through the Roche After the coil CT, restore and fasten the terminal, and then connect the signal output end of the Rogowski coil CT to the oscilloscope;

2) The test method for the characteristic parameters of the passive conversion circuit is as follows:

Use an external DC charging power supply U, the positive and negative poles of the power supply U are connected to both ends of the conversion capacitor bank through the charging switch SW1, and are ready to charge the conversion capacitor bank; when the high-voltage AC circuit breaker CB is closed, the external DC charging is performed The wiring of the power supply U, after the wiring is completed, operate the high-voltage AC circuit breaker to open;

Monitor the charging voltage through the voltmeter V of the DC charging power supply U, and charge the conversion capacitor bank to 200V, 400V, 500V, 600V, 800V and 1000V respectively; under the above-mentioned different stable charging voltage values of the conversion capacitor bank, turn off the charging switch SW1 , so that the DC charging power supply U is separated from the conversion capacitor bank;

Under the above-mentioned different charging voltages of the conversion capacitor bank, the high-voltage AC circuit breaker is operated to close, so that the conversion circuit undergoes self-excited oscillation, and the self-excited oscillation current waveform is collected by an oscilloscope, thereby obtaining the conversion circuit frequency f, conversion circuit inductance L, Conversion circuit damping resistance R and conversion circuit current I;

The conversion loop inductance is the sum of reactor inductance, capacitor inductance and line inductance;

3) The test method for the characteristic parameters of the active conversion circuit is as follows:

The charging device E is connected in parallel with the conversion capacitor bank, and the unipolar switch S is connected in series between the conversion capacitor bank and the reactor H;

When testing the characteristic parameters of the active conversion circuit, manually disconnect the single-pole switch S, and let the charging device E charge the conversion capacitor bank for 1s, 5s, 10s, 30s, and 60s respectively. After each charging is completed, Manually close the single-pole switch S, then close the high-voltage AC circuit breaker, and collect the self-excited oscillation current waveform through the oscilloscope, so as to obtain the conversion circuit frequency f, conversion circuit inductance L, conversion circuit damping resistance R and conversion circuit current I;

4) Carry out the characteristic parameter calculation of conversion circuit:

For the above passive and active conversion circuits, directly measure the capacitance C of the conversion capacitor bank;

According to the conversion circuit current waveform collected by the conversion capacitor bank with different charging voltages under the passive type condition or the different charging time under the above active type condition, the frequency f and the decay time constant τ of the conversion circuit are respectively obtained, then finally Obtain the characteristic parameters of the conversion circuit in a certain range;

The conversion loop inductance L is:

$\mathrm{<span\; class="notranslate">\; L</span>}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; \&pi;f</span>}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; \&Center\; Dot;</span>\mathrm{<span\; class="notranslate">\; C</span>}}$

The conversion loop inductance L is the sum of the reactor inductance, capacitor inductance and line inductance;

The damping resistance R of the conversion circuit is:

$\mathrm{<span\; class="notranslate">\; R</span>}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; L</span>}}{\mathrm{<span\; class="notranslate">\; \&tau;</span>}}$

The test method is characterized in that when testing the characteristic parameters of the active conversion circuit, the external DC charging power supply U is also connected in parallel with a monitoring voltmeter V.

The oscilloscope model is Tektronix DPO3012, the Rogowski coil model is CL-2000, and the external DC charging power supply model is SCDC1000/10.

The invention has the beneficial effects that: the high-voltage direct current circuit breaker is an important device of the direct current field of the converter station of the ultra-high voltage direct current transmission project, and plays the role of a transfer switch. When the EHV and UHV converter stations switch between different operation modes of earth return or metal return, it is necessary to break and transfer thousands of amperes of DC current. Although the high-voltage AC circuit breaker has a strong ability to break short-circuit current, Because the DC current does not have a zero crossing point like the AC current, it is difficult to extinguish the arc and cut off the current at the fracture of the circuit breaker. In order to enhance the ability of DC arc extinguishing and current interruption, a conversion circuit is connected in parallel between the breakers of the AC circuit breaker to create a zero-crossing point of the current so that the AC circuit breaker can break the DC current. In order to ensure that the DC circuit breaker can reliably break the DC current, the characteristic parameters such as the frequency and damping resistance of the conversion circuit must be measured on site to ensure that it meets the design and use requirements, and ensure the safety and reliability of the converter station of the EHVDC transmission project. to operate in different ways during conversion.

UHV can greatly enhance the transmission capacity of my country's power grid. According to the data provided by the State Grid Corporation of China, the UHV DC power grid of the primary circuit can transmit 6 million kilowatts of electricity, which is equivalent to 5 to 6 times that of the existing 500 kV DC power grid, and the power transmission distance is also 2 to 3 times that of the latter. Therefore, the efficiency is greatly improved. In addition, according to the calculations of the State Grid Corporation of China, if the power transmission of the same power is carried out, the use of UHV lines can save 60% of land resources compared with the use of 500 kV EHV lines. The national "Twelfth Five-Year Plan" mentioned in the national "Twelfth Five-Year Plan" that to meet the requirements of large-scale cross-regional power transmission and new energy power generation grid integration, speed up the construction of a modern power grid system, further expand the scale of west-to-east power transmission, improve regional backbone power grids, and develop super and special power grids. High-voltage and other large-capacity, high-efficiency, and long-distance advanced transmission technologies. As a hydropower province rich in clean energy, the future development of Sichuan will depend on the construction of UHV power grids. Therefore, this invention is also based on better serving ultra-high voltage and UHV power transmission. engineering purpose.

The method and device adopt the current sensor CT of the Rogowski coil, which avoids the problem of changing the characteristic parameters of the conversion circuit caused by the access current testing device such as the shunt, the saturation defect of the electromagnetic current transformer, and the temperature drift and precision response of the Hall sensor. Disadvantages of narrow range and constant need for calibration. The method and device have been successfully applied by the inventors to the on-site handover test of the HVDC circuit breaker in the "Jinping-Sunan UHVDC Transmission Project ±800kV Yulong Converter Station".

Description of drawings

Fig. 1 is a circuit schematic diagram of the conversion circuit of the passive high-voltage DC circuit breaker of the present invention (the conversion circuit is inside the dotted line frame).

Fig. 2 is a circuit schematic diagram of the conversion circuit of the active DC circuit breaker of the present invention.

Fig. 3 is a schematic diagram of a circuit (passive type) in which the conversion circuit shown in Fig. 1 is externally connected to a DC charging power supply.

Fig. 4 is an oscillation waveform diagram of the actual test of the ±800kV Yulong converter station of the present invention.

Detailed ways

1) Referring to Figure 3, when the circuit breaker under test is in the closed state, after safely grounding the conversion capacitor bank C, untie the terminal of the drain wire connecting the circuit breaker under test to the conversion circuit platform, and pass the untied drain wire through After the Rogowski coil CT, restore and tighten the terminal. That is, the connection line from the circuit breaker to the conversion circuit platform passes through the Rogowski coil CT.

The current sensor CT using the Rogowski coil avoids the problem of changing the characteristic parameters of the conversion circuit caused by the access current test device such as the shunt, the saturation defect of the electromagnetic current transformer, the temperature drift of the Hall sensor, the narrow precision response range and the time Disadvantage of requiring calibration.

2) Test the characteristic parameters of the passive conversion circuit, see Figure 3.

An external DC charging power supply U is used, and its positive and negative poles are connected to both ends of the conversion capacitor bank C through the charging switch SW1, and the conversion capacitor bank C is ready to be charged. When the circuit breaker CB under test is closed, connect the external DC charging power supply U, and after the wiring is completed, open the circuit breaker under test.

The charging voltage is monitored by the voltmeter V of the DC charging power supply U, and the switching capacitor bank C is charged to 200V, 400V, 500V, 600V, 800V and 1000V respectively. Under the different charging voltage stable values of the switching capacitor bank C, the charging switch SW1 is turned off, so that the DC charging power supply E is separated from the switching capacitor bank C.

Under the different charging voltages of the switching capacitor bank C, the circuit breaker CB under test is operated to close, that is, the dynamic and static contacts of the main fracture are closed, and the switching capacitor bank and the switching loop inductance make the switching loop self-excited oscillation, through the waveform acquisition device (such as a digital storage oscilloscope) to collect the self-excited oscillation current waveform (see Figure 4), so as to obtain the conversion circuit frequency f, conversion circuit inductance L, conversion circuit damping resistance R and conversion circuit current I.

The inductance of the conversion loop is the sum of the inductance of the reactor (there is a conversion loop without a reactor), the inductance of the capacitor and the inductance of the line.

3) Test the characteristic parameters of the active conversion circuit, see Figure 2.

Compared with the passive type, it has a charging device and a single-pole switch S (see Figure 2). During normal operation, the unipolar switch S is disconnected, and the charging device E charges the conversion capacitor bank. The loop inductance self-oscillates.

When testing the characteristic parameters of the conversion circuit, let the charging device E charge the conversion capacitor bank C for different times. After the charging is completed, manually close the single-pole switch S, and then close the circuit breaker under test, that is, its main break The dynamic and static contacts are closed, and the self-excited oscillation current waveform is collected by a waveform acquisition device (such as a digital storage oscilloscope), so as to obtain the conversion circuit frequency f, conversion circuit inductance L, conversion circuit damping resistance R and conversion circuit current I.

When testing the characteristic parameters of the conversion circuit, the charging device assists the control circuit, allowing the charging device E to charge the conversion capacitor bank for 1s, 5s, 10s, 30s, 60s, etc. The pole switch S is closed, then the circuit breaker under test is closed, the dynamic and static contacts of the main fracture CB are closed, and the waveform acquisition device (such as a digital storage oscilloscope) is used to collect the self-excited oscillation current waveform, so as to obtain the conversion circuit frequency f and the conversion circuit inductance L, conversion circuit damping resistance R and conversion circuit current I.

4) Calculate the characteristic parameters of the conversion circuit.

Regardless of the passive and active conversion circuits, the capacitance value C of the capacitor bank of the conversion circuit can be directly measured.

According to the conversion circuit current I waveform collected by different charging voltages (passive type) or different charging time (active type) of the conversion capacitor bank, the frequency f and decay time constant τ of the conversion circuit are obtained respectively. Finally, the characteristic parameters of the conversion circuit in a certain range are obtained.

The sum of the inductance of the converter loop reactor (there is a converter loop without a reactor), the inductance of the converter capacitor and the line inductance is

$\mathrm{<span\; class="notranslate">\; L</span>}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; \&pi;f</span>}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; \&Center\; Dot;</span>\mathrm{<span\; class="notranslate">\; C</span>}}$

The damping resistance of the conversion circuit is

$\mathrm{<span\; class="notranslate">\; R</span>}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; L</span>}}{\mathrm{<span\; class="notranslate">\; \&tau;</span>}}$

5) Example of test and calculation of characteristic parameters of conversion circuit.

After measuring the conversion circuit conversion capacitor bank capacitance C = 60μF;

From Figure 4, it can be obtained that the time for five oscillation cycles of the switching current is 984μs;

Therefore, the conversion circuit oscillation frequency f = 5081Hz;

Attenuation time constant τ=0.684ms;

The switching loop oscillation inductance consists of Calculated, 16μH;

The damping resistance of the conversion loop is determined by Calculated, 46mΩ.

The main functions and technical indicators of this device:

Main functions: Provide a method for testing the characteristic parameters of the conversion circuit of the passive and active oscillation circuits of ultra-high voltage and ultra-high voltage DC circuit breakers. Thus, the frequency f of the conversion circuit, the inductance L of the conversion circuit, the damping resistance R of the conversion circuit and the current I of the conversion circuit are obtained.

Technical indicators of the test device for the characteristic parameters of the conversion circuit of the ultra-high voltage DC circuit breaker:

DC charging power supply voltage: 0 ~ 1000V;

DC charging power supply current: 0～10A;

DC charging power output accuracy: 0.1%;

Temperature drift of DC charging power supply: 0.05%/℃;

Drift when DC charging power supply: 0.05%/h;

Waveform acquisition device (oscilloscope): 100MHz/2.5GS/s;

Current sensor (Rogowski coil): 2000A

Current sensor sensing coefficient: 0.059.

The parameters of the main equipment of the device:

Oscilloscope CRT: Model Tektronix DPO3012;

Current sensor (Rogowski coil): model CL-2000

Digital multimeter: Model FLUKE8845A;

DC charging power supply (connected by switch SW1 in Figure 3): model SCDC1000/10.

Claims (3)

1. super, an extra-high voltage direct-current isolating switch conversing circuits characterisitic parameter method of testing, comprise, high voltage DC breaker is composed as follows: in parallel with lightning arrester BL and form conversing circuits after changeover condenser group tandem reactor H, high-voltage AC breaker CB is in parallel with lightning arrester group BL; It is characterized in that, carry out according to the following steps:

1) when described high-voltage AC breaker "on" position, after safety ground is carried out to changeover condenser group, untie the drainage thread terminal that high-voltage AC breaker connects described reactor H, after the drainage thread untied is passed Luo-coil CT, recover and this terminal fastening, then the signal output part of Luo-coil CT is connected to oscillograph;

2) as follows to the characterisitic parameter method of testing of passive conversing circuits:

Adopt external DC charging power supply U, the positive and negative electrode of this power supply U is connected to changeover condenser group two ends after charge switch SW1, prepares and charges to changeover condenser group; When high-voltage AC breaker CB "on" position, carry out the wiring of external DC charging power supply U, after wiring completes, operate high pressure AC circuit breaker separating brake;

Monitor charging voltage by the voltage table V of DC charging power supply U, respectively 200V, 400V, 500V, 600V, 800V and 1000V are charged to changeover condenser group; Under the above-mentioned different charging voltage stationary values of changeover condenser group, turn off charge switch SW1, makes DC charging power supply U depart from changeover condenser group;

Respectively under the above-mentioned different charging voltage of changeover condenser group, operate high pressure AC circuit breaker closes a floodgate, make conversing circuits generation self-sustained oscillation, gather self-sustained oscillation current waveform by oscillograph, thus obtain conversing circuits frequency f, conversing circuits inductance L, conversing circuits damping resistance R and conversing circuits electric current I;

Conversing circuits inductance is reactor inductance, capacitor inductance and line inductance sum;

3) as follows to the characterisitic parameter method of testing of active type conversing circuits:

Charging device E is in parallel with changeover condenser group, and single-pole switch S is serially connected between changeover condenser group and reactor H;

When the characterisitic parameter of active type conversing circuits is tested, artificial disconnection single-pole switch S, charging device E is allowed changeover condenser group to be carried out respectively to the charging of 1s, 5s, 10s, 30s, 60s time, after each charging complete, single-pole switch S is manually made to close respectively, make high-voltage AC breaker close a floodgate again, gather self-sustained oscillation current waveform by oscillograph, thus obtain conversing circuits frequency f, conversing circuits inductance l, conversing circuits damping resistance rand conversing circuits electric current i;

4) characterisitic parameter carrying out conversing circuits calculates:

To above-mentioned passive and active type conversing circuits, directly measure the capacitance obtaining changeover condenser group c;

According to the conversing circuits current waveform that the above-mentioned different charging voltage under passive condition of changeover condenser group or above-mentioned different duration of charging under active type condition collect, obtain conversing circuits frequency respectively fand damping time constant τ, then finally obtain the conversing circuits characterisitic parameter determining scope;

Conversing circuits inductance L is:

Conversing circuits inductance L is reactor inductance, capacitor inductance and line inductance sum;

The damping resistance R of conversing circuits is:

。

2. super, extra-high voltage direct-current isolating switch conversing circuits characterisitic parameter method of testing according to claim 1, it is characterized in that, when the characterisitic parameter of active type conversing circuits is tested, described external DC charging power supply U is also parallel with monitoring voltage Table V.

3. super, extra-high voltage direct-current isolating switch conversing circuits characterisitic parameter method of testing according to claim 2, it is characterized in that, described oscillograph model is Tektronix DPO3012, and Luo-coil model is CL-2000, and external DC charging power supply model is SCDC1000/10.