阅读说明：本技术 一种换流阀阻尼电容器用加速寿命试验装置及控制方法 (Accelerated life test device for converter valve damping capacitor and control method ) 是由 雷朝煜 郝良收 熊银武 柴斌 周亮 魏孟刚 郝菁菁 崔春艳 张宇宁 于 2021-04-28 设计创作，主要内容包括：本发明涉及一种换流阀阻尼电容器用加速寿命试验装置及控制方法,包括：充电单元、次级整流器、限流电阻R-1、电压采样回路、放电回路、控制单元和温控箱。本发明提供的技术方案,可以实现不同加速因子在较短时间内进行换流阀阻尼电容器的加速寿命试验,节约试验时间和资源,同时能够真实模拟实际电气应力,保证加速寿命试验的等效性和一致性。(The invention relates to an accelerated life test device for a converter valve damping capacitor and a control method, wherein the accelerated life test device comprises the following steps: charging unit, secondary rectifier and current limiting resistor R 1 The device comprises a voltage sampling loop, a discharging loop, a control unit and a temperature control box. The technical scheme provided by the invention can realize accelerated life test of the converter valve damping capacitor by different acceleration factors in a short time, save test time and resources, and simultaneously can truly simulate actual electrical stress and ensure the equivalence and consistency of the accelerated life test.)

1. An accelerated life test device for a converter valve damping capacitor is characterized by comprising: charging unit, secondary rectifier and current limiting resistor R₁The device comprises a voltage sampling loop, a discharge loop, a control unit and a temperature control box;

the charging unit is connected to an alternating current input end of a secondary rectifier, the charging unit is used for outputting constant resonant current, and the secondary rectifier is used for rectifying the constant resonant current input by the charging unit to output constant current;

the current limiting resistor R₁One end of the secondary rectifier is connected with the direct current output end of the secondary rectifier, and the other end of the secondary rectifier is connected with the voltage sampling loop;

the voltage sampling loop and the discharging loop are connected in parallel at two ends of the secondary rectifier, the voltage sampling loop is used for collecting voltages at two ends of a capacitor to be detected, and the discharging loop is used for discharging the capacitor to be detected;

the discharging loop is connected in parallel with a capacitor C to be measured_sBoth ends of (a);

the control unit is respectively connected with the charging unit, the voltage sampling circuit and the discharging circuit and is used for controlling the charging and discharging of the capacitor to be tested and outputting the capacitor C to be tested_sThe expected service life of;

the temperature control box is connected with the control unit, a capacitor to be tested is placed in the temperature control box, and the capacitor to be tested is used for arranging a capacitor C to be tested_sThe experimental temperature of (1).

2. The apparatus of claim 1, wherein the charging unit comprises: DC power supply U_dcD.C. double-pole contactor K₁Inverter, series resonant capacitor C₁Series resonant reactance L₁And a transformer T;

the DC power supply U_dcThe anode passes through a bipolar direct current contactor K₁Connected to the anode common terminal of the inverter, a DC power supplyU_dcThe negative pole passes through a bipolar direct current contactor K₁Connecting to the cathode common terminal of the inverter;

the series resonance reactance L₁And series resonant capacitor C₁Are respectively connected in series with two ends of the primary side of the transformer T, and the series resonance reactance L₁And series resonant capacitor C₁The other ends of the two-phase inverter are respectively connected with an inverter;

and the secondary side of the transformer T is connected with the alternating current input end of the secondary rectifier.

3. The apparatus of claim 2, wherein the inverter is powered by a first turn-off device S₁A second turn-off device S₂A third turn-off device S₃A fourth turn-off device S₄A first freewheeling diode D₁A second freewheeling diode D₂A third freewheeling diode D₃And a fourth freewheeling diode D₄Composition is carried out;

said first turn-off device S₁A second turn-off device S₂A third turn-off device S₃And a fourth turn-off device S₄Are respectively connected with the first freewheeling diode D₁A second freewheeling diode D₂A third freewheeling diode D₃And a fourth freewheeling diode D₄Anti-parallel connection;

said first turn-off device S₁And a fourth turn-off device S₄Connected in series to form a first series loop, a second turn-off device S₂And a third turn-off device S₃The first series circuit and the second series circuit are connected in parallel;

the series resonance reactance L₁Has one end connected to the first turn-off device S₁And the fourth turn-off device S₄The anode connection point of (a);

the series resonance capacitor C₁Has one end connected to the second turn-off device S₂And the third turn-off device S₃The anode connection point of (a);

said first turn-off device S₁A second turn-off deviceS₂The anode common terminal passes through a bipolar direct current contactor K₁And a DC power supply U_dcConnecting the positive electrode;

said third turn-off device S₃And a fourth turn-off device S₄The cathode common terminal passes through a bipolar direct current contactor K₁And a DC power supply U_dcAnd connecting the negative electrode.

4. The apparatus of claim 2, wherein the secondary rectifier is formed by a first rectifying diode d₁A second rectifying diode d₂A third rectifying diode d₃And a fourth rectifying diode d₄Composition is carried out;

the first rectifying diode d₁And a third rectifying diode d₃A third series circuit formed by series connection of the second rectifying diode d₂And a fourth rectifying diode d₄The third series circuit and the fourth series circuit are connected in parallel.

5. The apparatus of claim 4, wherein the charging unit is coupled to an AC input of a secondary rectifier, comprising:

the secondary side of the transformer T in the charging unit is respectively connected with the first rectifying diode d of the secondary rectifier₁And a third rectifying diode d₃And a second rectifying diode d₂And a fourth rectifying diode d₄The connection point of (a).

6. The apparatus of claim 3, wherein the control unit being coupled to the charging unit comprises:

the control unit outputs a PWM control pulse signal and a first turn-off device S in the charging unit₁A second turn-off device S₂A third turn-off device S₃And a fourth turn-off device S₄For controlling the turn-on and turn-off of the turn-off device.

7. The device of claim 1Wherein the voltage sampling loop is formed by a resistor R₂And a resistor R₃Are connected in series;

a resistor R in the voltage sampling loop₂One end of the resistor is connected into a current limiting resistor R₁And capacitor C to be tested_sCommon connection point of (3), resistor R₃One end of the capacitor C is connected into the capacitor C to be measured_sThe other end of (a);

the resistor R₂And a resistance R₃Common connection point output capacitor C to be tested_sTerminal voltage division signals;

the first input interface of the control unit is connected with a resistor R₂And a resistance R₃For obtaining a voltage sample signal.

8. The apparatus of claim 1, wherein the discharge loop is formed by a resistor R₄Is connected with a thyristor SCR in series;

the first output interface of the control unit is connected with the gate pole of the thyristor SCR and used for transmitting the trigger signal to the gate pole of the thyristor SCR, and the thyristor is conducted to be the capacitor C to be tested_sDischarging;

the resistor R₄The resistance value of the valve can be adjusted.

9. The method for controlling a test device according to any one of claims 1 to 8, wherein the method comprises:

step 1: the control unit controls the temperature of the temperature control box to rise to the experimental temperature T_s；

Step 2: the control unit outputs a PWM pulse signal to control the charging unit to output constant resonance current, and the constant resonance current is input into the alternating current input end of the secondary rectifier, so that the direct current output end of the secondary rectifier outputs constant current I_C；

And step 3: capacitor C to be tested_sAt a constant current I_CCharging to the capacitor C to be measured_sIs raised to a target value U_sWhen the control unit receives the voltage collected by the voltage sampling loop and equals to the target value signal, the output of the PWM pulse signal is stoppedAnd recording the charging time as t_c；

And 4, step 4: capacitor C to be tested_sIs maintained at a target value U_SAnd the holding time is t_s；

And 5: the control unit outputs PWM pulse signals to control the conduction of a thyristor in a discharge loop, so that the capacitor C to be tested_sDischarging until the voltage is zero, and recording the discharge time as t_f；

Step 6: capacitor C to be tested after discharge_sThe voltage and the charging current are kept at zero and the holding time is t_k；

And 7: obtaining the capacitor C to be measured at the current moment_sAnd judging the capacitor C to be measured at the current moment_sIf so, the control unit outputs the service life of the capacitor to be tested according to the duration of the whole accelerated life test, the target value of the test voltage and the test temperature of the capacitor to be tested, otherwise, the step 2 is returned.

10. The method of claim 9, wherein the controlling unit outputs a PWM pulse signal to control the charging unit to output a constant resonant current, comprising:

step a: the control unit controls the constant current I_CInputting the difference value of the corresponding current effective value and the target current value into a PI controller to obtain a PIout signal;

step b: subtracting the PIout signal from a triangular carrier signal zb1 and a triangular carrier signal zb2 in the PWM pulse signal output by the control unit respectively to obtain a difference signal z13 and a difference signal z 24;

step c: zero-crossing comparison is performed between the difference signal z13 and the difference signal z24, and the first turn-off device S is controlled when the difference signal z13 is greater than zero and the difference signal z24 is less than zero₁And a third turn-off device S₃On, the second turn-off device S₂And a fourth turn-off device S₄Turning off;

when the difference signal z13 is less than zero and the difference signal z24 is greater than zero, the first turn-off device S is controlled₁And a third turn-off deviceS₃Off, second turn-off device S₂And a fourth turn-off device S₄Conducting;

step d: based on a first turn-off device S in the charging unit₁And a third turn-off device S₃On, the second turn-off device S₂And a fourth turn-off device S₄Shut-off or first shut-off device S₁And a third turn-off device S₃Off, second turn-off device S₂And a fourth turn-off device S₄And conducting, and carrying out inversion processing on the current output by the direct current power supply so as to enable the charging unit to output constant resonant current.

11. The method of claim 9, wherein the lifetime τ of the capacitor under test₀The calculation formula of (a) is as follows:

in the above formula, τ_sFor the duration of the entire accelerated life test, U_sFor the experimental voltage target value, U₀For the operating voltage of the capacitor to be measured, T_sFor the experimental temperature, T, of the capacitor to be measured₀And a is the voltage proportion index, namely the working temperature of the capacitor to be measured.

12. The method of claim 10, wherein the triangular carrier signal zb1 is 180 degrees out of phase with triangular carrier signal zb 2.

Technical Field

The invention relates to the field of power equipment testing, in particular to an accelerated life testing device for a converter valve damping capacitor and a control method.

Background

The high-voltage direct-current transmission has unique advantages in long-distance and large-capacity transmission, and is an effective way for solving the problem of uneven energy distribution and optimizing resource allocation. At present, the established and established high-voltage direct-current transmission project has a certain scale, the transmission capacity and the voltage level are gradually improved, the role of the high-voltage direct-current transmission project in a power grid is more and more important, and the safety and stability problems are highly concerned and researched. The converter valve is core equipment of a direct current transmission project, the power is controlled by connecting three-phase alternating current voltage to a direct current end in sequence to obtain expected direct current voltage, and the value of the converter valve accounts for 22-25% of the total price of complete equipment of a converter station. The converter valve comprises unit components such as a thyristor, a damping capacitor, a damping resistor, a saturable reactor and a trigger plate. The damping capacitor can reduce continuous voltage peak values including phase conversion overshoot, dynamic voltage sharing in the opening and closing processes of the valve group is achieved, the damping loss of the converter valve is minimized, and safe and stable operation of the converter valve is guaranteed.

The self-healing capacitor is widely applied to the design of the converter valve damping unit due to the characteristics and advantages, and the capacitance value of the self-healing capacitor is in the mu F magnitude. After the self-healing capacitor is aged, the capacitance value is lost, the damping voltage-sharing function is reduced, the adverse effect is brought to the operation of the converter valve, and even the forced shutdown of the equipment is caused. The converter valve damping capacitor is special in application environment, and is required to have high bearing capacity of effective value current and peak current and to be capable of dealing with high voltage and current change rate. The existing capacitor life testing device has inaccurate testing result and long testing time, so the accuracy and the rapidity of the testing of the capacitor life testing device need to be improved urgently.

Disclosure of Invention

Aiming at the defects of the prior art, the invention aims to provide an accelerated life test device for a damping capacitor of a converter valve, which can accurately and quickly test the service life of the capacitor.

The test device specifically includes:

charging unit, secondary rectifier and current limiting resistor R₁The device comprises a voltage sampling loop, a discharge loop, a control unit and a temperature control box;

the charging unit is connected to an alternating current input end of a secondary rectifier, the charging unit is used for outputting constant resonant current, and the secondary rectifier is used for rectifying the constant resonant current input by the charging unit to output constant current;

the current limiting resistor R₁One end of the secondary rectifier is connected with the direct current output end of the secondary rectifier, and the other end of the secondary rectifier is connected with the voltage sampling loop;

the voltage sampling loop and the discharging loop are connected in parallel at two ends of the secondary rectifier, the voltage sampling loop is used for collecting voltages at two ends of a capacitor to be detected, and the discharging loop is used for discharging the capacitor to be detected;

the discharging loop is connected in parallel with a capacitor C to be measured_sBoth ends of (a);

the control unit is respectively connected with the charging unit, the voltage sampling circuit and the discharging circuit and is used for controlling the charging and discharging of the capacitor to be tested and outputting the capacitor C to be tested_sThe expected service life of;

the temperature control box is connected with the control unit, a capacitor to be tested is placed in the temperature control box, and the capacitor to be tested is used for arranging a capacitor C to be tested_sThe experimental temperature of (1).

Preferably, the charging unit includes: DC power supply U_dcD.C. double-pole contactor K₁Inverter, series resonant capacitor C₁Series resonant reactance L₁And a transformer T;

the DC power supply U_dcThe anode passes through a bipolar direct current contactor K₁Connected to the anode common terminal of the inverter, a DC power supply U_dcThe negative pole passes through a bipolar direct current contactor K₁Connecting to the cathode common terminal of the inverter;

the series resonance reactance L₁And series resonant capacitor C₁Are respectively connected in series with two ends of the primary side of the transformer T, and the series resonance reactance L₁And series resonant capacitor C₁The other ends of the two-phase inverter are respectively connected with an inverter;

and the secondary side of the transformer T is connected with the alternating current input end of the secondary rectifier.

Further, the inverter is composed of a first turn-off device S₁A second turn-off device S₂A third turn-off device S₃A fourth turn-off device S₄A first freewheeling diode D₁A second freewheeling diode D₂A third freewheeling diode D₃And a fourth freewheeling diode D₄Composition is carried out;

said first turn-off device S₁A second turn-off device S₂A third turn-off device S₃And a fourth turn-off device S₄Are respectively connected with the first freewheeling diode D₁A second freewheeling diode D₂A third freewheeling diode D₃And a fourth freewheeling diode D₄Anti-parallel connection;

said first turn-off device S₁And a fourth turn-off device S₄Connected in series to form a first series loop, a second turn-off device S₂And a third turn-off device S₃The first series circuit and the second series circuit are connected in parallel;

the series resonance reactance L₁Has one end connected to the first turn-off device S₁And the fourth turn-off device S₄The anode connection point of (a);

the series resonance capacitor C₁One end of the first switch is connected to the second switchTurn-off device S₂And the third turn-off device S₃The anode connection point of (a);

said first turn-off device S₁A second turn-off device S₂The anode common terminal passes through a bipolar direct current contactor K₁And a DC power supply U_dcConnecting the positive electrode;

said third turn-off device S₃And a fourth turn-off device S₄The cathode common terminal passes through a bipolar direct current contactor K₁And a DC power supply U_dcAnd connecting the negative electrode.

Further, the secondary rectifier is composed of a first rectifying diode d₁A second rectifying diode d₂A third rectifying diode d₃And a fourth rectifying diode d₄Composition is carried out;

the first rectifying diode d₁And a third rectifying diode d₃A third series circuit formed by series connection of the second rectifying diode d₂And a fourth rectifying diode d₄The third series circuit and the fourth series circuit are connected in parallel.

Further, the charging unit is connected to the ac input terminal of the secondary rectifier, and includes:

the secondary side of the transformer T in the charging unit is respectively connected with the first rectifying diode d of the secondary rectifier₁And a third rectifying diode d₃And a second rectifying diode d₂And a fourth rectifying diode d₄The connection point of (a).

Further, the control unit is connected with the charging unit and comprises:

the control unit outputs a PWM control pulse signal and a first turn-off device S in the charging unit₁A second turn-off device S₂A third turn-off device S₃And a fourth turn-off device S₄For controlling the turn-on and turn-off of the turn-off device.

Preferably, the voltage sampling loop is composed of a resistor R₂And a resistor R₃Are connected in series;

the voltage samplingResistance R in the loop₂One end of the resistor is connected into a current limiting resistor R₁And capacitor C to be tested_sCommon connection point of (3), resistor R₃One end of the capacitor C is connected into the capacitor C to be measured_sThe other end of (a);

the resistor R₂And a resistance R₃Common connection point output capacitor C to be tested_sTerminal voltage division signals;

the first input interface of the control unit is connected with a resistor R₂And a resistance R₃For obtaining a voltage sample signal.

Preferably, the discharge loop is composed of a resistor R₄Is connected with a thyristor SCR in series;

the first output interface of the control unit is connected with the gate pole of the thyristor SCR and used for transmitting the trigger signal to the gate pole of the thyristor SCR, and the thyristor is conducted to be the capacitor C to be tested_sDischarging;

the resistor R₄The resistance value of the valve can be adjusted.

The invention provides a control method of an accelerated life test device for a damping capacitor of a converter valve based on the same invention concept, which comprises the following steps:

step 1: the control unit controls the temperature of the temperature control box to rise to the experimental temperature T_s；

Step 2: the control unit outputs a PWM pulse signal to control the charging unit to output constant resonance current, and the constant resonance current is input into the alternating current input end of the secondary rectifier, so that the direct current output end of the secondary rectifier outputs constant current I_C；

And step 3: capacitor C to be tested_sAt a constant current I_CCharging to the capacitor C to be measured_sIs raised to a target value U_sWhen the control unit receives a voltage collected by the voltage sampling loop and equals to a target value signal, the control unit stops outputting the PWM pulse signal and records the charging time as t_c；

And 4, step 4: capacitor C to be tested_sIs maintained at a target value U_sAnd the holding time is t_s；

And 5: control ofThe unit outputs PWM pulse signal to control the conduction of thyristor in the discharge loop, so that the capacitor C to be tested_sDischarging until the voltage is zero, and recording the discharge time as t_f；

Step 6: capacitor C to be tested after discharge_sThe voltage and the charging current are kept at zero and the holding time is t_k；

And 7: obtaining the capacitor C to be measured at the current moment_sAnd judging the capacitor C to be measured at the current moment_sIf so, the control unit outputs the service life of the capacitor to be tested according to the duration of the whole accelerated life test, the target value of the test voltage and the test temperature of the capacitor to be tested, otherwise, the step 2 is returned.

Preferably, the controlling unit outputs a PWM pulse signal to control the charging unit to output a constant resonant current, including:

step a: the control unit controls the constant current I_CInputting the difference value of the corresponding current effective value and the target current value into a PI controller to obtain a PIout signal;

step b: subtracting the PIout signal from a triangular carrier signal zb1 and a triangular carrier signal zb2 in the PWM pulse signal output by the control unit respectively to obtain a difference signal z13 and a difference signal z 24;

step c: zero-crossing comparison is performed between the difference signal z13 and the difference signal z24, and the first turn-off device S is controlled when the difference signal z13 is greater than zero and the difference signal z24 is less than zero₁And a third turn-off device S₃On, the second turn-off device S₂And a fourth turn-off device S₄Turning off;

when the difference signal z13 is less than zero and the difference signal z24 is greater than zero, the first turn-off device S is controlled₁And a third turn-off device S₃Off, second turn-off device S₂And a fourth turn-off device S₄Conducting;

step d: based on a first turn-off device S in the charging unit₁And a third turn-off device S₃On, the second turn-off device S₂And a fourth turn-off device S₄Switch offOr the first turn-off device S₁And a third turn-off device S₃Off, second turn-off device S₂And a fourth turn-off device S₄And conducting, and carrying out inversion processing on the current output by the direct current power supply so as to enable the charging unit to output constant resonant current.

Preferably, the service life tau of the capacitor to be tested₀The calculation formula of (a) is as follows:

in the above formula, τ_sFor the duration of the entire accelerated life test, U_sFor the experimental voltage target value, U₀For the operating voltage of the capacitor to be measured, T_sFor the experimental temperature, T, of the capacitor to be measured₀And a is the voltage proportion index, namely the working temperature of the capacitor to be measured.

Further, the phase difference between the triangular carrier signal zb1 and the triangular carrier signal zb2 is 180 degrees.

Compared with the closest prior art, the invention has the following beneficial effects:

the invention provides an accelerated life test device for a converter valve damping capacitor and a control method, wherein the accelerated life test device comprises the following steps: charging unit, secondary rectifier and current limiting resistor R₁The device comprises a voltage sampling loop, a discharge loop, a control unit and a temperature control box; the charging unit is connected to an alternating current input end of a secondary rectifier, the charging unit is used for outputting constant resonant current, and the secondary rectifier is used for rectifying the constant resonant current input by the charging unit to output constant current; the current limiting resistor R₁One end of the secondary rectifier is connected with the direct current output end of the secondary rectifier, and the other end of the secondary rectifier is connected with the voltage sampling loop; the voltage sampling loop and the discharging loop are connected in parallel at two ends of the secondary rectifier, the voltage sampling loop is used for collecting voltages at two ends of a capacitor to be detected, and the discharging loop is used for discharging the capacitor to be detected; the discharging loop is connected in parallel with a capacitor C to be measured_sBoth ends of (a); the control unit is respectively connected with the charging unit and the voltage sampling circuitThe circuit is connected with the discharge loop and used for controlling the charge and discharge of the capacitor to be tested and outputting the capacitor C to be tested_sThe expected service life of; the temperature control box is connected with the control unit, a capacitor to be tested is placed in the temperature control box, and the capacitor to be tested is used for arranging a capacitor C to be tested_sThe experimental temperature of (2); the technical scheme provided by the invention can be used for carrying out the accelerated life test of the converter valve damping capacitor in a short time, so that the test time and resources are saved, the experimental environment can be truly simulated, and the equivalence and consistency of the accelerated life test are ensured.

Drawings

FIG. 1 is a circuit diagram of an accelerated life testing apparatus for a damping capacitor of a converter valve provided in an embodiment of the present invention;

FIG. 2 is a flowchart of a control method of an accelerated life testing apparatus for a converter valve damping capacitor according to an embodiment of the present invention;

FIG. 3 is a schematic diagram illustrating an automatic test of voltage, current, stress and capacitance parameters of a capacitor under test according to an embodiment of the present invention;

FIG. 4 is a schematic diagram illustrating an automatic adjustment of a charging current of a capacitor under test according to an embodiment of the present invention;

FIG. 5 is a schematic diagram illustrating an automatic adjustment of a discharging current of a capacitor under test according to an embodiment of the present invention;

fig. 6 is a schematic diagram illustrating a calculation of the service life of the capacitor under test according to the embodiment of the present invention.

Detailed Description

The following describes embodiments of the present invention in further detail with reference to the accompanying drawings.

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.

Example 1

Referring to fig. 1, fig. 1 is a main structural block diagram of an accelerated life testing apparatus for a converter valve damping capacitor according to an embodiment of the present invention. As shown in fig. 1, the accelerated life test apparatus for a converter valve damping capacitor in the embodiment of the present invention mainly includes: charging unit, secondary rectifier and current limiting resistor R₁The device comprises a voltage sampling loop, a discharge loop, a control unit and a temperature control box;

the charging unit is connected to an alternating current input end of a secondary rectifier, the charging unit is used for outputting constant resonant current, and the secondary rectifier is used for rectifying the constant resonant current input by the charging unit to output constant current;

the current limiting resistor R₁One end of the secondary rectifier is connected with the direct current output end of the secondary rectifier, and the other end of the secondary rectifier is connected with the voltage sampling loop;

the voltage sampling loop and the discharging loop are connected in parallel at two ends of the secondary rectifier, the voltage sampling loop is used for collecting voltages at two ends of a capacitor to be detected, and the discharging loop is used for discharging the capacitor to be detected;

the discharging loop is connected in parallel with a capacitor C to be measured_sBoth ends of (a);

the control unit is respectively connected with the charging unit, the voltage sampling circuit and the discharging circuit and is used for controlling the charging and discharging of the capacitor to be tested and outputting the capacitor C to be tested_sThe expected service life of;

the temperature control box is connected with the control unit, a capacitor to be tested is placed in the temperature control box, and the capacitor to be tested is used for arranging a capacitor C to be tested_sThe experimental temperature of (1).

In this embodiment, the charging unit includes: DC power supply U_dcD.C. double-pole contactor K₁Inverter, series resonant capacitor C₁Series resonant reactance L₁And a transformer T;

the DC power supply U_dcThe anode passes through a bipolar direct current contactor K₁Connected to the anode common terminal of the inverter, a DC power supply U_dcThe negative pole passes through a bipolar direct current contactor K₁Cathode connected to inverterA pole common terminal;

the series resonance reactance L₁And series resonant capacitor C₁Are respectively connected in series with two ends of the primary side of the transformer T, and the series resonance reactance L₁And series resonant capacitor C₁The other ends of the two-phase inverter are respectively connected with an inverter;

and the secondary side of the transformer T is connected with the alternating current input end of the secondary rectifier.

Wherein the inverter is composed of a first turn-off device S₁A second turn-off device S₂A third turn-off device S₃A fourth turn-off device S₄A first freewheeling diode D₁A second freewheeling diode D₂A third freewheeling diode D₃And a fourth freewheeling diode D₄Composition is carried out;

said first turn-off device S₁A second turn-off device S₂A third turn-off device S₃And a fourth turn-off device S₄Are respectively connected with the first freewheeling diode D₁A second freewheeling diode D₂A third freewheeling diode D₃And a fourth freewheeling diode D₄Anti-parallel connection;

said first turn-off device S₁And a fourth turn-off device S₄Connected in series to form a first series loop, a second turn-off device S₂And a third turn-off device S₃The first series circuit and the second series circuit are connected in parallel;

the series resonance reactance L₁Has one end connected to the first turn-off device S₁And the fourth turn-off device S₄The anode connection point of (a);

the series resonance capacitor C₁Has one end connected to the second turn-off device S₂And the third turn-off device S₃The anode connection point of (a);

said first turn-off device S₁A second turn-off device S₂The anode common terminal passes through a bipolar direct current contactor K₁And a DC power supply U_dcConnecting the positive electrode;

the thirdTurn-off device S₃And a fourth turn-off device S₄The cathode common terminal passes through a bipolar direct current contactor K₁And a DC power supply U_dcAnd connecting the negative electrode.

The secondary rectifier is composed of a first rectifying diode d₁A second rectifying diode d₂A third rectifying diode d₃And a fourth rectifying diode d₄Composition is carried out;

the first rectifying diode d₁And a third rectifying diode d₃A third series circuit formed by series connection of the second rectifying diode d₂And a fourth rectifying diode d₄The third series circuit and the fourth series circuit are connected in parallel.

Specifically, the charging unit is connected to an ac input terminal of the secondary rectifier, and includes:

the secondary side of the transformer T in the charging unit is respectively connected with the first rectifying diode d of the secondary rectifier₁And a third rectifying diode d₃And a second rectifying diode d₂And a fourth rectifying diode d₄The connection point of (a).

Specifically, the control unit is connected with the charging unit and includes:

the control unit outputs a PWM control pulse signal and a first turn-off device S in the charging unit₁A second turn-off device S₂A third turn-off device S₃And a fourth turn-off device S₄For controlling the turn-on and turn-off of the turn-off device.

In this embodiment, the voltage sampling loop is composed of a resistor R₂And a resistor R₃Are connected in series;

a resistor R in the voltage sampling loop₂One end of the resistor is connected into a current limiting resistor R₁And capacitor C to be tested_sCommon connection point of (3), resistor R₃One end of the capacitor C is connected into the capacitor C to be measured_sThe other end of (a);

the resistor R₂And a resistance R₃Common connection point output capacitor C to be tested_sTerminal voltage division signals;

the first input interface of the control unit is connected with a resistor R₂And a resistance R₃For obtaining a voltage sample signal.

In this embodiment, the discharge loop is formed by a resistor R₄Is connected with a thyristor SCR in series;

the first output interface of the control unit is connected with the gate pole of the thyristor SCR and used for transmitting the trigger signal to the gate pole of the thyristor SCR, and the thyristor is conducted to be the capacitor C to be tested_sDischarging;

the resistor R₄The resistance value of the valve can be adjusted.

Example 2

Based on the experimental device, the invention also provides a control method of the accelerated life test device for the converter valve damping capacitor, as shown in fig. 2, the method comprises the following steps:

step 1: the control unit controls the temperature of the temperature control box to rise to the experimental temperature T_s；

Step 2: the control unit outputs a PWM pulse signal to control the charging unit to output constant resonance current, and the constant resonance current is input into the alternating current input end of the secondary rectifier, so that the direct current output end of the secondary rectifier outputs constant current I_C；

And step 3: capacitor C to be tested_sAt a constant current I_CCharging to the capacitor C to be measured_sIs raised to a target value U_sWhen the control unit receives a voltage collected by the voltage sampling loop and equals to a target value signal, the control unit stops outputting the PWM pulse signal and records the charging time as t_c；

And 4, step 4: capacitor C to be tested_sIs maintained at a target value U_SAnd the holding time is t_s；

And 5: the control unit outputs PWM pulse signals to control the conduction of a thyristor in a discharge loop, so that the capacitor C to be tested_sDischarging until the voltage is zero, and recording the discharge time as t_f；

Step 6: capacitor C to be tested after discharge_sThe voltage and the charging current are kept at zero andduration of time t_k；

And 7: obtaining the capacitor C to be measured at the current moment_sAnd judging the capacitor C to be measured at the current moment_sIf so, the control unit outputs the service life of the capacitor to be tested according to the duration of the whole accelerated life test, the target value of the test voltage and the test temperature of the capacitor to be tested, otherwise, the step 2 is returned.

In this embodiment, as shown in FIG. 3, the capacitor C to be measured is charged and discharged_sAt a constant current I_CCharging to the capacitor C to be measured_sIs raised to a target value U_sWhen the control unit receives a voltage collected by the voltage sampling loop and equals to a target value signal, the control unit stops outputting the PWM pulse signal and records the charging time as t_c(ii) a Capacitor C to be tested_sIs maintained at a target value U_sAnd the holding time is t_s(ii) a The control unit outputs PWM pulse signals to control the conduction of a thyristor in a discharge loop, so that the capacitor C to be tested_sDischarging until the voltage is zero, and recording the discharge time as t_f(ii) a Capacitor C to be tested after discharge_sThe voltage and the charging current are kept at zero and the holding time is t_k；

Obtaining the capacitor C to be measured at the current moment_sAnd judging the capacitor C to be measured at the current moment_sIf so, the control unit outputs the service life of the capacitor to be tested according to the duration of the whole accelerated life test, the target value of the test voltage and the test temperature of the capacitor to be tested, otherwise, the control unit continues to perform the charge-discharge behavior for testing.

Wherein, the capacitor C to be tested_sThe capacitance of (a) is calculated as follows:

in the formula of U_sIs a voltage target value, I_CIs a constant current.

In this embodiment, the control unit outputs a PWM pulse signal to control the charging unit to output a constant resonant current, as shown in fig. 4, including:

step a: the control unit controls the constant current I_CInputting the difference value Iout between the corresponding current effective value Ic-rms and the target current value Irms-set into a PI controller to obtain a PIout signal;

step b: subtracting the PIout signal from a triangular carrier signal zb1 and a triangular carrier signal zb2 in the PWM pulse signal output by the control unit respectively to obtain a difference signal z13 and a difference signal z 24;

step c: zero-crossing comparison is performed between the difference signal z13 and the difference signal z24, and the first turn-off device S is controlled when the difference signal z13 is greater than zero and the difference signal z24 is less than zero₁And a third turn-off device S₃On, the second turn-off device S₂And a fourth turn-off device S₄Turning off;

when the difference signal z13 is less than zero and the difference signal z24 is greater than zero, the first turn-off device S is controlled₁And a third turn-off device S₃Off, second turn-off device S₂And a fourth turn-off device S₄Conducting;

step d: based on a first turn-off device S in the charging unit₁And a third turn-off device S₃On, the second turn-off device S₂And a fourth turn-off device S₄Shut-off or first shut-off device S₁And a third turn-off device S₃Off, second turn-off device S₂And a fourth turn-off device S₄And conducting, and carrying out inversion processing on the current output by the direct current power supply so as to enable the charging unit to output constant resonant current.

In this embodiment, the control unit outputs the PWM pulse signal to control the conduction of the thyristor in the discharging loop, so that the capacitor C to be tested_sDischarge until voltage is zero due to R₄The resistance and, hence, the discharge current is continuously adjustable, as shown in fig. 5, when the resistor R is₄When the discharge resistance takes different values, the discharge current of the capacitor to be tested has different discharge current peak values i_peak1And i_peak1。

In the present embodiment, as shown in fig. 6, the control unit outputs the service life of the capacitor to be tested according to the duration of the entire accelerated life test of the experimental loop, the experimental voltage target value and the experimental temperature of the capacitor to be tested; wherein the service life tau of the capacitor to be tested₀The calculation formula of (a) is as follows:

in the above formula, τ_sFor the duration of the entire accelerated life test, U_sFor the experimental voltage target value, U₀For the operating voltage of the capacitor to be measured, T_sFor the experimental temperature, T, of the capacitor to be measured₀And a is the voltage proportion index, namely the working temperature of the capacitor to be measured.

Further, the phase difference between the triangular carrier signal zb1 and the triangular carrier signal zb2 is 180 degrees.

The experimental device provided by the invention can be used for carrying out the accelerated life test of the damping capacitor of the converter valve in a short time, so that the test time and resources are saved, the applied voltage and the ambient temperature of the capacitor to be tested are adjustable, the accelerated life test under different acceleration factors is realized, and meanwhile, the charging and discharging current of the capacitor to be tested is adjustable, so that the actual electrical stress can be truly simulated, and the equivalence and the consistency of the accelerated life test are ensured; the capacitance value parameters of the capacitor to be tested can be automatically tested and recorded regularly, the test can be automatically stopped after the capacitor of the sample is detected to be invalid, the workload of testing personnel is reduced, the interruption of the test process is avoided, the automation degree is high, the test time is greatly shortened, and the method can be widely applied to the performance test of the damping capacitor of the converter valve.

As will be appreciated by one skilled in the art, embodiments of the present application may be provided as a method, system, or computer program product. Accordingly, the present application may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Furthermore, the present application may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, and the like) having computer-usable program code embodied therein.

The present application is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the application. It will be understood that each flow and/or block of the flow diagrams and/or block diagrams, and combinations of flows and/or blocks in the flow diagrams and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.

These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function specified in the flowchart flow or flows and/or block diagram block or blocks.

These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.

Finally, it should be noted that: the above embodiments are only for illustrating the technical solutions of the present invention and not for limiting the same, and although the present invention is described in detail with reference to the above embodiments, those of ordinary skill in the art should understand that: modifications and equivalents may be made to the embodiments of the invention without departing from the spirit and scope of the invention, which is to be covered by the claims.