A phase sequence adaptive grid-connected control method and system of a chain SVG device

Abstract

The application discloses a phase sequence adaptive grid-connection control method and system of a chain SVG device, and the method comprises the following steps: 1) obtaining three-phase line voltage input by the SVG to obtain three-phase voltage synchronization signals; 2) taking the three-phase voltage as the input of a software phase-locked loop, and using the d and q axis components of the output voltage to judge the voltage phase sequence; if the voltage phase sequence is a negative sequence, then adjusting the voltage of any two phases to adjust the three-phase voltage to a positive sequence; 3) obtaining the data of the SVG three-phase current and the three-phase synchronization voltage when the SVG high-voltage switch is closed; 4) obtaining the corresponding line sequence relationship between the three-phase synchronization voltage and the three-phase input voltage according to the data of the SVG three-phase current and the three-phase synchronization voltage when the high-voltage switch is charged; and 5) adjusting the line sequence of the three-phase current collection signals output by the SVG, calculating three-phase modulation waves, and distributing the three-phase modulation waves to the three-phase converter chains. The application has the advantages of automatically correcting the phase sequence of the synchronization voltage, improving the debugging efficiency and the like.

Description

Technical Field

[0001] This invention mainly relates to the field of power management technology, specifically to a phase sequence adaptive grid-connected control method and system for a chain-type SVG device. Background Technology

[0002] In recent years, three-phase chained SVG (Static Var Compensator) has been increasingly widely used in power grids as a high-voltage dynamic reactive power compensation device. A three-phase chained SVG is a grid-connected device, and to achieve its control, it needs to acquire real-time input voltage information. In engineering, chained SVG devices often collect voltage transformer signals from the high-voltage bus as their own voltage synchronization signals, rather than directly detecting the input voltage at the device's incoming line. As a grid-connected device, the normal operation of a chained SVG depends on the correct correspondence between the three-phase input voltage and the three-phase synchronization voltage, requiring a positive voltage phase sequence. Objectively, this necessitates that on-site construction personnel strictly adhere to the ABC three-phase wiring sequence for primary and secondary connections. However, at SVG installation sites, due to various reasons such as missing or incorrect cable phase sequence markings, incorrect wiring by construction personnel, and reversed secondary cables on the busbar PT (Position Transformer), abnormal connections of primary and secondary cables are unavoidable. This results in the input voltage and synchronization voltage not correctly corresponding in three phases, leading to overcurrent during SVG startup, affecting equipment commissioning and safety. Therefore, before SVG is put into operation, the manufacturer's commissioning personnel need to carefully check the primary and secondary wiring of the device on-site and use specialized instruments and equipment to check the relevant voltage and current waveforms for phase matching. If an incorrect phase sequence is found, manual adjustment of the cable wiring is required, which is time-consuming and tedious, and also places higher demands on the skills of the commissioning personnel. Therefore, developing a grid-connected control method for chain-type SVG that can automatically adapt to abnormal phase sequence of grid voltage has great application value.

[0003] To enable grid-connected devices such as SVG to identify and correct abnormal phase sequences in the power grid voltage, and thus adapt to grid-connected operation, many beneficial explorations have been conducted in the industry. A search revealed the following patents and documents strongly related to this invention:

[0004] The invention patent application (application number CN201410280773.X) discloses a line sequence active detection and adaptive system and its implementation method. The method first obtains the synchronous voltage phase information through voltage zero-crossing phase-locked loop and uses rotating coordinate transformation to obtain the d-axis and q-axis components of the voltage to determine the voltage phase sequence. Then, based on the phase sequence relationship, it controls the three-phase controlled bridge to output a short-circuit pulse to short-circuit the power grid at the positive zero-crossing point of the voltage to obtain the short-circuit current. Based on the response of the short-circuit current, it determines the line sequence relationship between the synchronization signal and the main circuit cables. Finally, it automatically adjusts the phase of the synchronous voltage according to the phase sequence and line sequence relationship to control the normal grid-connected operation of the device. This invention method is only applicable to three-phase bridge circuits and not to chain-type SVG. Moreover, it requires short-circuiting the power grid for a short time through internal power transistors, which poses certain risks when applied to high-voltage fields.

[0005] The above analysis shows that the current technical solutions for achieving phase sequence adaptive grid-connected operation of devices such as SVG still have certain limitations, mainly reflected in the following aspects:

[0006] (1) Limited scope of application, such as only applicable to low-voltage SVG devices using a three-phase bridge topology or only applicable to SVG devices equipped with their own input voltage detection equipment, etc.

[0007] (2) Limited functionality, such as only being used to detect whether the phase sequence is abnormal. When the phase sequence is abnormal, it cannot realize the mis-sequence correction of the grid-connected control strategy of the device. Summary of the Invention

[0008] The technical problem to be solved by this invention is: in view of the problems existing in the prior art, this invention provides a phase sequence adaptive grid-connected control method and system for a chain-type SVG device that automatically corrects the phase sequence of synchronous voltage and the correspondence between primary and secondary cables, thereby improving the debugging efficiency.

[0009] To solve the above-mentioned technical problems, the technical solution proposed by this invention is as follows:

[0010] A phase sequence adaptive grid-connected control method for a chain-type SVG device includes the following steps:

[0011] 1) Obtain the three-phase line voltage input from the chain-type SVG device and calculate the three-phase phase voltage synchronization signal;

[0012] 2) Use the three-phase voltage as the input of the software phase-locked loop, and use the d-axis and q-axis components of the voltage output by the software phase-locked loop to determine the voltage phase sequence; if the voltage phase sequence is negative, swap any two phase voltages to adjust the three-phase voltage to positive sequence.

[0013] 3) Obtain data on the three-phase current and three-phase synchronous voltage of the SVG during high-voltage closing;

[0014] 4) Based on the data of the three-phase current and three-phase synchronous voltage of the SVG during high-voltage closing and charging, the corresponding line sequence relationship between the three-phase synchronous voltage and the three-phase input voltage is obtained;

[0015] 5) Based on the corresponding line sequence relationship between the three-phase synchronous voltage and the three-phase input voltage, the line sequence of the three-phase current acquisition signal output by the chain SVG device is adjusted, the three-phase modulation wave is calculated, and the three-phase modulation wave is correspondingly allocated to the three-phase converter chain.

[0016] As a further improvement to the above technical solution:

[0017] In step 4), the phase synchronization voltage is multiplied by each phase current and summed according to the number of sampling points in one fundamental cycle. If the sum of the product of the phase synchronization voltage and one phase current is positive and greater than a set threshold, it indicates that the phase synchronization voltage is in phase with the phase input voltage.

[0018] The specific process of step 4) is as follows:

[0019] The A-phase synchronization voltage is multiplied by the A, B, and C phase currents output by the chain SVG device, and the sum is calculated based on the number of sampling points in one fundamental cycle. If the sum of the multiplication of the A-phase synchronization voltage and the A-phase current is positive and greater than a set threshold, it indicates that the A-phase synchronization voltage and the A-phase current are in phase, and the A-phase synchronization voltage and the A-phase input voltage correspond correctly. Otherwise, the A-phase synchronization voltage and the A-phase input voltage do not correspond.

[0020] If the phase A synchronization voltage and the phase A input voltage do not correspond correctly, then it is further determined whether the sum of the product of the phase A synchronization voltage and the phase B current is positive and greater than a set threshold. If it is satisfied, it indicates that the phase A synchronization voltage and the phase B input voltage correspond correctly; otherwise, they do not correspond.

[0021] If the phase A synchronization voltage and phase B input voltage do not correspond correctly, then it is further determined whether the sum of the product of phase A synchronization voltage and phase C current is positive and greater than a set threshold. If it is satisfied, it indicates that the phase A synchronization voltage and phase C input voltage correspond correctly.

[0022] If the A-phase synchronization voltage and the C-phase input voltage still do not correspond correctly, reverse the phases of all three-phase synchronization voltages and repeat the above steps.

[0023] The phase B synchronization voltage is multiplied by the three phase B, C, and A currents output by the chain SVG device, and the sum is calculated based on the number of sampling points in one fundamental cycle. If the sum of the multiplication of the phase B synchronization voltage and the phase B current is positive and greater than a set threshold, it indicates that the phase B synchronization voltage and the phase B current are in phase, and the phase B synchronization voltage and the phase B input voltage correspond correctly. Otherwise, the phase B synchronization voltage and the phase B input voltage do not correspond.

[0024] If the phase B synchronization voltage and the phase B input voltage do not correspond correctly, then it is further determined whether the sum of the product of the phase B synchronization voltage and the phase C current is positive and greater than a set threshold. If it is satisfied, it indicates that the phase B synchronization voltage and the phase C input voltage correspond correctly; otherwise, they do not correspond.

[0025] If the phase B synchronization voltage and the phase C input voltage do not correspond correctly, then it is further determined whether the sum of the product of the phase B synchronization voltage and the phase A current is positive and greater than a set threshold. If it is satisfied, it indicates that the phase B synchronization voltage and the phase A input voltage correspond correctly.

[0026] Finally, the correspondence between the C-phase synchronization voltage and the input voltage of each phase was determined, and the corresponding line sequence relationship between the three-phase synchronization voltage and the three-phase input voltage was finally obtained.

[0027] After step 5), step 6) is also included, adjusting the bus current offset angle and correcting the phase difference between the three-phase bus current and the three-phase synchronization signal after phase sequence adjustment.

[0028] The bus current offset angle is 0°, -120°, or +120°.

[0029] In step 5), the specific process of allocating the three-phase modulation waves to the three-phase converter chains is as follows: if the A-phase synchronization voltage corresponds to the A-phase input voltage, then the calculated A-phase modulation wave is allocated to the A-phase converter chain; if the A-phase synchronization voltage corresponds to the B-phase input voltage, then the calculated A-phase modulation wave is allocated to the B-phase converter chain; if the A-phase synchronization voltage corresponds to the C-phase input voltage, then the calculated A-phase modulation wave is allocated to the C-phase converter chain; similarly, the B and C-phase modulation waves can be allocated to the converter chains of the corresponding line sequence.

[0030] In step 5), the modulation signals of each phase commutator chain are superimposed with the modulation wave correction values ​​of each phase to generate the final modulation signal.

[0031] In step 1), determine and set whether the chain-type SVG device is a direct-connected type or a step-down type. Calculate the three-phase phase voltages from the acquired three-phase line voltages. If it is a direct-connected type, the input phase voltage of the chain-type SVG device lags the bus line voltage by 30°, ua=(uab-uca) / 3, ub=(ubc-uab) / 3, uc=(uca-ubc) / 3; if it is a step-down type, the SVG input phase voltage is in phase with the bus line voltage.

[0032] The specific process of step 2) is as follows: After the software phase-locked loop stabilizes and locks in phase, if Ud is greater than the set threshold and Uq is less than the set threshold, the voltage phase sequence can be determined to be positive; otherwise, the voltage phase sequence is negative.

[0033] The present invention also discloses a phase sequence adaptive grid-connected control system for a chain-type SVG device, comprising:

[0034] The line-phase conversion module is used to obtain the three-phase line voltage input from the chain-type SVG device and calculate the three-phase phase voltage.

[0035] The phase sequence detection and adjustment module is used to take the three-phase voltage as the input of the software phase-locked loop and use the d-axis and q-axis components of the voltage output by the software phase-locked loop to determine the voltage phase sequence; if the voltage phase sequence is negative, any two phase voltages are swapped to adjust the three-phase voltage to positive sequence.

[0036] The recording module is used to acquire data on the three-phase current and three-phase synchronous voltage of the SVG during high-voltage closing.

[0037] The line sequence determination module is used to obtain the corresponding line sequence relationship between the three-phase synchronous voltage and the three-phase input voltage based on the data of the SVG three-phase current and three-phase synchronous voltage during high-voltage closing and charging.

[0038] The modulation signal calculation module is used to adjust the line sequence of the three-phase current acquisition signal output by the chain SVG device according to the corresponding line sequence relationship between the three-phase synchronous voltage and the three-phase input voltage, further calculate the three-phase modulation wave, and allocate the three-phase modulation wave to the three-phase converter chain accordingly.

[0039] The present invention further discloses a computer-readable storage medium having a computer program stored thereon, the computer program executing the steps of the phase sequence adaptive grid-connected control method for the chained SVG device as described above when run by a processor.

[0040] The present invention also discloses a computer device, including a memory and a processor, wherein the memory stores a computer program, and the computer program, when run by the processor, executes the steps of the phase sequence adaptive grid-connected control method of the chain SVG device as described above.

[0041] Compared with the prior art, the advantages of the present invention are as follows:

[0042] This invention addresses the problem of manual intervention required when the input voltage or synchronization voltage cable wiring is incorrect in chain-type SVG devices. Through the steps of phase sequence detection, phase sequence adjustment, and wiring sequence correction, it automatically corrects the synchronization voltage phase sequence and the correspondence between primary and secondary cables, realizing automatic error correction of the SVG control algorithm. This allows the device to operate normally in grid connection without the need for manual intervention to solve cable wiring problems, thereby improving the efficiency of on-site equipment commissioning. Attached Figure Description

[0043] Figure 1 This is a flowchart of the method of the present invention in an embodiment.

[0044] Figure 2 This is an example diagram of a specific application of the method of the present invention. Detailed Implementation

[0045] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0046] like Figure 1 As shown, the phase sequence adaptive grid-connected control method for the chain-type SVG device in this embodiment includes the following steps:

[0047] 1) Obtain the three-phase line voltage input from the chain SVG device through the bus voltage transformer, and calculate the three-phase phase voltage synchronization signal;

[0048] 2) Use the three-phase voltage as the input of the software phase-locked loop, and use the d-axis and q-axis components of the voltage output by the software phase-locked loop to determine the voltage phase sequence. If the voltage phase sequence is negative, swap any two phase voltages to adjust the three-phase voltage to positive sequence.

[0049] 3) Obtain data on the three-phase current and three-phase synchronous voltage of the SVG during high-voltage closing;

[0050] 4) Based on the data of the three-phase current and three-phase synchronous voltage of the SVG during high-voltage closing and charging, the corresponding line sequence relationship between the three-phase synchronous voltage and the three-phase input voltage is obtained;

[0051] 5) Based on the corresponding line sequence relationship between the three-phase synchronous voltage and the three-phase input voltage, the line sequence of the three-phase current acquisition signal output by the chain SVG device is adjusted, and the three-phase modulation wave is further calculated. Then, the three-phase modulation wave is allocated to the three-phase converter chain accordingly.

[0052] This invention addresses the problem of manual intervention required when the input voltage or synchronization voltage cable wiring is incorrect in chain-type SVG devices. Through the steps of phase sequence detection, phase sequence adjustment, and wiring sequence correction, it automatically corrects the synchronization voltage phase sequence and the correspondence between primary and secondary cables, realizing automatic error correction of the SVG control algorithm. This allows the device to operate normally in grid connection without the need for manual intervention to solve cable wiring problems, thereby improving the efficiency of on-site equipment commissioning.

[0053] In one specific embodiment, in step 4), the phase synchronization voltage is multiplied by each phase current, and the results are summed according to the number of sampling points in one fundamental cycle. If the sum of the products of the phase synchronization voltage and one of the phase currents is positive and greater than a set threshold, it indicates that the phase synchronization voltage is in phase with the phase input voltage. The specific process is as follows:

[0054] The A-phase synchronization voltage is multiplied by the A, B, and C phase currents of the chain SVG device, and the sum is calculated based on the number of sampling points in one fundamental cycle. If the sum of the multiplication of the A-phase synchronization voltage and the A-phase current is positive and greater than a set threshold, it indicates that the A-phase synchronization voltage and the A-phase current are in phase, and the A-phase synchronization voltage and the A-phase input voltage correspond correctly. Otherwise, the A-phase synchronization voltage and the A-phase input voltage do not correspond.

[0055] If the phase A synchronization voltage and phase A input voltage do not correspond correctly, then it is further determined that the sum of the product of phase A synchronization voltage and phase B current is positive and greater than a set threshold. If this condition is met, it indicates that the phase A synchronization voltage and phase B input voltage correspond correctly; otherwise, they do not correspond.

[0056] If the synchronization voltage of phase A and the input voltage of phase B do not correspond correctly, then it is further determined that the sum of the product of the synchronization voltage of phase A and the current of phase C is positive and greater than a set threshold. If this condition is met, it indicates that the synchronization voltage of phase A and the input voltage of phase C correspond correctly.

[0057] If the A-phase synchronization voltage and the C-phase input voltage still do not correspond correctly, reverse the phases of all three-phase synchronization voltages and repeat the above steps.

[0058] The phase B synchronization voltage is multiplied by the phase B, phase C, and phase A currents of the chain SVG device, and the sum is calculated based on the number of sampling points in one fundamental cycle. If the sum of the product of the phase B synchronization voltage and the phase B current is positive and greater than a set threshold, it indicates that the phase B synchronization voltage and the phase B current are in phase, and the phase B synchronization voltage and the phase B input voltage correspond correctly. Otherwise, the phase B synchronization voltage and the phase B input voltage do not correspond.

[0059] If the phase B synchronization voltage and the phase B input voltage do not correspond correctly, then it is further determined whether the sum of the product of the phase B synchronization voltage and the phase C current is positive and greater than a set threshold. If it is satisfied, it indicates that the phase B synchronization voltage and the phase C input voltage correspond correctly; otherwise, they do not correspond.

[0060] If the phase B synchronization voltage and the phase C input voltage do not correspond correctly, then it is further determined whether the sum of the product of the phase B synchronization voltage and the phase A current is positive and greater than a set threshold. If it is satisfied, it indicates that the phase A synchronization voltage and the phase C input voltage correspond correctly.

[0061] Finally, the correspondence between the C-phase synchronization voltage and the input voltage of each phase was determined, and the corresponding line sequence relationship between the three-phase synchronization voltage and the three-phase input voltage was finally obtained.

[0062] In one specific embodiment, after step 5), a step 6) is included, adjusting the bus current offset angle so that the data displayed by the chain-type SVG device is consistent with the background or other data acquisition system, thereby correcting the phase difference between the three-phase bus current and the three-phase synchronization signal after phase sequence adjustment. The bus current offset angle is 0°, -120°, or +120°.

[0063] In one specific embodiment, in step 5), the specific process of allocating the three-phase modulation waves to the three-phase converter chains is as follows: if the A-phase synchronization voltage corresponds to the A-phase input voltage, then the calculated A-phase modulation wave is allocated to the A-phase converter chain; if the A-phase synchronization voltage corresponds to the B-phase input voltage, then the calculated A-phase modulation wave is allocated to the B-phase converter chain; if the A-phase synchronization voltage corresponds to the C-phase input voltage, then the calculated A-phase modulation wave is allocated to the C-phase converter chain; similarly, the B and C-phase modulation waves can be allocated to the converter chains of the corresponding line sequence. The modulation signals of each phase converter chain are superimposed with the correction values ​​of the modulation waves of each phase to generate the final modulation signal.

[0064] The present invention also discloses a phase sequence adaptive grid-connected control system for a chain-type SVG device, comprising:

[0065] The line-phase conversion module is used to obtain the three-phase line voltage input from the chain-type SVG device and calculate the three-phase phase voltage.

[0066] The phase sequence detection and adjustment module is used to take the three-phase phase voltage as the input of the software phase-locked loop and use the d-axis and q-axis components of the voltage output by the software phase-locked loop to determine the voltage phase sequence. If the voltage phase sequence is negative, any two phase voltages are swapped to adjust the three-phase voltage to positive sequence.

[0067] The recording module is used to acquire data on the three-phase current and three-phase synchronous voltage of the SVG during high-voltage closing.

[0068] The line sequence determination module is used to obtain the corresponding line sequence relationship between the three-phase synchronous voltage and the three-phase input voltage based on the data of the SVG three-phase current and three-phase synchronous voltage during high-voltage closing and charging.

[0069] The modulation signal calculation module is used to adjust the line sequence of the three-phase current acquisition signal output by the chain SVG device according to the corresponding line sequence relationship between the three-phase synchronous voltage and the three-phase input voltage, and further calculate the three-phase modulation wave, and then distribute the three-phase modulation wave to the three-phase converter chain accordingly.

[0070] The phase sequence adaptive grid-connected control system of the chain-type SVG device of the present invention, corresponding to the control method described above, also has the advantages described above.

[0071] The invention will be further described in detail below with reference to a specific embodiment:

[0072] 1. The line / phase conversion module calculates the three-phase phase voltage based on whether the SVG device is direct-connected or step-down, using the acquired three-phase line voltage. If it is direct-connected, the SVG input phase voltage lags the bus line voltage by 30°. a =(u ab -u ca ) / 3、u b =(u bc -u ab ) / 3、u c =(u ca -u bc ) / 3; If it is a step-down type, the SVG input phase voltage is in phase with the bus line voltage.

[0073] 2. The phase sequence judgment module uses the low-pass filtered values ​​of the d-axis and q-axis components of the voltage output by the software phase-locked loop to judge the voltage phase sequence. When the software phase-locked loop is stably locked, if the voltage phase sequence is positive, then Ud is basically a constant DC quantity and Uq is basically zero. If the voltage phase sequence is negative, then Uq is not zero and contains a second harmonic AC component. Based on this, if Ud is greater than the set threshold and Uq is less than the set threshold, the voltage phase sequence can be judged to be positive, and the phase sequence flag Seq_Flag = 0. Otherwise, the voltage phase sequence is negative, and the phase sequence flag Seq_Flag = 1.

[0074] 3. The phase sequence adjustment module adjusts the values ​​of the three-phase voltages based on the phase sequence flag. If Seq_Flag = 0, then u... A =u a u B =u b u C =u c If Seq_Flag = 1, in principle, the three-phase voltage can be adjusted to positive sequence by swapping any two phase voltages. For simplicity, let u A =u b u B =u a u C =u c ;

[0075] 4. Data recording module: When the high voltage of the SVG branch is closed, the module records the values ​​of the three-phase charging current and the three-phase synchronous phase voltage of the SVG. When the control system detects that the circuit breaker of the SVG branch is closed and the value of the charging current of any phase is greater than the set threshold, the data recording flag is set. The sampling frequency of the control system is 6.4kHz, that is, 128 points are sampled per power frequency cycle. Six arrays with a data width of 128 can be defined to record the values ​​of the three-phase charging current and the three-phase synchronous phase voltage of the SVG.

[0076] 5. The line sequence judgment module judges the line sequence based on the data recorded by the data recording module. Since the three-phase charging current is active current during SVG pre-charging, it is in phase with the input voltage of the three phases A, B, and C respectively. Therefore, the input voltage sequence can be determined by judging whether the charging current is in phase with the synchronization voltage. The specific method is as follows: multiply the phase A synchronization voltage by the charging currents of phases A, B, and C of the SVG respectively and perform a 128-point summation. If the cumulative sum of the products of the phase A synchronization voltage and the phase A current is positive and greater than a set threshold, it indicates that the phase A synchronization voltage and the phase A current are in phase, and the phase A synchronization voltage and the phase A input voltage correspond correctly, PhaseA_Flag = 1; if the cumulative sum of the products of the phase A synchronization voltage and the phase A current does not meet the condition, further judge whether the cumulative sum of the products of the phase A synchronization voltage and the phase B current meets the set condition. If it does, it indicates that the phase A synchronization voltage and the phase B input voltage correspond correctly, PhaseA_Flag = 2; if the cumulative sum of the products of the phase A synchronization voltage and the phase B current does not meet the condition, further judge whether the cumulative sum of the products of the phase A synchronization voltage and the phase C current meets the set condition. If it does, it indicates that the phase A synchronization voltage and the phase C input voltage correspond correctly, PhaseA_Flag = 3.

[0077] 6. If the synchronization voltage of phase A and the input voltage of phase C are still not correctly matched, reverse the phases of all three-phase synchronization voltages and repeat step 5 above.

[0078] 7. After the A-phase line sequence judgment is completed, based on the value of PhaseA_Flag, continue to judge the B-phase line sequence. If PhaseA_Flag = 1, multiply the B-phase synchronization voltage by the B and C-phase currents of the SVG respectively and perform a 128-point summation calculation. If the cumulative sum of the B-phase synchronization voltage and B-phase current meets the set condition, it indicates that the B-phase synchronization voltage and B-phase input voltage correspond correctly, and PhaseB_Flag = 2. If the cumulative sum of the B-phase synchronization voltage and B-phase current does not meet the condition, further judge whether the cumulative sum of the B-phase synchronization voltage and C-phase current meets the set condition. If it does, it indicates that the B-phase synchronization voltage and C-phase input voltage correspond correctly, and PhaseB_Flag = 3. If PhaseA_Flag = 2, multiply the B-phase synchronization voltage by the A and C-phase currents of the SVG respectively and perform a 128-point summation calculation. If the cumulative sum of the B-phase synchronization voltage and A-phase current meets the set condition, it indicates that the B-phase synchronization voltage and C-phase input voltage correspond correctly, and PhaseB_Flag = 3. If the voltage and the A-phase input voltage correspond correctly, PhaseB_Flag = 1. If the sum of the product of the B-phase synchronous voltage and the A-phase current does not meet the condition, further determine whether the sum of the product of the B-phase synchronous voltage and the C-phase current meets the set condition. If it does, it indicates that the B-phase synchronous voltage and the C-phase input voltage correspond correctly, and PhaseB_Flag = 3. If PhaseA_Flag = 3, multiply the B-phase synchronous voltage by the B and A-phase currents of the SVG respectively and perform a 128-point summation calculation. If the sum of the product of the B-phase synchronous voltage and the B-phase current meets the set condition, it indicates that the B-phase synchronous voltage and the B-phase input voltage correspond correctly, and PhaseB_Flag = 2. If the sum of the product of the B-phase synchronous voltage and the B-phase current does not meet the condition, further determine whether the sum of the product of the B-phase synchronous voltage and the A-phase current meets the set condition. If it does, it indicates that the B-phase synchronous voltage and the A-phase input voltage correspond correctly, and PhaseB_Flag = 1.

[0079] 8. After determining the line sequence relationship of the input voltages of phases A and B, the line sequence value of the input voltage of phase C can be calculated, as shown in Table 1.

[0080] Table 1 Line Sequence Flag Values

[0081] 1 2 3 1 3 2 2 1 3 2 3 1 3 2 1 3 1 2

[0082] 9. The wiring sequence adjustment module adjusts the values ​​of the SVG three-phase current samples entering the current closed-loop control module based on the wiring sequence flag value. For phase A, if PhaseA_Flag = 1, then i A =i a If PhaseA_Flag = 2, then i A =i b If PhaseA_Flag = 3, then i A =i cFor phase B, if PhaseB_Flag = 1, then i B =i a If PhaseB_Flag = 2, then i B =i b If PhaseB_Flag = 3, then i B =i c For phase C, if PhaseC_Flag = 1, then i C =i a If PhaseC_Flag = 2, then i C =i b If PhaseC_Flag = 3, then i C =i c ;

[0083] 10. The current closed-loop control module implements the reactive power and harmonic compensation algorithm, performs closed-loop control on the SVG output current, and generates a three-phase modulation signal.

[0084] 11. The three-phase modulation signal calculation module redistributes the three-phase modulation signals calculated and output by the current closed-loop control module based on the line sequence flag value. For phase A, if PhaseA_Flag = 1, the calculated phase A debugging wave is allocated to the phase A commutator chain; if PhaseA_Flag = 2, the phase A debugging wave is allocated to the phase B commutator chain; if PhaseA_Flag = 3, the phase A debugging wave is allocated to the phase C commutator chain. Similarly, the phase B and phase C modulation waves can be allocated to the commutator chains with the corresponding line sequence. The modulation signals of each phase commutator chain are superimposed with the modulation wave correction values ​​output by the DC voltage equalization control module of each phase to generate the final modulation signal.

[0085] 12. Since the phase sequence adjustment module only swaps the A and B phase voltages to achieve phase sequence adjustment when the voltage is in negative sequence, there may be a phase difference between the three-phase synchronization signal after phase sequence adjustment and the actual bus synchronization signal. This phase difference is -120° or +120°, which will affect the bus reactive power calculation and thus affect the automatic reactive power compensation. Therefore, it is necessary to compare the bus power data with the background or other data acquisition systems and adjust the bus current offset angle (0°, -120° or +120°) so that the bus power data displayed on the SVG device interface is consistent with the background or other data acquisition systems, thereby correcting the phase difference between the bus three-phase current and the three-phase synchronization signal after phase sequence adjustment.

[0086] 13. After the above steps, the phase sequence adaptive grid-connected operation of the SVG device can be achieved.

[0087] This invention also discloses a computer-readable storage medium storing a computer program. When executed by a processor, the computer program performs the steps of the phase sequence adaptive grid-connected control method for a chain-type SVG device as described above. This invention further discloses a computer device including a memory and a processor. The memory stores a computer program, which, when executed by a processor, performs the steps of the phase sequence adaptive grid-connected control method for a chain-type SVG device as described above. This invention can implement all or part of the processes in the methods of the above embodiments, or it can be implemented by a computer program instructing related hardware. The computer program can be stored in a computer-readable storage medium, and when executed by a processor, it can implement the steps of the various method embodiments described above. The computer program includes computer program code, which can be in the form of source code, object code, executable files, or certain intermediate forms. The computer-readable medium can include: any entity or device capable of carrying computer program code, a recording medium, a USB flash drive, a portable hard drive, a magnetic disk, an optical disk, a computer memory, a read-only memory (ROM), a random access memory (RAM), an electrical carrier signal, a telecommunication signal, and a software distribution medium, etc. Memory can be used to store computer programs and / or modules. The processor performs various functions by running or executing the computer programs and / or modules stored in the memory, and by accessing data stored in the memory. Memory may include high-speed random access memory, and may also include non-volatile memory, such as hard disks, RAM, plug-in hard disks, smart media cards (SMC), secure digital cards (SD), flash cards, at least one disk storage device, flash memory device, or other volatile solid-state storage devices.

[0088] The above are merely preferred embodiments of the present invention. The scope of protection of the present invention is not limited to the above embodiments. All technical solutions falling within the scope of the present invention's concept are within the scope of protection of the present invention. It should be noted that for those skilled in the art, any improvements and modifications made without departing from the principles of the present invention should be considered within the scope of protection of the present invention.

Claims

1. A phase sequence adaptive grid-connected control method for a chain-type SVG device, characterized in that, Including the following steps: 1) Obtain the three-phase line voltage input from the chain-type SVG device and calculate the three-phase phase voltage synchronization signal; 2) Use the three-phase voltage as the input of the software phase-locked loop, and use the d-axis and q-axis components of the voltage output by the software phase-locked loop to determine the voltage phase sequence. If the voltage phase sequence is negative, swap any two phase voltages to adjust the three-phase voltage to positive sequence. 3) Obtain data on the three-phase current and three-phase synchronous voltage of the SVG during high-voltage closing; 4) Based on the data of the three-phase current and three-phase synchronous voltage of the SVG during high-voltage closing and charging, the corresponding line sequence relationship between the three-phase synchronous voltage and the three-phase input voltage is obtained; 5) Based on the corresponding line sequence relationship between the three-phase synchronous voltage and the three-phase input voltage, the line sequence of the three-phase current acquisition signal output by the chain SVG device is adjusted, the three-phase modulation wave is calculated, and the three-phase modulation wave is correspondingly allocated to the three-phase converter chain. In step 4), the phase synchronization voltage is multiplied by each phase current and summed according to the number of sampling points in one fundamental cycle. If the sum of the products of the phase synchronization voltage and one phase current is positive and greater than a set threshold, it indicates that the phase synchronization voltage is in phase with the phase input voltage. The specific process of step 4) is as follows: The A-phase synchronization voltage is multiplied by the A, B, and C phase currents output by the chain SVG device, and the sum is calculated based on the number of sampling points in one fundamental cycle. If the sum of the multiplication of the A-phase synchronization voltage and the A-phase current is positive and greater than a set threshold, it indicates that the A-phase synchronization voltage and the A-phase current are in phase, and the A-phase synchronization voltage and the A-phase input voltage correspond correctly. Otherwise, the A-phase synchronization voltage and the A-phase input voltage do not correspond. If the phase A synchronization voltage and phase A input voltage do not correspond correctly, then it is further determined whether the sum of the product of phase A synchronization voltage and phase B current is positive and greater than a set threshold. If it is satisfied, it indicates that phase A synchronization voltage and phase B input voltage correspond correctly; otherwise, they do not correspond. If the synchronization voltage of phase A and the input voltage of phase B do not correspond correctly, then it is further determined whether the sum of the product of the synchronization voltage of phase A and the current of phase C is positive and greater than a set threshold. If it is satisfied, it indicates that the synchronization voltage of phase A and the input voltage of phase C correspond correctly. If the phase A synchronization voltage and the phase C input voltage are still not correctly matched, reverse the phases of all three phase synchronization voltages and repeat the above steps; The phase B synchronization voltage is multiplied by the three phase B, C, and A currents output by the chain SVG device, and the sum is calculated based on the number of sampling points in one fundamental cycle. If the sum of the multiplication of the phase B synchronization voltage and the phase B current is positive and greater than a set threshold, it indicates that the phase B synchronization voltage and the phase B current are in phase, and the phase B synchronization voltage and the phase B input voltage correspond correctly. Otherwise, the phase B synchronization voltage and the phase B input voltage do not correspond. If the phase B synchronization voltage and the phase B input voltage do not correspond correctly, then it is further determined whether the sum of the product of the phase B synchronization voltage and the phase C current is positive and greater than a set threshold. If it is satisfied, it indicates that the phase B synchronization voltage and the phase C input voltage correspond correctly; otherwise, they do not correspond. If the phase B synchronization voltage and the phase C input voltage do not correspond correctly, then it is further determined whether the cumulative sum of the product of the phase B synchronization voltage and the phase A current is positive and greater than a set threshold. If it is satisfied, it indicates that the phase B synchronization voltage and the phase A input voltage correspond correctly. Finally, the correspondence between the C-phase synchronization voltage and the input voltage of each phase was determined, and the corresponding line sequence relationship between the three-phase synchronization voltage and the three-phase input voltage was finally obtained.

2. The phase sequence adaptive grid-connected control method for the chain-type SVG device according to claim 1, characterized in that, After step 5), step 6) is also included to adjust the bus current offset angle, thereby correcting the phase difference between the three-phase bus current and the three-phase synchronization signal after phase sequence adjustment.

3. The phase sequence adaptive grid-connected control method for the chain-type SVG device according to claim 2, characterized in that, The bus current offset angle is 0°, -120°, or +120°.

4. The phase sequence adaptive grid-connected control method for a chain-type SVG device according to claim 1, 2, or 3, characterized in that, In step 5), the specific process of allocating the three-phase modulation waves to the three-phase converter chains is as follows: if the A-phase synchronization voltage corresponds to the A-phase input voltage, then the calculated A-phase modulation wave is allocated to the A-phase converter chain; if the A-phase synchronization voltage corresponds to the B-phase input voltage, then the calculated A-phase modulation wave is allocated to the B-phase converter chain; if the A-phase synchronization voltage corresponds to the C-phase input voltage, then the calculated A-phase modulation wave is allocated to the C-phase converter chain; similarly, the B and C-phase modulation waves can be allocated to the converter chains of the corresponding line sequence.

5. The phase sequence adaptive grid-connected control method for the chain-type SVG device according to claim 4, characterized in that, In step 5), the modulation signals of each phase commutator chain are superimposed with the modulation wave correction values ​​of each phase to generate the final modulation signal.

6. The phase sequence adaptive grid-connected control method for a chain-type SVG device according to claim 1, 2, or 3, characterized in that, In step 1), it is determined whether the chain-type SVG device is a direct-connected type or a step-down type. The three-phase phase voltage is calculated from the acquired three-phase line voltage. If it is a direct-connected type, the input phase voltage of the chain-type SVG device lags behind the bus line voltage by 30°. a =(u ab -u ca ) / 3、u b =(u bc -u ab ) / 3、u c =(u ca -u bc ) / 3; If it is a step-down type, the SVG input phase voltage is in phase with the bus line voltage, u a =u ab / u b =u bc / u c =u ca / .

7. A phase sequence adaptive grid-connected control system for a chain-type SVG device, used to execute the steps of the phase sequence adaptive grid-connected control method for a chain-type SVG device as described in any one of claims 1 to 6, characterized in that, include: The line-phase conversion module is used to obtain the three-phase line voltage input from the chain-type SVG device and calculate the three-phase phase voltage. The phase sequence detection and adjustment module is used to take the three-phase voltage as the input of the software phase-locked loop and use the d-axis and q-axis components of the voltage output by the software phase-locked loop to determine the voltage phase sequence; if the voltage phase sequence is negative, any two phase voltages are swapped to adjust the three-phase voltage to positive sequence. The recording module is used to acquire data on the three-phase current and three-phase synchronous voltage of the SVG during high-voltage closing. The line sequence determination module is used to obtain the corresponding line sequence relationship between the three-phase synchronous voltage and the three-phase input voltage based on the data of the SVG three-phase current and three-phase synchronous voltage during high-voltage closing and charging. The modulation signal calculation module is used to adjust the line sequence of the three-phase current acquisition signal output by the chain SVG device according to the corresponding line sequence relationship between the three-phase synchronous voltage and the three-phase input voltage, calculate the three-phase modulation wave, and allocate the three-phase modulation wave to the three-phase converter chain.

8. A computer-readable storage medium having a computer program stored thereon, characterized in that, The computer program, when run by the processor, executes the steps of the phase sequence adaptive grid-connected control method for the chain SVG device as described in any one of claims 1 to 6.

9. A computer device comprising a memory and a processor, wherein the memory stores a computer program, characterized in that, The computer program, when run by the processor, executes the steps of the phase sequence adaptive grid-connected control method for the chain SVG device as described in any one of claims 1 to 6.

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