A non-arc on-load automatic voltage regulating distribution transformer device and voltage regulating method thereof

Abstract

The present invention provides an arc-free on-load automatic voltage-regulating distribution transformer device, which includes: a low-voltage side and a high-voltage side; the low-voltage side includes: a low-voltage winding, and the high-voltage side includes: N voltage-regulating windings, N switch modules, a high-voltage winding and a voltage-regulating control module, each voltage-regulating winding is connected in parallel with each switch module; the high-voltage winding and the N switch modules are connected in series. The technical solution provided by the present invention utilizes the vector series connection of the voltage-regulating winding and the transition function of the electronic switch unit, which eliminates the generation of arcs during the voltage regulation process on the one hand, and improves the speed, range and accuracy of the voltage regulation on the other hand.

Description

Technical Field

[0001] The invention relates to the technical field of automatic voltage regulation of distribution transformers, and in particular to an arc-free on-load automatic voltage regulation distribution transformer device and a voltage regulation method thereof. Background Art

[0002] The application of on-load voltage-changing transformers in power systems is becoming more and more widespread, and it plays a vital role in improving the system voltage quality and power supply reliability. However, the traditional on-load voltage-changing transformer is completed by adjusting its tap and related electric components by a mechanical on-load tap changer. When the tap changer switches with load, a large arc is generated, which is easy to burn the contacts and cause oil pollution, affecting the insulation characteristics and service life of the transformer. The electric operating mechanism is prone to failure. According to relevant statistics, its failure rate accounts for about 80% of the failures of the tap changer. The maintenance workload is large, which restricts the on-load voltage-changing function of the transformer.

[0003] There are currently two problems with the automatic voltage regulation technology of distribution transformers: First, when the reactive power of the power system is sufficient, the most effective way to stabilize the voltage is to use on-load automatic voltage regulation for distribution transformers. The on-load voltage-regulating tap changer is the main device of the automatic voltage-regulating transformer. Most of the existing tap changers are mechanical contact switches. This type of switch not only generates arcs when switching, but also the mechanical contacts are easily damaged. In addition, the adjustment speed is slow and cannot be operated frequently, thus limiting the application scope of this type of switch. Second, the adjustment accuracy of conventional distribution transformers with winding tap adjustment is not high, which is about 2.5% of the given voltage. In the case of positive and negative three-level winding taps, the adjustment range of the distribution transformer is about -7.5% to 7.5% of its given voltage.

[0004] At present, there are also a small number of patents related to using power electronic device switch modules to control the transformer voltage regulating winding to achieve voltage regulation. However, these patents have complex topological structures and are difficult to implement. On the other hand, the power electronic devices are always in working state under normal conditions, resulting in energy loss, continuous driving and poor anti-disturbance capabilities.

[0005] Therefore, it is necessary to provide a technical solution to meet the needs of the prior art. Summary of the invention

[0006] In order to overcome the deficiencies of the above-mentioned prior art, the present invention provides an arc-free on-load automatic voltage-regulating distribution transformer device, which includes: a low-voltage side and a high-voltage side; the low-voltage side includes a low-voltage winding, and the high-voltage side includes: N voltage-regulating windings, N switch modules, high-voltage windings and a voltage-regulating control module, each voltage-regulating winding is connected in parallel with each switch module; the high-voltage winding and the N switch modules are connected in series. The switch module includes: a switching switch, an electronic switch unit and a normally closed switch.

[0007] The diverter switch includes: a magnetic latching relay or a position diverter switch with four terminals.

[0008] One end of the two terminals of a position switch in the position switch is connected to one end of the voltage regulating winding, and the other two terminals are respectively connected to two terminals in the switch module connected in series to the outside;

[0009] Two terminals of another position switch in the position switch are connected to the other end of the voltage regulating winding, and its other two terminals are respectively connected to the two terminals of the switch module connected in series to the outside; the two ends of the electronic switch unit and the normally closed switch are respectively connected to the two terminals of the switch module connected in series to the outside.

[0010] The external connection end of the electronic switch unit is connected to the two ends of the varistor; the varistor is connected in parallel with two thyristors connected in reverse order.

[0011] One external connection end of the electronic switch unit is respectively connected to the cathode of the diode and the collector of the insulated gate bipolar transistor; the other external connection end of the electronic switch unit is respectively connected to the cathode of another diode and the collector of another insulated gate bipolar transistor; the anodes of the two diodes are respectively connected to the emitters of the two insulated gate bipolar transistors; the anode of the diode is connected to the anode of another diode, and the emitter of the insulated gate bipolar transistor is connected to the emitter of another insulated gate bipolar transistor.

[0012] One external connection end of the electronic switch unit is respectively connected to the cathode of the diode and the emitter of the insulated gate bipolar transistor; the other external connection end of the electronic switch unit is respectively connected to the cathode of another diode and the emitter of another insulated gate bipolar transistor; the anodes of the two diodes are respectively connected to the collectors of the two insulated gate bipolar transistors; the anode of the diode is connected to the anode of another diode, and the collector of the insulated gate bipolar transistor is connected to the collector of another insulated gate bipolar transistor.

[0013] Two parallel diode branches are provided between the two external connection ends of the electronic switch unit; one diode branch is provided with two diodes with cathodes connected in reverse, and the other diode branch is provided with two diodes with anodes connected in reverse; the cathodes of the two diodes with cathodes connected in reverse are respectively connected to the collectors of the insulated gate bipolar transistors, and the anodes of the two diodes with anodes connected in reverse are respectively connected to the emitters of the insulated gate bipolar transistors.

[0014] The voltage regulation control module comprises: a power taking unit, an operation control unit connected to the power taking unit, and a measuring unit and a trigger output unit connected to the operation control unit.

[0015] The method comprises the following steps:

[0016] A. Determine the difference between the current output voltage of the low voltage side and the given voltage;

[0017] B. Compare the difference with the voltage regulation step size on the low-pressure side;

[0018] C. Form the control logic of the switch module according to the change of each bit of the high-voltage side voltage regulating winding state matrix;

[0019] D. According to the control logic of all switch modules, adjust the series connection status of the voltage regulating winding in turn.

[0020] Step B includes:

[0021] B1. If the difference is less than the voltage adjustment step, return to continue to determine the size of the difference;

[0022] B2. If the difference is greater than the voltage regulation step, determine that the state matrix corresponding to the current high-voltage side voltage regulation winding is S.

[0023] Step B2 includes:

[0024] When the current low-voltage side voltage is adjusted to a given voltage, the state matrix corresponding to the high-voltage side voltage regulating winding is S'.

[0025] Step C includes:

[0026] C1. Determine whether the first state quantity of the state matrix S and S' has changed;

[0027] C2. If the first state quantity changes, the control logic of the switch module corresponding to the state bit is formed according to the change of the first state quantity;

[0028] C3. If the first state quantity does not change, continue to determine whether the second state quantity of the state matrix S and S' has changed;

[0029] C4. If the second bit state quantity changes, the control logic of the switch module corresponding to the state bit is formed according to the change of the second bit state;

[0030] C5. If the state of the second bit does not change, continue to judge the next bit until the last bit.

[0031] Step D includes:

[0032] D1. According to the control logic of the switch module, control the actions of all switch modules in sequence;

[0033] D2. Change the series connection state of the voltage regulating winding according to the actions of all switch modules.

[0034] The series connection states of the voltage regulating winding include: the voltage regulating winding is connected in series with the high-voltage winding in the forward direction, the voltage regulating winding is short-circuited, and the voltage regulating winding is connected in series with the high-voltage winding in the reverse direction.

[0035] The voltage regulating winding is connected in series with the high voltage winding in the forward direction, including:

[0036] When the electronic switch unit is turned on and the normally closed switch is turned off, the position switch K1 is switched to A1-C1 to turn on, and after the position switch K2 is switched to B2-D2 to turn on, the electronic switch unit is turned off, and the current flows from the external connection terminal E1 to the external connection terminal E2 via A1-C1-B2-D2. At this time, the voltage regulating winding corresponding to the switch module is connected from the external connection terminal E1 to the external connection terminal E2; the number of equivalent winding turns on the high-voltage side increases.

[0037] The voltage regulating winding is short-circuited including:

[0038] When the electronic switch unit is turned on and the normally closed switch is turned on, the electronic switch unit is turned off, and the current flows from the normally closed switch of the external connection terminal E1 to the external connection terminal E2;

[0039] The number of equivalent winding turns on the high voltage side remains unchanged.

[0040] The voltage regulating winding is connected in series with the high voltage winding in reverse order, including:

[0041] When the electronic switch unit is turned on and the normally closed switch is turned off, the position switch K1 is switched to B1-D1 to be turned on, and after the position switch K2 is switched to A2-C2 to be turned on, the electronic switch unit is turned off, and the current flows from the external connection terminal E1 to the external connection terminal E2 via A2-C2-B1-D1. At this time, the voltage regulating winding corresponding to the switch module is connected from the external connection terminal E2 to the external connection terminal E1; the number of equivalent winding turns on the high-voltage side is reduced.

[0042] Voltage regulation step size on the high-voltage side:

[0043] Among them, U H and U L They are the highest voltage and the lowest voltage on the high voltage side respectively;

[0044] K = 3 N , N is the number of voltage regulating windings, and K is the number of voltage regulating stages.

[0045] All possible access states S0 of N voltage regulating windings are:

[0046]

[0047] Among them, the S0 matrix has N columns, 3 N OK.

[0048] The relationship between the number of turns M of the voltage regulating winding and the number of turns M0 of the basic winding on the high voltage side is:

[0049] M=T0*M0

[0050] T0 is the corresponding coefficient matrix.

[0051] Coefficient matrix T0:

[0052]

[0053] The equivalent winding turns of high voltage measurement is the sum of the basic winding turns on the high voltage side and the connected voltage regulating winding turns;

[0054] Then the relationship between the equivalent winding turns Meq and the basic winding turns M0 on the high voltage side is: Meq=(1+S0*T0)*M0.

[0055] Compared with the closest prior art, the technical solution provided by the present invention has the following beneficial effects:

[0056] 1. The present invention realizes the voltage regulation function by changing the topological structure and the voltage regulation mode so that the voltage regulation winding vector is connected in series with the high voltage winding.

[0057] 2. The voltage regulation principle provided by the present invention can realize the phase-splitting voltage regulation function of the transformer and the dynamic voltage regulation function according to the low-voltage side voltage.

[0058] 3. The present invention simplifies equipment configuration, reduces the volume of distribution transformers and unnecessary costs.

[0059] 4. The present invention eliminates the hidden dangers of the original electric switch mechanism, makes it easier to quickly complete selection and switching through software control, and effectively prolongs the service life of the switch.

[0060] 5. The electronic switch unit used in the present invention is not connected in series with the high-voltage side winding under normal working conditions, so there is no drive and power loss. BRIEF DESCRIPTION OF THE DRAWINGS

[0061] Figure 1 It is a structural schematic diagram of a phase circuit in an embodiment of the present invention;

[0062] Figure 2 It is a schematic diagram of the circuit structure of the switch module and the voltage regulating winding of the present invention;

[0063] Figure 3 It is a structural schematic diagram of the voltage regulation control module of the present invention;

[0064] Figure 4 The electronic switch unit form 1 of the present invention;

[0065] Figure 5 The electronic switch unit form 2 of the present invention;

[0066] Figure 6 The electronic switch unit form 3 of the present invention;

[0067] Figure 7 The electronic switch unit form 4 of the present invention;

[0068] Figure 8 A logical schematic diagram of the voltage regulating winding of the present invention being put into operation or withdrawn;

[0069] Fig. 9 The figure is a flow chart of the voltage regulation process of the transformer of the present invention. DETAILED DESCRIPTION

[0070] The technical solution of the present invention is further described in detail below in conjunction with the accompanying drawings.

[0071] like Figure 1 As shown, a high-precision arc-free on-load automatic voltage-regulating distribution transformer comprises: a transformer high-voltage winding, a transformer low-voltage winding, n voltage-regulating windings, n switch modules, and a control module. Where n is a positive integer (usually 2 or 3), and each voltage-regulating winding is connected to a switch module.

[0072] like Figure 2 As shown, the switch modules include: two position switching switches (or switches with similar switching functions) K1 and K2, an electronic switch unit K3, and a normally closed switch K4; one end of the switch module is connected to the voltage regulating winding, and the other end E1 and E2 are connected in series in the high-voltage winding; the A1 and A2 terminals of the position switching switches K1 and K2 of the switch module are connected to E1, and the D1 and D2 terminals are connected to E2; the B1 and C1 terminals of the position switching switch K1 of the switch module are connected to the X1 end of the voltage regulating winding, and the B2 and C2 terminals of the position switching switch K2 of the switch module are connected to the X2 end of the voltage regulating winding; one end of the electronic switch unit K3 of the switch module is connected to E1, and the other end is connected to E2; one end of the normally closed switch K4 of the switch module is connected to E1, and the other end is connected to E2.

[0073] like Figure 3 As shown, the control module mainly includes: a power supply unit, a measuring unit, an operation control unit and a trigger output unit. The on-load voltage-regulating transformer of this embodiment can control the output voltage of the low-voltage side within a given range according to the actual voltage fluctuation of the distribution network where the distribution transformer is located. By controlling the opening and closing logic of the switch module, the voltage-regulating winding can be connected to the high-voltage winding in the forward direction, reverse direction or short circuit, and the equivalent number of turns of the high-voltage winding can be changed, thereby stabilizing the voltage output of the low-voltage side of the distribution transformer within a large range. In any voltage regulation conversion process of the on-load transformer switch module, the electronic switch unit K3 is first turned on, and then the position switching switch or the normally closed switch K4 is adjusted to be on and off, thereby eliminating the generation of arcs during the conversion process.

[0074] At the same time, the present invention provides a method for determining the relationship between the voltage regulation range, voltage regulation level, number of voltage regulation windings, voltage regulation step, and number of voltage regulation winding turns of the on-load voltage regulation device of the distribution transformer, forming a logical method for the input or output of the transformer voltage regulation winding vector and a transformer voltage regulation process. The method determines the voltage regulation step according to the voltage regulation range and the number of voltage regulation windings required, thereby determining the number of turns of the voltage regulation winding. Since the voltage regulation level of the transformer increases exponentially with the increase in the number of voltage regulation windings, according to this method, under the premise of a given voltage regulation step, by increasing the number of voltage regulation windings, the voltage regulation range is greatly increased; under the premise of any given voltage regulation range, by increasing the number of voltage regulation windings, the voltage regulation step can be greatly reduced and the regulation accuracy can be increased.

[0075] In this embodiment, by controlling the on and off states of each switch of the switch module, on the one hand, the correspondingly connected voltage regulating winding vector can be connected in series with the high-voltage winding, thereby changing the equivalent number of turns of the high-voltage winding; on the other hand, the generation of arcs during the voltage regulation process can be eliminated through the action of the electronic switch unit.

[0076] by Figure 2 Take the switch module and voltage regulating winding shown as an example:

[0077] In case 1, the electronic switch unit K3 is turned on, the switch K4 is turned on, and then the electronic switch unit K3 is turned off. At this time, the current flows directly from the terminal E1 to the terminal E2 through K4, which is equivalent to the voltage regulating winding being short-circuited, that is, the voltage regulating winding corresponding to the switch module is not connected to the high-voltage winding, and the number of turns of the equivalent winding on the high-voltage side of the distribution transformer remains unchanged.

[0078] In case 2, the electronic switch unit K3 is turned on, the switch K4 is turned off, and the position switching switch K1 is switched to A1-C1 to be turned on, the position switching switch K2 is switched to B2-D2 to be turned on, and the electronic switch unit K3 is turned off. At this time, the current flows from terminal E1 to terminal E2 through A1-C1-B2-D2. At this time, it is equivalent to that the voltage regulating winding corresponding to the switch module is connected from terminal E1 to terminal E2, that is, the voltage regulating winding is connected in series with the high-voltage winding in the forward direction, and the number of turns of the equivalent winding on the high-voltage side of the distribution transformer increases.

[0079] In case 3, the electronic switch unit K3 is turned on, the switch K4 is turned off, and the position switching switch K1 is switched to B1-D1 to be turned on, the position switching switch K2 is switched to A2-C2 to be turned on, and the electronic switch unit K3 is turned off. At this time, the current flows from terminal E1 to terminal E2 through A2-C2-B1-D1. At this time, it is equivalent to that the voltage regulating winding corresponding to the switch module is connected from terminal E2 to terminal E1, that is, the voltage regulating winding is connected in series with the high-voltage winding in reverse, and the number of turns of the equivalent winding on the high-voltage side of the distribution transformer is reduced.

[0080] By coordinating the on and off of each switch in the switch module, the voltage regulating winding corresponding to the switch module can be introduced into the high-voltage winding in a forward, reverse or short-circuited manner to achieve the purpose of increasing, reducing or maintaining the number of equivalent winding turns of the original high-voltage winding. By using multiple voltage regulating windings and switch modules together, the regulation level of the voltage regulating winding can be several times the order of magnitude, greatly increasing the voltage regulation range and accuracy of the distribution transformer, so that the fluctuation of the load-end voltage is maintained within a reasonable range.

[0081] As a specific implementation method, the winding direction of the voltage regulating winding is the same as the winding direction of the high-voltage winding.

[0082] by Figure 2 Taking the switch module and voltage regulating winding shown as an example, when the winding direction of the voltage regulating winding is the same as that of the high-voltage winding, the polarity of one end of the voltage regulating winding is the same as that of the high-voltage winding. When the switch K4 is turned on, the current flows directly from the terminal E1 to the terminal E2 through K4, which is equivalent to the voltage regulating winding being short-circuited, that is, the voltage regulating winding corresponding to the switch module is not connected in series with the high-voltage winding, and the number of turns of the equivalent winding on the high-voltage side of the distribution transformer remains unchanged.

[0083] When switch K4 is disconnected, position switch K1 is switched to A1-C1 for conduction, and position switch K2 is switched to B2-D2 for conduction. At this time, the current flows from terminal E1 to terminal E2 via A1-C1-B2-D2, which is equivalent to the voltage regulating winding corresponding to the switch module being connected from terminal E1 to terminal E2, that is, the voltage regulating winding is connected in series with the high-voltage winding in the forward direction, and the number of turns of the equivalent winding on the high-voltage side of the distribution transformer increases. When switch K4 is disconnected, position switch K1 is switched to B1-D1 for conduction, and position switch K2 is switched to A2-C2 for conduction. At this time, the current flows from terminal E1 to terminal E2 via A2-C2-B1-D1, which is equivalent to the voltage regulating winding corresponding to the switch module being connected from terminal E2 to terminal E1, that is, the voltage regulating winding is connected in series with the high-voltage winding in the reverse direction, and the number of turns of the equivalent winding on the high-voltage side of the distribution transformer decreases.

[0084] like Figure 2 As shown, the position switch corresponding to the switch module has four terminals, and its function is to change the conduction state of two of its four terminals to the conduction of the other two terminals, and there will be no simultaneous conduction. For example, the position switch K1 can only be conducted between A1-C1 or between B1-D1, or change between the two, such as the conduction between A1-C1 is changed to the conduction between B1-D1, and there will be no other states. The position switch can be a magnetic latching relay in specific implementation.

[0085] like Figure 3The voltage regulation control module structure diagram shown in the figure mainly includes a power supply unit, a measurement unit, an operation control unit, and a trigger output unit. The power supply unit is connected to the high voltage winding (such as Figure 2 The measuring unit is mainly used to measure the output voltage of the low-voltage side of the transformer, and provide a reference for the voltage regulation of the voltage regulating transformer, usually with the rated voltage of the low-voltage side as the adjustment target.

[0086] The given voltage is the output target voltage of the transformer, which is set based on the voltage at the low-voltage side outlet of the transformer and the voltage at the end of the low-voltage line being within the qualified range, and is usually the rated voltage.

[0087] The operation control unit calculates the number of winding turns that should be adjusted on the high-voltage side according to the difference between the current low-voltage side voltage and the given voltage provided by the measurement unit, and generates the expected voltage-regulating winding state matrix and voltage-regulating logic. The trigger output unit outputs the corresponding control signal in a time sequence according to the voltage-regulating logic generated by the operation control unit, turns on or off the corresponding switch, and realizes that the voltage-regulating winding is connected in series to the high-voltage side in a forward, reverse or short-circuit manner according to the voltage-regulating logic, thereby achieving the purpose of voltage regulation.

[0088] like Figure 4 As shown, as a specific implementation of the electronic switch unit K3 in the switch module, the electronic switch unit K3 includes two thyristors SCR1, a thyristor SCR2 and a varistor R1 connected in reverse parallel, the anode of the thyristor SCR1 is respectively connected to the cathode of the thyristor SCR2 and one end of the varistor R1, the anode of the thyristor SCR2 is respectively connected to the cathode of the thyristor SCR1 and the other end of the varistor R1, and the two common connection terminals P and Q are respectively used as the external connection terminals of the electronic switch unit K3. Since the above two thyristors can realize their own conduction or shutdown under the action of the control signal, the bidirectional on-off function of the electronic switch unit K3 under different conditions can be realized. In this switch unit, the varistor R1 connected in parallel with the two thyristors is used to limit the voltage at both ends of the thyristor to protect the thyristor.

[0089] like Figure 5 As shown, as another specific implementation of the electronic switch unit K3 in the switch module, the electronic switch unit K3 includes: two insulated gate bipolar transistors (IGBT) T1, T2 and two diodes D1, D2, the emitter of the IGBT T1 is respectively connected to the emitter of the IGBT T2, the anode of the diode D1, and the anode of the diode D2, the collector of the IGBT T1 and the cathode of the diode D2 are respectively connected to the external common connection terminal P, and the collector of the IGBT T2 and the cathode of the diode D1 are respectively connected to the external common connection terminal Q.

[0090] like Figure 6 As shown, as another specific implementation of the electronic switch unit K3 in the switch module, the electronic switch unit includes: two insulated gate bipolar transistors (IGBT) T3, T4 and two diodes D3, D4, the collector of the IGBT T3 is respectively connected to the collector of the IGBT T4, the anode of the diode D1, and the anode of the diode D2, the emitter of the IGBT T3 and the cathode of the diode D4 are respectively connected to the external common connection terminal P, and the emitter of the IGBT T4 and the cathode of the diode D3 are respectively connected to the external common connection terminal Q.

[0091] like Figure 7 As shown, as another specific implementation of the electronic switch unit K3 in the switch module, the electronic switch unit includes: an insulated gate bipolar transistor (IGBT) T5 and four diodes D5, D6, D7, and D8, the collector of the insulated gate bipolar transistor T5 is respectively connected to the cathode of the diode D5 and the cathode of the diode D6, the emitter of the insulated gate bipolar transistor T5 is respectively connected to the anode of the diode D7 and the anode of the diode D8, the external common connection terminal P is respectively connected to the cathode of the diode D7 and the anode of the diode D5, and the external common connection terminal Q is respectively connected to the cathode of the diode D8 and the anode of the diode D6.

[0092] In each transformation process of the series connection state of the voltage regulating winding corresponding to the switch module on the high-voltage side, such as transformation from forward series connection to short-circuit connection state, from forward series connection to reverse connection state, from short-circuit connection state to reverse connection state, and reverse connection state to short-circuit connection state, the electronic switch unit K3 is first turned on in the switch module, and then other switches K1, K2 and K4 are switched or turned on according to the state that the voltage regulating winding needs to be connected to the high-voltage side, and finally the electronic switch unit K3 is disconnected, and a transformation process is completed. The electronic switch unit K3 plays a transitional role in the switching process of the forward series connection, reverse series connection and short-circuit connection of the entire voltage regulating winding.

[0093] from Figures 4 to 7 In the specific implementation of the four electronic switch units K3, since electronic switches such as IGBT and thyristor are used, especially IGBT has the advantages of fast switching speed, good thermal stability, low driving power, simple driving circuit, etc., K3 not only has good switching characteristics, but also eliminates the generation of conventional switching arcs during the transition process.

[0094] like Figure 2 The high and low voltage windings and voltage regulating windings shown are only the voltage regulating schematic connection diagrams of one phase of the three-phase windings of the distribution transformer in actual applications. The connection methods of the other two phases are the same. Figure 2 same.

[0095] The present invention provides a method for determining the relationship between the voltage regulation range, voltage regulation level (directly determines the voltage regulation accuracy), number of voltage regulation windings, voltage regulation step length, and number of turns of the voltage regulation winding of the on-load voltage regulation device of the distribution transformer. Since the voltage ratio between the high-voltage side and the low-voltage side of the distribution transformer is proportional to the number of turns of the high-voltage and low-voltage windings, the voltage on the low-voltage side can be adjusted to a reasonable range by adjusting the equivalent winding on the high-voltage side. The voltage regulation range U of the distribution transformer H -U L , voltage regulation level K, voltage regulation winding number N, and voltage regulation winding turns M are mutually influential, among which U H ,U L For example, the voltage regulation level K on the high-voltage side is related to the number of voltage regulation windings N, and the voltage regulation range U on the high-voltage side is H -U L It is equal to the product of the voltage regulation level K and the basic voltage regulation step Ui. The basic voltage regulation step Ui is related to the number of turns M of the voltage regulation winding.

[0096] The following first determines the relationship between the voltage regulation level K and the number of voltage regulation windings N:

[0097] Assuming that the number of voltage regulating windings is N=3, the transformation of the switch module corresponding to each voltage regulating winding can realize the connection of the voltage regulating winding to the high-voltage winding in series, reverse series and short circuit. That is, the state of the switch module is closely related to the connection state of the corresponding voltage regulating winding, and the state of each switch module corresponds to a different total number of equivalent winding turns on the high-voltage side.

[0098]

[0099] For the convenience of description, the state function Si of the switch module is defined according to formula (1): when switch K4 is disconnected, the position switch K1 is switched to A1-C1 for conduction, and the position switch K2 is switched to B2-D2 for conduction. At this time, the current flows from terminal E1 to terminal E2 via A1-C1-B2-D2. At this time, the voltage regulating winding corresponding to the switch module is connected from terminal X1 to terminal X2, that is, the voltage regulating winding is connected in series with the high-voltage winding in the forward direction, and Si=1; when switch K4 is turned on, The current flows directly from terminal E1 to terminal E2 via K4, which is equivalent to the voltage regulating winding being short-circuited, Si=0; when switch K4 is disconnected, the position switching switch K1 is switched to B1-D1 for conduction, and the position switching switch K2 is switched to A2-C2 for conduction. At this time, the current flows from terminal E1 to terminal E2 via A2-C2-B1-D1, which is equivalent to the voltage regulating winding corresponding to the switch module being connected from terminal X2 to terminal X1, that is, the voltage regulating winding is connected in series with the high-voltage winding in reverse, Si=-1.

[0100] Since the switch module corresponding to each voltage regulating winding has three different states to connect the voltage regulating winding, in order to characterize all situations, based on formula (1), the voltage regulating state matrix of the three voltage regulating windings is constructed. When the number of voltage regulating coils is N=2, the number of voltage regulating stages is 9; as shown in formula (2), when the number of voltage regulating coils is N=3, the number of voltage regulating stages is 27; this state matrix includes all possible connection states of the three voltage regulating windings.

[0101]

[0102] It can be seen that when the number of voltage regulating coils is N=4, the number of voltage regulating stages is 81; when the number of voltage regulating coils is N, the number of voltage regulating stages is 3 N , then the matrix of all possible access states of N voltage regulating coils is:

[0103]

[0104] The relationship between the voltage regulation level K and the number of voltage regulation windings N is:

[0105] K = 3 N (N=1, 2, 3) (4)

[0106] Basic step length of voltage regulation:

[0107] Assume that the basic number of turns of the high-voltage side winding is M0, the given voltage on the high-voltage side is U0, and the basic step length of the voltage regulation is U i The corresponding number of turns of the winding is M i :

[0108]

[0109] Assume M i =0.01M0, 0.01 is the basic voltage regulation multiple; when the number of voltage regulating coils is N=3, as shown in formula (4), the base of the formula corresponding to the voltage regulation level is 3, so the multiple relationship of different voltage regulating windings should also be 3, and the number of turns of the three voltage regulating windings are 0.01M0, 0.03M0, and 0.09M0 respectively. The relationship between the voltage regulating winding M and the number of turns M0 of the basic winding on the high voltage side is expressed by a matrix as follows:

[0110]

[0111] T is the corresponding coefficient matrix, and the coefficient matrix T0 of N voltage regulating coils is:

[0112]

[0113] Since the number of high-voltage equivalent winding turns is the sum of the number of high-voltage side basic winding turns and the number of turns of the connected voltage regulating winding, the number of equivalent winding turns of the high-voltage winding can be calculated in the form of a matrix according to equations (2) and (7). When the number of voltage regulating coils is N = 3, the number of high-voltage side equivalent winding turns Meq is:

[0114]

[0115] From formula (8), it can be seen that after the three voltage regulating winding vectors are connected to the high-voltage winding, the high-voltage side equivalent winding has 27 adjustable levels, and the number of turns varies from 87% to 113% of the original number of high-voltage winding turns, that is, it varies from -13% to 13% based on the original number of high-voltage turns. Therefore, the output voltage of the low-voltage side of the distribution transformer also varies from 87% to 113% of the given voltage.

[0116] Since the regulation target of the voltage regulating distribution transformer is to keep the voltage on the low voltage side stable, it can also be considered that when the high voltage side is within the range of 87%-113% of the given voltage, the voltage regulating transformer can keep the low voltage side voltage at a constant given output voltage.

[0117] From this implementation case, we can see that when the voltage regulation range is given, as long as the number of voltage regulating windings is increased, the voltage regulation level can be increased, the regulation accuracy can be increased, and the basic voltage regulation multiple can be reduced at the same time; when the number of voltage regulating windings is given, the voltage regulation level is also determined, and as long as the basic voltage regulation multiple is increased, the voltage regulation range can be greatly increased, which points out the direction for developing corresponding products for different needs.

[0118] The present invention provides a logic method and a voltage regulation process of a transformer for determining the input or output of a voltage regulation winding vector according to the voltage regulation change requirements, under the premise that the number and turns of the voltage regulation winding have been determined. The purpose of automatic voltage regulation of a distribution transformer is to maintain the stability of the voltage on the low voltage side by adjusting the equivalent turns on the high voltage side. Therefore, different high voltage side voltages correspond to different voltage regulation equivalent turns, and the voltage regulation process is the process of inputting or outputting different windings.

[0119] like Figure 8As shown, the voltage regulation logic of the transformer is still explained by taking the number of voltage regulating windings N = 3 and the number of turns of the voltage regulating windings as 0.01M0, 0.03M0, and 0.09M0 respectively. From equations (2) and (8), it can be seen that each equivalent number of turns on the high voltage side in equation (8) corresponds to a voltage regulation state matrix in equation (2) to reflect the input or output state of different voltage regulating windings. For example, when the equivalent number of turns in equation (8) is 0.93M0, the corresponding voltage regulation state matrix is ​​[-1, 1, -1], and the voltage regulation state matrix corresponding to 1.01M0 is [1, 0, 0]. If the corresponding equivalent winding needs to be changed from 0.93M0 to 1.01M0 according to the voltage regulation requirements, it is only necessary to adjust the corresponding voltage regulation state matrix from [-1, 1, -1] to [1, 0, 0], corresponding to 0. The state quantity of the 01M0 voltage regulating winding changes from -1 to 1, that is, the voltage regulating winding changes from the reverse series connection state to the forward series connection state, but due to the short-circuit transition process of the electronic switch branch, its actual transformation process is that the state quantity changes from -1 to 0, and then to 1, that is, the voltage regulating winding changes from the reverse series connection state to the short-circuit state, and then changes to the forward series connection state; the state quantity of the corresponding 0.03M0 voltage regulating winding changes from 1 to 0, that is, the voltage regulating winding changes from the forward series connection state to the short-circuit state; the state quantity of the corresponding 0.09M0 voltage regulating winding changes from -1 to 0, that is, the voltage regulating winding changes from the reverse series connection state to the short-circuit state; the order is to change the state of the voltage regulating winding corresponding to the leftmost variable of the state matrix first, and then change the state of the voltage regulating winding corresponding to the rightmost variable in turn, until the last one.

[0120] like Fig. 9 The figure shows the flow chart of the transformer on-load voltage regulation process. The steps are as follows: first, determine whether the difference between the low-voltage side output voltage and the given voltage is greater than the corresponding voltage regulation step length on the low-voltage side (the voltage regulation step length is the ratio of the high-voltage side voltage regulation step length Ui to the transformer ratio, such as Figure 8In the example, Ui=0.01*10kV=100V, then the corresponding voltage regulation step size of the low voltage side is 100V / 10 / 0.4=4V). If it is greater than the voltage regulation step size, the state matrix S corresponding to each voltage regulating winding on the current high voltage side is determined, and the state matrix S' corresponding to each voltage regulating winding on the high voltage side when the current low voltage side voltage is adjusted to the given voltage is calculated according to the difference between the current voltage on the low voltage side and the given voltage; then determine whether the first bit (the leftmost bit of the matrix) state quantity corresponding to the state matrices S and S' of the voltage regulating winding has changed. If so, the switch control logic of the corresponding voltage regulating winding is formed according to the change of the state bit. If there is no change, continue to determine whether the second bit state quantity corresponding to the state matrices S and S' has changed. If so, the switch control logic of the corresponding voltage regulating winding is formed according to the change of the state bit. If there is no change, continue to determine the next bit to the right until the last bit. Finally, after the comparison between the state matrices S and S' is completed, the switch control logic of each voltage regulating winding is formed according to the above, and the control switches are operated in sequence. From left to right, that is, the voltage regulating winding with fewer turns is adjusted first, and then the voltage regulating winding with more turns is adjusted. The series connection state of each voltage regulating winding is adjusted to achieve the voltage regulation purpose and end the voltage regulation process.

[0121] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Ordinary technicians in the relevant field can still modify or make equivalent substitutions to the specific implementation methods of the present invention with reference to the above embodiments. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention are within the scope of protection of the claims of the present invention to be approved.

Claims

1. A voltage regulation method for an arc-free on-load automatic voltage regulation distribution transformer, characterized in that: The steps include: A. Determine the difference between the current output voltage of the low voltage side and the given voltage; B. comparing the difference with the voltage regulation step size on the low pressure side; C. Form the control logic of the switch module according to the change of each bit of the high-voltage side voltage regulating winding state matrix; D. According to the control logic of all switch modules, adjust the series connection state of the voltage regulating winding in turn; The step B comprises: B1. If the difference is less than the voltage adjustment step, return to continue to determine the size of the difference; B2. If the difference is greater than the voltage regulation step, determine that the state matrix corresponding to the current high-voltage side voltage regulation winding is S; The step C comprises: C1. Determine whether the first state quantity of the state matrix S and S' has changed; C2. If the first bit state quantity changes, a control logic of the switch module corresponding to the state bit is formed according to the change of the first bit state quantity; C3. If the first state quantity does not change, continue to determine whether the second state quantity of the state matrix S and S' has changed; C4. If the second bit state quantity changes, the control logic of the switch module corresponding to the state bit is formed according to the change of the second bit state; C5. If the state of the second bit does not change, continue to judge the next bit until the last bit.

2. The voltage regulation method according to claim 1, characterized in that: The step B2 comprises: When the current low-voltage side voltage is adjusted to the given voltage, the state matrix corresponding to the high-voltage side voltage regulating winding is S'.

3. The voltage regulation method according to claim 1, characterized in that: The step D comprises: D1. According to the control logic of the switch module, the action of all switch modules is controlled in sequence; D2. According to the actions of all the switch modules, the series connection state of the voltage regulating winding is changed.

4. The voltage regulation method according to claim 3, characterized in that: The series connection state of the voltage regulating winding includes: the voltage regulating winding is connected in series with the high-voltage winding in a forward direction, the voltage regulating winding is short-circuited, and the voltage regulating winding is connected in series with the high-voltage winding in a reverse direction.

5. The voltage regulation method according to claim 4, characterized in that: The voltage regulating winding is positively connected in series with the high-voltage winding and comprises: When the electronic switch unit is turned on and the normally closed switch is turned off, the position switch K1 is turned on to A1-C1, and the position switch K2 is turned on to B2-D2, and then the electronic switch unit is turned off, and the current flows from the external connection terminal E1 to the external connection terminal E2 via A1-C1-B2-D2. At this time, the voltage regulating winding corresponding to the switch module is connected from the external connection terminal E1 to the external connection terminal E2; The number of equivalent winding turns on the high voltage side increases.

6. The voltage regulation method according to claim 4, characterized in that: The voltage regulating winding is short-circuited including: When the electronic switch unit is turned on and the normally closed switch is turned on, the electronic switch unit is turned off, and the current flows from the external connection terminal E1 to the external connection terminal E2 through the normally closed switch; The number of equivalent winding turns on the high voltage side remains unchanged.

7. The voltage regulation method according to claim 4, characterized in that: The voltage regulating winding is connected in series with the high voltage winding in reverse direction, including: When the electronic switch unit is turned on and the normally closed switch is turned off, the position switch K1 is turned on to B1-D1, and the position switch K2 is turned on to A2-C2, and then the electronic switch unit is turned off, and the current flows from the external connection terminal E1 to the external connection terminal E2 via A2-C2-B1-D1. At this time, the voltage regulating winding corresponding to the switch module is connected from the external connection terminal E2 to the external connection terminal E1; The number of equivalent winding turns on the high voltage side is reduced.

8. The voltage regulation method according to claim 1, characterized in that: The voltage regulation step size on the high-pressure side is: Among them, U H and U L are respectively the highest voltage and the lowest voltage on the high voltage side; k=3 N , N is the number of voltage regulating windings, and k is the number of voltage regulating stages.

9. The voltage regulating method according to claim 8, characterized in that: All possible access states S0 of N voltage regulating windings are: Among them, the S0 matrix has N columns, 3 N OK.

10. The voltage regulating method according to claim 9, characterized in that: The relationship between the number of turns M of the voltage regulating winding and the number of turns M0 of the basic winding on the high voltage side is: M=T0*M0 T0 is the corresponding coefficient matrix.

11. The voltage regulating method according to claim 10, characterized in that: The coefficient matrix T0:

12. The voltage regulating method according to claim 11, characterized in that: The number of equivalent winding turns on the high-voltage side is the sum of the number of basic winding turns on the high-voltage side and the number of turns of the connected voltage regulating winding; The relationship between the equivalent winding turns Meq and the basic winding turns M0 on the high voltage side is: Meq=(1+S0*T0)*M0.

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