CN112398135B - Control method and device for multi-port power electronic transformer of anti-electromagnetic ring network - Google Patents
Control method and device for multi-port power electronic transformer of anti-electromagnetic ring network Download PDFInfo
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- CN112398135B CN112398135B CN202011377244.3A CN202011377244A CN112398135B CN 112398135 B CN112398135 B CN 112398135B CN 202011377244 A CN202011377244 A CN 202011377244A CN 112398135 B CN112398135 B CN 112398135B
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- 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
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/04—Circuit arrangements for ac mains or ac distribution networks for connecting networks of the same frequency but supplied from different sources
- H02J3/06—Controlling transfer of power between connected networks; Controlling sharing of load between connected networks
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- Charge And Discharge Circuits For Batteries Or The Like (AREA)
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Abstract
The application provides a control method and a device of a multiport power electronic transformer of an anti-electromagnetic ring network, wherein the method comprises the following steps: converting a control mode of the multi-port power electronic transformer into constant current control; and in a power supply mode, the control mode is switched regularly, whether the electromagnetic looped network appears in the operation is monitored actively in real time, and the damage to the system operation caused by the electromagnetic looped network for a long time is reduced. In the charging mode, the problem that the low-voltage side charging logic and the anti-electromagnetic ring network logic conflict is solved.
Description
Technical Field
The application relates to the technical field of power control, in particular to a control method and a device of a multiport power electronic transformer of an anti-electromagnetic ring network.
Background
In a power distribution network, when a multi-port power electronic transformer is used for power supply, two working modes exist, wherein the first working mode is a charging mode, and the multi-port power electronic transformer is started by charging through a low-voltage alternating current power grid; the second is a power mode, the multi-port power electronic transformer provides power to the low side load.
When the multi-port power electronic transformer is charged and started by the low-voltage alternating-current side power supply or the low-voltage alternating-current power grid, the multi-port power electronic transformer is generally charged by utilizing a networking breaker to close, namely, a network side switch and a line incoming switch are required to be simultaneously closed, and the operation conflicts with the switch logic of the electromagnetic ring network in the power distribution network, so that the low-voltage side charging cannot be executed, or the power distribution network cannot keep the original switch logic after the low-voltage side charging is executed.
In addition, in the power supply mode, the low-voltage side of the multi-port power electronic transformer is in an off-grid working mode, and as the distribution network is required to be incapable of forming an electromagnetic ring network crossing voltage levels, the power electronic transformer and the adjacent alternating current transformer are required to be incapable of running in parallel. In actual operation, if an abnormal switching-on or switching-off is caused by the fact that an alternating current breaker or a networking breaker is in abnormal switching-on or a worker touches the switching-on by hand by mistake, the power electronic transformer and the low-voltage side of the adjacent alternating current transformer are not planned to operate in parallel, an electromagnetic looped network is formed, and great harm is caused to system operation.
Disclosure of Invention
Aiming at the problems in the prior art, the application provides a control method and a control device for a multi-port power electronic transformer of an anti-electromagnetic ring network, which can at least partially solve the problems in the prior art.
In order to achieve the above purpose, the present application adopts the following technical scheme:
in a first aspect, a control method of a multi-port power electronic transformer of an anti-electromagnetic ring network is provided, including:
converting a control mode of the multi-port power electronic transformer into constant current control;
and actively monitoring whether the multiport power electronic transformer and the low-voltage side of the adjacent alternating-current transformer form an electromagnetic ring network in real time, and controlling the transformer according to the monitoring result.
Further, the real-time active monitoring of whether the multiport power electronic transformer forms an electromagnetic ring network with the low-voltage side of the adjacent ac transformer and performing transformer control according to the monitoring result includes:
injecting a preset offset component into the control current of the multi-port power electronic transformer;
judging whether the phase difference between the voltage at the side of the system and the voltage at the side of the system is larger than the fixed value of the electromagnetic ring network or not;
if not, continuing to inject a preset offset component into the control current of the multi-port power electronic transformer;
judging whether the phase difference between the voltage at the side of the system and the voltage at the side of the system is larger than the fixed value of the electromagnetic ring network or not;
if the phase difference between the voltage at the side of the system and the voltage at the side of the system is not more than the fixed value of the electromagnetic ring network, the network switch is controlled to be disconnected and/or the power electronic transformer is locked;
if the phase difference between the voltage at the side of the multi-port power electronic transformer and the voltage at the side of the system is judged to be larger than the fixed value of the electromagnetic ring network at any time, the control mode of the multi-port power electronic transformer is switched back to the fixed voltage control so that the multi-port power electronic transformer continues to supply power for the power load at the low voltage side.
Further, the controlling to trip the networking switch and/or to latch the power electronic transformer comprises:
tripping the networking switch after delaying the first preset delay;
continuously judging whether the phase difference between the voltage at the side of the electromagnetic loop network and the voltage at the side of the system is larger than a fixed value of the electromagnetic loop network;
if not, locking the power electronic transformer after delaying the second preset time delay.
Further, the control method of the multi-port power electronic transformer of the anti-electromagnetic ring network further comprises the following steps:
DQ conversion is adopted to obtain a local side voltage vector and a system side voltage vector;
and comparing the current side voltage vector with the system side voltage vector to obtain the phase difference between the current side voltage and the system side voltage.
Further, the converting the control mode of the multi-port power electronic transformer into constant current control includes:
the control mode of the multiport power electronic transformer is converted into constant current control according to the preset time interval timing;
the preset time interval is smaller than the set time of the short-time electromagnetic looped network permitted by the power distribution network.
Further, the control method of the multi-port power electronic transformer of the anti-electromagnetic ring network further comprises the following steps:
and combining the low-voltage side charging logic with the protection logic of the anti-electromagnetic ring network to control the multi-port power electronic transformer to start the low-voltage side charging.
Further, the combining the low-voltage side charging logic with the protection logic of the anti-electromagnetic ring network controls the multi-port power electronic transformer to perform low-voltage side charging, including:
releasing the electric lock according to the low-voltage side charging instruction and exiting the dual-power mutual standby mode;
the multi-port power electronic transformer is controlled to charge the low-voltage side after the third preset time delay, and the rectification mode of the low-voltage side DC-AC converter of the power electronic transformer is controlled to operate;
when the multi-port power electronic transformer is started, controlling the multi-port power electronic transformer to be charged from a low-voltage side to be converted into a high-voltage side for power supply, and controlling a low-voltage side DC-AC converter of the power electronic transformer to perform inversion grid-connected operation;
the fourth preset time delay is carried out, and the inversion off-grid operation of the DC-AC converter at the low voltage side of the power electronic transformer is controlled;
when the low-voltage side DC-AC converter of the power electronic transformer performs inversion off-grid operation, the power electronic transformer is put into electric locking and returns to a standby mode of dual power supplies.
Further, the combination of the low-voltage side charging logic and the protection logic of the anti-electromagnetic ring network controls the multi-port power electronic transformer to charge the low-voltage side, and the method further comprises the following steps:
and acquiring a low-voltage side charging instruction issued by a background.
In a second aspect, an electronic device is provided, including a memory, a processor, and a computer program stored on the memory and executable on the processor, where the processor implements the steps of the method for controlling a multiport power electronic transformer of an anti-electromagnetic ring network described above when the program is executed.
In a third aspect, a computer readable storage medium is provided, on which a computer program is stored, which computer program, when being executed by a processor, implements the steps of the method for controlling a multiport power electronic transformer of an anti-electromagnetic ring network as described above.
The application provides a control method and a device of a multiport power electronic transformer of an anti-electromagnetic ring network, wherein the method comprises the following steps: converting a control mode of the multi-port power electronic transformer into constant current control; and in a power supply mode, the control mode is switched regularly, whether the electromagnetic looped network appears in the operation is monitored actively in real time, and the damage to the system operation caused by the electromagnetic looped network for a long time is reduced. In the charging mode, the problem that the low-voltage side charging logic and the anti-electromagnetic ring network logic conflict is solved.
In another aspect, the method further comprises: the low-voltage side charging logic is combined with the protection logic of the anti-electromagnetic ring network to control the multi-port power electronic transformer to charge the low-voltage side, so that the problem of conflict with the electromagnetic ring network locking and power supply standby functions is solved when the low-voltage side of the power electronic transformer is started in a charging mode.
The foregoing and other objects, features and advantages of the application will be apparent from the following more particular description of preferred embodiments, as illustrated in the accompanying drawings.
Drawings
In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings that are required in the embodiments or the description of the prior art will be briefly described, and it is obvious that the drawings in the following description are some embodiments of the present application, and other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art. In the drawings:
FIG. 1 is a schematic diagram of a primary connection of a multi-port power electronic transformer;
fig. 2 is a schematic flow chart of a control method of a multi-port power electronic transformer of an anti-electromagnetic ring network according to an embodiment of the present application;
FIG. 3 shows specific steps of step S200 in an embodiment of the application;
FIG. 4 illustrates a transformer control flow for a power mode in an embodiment of the application;
fig. 5 is a flowchart of a control method of a multi-port power electronic transformer of an anti-electromagnetic ring network according to an embodiment of the present application;
FIG. 6 shows specific steps of step S300 in an embodiment of the application;
FIG. 7 illustrates a transformer control flow in a low-charge mode in an embodiment of the application;
fig. 8 is a block diagram of a control device of a multi-port power electronic transformer of an anti-electromagnetic ring network in an embodiment of the present application;
fig. 9 is a block diagram of an electronic device according to an embodiment of the present application.
Detailed Description
In order that those skilled in the art will better understand the present application, a technical solution in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in which it is apparent that the described embodiments are only some embodiments of the present application, not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the present application without making any inventive effort, shall fall within the scope of the present application.
It will be appreciated by those skilled in the art that embodiments of the present application may be provided as a method, system, or computer program product. Accordingly, the present application may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Furthermore, the present application may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, and the like) having computer-usable program code embodied therein.
It is noted that the terms "comprises" and "comprising," and any variations thereof, in the description and claims of the present application and in the foregoing figures, are intended to cover a non-exclusive inclusion, such that a process, method, system, article, or apparatus that comprises a list of steps or elements is not necessarily limited to those steps or elements expressly listed or inherent to such process, method, article, or apparatus.
It should be noted that, without conflict, the embodiments of the present application and features of the embodiments may be combined with each other. The application will be described in detail below with reference to the drawings in connection with embodiments.
FIG. 1 is a schematic diagram of a primary connection of a multi-port power electronic transformer; the power electronic transformer comprises four ports, namely, an alternating-current medium voltage of 10kV and a low-voltage of 380V, and a direct-current of +/-10 kV and +/-375V, wherein the number of the ports and the voltage level can be changed correspondingly according to actual engineering requirements. The 1# main transformer is changed into a conventional alternating current transformer, the 2# transformer is a power electronic transformer, the 1# transformer and the power electronic transformer supply power for a low-voltage alternating current load at the same time, and the two transformers are operated in a split mode, namely, a 10kV breaker K13 and a 380V breaker K3 are in an off state, no electrical connection exists between the two transformers, and the two transformers are supplied with power with loads respectively.
In the power electronic transformer charging mode, the low-voltage side charging is started or restarted, an alternating current 380V power supply is required for charging, a 380V breaker K3 is required to be combined at the moment, and the alternating current system supplies power for the power electronic transformer. Because the configuration of the electromagnetic-proof ring network of the alternating current system is provided with an electric lock, three circuit breakers K1, K2 and K3 are not allowed to be simultaneously combined in, and the electric lock conflicts with the charging function of the low-voltage side of the power electronic transformer.
In the power electronic transformer power supply mode, the low-voltage side DC-AC converter inverts off-grid operation to supply power for loads, the segmented breaker K3 is in a brake-off state, and the low-voltage side DC-AC converter controls the voltage and frequency of alternating current 380V to be in a constant alternating current voltage control mode. Under the working state, the operation requirement of the distribution network does not allow the low-voltage sides of the two distribution transformers to be parallel, so that a large-scale electromagnetic looped network is formed, and the safe operation of the power network is affected.
According to the embodiment of the application, the low-voltage side charging logic is combined with the protection logic of the anti-electromagnetic ring network, the low-voltage alternating-current side of the power electronic transformer and the low-voltage side of the adjacent conventional transformer are mutually used as backup power supplies, the problem of conflict between low-voltage side charging and switching logic of the anti-electromagnetic ring network is solved, the requirement of low-voltage side charging of the power electronic transformer is met, and the protection measures of the anti-electromagnetic ring network of the power distribution network can be reliably restored after charging, so that the power electronic transformer and the power supply of the power grid system are mutually used, and the power supply reliability is improved; in addition, the running state of the system is actively detected in real time, after the unplanned parallel running is found, the networking switch is tripped through a time limit, and the power electronic transformer is locked through a two-time limit, so that the running risk of the electromagnetic ring network of the power distribution network can be effectively reduced.
Fig. 2 is a schematic flow chart of a control method of a multi-port power electronic transformer of an anti-electromagnetic ring network according to an embodiment of the present application; as shown in fig. 2, the control method of the multi-port power electronic transformer may include the following:
step S100: converting a control mode of the multi-port power electronic transformer into constant current control;
the normal power supply mode is constant voltage control, the control mode is firstly converted into constant current control, and the current reference set point tracks the load current during the constant voltage control so as to ensure that disturbance does not occur in switching.
Step S200: and actively monitoring whether the multiport power electronic transformer and the low-voltage side of the adjacent alternating-current transformer form an electromagnetic ring network in real time, and controlling the transformer according to the monitoring result.
Specifically, a voltage offset method can be used for actively monitoring whether the multiport power electronic transformer forms an electromagnetic ring network with the low-voltage side of an adjacent alternating-current transformer in real time, and transformer control is performed according to the monitoring result.
After switching, a phase shift delta theta is added to the control current to make the control current phase-different from the previous working current. And judging whether an electromagnetic ring network is formed or not based on the phase difference, and adopting a corresponding control means according to a judging result so as to solve the problem of the electromagnetic ring network.
In summary, the control method of the multi-port power electronic transformer of the anti-electromagnetic ring network provided by the embodiment of the application is characterized in that in a power supply mode, the control mode is switched regularly, and whether the electromagnetic ring network appears in the operation is actively monitored in real time by adopting a voltage offset method.
In an alternative embodiment, referring to fig. 3, this step S200 may include the following:
step S210: injecting a preset offset component into the control current of the multi-port power electronic transformer;
wherein, by adding a phase shift delta theta to the control current, the control current is caused to have a phase difference with the previous working current. If the power electronic device is in an off-grid state, the current offset will cause the phase of the low-voltage side voltage of the power electronic device to be offset.
Step S220: judging whether the phase difference between the voltage at the side of the system and the voltage at the side of the system is larger than the fixed value of the electromagnetic ring network or not;
if not, go to step S230; if yes, go to step S260.
If so, judging that the electromagnetic ring network does not exist at present, and still being in an off-network operation mode, switching a control mode into constant alternating voltage control before disturbance occurs to the system, and continuously supplying power to the load; if not, an electromagnetic ring network may exist.
Step S230: continuing to inject a preset offset component into the control current of the multi-port power electronic transformer;
in this case, the potential difference is increased by continuing to add the current component of the offset phase Δθ in the constant current mode.
Step S240: judging whether the phase difference between the voltage at the side of the system and the voltage at the side of the system is larger than the fixed value of the electromagnetic ring network or not;
if not, executing step S250; if yes, go to step S260.
If so, judging that the electromagnetic ring network does not exist at present, and still being in an off-network operation mode, switching a control mode into constant alternating voltage control before disturbance occurs to the system, and continuously supplying power to the load; if not, an electromagnetic ring network may exist.
Step S250: controlling the trip networking switch and/or latching the power electronic transformer;
specifically, delaying the time T1, judging that the electromagnetic ring network operation occurs, and tripping a breaking breaker K3; and continuously detecting the voltage phase, if the phase difference is still smaller than a fixed value, delaying for T2 time, judging that the electromagnetic ring network still cannot be eliminated at the moment, and controlling the locking of the DC-AC converter at the low voltage side and the tripping of the incoming line breaker K2.
Namely: tripping the networking switch after delaying the first preset delay; continuously judging whether the phase difference between the voltage at the side of the electromagnetic loop network and the voltage at the side of the system is larger than a fixed value of the electromagnetic loop network; if not, locking the power electronic transformer after delaying the second preset time delay; if yes, go to step S260.
Step S260: and switching the control mode of the multi-port power electronic transformer back to constant voltage control so that the multi-port power electronic transformer continues to supply power for the low-voltage side power load.
It is worth to be noted that, in the above steps, the current deviation may cause a voltage deviation, and the phase difference may be obtained by comparing the voltage vector deviation, and particularly, the DQ conversion is adopted to obtain the current side voltage vector and the system side voltage vector; and comparing the current side voltage vector with the system side voltage vector to obtain the phase difference between the current side voltage and the system side voltage.
It is noted that, a phase-locked loop (PLL) for monitoring the system voltage, determining phasors of the system voltage in the DQ coordinate system after DQ conversion according to the system voltage; a system for monitoring the low side voltage of the power electronic transformer for extracting voltage phasors by DQ conversion; detecting the voltage phase difference of the two systems, and judging whether the two systems are in an electromagnetic ring network state or not; and K3, K2 circuit breaker tripping function and power transformer low-voltage side DC-AC converter locking function.
In an alternative embodiment, the step S100 includes: and (3) converting the control mode of the multi-port power electronic transformer into constant current control according to the preset time interval.
It is worth to say that, in the off-grid operation working state, the low-voltage side DC-AC converter normally works as a fixed alternating voltage control mode, and the electromagnetic ring network detection program is carried out at intervals of preset time. The preset time interval can be set manually, and the setting principle is smaller than the set time of the short-time electromagnetic ring network allowed by the power distribution network.
In order to enable those skilled in the art to better understand the present application, a transformer control flow of the power supply mode in the embodiment of the present application will be described with reference to fig. 4:
in order to prevent a large-range electromagnetic ring network from appearing, the system monitors the working state of the low-voltage side DC-AC converter and prevents the working condition of abnormal closing of the segmented circuit breaker K3, and the system specifically comprises the following steps:
the detection program of the anti-electromagnetic ring network comprises the following steps:
1. entering an electromagnetic ring network detection program at intervals of t 3;
2. converting the control mode into constant current control;
3. injecting a delta theta offset component into the current to enable the current to have a phase difference;
4. comparing the phase difference between the low voltage side (i.e., the present side voltage) of the DCAC and the system side voltage (i.e., the system voltage of the phase locked loop);
5. judging that the phase difference is larger than the electromagnetic ring net fixed value?
The DQ conversion is adopted to compare the voltage of the local side with the system voltage phasor of the phase-locked loop, and whether a phase difference exists or not is judged;
6. if the phase difference is larger than the fixed value, the electromagnetic ring network does not appear;
7. switching back to the constant voltage control mode to continue power supply;
and switching back to the constant voltage control mode before the system is disturbed, and continuing to supply power.
8. If the phase difference is smaller than a fixed value, an electromagnetic ring network may appear;
9. continuously injecting a delta theta offset component into the current to enlarge the current phase difference;
10. comparing the phase difference between the DCAC low-voltage side and the system side voltage;
11. judging that the phase difference is larger than the electromagnetic ring net fixed value?
If yes, no electromagnetic ring network exists; if not, after the time delay T1, tripping the segmented breaker K3, namely tripping the networking switch, and returning to the step of continuously injecting a delta theta offset component into the current; again, determine that the phase difference is greater than the electromagnetic ring net constant? If not, delaying the time T2, and controlling the locking of the low-voltage side DC-AC converter and the tripping of the incoming line breaker K2, namely locking the power electronic transformer.
In an alternative embodiment, referring to fig. 5, the method for controlling the multi-port power electronic transformer of the anti-electromagnetic ring network further includes:
step S300: and combining the low-voltage side charging logic with the protection logic of the anti-electromagnetic ring network to control the multi-port power electronic transformer to start the low-voltage side charging.
Specifically, referring to fig. 6, this step S300 may include the following:
step S310: releasing the electric lock according to the low-voltage side charging instruction and exiting the dual-power mutual standby mode;
after detecting a low-voltage side charging instruction issued by the background, starting a charging logic, releasing the low-voltage side electric locking function, allowing three circuit breakers to be simultaneously combined in, and exiting the two-way power supply to be a standby function.
Step S320: the multi-port power electronic transformer is controlled to charge the low-voltage side after the third preset time delay, and the rectification mode of the low-voltage side DC-AC converter of the power electronic transformer is controlled to operate;
after unlocking is completed, the sectionalizer K3 and the power electronic transformer incoming line breaker K2 are combined for low-voltage side charging after a preset time delay, and a rectification mode of a low-voltage side DC-AC converter (short for low-voltage DCAC) of the power electronic transformer is instructed to operate.
Step S330: when the multi-port power electronic transformer is started, controlling the multi-port power electronic transformer to be charged from a low-voltage side to be converted into a high-voltage side for power supply, and controlling a low-voltage side DC-AC converter of the power electronic transformer to perform inversion grid-connected operation;
specifically, after the power electronic transformer is started, the low-voltage side DC-AC converter is converted into inverter grid-connected operation, and is in a short-time electromagnetic ring network state.
Step S340: the fourth preset time delay is carried out, and the inversion off-grid operation of the DC-AC converter at the low voltage side of the power electronic transformer is controlled;
after another preset time delay, the application separates the sectionalized breaker K3 and makes the low-voltage side DC-AC converter turn to off-grid operation to be in a constant voltage control mode.
Step S350: when the low-voltage side DC-AC converter of the power electronic transformer performs inversion off-grid operation, the power electronic transformer is put into electric locking and returns to a standby mode of dual power supplies.
After the off-grid running state is detected to be recovered, the low-voltage circuit breaker is put into electrical linkage, the electromagnetic-proof ring network function is recovered, and the 1# transformer and the 2# transformer are put into a standby power supply function.
By adopting the technical scheme, in the charging mode, when the low-voltage side of the power electronic transformer is started, the problem of conflict with the electromagnetic ring network locking and power supply standby functions is solved.
In order to enable those skilled in the art to better understand the present application, a specific description is given of a transformer control flow of the charging mode in an embodiment of the present application with reference to fig. 7:
the method comprises the following steps:
s1, performing low-voltage side charging or restarting;
s2, releasing the electric lock, and exiting the standby function of the dual power supplies;
s3, delaying t1 to be combined into a K3 circuit breaker;
s4, combining a K2 circuit breaker;
thereby, the multiport power electronic transformer is controlled to perform low-side charging.
S5, the low-voltage side DC-AC converter operates in a rectifying mode;
s6, combining a K15 circuit breaker;
i.e. after charging is completed, the high-side switch K15 is turned on to supply the power electronic transformer with the high-side power supply.
S7, locking the low-voltage side DC-AC converter;
i.e. the low side power supply is stopped.
S8, unlocking a high-voltage part of the power electronic transformer;
s9, the low-voltage side DC-AC converter performs inversion grid-connected operation;
s10, separating a K3 circuit breaker by a time delay t 2;
s11, the low-voltage side DC-AC converter performs inversion off-grid operation;
s12, switching in electric locking and dual power supply are standby functions.
Based on the same inventive concept, the embodiment of the application also provides a control device of the multi-port power electronic transformer of the anti-electromagnetic ring network, which can be used for realizing the method described in the embodiment, as described in the following embodiment. The principle of solving the problem of the control device of the multi-port power electronic transformer of the anti-electromagnetic ring network is similar to that of the method, so that the implementation of the control device of the multi-port power electronic transformer of the anti-electromagnetic ring network can be seen from the implementation of the method, and the repetition is omitted. As used below, the term "unit" or "module" may be a combination of software and/or hardware that implements the intended function. While the means described in the following embodiments are preferably implemented in software, implementation in hardware, or a combination of software and hardware, is also possible and contemplated.
Fig. 8 is a block diagram of a control device of a multiport power electronic transformer of an anti-electromagnetic ring network in an embodiment of the present application. As shown in fig. 8, the control device of the multi-port power electronic transformer of the electromagnetic-proof ring network specifically includes: the mode switch module 10 and the monitoring control module 20 are controlled.
The control mode conversion module 10 converts a control mode of the multi-port power electronic transformer into constant current control;
the monitoring control module 20 actively monitors whether the multi-port power electronic transformer forms an electromagnetic ring network with the low-voltage side of the adjacent alternating current transformer in real time and performs transformer control according to the monitoring result.
In summary, the control device for the multi-port power electronic transformer of the electromagnetic ring network is provided by the embodiment of the application, in a power supply mode, the control mode is switched regularly, and a voltage offset method is adopted to actively monitor whether the electromagnetic ring network appears in operation in real time.
In an alternative embodiment, the monitoring control module includes: the device comprises an offset component injection unit, a judging unit, an offset component secondary injection unit, a secondary judging unit, a first control unit and a second control unit.
The offset component injection unit injects a preset offset component into the control current of the multi-port power electronic transformer;
the judging unit judges whether the phase difference between the voltage at the side of the electromagnetic loop network and the voltage at the side of the system is larger than a fixed value of the electromagnetic loop network or not;
the offset component secondary injection unit is used for continuously injecting a preset offset component into the control current of the multi-port power electronic transformer if the phase difference between the voltage at the side of the multi-port power electronic transformer and the voltage at the side of the system is not greater than the fixed value of the electromagnetic ring network;
the secondary judging unit judges whether the phase difference between the voltage at the side of the secondary judging unit and the voltage at the side of the system is larger than the fixed value of the electromagnetic ring network or not;
the first control unit is used for controlling the tripping of the networking switch and/or locking the power electronic transformer if the phase difference between the voltage at the side of the first control unit and the voltage at the side of the system is judged to be not more than the fixed value of the electromagnetic ring network again;
and the second control unit is used for switching the control mode of the multi-port power electronic transformer back to the fixed voltage control if any one of the second control unit judges that the phase difference between the voltage at the side of the multi-port power electronic transformer and the voltage at the side of the system is larger than the fixed value of the electromagnetic ring network so as to enable the multi-port power electronic transformer to continuously supply power for the low-voltage side power load.
In an alternative embodiment, the first control unit comprises: the first delay control subunit, the judging subunit and the second delay control subunit.
The first delay control subunit is used for switching off the networking switch after delaying the first preset delay;
the judging subunit continuously judges whether the phase difference between the voltage at the side of the main power supply and the voltage at the side of the system is larger than the fixed value of the electromagnetic ring network;
and the second delay control subunit delays the second preset delay to lock the power electronic transformer if the phase difference between the voltage at the side of the power electronic transformer and the voltage at the side of the system is not larger than the fixed value of the electromagnetic ring network.
In an alternative embodiment, the control device of the multi-port power electronic transformer of the anti-electromagnetic ring network further comprises: DQ conversion module and phase difference acquisition module.
The DQ conversion module is used for obtaining a local side voltage vector and a system side voltage vector by adopting DQ conversion;
and the phase difference acquisition module is used for comparing the current side voltage vector with the system side voltage vector to obtain the phase difference between the current side voltage and the system side voltage.
In an alternative embodiment, the control mode conversion module includes: and the timing conversion unit is used for converting the control mode of the multi-port power electronic transformer into constant current control according to the preset time interval timing.
In an alternative embodiment, the preset time interval is less than a prescribed time for which the distribution network allows short-time electromagnetic ring networks.
In an alternative embodiment, the control device of the multi-port power electronic transformer of the anti-electromagnetic ring network further comprises: and the low-voltage side charging starting module combines the low-voltage side charging logic with the protection logic of the anti-electromagnetic ring network to control the multi-port power electronic transformer to start the low-voltage side charging.
In an alternative embodiment, the low side charge start module includes: the system comprises a locking mode control unit, a charging control unit, a power supply control unit, an inversion off-grid operation delay control unit and a standby mode conversion unit.
A locking mode control unit for releasing the electric locking according to the low-voltage side charging instruction and exiting the dual-power mutual standby mode;
the charging control unit is used for controlling the multi-port power electronic transformer to charge the low-voltage side after delaying a third preset time delay and controlling the low-voltage side DC-AC converter of the power electronic transformer to operate in a rectifying mode;
the power supply control unit is used for controlling the multi-port power electronic transformer to be charged from a low-voltage side to be converted into a high-voltage side for power supply after the multi-port power electronic transformer is started, and controlling the low-voltage side DC-AC converter of the power electronic transformer to perform inversion grid-connected operation;
the inversion off-grid operation delay control unit delays a fourth preset delay to control the inversion off-grid operation of the DC-AC converter at the low voltage side of the power electronic transformer;
and the standby mode conversion unit is used for switching into an electric locking mode and recovering the dual power supplies to be in a standby mode after the DC-AC converter at the low voltage side of the power electronic transformer performs inversion off-grid operation.
In an alternative embodiment, the low side charge start module further comprises: the instruction acquisition unit acquires a low-voltage side charging instruction issued by the background.
The apparatus, module or unit set forth in the above embodiments may be implemented in particular by a computer chip or entity, or by a product having a certain function. A typical implementation device is an electronic device, which may be, for example, a personal computer, a laptop computer, a cellular telephone, a camera phone, a smart phone, a personal digital assistant, a media player, a navigation device, an email device, a game console, a tablet computer, a wearable device, or a combination of any of these devices.
In a typical example the electronic device comprises in particular a memory, a processor and a computer program stored on the memory and executable on the processor, said processor implementing the steps of the method for controlling a multiport power electronic transformer of an anti-electromagnetic ring network described above when said program is executed.
Referring now to fig. 9, a schematic diagram of an electronic device 600 suitable for use in implementing embodiments of the present application is shown.
As shown in fig. 9, the electronic apparatus 600 includes a Central Processing Unit (CPU) 601, which can perform various appropriate works and processes according to a program stored in a Read Only Memory (ROM) 602 or a program loaded from a storage section 608 into a Random Access Memory (RAM)) 603. In the RAM603, various programs and data required for the operation of the system 600 are also stored. The CPU601, ROM602, and RAM603 are connected to each other through a bus 604. An input/output (I/O) interface 605 is also connected to bus 604.
The following components are connected to the I/O interface 605: an input portion 606 including a keyboard, mouse, etc.; an output portion 607 including a Cathode Ray Tube (CRT), a Liquid Crystal Display (LCD), and the like, a speaker, and the like; a storage section 608 including a hard disk and the like; and a communication section 609 including a network interface card such as a LAN card, a modem, or the like. The communication section 609 performs communication processing via a network such as the internet. The drive 610 is also connected to the I/O interface 605 as needed. Removable media 611 such as a magnetic disk, an optical disk, a magneto-optical disk, a semiconductor memory, or the like is mounted on drive 610 as needed, so that a computer program read therefrom is mounted as needed as storage section 608.
In particular, according to embodiments of the present application, the processes described above with reference to flowcharts may be implemented as computer software programs. For example, an embodiment of the present application includes a computer-readable storage medium having stored thereon a computer program which, when executed by a processor, performs the steps of the method for controlling a multiport power electronic transformer of an anti-electromagnetic ring network described above.
In such an embodiment, the computer program may be downloaded and installed from a network through the communication portion 609, and/or installed from the removable medium 611.
Computer readable media, including both non-transitory and non-transitory, removable and non-removable media, may implement information storage by any method or technology. The information may be computer readable instructions, data structures, modules of a program, or other data. Examples of storage media for a computer include, but are not limited to, phase change memory (PRAM), static Random Access Memory (SRAM), dynamic Random Access Memory (DRAM), other types of Random Access Memory (RAM), read Only Memory (ROM), electrically Erasable Programmable Read Only Memory (EEPROM), flash memory or other memory technology, compact disc read only memory (CD-ROM), digital Versatile Discs (DVD) or other optical storage, magnetic cassettes, magnetic tape magnetic disk storage or other magnetic storage devices, or any other non-transmission medium, which can be used to store information that can be accessed by a computing device. Computer-readable media, as defined herein, does not include transitory computer-readable media (transmission media), such as modulated data signals and carrier waves.
For convenience of description, the above devices are described as being functionally divided into various units, respectively. Of course, the functions of each element may be implemented in the same piece or pieces of software and/or hardware when implementing the present application.
The present application is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems) and computer program products according to embodiments of the application. It will be understood that each flow and/or block of the flowchart illustrations and/or block diagrams, and combinations of flows and/or blocks in the flowchart illustrations and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
It should also be noted that the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one … …" does not exclude the presence of other like elements in a process, method, article or apparatus that comprises the element.
It will be appreciated by those skilled in the art that embodiments of the present application may be provided as a method, system, or computer program product. Accordingly, the present application may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Furthermore, the present application may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, and the like) having computer-usable program code embodied therein.
The application may be described in the general context of computer-executable instructions, such as program modules, being executed by a computer. Generally, program modules include routines, programs, objects, components, data structures, etc. that perform particular tasks or implement particular abstract data types. The application may also be practiced in distributed computing environments where tasks are performed by remote processing devices that are linked through a communications network. In a distributed computing environment, where a plurality of computing devices, program modules may be located in both local and remote computer storage media including memory storage devices.
In this specification, each embodiment is described in a progressive manner, and identical and similar parts of each embodiment are all referred to each other, and each embodiment mainly describes differences from other embodiments. In particular, for system embodiments, since they are substantially similar to method embodiments, the description is relatively simple, as relevant to see a section of the description of method embodiments.
The foregoing is merely exemplary of the present application and is not intended to limit the present application. Various modifications and variations of the present application will be apparent to those skilled in the art. Any modification, equivalent replacement, improvement, etc. which come within the spirit and principles of the application are to be included in the scope of the claims of the present application.
Claims (8)
1. A method for controlling a multiport power electronic transformer of an anti-electromagnetic ring network, comprising:
the control mode of the multiport power electronic transformer is converted into constant current control according to the preset time interval timing; the preset time interval is smaller than the set time of the short-time allowed electromagnetic ring network of the power distribution network;
injecting a preset offset component into the control current of the multi-port power electronic transformer;
judging whether the phase difference between the voltage at the side of the system and the voltage at the side of the system is larger than the fixed value of the electromagnetic ring network or not;
if not, continuing to inject a preset offset component into the control current of the multi-port power electronic transformer;
judging whether the phase difference between the voltage at the side of the system and the voltage at the side of the system is larger than the fixed value of the electromagnetic ring network or not;
if the phase difference between the voltage at the side of the system and the voltage at the side of the system is not more than the fixed value of the electromagnetic ring network, the network switch is controlled to be disconnected and/or the power electronic transformer is locked;
if the phase difference between the voltage at the side of the multi-port power electronic transformer and the voltage at the side of the system is judged to be larger than the fixed value of the electromagnetic ring network at any time, the control mode of the multi-port power electronic transformer is switched back to the fixed voltage control so that the multi-port power electronic transformer continues to supply power for the power load at the low voltage side.
2. The method for controlling a multi-port power electronic transformer of an anti-electromagnetic ring network according to claim 1, wherein said controlling the tripping of a networking switch and/or the latching of a power electronic transformer comprises:
tripping the networking switch after delaying the first preset delay;
continuously judging whether the phase difference between the voltage at the side of the electromagnetic loop network and the voltage at the side of the system is larger than a fixed value of the electromagnetic loop network;
if not, locking the power electronic transformer after delaying the second preset time delay.
3. The method for controlling a multi-port power electronic transformer of an anti-electromagnetic ring network of claim 1, further comprising:
DQ conversion is adopted to obtain a local side voltage vector and a system side voltage vector;
and comparing the current side voltage vector with the system side voltage vector to obtain the phase difference between the current side voltage and the system side voltage.
4. The method for controlling a multi-port power electronic transformer of an anti-electromagnetic ring network of claim 1, further comprising:
and combining the low-voltage side charging logic with the protection logic of the anti-electromagnetic ring network to control the multi-port power electronic transformer to start the low-voltage side charging.
5. The method of claim 4, wherein the combining the low-side charging logic with the protection logic of the anti-electromagnetic ring network controls the multi-port power electronic transformer to charge the low-side, comprising:
releasing the electric lock according to the low-voltage side charging instruction and exiting the dual-power mutual standby mode;
the multi-port power electronic transformer is controlled to charge the low-voltage side after the third preset time delay, and the rectification mode of the low-voltage side DC-AC converter of the power electronic transformer is controlled to operate;
when the multi-port power electronic transformer is started, controlling the multi-port power electronic transformer to be charged from a low-voltage side to be converted into a high-voltage side for power supply, and controlling a low-voltage side DC-AC converter of the power electronic transformer to perform inversion grid-connected operation;
the fourth preset time delay is carried out, and the inversion off-grid operation of the DC-AC converter at the low voltage side of the power electronic transformer is controlled;
when the low-voltage side DC-AC converter of the power electronic transformer performs inversion off-grid operation, the power electronic transformer is put into electric locking and returns to a standby mode of dual power supplies.
6. The method of claim 5, wherein the combining the low-side charging logic with the protection logic of the anti-electromagnetic ring network controls the multi-port power electronic transformer to charge the low-side, further comprising:
and acquiring a low-voltage side charging instruction issued by a background.
7. An electronic device comprising a memory, a processor and a computer program stored on the memory and executable on the processor, characterized in that the processor implements the steps of the method for controlling a multiport power electronic transformer of an anti-electromagnetic ring network according to any one of claims 1 to 6 when the program is executed by the processor.
8. A computer readable storage medium having stored thereon a computer program, characterized in that the computer program when executed by a processor realizes the steps of the method for controlling a multiport power electronic transformer of an anti-electromagnetic ring network according to any of claims 1 to 6.
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Citations (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103427414A (en) * | 2013-06-13 | 2013-12-04 | 国家电网公司 | Parameter design method of symmetrical controllable phase shifter |
| CN103503269A (en) * | 2011-05-30 | 2014-01-08 | Abb研究有限公司 | System for distributing electric power to an electrical grid |
| CN203883495U (en) * | 2014-04-15 | 2014-10-15 | 广西电网公司 | Electromagnetic looped network flow monitoring system matched with measure of generator cutting |
| CN104269861A (en) * | 2014-10-13 | 2015-01-07 | 国家电网公司 | Electromagnetic looped network reactive power ring current optimal control method based on flexible looped network controller |
| CN104319765A (en) * | 2014-10-29 | 2015-01-28 | 国家电网公司 | Control method of distributed in-series coupling power flow controller |
| CN105958554A (en) * | 2016-04-29 | 2016-09-21 | 贵州电网有限责任公司电力调度控制中心 | Flexible direct current coordination stability control method applied to electromagnetic loop network |
| CN105978135A (en) * | 2016-06-22 | 2016-09-28 | 清华大学 | Current source-type uninterrupted power switch for AC power distribution system |
| CN106803679A (en) * | 2015-11-26 | 2017-06-06 | 国网智能电网研究院 | A kind of flexible ring net controller and control method for electromagnetic looped network solution inscription of loop |
| CN107017635A (en) * | 2017-06-09 | 2017-08-04 | 广东电网有限责任公司电力调度控制中心 | A kind of adaptive islanding control method and system |
| CN110233478A (en) * | 2019-06-06 | 2019-09-13 | 北京四方继保自动化股份有限公司 | Supply network Millisecond method for fast reconstruction and system after electric network fault |
-
2020
- 2020-11-30 CN CN202011377244.3A patent/CN112398135B/en active Active
Patent Citations (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103503269A (en) * | 2011-05-30 | 2014-01-08 | Abb研究有限公司 | System for distributing electric power to an electrical grid |
| CN103427414A (en) * | 2013-06-13 | 2013-12-04 | 国家电网公司 | Parameter design method of symmetrical controllable phase shifter |
| CN203883495U (en) * | 2014-04-15 | 2014-10-15 | 广西电网公司 | Electromagnetic looped network flow monitoring system matched with measure of generator cutting |
| CN104269861A (en) * | 2014-10-13 | 2015-01-07 | 国家电网公司 | Electromagnetic looped network reactive power ring current optimal control method based on flexible looped network controller |
| CN104319765A (en) * | 2014-10-29 | 2015-01-28 | 国家电网公司 | Control method of distributed in-series coupling power flow controller |
| CN106803679A (en) * | 2015-11-26 | 2017-06-06 | 国网智能电网研究院 | A kind of flexible ring net controller and control method for electromagnetic looped network solution inscription of loop |
| CN105958554A (en) * | 2016-04-29 | 2016-09-21 | 贵州电网有限责任公司电力调度控制中心 | Flexible direct current coordination stability control method applied to electromagnetic loop network |
| CN105978135A (en) * | 2016-06-22 | 2016-09-28 | 清华大学 | Current source-type uninterrupted power switch for AC power distribution system |
| CN107017635A (en) * | 2017-06-09 | 2017-08-04 | 广东电网有限责任公司电力调度控制中心 | A kind of adaptive islanding control method and system |
| CN110233478A (en) * | 2019-06-06 | 2019-09-13 | 北京四方继保自动化股份有限公司 | Supply network Millisecond method for fast reconstruction and system after electric network fault |
Non-Patent Citations (1)
| Title |
|---|
| 配电网电磁环网关键技术研究;刘云;李响;李庚银;杨溢;;电器与能效管理技术(第22期);全文 * |
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