CN114167278A - Flexible direct-current transmission voltage source converter valve test method and power supply device - Google Patents

Flexible direct-current transmission voltage source converter valve test method and power supply device Download PDF

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Publication number
CN114167278A
CN114167278A CN202210126861.9A CN202210126861A CN114167278A CN 114167278 A CN114167278 A CN 114167278A CN 202210126861 A CN202210126861 A CN 202210126861A CN 114167278 A CN114167278 A CN 114167278A
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China
Prior art keywords
converter valve
voltage source
voltage
power supply
test
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CN202210126861.9A
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CN114167278B (en
Inventor
胡应宏
蔡巍
卢毅
宋鹏
朱守舵
杨大伟
龙凯华
李�雨
辛光明
王炳辉
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State Grid Corp of China SGCC
North China Electric Power Research Institute Co Ltd
Electric Power Research Institute of State Grid Jibei Electric Power Co Ltd
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State Grid Corp of China SGCC
North China Electric Power Research Institute Co Ltd
Electric Power Research Institute of State Grid Jibei Electric Power Co Ltd
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Priority to CN202210126861.9A priority Critical patent/CN114167278B/en
Publication of CN114167278A publication Critical patent/CN114167278A/en
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Publication of CN114167278B publication Critical patent/CN114167278B/en
Priority to PCT/CN2023/075084 priority patent/WO2023151607A1/en
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
    • G01R31/327—Testing of circuit interrupters, switches or circuit-breakers
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
    • G01R31/12—Testing dielectric strength or breakdown voltage ; Testing or monitoring effectiveness or level of insulation, e.g. of a cable or of an apparatus, for example using partial discharge measurements; Electrostatic testing
    • G01R31/1227—Testing dielectric strength or breakdown voltage ; Testing or monitoring effectiveness or level of insulation, e.g. of a cable or of an apparatus, for example using partial discharge measurements; Electrostatic testing of components, parts or materials
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
    • G01R31/26—Testing of individual semiconductor devices
    • G01R31/2601—Apparatus or methods therefor
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M1/00—Details of apparatus for conversion
    • H02M1/32—Means for protecting converters other than automatic disconnection
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
    • H02M7/02—Conversion of ac power input into dc power output without possibility of reversal
    • H02M7/04—Conversion of ac power input into dc power output without possibility of reversal by static converters
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/60—Arrangements for transfer of electric power between AC networks or generators via a high voltage DC link [HVCD]

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Inverter Devices (AREA)
  • Rectifiers (AREA)

Abstract

The invention provides a test method and a power supply device for a converter valve of a flexible direct-current transmission voltage source, wherein the method comprises the following steps: connecting the positive electrode, ground or negative electrode connecting end of the voltage source converter valve to be tested to an external test direct current power supply by controlling an isolating switch; controlling an external test direct-current power supply to boost the voltage to charge a capacitor of a converter valve of a voltage source to be tested, and carrying out energy-taking power supply starting voltage test; after the capacitor of the voltage source converter valve to be tested is charged to the rated voltage, a withstand voltage test is carried out; after the withstand voltage test is finished, unlocking the converter valve of the voltage source to be tested, and carrying out an electrical performance test on the converter valve of the voltage source to be tested; and after the electrical performance test is finished, locking the converter valve of the tested voltage source to perform the energy-taking power supply locking test. The invention has simple operation in the test process, low requirement on the performance of equipment and wide application range, is not only suitable for detecting the performance of the sub-modules of the valve section, but also suitable for detecting the performance of a valve tower and a single-pole or double-pole converter valve.

Description

Flexible direct-current transmission voltage source converter valve test method and power supply device
Technical Field
The invention relates to a flexible direct current transmission technology, in particular to a flexible direct current transmission voltage source converter valve test method and a power supply device.
Background
The Modular Multilevel Converter valve (MMC) adopts a controllable turn-off type power electronic device and a Pulse Width Modulation (PWM) technology, can realize independent control of active power and reactive power, can supply power to a passive network, and is a novel Multilevel Converter topological structure. The flexible direct-current power transmission system based on the modular voltage source converter valve can overcome the defects of the traditional silicon controlled direct-current power transmission and has wide application prospect in the fields of connecting a new energy power generation field (such as wind power generation, solar power generation and the like) to a power grid, supplying power to a remote load, constructing an urban load center and the like. Compared with the conventional direct current thyristor valve, the modular multilevel converter valve has the advantages of compactness, modular design, easiness in movement, installation, debugging and maintenance, convenience in expansion, realization of multi-terminal direct current transmission and the like, and becomes an indispensable important component in a future power transmission and distribution system.
The submodule of the power electronic element based on the Insulated Gate Bipolar Transistor (IGBT) is a core element of the MMC converter valve, and in the engineering installation stage, the submodule is very easily influenced by complex transportation environments such as vibration, falling, high and low temperature, humidity and the like in the process of being transported to the site, and in order to ensure that the function of the submodule of the MMC converter valve used in the flexible direct current transmission engineering is normal, the submodule of the MMC converter valve needs to be tested before being installed. In order to shorten the field installation and debugging time, a method for testing a valve section formed by connecting a plurality of sub-modules in series is mostly adopted in a project, or after conditions are met, an unlocking test is carried out on the converter valve from an alternating current system.
In principle, offshore wind power flexible direct current transmission engineering is similar to onshore flexible direct current transmission, and an offshore platform does not have an alternating current power supply point and load of an onshore converter station, so that the offshore wind power flexible direct current transmission engineering and the onshore flexible direct current transmission engineering face different engineering practical problems. The offshore converter station is in an island operation state, and no alternating current system power supply exists in the capital construction stage. And only after the converter valve is in place and the submarine cable is connected, the system test of the converter valve is carried out by the direct-current submarine cable. At this time, the converter valve is not completely tested, and the converter valve cannot be guaranteed to be put into operation completely. Only sufficient and perfect station system tests can ensure the safety of equipment and the smooth operation of system debugging. Continuing to use the commissioning of a land-based converter station, the charging and unlocking of the converter valves via the ac system is not economical and feasible. Finding a power supply and a method suitable for debugging the offshore flexible-direct converter station becomes the biggest difficult problem restricting the offshore flexible-direct debugging, and a new debugging technology and equipment must be found.
Disclosure of Invention
In order to overcome at least one defect of a converter valve test of a flexible direct-current transmission voltage source in the prior art, the invention provides a converter valve test method of the flexible direct-current transmission voltage source, which comprises the following steps:
connecting the positive electrode, ground or negative electrode connecting end of the voltage source converter valve to be tested to an external test direct current power supply by controlling an isolating switch;
controlling the external test direct-current power supply to boost the voltage to charge the capacitor of the tested voltage source converter valve, and testing the starting voltage of the energy taking power supply of the tested voltage source converter valve;
after the capacitor of the converter valve of the voltage source to be tested is charged to the rated voltage, a withstand voltage test is carried out on the converter valve of the voltage source to be tested;
after the withstand voltage test is finished, unlocking the converter valve of the voltage source to be tested, and carrying out an electrical performance test on the converter valve of the voltage source to be tested;
and after the electrical performance test is finished, locking the converter valve of the voltage source to be tested, and carrying out energy taking power supply locking test on the converter valve of the voltage source to be tested.
In the embodiment of the present invention, the connecting end of the positive electrode, the ground or the negative electrode of the converter valve of the voltage source to be measured to be connected to the external test dc power supply by controlling the isolating switch includes:
determining that the power transmission system is a true bipolar flexible direct current power transmission converter, wherein the anode, the ground and the cathode of the external test direct current power supply are respectively connected with the anode, the ground and the cathode connecting ends of the voltage source converter valve to be measured; or, during the positive pole test, the positive pole and the ground of the external test direct current power supply are respectively connected with the positive pole and the ground connecting end of the voltage source converter valve, and the negative pole direct current power supply is suspended and is not connected; during the negative pole test, the negative pole and the ground of the external test direct current power supply are respectively connected with the negative pole and ground connecting end of the voltage source converter valve, and the positive pole direct current power supply is suspended and is not connected;
determining that the power transmission system is a pseudo bipolar flexible direct current power transmission system, wherein the anode, the ground and the cathode of the external test direct current power supply are respectively connected with the anode, the ground and the cathode connecting ends of the voltage source converter valve to be measured;
determining that the power transmission system is a single-pole flexible direct-current power transmission system, when a current converter is a positive pole, the positive pole and the ground of the external test direct-current power supply are respectively connected with the positive pole and ground connecting ends of a voltage source converter valve to be measured, and a negative pole direct-current power supply is suspended and not connected; when the negative pole converter is used, the negative pole and the ground of the external test direct current power supply are respectively connected with the negative pole and ground connecting end of the voltage source converter valve to be tested, and the positive pole direct current power supply is suspended and is not connected.
In the embodiment of the present invention, the controlling the external test dc power supply to boost the voltage to charge the capacitor of the measured voltage source converter valve, and the performing the energy-taking power supply start voltage test on the measured voltage source converter valve includes:
and controlling an external test direct-current power supply to boost the voltage of the minimum energy-taking power supply of the submodule of the tested voltage source converter valve, continuously boosting the voltage of the minimum energy-taking power supply of the submodule to the rated voltage of the tested voltage source converter valve when the number of abnormal modules in the submodule of the converter valve is determined not to exceed a preset redundancy value, and testing the starting voltage of the energy-taking power supply of the submodule according to the detected energy-taking power supply voltage, communication state and capacitance of the submodule of the converter valve in the boosting charging process.
In the embodiment of the present invention, the controlling the external test dc power supply to boost the voltage to charge the capacitor of the measured voltage source converter valve, and the performing the energy-taking power supply start voltage test on the measured voltage source converter valve includes:
and controlling an external direct current power supply to boost the voltage to the rated voltage of the converter valve of the voltage source to be tested, and carrying out energy-taking power supply starting voltage test on a submodule according to the detected energy-taking power supply voltage, communication state and capacitor voltage-sharing of the submodule of the converter valve in the boosting charging process.
In the embodiment of the present invention, after the capacitor of the voltage source converter valve to be tested is charged to the rated voltage, the performing a withstand voltage test on the voltage source converter valve to be tested includes:
after the capacitor of the tested voltage source converter valve is charged to a rated voltage, after the energy-taking power supply voltage, the communication state and the capacitor voltage-sharing of the voltage source converter valve submodule are determined to be normal, and when the number of bypass submodules of the voltage source converter valve is less than the preset redundant number, the voltage at two ends of a bridge arm of the tested voltage source converter valve, a valve section, a valve tower or a valve hall is controlled to rise to the rated voltage, the preset time length is kept, and the voltage withstand test of the converter valve is completed within the preset time length.
In the embodiment of the invention, after the withstand voltage test is completed, unlocking the converter valve of the voltage source to be tested, and performing the electrical performance test on the converter valve of the voltage source to be tested comprises the following steps:
and controlling the isolating switch to disconnect an external test direct-current power supply, unlocking the converter valve of the tested voltage source to perform passive unlocking, and performing electrical performance test detection on the converter valve of the tested voltage source according to the output waveform of the converter valve of the tested voltage source.
In the embodiment of the invention, the passive unlocking of the converter valve of the measured voltage source comprises the following steps:
according to a preset fixed modulation ratio, passively unlocking a converter valve of a voltage source to be measured in preset different time lengths; or
And according to the preset fixed time length, carrying out passive unlocking on the converter valve of the voltage source to be measured by preset different modulation ratios.
In the embodiment of the invention, after the withstand voltage test is completed, unlocking the converter valve of the voltage source to be tested, and performing the electrical performance test on the converter valve of the voltage source to be tested comprises the following steps:
and carrying out active unlocking on the converter valve of the voltage source to be tested, and carrying out electrical performance test detection on the converter valve of the voltage source to be tested according to the output waveform of the converter valve of the voltage source to be tested.
In the embodiment of the invention, the active unlocking of the converter valve of the voltage source to be measured comprises the following steps:
according to a preset fixed modulation ratio, carrying out active unlocking on the converter valve of the voltage source to be measured in preset different time lengths; or
And carrying out active unlocking on the converter valve of the voltage source to be measured according to preset fixed time length and preset different modulation ratios.
On the other hand, the invention also provides a flexible direct-current transmission voltage source converter valve test power supply device, wherein the power supply device is used for outputting a direct-current power supply and providing the external test direct-current power supply; the test power supply comprises: the system comprises an incoming line switch protection circuit, a voltage regulating device and a step-up transformer;
one end of the incoming line switch protection circuit is connected to one end of the voltage regulating device, the other end of the incoming line switch protection circuit is connected with an external alternating current power supply, and the incoming line switch protection circuit realizes connection and disconnection of an external alternating current source and the voltage regulating device;
the other end of the voltage regulating device is connected to the primary side of the boosting transformer and is used for regulating the voltage of an external alternating current power supply connected through the incoming line switch protection circuit;
the first end of the secondary side of the boosting transformer is grounded, and the second end of the secondary side of the boosting transformer is used for outputting a direct-current power supply required by the charging and unlocking test.
According to the flexible direct-current transmission voltage source converter valve test method and the test power supply, the positive electrode, ground or negative electrode connecting end of a voltage source converter valve to be tested is connected to an external test direct-current power supply through the control isolating switch; controlling the external test direct-current power supply to boost the voltage to charge the capacitor of the tested voltage source converter valve, and testing the starting voltage of the energy taking power supply of the tested voltage source converter valve; after the capacitor of the converter valve of the voltage source to be tested is charged to the rated voltage, a withstand voltage test is carried out on the converter valve of the voltage source to be tested; after the withstand voltage test is finished, unlocking the converter valve of the voltage source to be tested, and carrying out an electrical performance test on the converter valve of the voltage source to be tested; and after the electrical performance test is finished, locking the converter valve of the voltage source to be tested, and carrying out energy taking power supply locking test on the converter valve of the voltage source to be tested. The method comprises the steps of controlling diodes of submodules of a converter valve to form a rectifying circuit by controlling the access and boosting processes of an external direct-current power supply, completing a charging step, and completing the energy-taking power supply starting voltage test, the submodule withstand voltage test, the IGBT switching-on and switching-off test, the bypass switch protection action test, the energy-taking power supply blocking voltage test, the submodule capacitor test and the submodule discharging resistance test of the whole converter station, the converter, the valve tower and the valve assembly submodule at one time.
In order to make the aforementioned and other objects, features and advantages of the invention comprehensible, preferred embodiments accompanied with figures are described in detail below.
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, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.
FIG. 1 is a flow chart of a converter valve testing method for a flexible direct current transmission voltage source provided by the invention;
fig. 2 is a schematic diagram of a connection of a dc voltage-increasing test power supply of a pseudo bipolar converter according to an embodiment of the present invention;
fig. 3 is a schematic diagram of the connection of a dc power supply of a true bipolar converter provided in the embodiment of the present invention;
FIG. 4 is a schematic diagram of the positive connection of the DC voltage-increasing test power supply of the unipolar converter provided in the embodiment of the present invention;
FIG. 5 is a schematic diagram of the negative connection of the DC voltage-increasing test power supply of the unipolar converter provided in the embodiment of the present invention;
fig. 6 is a schematic diagram of the positive dc power connection of a true bipolar converter provided in the embodiment of the present invention;
fig. 7 is a schematic diagram of the negative dc power connection of a true bipolar converter according to an embodiment of the present invention;
fig. 8 is a schematic view of an unlock waveform of a pseudo bipolar converter in an embodiment of the present invention;
fig. 9 is a schematic view of an unlocking waveform of a true bipolar converter in the embodiment of the present invention;
FIG. 10 is a schematic diagram of a true bipolar (pseudo bipolar) marine flexible DC power transmission converter valve DC charging apparatus;
FIG. 11 is a three-phase schematic diagram of a true bipolar (pseudo bipolar) marine flexible DC power transmission converter valve DC charging apparatus;
FIG. 12 is a single-phase schematic diagram of a positive polarity DC transmission converter valve DC charging device;
FIG. 13 is a single-phase schematic diagram of a negative-polarity DC transmission converter valve DC charging device;
FIG. 14 is a three-phase schematic diagram of a positive polarity DC power transmission converter valve DC charging device;
FIG. 15 is a three-phase schematic diagram of a negative-polarity DC transmission converter valve DC charging device.
Detailed Description
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 only a part of the embodiments of the present invention, and not all of the embodiments. 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.
Offshore wind power flexible direct current transmission engineering is similar to onshore flexible direct current transmission, and an offshore platform does not have an alternating current power supply point and load of an onshore converter station, so that the offshore wind power flexible direct current transmission engineering and the onshore flexible direct current transmission engineering face different engineering practical problems. The debugging of the offshore converter station is mainly divided into two stages of debugging of a station system at a wharf and debugging of an end-to-end system at sea, wherein the debugging of the station system is the basis and guarantee of the end-to-end system debugging. Only sufficient and perfect station system tests can ensure the safety of equipment and the smooth operation of system debugging. According to the existing debugging experience, during the debugging, the converter valve is generally charged and unlocked through an alternating current system, but the converter valve is charged and unlocked from alternating current, so that a plurality of problems are faced in offshore flexible and straight engineering, and the main problems are as follows:
1. large power supply capacity is required and the converter valves are large (in the order of about 1000 MVA) and require very high system strength and power supply capacity during dock commissioning. And calculating the transient power of the switching converter transformer when the converter valve is charged and unlocked from the alternating current to account for 5% of rated power, wherein the power supply capacity required by the alternating current system is 50MVA and is about the main transformer capacity of 1-2 transformer substations of 110 kV. In addition, under the condition that the system strength is weak, the stability problems such as system oscillation exist, and the safety of the converter valve and equipment is threatened.
2. Before the modular voltage source converter valve needs to be added with the charging resistor, the voltage of the capacitor is zero, and the capacitor is approximately short-circuited. Without a charging resistor, a very large charging current would be generated, resulting in damage to the converter valves. Therefore, it is necessary to increase a charging resistance to limit an overcurrent during charging. If the converter valve is charged through alternating current, the capacity of a charging resistor is about 5MVA, the cost of the resistor is high, and the cost is about 200 ten thousand; the manufacturing period of the resistor is long, the resistor needs to be specially customized, and the time is about 4-6 months; the resistance commonality is poor, according to every engineering concrete parameter, needs different charging resistance.
3. The grounding points of offshore wind power flexible and straight projects which need temporary grounding devices are all arranged on the land, and the offshore converter station has no grounding point. The offshore converter station needs to be additionally provided with a temporary grounding device during onshore debugging. The grounding mode can be adopted, the direct current resistance is mainly used for dividing voltage and the grounding reactance is mainly used for dividing voltage, and the cost of the direct current resistance and the grounding reactance is about 100 ten thousand. In addition, the ground impedance of the temporary grounding device is difficult to meet debugging requirements (less than 0.5 ohm).
4. The normal operation of the offshore converter station is different from the actual system operation mode, and the converter valve is charged and unlocked through the direct current side. If charging and unlocking are performed from the AC side, the debugging and normal operation modes are different. If charging and unlocking are carried out from the alternating current side, corresponding tests are required to be supplemented during offshore commissioning.
For the above reasons, the debugging mode of the onshore converter station is continuously adopted, and the mode of charging and unlocking the converter valve through the alternating current system is not economical and is not feasible. Finding a power supply and a method suitable for debugging the offshore flexible-direct converter station becomes the biggest difficult problem restricting the offshore flexible-direct debugging, and a new debugging technology and equipment must be found. Therefore, the system is charged and unlocked from the direct current side, so that the problems of power supply capacity, high-power charging resistance, temporary grounding devices, operation modes and the like are solved.
In view of this, the present invention provides a method for testing a converter valve of a flexible direct current transmission voltage source, as shown in fig. 1, the method of the present invention includes:
step S101, connecting the positive electrode, the ground or the negative electrode connecting end of the converter valve of the voltage source to be tested to an external test direct current power supply by controlling an isolating switch;
step S102, controlling the external test direct-current power supply to boost the voltage to charge the capacitor of the tested voltage source converter valve, and carrying out energy-taking power supply starting voltage test on the tested voltage source converter valve;
step S103, after the capacitor of the voltage source converter valve to be tested is charged to rated voltage, a voltage withstanding test is carried out on the voltage source converter valve to be tested;
step S104, after the withstand voltage test is finished, unlocking the converter valve of the voltage source to be tested, and carrying out an electrical performance test on the converter valve of the voltage source to be tested;
and S105, after the electrical performance test is finished, locking the converter valve of the voltage source to be tested, and carrying out energy taking power supply locking test on the converter valve of the voltage source to be tested.
The technical solutions of the present invention are described in detail below with reference to specific embodiments, and before describing the embodiments of the present invention, terms related to technical solutions provided by the embodiments of the present invention are described below.
A voltage source converter valve is mainly a modular multilevel converter valve, namely an MMC (MMC, modular multilevel) converter valve is divided into a converter valve power module (hereinafter referred to as a submodule), a valve section, a valve layer and a valve tower structure, wherein generally 4-6 submodules form 1 valve section, 4-6 valve sections form 1 valve layer, 4-5 valve layers form 1 valve tower, and 1 bridge arm of a valve hall in a converter station generally comprises 2 valve towers.
Fig. 2 shows a unipolar voltage source converter valve topology and fig. 3 shows a true bipolar voltage source converter valve topology. The converter valve submodule is the minimum unit of the converter valve, the submodule consisting of a power electronic element IGBT and an anti-parallel diode thereof is the core element of the converter valve, the electrical performance of the submodule directly influences the overall function of the converter valve, and the converter valve is easily influenced by complex transportation environments such as vibration, falling, high and low temperature, humidity and the like in the process of transporting the converter valve to the site.
In the prior art, the performance test of the sub-modules is realized by charging the sub-modules of the converter valve through the power supply of the rectifier module, a method for detecting the overall performance of the converter valve is lacked, and various functions such as connection, installation, communication and the like among the sub-modules cannot be judged to be normal effectively.
Therefore, in view of the above technical problems, the present invention provides a charging scheme for realizing capacitor charging of a sub-module of an MMC converter valve by using an external dc power supply to a diode rectifying circuit of the sub-module, which simplifies the charging circuit, reduces the requirements of charging equipment, improves the operability of the charging step, and has a wide application range. The converter, the converter valve section and the converter valve assembly test based on the charging scheme are used for checking the internal electrical performance of the converter valve and the submodule, the complete test process can complete test items including the converter, the converter valve section and the converter valve assembly submodule energy-taking power supply starting voltage test, the submodule withstand voltage test, the IGBT (insulated gate bipolar translator) switching-on and switching-off test, the bypass switch protection action test and the energy-taking power supply locking test, the submodule direct-current side capacitor and the discharging resistor voltage test, the converter valve performance check is complete, the test operation is flexible and simple, and the converter valve section test based on the charging scheme can be popularized and applied to single-pole, pseudo-bipolar and true-bipolar converter valve performance tests.
The following describes the scheme for detecting the electrical performance of the converter valve in detail.
The embodiment of the invention provides a method for testing the direct-current side charging and unlocking of a converter valve of a flexible direct-current transmission voltage source, which is used for improving the efficiency and reliability of the detection of the internal electrical performance of a converter and a converter valve submodule.
(1) The wiring and corresponding electrical operation during the test was as follows:
in the test wiring process before the test, the electric connection between the converter valve and the outside is firstly disconnected, and a sufficient safety distance is kept.
And then connecting a test power line into the converter valve, and respectively connecting the anode, the ground and the cathode of the test power source to the anode, the ground and the cathode of the voltage source converter valve according to the topological structure of the flexible direct current transmission system.
And then disconnecting the corresponding grounding knife of the converter valve.
And finally, combining the current into a corresponding isolation knife of the converter valve to enable an external direct current power supply and the converter valve to form a loop.
(2) The test power supply and the converter valve are connected as follows:
for a pseudo-bipolar flexible dc transmission system, as shown in fig. 2, the positive pole, ground and negative pole of the test power source are connected to the positive pole, ground and negative pole of the voltage source converter valve, respectively.
For a true bipolar flexible dc transmission system, as shown in fig. 3, bipolar simultaneous tests are performed, where the positive, ground and negative poles of the test power source are connected to the positive, ground and negative poles of the voltage source converter valve, respectively.
For a single-pole flexible direct current transmission system, when a positive pole converter is used, the positive pole and the ground of a test power supply are respectively connected with the positive pole and the ground of a voltage source converter valve, and a negative pole direct current power supply is suspended and is not connected, as shown in fig. 4.
For a single-pole flexible direct current transmission system, when a negative pole converter is used, a negative pole and a ground of a test power supply are respectively connected with a negative pole and a ground of a voltage source converter valve, and a positive pole direct current power supply is suspended and is not connected, as shown in fig. 5.
The true bipolar flexible DC transmission converter is tested separately in units of poles.
In the true bipolar flexible direct current transmission converter, during the positive pole test, the positive pole and the ground of a test power supply are respectively connected with the positive pole and the ground of a voltage source converter valve, and a negative pole direct current power supply is suspended and is not connected, as shown in figure 6.
During the negative pole test of the true bipolar flexible direct current transmission converter, the negative pole and the ground of a test power supply are respectively connected with the negative pole and the ground of a voltage source converter valve, and a positive direct current power supply is suspended and not connected, as shown in figure 7.
(3) After the test power supply is connected, the converter valve is cooled by water, and the control protection device normally operates, the direct-current power supply device pressurizes the converter valve.
(4) The pressurizing process can adopt two modes of staged pressurizing and gradual pressurizing.
Controlling an external direct current power supply to slowly boost the voltage to the minimum energy-taking power supply of the submodules in a step-by-step pressurizing mode, checking that the state of each submodule is normal, and continuing the test if the number of abnormal modules does not exceed a redundancy value; after the direct current voltage is added to the rated voltage, the running voltage is checked; and after the inspection is finished, the conditions of the converter valve unlocking test are met.
In a step-by-step pressurization mode, an external direct-current power supply is controlled to slowly boost the rated voltage of the converter valve, and submodule state inspection and running voltage inspection are carried out through a converter valve pole control and valve control monitoring background; and after the inspection is finished, the conditions of the converter valve unlocking test are met.
In the embodiment of the invention, the sub-module state check and the operation voltage check can be realized through the pole control and valve control monitoring system of the converter valve of the flexible direct-current transmission voltage source, and a person skilled in the art can clearly know how to realize the sub-module state check and the operation voltage check by using the pole control and valve control monitoring system, and details are not repeated here.
(5) In the charging process, according to the functions of monitoring the communication state, the energy-obtaining power supply working state, the direct-current voltage detection voltage of each submodule and the like of the submodule of the converter station and the converter valve, when the difference value of the direct-current voltage detection of each submodule and the preset starting voltage is smaller than a first preset voltage value, the energy-obtaining power supply starting voltage test of each submodule is completed according to the detected energy-obtaining power supply voltage, the communication state and the submodule capacitor voltage-sharing condition of each submodule.
(6) After monitoring that the energy-taking power supply voltage of each submodule is normal, the communication state is normal and the capacitance voltage-sharing is normal, and the number of bypass submodules is less than the redundancy number, the converter valve and submodule voltage withstand test controls the voltage at two ends of a tested voltage source converter, a converter valve, a valve section, a valve tower or a valve hall bridge arm to rise to the rated voltage, keeps the preset time length, and completes the converter valve and submodule voltage withstand test within the preset time length.
(7) The method for testing the electrical performance of the voltage source converter valve can be divided into passive unlocking and active unlocking according to the existence of a direct current power supply, and the passive unlocking is firstly carried out in order to ensure the safety of the converter valve and the direct current power supply.
The converter valve isolating switch or the direct-current power supply can be closed, the direct-current power supply is withdrawn, and the passive unlocking of the converter valve is carried out;
the direct current power supply can be kept off, and the active unlocking of the converter valve can be carried out by the direct current power supply.
And (7.1) in order to ensure the correct control and protection functions and the safety of the converter valve, the converter valve can be unlocked at different modulation ratios and different time lengths under the passive unlocking condition.
The modulation ratio may be increased stepwise with a fixed length of unlocking time until the modulation ratio is 1;
the unlocking time can be increased step by step with a fixed modulation ratio until a long unlocking time.
To ensure the safety of the converter valve, the unlocking is started with a lower modulation ratio and a shorter time, and then the modulation ratio and the unlocking time are gradually increased.
In a passive unlocking condition, the converter valves may be unlocked with a fixed modulation ratio for different lengths of time.
Firstly, unlocking a converter valve for 20ms of one cycle, and checking whether the output waveform of the alternating voltage output by the converter valve is consistent with the output waveform of a control protector;
gradually increasing the unlocking time of the converter valve, and if the converter valve is unlocked for 100ms, checking whether the output waveform of the alternating voltage output by the converter valve is consistent with the control protection issuing waveform;
further increasing the unlocking time of the converter valve, if the converter valve is unlocked for 500ms, checking whether the output waveform of the alternating voltage output by the converter valve is consistent with the control protection issuing waveform;
after the control protection function is verified to be correct, the converter valve can be unlocked for a long time.
In the passive unlocking condition, the converter valves can be unlocked with different modulation ratios with the unlocking time.
Firstly, unlocking the converter valve for a fixed time at a lower modulation ratio, such as 0.5, and checking whether the output waveform of the alternating voltage output by the converter valve is consistent with the control and protection issuing waveform;
when the modulation ratio is increased, if the modulation ratio is 0.8, the converter valve is unlocked for a fixed time, and whether the output waveform of the alternating voltage output by the converter valve is consistent with the control protection issuing waveform or not is checked;
increasing the modulation ratio to 1, unlocking the converter valve for fixed time, and checking whether the output waveform of the alternating voltage output by the converter valve is consistent with the output waveform of the control protector;
after the control protection function is verified to be correct, the converter valve can be unlocked for a long time.
(7.2) in the active unlocking condition, the converter valves can be unlocked at different modulation ratios and different time lengths.
The modulation ratio may be increased stepwise with a fixed length of unlocking time until the modulation ratio is 1;
the unlocking time can be increased step by step with a fixed modulation ratio until a long unlocking time.
In the active unlocking condition, the converter valves can be unlocked with a fixed modulation ratio for different lengths of time.
Firstly, unlocking a converter valve for 20ms of one cycle, and checking whether the output waveform of the alternating voltage output by the converter valve is consistent with the output waveform of a control protector;
gradually increasing the unlocking time of the converter valve, and if the converter valve is unlocked for 100ms, checking whether the output waveform of the alternating voltage output by the converter valve is consistent with the control protection issuing waveform;
further increasing the unlocking time of the converter valve, if the converter valve is unlocked for 500ms, checking whether the output waveform of the alternating voltage output by the converter valve is consistent with the control protection issuing waveform;
after the control protection function is verified to be correct, the converter valve can be unlocked for a long time.
In the active unlocking condition, the converter valves can be unlocked with different modulation ratios with the unlocking time.
Firstly, unlocking the converter valve for a fixed time at a lower modulation ratio, such as 0.5, and checking whether the output waveform of the alternating voltage output by the converter valve is consistent with the control and protection issuing waveform;
when the modulation ratio is increased, if the modulation ratio is 0.8, the converter valve is unlocked for a fixed time, and whether the output waveform of the alternating voltage output by the converter valve is consistent with the control protection issuing waveform or not is checked;
increasing the modulation ratio to 1, unlocking the converter valve for fixed time, and checking whether the output waveform of the alternating voltage output by the converter valve is consistent with the output waveform of the control protector;
after the control protection function is verified to be correct, the converter valve can be unlocked for a long time.
The pseudo bipolar converter valve unlock waveform is shown in fig. 8 and the true bipolar converter valve unlock waveform is shown in fig. 9.
(8) In the process of the pressurization test, after the voltage source converter valve is charged to a certain stage, the voltage source converter valve enters an active charging stage, so that the number of the converter valves which are put into the sub-modules is suddenly reduced by half, and in order to reduce the uncontrollable charging of the converter valves to the active charging conversion process, the direct-current power supply is over-current caused by the sudden change of the number of the sub-modules, or the required direct-current power supply capacity is overlarge. Namely, when the voltage source converter valve is charged from uncontrolled to active, the number of each bridge arm submodule is adjusted according to a preset converter valve control adjustment strategy, and an overcurrent protection fixed value of an external direct current power supply is adjusted.
Specifically, in an embodiment of the present invention, the following measures are taken as a preset converter valve control adjustment strategy, so as to adjust the number of sub-modules of each bridge arm and adjust an overcurrent protection fixed value of an external dc power supply, and the specific measures include:
and adjusting the exit rate of the sub-modules in a valve control strategy of the converter valve, and gradually exiting the sub-modules from uncontrolled charging to active charging to avoid sudden change of the number of the sub-modules. And if the number of the submodules of each bridge arm is 432, the next time, 431 submodules are obtained until the number of the submodules is reduced to the required number.
And the valve control strategy of the converter valve is adjusted, so that the speed of exiting the sub-modules is reduced while the sudden change of the number of the sub-modules is avoided. And if the number of the submodules of each bridge arm is 432, the next time, 431 submodules are obtained until the number of the submodules is reduced to the required number.
And adjusting the overcurrent protection fixed value of the external direct-current power supply, specifically adjusting a section of overcurrent protection fixed value according to the converter valve submodule parameters.
(9) And after the converter valve is locked, testing the bypass capacitance parameter and the discharge resistance of the submodule, testing the switch protection action function and locking the submodule energy-taking power supply. And the converter valve submodule calculates the direct current capacitor and the direct current side resistor of the submodule according to the voltage discharge speed of the direct current capacitor.
Compared with the scheme of realizing the test of the electric performance of the converter valve and the sub-module by charging the sub-module of the converter valve through a direct current power supply in the prior art, the technical scheme provided by the embodiment of the invention utilizes the diodes of the sub-module of the converter valve to form a rectifying circuit to finish the charging step, namely as shown in figure 2, the diodes and the capacitors on the sub-modules form a circuit to finish the test of the starting voltage of the energy-taking power supply of the sub-modules of the whole converter station, the converter, the valve tower and the valve assembly, the voltage withstanding test of the sub-modules, the on-off test of the IGBT, the protection action test of the bypass switch, the blocking voltage of the energy-taking power supply, the capacitors of the sub-modules and the discharge resistance test of the sub-modules at one time, and can fully examine the electric performance and the parameters of the sub-modules of the converter valve and the sub-modules. The technical scheme provided by the embodiment of the invention can be used for detecting the performance detection and test of the converter valve under the condition that an island converter station, an offshore converter station and an onshore converter station have no alternating current system power supply, and ensuring that the converter valve is safely and reliably put into operation.
In addition, the invention also provides a flexible direct-current transmission voltage source converter valve test power supply device, wherein the power supply device is used for outputting a direct-current power supply and providing an external test direct-current power supply required by the test method; the test power supply comprises: the system comprises an incoming line switch protection circuit, a voltage regulating device and a step-up transformer;
one end of the incoming line switch protection circuit is connected to one end of the voltage regulating device, the other end of the incoming line switch protection circuit is connected with an external alternating current power supply, and the incoming line switch protection circuit realizes connection and disconnection of an external alternating current source and the voltage regulating device;
the other end of the voltage regulating device is connected to the primary side of the boosting transformer and is used for regulating the voltage of an external alternating current power supply connected through the incoming line switch protection circuit;
the first end of the secondary side of the boosting transformer is grounded, and the second end of the secondary side of the boosting transformer is used for outputting a direct-current power supply required by the charging and unlocking test.
Fig. 10 is a schematic diagram of a dc charging device for a flexible dc transmission converter valve according to an embodiment of the present invention.
The first end of the incoming line switch protection cabinet is connected with an external alternating current power supply and used for connecting the external alternating current power supply. And the connection and disconnection of the transformer and the alternating current power supply are realized.
In the embodiment of the invention, the incoming line switch cabinet comprises a current-limiting resistor and a closing resistor structure, wherein the current-limiting resistor is used for reducing the excitation inrush current of a transformer; the closing resistor structure is used for controlling the connection and disconnection of the current-limiting resistor.
Specifically, as shown in fig. 10, in this embodiment, the incoming line switch cabinet is formed by connecting two branches, namely a current limiting branch and a switch branch in parallel, where the current limiting branch is formed by a current limiting resistor R1And switch S2Are connected in series, the switch branch being a switch S1Composition, in a specific incorporation sequence of operations, in the assurance switch S1And S2In case of disconnection, S is incorporated2A switch; after a period of time, S is incorporated1Switch, separate S2And the switch and the incoming line switch cabinet are operated. When separated, directly separate S1And (4) switching.
The first end of the regulating transformer is connected with the alternating current power supply through the second end of the incoming line switch cabinet, and the regulating transformer is used for regulating the voltage of an external alternating current power supply, reducing the impact current and the capacity of the whole set of equipment and improving the safety of the equipment.
In the embodiment of the invention, the voltage regulating transformer is a single-phase power frequency transformer or a three-phase power frequency transformer.
When the external power supply of the test device adopts a three-phase power supply, a three-phase transformer is selected. When the external power supply of the test device adopts a single-phase power supply, a single-phase transformer is selected.
When the device is used for testing a true bipolar or a false bipolar voltage source converter valve, the boosting transformers of the positive and negative polarities of the device can share one group of transformers, 2 groups of transformers can also be used, and the positive and negative polarities respectively use one group of regulating transformers. Fig. 2 is a schematic diagram of a true bipolar (pseudo bipolar) marine flexible direct-current transmission converter valve direct-current charging device adopting a three-phase power supply and a three-phase circuit, and in the embodiment shown in fig. 11, two groups of step-up transformers are adopted.
The step-up transformer is a single-phase power frequency transformer or a three-phase power frequency transformer, and can be a semi-insulating transformer.
The primary side of the boosting transformer is connected with the alternating current power supply at the second end of the regulating transformer and used for boosting the low-voltage alternating current power supply of the regulating transformer to required alternating voltage, and the first end of the secondary side of the boosting transformer is grounded;
AC current limiting resistor R2AC current limiting resistor R2The first end of the booster transformer is electrically connected with an alternating current power supply through the second end of the booster transformer and is used for limiting current in the boosting process and protecting equipment when the equipment body breaks down;
voltage-multiplying capacitorC 1Voltage multiplying capacitorC 1First terminal and AC current limiting resistorR 2The second end of the first diode is connected with the first end of the second diode, and is used for realizing voltage doubling;
rectifier diodeD 1Rectifier diodeD 1First terminal and voltage-multiplying capacitorC 1Second terminal connected to a rectifier diodeD 1Is connected to ground, a rectifier diodeD 1And voltage-multiplying capacitorC 1Together, achieving a one-time boost of the rectified voltage;
rectifier diodeD 2A first terminal thereof and a voltage-multiplying capacitorC 1The second end is connected to realize the unidirectional flow of current and avoid the reverse charging of the converter valve power supply to the rectifying device;
filter capacitorC 2Filter capacitorC 2First terminal and rectifier diodeD 2The second end of the filter is connected to filter the uncontrollable rectified voltage, so that the output voltage is smoother;
a voltage divider composed of resistors for dividing voltageFirst end of rectifier and rectifier diodeD 2The second end of the voltage divider is connected with the ground and used for measuring the output direct-current voltage; or the voltage divider is not configured, and the voltage is read by using the converter valve measuring device of the flexible direct-current transmission voltage source;
DC current-limiting resistorR 2DC current-limiting resistorR 2First terminal and rectifier diodeD 2A second terminal connected to a current limiting resistorR 2The second end of the converter valve is connected to a tested flexible direct current transmission voltage source converter valve and used for limiting current in the boosting process and protecting equipment when the equipment body and a tested object have faults;
discharge device and discharge switchS 3Discharge device and discharge switch in normal operationS 3In the off state; after the test is finished, the AC power switch is switched offS 1Then, the discharge switch is closedS 3Discharge switch pair DC filter capacitorC 2And (4) discharging.
A controller for controlling the switch S1、S2And S3The opening and closing and the locking of the voltage regulating transformer.
And the protection device is used for protecting related overcurrent and overvoltage of the device and avoiding the influence on the system caused by equipment failure.
The device for the direct-current charging and unlocking test of the converter valve of the flexible direct-current transmission voltage source can be applied to the tests of the converter valves of the flexible direct-current transmission true bipolar and false bipolar voltage sources and the converter valves of the unipolar voltage source, the high-voltage direct-current power output by the device is connected with the corresponding polarity of the converter valves, and the equipment ground is connected with the flexible direct-current system ground.
The testing device provided by the embodiment of the invention is applied to the test of the converter valve with the single-pole voltage source, the positive pole or the negative pole of the high-voltage direct-current power source output by the device is connected with the corresponding polarity of the converter valve, and the equipment ground is connected with the flexible direct system ground.
As shown in fig. 12, for a single-phase schematic diagram of the test apparatus provided in the embodiment of the present invention as a positive-polarity flexible dc transmission converter valve dc charging apparatus, when the apparatus is applied to a positive-polarity converter valve test, the rectifier connection is specifically as follows:
rectifier diode D1Rectifier diode D1Cathode and voltage-multiplying capacitor C1Second terminal connected to a rectifier diode D1Anode connected to ground, rectifying diode D1And voltage-multiplying capacitor C1Together, achieving a one-time boost of the rectified voltage;
rectifier diode D2Rectifier diode D2Anode and voltage-multiplying capacitor C1The second end is connected to realize the unidirectional flow of current and avoid the reverse charging of the converter valve power supply to the rectifying device;
filter capacitor C2Filter capacitor C2First terminal and rectifier diode D2The cathode is connected, and the uncontrollable rectified voltage is filtered, so that the output voltage is smoother;
a voltage divider composed of a resistor, a first end of the voltage divider and a rectifying diode D2The second end of the voltage divider is connected with the ground and is used for measuring output direct-current voltage; or the voltage divider is not configured, and the voltage is read by using the converter valve measuring device of the flexible direct-current transmission voltage source;
DC current limiting resistor R3D.C. current limiting resistor R3First terminal and rectifier diode D2Cathode connected, current limiting resistor R3The second end of the converter valve is connected to a tested flexible direct current transmission voltage source converter valve and used for limiting current in the boosting process and protecting equipment when the equipment body and a tested object have faults;
as shown in fig. 13, which is a single-phase schematic diagram of the testing apparatus of the present invention as a negative-polarity flexible dc transmission converter valve dc charging apparatus, when the apparatus is applied to a negative converter valve test, the rectifier connection is:
rectifier diode D1Rectifier diode D1Anode and voltage-multiplying capacitor C1Second terminal connected to a rectifier diode D1The cathode is connected to ground, rectifying diode D1And voltage-multiplying capacitor C1Together, achieving a one-time boost of the rectified voltage;
rectifier diode D2Rectifier diode D2Cathode and voltage-multiplying capacitor C1The second end is connected to realize the unidirectional flow of current and avoid the reverse charging of the converter valve power supply to the rectifying device;
filter capacitor C2Filter capacitor C2First terminal and rectifier diode D2The anode is connected, and the uncontrollable rectified voltage is filtered, so that the output voltage is smoother;
a voltage divider composed of a resistor with a first end connected with a rectifying diode D2The second end of the anode is connected with the ground and used for measuring output direct-current voltage; or the voltage divider is not configured, and the voltage is read by using the converter valve measuring device of the flexible direct-current transmission voltage source;
DC current limiting resistor R3First terminal and rectifier diode D2Anode connected, current limiting resistor R3And the second end of the converter valve is connected to the tested flexible direct current transmission voltage source converter valve and used for limiting the current in the boosting process and protecting the equipment when the equipment body and the tested object have faults.
The device of the embodiment is applied to a true bipolar or pseudo-pole voltage source converter valve test, the positive pole and the negative pole of a high-voltage direct current power supply output by the device are simultaneously connected with the corresponding polarities of the converter valve, and the equipment ground is connected with the flexible direct current system ground.
In the embodiment of the present invention, the apparatus further includes: AC current limiting resistor R2Capacitor C1Rectifier diode D1And a rectifier diode D2(ii) a I.e. by the capacitor C1Rectifier diode D1And a rectifier diode D2The formed rectifier circuit rectifies the voltage output by the high-voltage side of the transformer to realize the boost of the direct-current voltage without impulse current, and can meet the direct-current side charging and unlocking test of the converter valve through optimized parameters of the transformer, the rectifier and the capacitor2The output is rectified by a rectifier ground circuit.
In this embodiment, the second end of the secondary side of the step-up transformer is connected to the ac current limiting resistor R2The first terminal of (1), the alternating current limiting resistor R2Through a capacitor C1And a rectifier diode D2Is connected to the first terminal of the rectifier diode D2Is connected to an external device under test to output a voltage required for a charging and unlocking test, and the rectifier diode D1Is connected to said capacitor C1And a rectifier diode D2Between, the rectifier diode D1The second terminal of (a) is grounded.
In the embodiment of the invention, the testing device is used for a rectifying circuit when a positive polarity converter valve experiment is carried out;
the rectifier diode D1The first terminal of (D) is a cathode, and a rectifier diode D1The second end of (a) is an anode;
the rectifier diode D2The first terminal of (D) is an anode, and a rectifier diode D2The second end of (a) is a cathode.
In the embodiment of the invention, the device is used for a rectifying circuit when a negative polarity converter valve experiment is carried out;
the rectifier diode D1The first terminal of (D) is an anode, and a rectifier diode D1The second end of (a) is a cathode;
the rectifier diode D2The first terminal of (D) is a cathode, and a rectifier diode D2The second end of (a) is an anode.
As shown in fig. 12, the positive power rectifier is connected as follows:
rectifier diode D1Rectifier diode D1Cathode and voltage-multiplying capacitor C1Second terminal connected to a rectifier diode D1Anode connected to ground, rectifying diode D1And voltage-multiplying capacitor C1Together, achieving a one-time boost of the rectified voltage;
rectifier diode D2Rectifier diode D2Anode and voltage-multiplying capacitor C1The second end is connected to realize the unidirectional flow of current and avoid the reverse charging of the converter valve power supply to the rectifying device;
filter capacitor C2Filter capacitor C2First terminal and rectifier diode D2The cathode is connected, and the uncontrollable rectified voltage is filtered, so that the output voltage is smoother;
voltage divider of voltage-dividing group by resistorsFirst end of the voltage divider and the rectifier diode D2The second end of the cathode is connected, and the second end of the voltage divider is connected with the ground and used for measuring output direct-current voltage; or the voltage divider is not configured, and the voltage is read by using the converter valve measuring device of the flexible direct-current transmission voltage source;
DC current limiting resistor R2D.C. current limiting resistor R2First terminal and rectifier diode D2Cathode connected, current limiting resistor R2The second end of the converter valve is connected to a tested flexible direct current transmission voltage source converter valve and used for limiting current in the boosting process and protecting equipment when the equipment body and a tested object have faults;
as shown in fig. 14, the negative power rectifier is connected as follows:
rectifier diode D1Rectifier diode D1Anode and voltage-multiplying capacitor C1Second terminal connected to a rectifier diode D1The cathode is connected to ground, rectifying diode D1And voltage-multiplying capacitor C1Together, achieving a one-time boost of the rectified voltage;
rectifier diode D2Rectifier diode D2Cathode and voltage-multiplying capacitor C1The second end is connected to realize the unidirectional flow of current and avoid the reverse charging of the converter valve power supply to the rectifying device;
filter capacitor C2Filter capacitor C2First terminal and rectifier diode D2The anode is connected, and the uncontrollable rectified voltage is filtered, so that the output voltage is smoother;
a voltage divider composed of a resistor with a first end connected with a rectifying diode D2The anode is connected, and the second end of the anode is connected with the ground and used for measuring the output direct-current voltage; or the voltage divider is not configured, and the voltage is read by using the converter valve measuring device of the flexible direct-current transmission voltage source;
DC current limiting resistor R2D.C. current limiting resistor R2First terminal and rectifier diode D2A second end of the anode is connected with a current limiting resistor R2And the second end of the converter valve is connected to the tested flexible direct current transmission voltage source converter valve and used for limiting the current in the boosting process and protecting the equipment when the equipment body and the tested object have faults.
Test power supply, voltage regulating transformer, step-up transformer and AC current limiting resistor R2Voltage-multiplying capacitor C1Rectifier diode D1The circuit can be a single-phase circuit or a three-phase circuit.
The three-phase circuit is composed of three identical regulating transformers, step-up transformer and AC current-limiting resistor R2Voltage-multiplying capacitor C1Rectifier diode D1Rectifier diode D2And a unit is formed, and three units are respectively connected into the A, B and C phases, so that voltage-multiplying rectification of a power supply is realized. The three units are connected in parallel at a rectifier diode D2 and then connected with a filter capacitor C2And the current limiting resistor. Fig. 14 is a three-phase schematic diagram of the dc charging device for the positive-polarity flexible dc power transmission converter valve in the embodiment of the present invention, and fig. 15 is a three-phase schematic diagram of the dc charging device for the negative-polarity flexible dc power transmission converter valve in the embodiment of the present invention, where only a three-phase circuit single line diagram is illustrated, and for those skilled in the art, the connection relationship can be clearly obtained according to fig. 14 and fig. 15, and details are not repeated herein.
Before the controller is tested, the controller controls the device to regulate the transformer switch S1、S2Switch S of disconnecting and discharging device3Disconnecting; after the test is started, the voltage regulating transformer switch S of the controller control device is firstly controlled2Mixing in; then after a period of time, the controller controls the tap changer switch S of the device1Switching-in and switching-off voltage regulating transformer switch S2(ii) a And then the controller boosts an external alternating current power supply through a regulating voltage-regulating transformer, and outputs a loop formed by the rectified direct current power supply and the converter valve to a sub-module capacitor of a tested valve section, a valve tower or a valve hall bridge arm for charging. After completion of the test, S is divided1Switch, engaging in S3A switch for separating S after the device is discharged3And the test is finished.
The voltage regulating transformer in the embodiment can realize voltage regulation and frequency variation by adopting a mode based on a variable frequency power supply.
In the test device provided by the embodiment, in the charging process, the start voltage test of the converter valve and the energy taking power supply of the submodule and the withstand voltage test of the converter valve and the submodule are sequentially completed according to the detection voltage and current of the oscilloscope of the controller; after the voltage rises to the rated direct current voltage, starting an integral unlocking test of the converter valve, verifying the primary direct current withstand voltage and unlocking functions of the converter valve, checking secondary control logic, triggering, communication and the like, and preparing for live debugging of the flexible direct current transmission voltage source converter valve system.
The test device for the flexible direct-current transmission voltage source converter valve provided by the invention realizes zero start boosting of voltage through the boosting transformer, can meet the requirements of a converter valve direct-current side charging and unlocking test by selecting proper transformer, rectifier and capacitance parameters, can be applied to a test of a marine and onshore flexible direct-current transmission voltage source converter valve without a system power supply, and can comprehensively test the single body and the overall performance of the voltage source converter valve. In the embodiment of the invention, the step-up transformer can be realized by adopting a variable-frequency power supply.
The preferred embodiments of the present invention have been described above with reference to the accompanying drawings. The many features and advantages of the embodiments are apparent from the detailed specification, and thus, it is intended by the appended claims to cover all such features and advantages of the embodiments that fall within the true spirit and scope thereof. Further, since numerous modifications and changes will readily occur to those skilled in the art, it is not desired to limit the embodiments of the invention to the exact construction and operation illustrated and described, and accordingly, all suitable modifications and equivalents may be resorted to, falling within the scope thereof.
As will be appreciated by one skilled in the art, embodiments of the present invention may be provided as a method, system, or computer program product. Accordingly, the present invention may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Furthermore, the present invention 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 invention is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each flow and/or block of the flow diagrams and/or block diagrams, and combinations of flows and/or blocks in the flow diagrams and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
The principle and the implementation mode of the invention are explained by applying specific embodiments in the invention, and the description of the embodiments is only used for helping to understand the method and the core idea of the invention; meanwhile, for a person skilled in the art, according to the idea of the present invention, there may be variations in the specific embodiments and the application scope, and in summary, the content of the present specification should not be construed as a limitation to the present invention.

Claims (9)

1. A flexible direct-current transmission voltage source converter valve test method is characterized by comprising the following steps:
connecting the positive electrode, ground or negative electrode connecting end of the voltage source converter valve to be tested to an external test direct current power supply by controlling an isolating switch;
controlling the external test direct-current power supply to boost the voltage to charge the capacitor of the tested voltage source converter valve, and testing the starting voltage of the energy taking power supply of the tested voltage source converter valve;
after the capacitor of the converter valve of the voltage source to be tested is charged to the rated voltage, carrying out a withstand voltage test on the converter valve of the voltage source to be tested;
after the withstand voltage test is finished, unlocking the converter valve of the voltage source to be tested to perform an electrical performance test;
after the electrical performance test is finished, locking the converter valve of the voltage source to be tested, and carrying out energy taking power supply locking test on the converter valve of the voltage source to be tested;
the positive pole, the ground or the negative pole connecting end of the voltage source converter valve to be tested is connected to an external test direct current power supply by controlling the isolating switch, and the method comprises the following steps:
determining that the power transmission system is a true bipolar flexible direct current power transmission converter, wherein the anode, the ground and the cathode of the external test direct current power supply are respectively connected with the anode, the ground and the cathode connecting ends of the voltage source converter valve to be measured; or, during the positive pole test, the positive pole and the ground of the external test direct current power supply are respectively connected with the positive pole and the ground connecting end of the voltage source converter valve, and the negative pole direct current power supply is suspended and is not connected; during the negative pole test, the negative pole and the ground of the external test direct current power supply are respectively connected with the negative pole and ground connecting end of the voltage source converter valve, and the positive pole direct current power supply is suspended and is not connected;
determining that the power transmission system is a pseudo bipolar flexible direct current power transmission system, wherein the anode, the ground and the cathode of the external test direct current power supply are respectively connected with the anode, the ground and the cathode connecting ends of the voltage source converter valve to be measured;
determining that the power transmission system is a single-pole flexible direct-current power transmission system, when a current converter is a positive pole, the positive pole and the ground of the external test direct-current power supply are respectively connected with the positive pole and ground connecting ends of a voltage source converter valve to be measured, and a negative pole direct-current power supply is suspended and not connected; when the negative pole converter is used, the negative pole and the ground of the external test direct current power supply are respectively connected with the negative pole and ground connecting end of the voltage source converter valve to be tested, and the positive pole direct current power supply is suspended and is not connected.
2. The method for testing the converter valve of the flexible direct-current transmission voltage source according to claim 1, wherein the step of controlling the external test direct-current power supply to boost the voltage to charge the capacitor of the converter valve of the voltage source to be tested, and the step of testing the starting voltage of the energy-taking power supply for the converter valve of the voltage source to be tested comprises the following steps:
and controlling an external test direct-current power supply to boost the voltage to the minimum energy-taking voltage of the submodule of the tested voltage source converter valve, continuously boosting the voltage to the rated voltage of the tested voltage source converter valve if the number of abnormal modules in the submodule of the converter valve is determined not to exceed a preset redundancy value, and testing the energy-taking power supply starting voltage of the submodule according to the detected energy-taking power supply voltage, communication state and capacitance of the submodule of the converter valve in the boosting charging process.
3. The method for testing the converter valve of the flexible direct-current transmission voltage source according to claim 1, wherein after the capacitor of the converter valve of the voltage source to be tested is charged to a rated voltage, the step of performing a withstand voltage test on the converter valve of the voltage source to be tested comprises the following steps:
after the capacitor of the tested voltage source converter valve is charged to a rated voltage, after the energy-taking power supply voltage, the communication state and the capacitor voltage-sharing of the voltage source converter valve submodule are determined to be normal, and when the number of the bypass submodules of the voltage source converter valve is less than the preset redundant number, the voltage at two ends of the tested voltage source converter valve, the valve section, the valve tower or the valve hall bridge arm is controlled to rise to the rated voltage, the preset time length is kept, and the voltage withstand test of the converter valve is completed within the preset time length.
4. The method for testing the converter valve of the flexible direct-current transmission voltage source according to claim 1, wherein after the withstand voltage test is completed, the converter valve of the voltage source to be tested is unlocked, and the step of performing the electrical performance test on the converter valve of the voltage source to be tested comprises the following steps:
and controlling the isolating switch to disconnect or close the external test direct-current power supply, unlocking the converter valve of the voltage source to be tested to perform passive unlocking, and performing electrical performance test detection on the converter valve of the voltage source to be tested according to the output waveform of the converter valve of the voltage source to be tested.
5. The method for testing converter valves of a flexible direct current transmission voltage source according to claim 1, wherein the passively unlocking the converter valves of the voltage source to be tested comprises:
according to a preset fixed modulation ratio, passively unlocking a converter valve of a voltage source to be measured in preset different time lengths;
or, according to a preset fixed time length, carrying out passive unlocking on the converter valve of the voltage source to be tested according to preset different modulation ratios.
6. The method for testing the converter valve of the flexible direct-current transmission voltage source according to claim 1, wherein after the withstand voltage test is completed, the converter valve of the voltage source to be tested is unlocked, and the step of performing the electrical performance test on the converter valve of the voltage source to be tested comprises the following steps:
and carrying out active unlocking on the converter valve of the voltage source to be tested, and carrying out electrical performance test detection on the converter valve of the voltage source to be tested according to the output waveform of the converter valve of the voltage source to be tested.
7. The method for testing the converter valve of the flexible direct current transmission voltage source according to claim 1, wherein the actively unlocking the converter valve of the voltage source to be tested comprises the following steps:
according to a preset fixed modulation ratio, carrying out active unlocking on the converter valve of the voltage source to be measured in preset different time lengths;
or, according to a preset fixed time length, carrying out active unlocking on the converter valve of the voltage source to be detected by preset different modulation ratios.
8. The method for testing a converter valve of a flexible direct current transmission voltage source according to claim 1, wherein the method further comprises:
the voltage source converter valve is charged from uncontrolled charging to active charging, the number of each bridge arm submodule is adjusted according to a preset converter valve control adjustment strategy, and an overcurrent protection fixed value of an external direct current power supply is adjusted.
9. A flexible dc transmission voltage source converter valve test power supply unit, characterized in that said power supply unit is adapted to output dc power to provide external test dc power according to any of claims 1-8; the test power supply comprises: the system comprises an incoming line switch protection circuit, a voltage regulating device and a step-up transformer;
one end of the incoming line switch protection circuit is connected to one end of the voltage regulating device, the other end of the incoming line switch protection circuit is connected with an external alternating current power supply, and the incoming line switch protection circuit realizes connection and disconnection of an external alternating current source and the voltage regulating device;
the other end of the voltage regulating device is connected to the primary side of the boosting transformer and is used for regulating the voltage of an external alternating current power supply connected through the incoming line switch protection circuit;
the first end of the secondary side of the boosting transformer is grounded, and the second end of the secondary side of the boosting transformer is used for outputting a direct-current power supply required by the charging and unlocking test.
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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN115047333A (en) * 2022-08-11 2022-09-13 国网经济技术研究院有限公司 Passive unlocking test method and system for offshore platform converter valve wharf
WO2023151607A1 (en) * 2022-02-11 2023-08-17 华北电力科学研究院有限责任公司 Flexible direct current power transmission voltage source converter valve test method and power supply device
CN116990623A (en) * 2023-09-26 2023-11-03 国网江苏省电力有限公司电力科学研究院 Modularized converter valve testing device and testing method

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN117155105A (en) * 2023-11-01 2023-12-01 国网浙江省电力有限公司电力科学研究院 Method and system for controlling starting of direct-current transformer of full direct-current system

Citations (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102323815A (en) * 2011-06-16 2012-01-18 中国电力科学研究院 Method for testing modularized multi-level flexible direct-current transmission valve base control equipment
CN103033701A (en) * 2012-11-30 2013-04-10 许继集团有限公司 Flexible direct current transmission converter valve steady-state high-power running testing device and testing method
CN104269996A (en) * 2014-09-05 2015-01-07 中国西电电气股份有限公司 Auxiliary energy-taking device and method for extra-high voltage converter valve running test
EP2983280A1 (en) * 2014-08-07 2016-02-10 ABB Technology AG Power conversion device
CN105787224A (en) * 2016-05-06 2016-07-20 国网福建省电力有限公司 Non-circulation current simulation model for modularized multi-level current converter and modeling method of non-circulation current simulation model
CN106291295A (en) * 2015-05-29 2017-01-04 中电普瑞科技有限公司 Pipe testing circuit and method between a kind of chain type STATCOM change of current end of the chain
CN109921454A (en) * 2019-04-17 2019-06-21 国家电网有限公司 Flexible direct current system starting method and device based on modular multilevel converter
CN109946600A (en) * 2019-04-03 2019-06-28 国网冀北电力有限公司电力科学研究院 Detect the device and control method of converter valve submodule internal electric performance
CN110596580A (en) * 2019-09-05 2019-12-20 许继集团有限公司 Flexible-straight converter valve overvoltage bypass test method and device
CN111537842A (en) * 2020-04-03 2020-08-14 南京南瑞继保电气有限公司 Testing system and testing method for flexible direct current transmission converter station
CN112269152A (en) * 2020-10-29 2021-01-26 华北电力科学研究院有限责任公司 Transformer and converter valve charging test circuit and method
CN113655324A (en) * 2021-09-03 2021-11-16 广东电网有限责任公司广州供电局 Converter valve operation test topology platform

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102354203B (en) * 2011-06-24 2014-02-12 中国电力科学研究院 Combined test method of dynamic simulation device and engineering control system
CN103809114B (en) * 2014-01-21 2017-01-04 清华大学 The power of a kind of modularization multi-level converter converter valve liquidates assay device
CN109239589B (en) * 2018-07-06 2021-05-18 国网浙江省电力有限公司电力科学研究院 On-site switching-on and switching-off consistency test method for high-voltage hybrid direct-current circuit breaker engineering
CN109980673B (en) * 2019-04-03 2022-07-22 南京南瑞继保电气有限公司 Method for putting modular multilevel converter into operation in live mode and control system
CN114167278B (en) * 2022-02-11 2022-05-17 华北电力科学研究院有限责任公司 Flexible direct-current transmission voltage source converter valve test method and power supply device

Patent Citations (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102323815A (en) * 2011-06-16 2012-01-18 中国电力科学研究院 Method for testing modularized multi-level flexible direct-current transmission valve base control equipment
CN103033701A (en) * 2012-11-30 2013-04-10 许继集团有限公司 Flexible direct current transmission converter valve steady-state high-power running testing device and testing method
EP2983280A1 (en) * 2014-08-07 2016-02-10 ABB Technology AG Power conversion device
CN104269996A (en) * 2014-09-05 2015-01-07 中国西电电气股份有限公司 Auxiliary energy-taking device and method for extra-high voltage converter valve running test
CN106291295A (en) * 2015-05-29 2017-01-04 中电普瑞科技有限公司 Pipe testing circuit and method between a kind of chain type STATCOM change of current end of the chain
CN105787224A (en) * 2016-05-06 2016-07-20 国网福建省电力有限公司 Non-circulation current simulation model for modularized multi-level current converter and modeling method of non-circulation current simulation model
CN109946600A (en) * 2019-04-03 2019-06-28 国网冀北电力有限公司电力科学研究院 Detect the device and control method of converter valve submodule internal electric performance
CN109921454A (en) * 2019-04-17 2019-06-21 国家电网有限公司 Flexible direct current system starting method and device based on modular multilevel converter
CN110596580A (en) * 2019-09-05 2019-12-20 许继集团有限公司 Flexible-straight converter valve overvoltage bypass test method and device
CN111537842A (en) * 2020-04-03 2020-08-14 南京南瑞继保电气有限公司 Testing system and testing method for flexible direct current transmission converter station
CN112269152A (en) * 2020-10-29 2021-01-26 华北电力科学研究院有限责任公司 Transformer and converter valve charging test circuit and method
CN113655324A (en) * 2021-09-03 2021-11-16 广东电网有限责任公司广州供电局 Converter valve operation test topology platform

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2023151607A1 (en) * 2022-02-11 2023-08-17 华北电力科学研究院有限责任公司 Flexible direct current power transmission voltage source converter valve test method and power supply device
CN115047333A (en) * 2022-08-11 2022-09-13 国网经济技术研究院有限公司 Passive unlocking test method and system for offshore platform converter valve wharf
CN116990623A (en) * 2023-09-26 2023-11-03 国网江苏省电力有限公司电力科学研究院 Modularized converter valve testing device and testing method
CN116990623B (en) * 2023-09-26 2023-12-12 国网江苏省电力有限公司电力科学研究院 Modularized converter valve testing device and testing method

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