CN110932266A - Power grid signal identification method of star-connected high-voltage high-power electric energy quality control device - Google Patents
Power grid signal identification method of star-connected high-voltage high-power electric energy quality control device Download PDFInfo
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Abstract
The invention provides a power grid signal identification method of a star-connection high-voltage high-power electric energy quality control device, which finally judges the phase sequence relation of a device access three-phase power grid, the corresponding relation of a power grid voltage PT sampling signal and a power grid primary system and the corresponding relation of a power grid current CT sampling signal and the power grid primary system by acquiring a power grid voltage signal, a power grid current signal and an input current signal of a device body of the star-connection high-voltage high-power electric energy quality control device and carrying out operation analysis on different signal combinations, finally realizes the intelligent identification of the power grid signal of the star-connection high-voltage high-power electric energy quality control device, simplifies the complexity of equipment installation and line calibration, and can effectively improve the safety and reliability of equipment.
Description
Technical Field
The invention relates to the technical field of power electronics, in particular to a power grid signal identification method of a star-connected high-voltage high-power quality control device.
Background
With the continuous development of social economy and the continuous improvement of the scientific and technical level, the types and power levels of electric loads of an electric power system are also continuously increased, and particularly, the wide use of high-power electronic devices leads to more and more prominent problems of electric power quality such as serious low power factor of the electric power system, unbalanced load of a power grid, harmonic pollution of the electric power system, even unbalanced voltage of the electric power system and the like, and seriously harms the stability of the electric power system and the safety of user equipment.
In order to solve the problem of power quality of a power system, the star-connected high-voltage high-power quality control device based on the power electronic power device is more and more widely applied except the traditional compensation devices such as a fixed capacitor, a switch switching capacitor and the like. The high-power electric energy quality management device based on the power electronic power device can quickly compensate reactive power, harmonic waves, unbalanced load and unbalanced voltage of a power grid, has the advantages of higher response speed and compensation rate, can dynamically adjust compensation frequency according to harmonic characteristics of the power grid, cannot generate impact on the power grid in the compensation process and the like.
The star-connection high-voltage high-power electric energy quality control device based on the power electronic power device has excellent compensation performance, but the star-connection high-voltage high-power electric energy quality control device needs to be accurately connected to a primary system of a power grid in normal operation, provides accurate grid voltage PT signals, grid current CT signals and the like, and when the primary wiring of the grid voltage, grid voltage PT sampling signals or grid current CT sampling signals is in wrong wiring, the compensation effect of the star-connection high-voltage high-power electric energy quality control device based on the power electronic power device can be obviously reduced, and the control device can not operate or even be damaged in serious conditions. Therefore, strict manual verification of the electrical wiring is required in the use process, and the safety of equipment can be seriously damaged once the manual wiring calibration is wrong. Therefore, the intelligent identification algorithm of the power grid signal of the star-connection high-voltage high-power quality control device based on the power electronic power device needs to be researched so as to reduce the complexity of installation and operation of the star-connection high-voltage high-power quality control device and obviously improve the safety and reliability of equipment operation.
Disclosure of Invention
In order to solve the problems of the background art, the invention provides a power grid signal identification method of a star-connected high-voltage high-power quality control device, the algorithm finally judges the phase sequence relation of a three-phase power grid accessed by the device, the corresponding relation of a power grid voltage PT sampling signal and a power grid primary system and the corresponding relation of a power grid current CT sampling signal and the power grid primary system through acquiring a power grid voltage signal, a power grid current signal and an input current signal of a device body and carrying out operation analysis on different signal combinations, and finally realizes the intelligent identification of the power grid signal of the star-connected high-voltage high-power quality control device, simplifies the complexity of equipment installation and line calibration, and can effectively improve the safety and reliability of equipment in operation.
In order to achieve the purpose, the invention adopts the following technical scheme:
a power grid signal identification method of a star-connected high-voltage high-power electric energy quality management device comprises the following steps:
firstly, sampling and operating three-phase input current signals of the device to confirm the phase sequence of a primary system of the device accessed to a power grid;
secondly, determining the phase sequence and phase relation of the three-phase PT sampling signals of the grid voltage by combining the three-phase input current sampling signals of the device according to the phase sequence result of the three-phase input primary voltage;
after the primary phase sequence relation of the grid voltage and the phase sequence and phase relation of the grid voltage three-phase PT sampling signal are determined, the star-connected high-voltage high-power electric energy quality control device can be started to operate, but the compensation effect is possibly incorrect;
and fourthly, starting the star-connection high-voltage high-power electric energy quality control device and outputting a small current step, detecting a three-phase power grid current CT signal and calculating to finally determine the phase sequence and phase relation of the power grid current CT sampling signal, and realizing intelligent identification of the power grid signal of the star-connection high-voltage high-power electric energy quality control device.
Further, the first step specifically includes the following steps:
101, when the power quality control device operates, three-phase primary electrical connection with a power grid is required, and a three-phase PT sampling signal U of the voltage of the power grid is required to be acquireda、UbAnd UcThree-phase CT sampling signal I of power grid currentga、IgbAnd Igc(ii) a Input current detection device and secondary sampling signal I thereof when electric energy quality control device operatesca、IcbAnd IccAll the signals are wiring signals inside the equipment, and the signals can be easily checked and confirmed during field installation and debugging;
102, before starting and running, the star-connected high-voltage high-power electric energy quality control device firstly charges a unit direct-current side capacitor through a charging resistor and a unit diode uncontrolled rectifier circuit, when the voltage of two ends of the unit direct-current capacitor reaches a certain threshold value, a bypass contactor automatically closes, and after the bypass contactor closes, the star-connected high-voltage high-power electric energy quality control device inputs current I in a short timeca、IcbAnd IccAll will have short-time impact, and the input current of the device is controlled by the quality of the electric energyThe detection device and the feedback signal wiring thereof are all internal elements or wiring of the equipment, the signal can be considered to be accurate and reliable after field installation, debugging and confirmation, and the three-phase input current signal I of the device can be treated by the power qualityca、IcbAnd IccIntelligently identifying an external input signal of the power quality control device as a reference;
step 103, utilizing the input current I of the equipment in the pre-charging process of the deviceca、IcbAnd IccThe impact direction carries out intelligent identification and judgment on the three-phase input voltage primary wiring phase sequence of the star-connection high-voltage high-power electric energy quality control device:
1) when the three-phase primary voltage of the power grid is normally connected to the star-connection high-voltage high-power electric energy quality control device, the system can be equivalent to a three-phase diode uncontrolled rectifying circuit after the bypass contactor is switched on, and at the moment, according to the three-phase primary actual voltage of the power grid, the instantaneous maximum absolute value of the power grid voltage and the three-phase input current waveform of the star-connection high-voltage high-power electric energy quality control device: the sequence of the maximum absolute value of the power grid voltage is + Uab，-Uca，+Ubc，-Uab，+Uca，-UbcWhen the grid voltage is connected in a positive sequence, the three-phase voltage can be divided into the 6 sections in one period and sequentially and circularly appear according to the sequence, and the current waveform of the star-connected high-voltage high-power electric energy quality control device is as follows: if the instantaneous value of the defined current is 1 when being larger than zero, 2 when being smaller than zero and 0 when being equal to zero, the three-phase input current direction combination I of the star-connected high-voltage high-power electric energy quality control deviceaIbIcThe corresponding relations in the six time intervals are sequentially (120, 102, 012, 210, 201, 021), and the table forms are shown in the following table 1;
table 1: three-phase input current direction combination and primary voltage peak value corresponding relation of star-connected high-voltage high-power electric energy quality control device
| Location of voltage peak | +Uab | -Uca | +Ubc | -Uab | +Uca | -Ubc |
| Current direction combination | 120 | 102 | 012 | 210 | 201 | 021 |
2) The star connects high-power electric energy quality of high pressure to administer the device and finishes precharging and the bypass contactor closes the back short time device three-phase input current impact obviously, because the bypass contactor closes the back short time device three-phase input current impact obviously easily judges, so can judge the device three-phase input current direction combination in this period: if the current impact in 3 sections is obvious after the bypass contactor is switched on, and the three-phase input current direction combination is (021, 120 and 102) in sequence, the result of the three-phase input current direction combination shows that the grid voltage is in positive phase sequence connection and the maximum absolute value of the grid voltage is-U in sequencebc，+Uab，-Uca；
3) Judging according to the input current impact waveform of the star-connected high-voltage high-power electric energy quality control device in a short time after the bypass contactor is switched on: if the three-phase input current direction combination is (012, 102, 120) in sequence, the grid voltage is connected in a negative phase sequence; at the moment, the control system can prompt that the error of the primary wiring phase sequence requires a constructor to adjust primary wiring or adjust the phase sequence of the B phase and the C phase in the control system; if the B-phase and C-phase sampling and control signals are exchanged and adjusted in the control system, the three-phase input current direction combination shifts (021, 120 and 102) after the adjustment is finished, and the system restores to positive phase sequence wiring.
Further, the second step specifically includes the following steps:
after the primary wiring of the three-phase input voltage is intelligently identified, the input current I of the equipment in the pre-charging process of the device needs to be reusedca、IcbAnd IccThe impulse current direction carries out intelligent identification and judgment to the three-phase voltage PT sampling signal wiring of the star-connection high-voltage high-power electric energy quality control device:
according to the combined result of the input current directions of the star-connection high-voltage high-power quality control device when the corrected grid voltage is subjected to one-time positive phase sequence wiring, the instantaneous maximum value sequence relation of the grid voltage can be confirmed, and intelligent identification and judgment can be performed on grid voltage three-phase PT sampling signals by comparing the grid voltage PT signal sampling results;
1) if the star-connected high-voltage high-power electric energy quality control device accords with the three-phase input current and the three-phase power grid voltage sampling PT signal in a short time after the bypass contactor is switched on: the three-phase input current direction combination of the star-connected high-voltage high-power electric energy quality control device is (021, 120 and 102) in sequence, and the occurrence sequence of the instantaneous maximum values of the power grid voltage is-U in sequencebc，+Uab，-Uca；
The maximum values of the grid voltage PT sampling signals corresponding to the three-phase input current impact waveforms sequentially appear in an order of-U23，+U12，-U31(ii) a Is composed of-Ubc＝-U23Equation U can be derivedb-Uc＝U2-U3And is composed of + Uab＝+U12Then equation U can be obtaineda-Ub＝U1-U2Then is made of-Uca＝-U31Can obtain Uc-Ua＝U3-U1Simultaneous three equations to obtain a system of equations
The three-phase grid voltage also satisfies the relation of three-phase voltage sum being zero without considering the influence of zero sequence voltage, i.e. the three-phase grid voltage
The correct phase corresponding relation of the PT sampling signals of the three-phase power grid voltage can be obtained by simultaneously solving the two equation sets
According to the intelligent recognition result, the power grid voltage PT signal is accurately wired, and the PT signal is correctly corresponding to the actual three-phase voltage one-time wiring;
2) if the star-connected high-voltage high-power electric energy quality control device accords with the three-phase input current and the three-phase power grid voltage sampling PT signal in a short time after the bypass contactor is switched on: the three-phase input current direction combinations of the star-connected high-voltage high-power electric energy quality control device are respectively (021, 120 and 102), and the occurrence sequence of the instantaneous maximum values of the network voltage is-Ubc，+Uab，-Uca；
The maximum value of the grid voltage PT sampling signals corresponding to the three-phase input current impact waveform sequentially appears in a sequence of + U12，-U31，+U23(ii) a Then is composed of-Ubc＝+U12Equation U can be derivedb-Uc＝-U1+U2And is composed of + Uab＝-U31Then equation U can be obtaineda-Ub＝U1-U3Then is made of-Uca＝+U23Can obtain Ua-Uc＝U2-U3Simultaneous three equations to obtain a system of equations
The three-phase grid voltage also satisfies the relation of three-phase voltage sum being zero without considering the influence of zero sequence voltage, i.e. the three-phase grid voltage
The correct phase corresponding relation of the PT sampling signals of the three-phase power grid voltage can be obtained by simultaneously solving the two equation sets
According to the intelligent recognition result, the power grid voltage PT signal homonymous terminal connection error can be known, and meanwhile, the corresponding relation between the three-phase PT signal and the power grid voltage primary connection is abnormal; the star-connected high-voltage high-power electric energy quality control device control system can give prompt information according to the intelligent identification result of the grid voltage PT sampling signals to require constructors to adjust the PT signal wiring, and can also automatically adjust the grid voltage PT sampling signals in the control system to restore the corresponding relation between the grid voltage PT sampling signals and the grid voltage primary wiring.
Further, the fourth step specifically includes the following steps:
according to the electrical connection principle of the star connection high-voltage high-power quality control device, the following relations exist between the power grid current and the load current and between the star connection high-voltage high-power quality control device input current:
the star-connected high-voltage high-power quality control device can be started and input current of the star-connected high-voltage high-power quality control device changes in step by utilizing the current relation formula, and the following relation between the power grid current and the input current of the star-connected high-voltage high-power quality control device can be obtained because the load current is not obviously changed in a short time of the input current step of the star-connected high-voltage high-power quality control device;
by utilizing the formula, when the input current of the star-connected high-voltage high-power electric energy quality treatment device changes in step, the corresponding relation between the grid current CT sampling signal and the input current phase of the star-connected high-voltage high-power electric energy quality treatment device can be easily identified by respectively calculating the change of the input current and the grid current of the star-connected high-voltage high-power electric energy quality treatment device, so that the intelligent identification of the grid current CT sampling signal is realized, and the wiring prompt of the grid current CT sampling signal can be provided to field constructors according to the intelligent identification algorithm result or the automatic adjustment operation of the grid current CT sampling signal can be carried out in a control system of the star-connected high-voltage high-power electric energy.
Compared with the prior art, the invention has the beneficial effects that:
according to the method, after the bypass contactor is switched on in the pre-charging process of the star-connected high-voltage high-power electric energy quality treatment device, the three-phase input current waveform and the grid voltage three-phase PT sampling signal waveform of the star-connected high-voltage high-power electric energy quality treatment device in a short time can be used for intelligently identifying and automatically correcting the corresponding relation of the three-phase primary wiring phase sequence of the grid voltage and the three-phase PT sampling signal phase of the grid voltage. And after the star-connected high-voltage high-power electric energy quality control device is started and operated, the device inputs current step change instant power grid current three-phase CT sampling signal step change data, so that intelligent identification and automatic correction of the power grid current three-phase CT sampling signal can be realized. According to the algorithm, additional detection equipment and cost are not required to be added, intelligent identification of external input signals of the star-connection high-voltage high-power electric energy quality control device can be achieved only through the internal control algorithm of the control system, complex power failure line calibration operation on site is reduced, workload and accident risk during line calibration debugging in site construction are effectively reduced, and meanwhile safety and reliability of operation of the device can be effectively improved.
1) Without increasing the system cost of the device
According to the method, the three-phase input current waveform and the grid voltage three-phase PT sampling signal waveform of the star-connected high-voltage high-power quality control device in a short time after the bypass contactor is switched on in the pre-charging process of the star-connected high-voltage high-power quality control device are collected, so that the intelligent identification and automatic correction of the corresponding relation of the three-phase primary wiring phase sequence of the grid voltage and the three-phase PT sampling signal phase of the grid voltage can be realized. After the star-connected high-voltage high-power electric energy quality control device is started and operated, the device inputs the instantaneous power grid current three-phase CT sampling signal step change data of the current step change, and intelligent identification and automatic correction of the power grid current three-phase CT sampling signal can be realized. All control algorithms are completed by control system software of the star-connected high-voltage high-power electric energy quality control device, and the required external input signals are signals necessary for normal operation of the star-connected high-voltage high-power electric energy quality control device, so that no hardware facilities are required to be added, and the system cost of the device is not increased;
2) can reduce the workload of the field installation and debugging process
A power grid signal intelligent identification method of a star-connected high-voltage high-power quality control device realizes intelligent identification and correction of power grid signals through a device control system software algorithm, effectively avoids complicated on-site line calibration operation, can greatly reduce the workload in the on-site installation and debugging process, improves the working speed and the working quality of on-site installation and debugging, and saves the equipment installation and debugging cost;
3) can reduce the accident risk caused by field power failure, power transmission and line calibration operation
For a star-connected high-voltage high-power electric energy quality control device, if a wiring error is found during field debugging, particularly when a three-phase PT signal or a three-phase CT signal of a grid voltage is in error, a high-voltage power supply loop of the whole area needs to be disconnected, the wiring of the three-phase PT signal or the CT signal is re-calibrated under the condition that a PT or CT detection device is not electrified, and the PT or CT signal possibly passes through a plurality of sets of other devices, so that the workload of the wiring calibration is large, the operation is complicated, and the correctness of the wiring calibration result can be judged again only by re-powering after the wiring calibration is finished. The intelligent identification algorithm of the power grid signal of a kind of star-connected high-pressure high-power electric energy quality governance device, realize the intellectual identification and automatic correction to the power grid signal through the software algorithm of the control system of the device, can avoid the work of revising the line and adjusting the wiring when the on-the-spot wiring is wrong, reduce the accident risk caused by regional power failure and power transmission operation and on-the-spot wiring operation, also greatly reduce the regional power failure to other electric power equipments and peripheral electric power users' influence, greatly reduce the accident risk;
4) can ensure the safe and reliable operation of the equipment
The intelligent identification method for the power grid signal of the star-connection high-voltage high-power quality control device realizes intelligent identification and automatic correction of the power grid signal through a device control system software algorithm, avoids the risks of equipment starting failure, non-ideal equipment compensation effect, even equipment damage and the like caused by external input signal wiring errors, and effectively ensures the safe and reliable performance of equipment operation.
Drawings
FIG. 1 is an electrical connection schematic diagram of a star-connected high-voltage high-power quality control device;
FIG. 2 is an equivalent circuit diagram of a primary system of a star-connected high-voltage high-power quality control device;
FIG. 3 is a typical waveform of a diode uncontrolled rectifying circuit when a star-connected high-voltage high-power quality control device is charged;
FIG. 4 is a system waveform when a bypass contactor is switched on when a star-connected high-voltage high-power electric energy quality control device is connected in a positive sequence at one time;
FIG. 5 is a system waveform when a bypass contactor is switched on when a primary negative sequence wiring of a star-connected high-voltage high-power electric energy quality control device is performed;
FIG. 6 is a closing waveform of a bypass contactor when PT signals of a star-connected high-voltage high-power quality control device are normally connected;
fig. 7 is a closing waveform of the bypass contactor when a PT signal of the star-connected high-voltage high-power electric energy quality control device is abnormally connected.
Detailed Description
The following detailed description of the present invention will be made with reference to the accompanying drawings.
A power grid signal identification method of a star-connected high-voltage high-power electric energy quality management device comprises the following steps:
firstly, sampling and operating three-phase input current signals of the device to confirm the phase sequence of a primary system of the device accessed to a power grid;
secondly, determining the phase sequence and phase relation of the three-phase PT sampling signals of the grid voltage by combining the three-phase input current sampling signals of the device according to the phase sequence result of the three-phase input primary voltage;
after the primary phase sequence relation of the grid voltage and the phase sequence and phase relation of the grid voltage three-phase PT sampling signal are determined, the star-connected high-voltage high-power electric energy quality control device can be started to operate, but the compensation effect is possibly incorrect;
and fourthly, starting the star-connection high-voltage high-power electric energy quality control device and outputting a small current step, detecting a three-phase power grid current CT signal and calculating to finally determine the phase sequence and phase relation of the power grid current CT sampling signal, and realizing intelligent identification of the power grid signal of the star-connection high-voltage high-power electric energy quality control device.
The first step specifically comprises the following steps:
the electrical connection principle of the star-connection high-voltage high-power quality control device is shown in figure 1, the power quality control device needs to be electrically connected with a power grid in three phases once when in operation, and simultaneously needs to acquire a power grid voltage three-phase PT sampling signal Ua、UbAnd UcThree-phase CT sampling signal I of power grid currentga、IgbAnd Igc. Input current detection device and secondary sampling signal I thereof when electric energy quality control device operatesca、IcbAnd IccAll are equipment internal wiring signals, and the signals can be easily checked and confirmed during field installation and debugging.
The equivalent circuit of the primary system of the star-connected high-voltage high-power electric energy quality control device is shown in figure 2, and the star-connected high-voltage high-power electric energy quality control device is charged before starting operationThe resistor and the unit diode uncontrolled rectifier circuit charge the unit direct current side capacitor, the bypass contactor automatically closes after the voltage of two ends of the unit direct current capacitor reaches a certain threshold value, and the input current I of the high-voltage high-power electric energy quality control device is star-connected in a short time after the bypass contactor closesca、IcbAnd IccShort-time impact can occur, and because the input current detection device of the power quality control device and the feedback signal wiring thereof are all internal elements or wiring of the equipment, the signal can be considered to be accurate and reliable after being installed, debugged and confirmed on site, and the three-phase input current signal I of the power quality control device can be usedca、IcbAnd IccAnd intelligently identifying the external input signal of the power quality control device for the reference.
The intelligent power grid signal identifying method for star-connected high-voltage high-power quality control device includes the first step of utilizing the input current I of the equipment in the pre-charging processca、IcbAnd IccThe impact direction of the intelligent identification and judgment device is used for intelligently identifying and judging the primary wiring phase sequence of the three-phase input voltage of the star-connection high-voltage high-power electric energy quality control device. When the three-phase primary voltage of the power grid is normally connected to the star connection high-voltage high-power electric energy quality control device, the system can be equivalent to a three-phase diode uncontrolled rectifying circuit after the bypass contactor is switched on, and the three-phase primary actual voltage of the power grid, the instantaneous maximum absolute value of the power grid voltage and the three-phase input current waveform of the star connection high-voltage high-power electric energy quality control device are shown in figure 3. The sequence of the maximum absolute value of the grid voltage is + Uab，-Uca，+Ubc，-Uab，+Uca，-UbcWhen the grid voltages are connected in a positive sequence, the three-phase voltages can be divided into the above 6 sections in one period and sequentially appear in a circulating manner according to the sequence, and the current waveforms of the star-connected high-voltage high-power electric energy quality control device are shown in fig. 3. If the instantaneous value of the defined current is 1 when being larger than zero, 2 when being smaller than zero and 0 when being equal to zero, the three-phase input current direction combination I of the star-connected high-voltage high-power electric energy quality control deviceaIbIcThe corresponding relations in the six time intervals are (120, 102, 012, 210, 201, 021) in sequence, and the corresponding relations are arranged into a table typeThe formula is shown in table 1 below.
Table 1: three-phase input current direction combination and primary voltage peak value corresponding relation of star-connected high-voltage high-power electric energy quality control device
| Location of voltage peak | +Uab | -Uca | +Ubc | -Uab | +Uca | -Ubc |
| Current direction combination | 120 | 102 | 012 | 210 | 201 | 021 |
The star-connected high-voltage high-power electric energy quality control device is obviously impacted by three-phase input current in a short time after the pre-charging is finished and the bypass contactor is switched on, and the waveform of the star-connected high-voltage high-power electric energy quality control device is shown in figure 4. Since the three-phase input current impact of the device is obviously easy to judge in a short time after the bypass contactor is switched on, the three-phase input current impact of the device can be judged in the time periodJudging the combination, as can be seen from fig. 4, the current impact in 3 sections is obvious after the bypass contactor is switched on, the three-phase input current direction combination is (021, 120, 102) in sequence, and as can be seen from the three-phase input current direction combination result, the grid voltage is in positive phase sequence connection, and the maximum absolute value of the grid voltage is-U in sequencebc，+Uab，-Uca。
If the input current impulse waveform of the star-connected high-voltage high-power electric energy quality control device in a short time after the bypass contactor is switched on is shown in fig. 5, the three-phase input current direction combination is (012, 102, 120) in sequence, and the grid voltage is connected in a negative phase sequence. At the moment, the control system can prompt that the error of the primary wiring phase sequence requires a constructor to adjust primary wiring or adjust the phase sequence of the B phase and the C phase in the control system. If the B-phase and C-phase sampling and control signals are exchanged and adjusted in the control system, the three-phase input current direction combination shifts (021, 120 and 102) after the adjustment is finished, and the system restores to positive phase sequence wiring.
Step two, the step two specifically includes the following:
a method for intelligently recognizing the electric network signal of star-connected high-voltage high-power electric energy quality controller features that after the primary connection of three-phase input voltage is intelligently recognized, the input current I of equipment in the pre-charging procedure of said device is used againca、IcbAnd IccThe impulse current direction carries out intelligent identification and judgment on the three-phase voltage PT sampling signal wiring of the star-connection high-voltage high-power electric energy quality control device. According to the combined result of the input current directions of the star-connection high-voltage high-power electric energy quality control device during the primary positive phase sequence wiring of the corrected grid voltage, the instantaneous maximum value sequence relation of the grid voltage can be confirmed, and intelligent identification and judgment can be performed on grid voltage three-phase PT sampling signals by comparing the grid voltage PT signal sampling results.
If the three-phase input current and the three-phase power grid voltage sampling PT signal of the star-connected high-voltage high-power quality control device in a short time after the bypass contactor is switched on are as shown in fig. 6, it can be seen from the figure that the three-phase input current direction combinations of the star-connected high-voltage high-power quality control device are (021, 120, 102) in sequence, and the instantaneous maximum value of the power grid voltage appears to be along withThe sequence should be-U in sequencebc，+Uab，-Uca. And as can be seen from fig. 6, the occurrence sequence of the maximum values of the grid voltage PT sampling signals corresponding to the three-phase input current impact waveforms is-U in sequence23，+U12，-U31. Is composed of-Ubc＝-U23Equation U can be derivedb-Uc＝U2-U3And is composed of + Uab＝+U12Then equation U can be obtaineda-Ub＝U1-U2Then is made of-Uca＝-U31Can obtain Uc-Ua＝U3-U1Simultaneous three equations to obtain a system of equations
The three-phase grid voltage also satisfies the relation of three-phase voltage sum being zero without considering the influence of zero sequence voltage, i.e. the three-phase grid voltage
The correct phase corresponding relation of the PT sampling signals of the three-phase power grid voltage can be obtained by simultaneously solving the two equation sets
According to the intelligent recognition result, the power grid voltage PT signal is accurately wired, and the PT signal is correctly corresponding to the actual three-phase voltage one-time wiring.
If the three-phase input current and the three-phase grid voltage sampling PT signal of the star-connected high-voltage high-power quality control device in a short time after the bypass contactor is switched on are shown in fig. 7, it can be seen from the figure that the three-phase input current direction combinations of the star-connected high-voltage high-power quality control device are respectively (021, 120, 102), and the occurrence sequence of the instantaneous maximum values of the grid voltage is-Ubc，+Uab，-Uca. In contrast, as shown in fig. 7, the occurrence sequence of the maximum values of the power grid voltage PT sampling signals corresponding to the three-phase input current impulse waveforms is + U12，-U31，+U23. Then is composed of-Ubc＝+U12Equation U can be derivedb-Uc＝-U1+U2And is composed of + Uab＝-U31Then equation U can be obtaineda-Ub＝U1-U3Then is made of-Uca＝+U23Can obtain Ua-Uc＝U2-U3Simultaneous three equations to obtain a system of equations
The three-phase grid voltage also satisfies the relation of three-phase voltage sum being zero without considering the influence of zero sequence voltage, i.e. the three-phase grid voltage
The correct phase corresponding relation of the PT sampling signals of the three-phase power grid voltage can be obtained by simultaneously solving the two equation sets
According to the intelligent recognition result, the power grid voltage PT signal homonymous terminal connection error can be known, and meanwhile, the corresponding relation between the three-phase PT signal and the power grid voltage primary connection is abnormal. The star-connected high-voltage high-power electric energy quality control device control system can give prompt information according to the intelligent identification result of the grid voltage PT sampling signals to require constructors to adjust the PT signal wiring, and can also automatically adjust the grid voltage PT sampling signals in the control system to restore the corresponding relation between the grid voltage PT sampling signals and the grid voltage primary wiring.
Step three, the step three specifically includes the following:
the star-connected high-voltage high-power electric energy quality control device can normally start to operate after completing intelligent identification and correction of a grid voltage primary wiring phase sequence and a grid voltage PT sampling signal, but because intelligent identification and correction are not carried out on a grid current CT sampling signal, compensation effect on the grid electric energy quality problem after the star-connected high-voltage high-power electric energy quality control device operates may be unsatisfactory and even error compensation exists, and therefore intelligent identification and correction need to be carried out on a grid current CT sampling signal wiring.
Fourthly, the fourth step specifically comprises the following steps:
the star-connected high-voltage high-power electric energy quality control device shown in figure 1According to the gas connection schematic diagram, the following relationship exists between the power grid current and the load current and the input current of the star-connected high-voltage high-power quality control device
The star-connected high-voltage high-power quality control device can be started and input current of the star-connected high-voltage high-power quality control device is changed in step by utilizing the current relation formula, and the following relation exists between the power grid current and the input current of the star-connected high-voltage high-power quality control device because the load current can be considered to be not obviously changed in a short time of the input current step of the star-connected high-voltage high-power quality control device
By utilizing the formula, when the input current of the star-connected high-voltage high-power electric energy quality treatment device changes in step, the corresponding relation between the grid current CT sampling signal and the input current phase of the star-connected high-voltage high-power electric energy quality treatment device can be easily identified by respectively calculating the change of the input current and the grid current of the star-connected high-voltage high-power electric energy quality treatment device, so that the intelligent identification of the grid current CT sampling signal is realized, and the wiring prompt of the grid current CT sampling signal can be provided to field constructors according to the intelligent identification algorithm result or the automatic adjustment operation of the grid current CT sampling signal can be carried out in a control system of the star-connected high-voltage high-power electric energy.
Fifthly, the star-connected high-voltage high-power electric energy quality treatment device comprises: the star connection chain type high-voltage reactive power compensation device based on the power electronic power device, the star connection chain type high-voltage active filtering device based on the power electronic power device, the three-level high-voltage reactive power compensation device based on the power electronic power device and the three-level high-voltage active filtering device based on the power electronic power device.
Sixthly, the following is a detailed explanation of the attached drawings:
fig. 1 is an electrical connection schematic diagram of a star-connection high-voltage high-power electric energy quality control device, the device is connected to a three-phase power grid in a parallel connection mode, the device needs to be connected with the three-phase power grid in a positive phase sequence when being input once, and the device can only normally operate when a three-phase PT sampling signal of the voltage of the power grid and a three-phase CT sampling signal of the current of the power grid need to be accurately. The device is internally provided with the three-phase input current detection device, so that the input current of the device can be accurately detected, and the wiring check is convenient.
Fig. 2 is an equivalent circuit diagram of a primary system of a star-connected high-voltage high-power electric energy quality control device, wherein the primary system can be equivalent to a diode uncontrolled rectifier device with a direct-current side support capacitor before a fully-controlled switch device is triggered to operate.
FIG. 3 is a typical waveform of a diode uncontrolled rectification circuit when a star-connected high-voltage high-power electric energy quality control device is charged, and it can be seen from the figure that if a three-phase system is connected in positive phase sequence at one time, the occurrence sequence of the instantaneous peak value of the power grid voltage is always + Uab，-Uca，+Ubc，-Uab，+Uca，-UbcAnd the star connection high-voltage high-power electric energy quality control device always has two phases with input current impact near the voltage peak point of the power grid line, and the two phases of the input current impact are always opposite in direction and basically equal in magnitude. It can be seen from fig. 3 that when the peak value of the grid voltage is + UabTime Ica>0、Icb<0、Icc0; when the peak value of the grid voltage is-UcaTime Ica>0、Icb＝0、Icc<0; when the peak value of the grid voltage is + UbcTime Ica＝0、Icb>0、Icc<0; when the peak value of the grid voltage is-UabTime Ica<0、Icb>0、Icc0; when the peak value of the grid voltage is + UcaTime Ica<0、Icb＝0、Icc>0; when the peak value of the grid voltage is-UbcTime Ica＝0、Icb<0、Icc>0；
FIG. 4 is a system waveform of the bypass contactor when the star-connected high-voltage high-power quality control device is connected in a positive sequence, and it can be seen from the figure that the occurrence sequence of the input current impact of the star-connected high-voltage high-power quality control device is Ica＝0、Icb<0、Icc>0；Ica>0、Icb<0、Icc0 and Ica>0、Icb＝0、Icc<0. The input current impact of the star-connected high-voltage high-power quality control device sequentially appears in the positive direction sequence, so that the fact that the primary wiring of the star-connected high-voltage high-power quality control device is positive phase sequence wiring can be judged, and the primary wiring is correct without adjustment.
FIG. 5 is a system waveform of the bypass contactor when the bypass contactor is switched on when the star-connected high-voltage high-power quality control device is connected with a negative sequence at one time, and it can be seen from the figure that the occurrence sequence of the input current impact of the star-connected high-voltage high-power quality control device is I in sequenceca＝0、Icb>0、Icc<0；Ica>0、Icb＝0、Icc<0 and Ica>0、Icb<0、I cc0. The input current impact of the star-connected high-voltage high-power quality control device sequentially appears in the reverse sequence, so that the fact that the primary wiring of the star-connected high-voltage high-power quality control device is negative phase sequence wiring can be judged, and the wiring needs to be adjusted by an external adjusting or control system automatically to be positive phase sequence.
FIG. 6 is a diagram showing the closing waveforms of the bypass contactor when the PT signal of the star-connected high-voltage high-power quality control device is normally connected, and it can be seen from the diagram that the input current impact sequence of the star-connected high-voltage high-power quality control device is Ica＝0、Icb<0、Icc>0；Ica>0、Icb<0、Icc0 and Ica>0、Icb＝0、Icc<0, so that the actual occurrence sequence of the grid voltage peak values can be judged to be-Ubc，+Uaband-Uca. The voltage peak value appearance sequence of the grid voltage three-phase PT sampling signal is-U23，+U12and-U31Under the condition of not considering the influence of zero sequence voltage, the three-phase power grid voltage should be zero, and the intelligent identification result of the three-phase PT sampling signal of the power grid voltage is U according to the resulta＝U1，Ub＝U2，Uc＝U3And the three-phase PT signal wiring of the grid voltage is correct without adjustment.
FIG. 7 is a star connection highWhen the PT signal of the voltage high-power electric energy quality control device is normally connected, the closing waveform of the bypass contactor is shown, and the input current impact sequence of the star connection high-voltage high-power electric energy quality control device is Ica＝0、Icb<0、Icc>0；Ica>0、Icb<0、Icc0 and Ica>0、Icb＝0、Icc<0, so that the actual occurrence sequence of the grid voltage peak values can be judged to be-Ubc，+Uaband-Uca. The voltage peak value appearance sequence of the grid voltage three-phase PT sampling signals is + U12，-U31，+U23Under the condition of not considering the influence of zero sequence voltage, the three-phase power grid voltage should be zero, and the intelligent identification result of the three-phase PT sampling signal of the power grid voltage is U according to the resulta＝-U3，Ub＝-U1，Uc＝-U2The corresponding relation between the PT signal wiring of the three phases of the grid voltage and the real phase of the three phases of the grid voltage is correct by automatically adjusting the PT sampling signal of the three phases of the grid voltage by an external adjusting PT signal wiring or a star-connected high-voltage high-power electric energy quality control device control system.
The above embodiments are implemented on the premise of the technical solution of the present invention, and detailed embodiments and specific operation procedures are given, but the scope of the present invention is not limited to the above embodiments. The methods used in the above examples are conventional methods unless otherwise specified.
Claims (4)
1. A power grid signal identification method of a star-connected high-voltage high-power electric energy quality control device is characterized by comprising the following steps:
firstly, sampling and operating three-phase input current signals of the device to confirm the phase sequence of a primary system of the device accessed to a power grid;
secondly, determining the phase sequence and phase relation of the three-phase PT sampling signals of the grid voltage by combining the three-phase input current sampling signals of the device according to the phase sequence result of the three-phase input primary voltage;
after determining the primary phase sequence relation of the grid voltage and the phase sequence and phase relation of the grid voltage three-phase PT sampling signal, the star connection high-voltage high-power electric energy quality control device can be started to operate;
and fourthly, starting the star-connection high-voltage high-power electric energy quality control device and outputting a small current step, detecting a three-phase power grid current CT signal and calculating to finally determine the phase sequence and phase relation of the power grid current CT sampling signal, and realizing intelligent identification of the power grid signal of the star-connection high-voltage high-power electric energy quality control device.
2. The power grid signal identification method of the star-connected high-voltage high-power quality control device according to claim 1, wherein the first step specifically comprises the following steps:
101, when the power quality control device operates, three-phase primary electrical connection with a power grid is required, and a three-phase PT sampling signal U of the voltage of the power grid is required to be acquireda、UbAnd UcThree-phase CT sampling signal I of power grid currentga、IgbAnd Igc(ii) a Input current detection device and secondary sampling signal I thereof when electric energy quality control device operatesca、IcbAnd IccAll the signals are wiring signals inside the equipment, and the signals can be easily checked and confirmed during field installation and debugging;
102, before starting and running, the star-connected high-voltage high-power electric energy quality control device firstly charges a unit direct-current side capacitor through a charging resistor and a unit diode uncontrolled rectifier circuit, when the voltage of two ends of the unit direct-current capacitor reaches a certain threshold value, a bypass contactor automatically closes, and after the bypass contactor closes, the star-connected high-voltage high-power electric energy quality control device inputs current I in a short timeca、IcbAnd IccShort-time impact can occur, and because the input current detection device of the power quality control device and the feedback signal wiring thereof are all internal elements or wiring of the equipment, the signal can be considered to be accurate and reliable after being installed, debugged and confirmed on site, and the three-phase input current signal I of the power quality control device can be usedca、IcbAnd IccIntelligently identifying an external input signal of the power quality control device as a reference;
step 103, utilizing the input current I of the equipment in the pre-charging process of the deviceca、IcbAnd IccThe impact direction carries out intelligent identification and judgment on the three-phase input voltage primary wiring phase sequence of the star-connection high-voltage high-power electric energy quality control device:
1) when the three-phase primary voltage of the power grid is normally connected to the star-connection high-voltage high-power electric energy quality control device, the system can be equivalent to a three-phase diode uncontrolled rectifying circuit after the bypass contactor is switched on, and at the moment, according to the three-phase primary actual voltage of the power grid, the instantaneous maximum absolute value of the power grid voltage and the three-phase input current waveform of the star-connection high-voltage high-power electric energy quality control device: the sequence of the maximum absolute value of the power grid voltage is + Uab，-Uca，+Ubc，-Uab，+Uca，-UbcWhen the grid voltage is connected in a positive sequence, the three-phase voltage can be divided into the 6 sections in one period and sequentially and circularly appear according to the sequence, and the current waveform of the star-connected high-voltage high-power electric energy quality control device is as follows: if the instantaneous value of the defined current is 1 when being larger than zero, 2 when being smaller than zero and 0 when being equal to zero, the three-phase input current direction combination I of the star-connected high-voltage high-power electric energy quality control deviceaIbIcThe corresponding relations in the six time intervals are sequentially (120, 102, 012, 210, 201, 021), and the table forms are shown in the following table 1;
table 1: three-phase input current direction combination and primary voltage peak value corresponding relation of star-connected high-voltage high-power electric energy quality control device
2) The star connects high-power electric energy quality of high pressure to administer the device and finishes precharging and the bypass contactor closes the back short time device three-phase input current impact obviously, because the bypass contactor closes the back short time device three-phase input current impact obviously easily judges, so can judge the device three-phase input current direction combination in this period: if the current impact in 3 sections is obvious after the bypass contactor is switched on, and the three-phase input current direction combination is (021, 120 and 102) in sequence, the result of the three-phase input current direction combination shows that the grid voltage is in positive phase sequence connection and the maximum absolute value of the grid voltage is-U in sequencebc，+Uab，-Uca；
3) Judging according to the input current impact waveform of the star-connected high-voltage high-power electric energy quality control device in a short time after the bypass contactor is switched on: if the three-phase input current direction combination is (012, 102, 120) in sequence, the grid voltage is connected in a negative phase sequence; at the moment, the control system can prompt that the error of the primary wiring phase sequence requires a constructor to adjust primary wiring or adjust the phase sequence of the B phase and the C phase in the control system; if the B-phase and C-phase sampling and control signals are exchanged and adjusted in the control system, the three-phase input current direction combination shifts (021, 120 and 102) after the adjustment is finished, and the system restores to positive phase sequence wiring.
3. The method for identifying the power grid signal of the star-connected high-voltage high-power quality control device according to claim 1, wherein the second step specifically comprises the following steps:
after the primary wiring of the three-phase input voltage is intelligently identified, the input current I of the equipment in the pre-charging process of the device needs to be reusedca、IcbAnd IccThe impulse current direction carries out intelligent identification and judgment to the three-phase voltage PT sampling signal wiring of the star-connection high-voltage high-power electric energy quality control device:
according to the combined result of the input current directions of the star-connection high-voltage high-power quality control device when the corrected grid voltage is subjected to one-time positive phase sequence wiring, the instantaneous maximum value sequence relation of the grid voltage can be confirmed, and intelligent identification and judgment can be performed on grid voltage three-phase PT sampling signals by comparing the grid voltage PT signal sampling results;
1) if the star-connected high-voltage high-power electric energy quality control device accords with the three-phase input current and the three-phase power grid voltage sampling PT signal in a short time after the bypass contactor is switched on: the three-phase input current direction combination of the star-connected high-voltage high-power electric energy quality control device is (021, 120 and 102) in sequence, and the occurrence sequence of the instantaneous maximum values of the power grid voltage is-U in sequencebc，+Uab，-Uca；
The maximum values of the grid voltage PT sampling signals corresponding to the three-phase input current impact waveforms sequentially appear in an order of-U23，+U12，-U31(ii) a Is composed of-Ubc＝-U23Equation U can be derivedb-Uc＝U2-U3And is composed of + Uab＝+U12Then equation U can be obtaineda-Ub＝U1-U2Then is made of-Uca＝-U31Can obtain Uc-Ua＝U3-U1Simultaneous three equations to obtain a system of equations
The three-phase grid voltage also satisfies the relation of three-phase voltage sum being zero without considering the influence of zero sequence voltage, i.e. the three-phase grid voltage
The correct phase corresponding relation of the PT sampling signals of the three-phase power grid voltage can be obtained by simultaneously solving the two equation sets
According to the intelligent recognition result, the power grid voltage PT signal is accurately wired, and the PT signal is correctly corresponding to the actual three-phase voltage one-time wiring;
2) if the star-connected high-voltage high-power electric energy quality control device accords with the three-phase input current and the three-phase power grid voltage sampling PT signal in a short time after the bypass contactor is switched on: the three-phase input current direction combinations of the star-connected high-voltage high-power electric energy quality control device are respectively (021, 120 and 102), and the occurrence sequence of the instantaneous maximum values of the network voltage is-Ubc，+Uab，-Uca；
The maximum value of the grid voltage PT sampling signals corresponding to the three-phase input current impact waveform sequentially appears in a sequence of + U12，-U31，+U23(ii) a Then is composed of-Ubc＝+U12Equation U can be derivedb-Uc＝-U1+U2And is composed of + Uab＝-U31Then equation U can be obtaineda-Ub＝U1-U3Then is made of-Uca＝+U23Can obtain Ua-Uc＝U2-U3Simultaneous three equations to obtain a system of equations
The three-phase grid voltage also satisfies the relation of three-phase voltage sum being zero without considering the influence of zero sequence voltage, i.e. the three-phase grid voltage
The correct phase corresponding relation of the PT sampling signals of the three-phase power grid voltage can be obtained by simultaneously solving the two equation sets
According to the intelligent recognition result, the power grid voltage PT signal homonymous terminal connection error can be known, and meanwhile, the corresponding relation between the three-phase PT signal and the power grid voltage primary connection is abnormal; the star-connected high-voltage high-power electric energy quality control device control system can give prompt information according to the intelligent identification result of the grid voltage PT sampling signals to require constructors to adjust the PT signal wiring, and can also automatically adjust the grid voltage PT sampling signals in the control system to restore the corresponding relation between the grid voltage PT sampling signals and the grid voltage primary wiring.
4. The grid signal identification method of the star-connected high-voltage high-power quality control device according to claim 1, wherein the fourth step specifically comprises the following steps:
according to the electrical connection principle of the star connection high-voltage high-power quality control device, the following relations exist between the power grid current and the load current and between the star connection high-voltage high-power quality control device input current:
the star-connected high-voltage high-power quality control device can be started and input current of the star-connected high-voltage high-power quality control device changes in step by utilizing the current relation formula, and the following relation between the power grid current and the input current of the star-connected high-voltage high-power quality control device can be obtained because the load current is not obviously changed in a short time of the input current step of the star-connected high-voltage high-power quality control device;
by utilizing the formula, when the input current of the star-connected high-voltage high-power electric energy quality treatment device changes in step, the corresponding relation between the grid current CT sampling signal and the input current phase of the star-connected high-voltage high-power electric energy quality treatment device can be easily identified by respectively calculating the change of the input current and the grid current of the star-connected high-voltage high-power electric energy quality treatment device, so that the intelligent identification of the grid current CT sampling signal is realized, and the wiring prompt of the grid current CT sampling signal can be provided to field constructors according to the intelligent identification algorithm result or the automatic adjustment operation of the grid current CT sampling signal can be carried out in a control system of the star-connected high-voltage high-power electric energy.
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