CN113659447B - Method for automatically correcting sampling polarity of series-connection side voltage of in-phase power supply device - Google Patents

Method for automatically correcting sampling polarity of series-connection side voltage of in-phase power supply device Download PDF

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Publication number
CN113659447B
CN113659447B CN202110821432.9A CN202110821432A CN113659447B CN 113659447 B CN113659447 B CN 113659447B CN 202110821432 A CN202110821432 A CN 202110821432A CN 113659447 B CN113659447 B CN 113659447B
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China
Prior art keywords
voltage
cabinet
seat
switch cabinet
sampling
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CN202110821432.9A
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CN113659447A (en
Inventor
刘刚
陈旭东
高洪
宋晓梅
翟超
赵小虎
陈雪
许恩泽
黄辉
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Xuji Group Co Ltd
XJ Electric Co Ltd
Xian XJ Power Electronics Technology Co Ltd
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Xuji Group Co Ltd
XJ Electric Co Ltd
Xian XJ Power Electronics Technology Co Ltd
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Classifications

    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02B—BOARDS, SUBSTATIONS OR SWITCHING ARRANGEMENTS FOR THE SUPPLY OR DISTRIBUTION OF ELECTRIC POWER
    • H02B1/00—Frameworks, boards, panels, desks, casings; Details of substations or switching arrangements
    • H02B1/24—Circuit arrangements for boards or switchyards
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J7/00—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
    • H02J7/007—Regulation of charging or discharging current or voltage
    • H02J7/00712—Regulation of charging or discharging current or voltage the cycle being controlled or terminated in response to electric parameters
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J7/00—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
    • H02J7/34—Parallel operation in networks using both storage and other dc sources, e.g. providing buffering
    • H02J7/345—Parallel operation in networks using both storage and other dc sources, e.g. providing buffering using capacitors as storage or buffering devices
    • 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
    • H02M5/00—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases
    • H02M5/40—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases with intermediate conversion into dc
    • H02M5/42—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases with intermediate conversion into dc by static converters
    • H02M5/44—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases with intermediate conversion into dc by static converters using discharge tubes or semiconductor devices to convert the intermediate dc into ac
    • H02M5/453—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases with intermediate conversion into dc by static converters using discharge tubes or semiconductor devices to convert the intermediate dc into ac using devices of a triode or transistor type requiring continuous application of a control signal
    • H02M5/458—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases with intermediate conversion into dc by static converters using discharge tubes or semiconductor devices to convert the intermediate dc into ac using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only
    • H02M5/4585—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases with intermediate conversion into dc by static converters using discharge tubes or semiconductor devices to convert the intermediate dc into ac using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only having a rectifier with controlled elements
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J2207/00—Indexing scheme relating to details of circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
    • H02J2207/50—Charging of capacitors, supercapacitors, ultra-capacitors or double layer capacitors

Abstract

The invention provides an in-phase power supply serial side voltage sampling polarity automatic correction method. According to the method, the in-phase power supply device is operated to precharge and output an open-loop voltage flow, the polarity of the PT voltage sampling signal of the incoming line switch cabinet is automatically corrected according to the PT voltage sampling signals of the starting cabinet and the incoming line switch cabinet, and the voltage after the polarity is used in control, so that the voltage polarity output by the in-phase power supply device at the serial side is ensured to be matched with the voltage (T seat voltage) of the incoming line switch cabinet, and the overcurrent problem caused by the opposite output voltage of the converter and the incoming line voltage is avoided. The invention provides a method for judging the sampling direction twice in the automatic correction process of the sampling polarity of the voltage at the serial side, which is simple and effective. In the process of judging the polarity twice, the invention can also find out the situation that the sampling polarities are not opposite and are different due to the error of setting the sampling coefficient and the like.

Description

Method for automatically correcting sampling polarity of series-connection side voltage of in-phase power supply device
Technical Field
The invention relates to the technical field of power electronics, in particular to an automatic correction method for sampling polarity of series-connected side voltage of an in-phase power supply device.
Background
The electric locomotive is a single-phase electric load, in order to reduce the influence of negative sequence current on an electric system, measures such as split-phase partition, rotation phase sequence and the like are adopted for traction network power supply, and an electric split-phase link is added in the overhead line system. The automatic passing neutral section device has the advantages of frequent action, short service life and low reliability, and can cause the loss of train speed and traction force. The in-phase power supply device solves the problems of electric phase separation, voltage fluctuation, low power factor, exceeding of negative sequence current and the like in the traction substation.
The in-phase power supply device mainly comprises a traction matching transformer and an in-phase power supply converter, wherein the traction matching transformer is a multi-winding transformer, and the in-phase power supply converter comprises a plurality of power units in series-parallel connection and comprises a parallel connection side and a series connection side. The high-voltage side of the traction matching transformer is connected with the traction transformer M seat, the low-voltage side of the traction matching transformer is connected with the parallel side of the in-phase power supply converter, and the serial side of the converter is connected into the traction transformer T seat through the starting cabinet.
The positive direction of voltage sampling of the T seat of the transformer is very important for controlling the serial side of the in-phase power supply device, if the voltage sampling direction of the T side is incorrect, variable errors such as phase locking, feedforward and the like of the serial side can occur, the situation that voltage and current cannot be effectively controlled can even occur, when the serial side outputs the maximum positive voltage and the T seat is just the maximum negative voltage, the double voltage is added to the reactor of the starting cabinet, instantaneous heavy current occurs, and the power switching device of the serial side can be damaged.
At present, the converter is connected with an external incoming line, PT signals sent by a switch cabinet are used, all parties generally communicate with each other to agree with the positive direction in a design stage, and the positive direction is definitely sampled in a line checking mode and a channel relay protection tester signal adding mode in a field early-stage installation and debugging stage.
The prior art scheme can determine the direction, but has the problem that manual line checking is time-consuming and labor-consuming. In addition, although the sampling direction of the voltage of the T seat of the in-phase power supply device is tested to be correct by using the relay protection tester, the wiring error of the main loop can also occur, and the problem that the output voltage of the serial side is opposite to the voltage of the T seat can also occur.
Disclosure of Invention
Aiming at the defects of the prior art, the invention provides an automatic correction method for the voltage sampling polarity of a T seat of an in-phase power supply device, which operates the in-phase power supply device to precharge and output an open loop voltage flow, automatically corrects the polarity of a PT voltage sampling signal of a wire inlet switch cabinet according to PT voltage sampling signals of a starting cabinet and the wire inlet switch cabinet, uses the voltage after the polarity correction in control, ensures that the voltage polarity output by a serial side of the in-phase power supply device is matched with the voltage of the T seat, and avoids the overcurrent problem caused by the opposite of the output voltage of a converter and the wire inlet voltage.
In order to achieve the above purpose, the invention provides an in-phase power supply series side voltage sampling polarity automatic correction method, which comprises the following steps:
the in-phase power supply device is precharged by the incoming line of a circuit breaker at the serial side of the incoming line switch cabinet and a starting circuit of the starting cabinet; during the precharge period, collecting and judging a voltage sampling signal of the T-seat incoming line switch cabinet PT and a voltage signal of the starting cabinet PT, and recording a first FLAG FLAG1 as invalid if the two voltage sampling directions are the same, otherwise, judging as valid;
after the precharge is finished, disconnecting a circuit breaker at the serial side in the T-seat incoming line switch cabinet, generating open-loop modulation waves according to the phase angle of PT voltage of the T-seat incoming line switch cabinet, and outputting open-loop voltage at the serial side;
comparing whether the phase of open-loop voltage of the starting cabinet PT is the same as the direction of a PT signal of the T-seat incoming line switch cabinet, if so, recording that the second FLAG FLAG2 is invalid, otherwise, the second FLAG FLAG2 is valid;
if one of the first FLAG1 and the second FLAG2 is valid and the other is invalid, the voltage signal of the sampling PT of the incoming line switch cabinet of the T seat is inverted to be used as the signal for actual control, otherwise, the voltage sampling polarity is not required to be corrected.
Further, the in-phase power supply device comprises a power cabinet, a starting cabinet, a T-seat incoming line switch cabinet, a traction matching transformer and an outgoing line switch cabinet;
the power cabinet comprises a plurality of power units for power conversion, the serial side H bridge of each power unit is connected with the starting cabinet after being connected in series, and the parallel side of each power unit is connected with the outgoing switch cabinet through a traction matching transformer respectively;
the outgoing line switch cabinet is connected with the power grid transformer M seat;
the starting cabinet comprises a soft start contactor KM1, a soft start resistor and a main contactor KM2, wherein the soft start resistor and the soft start contactor KM1 are connected in series and then connected in parallel with the main contactor;
the starting cabinet is connected with the T-seat incoming line switch cabinet, and the T-seat incoming line switch cabinet is connected with the T-seat of the power grid transformer.
Further, during precharge, a voltage sampling signal of the T-seat incoming line switch cabinet PT and a voltage signal of the PT in the starting cabinet are collected and judged, and the method comprises the following steps: defining the per unit value of the PT sampling instantaneous voltage of the T-seat incoming line switch cabinet as u T Starting cabinet PT samples instantaneous voltage per unit value as uQ, and calculates two voltage sampling instantaneous difference delta u=u T -u Q If the effective value DeltaU of Deltau RMS If the voltage is smaller than 0.3pu, the voltage sampling directions are considered to be the same, and the first FLAG FLAG1 is recorded as invalid; if the effective value DeltaU of Deltau RMS If the voltage is greater than 1.6pu, the voltage sampling directions are considered to be different, and a first FLAG FLAG1 is recorded as effective; if the effective value DeltaU of Deltau RMS Between 0.3pu and 1.6pu, the fault is shut down.
Further, the pre-charging process includes closing a soft start contactor KM1 of a starting loop in the starting cabinet, closing a breaker QF in the T-seat incoming line switch cabinet, when the direct current bus capacitor of the power unit is charged to reach a set value, closing a main contactor KM2 of the starting loop, and opening the soft start contactor KM1.
Further, after the precharge is completed and the T-seat incoming line switch cabinet breaker QF is disconnected, an open-loop modulation wave is generated according to the phase angle of the T-seat incoming line switch cabinet PT voltage, and an open-loop voltage is output from the serial side, including:
PT voltage sampling u of T-seat incoming line switch cabinet T Phase locking is carried out, and the phase angle omega of the voltage of the T-seat incoming line switch cabinet obtained by phase locking T t, u mod ＝U open sin(ω T t) is given as an open loop modulated wave, where U open And for the set open-loop modulation degree, the direct-current voltage pre-charged by the direct-current bus capacitor is used for open-loop pulse transmission, and the voltage is output at the serial side port and the starting cabinet.
Further, comparing whether the phase of the open-loop voltage sampled by the starting cabinet PT is the same as the direction of the voltage signal of the T-seat incoming line switch cabinet PT, including:
the voltage sampled by the starting cabinet PT during the current open loop pulse sending is u Q_open For u Q_open Phase locking is carried out to obtain phase angle omega Qo t；
Phase angle omega of T-seat voltage obtained by phase locking T t and phase angle omega Qo t is differenced and takes the absolute value: Δθ= |ω T t-ω Qo I (I); if Δθ is greater than pi, the process yields θ in the range of 0 to pi FLAG2 The method comprises the steps of carrying out a first treatment on the surface of the If theta is FLAG2 Less thanJudging that the open-loop voltage of the starting cabinet is in phase with the voltage of the T seat, and setting a second FLAG FLAG2 as invalid; if the difference value is, θ FLAG2 Is greater than->Judging that the open-loop voltage of the starting cabinet is opposite to the T seat voltage, and setting a second FLAG FLAG2 to be effective; if theta is FLAG2 Between->And->And (5) stopping the machine when the machine fails.
Further, if no fault occurs, 0 indicates invalid, 1 indicates valid, and the first FLAG1 and the second FLAG2 are xored, and the operation result is defined as FLAG3:
if FLAG3 is 0, the voltage sampling polarity does not need to be corrected; if FLAG3 is 1, the PT voltage acquisition signal u of the T-seat incoming line switch cabinet is required T Multiplied by (-1) and then used as a signal for control.
Further, if Δθ is greater than pi, the process yields θ in the range of 0 to pi FLAG2 Comprising: if the angle is greater than pi, θ FLAG2 ＝2π-|Δθ|。
The technical scheme of the invention has the following beneficial technical effects:
(1) The method for automatically correcting the sampling polarity of the voltage at the serial side of the in-phase power supply device can omit complicated line checking steps, quickly and reliably correct the sampling, and avoid the problem that the output voltage of the converter is opposite to the incoming line voltage due to the error of the voltage sampling direction.
(2) In the process of judging the polarity twice, the invention can also find out the situation that the sampling polarities are not opposite and are different due to the error of setting the sampling coefficient and the like.
Drawings
FIG. 1 is a topological structure diagram of an in-phase power supply;
FIG. 2 is a flow chart of a method for automatically correcting the voltage polarity at the serial side of the in-phase power supply device.
Detailed Description
The objects, technical solutions and advantages of the present invention will become more apparent by the following detailed description of the present invention with reference to the accompanying drawings. It should be understood that the description is only illustrative and is not intended to limit the scope of the invention. In addition, in the following description, descriptions of well-known structures and techniques are omitted so as not to unnecessarily obscure the present invention.
The invention provides an automatic correction method for voltage polarity of a serial side of an in-phase power supply device, which is shown in figure 1 and comprises a power cabinet, a starting cabinet, a T-seat incoming line switch cabinet, a traction matching transformer and an outgoing line switch cabinet.
The power cabinet comprises n power units, one sides of the power units are connected in parallel, one sides of the power units are connected in series, and the serial sides of the power units are connected with the starting cabinet.
The starting cabinet comprises an output reactor L, a starting loop and a sampling PT in the starting cabinet. The other end of the starting cabinet is connected with the T-seat incoming line switch cabinet.
The T-seat incoming line switch cabinet comprises a serial side breaker QF and a voltage sampling PT.
Further, the power unit includes a parallel side H-bridge, a dc bus capacitor, and a serial side H-bridge, where the parallel side is provided with a module grid-connected contactor KM3_i (i is a power module serial number), and the serial side is provided with a bypass switch PLi (i is a power module serial number), and after the serial side H-bridges of the plurality of power units are connected in series, the power unit is connected to the starting cabinet.
Further, the starting cabinet comprises an output reactor L which is used for limiting rapid change of current and filtering higher voltage harmonic waves. The starting circuit of the starting cabinet comprises a soft start contactor KM1, a soft start resistor and a main contactor KM2, and is used for limiting the charging current of the power unit through the soft start resistor and the soft start contactor KM1, the main contactor is connected with the soft start contactor KM1 and the soft start resistor in parallel in series, the purpose of bypassing the soft start resistor is achieved, and the energy consumption and the voltage drop of the soft start resistor are avoided during operation.
In order to achieve the purpose of automatic correction of the polarity of the T-pad voltage sampling, referring to fig. 2, the present invention includes the following steps:
(1) The in-phase power supply device is used for precharging the incoming line of a starting loop of the starting cabinet through a circuit breaker at the serial side of the T-seat incoming line switch cabinet; during the precharge period, a voltage sampling signal from the T-seat incoming line switch cabinet PT and a voltage signal from the PT in the starting cabinet are collected simultaneously. If the two voltage sampling directions are the same, the first mark 1 is recorded to be invalid, otherwise, the first mark 1 is recorded to be valid.
Further, the pre-charging process includes closing a soft start contactor KM1 of a starting loop in the starting cabinet, closing a breaker QF in the T-seat incoming line switch cabinet, when the direct current bus capacitor of the power unit is charged to reach a set value, closing a main contactor KM2 of the starting loop, and opening the soft start contactor KM1.
Further, the two voltage sampling directions are compared, the method is that the real values of the two sampling directions are subjected to difference, the difference is judged with the effective value of the voltage difference, if the effective value of the difference is small, the voltage sampling directions are considered to be the same, the setting flag1 is 0 (invalid), and if the effective value of the difference is large, the voltage sampling directions are considered to be opposite, and the setting flag1 is 1 (valid).
Defining the per unit value of the PT sampling instantaneous voltage of the T-seat incoming line switch cabinet as u T The PT sampling instantaneous voltage per unit value of the starting cabinet is u Q . Because the main loop is connected when the T-seat incoming line switch cabinet circuit breaker is closed, the voltages acquired by the two PT should have the same amplitude and the same or opposite phases. Judging whether the directions of the two sampling points are consistent or not, judging by using a per unit instantaneous value subtraction mode, and defining two voltage sampling instantaneous difference delta u=u T -u Q If the effective value DeltaU of Deltau RMS If the effective value is smaller than 0.3pu, the two sampling directions are considered to be the same, the set first FLAG1 (FLAG 1) is set to be invalid (0), if the effective value of Deltau is larger than 1.6pu, FLAG1 is set to be valid (1), and if the effective value of Deltau is between the two, the PT or the sampling circuit or the sampling gain is considered to be set to be wrong, and the fault is reported to be stopped.
If a failed shutdown condition does not occur, step (2) is continued.
In the pre-charging stage, the method not only completes the task of charging the direct-current bus of the power unit, but also compares the voltage directions of the T-seat incoming line switch cabinet PT and the starting cabinet PT when the main loop is communicated. The comparison is to record the difference of sampling directions when PT at two places collect the same primary voltage.
(2) And after the precharge is finished, disconnecting the circuit breaker at the serial side in the T-seat incoming line switch cabinet, generating a modulation wave according to the phase angle of the voltage sampling signal of the PT-seat incoming line switch cabinet, and outputting open-loop voltage at the serial side.
Further, the output open-loop voltage is the phase-locked phase angle of the voltage sampled by the T-seat incoming line switch cabinet PT, and is used as the phase of the open-loop modulation wave, the amplitude can be set, and the modulation degree is defaulted to 50%.
After the pre-charging is finished, the circuit breaker at the inner serial side of the T-seat wire inlet switch cabinet is disconnected, and a main contactor in the starting cabinet is kept in a closing state, at the moment, the T-seat wire inlet switch cabinet is disconnected with a main loop of the starting cabinet, and PT of the starting cabinet is not related to PT in the wire inlet switch cabinet.
PT voltage sampling u of incoming line switch cabinet using T seat on control T Phase locking, using phase angle omega of phase locked T-base voltage T t, u mod ＝U open sin(ω T t) is given as an open loop modulated wave, where U open In order to set open-loop modulation degree, the direct-current voltage pre-charged by the direct-current bus capacitor is used for open-loop pulsing, and voltage is output at the serial side port.
The voltage signal output when the open loop pulse is sent out is sampled by using the start-up cabinet PT. Defining the voltage sampled by the starting cabinet PT at the time of opening the current pulse to be u Q_open For u Q_open Phase locking is carried out to obtain phase angle omega Qo t。
(3) And comparing whether the phase of open-loop voltage acquired by the starting cabinet PT is opposite to the direction of the PT signal of the T-seat incoming line switch cabinet. If the directions are the same, the second flag2 is recorded as invalid, otherwise, is valid.
When the open-loop voltage is output, the phase cannot be judged by using a mode of solving an effective value by using a difference because the actual values of the two voltages are different. And (3) phase locking is carried out on the sampled voltage of the starting cabinet PT, the phase locking angle of the sampled voltage of the starting cabinet PT and the sampled voltage phase locking angle of the T-seat incoming line switch cabinet PT are differed, if the difference value is small, the second mark 2 is set to 0 (invalid), and if the difference value is close to 180 degrees, the second mark 2 is set to 1 (valid).
During the period of outputting the open-loop voltage, the voltage difference value cannot be used as the basis because the voltage amplitude of the open-loop voltage at the serial side is unequal to that of the switch cabinet. During the period, the voltage sampling direction is judged according to the phase angle difference of the two voltage samples. The sampling direction is considered the same if the phase angle difference is around 0 degrees and the opposite direction is considered if it is around 180 degrees. Because the range of the phase angle difference delta theta is +/-2 pi, the absolute value delta theta I is firstly calculated, and the range is limited to 0 to +2pi; if the angle is greater than pi, θ FLAG2 =2pi- |Δθ| if the range is limited to 0 to pi, the angle difference θ is finally determined FLAG2 It is possible to judge whether it is close to pi or close to 0 more conveniently. If the angle difference is neither close to 0 nor pi, other faults are considered to occur, and shutdown inspection is required.
In one embodiment, the phase angle omega of the T-seat incoming line switch cabinet voltage (T-seat voltage) obtained by sampling the PT voltage of the T-seat incoming line switch cabinet T t and open loop pulsing start tank voltage phase angle omega Qo t is differenced and takes the absolute value: |Δθ=ω T t-ω Qo I, converting the difference range to a range of 0 to 2pi. If |Δθ| is greater than pi, the re-process is performed to process the angle difference in the range of 0 to pi. θ FLAG2 Less thanJudging that the open-loop voltage of the starting cabinet is in phase with the voltage of the T seat, and setting a set FLAG2 (FLAG 2) to be invalid; if the difference value is, θ FLAG2 Is greater than->Judging that the open-loop voltage of the starting cabinet is opposite to the T seat voltage, and setting the set second mark 2 (FLAG 2) to be valid; if the phase angle difference is between the two, the output pulse or sampling link is considered to be problematic, and the machine is stopped when the problem is reported.
After the precharge is finished, the T-seat incoming line switch breaker is disconnected, an open-loop modulation wave is output by using a phase-locked angle of PT voltage sampling of the T-seat incoming line switch cabinet, and the open-loop voltage output by the PT sampling serial side of the cabinet is started. And comparing the voltage sampling direction of the current starting cabinet PT with the voltage sampling direction of the incoming line switch cabinet PT. This comparison is to determine the relationship between the voltage output on the series side and the switch cabinet voltage when the signal of the switch cabinet PT is used as control.
(4) If one of the first flag1 and the second flag2 is valid and the other is invalid, the signal of the sampling PT of the T-seat switch cabinet is required to be inverted and used as the signal for actual control. Otherwise the voltage sampling polarity need not be corrected.
Furthermore, the exclusive or operation is performed on the first flag1 and the second flag2 obtained in the steps 1 and 3, if the exclusive or result 1 (valid) is considered to be that the incoming line cabinet PT sampling voltage is directly used for control, a voltage opposite to the incoming line cabinet in phase is output, and a signal of the T-seat incoming line switch cabinet voltage sampling PT needs to be inverted to be used as a signal for actual control. If the exclusive or result is 0 (invalid), the signal of the T-seat incoming switch cabinet voltage sample PT can be directly used for control.
If no fault occurs, judging whether the FLAG1 (FLAG 1) and the FLAG2 (FLAG 2) are not valid or not, namely performing exclusive or operation, and defining the operation result as FLAG3:
if FLAG3 is 0, there is no problem in using the voltage sampling signal of the switch cabinet PT as control; if FLAG3 is 1, PT voltage acquisition signal u of incoming line switch cabinet is needed T Multiplied by (-1) and then used as a signal for control.
In summary, the invention provides an in-phase power supply serial side voltage sampling polarity automatic correction method. According to the method, the in-phase power supply device is operated to precharge and output an open-loop voltage flow, the polarity of the PT voltage sampling signal of the incoming line switch cabinet is automatically corrected according to the PT voltage sampling signals of the starting cabinet and the incoming line switch cabinet, and the voltage after the polarity is used in control, so that the voltage polarity output by the in-phase power supply device at the serial side is ensured to be matched with the voltage (T seat voltage) of the incoming line switch cabinet, and the overcurrent problem caused by the opposite output voltage of the converter and the incoming line voltage is avoided. The invention provides a sampling direction judging method in a precharge stage and an output open-loop voltage flow in the serial side voltage sampling polarity automatic correction process. During the precharge period of the in-phase power supply device, as the sampled primary voltages are equal in size, the effective values of the starting cabinet and the incoming line switch cabinet PT can be obtained by making differences between the sampled voltage instantaneous values, and whether the sampling directions of the two positions are consistent is judged according to the sizes of the effective values. The method is simple and effective. If the effective value of the difference value is very small, the two sampling directions are consistent; if the effective value of the difference is about 2 times of the rated value, the sampling directions of the two positions are considered to be opposite; if the effective value of the difference is not satisfied in the two cases, sampling or other faults are considered to occur, and a shutdown searching problem is needed. And during the period of outputting the open-loop voltage, judging the voltage sampling direction according to the phase-locked phase angle difference between the open-loop voltage of the starting cabinet and the voltage of the incoming line switch cabinet. This approach is applicable to situations where the voltage magnitudes at two points in the output open loop voltage flow are not consistent. If the angle difference is near 0 degrees, the directions of the two voltage signals are consistent; if the angle difference is about 180 degrees, the directions of the voltage signals at the two positions are opposite; if the angle difference is not satisfied in the two cases, sampling or other faults are considered to occur, and a shutdown searching problem is needed.
It is to be understood that the above-described embodiments of the present invention are merely illustrative of or explanation of the principles of the present invention and are in no way limiting of the invention. Accordingly, any modification, equivalent replacement, improvement, etc. made without departing from the spirit and scope of the present invention should be included in the scope of the present invention. Furthermore, the appended claims are intended to cover all such changes and modifications that fall within the scope and boundary of the appended claims, or equivalents of such scope and boundary.

Claims (7)

1. The method for automatically correcting the sampling polarity of the in-phase power supply serial side voltage is characterized by comprising the following steps of:
the in-phase power supply device is precharged by the incoming line of a circuit breaker at the serial side of the incoming line switch cabinet and a starting circuit of the starting cabinet; during the precharge period, collecting and judging a voltage sampling signal of the T-seat incoming line switch cabinet PT and a voltage signal of the starting cabinet PT, and recording a first FLAG FLAG1 as invalid if the two voltage sampling directions are the same, otherwise, judging as valid;
after the precharge is finished, disconnecting a circuit breaker at the serial side in the T-seat incoming line switch cabinet, generating open-loop modulation waves according to the phase angle of PT voltage of the T-seat incoming line switch cabinet, and outputting open-loop voltage at the serial side;
comparing whether the phase of open-loop voltage of the starting cabinet PT is the same as the direction of a PT signal of the T-seat incoming line switch cabinet, if so, recording that the second FLAG FLAG2 is invalid, otherwise, the second FLAG FLAG2 is valid;
if one of the first FLAG1 and the second FLAG2 is valid and the other is invalid, the voltage signal of the PT sampled by the T-seat incoming line switch cabinet is required to be inverted and used as a signal for actual control, otherwise, the voltage sampling polarity is not required to be corrected;
during precharge, collect T seat inlet wire cubical switchboard PT's voltage sampling signal and start up cabinet interior PT's voltage signal and judge, include: defining the per unit value of the PT sampling instantaneous voltage of the T-seat incoming line switch cabinet as u T The PT sampling instantaneous voltage per unit value of the starting cabinet is u Q Calculating the instantaneous difference delta u=u of two voltage samples T -u Q If the effective value DeltaU of Deltau RMS If the voltage is smaller than 0.3pu, the voltage sampling directions are considered to be the same, and the first FLAG FLAG1 is recorded as invalid; if the effective value DeltaU of Deltau RMS If the voltage is greater than 1.6pu, the voltage sampling directions are considered to be different, and a first FLAG FLAG1 is recorded as effective; if the effective value DeltaU of Deltau RMS Between 0.3pu and 1.6pu, the fault is shut down.
2. The method for automatically correcting the sampling polarity of the in-phase power supply serial side voltage according to claim 1, wherein the in-phase power supply device comprises a power cabinet, a starting cabinet, a T-seat incoming line switch cabinet, a traction matching transformer and an outgoing line switch cabinet;
the power cabinet comprises a plurality of power units for power conversion, the serial side H bridge of each power unit is connected with the starting cabinet after being connected in series, and the parallel side of each power unit is connected with the outgoing switch cabinet through a traction matching transformer respectively;
the outgoing line switch cabinet is connected with the power grid transformer M seat;
the starting cabinet comprises a soft start contactor KM1, a soft start resistor and a main contactor KM2, wherein the soft start resistor and the soft start contactor KM1 are connected in series and then connected in parallel with the main contactor;
the starting cabinet is connected with the T-seat incoming line switch cabinet, and the T-seat incoming line switch cabinet is connected with the T-seat of the power grid transformer.
3. The method for automatically correcting the sampling polarity of the in-phase power supply serial side voltage according to claim 2, wherein the pre-charging process comprises the steps of closing a soft start contactor KM1 of a starting loop in a starting cabinet, closing a breaker QF in a T-base incoming line switch cabinet, closing a main contactor KM2 of the starting loop when the direct current bus capacitor of the power unit is charged to a set value, and opening the soft start contactor KM1.
4. The method for automatically correcting the sampling polarity of the in-phase power supply serial side voltage according to claim 1, wherein after the precharge is completed and the T-seat wire-incoming switch cabinet circuit breaker QF is opened, an open-loop modulation wave is generated according to the phase angle of the T-seat wire-incoming switch cabinet PT voltage, and the serial side outputs the open-loop voltage, comprising:
PT voltage sampling u of T-seat incoming line switch cabinet T Phase locking is carried out, and the phase angle omega of the voltage of the T-seat incoming line switch cabinet obtained by phase locking T t, u mod ＝U open sin(ω T t) is given as an open loop modulated wave, where U open And for the set open-loop modulation degree, the direct-current voltage pre-charged by the direct-current bus capacitor is used for open-loop pulse transmission, and the voltage is output at the serial side port and the starting cabinet.
5. The method for automatically correcting the polarity of in-phase supply series side voltage samples according to claim 4, wherein comparing whether the phase of the open loop voltage sampled by the start-up cabinet PT is the same as the direction of the T-seat incoming line switch cabinet PT voltage signal, comprises:
the voltage sampled by the starting cabinet PT during the current open loop pulse sending is u Q_open For u Q_open Phase locking is carried out to obtain phase angle omega Qo t；
Phase angle omega of T-seat voltage obtained by phase locking T t and phase angle omega Qo t is differenced and takes the absolute value: Δθ= |ω T t-ω Qo I (I); if Δθ is greater than pi, the process yields θ in the range of 0 to pi FLAG2 The method comprises the steps of carrying out a first treatment on the surface of the If theta is FLAG2 Less thanJudging that the open-loop voltage of the starting cabinet is in phase with the voltage of the T seat, and setting a second FLAG FLAG2 as invalid; if the difference value is, θ FLAG2 Is greater than->Judging that the open-loop voltage of the starting cabinet is opposite to the T seat voltage, and setting a second FLAG FLAG2 to be effective; if theta is FLAG2 Between->And->And (5) stopping the machine when the machine fails.
6. The method according to claim 5, wherein if no fault occurs, 0 indicates invalid, 1 indicates valid, and exclusive-or operation is performed on the first FLAG1 and the second FLAG2, and the operation result is defined as FLAG3:
if FLAG3 is 0, the voltage sampling polarity does not need to be corrected; if FLAG3 is 1, the PT voltage acquisition signal u of the T-seat incoming line switch cabinet is required T Multiplied by-1) And then used as a signal for control.
7. The method for automatic correction of in-phase supply series side voltage sampling polarity according to claim 5, wherein if Δθ is greater than pi, the processing obtains θ in a range of 0 to pi FLAG2 Comprising: if the angle is greater than pi, θ FLAG2 ＝2π-|Δθ|。
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