Operating mode switching method of series-parallel hybrid distribution transformer and related device

Abstract

The invention provides a working mode switching method of a series-parallel hybrid distribution transformer and a related device. The working mode switching method comprises the following steps: acquiring an electric power parameter; the electric power parameters comprise a current parameter and a voltage parameter; determining a first switching action of the working mode change-over switch based on the current parameter, wherein the first switching action is to switch the working mode from a current and voltage compensation mode to a double-current compensation mode; determining a second switching action of the working mode change-over switch based on the voltage parameter, wherein the second switching action is to switch the working mode from a double-current compensation mode to a current and voltage compensation mode; through the method, smooth switching of the working modes of the series-parallel hybrid distribution transformer can be realized; switching does not depend on control cooperation of a current converter, and the method has the advantages of being simple, reliable and effective.

Description

Technical Field

[0001] The present invention relates to the technical field of distribution networks, and in particular to the technical field of distribution transformers, and specifically to a method for switching working modes of a series-parallel hybrid distribution transformer and related devices. Background Art

[0002] The series-parallel hybrid distribution transformer is a new type of distribution transformer in the distribution network, which consists of a main winding, a back-to-back dual converter, a working mode switching switch, and a control module. The main winding converts the voltage of the medium-voltage distribution network into a low voltage. The back-to-back dual converter consists of a parallel converter and a series converter. The parallel converter performs current compensation for harmonic suppression, three-phase current imbalance compensation, etc., and the series converter performs voltage sag compensation, etc. The working mode switching switch consists of anti-parallel connected thyristor switches. It is used to change the topology of the series-parallel hybrid distribution transformer, and can change the series converter to parallel and the parallel converter to series. The controller is used to control the trigger signals of the back-to-back dual converters and the working mode switching switch.

[0003] There are two types of problems in low-voltage distribution substations, one is current problems such as harmonics, three-phase current imbalance, and insufficient reactive power, and the other is voltage problems such as voltage sag and voltage interruption. Current problems exist all the time, so the management device needs to be connected to the grid at all times; and because it is a current problem, a parallel device needs to be used to inject current to solve it. Voltage problems such as voltage sag and voltage interruption only occur for a short time, so the management device is only put into operation when voltage problems occur; and because it is a voltage problem, a series device needs to be used to compensate for the voltage, which causes the management device used to solve the voltage problem to be idle for a long time. Considering that the management device for current problems and the management device for voltage problems can essentially use power electronic converters, only the control scheme and connection method are different. In the back-to-back dual converters in the series-parallel hybrid distribution transformer, the parallel converter can achieve the management of current problems, the series converter can achieve the management of voltage problems, and the working mode switching switch can change the series converter into a parallel converter, so as to make full use of the series converter when there is no voltage problem and increase the capacity of current compensation; however, the working mode switching switch is composed of thyristor switches, which are semi-controlled devices and can be controlled to be turned on instantly, but will be turned off with delay. Delayed shutdown will lead to uneven working mode switching and cause short circuit problems.

[0004] Therefore, there is a technical problem in the prior art that the working mode switching of the series-parallel hybrid distribution transformer is not smooth and is prone to short circuit. Summary of the invention

[0005] The main purpose of the present invention is to provide a method and related device for switching the working mode of a series-parallel hybrid distribution transformer to solve the technical problem in the prior art that the working mode switching of the series-parallel hybrid distribution transformer is not smooth and easily causes short circuit.

[0006] In order to achieve the above-mentioned purpose, according to one aspect of the present invention, a method for switching the working mode of a series-parallel hybrid distribution transformer is provided, wherein the series-parallel hybrid distribution transformer comprises: a transformer winding, a parallel converter, a series converter, a working mode switching switch, a coupling transformer, a filter and a control device, wherein the working mode switching switch comprises a first switch group, a second switch group, a third switch group, a fourth switch group and a fifth switch group, wherein the first switch group is located between the parallel converter and the transformer winding, the second switch group is located between the parallel converter and the coupling transformer, the third switch group is located between the parallel converter and the coupling transformer, the fourth switch group is located between the series converter and the coupling transformer, and the fifth switch group is located between the coupling transformer and the Between the low-voltage ports, the parallel converter and the series converter are respectively connected to the transformer winding and the coupling transformer through the working mode switching switch; the working mode includes a current-voltage compensation mode and a dual current compensation mode, and the working mode switching method includes the following steps: obtaining power parameters; the power parameters include: current parameters and voltage parameters; based on the current parameters, determining the first switching action of the working mode switching switch, the first switching action is to switch the working mode from the current-voltage compensation mode to the dual current compensation mode; based on the voltage parameters, determining the second switching action of the working mode switching switch, the second switching action is to switch the working mode from the dual current compensation mode to the current-voltage compensation mode.

[0007] In some embodiments, determining the first switching action of the working mode switching switch based on the current parameters includes: determining a current abnormal state based on the current parameters, the current abnormal state at least including harmonics, three-phase current imbalance, and reactive power; based on the current abnormal state, determining the first switching action of the working mode switching switch.

[0008] In some embodiments, determining the first switching action of the working mode switching switch based on the current abnormal state includes: when the current abnormal state is greater than a first preset threshold, performing the first switching action to switch the working mode from the current-voltage compensation mode to the dual current compensation mode; when the current abnormal state is not greater than the first preset threshold, maintaining the working mode as the current-voltage compensation mode.

[0009] In some embodiments, determining the second switching action of the working mode switch based on the voltage parameter includes: determining a voltage sag based on the voltage parameter; and determining the second switching action of the working mode switch based on the voltage sag.

[0010] In some embodiments, the second switching action of determining the operating mode switch based on the voltage sag includes: when the voltage sag is greater than a second preset threshold, performing the second switching action to switch the operating mode from the dual current compensation mode to the current-voltage compensation mode; when the voltage sag is not greater than the second preset threshold, maintaining the operating mode as the dual current compensation mode.

[0011] In some embodiments, performing the second switching action includes: removing the second switch group turn-on signal, delaying for a first preset time, and then turning on the fourth switch group.

[0012] In some implementations, performing the first switching action includes: determining whether the turning on of the second switch group will cause the turning off of the fourth switch group; and determining the first switching action based on the determination result.

[0013] In some embodiments, performing the first switching action includes: determining whether the conduction of each switch in the second switch group will cause the corresponding phase switch in the fourth switch group to be turned off; and determining the first switching action based on the determination result.

[0014] According to another aspect of the present invention, the present invention also provides an operating mode switching device for a series-parallel hybrid distribution transformer, wherein the series-parallel hybrid distribution transformer comprises: a transformer winding, a parallel converter, a series converter, an operating mode switching switch, a coupling transformer, a filter and a control device, wherein the operating mode switching switch comprises a first switch group, a second switch group, a third switch group, a fourth switch group and a fifth switch group, wherein the first switch group is located between the parallel converter and the transformer winding, the second switch group is located between the parallel converter and the coupling transformer, the third switch group is located between the parallel converter and the coupling transformer, the fourth switch group is located between the series converter and the coupling transformer, the fifth switch group is located between the coupling transformer and the low-voltage port, and the parallel converter and a series converter are respectively connected to the transformer winding and the coupling transformer through the working mode switching switch; the working mode includes a current-voltage compensation mode and a dual current compensation mode, and the working mode switching device includes: an acquisition module for acquiring power parameters; the power parameters include: current parameters and voltage parameters; a first determination module for determining a first switching action of the working mode switching switch based on the current parameters, the first switching action is to switch the working mode from the current-voltage compensation mode to the dual current compensation mode; a second determination module for determining a second switching action of the working mode switching switch based on the voltage parameters, the second switching action is to switch the working mode from the dual current compensation mode to the current-voltage compensation mode.

[0015] According to another aspect of the present invention, the present invention further provides a storage medium storing a computer program, wherein the computer program implements the steps of any of the aforementioned methods when executed by a processor.

[0016] According to another aspect of the present invention, the present invention also provides an electronic device, comprising at least a memory and a processor, wherein the memory stores a computer program, and the processor implements the steps of any of the aforementioned methods when executing the computer program on the memory.

[0017] By applying the working mode switching method for a series-parallel hybrid distribution transformer provided by the present invention, a first switching action of the working mode switching switch is determined based on the current parameter, and the first switching action is to switch the working mode from the current-voltage compensation mode to the dual-current compensation mode; a second switching action of the working mode switching switch is determined based on the voltage parameter, and the second switching action is to switch the working mode from the dual-current compensation mode to the current-voltage compensation mode; smooth switching of the working mode of the series-parallel hybrid distribution transformer can be achieved; switching does not need to rely on the control coordination of the converter, and has the characteristics of simplicity, reliability and effectiveness. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The drawings constituting a part of the present application are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0019] Figure 1 It is a circuit diagram of the series-parallel hybrid distribution transformer provided by the present invention;

[0020] Figure 2 It is a flowchart of the steps of the method for switching the working mode of the series-parallel hybrid distribution transformer provided by the present invention;

[0021] Figure 3 is a flowchart of the steps of determining a first switching action of a working mode switching switch based on current parameters provided by the present invention;

[0022] Figure 4 is a schematic diagram of the control flow of the first switching action provided by the present invention;

[0023] Figure 5 is a flowchart of the steps of determining the second switching action of the working mode switching switch based on the voltage parameter provided by the present invention;

[0024] Figure 6 is a schematic diagram of the control flow of the second switching action provided by the present invention;

[0025] Figure 7 is a circuit diagram of the working mode switching provided by the present invention;

[0026] Figure 8 is a simplified circuit diagram of the present invention when the working mode is switched;

[0027] Fig. 9 is an equivalent circuit diagram provided by the present invention;

[0028] Fig.10 The present invention provides , a simulation diagram of the first switching action;

[0029] Fig.11 A and B are provided by the present invention. , a simulation diagram of the first switching action;

[0030] Fig.12 is a simulation diagram of the second switching action provided by the present invention;

[0031] Fig.13 It is a structural block diagram of the working mode switching device of the series-parallel hybrid distribution transformer provided by the present disclosure;

[0032] Fig.14It is a schematic diagram of the structure of the electronic device provided by the present disclosure. DETAILED DESCRIPTION

[0033] The specific embodiments of the present disclosure are described in detail below with reference to the accompanying drawings, but are not intended to limit the present disclosure.

[0034] It should be understood that various modifications may be made to the embodiments disclosed herein. Therefore, the above description should not be considered as limiting, but merely as an example of an embodiment. Other modifications within the scope and spirit of the present disclosure will occur to those skilled in the art.

[0035] The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments of the present disclosure and, together with the general description of the present disclosure given above and the detailed description of the embodiments given below, serve to explain the principles of the present disclosure.

[0036] These and other characteristics of the present disclosure will become apparent from the following description of a preferred form of embodiment given as a non-limiting example, with reference to the attached drawings.

[0037] It should also be understood that, although the present disclosure has been described with reference to some specific examples, those skilled in the art will be able to realize many other equivalent forms of the present disclosure that have the features described in the claims and are therefore within the scope of protection defined thereby.

[0038] The above and other aspects, features and advantages of the present disclosure will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings.

[0039] Specific embodiments of the present disclosure are described hereinafter with reference to the accompanying drawings; however, it should be understood that the disclosed embodiments are merely examples of the present disclosure, which may be implemented in a variety of ways. Well-known and / or repeated functions and structures are not described in detail to avoid obscuring the present disclosure with unnecessary or redundant details. Therefore, the specific structural and functional details disclosed herein are not intended to be limiting, but merely serve as a basis and representative basis for the claims to teach those skilled in the art to use the present disclosure in a variety of ways with substantially any suitable detailed structure.

[0040] It should be noted that the terms "first", "second", etc. in the specification and claims of the present disclosure and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchangeable where appropriate, so that the embodiments of the present disclosure described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, system, product, or device that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products, or devices.

[0041] This specification may use the phrases "in one embodiment," "in another embodiment," "in a further embodiment," or "in other embodiments," all of which may refer to one or more of the same or different embodiments according to the present disclosure.

[0042] The present disclosure is further described below in conjunction with the accompanying drawings and specific embodiments.

[0043] In order to solve the technical problem in the prior art that the working mode switching of a series-parallel hybrid distribution transformer is not smooth and easily causes short circuit, the present invention provides a working mode switching method and related devices for a series-parallel hybrid distribution transformer.

[0044] Figure 1 The structural diagram of the series-parallel hybrid distribution transformer provided by the present invention is shown as follows: Figure 1 As shown, the series-parallel hybrid distribution transformer includes: transformer windings, parallel converters, series converters, working mode switching switches, coupling transformers, filters and control devices.

[0045] Among them, the transformer winding is used for voltage conversion, and the alternating current of the medium voltage power grid is converted into a step-down voltage; the parallel converter is used to inject current into the power grid for current compensation; the series converter compensates the voltage into the power grid through a coupling transformer in the current and voltage compensation mode, and injects current into the power grid for current compensation in the dual current compensation mode; the coupling transformer is used to transfer the electric energy compensated by the parallel converter and the series converter to the distribution network through magnetic circuit coupling, and the parallel converter and the series converter are respectively connected to the transformer winding and the coupling transformer through the working mode switching switch; the working mode includes the current and voltage compensation mode and the dual current compensation mode; the control device is used to control the working mode switching switch according to the received working mode so that the parallel converter and the series converter perform corresponding electric energy compensation.

[0046] In order to switch the working mode, the working mode switching switch includes a first switch group, a second switch group, a third switch group, a fourth switch group, a fifth switch group and a sixth switch group, wherein the first switch group is located between the parallel converter and the transformer winding, the second switch group is located between the parallel converter and the coupling transformer, the third switch group is located between the parallel converter and the coupling transformer, the fourth switch group is located between the series converter and the coupling transformer, and the fifth switch group is located between the coupling transformer and the low-voltage port; the first switch group, the second switch group, the third switch group, the fourth switch group and the fifth switch group are all composed of three phase switches ABC, for example, the first switch group includes a first A phase switch, a first B phase switch and a first C phase switch; the sixth switch group consists of two switches.

[0047] In the process of switching the working mode, the conduction states of the second switch group, the fourth switch group and the fifth switch group need to be changed, as shown in Table 1.

[0048] Table 1 Schematic diagram of working mode switching switch

[0049]

[0050] Figure 2 A flow chart of the steps of the method for switching the working mode of the series-parallel hybrid distribution transformer provided by the present invention is shown. As shown in FIG2 , the method for switching the working mode of the series-parallel hybrid distribution transformer comprises the following steps:

[0051] S101, acquiring power parameters; the power parameters include: current parameters and voltage parameters.

[0052] In this step, power parameters are obtained; the power parameters include: current parameters and voltage parameters.

[0053] Specifically, the power parameters such as the actual voltage and actual current outputted by the distribution network in real time are collected, and the working mode is determined according to the actual voltage and the actual current. Among them, a current transformer can be used to detect the current in the A, B, C items and the grounding wire in the distribution network, and a voltage transformer can be used to detect the voltage of the A, B, C items in the distribution network.

[0054] For example, the A-phase current of the distribution network can be detected by the first current transformer, the B-phase current of the distribution network can be detected by the second current transformer, the C-phase current of the distribution network can be detected by the third current transformer, the ground current of the distribution network can be detected by the fourth current transformer, the A-phase voltage of the distribution network can be detected by the first voltage transformer, the B-phase voltage of the distribution network can be detected by the second voltage transformer, and the C-phase voltage of the distribution network can be detected by the third voltage transformer.

[0055] S102, determining a first switching action of the working mode switch based on the current parameter, wherein the first switching action is to switch the working mode from a current-voltage compensation mode to a dual-current compensation mode.

[0056] After completing the above step S101, in this step, a first switching action of the working mode switching switch is determined based on the current parameter.

[0057] Specifically, the series-parallel hybrid distribution transformer has two working modes, a current-voltage compensation mode and a dual-current compensation mode. After the device is started, it enters the current-voltage compensation mode, and then determines whether the working mode switching switch performs the first switching action based on the current parameter.

[0058] Further, Figure 3 A flowchart of the steps of determining the first switching action of the working mode switching switch based on the current parameter provided by the present invention is shown. As shown in the figure, the first switching action of determining the working mode switching switch based on the current parameter includes the following steps:

[0059] S201, determining a current abnormal state based on the current parameters, wherein the current abnormal state at least includes harmonics, three-phase current imbalance, and reactive power.

[0060] In this step, the abnormal current state is determined based on the current parameters, and the abnormal current state at least includes harmonics, three-phase current imbalance, and reactive power.

[0061] Specifically, after obtaining the current parameters, the abnormal current state is determined based on various current values ​​of the distribution network, for example, the balance state of the three-phase current is judged, and whether there are harmonics and reactive power is judged.

[0062] S202: Determine a first switching action of the working mode switching switch based on the abnormal current state.

[0063] After completing the above step S201, in this step, based on the abnormal current state, a first switching action of the working mode switching switch is determined.

[0064] Specifically, when the current abnormal state is greater than the first preset threshold value, it means that the current problem is more serious at this time and the current needs to be compensated. The first switching action is performed to switch the working mode from the current and voltage compensation mode to the dual current compensation mode; when the current abnormal state is not greater than the first preset threshold value, it means that the current problem in the power grid is not serious at this time, and the working mode is maintained at the current and voltage compensation mode.

[0065] The first preset threshold value may be set according to the operating status of the distribution network or according to the experience of the operator.

[0066] Since the working mode switching switch is composed of anti-parallel thyristors, it has the characteristics of instantaneous conduction and delayed shutdown. In the series-parallel hybrid distribution transformer, the conduction of one part of the switch will cause the shutdown of the other part of the switch. Figure 4 The control flow diagram of the first switching action in this patent is shown as follows: Figure 4 As shown, when performing the first switching action, first, it is necessary to determine whether the conduction of the second switch group will cause the fourth switch group to be turned off, and determine the first switching action based on the judgment result, wherein when the conduction of the second switch group will cause the fourth switch group to be turned off, the second switch group is turned on.

[0067] Specifically, since each switch group includes three switches, during the judgment process, it is judged whether the conduction of each switch in the second switch group will cause the corresponding phase switch in the fourth switch group to be turned off, and the first switching action is determined based on the judgment result. Among them, the first switching action includes switching the three-phase switches A, B, and C respectively, that is, when the conduction of the A-phase switch in the second switch group will cause the A-phase switch in the fourth switch group to be turned off, the A-phase switch in the second switch group is turned on; when the B-phase switch and the C-phase switch of the second switch group meet the above requirements, the corresponding conduction operation is performed.

[0068] S103, determining a second switching action of the working mode switch based on the voltage parameter, wherein the second switching action is to switch the working mode from the dual current compensation mode to the current-voltage compensation mode.

[0069] After completing the above steps, in this step, a second switching action of the working mode switch is determined based on the voltage parameter, and the second switching action is to switch the working mode from the dual current compensation mode to the current-voltage compensation mode.

[0070] Specifically, after completing the first switching action, the device is in a dual current compensation mode. At this time, the second switching action of the working mode switching switch is determined based on the voltage parameter. The second switching action is to switch the working mode from the dual current compensation mode to the current-voltage compensation mode. That is, in this step, the timing of switching the working mode back to the current-voltage compensation mode is determined based on the voltage parameter.

[0071] Further, Figure 5 A flow chart showing the steps of determining the second switching action of the working mode switching switch based on the voltage parameter is shown, Figure 5As shown, determining the second switching action of the working mode switching switch based on the voltage parameter includes the following steps:

[0072] S301, determining a voltage sag based on the voltage parameter.

[0073] In this step, the voltage sag is determined based on the voltage parameter.

[0074] Specifically, a voltage sag is used to characterize a voltage problem during the operation of a power grid. When the voltage sag is large, voltage compensation needs to be provided to the power grid.

[0075] S302: Determine a second switching action of the working mode switch based on the voltage sag.

[0076] After completing the above step S301, in this step, a second switching action of the working mode switch is determined based on the voltage sag.

[0077] Specifically, when the voltage sag is greater than a second preset threshold, the second switching action is performed to switch the working mode from the dual current compensation mode to the current-voltage compensation mode; when the voltage sag is not greater than the second preset threshold, the working mode is maintained as the dual current compensation mode.

[0078] The second preset threshold value may be set according to the operating status of the distribution network or according to the experience of the operator.

[0079] Figure 6 A control flow diagram of the second switching action in the present invention is shown. As shown in the figure, when performing the second switching action, the second switch group conduction signal is first removed, and after a delay of the first preset time, the fourth switch group is turned on; wherein the first preset time can be, for example, 2ms.

[0080] In a specific embodiment, by measuring the three-phase voltage u of the main winding of the series-parallel hybrid distribution transformer sabc , the phase ωt is obtained through the phase-locked loop, and the range of ωt is judged to control the corresponding A-phase, B-phase, and C-phase working mode switching switches to be turned on, thereby completing the grid commutation and realizing rapid switching of the working mode.

[0081] In order to achieve the rapid reduction of the current of the working mode switching switch to zero and achieve the fast switching of the working mode switching, in the first switching action, the current of the fourth switch group in the working mode switching switch is rapidly reduced to zero by turning on the second switch group in the working mode switching switch at a specific time. In the second switching action, the current of the second switch group in the working mode switching switch is rapidly reduced to zero by turning on the fourth switch group in the working mode switching switch at a specific time.

[0082] Figure 7 The circuit diagram of the present invention when the working mode is switched is shown in FIG. Figure 7 As shown, since the switching action is a transient process, the capacitor voltage is set to remain unchanged during the transient process. At the same time, the converter side inductance L of the LCL in the filter is taken into account. 21 The current does not change, so the simplified circuit diagram is as follows Figure 8 shown.

[0083] Among them, the voltage at the outlet of the secondary winding of the main winding of the series-parallel hybrid distribution transformer is:

[0084]

[0085] In the formula, u sa 、u sb 、u sc They are the A-phase voltage, B-phase voltage, and C-phase voltage of the main winding and secondary winding of the series-parallel hybrid distribution transformer. N It is the rated effective value of phase voltage of the power distribution system.

[0086] The load can be equivalent to Z L , the load impedance angle is The load current is then:

[0087]

[0088] In the formula, i La 、i Lb 、i Lc They are respectively the A phase load current, the B phase load current, and the C phase load current; U N is the rated voltage effective value.

[0089] After receiving the working mode switching instruction, the current in the fourth switch group in the working mode switching switch cannot change suddenly. The fifth switch group in the working mode switching switch is directly turned on. Combining the current relationship between the primary and secondary sides of the coupling transformer T, it can be known that the current flowing through the fourth switch group of the working mode switching switch is:

[0090]

[0091] Where N is the autotransformer ratio of the hybrid distribution transformer; Ni La 、Ni Lb 、Ni Lc The A-phase current, B-phase current, and C-phase current flowing through the working mode switching switch S4.

[0092] If the second switch group is turned on, the voltage across the fourth switch group becomes the voltage at the outlet of the secondary winding of the main winding of the series-parallel hybrid distribution transformer.

[0093] In order to make the voltage and current phases of the fourth switch group in the working mode switching switch opposite, the following conditions must be met within a phase-locked cycle to form a shutdown condition:

[0094]

[0095] Solving the above equation, we get the following result:

[0096] After the A-phase switch of the second switch group is turned on, the period during which the A-phase switch of the fourth switch group is quickly turned off is:

[0097]

[0098] After the B-phase switch of the second switch group is turned on, the period during which the B-phase switch of the fourth switch group is quickly turned off is:

[0099]

[0100] After the C-phase switch of the second switch group is turned on, the period during which the C-phase switch of the fourth switch group is quickly turned off is:

[0101]

[0102] It can be seen from this that when In one power frequency cycle, when the phase ωt of the phase-locked loop output satisfies (k = 1, 2, 3, 4, 5 and ), the three-phase switches in the second switch group can use the same conduction signal to complete grid commutation, ensuring rapid switching of the working mode.

[0103] When When , only two phases meet the simultaneous shutdown condition, and the other phase does not meet it, so the turn-on signal is that the two phases are turned on first, and the other phase is turned on later. Assume that A and B phases are turned on at the same time, and C phase is turned on later. The equivalent circuit at this time is as follows Fig. 9 As shown, since the inductor current remains unchanged, that is, i L2a 、i L2b 、i L2c unchanged, so at this time we have

[0104]

[0105] Among them, i 2a 、i 2b The current flows through the second A-phase switch and the second B-phase switch of the working mode switching switch. That is, the A-phase and B-phase currents Ni L2a 、Ni L2bThe current flows through the second A-phase switch and the second B-phase switch of the working mode switching switch and quickly passes through 0. The C-phase passes through the neutral point of the coupling transformer and flows to the A-phase and B-phase, so that the current quickly passes through 0.

[0106] In order to verify the above results, the load impedance angle is set to hour, The system simulation is performed at the same time, and the simulation results are as follows Fig.10 , Fig.11 As shown, from Fig.10 It can be seen that the signal for the first switching action is received at 1.495s; when the load impedance angle is 0°, the phase switches in the second switch group use the same trigger signal to complete the grid commutation, so that the current in the fourth switch group quickly drops to 0.

[0107] When the load impedance angle is 70°, if the same trigger signal is used, then Fig.11 As shown in A, a large short-circuit current is generated, causing damage to the equipment; Fig.11 As shown in B, according to the phase-locked loop angle range judgment, the grid commutation can be achieved through the coordination of the trigger signal, and the current in the fourth switch group quickly drops to 0.

[0108] When the second switching is performed, due to reactive power compensation before switching, the currents of the second A-phase switch, the second B-phase switch, and the second C-phase switch of the working mode switching switch that need to be turned off are:

[0109]

[0110] When a voltage sag occurs, the voltage u of the secondary winding of the main winding of the series-parallel hybrid distribution transformer is sa 、u sb 、u sc Reduced, so that:

[0111]

[0112] Because u sa 、u sb 、u sc The capacitor voltage u decreases ca 、u cb 、u cc unchanged, thus causing the differential product term to increase, resulting in the grid-side inductance L 22 The smaller the value, the faster the current change rate increases, which can cause the current to quickly pass through zero and realize grid commutation.

[0113] In order to utilize the grid commutation caused by voltage sag without introducing new current branches, it is necessary to delay turning on the fourth switch group of the working mode switching switch so that the second switch group of the working mode switching switch is quickly turned off.

[0114] Fig.12 FIG. 4 shows a schematic diagram of the switching current for simulating and verifying the above results. Fig.12 As shown in A, at 1.495s, a voltage sag occurs, and the second switching action signal is received, and the trigger signal of the second switch group of the working mode switching switch is removed. At this time, if the fourth switch group in the working mode switching switch is directly turned on, a short circuit will be caused, and the rapid switching of the working mode cannot be completed. Fig.12 It can be seen from B that after the second switch group is turned off, the fourth switch group of the working mode switching switch is turned on, and the current passing through the fourth switch group quickly becomes 0.

[0115] By applying the working mode switching method for a series-parallel hybrid distribution transformer provided by the present invention, a first switching action of the working mode switching switch is determined based on the current parameter, and the first switching action is to switch the working mode from the current-voltage compensation mode to the dual-current compensation mode; a second switching action of the working mode switching switch is determined based on the voltage parameter, and the second switching action is to switch the working mode from the dual-current compensation mode to the current-voltage compensation mode; smooth switching of the working mode of the series-parallel hybrid distribution transformer can be achieved; switching does not need to rely on the control coordination of the converter, and has the characteristics of simplicity, reliability and effectiveness.

[0116] In order to better implement the above method, the second aspect of the present disclosure further provides an operating mode switching device for a series-parallel hybrid distribution transformer, and the operating mode switching device can be integrated on an electronic device.

[0117] For example, Fig.13 As shown, the switching device 200 may include: an acquisition module 210, a first determination module 220 and a second determination module 230, which are specifically as follows:

[0118] An acquisition module 210, the acquisition module is used to acquire power parameters; the power parameters include: current parameters and voltage parameters;

[0119] A first determining module 220, the first determining module 220 is used to determine a first switching action of the working mode switch based on the current parameter, the first switching action is to switch the working mode from the current-voltage compensation mode to the dual-current compensation mode;

[0120] The second determination module 230 is used to determine a second switching action of the working mode switch based on the voltage parameter, and the second switching action is to switch the working mode from the dual current compensation mode to the current-voltage compensation mode.

[0121] Furthermore, the first determination module 220 includes a first determination unit and a second determination unit, wherein the first determination unit is used to determine the current abnormal state based on the current parameters, and the current abnormal state at least includes harmonics, three-phase current imbalance, and reactive power; the second determination unit is used to determine the first switching action of the working mode switching switch based on the current abnormal state.

[0122] Further, the second determination module 230 includes a third determination unit and a fourth determination unit, wherein the third determination unit is used to determine the voltage sag based on the voltage parameter; and the fourth determination unit is used to determine the second switching action of the working mode switch based on the voltage sag.

[0123] By using the working mode switching device for the series-parallel hybrid distribution transformer provided by the present invention, a first switching action of the working mode switching switch is determined based on the current parameter, and the first switching action is to switch the working mode from the current-voltage compensation mode to the dual-current compensation mode; a second switching action of the working mode switching switch is determined based on the voltage parameter, and the second switching action is to switch the working mode from the dual-current compensation mode to the current-voltage compensation mode; the smooth switching of the working mode of the series-parallel hybrid distribution transformer can be achieved; the switching does not need to rely on the control coordination of the converter, and has the characteristics of simplicity, reliability and effectiveness.

[0124] A person of ordinary skill in the art will appreciate that all or part of the steps in the various methods of the above embodiments may be completed by instructions, or by controlling related hardware through instructions. The instructions may be stored in a computer-readable storage medium and loaded and executed by a processor.

[0125] To this end, a third embodiment of the present disclosure provides a storage medium, which is a computer-readable medium and stores a computer program. When the computer program is executed by a processor, the method provided by the embodiment of the present disclosure is implemented, including the following steps S11 to S13:

[0126] S11, acquiring power parameters; the power parameters include: current parameters and voltage parameters;

[0127] S12, determining a first switching action of the working mode switch based on the current parameter, wherein the first switching action is to switch the working mode from the current-voltage compensation mode to the dual-current compensation mode;

[0128] S13, determining a second switching action of the working mode switch based on the voltage parameter, wherein the second switching action is to switch the working mode from the dual current compensation mode to the current-voltage compensation mode.

[0129] Furthermore, when the computer program is executed by a processor, other methods provided by any of the above embodiments of the present disclosure are implemented.

[0130] By applying the working mode switching method for a series-parallel hybrid distribution transformer provided by the present invention, a first switching action of the working mode switching switch is determined based on the current parameter, and the first switching action is to switch the working mode from the current-voltage compensation mode to the dual-current compensation mode; a second switching action of the working mode switching switch is determined based on the voltage parameter, and the second switching action is to switch the working mode from the dual-current compensation mode to the current-voltage compensation mode; smooth switching of the working mode of the series-parallel hybrid distribution transformer can be achieved; switching does not need to rely on the control coordination of the converter, and has the characteristics of simplicity, reliability and effectiveness.

[0131] A fourth embodiment of the present disclosure provides an electronic device, such as Fig.14 As shown, the electronic device at least includes a memory 310 and a processor 320. The memory 310 stores a computer program. The processor 320 implements the method provided by any embodiment of the present disclosure when executing the computer program on the memory 310. Exemplarily, the method executed by the electronic device computer program is as follows:

[0132] S21, acquiring power parameters; the power parameters include: current parameters and voltage parameters;

[0133] S22, determining a first switching action of the working mode switch based on the current parameter, wherein the first switching action is to switch the working mode from the current-voltage compensation mode to the dual-current compensation mode;

[0134] S23, determining a second switching action of the working mode switch based on the voltage parameter, wherein the second switching action is to switch the working mode from the dual current compensation mode to the current-voltage compensation mode.

[0135] In a specific implementation, the acquisition module 210, the first determination module 220 and the second determination module 230 are all stored in the memory as program units, and the processor executes the program units stored in the memory to implement corresponding functions.

[0136] By applying the working mode switching method for a series-parallel hybrid distribution transformer provided by the present invention, a first switching action of the working mode switching switch is determined based on the current parameter, and the first switching action is to switch the working mode from the current-voltage compensation mode to the dual-current compensation mode; a second switching action of the working mode switching switch is determined based on the voltage parameter, and the second switching action is to switch the working mode from the dual-current compensation mode to the current-voltage compensation mode; smooth switching of the working mode of the series-parallel hybrid distribution transformer can be achieved; switching does not need to rely on the control coordination of the converter, and has the characteristics of simplicity, reliability and effectiveness.

[0137] The storage medium may be included in the electronic device, or may exist independently without being installed in the electronic device.

[0138] The storage medium carries one or more programs. When the one or more programs are executed by the electronic device, the electronic device: obtains at least two Internet Protocol addresses; sends a node evaluation request including at least two Internet Protocol addresses to a node evaluation device, wherein the node evaluation device selects an Internet Protocol address from the at least two Internet Protocol addresses and returns it; receives the Internet Protocol address returned by the node evaluation device; wherein the obtained Internet Protocol address indicates an edge node in a content distribution network.

[0139] Alternatively, the storage medium carries one or more programs, and when the one or more programs are executed by the electronic device, the electronic device: receives a node evaluation request including at least two Internet Protocol addresses; selects an Internet Protocol address from the at least two Internet Protocol addresses; and returns the selected Internet Protocol address; wherein the received Internet Protocol address indicates an edge node in a content distribution network.

[0140] Computer program code for performing operations of the present disclosure may be written in one or more programming languages, or a combination thereof, including, but not limited to, object-oriented programming languages, such as Java, Smalltalk, C++, and conventional procedural programming languages, such as "C" or similar programming languages. The program code may be executed entirely on the passenger computer, partially on the passenger computer, as a separate software package, partially on the passenger computer and partially on a remote computer, or entirely on a remote computer or server. In cases involving a remote computer, the remote computer may be connected to the passenger computer via any type of network, including a local area network (LAN) or a wide area network (WAN), or may be connected to an external computer (e.g., via the Internet using an Internet service provider).

[0141] It should be noted that the storage medium disclosed above may be a computer-readable signal medium or a computer-readable storage medium or any combination of the above two. The computer-readable storage medium may be, for example, but not limited to, an electrical, magnetic, optical, electromagnetic, infrared, or semiconductor system, device or device, or any combination of the above. More specific examples of computer-readable storage media may include, but are not limited to: an electrical connection with one or more wires, a portable computer disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disk read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the above. In the present disclosure, a computer-readable storage medium may be any tangible medium containing or storing a program that may be used by or in combination with an instruction execution system, device or device. In the present disclosure, a computer-readable signal medium may include a data signal propagated in a baseband or as part of a carrier wave, in which a computer-readable program code is carried. This propagated data signal may take a variety of forms, including but not limited to an electromagnetic signal, an optical signal, or any suitable combination of the above. The computer readable signal medium may also be any storage medium other than a computer readable storage medium, which may send, propagate or transmit a program for use by or in conjunction with an instruction execution system, apparatus or device. The program code contained on the storage medium may be transmitted using any suitable medium, including but not limited to: wires, optical cables, RF (radio frequency), etc., or any suitable combination of the above.

[0142] The flow chart and block diagram in the accompanying drawings illustrate the possible architecture, function and operation of the system, method and computer program product according to various embodiments of the present disclosure. In this regard, each square box in the flow chart or block diagram can represent a module, a program segment or a part of a code, and the module, the program segment or a part of the code contains one or more executable instructions for realizing the specified logical function. It should also be noted that in some implementations as replacements, the functions marked in the square box can also occur in a sequence different from that marked in the accompanying drawings. For example, two square boxes represented in succession can actually be executed substantially in parallel, and they can sometimes be executed in the opposite order, depending on the functions involved. It should also be noted that each square box in the block diagram and / or flow chart, and the combination of the square boxes in the block diagram and / or flow chart can be implemented with a dedicated hardware-based system that performs a specified function or operation, or can be implemented with a combination of dedicated hardware and computer instructions.

[0143] The units involved in the embodiments described in the present disclosure may be implemented by software or hardware, wherein the name of a unit does not, in some cases, constitute a limitation on the unit itself.

[0144] The functions described above herein may be performed at least in part by one or more hardware logic components. For example, without limitation, exemplary types of hardware logic components that may be used include: field programmable gate arrays (FPGAs), application specific integrated circuits (ASICs), application specific standard products (ASSPs), systems on chips (SOCs), complex programmable logic devices (CPLDs), and the like.

[0145] In the context of the present disclosure, a machine-readable medium may be a tangible medium that may contain or store a program for use by or in conjunction with an instruction execution system, device, or equipment. A machine-readable medium may be a machine-readable signal medium or a machine-readable storage medium. A machine-readable medium may include, but is not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, device, or equipment, or any suitable combination of the foregoing. A more specific example of a machine-readable storage medium may include an electrical connection based on one or more lines, a portable computer disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disk read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing.

[0146] The above description is only a preferred embodiment of the present disclosure and an explanation of the technical principles used. Those skilled in the art should understand that the scope of disclosure involved in the present disclosure is not limited to the technical solutions formed by a specific combination of the above technical features, but should also cover other technical solutions formed by any combination of the above technical features or their equivalent features without departing from the above disclosed concept. For example, the above features are replaced with the technical features with similar functions disclosed in the present disclosure (but not limited to) by each other to form a technical solution.

[0147] In addition, although each operation is described in a specific order, this should not be understood as requiring these operations to be performed in the specific order shown or in a sequential order. Under certain circumstances, multitasking and parallel processing may be advantageous. Similarly, although some specific implementation details are included in the above discussion, these should not be interpreted as limiting the scope of the present disclosure. Some features described in the context of a separate embodiment can also be implemented in a single embodiment in combination. On the contrary, the various features described in the context of a single embodiment can also be implemented in multiple embodiments individually or in any suitable sub-combination mode.

[0148] Although the subject matter has been described in language specific to structural features and / or methodological logical actions, it should be understood that the subject matter defined in the appended claims is not necessarily limited to the specific features or actions described above. On the contrary, the specific features and actions described above are merely example forms of implementing the claims.

[0149] Multiple embodiments of the present disclosure are described in detail above, but the present disclosure is not limited to these specific embodiments. Those skilled in the art can make various variations and modifications to the embodiments based on the concepts of the present disclosure, and these variations and modifications should all fall within the scope of protection required by the present disclosure.

Claims

1. A method for switching the working mode of a series-parallel hybrid distribution transformer, characterized in that: The series-parallel hybrid distribution transformer comprises: a transformer winding, a parallel converter, a series converter, a working mode switching switch, a coupling transformer, a filter and a control device, wherein the working mode switching switch comprises a first switch group, a second switch group, a third switch group, a fourth switch group and a fifth switch group, wherein the first switch group is located between the parallel converter and the transformer winding, the second switch group is located between the parallel converter and the coupling transformer, the third switch group is located between the parallel converter and the coupling transformer, the fourth switch group is located between the series converter and the coupling transformer, and the fifth switch group is located between the coupling transformer and the low-voltage port, and the parallel converter and the series converter are respectively connected to the transformer winding and the coupling transformer through the working mode switching switch; the working modes include a current-voltage compensation mode and a dual current compensation mode, and the working mode switching method comprises the following steps: Acquiring power parameters; the power parameters include: current parameters and voltage parameters; Determining a first switching action of the working mode switch based on the current parameter, wherein the first switching action is to switch the working mode from the current-voltage compensation mode to the dual-current compensation mode; A second switching action of the working mode switch is determined based on the voltage parameter, wherein the second switching action is to switch the working mode from the dual current compensation mode to the current-voltage compensation mode.

2. The method for switching the working mode of the series-parallel hybrid distribution transformer according to claim 1, characterized in that: The determining the first switching action of the working mode switching switch based on the current parameter includes: Determine a current abnormal state based on the current parameters, wherein the current abnormal state includes at least harmonics, three-phase current imbalance, and reactive power; Based on the abnormal current state, a first switching action of the working mode switching switch is determined.

3. The method for switching the working mode of the series-parallel hybrid distribution transformer according to claim 2, characterized in that: The determining, based on the abnormal current state, a first switching action of the working mode switching switch comprises: When the abnormal current state is greater than a first preset threshold, performing the first switching action to switch the working mode from the current-voltage compensation mode to the dual-current compensation mode; When the abnormal current state is not greater than a first preset threshold, the operating mode is maintained as a current and voltage compensation mode.

4. The method for switching the working mode of the series-parallel hybrid distribution transformer according to claim 1, characterized in that: The determining the second switching action of the working mode switching switch based on the voltage parameter includes: determining a voltage sag based on the voltage parameter; A second switching action of the working mode switch is determined based on the voltage sag.

5. The method for switching the working mode of the series-parallel hybrid distribution transformer according to claim 4, characterized in that: The determining of the second switching action of the working mode switch based on the voltage sag comprises: When the voltage sag is greater than a second preset threshold, performing the second switching action to switch the working mode from the dual current compensation mode to the current and voltage compensation mode; When the voltage sag is not greater than a second preset threshold, the operating mode is maintained as the dual current compensation mode.

6. The method for switching the working mode of the series-parallel hybrid distribution transformer according to claim 5, characterized in that: The performing of the second switching action includes: removing the second switch group conduction signal, delaying for a first preset time, and then conducting the fourth switch group.

7. The method for switching the working mode of the series-parallel hybrid distribution transformer according to claim 3, characterized in that: Performing the first switching action includes: Determining whether the conduction of the second switch group will cause the fourth switch group to be turned off; The first switching action is determined based on the determination result.

8. The method for switching the working mode of the series-parallel hybrid distribution transformer according to claim 7, characterized in that: Performing the first switching action includes: Determine whether the conduction of each switch in the second switch group will cause the corresponding phase switch in the fourth switch group to be turned off; The first switching action is determined based on the determination result.

9. A device for switching the working mode of a series-parallel hybrid distribution transformer, characterized in that: The series-parallel hybrid distribution transformer comprises: a transformer winding, a parallel converter, a series converter, a working mode switching switch, a coupling transformer, a filter and a control device, wherein the working mode switching switch comprises a first switch group, a second switch group, a third switch group, a fourth switch group and a fifth switch group, wherein the first switch group is located between the parallel converter and the transformer winding, the second switch group is located between the parallel converter and the coupling transformer, the third switch group is located between the parallel converter and the coupling transformer, the fourth switch group is located between the series converter and the coupling transformer, and the fifth switch group is located between the coupling transformer and the low-voltage port, and the parallel converter and the series converter are respectively connected to the transformer winding and the coupling transformer through the working mode switching switch; the working modes include a current-voltage compensation mode and a dual current compensation mode, and the working mode switching device comprises: An acquisition module, used for acquiring power parameters; the power parameters include: current parameters and voltage parameters; A first determining module, configured to determine a first switching action of the working mode switch based on the current parameter, wherein the first switching action is to switch the working mode from a current-voltage compensation mode to a dual-current compensation mode; The second determination module is used to determine a second switching action of the working mode switch based on the voltage parameter, and the second switching action is to switch the working mode from the dual current compensation mode to the current-voltage compensation mode.

10. A storage medium storing a computer program, characterized in that: When the computer program is executed by a processor, the steps of the method for switching the working mode of the series-parallel hybrid distribution transformer according to any one of claims 1 to 8 are implemented.

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