A low-voltage pressurization test device for controllable phase-commutated converters

Abstract

This invention discloses a low-voltage pressurization test device for controllable commutation converters, comprising: a power supply, a voltage regulator, a test transformer, a converter transformer, a converter valve group, a load resistor, a voltage measuring device, and a current measuring device. The device applies an adjustable test voltage to the low-end converter transformer side, causing the valve side of the controllable commutation converter to output the required test voltage and current. This invention provides technical support for test equipment preparation, short-circuiting of components within the converter valve, and setting of operational sequences, filling a technical gap in low-voltage pressurization test schemes for controllable commutation converter valves.

Description

Technical Field

[0001] This invention relates to power technology, and in particular to a low-voltage pressurization test device for a controllable commutation converter. Background Technology

[0002] The low-voltage pressurization test of the converter transformer is conducted after the completion of the converter transformer body test, the converter valve body and valve control system joint commissioning test, the converter station control and protection device test, and the pole control and valve control joint commissioning test. The purpose of this test is to check the correctness of the primary wiring of the converter transformer, the correctness of the converter valve trigger synchronization voltage and trigger control voltage, the correctness of the primary voltage phase sequence, and the correctness of the valve group triggering sequence. A low-voltage pressurization test of the converter transformer with valve groups must be performed before the converter valves undergo high-voltage charging.

[0003] Existing national standards or reference materials regarding low-voltage pressurization tests for converters are simplistic and only apply to traditional UHV converters. For controllable commutation converters, a new type of topology converter, there is no mature testing device in the current technology. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention discloses a low-voltage pressurization test device for controllable commutation converters, characterized by comprising:

[0005] power supply,

[0006] Voltage regulator,

[0007] Test transformer,

[0008] Converter transformer,

[0009] Converter valve assembly,

[0010] Load resistance,

[0011] Voltage measuring device, and,

[0012] Current measuring device

[0013] in,

[0014] The device is used to apply an adjustable test voltage to the low-end converter grid side so that the valve side of the controllable phase-commutation converter outputs the required test voltage and current.

[0015] Preferably, in the low-voltage pressurization test device for a controllable commutation converter, wherein,

[0016] The power supply is AC power.

[0017] Preferably, in the low-voltage pressurization test device for a controllable commutation converter, wherein,

[0018] The load resistor is a DC resistor, and its resistance value is determined through simulation.

[0019] Preferably, in the low-voltage pressurization test device for a controllable commutation converter, wherein,

[0020] The technical parameters of the voltage regulator and the test transformer were determined through simulation.

[0021] Preferably, in the low-voltage pressurization test device for a controllable commutation converter, wherein,

[0022] The simulation was performed using transient simulation software.

[0023] Preferably, in the low-voltage pressurization test device for a controllable commutation converter, wherein,

[0024] During the low-pressure pressurization test, retain 1 to 2 thyristor stages and short-circuit the rest.

[0025] Therefore, this invention provides a low-pressure pressurization test solution for controllable commutation converter valves capable of withstanding commutation failure. This solution outlines the equipment requirements, overall wiring configuration, test sequence, and simulation iterative calculation method. Based on the simulation iterative calculation, the number of power electronic components, voltage regulator, and test transformer capacity can be ultimately determined. Furthermore, this invention provides technical support for test equipment preparation, short-circuiting of components within the converter valve, and setting of operational sequence values, filling a technical gap in low-pressure pressurization test solutions for controllable commutation converter valves. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the structure of one arm of a controllable commutated converter (CLCC) in one embodiment of the present invention;

[0027] Figure 2 This is a schematic diagram of the structure of a low-voltage pressurization test device for a controllable commutation converter in one embodiment of the present invention;

[0028] Figure 3 This is a schematic diagram of the process of determining DC resistance, voltage regulator, test transformer, etc. through simulation in one embodiment of the present invention;

[0029] Figure 4 This is a schematic diagram of the control timing of a low-pressure pressurization test device for a controllable commutator operating in the LCC mode of the controllable commutator valve, according to one embodiment of the present invention.

[0030] Figure 5 This is a schematic diagram of the control timing of a low-pressure pressurization test device for a controllable commutator operating in the CLCC mode of the controllable commutator valve, according to one embodiment of the present invention.

[0031] The attached figures are labeled as follows:

[0032] U: Test voltage,

[0033] V11: Main thyristor valve in the main branch circuit.

[0034] V12: The main IGBT valve in the main branch circuit.

[0035] V13: Auxiliary IGBT valve in the auxiliary branch.

[0036] V14: Auxiliary thyristor valve in the auxiliary branch.

[0037] R d DC resistance

[0038] I d Direct current,

[0039] U d DC voltage. Detailed Implementation

[0040] To enable those skilled in the art to understand the technical solutions disclosed in this invention, the technical solutions of various embodiments will be described below in conjunction with the embodiments and related drawings. The described embodiments are some, but not all, of the embodiments of this invention. The terms "first," "second," etc., used in this invention are used to distinguish different objects, not to describe a specific order. Furthermore, "comprising" and "having," and any variations thereof, are intended to be comprehensive and non-exclusive inclusion. For example, a process, method, system, product, or device that includes a series of steps or units is not limited to the steps or units listed, but may optionally include steps or units not listed, or may optionally include other steps or units inherent to these processes, methods, systems, products, or devices.

[0041] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of the invention. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a mutually exclusive, independent, or alternative embodiment. Those skilled in the art will understand that the embodiments described herein can be combined with other embodiments.

[0042] See Figure 1 In this invention, the controllable commutator (CLCC) is a current source type converter valve with controllable turn-off capability. Each bridge arm is equivalent to a converter valve group. Each bridge arm includes a main branch and an auxiliary branch connected in parallel. The main branch is composed of a main thyristor valve V11 and a main IGBT valve V12 connected in series, and the auxiliary branch is composed of an auxiliary IGBT valve V13 and an auxiliary thyristor valve V14 connected in series.

[0043] It should be noted that, among them, Figure 1 In this system, the main valve of the main IGBT valve is V12, and the main IGBT valve V12 also includes a V12P valve as a sub-valve of V12.

[0044] See Figure 2 This invention discloses a low-voltage pressurization test device for a controllable commutation converter, comprising:

[0045] AC power supply

[0046] Voltage regulator,

[0047] Test transformer,

[0048] Converter transformer,

[0049] Converter valve assembly,

[0050] Load resistance,

[0051] Voltage measuring device, and,

[0052] Current measuring device

[0053] in,

[0054] The device is used to apply an adjustable test voltage to the low-end converter transformer side, so that the valve side output of the controllable phase-commutated converter reaches the required test voltage and current.

[0055] Combination Figure 2 An AC power supply is connected to a voltage regulator. Through the action of a synchronization voltage, the voltage regulator can adjust the voltage between the AC power supply and the voltage regulator. The voltage regulator is further connected to a converter transformer via a test transformer. The converter transformer connects all the converter valve groups of the controllable commutation converter. Each converter valve group includes a bridge arm, which includes a main branch and an auxiliary branch connected in parallel. The main branch consists of a main thyristor valve V11 and a main IGBT valve V12 connected in series, and the auxiliary branch consists of an auxiliary IGBT valve V13 and an auxiliary thyristor valve V14 connected in series.

[0056] For example, such as Figure 2 As shown from left to right:

[0057] The three-phase lines on one side of the converter transformer are respectively connected to the first end of the first to third converter valve groups in the first group of converter valve groups, and the second end of the first to third converter valve groups is connected to the "+" terminal.

[0058] The three-phase lines on one side of the converter transformer are also respectively connected to the second ends of the fourth to sixth converter valve groups in the second group of converter valve groups. The first ends of the fourth to sixth converter valve groups are connected to the second ends of the seventh to ninth converter valve groups in the third group of converter valve groups. The second ends of the seventh to ninth converter valve groups are connected to each other.

[0059] The three-phase lines on the other side of the converter transformer are respectively connected to the first end of the seventh to ninth converter valve groups in the third group of converter valve groups, and the second end of the tenth to twelfth converter valve groups in the fourth group of converter valve groups. The first ends of the tenth to twelfth converter valve groups are all connected to the "-" end.

[0060] A resistor is connected between the "+" terminal and the "-" terminal, and the resistor serves as a load resistor.

[0061] It should be noted that,

[0062] Due to the presence of the controllable commutator, the current flowing between the "+" and "-" terminals is a direct current I. d Therefore, the resistor is denoted as DC resistance R. d The voltage across its terminals is denoted as DC voltage U. d ;

[0063] When wiring the device, according to the component retention principle (see below), the retainable devices of each sub-valve of the controllable commutation converter are determined, and other thyristors or IGBTs are short-circuited (i.e., short-connected) with temporary shorting wires to temporarily connect and form the device. Figure 2 The 12-pulse rectifier wiring shown converts the DC side positive and negative voltages, i.e., the DC voltage U. d Lead it out, and then connect the corresponding DC resistor R on the DC side. d .

[0064] The principle for retaining parts is:

[0065] When conducting low-voltage pressurization tests on a controllable commutator converter, retain one or two thyristor stages (short-circuit the remaining stages) and operate it in rectification mode. It should be noted that the test voltage applied to the grid side of the converter transformer must meet the following conditions: the test voltage must be significantly lower than the actual operating voltage of the project, and it must ensure that all bridge arms of the controllable commutator are conducting normally and that the circuit operating current is normal.

[0066] For example, in a controllable commutated converter, the operating voltage requirements of each power electronic device are assumed to be the voltage U of a single-stage thyristor. THY Single-stage IGBT voltage U IGBT :

[0067] U THY_min ≤U THY ≤U THY_max ,

[0068] U IGBT_min ≤U IGBT ≤U IGBT_max ,

[0069] Thyristors and IGBTs must operate at voltages higher than the lower limit of their operating voltage to function properly; otherwise, they will fail to conduct or experience a power extraction failure. They must also operate at voltages lower than the upper limit of their operating voltage to meet the device's withstand voltage requirements.

[0070] To ensure that the thyristors and IGBTs meet the requirements for normal operation, it is necessary to determine the number of test stages for the power electronic devices through simulation iterations, setting the maximum number of each device to no more than n (n is set to 3). The choice of n to 3 is primarily based on the perspective of RC electrical design. It is known that thyristors and IGBTs generally divide voltage according to their respective RC parameters. The different functions of the main and auxiliary branches lead to differences in the selection of RC parameters. Furthermore, the different RC design principles of thyristors and IGBTs result in differences in their respective RC parameters, ultimately affecting the different voltage division between the thyristors and IGBTs in the main and auxiliary branches during low-voltage pressurization tests.

[0071] For example, this invention determines that the upper limit n of the number of power electronic device stages is 3, and the number of thyristor device stages protected by one engineering saturated reactor is not less than 3. Therefore, it is determined that one saturated reactor is retained in each of the main and auxiliary branches during the low-voltage pressurization test. During the low-voltage pressurization test, the operating voltage of each sub-valve (e.g., the sub-valves of V11, V12, V13, and V14) is much lower than the actual operating voltage and much lower than the operating voltage of the surge arrester. Therefore, the surge arrester is retained unchanged and has no impact on the low-voltage pressurization test.

[0072] Furthermore, the DC current I is clarified. d Value range:

[0073] 2A≤I d ≤4A,

[0074] It should be noted that when I d If the voltage is too low, the intermittent protection function of the converter valve may be triggered, causing the test converter to malfunction. Considering both safety and economy, the test voltage should be as low as possible, and the required power supply capacity as low as possible, while ensuring the normal operation of all test thyristors and IGBTs. Therefore, I is set... d The value should not exceed 4A and should not be less than 2A. Based on the final range of DC current Id, the DC resistance R can be further adjusted. d Select or adjust accordingly.

[0075] Furthermore, during the simulation iteration, the initial value of all device stages is set to 1, and the device stages are shown in the table below.

[0076] Table 1. Components retained in the test converter valve

[0077]

[0078] During the low-voltage pressurization test, the firing angle α ranges from [30°, 90°]. When the firing angle is 0°≤α≤90°, the larger the firing angle, the larger the DC side voltage, which is more beneficial for the device's energy extraction, but also places higher demands on the device's withstand voltage. Therefore, simulation calculations are performed on the low-voltage pressurization operation under two extreme conditions: firing angle α=30° and α=90°. The simulation iteration method is described in [link to simulation]. Figure 3 , Figure 3 This is a schematic diagram illustrating the process of determining DC resistance, voltage regulator, test transformer, etc., through simulation according to the present invention. The simulation iteration method is implemented entirely in transient simulation software and includes the following steps:

[0079] A low-voltage pressurization test circuit model of the device was built in transient simulation software;

[0080] Adjust and input the key component parameters for each bridge arm, including, for example: V11 sub-valve stage 1 thyristor, V12 sub-valve stage 1 IGBT, V12 sub-valve stage 1 diode, V12 sub-valve stage 1 bypass thyristor, V13 sub-valve stage 1 IGBT, and V14 sub-valve stage 1 thyristor.

[0081] Adjust the test voltage U;

[0082] Adjust and input other component parameters, for example, including: V11 sub-valve a1 level thyristor, V12 sub-valve b1 level IGBT, V12 sub-valve b2 level diode, V12 sub-valve b3 level bypass thyristor, V13 sub-valve c level IGBT, and V14 sub-valve d1 level thyristor.

[0083] To determine whether a single-stage power electronic device meets the withstand voltage and power extraction requirements, for example, after adjusting and inputting other component parameters as described above, the following parameters are further calculated using transient simulation software to determine whether the single-stage power electronic device meets the withstand voltage and power extraction requirements: Voltage U of the V11 sub-valve a1-stage thyristor. V11THY The voltage U of the bypass thyristor of the V12 sub-valve b3 stage V12THY The voltage U of the V14 sub-valve d1 stage thyristor V14THY The voltage U of the V12 sub-valve b1 stage IGBT V12IGBT The voltage U of the V13 sub-valve c-class IGBT V13IGBT The voltage U of the diode at stage b2 of sub-valve V12 V12DIO ;

[0084] If it is determined that the requirements are not met, return to the steps above for adjusting the test voltage U until it is determined that the requirements are met.

[0085] Adjust the DC resistor value R d ;

[0086] Determine whether the DC current flowing through the DC resistor satisfies the requirement Id∈[2,4], i.e., the DC current I mentioned above. d The range of values ​​is: 2A≤I d ≤4A;

[0087] If the DC current does not meet the requirements, return to the above steps to adjust the DC resistance value R. d The steps are repeated until the requirement is met;

[0088] Determine the capacity of the voltage regulator and test transformer; it should be noted that the capacity of the voltage regulator and test transformer is determined using transient simulation software, and whether such voltage regulators and test transformers actually exist in reality needs further evaluation.

[0089] Determine whether a voltage regulator or test transformer that meets the requirements actually exists;

[0090] If it is determined that there is no voltage regulator or test transformer that meets the requirements, then return to the above-mentioned adjustment of the DC resistance value R. d The steps are followed until it is determined that a voltage regulator and test transformer that meet the requirements actually exist;

[0091] It is understandable that the above simulation iteration method can ultimately obtain the parameters of a single-stage power electronic device that meets the withstand voltage and energy extraction requirements, a DC resistor that meets the DC current requirements, and a voltage regulator and test transformer that meet the requirements.

[0092] Therefore, as can be seen from the preceding text, this invention determines the number of stages for each power electronic device based on the simulation iteration results under two firing angles, and obtains the relevant technical parameter requirements for the DC resistance Rd, voltage regulator, and test transformer.

[0093] See further Figure 4 and Figure 5 In another embodiment,

[0094] For the device disclosed in this invention, when the device is running, the controllable commutator can operate in LCC mode or CLCC mode. That is, to carry out the low-pressure pressurization test, two operating modes need to be performed respectively. When the controllable commutator is running in CLCC mode, the forced commutation operating sequence is adopted.

[0095] Controllable commutator valve LCC mode control timing as follows Figure 4 As shown. The switching on and off of each branch of a single converter valve group is based on the CP signal issued by the pole controller. For ease of understanding, for a single converter valve group, bridge arm 1 is the bridge arm containing V11 and V12, bridge arm 3 is the bridge arm containing V13 and V14, and the switching sequence of each branch is as follows:

[0096] (1) Tcp1 At any given moment, after the valve controller receives the bridge arm 1 trigger command (CP1 signal) sent by the polar controller, it simultaneously triggers the conduction of valves V11 and V12P.

[0097] (2) Approximately 6.67 ms (120°) after the CP signal is issued T cp3 At that moment, the valve control receives the trigger signal CP3 from bridge arm 3, and bridge arm 1 begins to commutate to bridge arm 3.

[0098] Controllable commutator valve CLCC mode control timing as follows Figure 5 As shown. The switching on and off of each branch of a single converter valve group is based on the CP signal issued by the pole controller. For ease of understanding, for a single converter valve group, bridge arm 1 is the bridge arm containing V11 and V12, bridge arm 3 is the bridge arm containing V13 and V14, and the switching sequence of each branch is as follows:

[0099] (1) T cp1 At any given moment, after the valve controller receives the bridge arm 1 trigger command (CP1 signal) sent by the polar controller, it simultaneously triggers the conduction of valves V11, V12, and V13;

[0100] (2) Approximately 6.67 ms (120°) after the CP signal is issued T cp3 At that moment, the valve control receives the trigger signal CP3 from bridge arm 3, and bridge arm 1 begins to commutate to bridge arm 3;

[0101] (3) T cp3 At that moment, V12 is off, V14 is on, and V14 conducts within the specified interval. T con14 ;

[0102] (4) T off13 At time t, V13 is turned off, with a delay of ΔT relative to the time V12 is turned off.

[0103] Those skilled in the art should also understand that the embodiments described in the specification are all preferred embodiments, and the actions, modules, and units involved are not necessarily essential to the present invention.

[0104] In the above embodiments, the descriptions of each embodiment have different focuses. For parts not described in detail in a certain embodiment, please refer to the relevant descriptions in other embodiments.

[0105] In the several embodiments provided by this invention, it should be understood that the disclosed methods can be implemented as corresponding functional units, processors, or even systems, wherein the various parts of the system can be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs. Furthermore, each functional unit can be integrated into one processing unit, or each unit can exist independently, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit. If the integrated unit is implemented as a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this invention, in essence, or the part that contributes to the prior art, or all or part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which can be a smartphone, personal digital assistant, wearable device, laptop, or tablet) to execute all or part of the steps of the methods described in the various embodiments of this invention. The aforementioned storage media include: USB flash drives, read-only memory (ROM), random access memory (RAM), portable hard drives, magnetic disks, optical disks, and other media that can store program code.

[0106] The above-described embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A low-voltage pressurization test device for a controllable commutated converter, characterized in that, include: power supply, Voltage regulator, Test transformer, Converter transformer, Converter valve assembly, Load resistance, Voltage measuring device, and, Current measuring device in, The power supply is AC power; The load resistor is a DC resistor, and its resistance value is determined through simulation. An AC power supply is connected to a voltage regulator; the voltage regulator is further connected to a converter transformer via a test transformer, and the converter transformer is connected to all the converter valve groups of the controllable phase-commutating converter. The converter transformer connects all the converter valve groups of the controllable commutation converter. Each converter valve group includes a bridge arm, which includes a main branch and an auxiliary branch connected in parallel. The main branch is composed of a main thyristor valve V11 and a main IGBT valve V12 connected in series, and the auxiliary branch is composed of an auxiliary IGBT valve V13 and an auxiliary thyristor valve V14 connected in series. All converter valve assemblies include the first through fourth groups of converter valve assemblies, among which... The first group of converter valve groups includes the first to third converter valve groups; the second group of converter valve groups includes the fourth to sixth converter valve groups; the third group of converter valve groups includes the seventh to ninth converter valve groups; and the fourth group of converter valve groups includes the tenth to twelfth converter valve groups. One end of the first to third converter valve groups is connected to the "+" terminal, and the other end of the first to third converter valve groups is connected to one end of the fourth to sixth converter valve groups respectively. The other ends of the fourth to sixth converter valve groups are connected together, and one end of the seventh to ninth converter valve groups is connected together. Furthermore, the other ends of the fourth to sixth converter valve groups after being connected together are connected to one end of the seventh to ninth converter valve groups after being connected together. The other ends of the seventh to ninth converter valve groups are respectively connected to one end of the tenth to twelfth converter valve groups, and the other ends of the tenth to twelfth converter valve groups are all connected to the "-" end; A DC resistor is connected between the "+" terminal and the "-" terminal; The low-voltage pressurization test device is used to apply an adjustable test voltage to the low-end converter transformer side so that the valve side of the controllable phase-commutation converter outputs the required test voltage and current. A low-pressure pressurization test circuit model of the low-pressure pressurization test device was constructed in transient simulation software; Adjust the adjustable test voltage U; Adjust and input other component parameters, including: V11 sub-valve a1 level thyristor, V12 sub-valve b1 level IGBT, V12 sub-valve b2 level diode, V12 sub-valve b3 level bypass thyristor, V13 sub-valve c level IGBT, and V14 sub-valve d1 level thyristor. To determine whether a single-stage power electronic device meets the withstand voltage and power extraction requirements, after adjusting and inputting other component parameters as described above, transient simulation software is used to further calculate whether the following parameters meet the requirements: Voltage U of the V11 sub-valve a1-stage thyristor. V11THY The voltage U of the bypass thyristor of the V12 sub-valve b3 stage V12THY The voltage U of the V14 sub-valve d1 stage thyristor V14THY The voltage U of the V12 sub-valve b1 stage IGBT V12IGBT The voltage U of the V13 sub-valve c-class IGBT V13IGBT The voltage U of the diode at stage b2 of sub-valve V12 V12DIO ; If it is determined that the requirements are not met, return to the steps described above for adjusting the adjustable test voltage U until the requirements are met. Adjust the resistance value R of the DC resistor d ; Determine whether the DC current flowing through the DC resistor satisfies I. d The requirement ∈[2,4], i.e., DC current I d The range of values ​​is: 2A≤I d ≤4A; If the DC current does not meet the requirements, return to the above-mentioned adjustment of the DC resistor value R. d The steps are repeated until the requirement is met; Determine the capacity of the voltage regulator and test transformer; this is the capacity of the voltage regulator and test transformer determined using transient simulation software. Whether such voltage regulators and test transformers actually exist in reality needs further evaluation. Determine whether a voltage regulator or test transformer that meets the requirements actually exists; If it is determined that there is no voltage regulator or test transformer that meets the requirements, then return to the above-mentioned adjustment of the DC resistance value R. d The process continues until it is determined that a voltage regulator and test transformer that meet the requirements actually exist.

2. The low-voltage pressurization test device for a controllable commutated converter according to claim 1, characterized in that, The technical parameters of the voltage regulator and the test transformer were determined through simulation.

3. A low-voltage pressurization test device for a controllable commutated converter according to claim 1 or 2, characterized in that, The simulation was performed using transient simulation software.

4. The low-voltage pressurization test device for a controllable commutated converter according to claim 1, characterized in that, During the low-pressure pressurization test, retain 1 to 2 thyristor stages and short-circuit the rest.

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