A staggered parallel multi-speed transformer on-load voltage regulation circuit with polarity conversion

Abstract

The present invention relates to the field of distribution transformers, and specifically to an on-load voltage regulation circuit of a staggered parallel multi-speed transformer with polarity conversion, comprising a main winding, a polarity conversion switch, a voltage regulating winding, a transition switching unit, a rated voltage branch, and a plurality of voltage regulating branches; the present technical solution sets a polarity conversion switch between the main winding and the voltage regulating winding, and realizes positive and negative voltage regulation by adjusting the independent contact connection end of the polarity conversion switch; one end of each voltage regulating branch is respectively connected to the two end taps and each middle tap of the voltage regulating winding; the other end is adjacently staggered and paralleled into two groups, respectively connected to the two input ends of the transition switching unit, the input end of the rated voltage branch is connected to the output end of the main winding, and the output end of the rated voltage branch is connected to the output end of the voltage regulating circuit. The beneficial effects of the present invention are to reduce the on-off frequency of the on-off switch, increase the service life of the corresponding voltage regulating switch, and in the voltage regulation process, the transition voltage changes with the voltage regulating gear, and there is no need to jump the gear to regulate the voltage.

Description

Technical Field

[0001] The invention relates to the field of distribution transformers, and in particular to an on-load voltage regulation circuit for a transformer. Background Art

[0002] In the patent with application number 201610121960 and title: "A permanent magnetic vacuum on-load voltage regulating switch, transformer and on-load voltage regulating method", a method for on-load voltage regulating is provided, which uses two vacuum interrupters to form the main circuit and transition circuit structure respectively. The key points of this technical solution are: during normal operation, the vacuum interrupter of the main circuit is connected, and the main circuit is in the on state, the vacuum interrupter of the transition circuit is disconnected, and the transition circuit is in the off state, and the voltage regulating winding connected to the main circuit determines the external voltage supply gear of the circuit. When switching gears, the vacuum interrupter of the transition circuit is closed first, and the transition circuit is in the on state, and then the vacuum interrupter of the main circuit is disconnected, and the main circuit is in the off state. At this time, the shift switch completes the shift without current, and no arc is generated. The transition circuit provides a transition voltage for the circuit when the gear is switched to ensure that the circuit will not interrupt the external voltage supply. However, the multi-speed voltage regulating circuit designed according to this method has the following shortcomings:

[0003] 1. Each time the gear is switched, the vacuum interrupter of the main circuit must be opened and closed once, and the vacuum interrupter of the transition circuit must also be closed and opened once. The vacuum interrupters of the main circuit and transition circuit are the devices with the highest switching frequency in the circuit. The upper limit of their switching times determines the service life of the voltage regulator designed according to the circuit. According to the standard requirements, the mechanical life of the on-load voltage regulator must reach 500,000 times, that is, the voltage regulator performs 500,000 tap change operations when the contacts are not energized and all the tapping ranges are used. According to this voltage regulation circuit, the on-load voltage regulator with 5 gears performs a voltage regulation cycle, and the main circuit and transition circuit will operate 4*50=2 million times. For the on-load voltage regulator with 9 gears, the main circuit and transition circuit will operate 8*50=4 million times. At present, the mechanical life of the vacuum interrupter is required to be between 800,000 and 1.2 million times. It can be seen that the mechanical life of the voltage regulator produced according to this voltage regulation circuit is a severe test, and it is estimated that the mechanical life cannot meet the standard requirements.

[0004] 2. The transition circuit is fixed to a certain tap. Any voltage adjustment must first return to this fixed tap, and then adjust to the gear that needs voltage adjustment, commonly known as jump-shift voltage adjustment. The instantaneous change of voltage will produce a very high amplitude operating overvoltage. The higher the instantaneous rate of voltage change, the higher the amplitude of the overvoltage generated, which is extremely harmful to electronic products connected to the power grid. Therefore, the standard does not allow jump-shift voltage adjustment.

[0005] The patent with application number: 201721680735.9, titled: "A method for on-load voltage regulation using a double-throw switch", has made improvements to Patent 201610121960: the structure of the tapping coil is simpler; the transition circuit is connected to the rated gear instead of the end of the main winding of the transformer, so that the voltage fluctuation is smaller when shifting. This patent has multiple variations. But the two fundamental points are the same as Patent 201610121960: 1. Every time the gear is switched, the vacuum interrupter of the main circuit must be opened and closed once, and the transition circuit must also be closed and opened once. The upper limit of the number of on-off times determines the service life of the voltage regulating switch designed according to the circuit. 2. Its transition circuit is fixedly connected to the tap of the main winding, and the voltage regulation is still a jump gear voltage regulation, which is not allowed by the standard.

[0006] In patent 201820286271.1, patent 201721680735.9 was improved by adding transition circuit selection switches (the number varies according to the voltage regulating gear, and 2 transition circuit selection switches are required for 5 gears). The transition circuit is not fixedly connected to the main tapping gear of the voltage regulating winding, but changes with the gear through the transition circuit selection switch. However, the defect that "every time the gear is switched, the vacuum interrupter of the main circuit must be opened and closed once, and the transition circuit must also be closed and opened once. The upper limit of the number of on and off times determines the service life of the voltage regulating switch designed according to this circuit" remains unchanged. And as the number of switch gears increases, the number of transition circuit selection switches also increases, and the switch structure tends to be complex. Summary of the invention

[0007] The purpose of the present invention is to design a new circuit structure to replace the design of the transition circuit and the main circuit, reduce the on-off frequency of the vacuum interrupter in the circuit during the voltage regulation process, so as to achieve the purpose of increasing the service life of the corresponding voltage regulating switch; and in the voltage regulation process, make the transition voltage different with the different gears of the transition switching, reduce the voltage fluctuation during the voltage regulation, and avoid the problem of jump voltage regulation; at the same time, add the positive and negative voltage regulation functions to the on-load voltage regulation circuit, so as to achieve the purpose of reducing the number of voltage regulating windings, simplifying the transformer structure and reducing the manufacturing cost under the premise of the same number of gears.

[0008] In order to achieve the above-mentioned object of the invention, the technical solution of the present invention is:

[0009] A staggered parallel multi-speed transformer on-load voltage regulation circuit with polarity conversion, comprising a main winding, a polarity conversion switch, a voltage regulation winding, a transition switching unit, a rated voltage branch and a plurality of voltage regulation branches;

[0010] The voltage regulating winding is composed of N coils wound in the same direction connected end to end in sequence, the voltage regulating winding includes two end taps and N-1 middle taps, the main winding input end is connected to the input end of the voltage regulating circuit, and the main winding output end is connected to the common contact of the polarity conversion switch; the two independent contacts of the polarity conversion switch are respectively connected to the two end taps of the voltage regulating winding;

[0011] The transition switching unit includes two input ends and one output end, and the output end of the transition switching unit serves as the output end of the voltage regulating circuit; an on-off switch and a transition resistor connected in parallel with each other are connected in series between the first input end of the transition switching unit and the output end of the transition switching unit, and the second input end of the transition switching unit is connected to the output end of the transition switching unit (the output end of the transition switching unit is also the output end of the voltage regulating circuit).

[0012] Preferably, the transition switching unit is composed of a transition resistor and an on-off switch in parallel, the first input terminal of the transition switching unit is connected to the first end of the transition resistor and the first end of the on-off switch, the second input terminal of the transition switching unit also serves as the output terminal of the transition switching unit, and the output terminal of the transition switching unit is connected to the second end of the transition resistor and the second end of the on-off switch.

[0013] Preferably, the on-off switch in the transition switching unit uses a vacuum interrupter, so that the electric arc will not contaminate the transformer oil.

[0014] An on-off switch is connected in series on each voltage regulating branch, and one end of each voltage regulating branch is respectively connected to the two end taps and each middle tap of the voltage regulating winding; the other end of each voltage regulating branch is adjacently and alternately connected in parallel to form two groups, and respectively connected to the two input ends of the transition switching unit; preferably, the on-off switch uses a vacuum arc extinguishing chamber, and the electric arc will not contaminate the transformer oil.

[0015] An on-off switch is connected in series on the rated voltage branch, one end of the rated voltage branch is connected to the output end of the main winding; the other end can be connected to any end of the transition switching unit. Preferably, the rated voltage branch is connected to the first input end of the transition switching unit, and the output current does not pass through the switch in the transition switching unit at the rated gear; the on-off switch preferably uses a vacuum interrupter, and the arc will not contaminate the transformer oil.

[0016] Specifically, the voltage regulating coils of the voltage regulating winding are connected head to tail, and the number of voltage regulating coils in the voltage regulating winding is determined according to the gear of the voltage regulating circuit to be designed. For a five-speed voltage regulating circuit, the voltage regulating winding is composed of two voltage regulating coils; for a seven-speed voltage regulating circuit, the voltage regulating winding is composed of three voltage regulating coils. The voltage regulating winding can be connected in series to the beginning, middle or end of the main winding of the transformer to form end, middle or neutral point voltage regulation.

[0017] A voltage regulating winding tap is provided at each end of the voltage regulating coil, wherein adjacent voltage regulating coil ends share one tap, that is, the number of voltage regulating coils constituting the voltage regulating winding plus one is the number of voltage regulating winding taps. From one end to the other end of the entire voltage regulating winding, the taps of each voltage regulating coil are defined as 1, 2 to n in sequence. The tap numbered 1 and the tap numbered n are the taps at the two ends of the voltage regulating winding.

[0018] The number of the voltage regulating branches is consistent with the number of the voltage regulating winding taps, and one end of each of the voltage regulating branches is connected to a corresponding voltage regulating winding tap.

[0019] The voltage regulating branch connected to tap No. 1 is defined as branch No. 1, the voltage regulating branch connected to tap No. 2 is defined as branch No. 2, and so on, until branch No. n.

[0020] There are two ways to connect the other end of each voltage regulating branch:

[0021] Connection mode 1: the other end of all odd-numbered voltage regulating branches is connected to the second input end of the transition switching unit; the other end of all even-numbered voltage regulating branches is connected to the first input end of the transition switching unit.

[0022] Connection mode 2: the other ends of all even-numbered voltage regulating branches are connected to the second input end of the transition switching unit; the other ends of all odd-numbered voltage regulating branches are connected to the first input end of the transition switching unit.

[0023] Since the second input end of the transition switching unit is connected to the output end of the entire voltage regulating circuit, the voltage regulating branch connected to the second input end of the transition switching unit is defined as a directly connected voltage regulating branch. Since a parallel resistor and vacuum arc chamber structure are connected in series between the first input end of the transition switching unit and the output end of the voltage regulating circuit, the voltage regulating branch connected to the first input end of the transition switching unit is defined as a non-directly connected voltage regulating branch.

[0024] In connection mode 1, odd-numbered voltage regulating branches are directly connected voltage regulating branches; even-numbered voltage regulating branches are non-directly connected voltage regulating branches.

[0025] In connection mode 2, odd-numbered voltage regulating branches are non-directly connected voltage regulating branches; even-numbered voltage regulating branches are directly connected voltage regulating branches.

[0026] When the polarity conversion switch is in the upper on state, the polarity of the voltage regulating winding connected to the circuit is the same as the polarity of the main winding, and the circuit can perform positive voltage regulation; when the polarity conversion switch is in the lower on state, the polarity of the voltage regulating winding connected to the circuit is opposite to the main winding, and the circuit can perform reverse voltage regulation.

[0027] During the positive voltage regulation process or the reverse voltage regulation process, the voltage regulating winding connected to the circuit can be adjusted to correspond to different gears by selecting to close the on-off switch of any voltage regulating branch separately.

[0028] When the on-off switch of any non-directly connected voltage regulating branch is in a closed state and the on-off switch of the transition switching unit is also in an on state, the voltage regulating circuit is in a normal operating state of the corresponding gear. This state is defined as the normal operating state of the non-directly connected circuit.

[0029] The on-off switch of the direct-connected voltage regulating branch is in a closed state, and the on-off switch of the transition switching unit is in an open state. At this time, the voltage regulating circuit is in a normal operating state of the corresponding gear. This state is defined as the normal working state of the direct-connected circuit.

[0030] From the perspective of circuit structure, in the technical solution of the present invention, one voltage regulating branch is a direct-connected voltage regulating branch, and the adjacent voltage regulating branch must be a non-direct-connected voltage regulating branch. In the multi-speed transformer voltage regulating circuit under this solution, each voltage regulating branch must be connected in this alternating form.

[0031] In the voltage regulating circuit under this technical solution, the so-called gear switching is to switch from the normal working state of one voltage regulating branch to the normal working state of another adjacent voltage regulating branch, either from the normal working state of the directly connected voltage regulating branch to the normal working state of the indirect connected voltage regulating branch, or from the normal working state of the indirect connected voltage regulating branch to the normal working state of the directly connected voltage regulating branch.

[0032] From the circuit structure point of view, as long as the on-off switch of the transition switching unit is in the off state, the transition resistor is always connected in series between two adjacent voltage regulating branches, which ensures that when the two adjacent voltage regulating branches are in the on state at the same time, the circuit will not be short-circuited, allowing the two voltage regulating branches to be energized at the same time, which ensures that the power supply will not be interrupted during the voltage regulation process.

[0033] Therefore, as long as the on-off switch in the transition switching unit is in the off state, voltage regulation can begin.

[0034] If it is switched from the normal working state of the direct-connected voltage regulating branch to the normal working state of the non-direct-connected voltage regulating branch, since the direct-connected voltage regulating branch is in the normal working state, the on-off switch of the transition switching unit is already in the off state at this time. Therefore, just close the on-off switch of the corresponding non-direct-connected voltage regulating branch, then open the on-off switch of the corresponding direct-connected voltage regulating branch, and then connect the on-off switch of the transition switching unit, so as to complete a gear switching.

[0035] If the process is switched from the normal working state of the non-direct-connected voltage regulating branch to the normal working state of the direct-connected voltage regulating branch, since the non-direct-connected branch is in the normal working state and the on-off switch of the transition switching unit is in the on state, the on-off switch of the transition switching unit must be disconnected first, and then the on-off switch of the corresponding direct-connected voltage regulating branch must be closed, and then the on-off switch of the corresponding non-direct-connected branch must be disconnected, thus completing one gear shift.

[0036] Therefore, the technical solution of the present invention is not unique in the connection mode, as long as each voltage regulating branch satisfies the direct connection and indirect connection alternating mode, the same technical effect can be achieved. The above two connection modes can be regarded as two preferred implementation modes under the same invention.

[0037] Therefore, when the transformer designed by the present invention is used, the on-off switch in the transition switching unit is only opened or closed once each time the gear is switched. The on-off switch in the transition switching unit is opened and closed once only when the gear is switched twice in succession. However, in the prior art, the vacuum interrupter of the main circuit transition circuit is opened and closed once each time the gear is switched.

[0038] It can be concluded that, compared with the prior art, the technical solution can reduce the number of opening and closing of the on-off switch by half under the premise of the same voltage regulation times. On the other hand, the technical solution of the present invention can always allow the voltage regulation branch of the previous gear to provide a transition voltage for the voltage regulation branch of the adjacent gear, so that the transition voltage can always change with the different voltage regulation gears.

[0039] In addition to the positive voltage regulation and reverse voltage regulation operations, there is also switching from positive voltage regulation to reverse voltage regulation, or from reverse voltage regulation to positive voltage regulation. During the switching process, the polarity conversion switch must be switched from the upper end to the lower end, or from the lower end to the upper end. During the switching process, each voltage regulation branch must be in a disconnected state and cannot provide a transition voltage for the voltage regulation circuit.

[0040] The rated voltage branch bypasses the polarity conversion switch and is directly connected between the main winding tap and the output end of the voltage regulation circuit. When the on-off switch of the rated voltage branch is closed, the rated voltage branch is in the on state, which can ensure that the circuit does not interrupt the voltage supply when switching between positive and negative voltage regulation.

[0041] Preferably, the transition switching unit on-off switch adopts a vacuum interrupter, so that the electric arc will not contaminate the transformer oil;

[0042] Preferably, the on-off switches connected in series with the voltage regulating branch and the rated voltage branch respectively adopt vacuum arc extinguishing chambers, so that the electric arc will not contaminate the transformer oil.

[0043] As another option, a first vacuum interrupter is connected in series on the line from the second input terminal to the output terminal in the transition switching unit, and a second vacuum interrupter is connected in series on the line from the first input terminal to the output terminal via the transition resistor, and at the same time, the on-off switches connected in series on the voltage regulating branch and the rated voltage branch are both ordinary on-off switches.

[0044] Further, as an option, a staggered parallel multi-speed transformer on-load voltage regulation circuit with polarity conversion includes a main winding, a polarity conversion switch, a voltage regulating winding, a transition switching unit, a rated voltage branch and three voltage regulating branches; the voltage regulating winding is composed of two sections of voltage regulating coils wound in the same direction connected end to end in sequence, the voltage regulating winding includes three taps, namely an upper tap, a middle tap and a lower tap, the input end of the main winding is connected to the input end of the voltage regulating circuit, and the output end of the main winding is connected to the common contact of the polarity conversion switch; the two independent contacts of the polarity conversion switch are respectively connected to the upper tap and the lower tap of the voltage regulating winding;

[0045] The transition switching unit includes two input terminals and one output terminal. A transition resistor and a transition unit vacuum interrupter connected in parallel are connected in series between the first input terminal of the transition switching unit and the output terminal of the transition switching unit. The second input terminal of the transition switching unit is directly connected to the output terminal of the transition switching unit. The second input terminal of the transition unit is both the output terminal of the transition switching unit and the output terminal of the voltage regulating circuit, and the three terminals are combined into one.

[0046] A vacuum interrupter is connected in series to each of the three voltage regulating branches and the rated voltage branch; the voltage regulating branch connected to the upper tap, the other end of which is connected to the first input end of the transition switching unit; the voltage regulating branch connected to the middle tap, the other end of which is connected to the second input end of the transition switching unit; the voltage regulating branch connected to the lower tap, the other end of which is connected to the first input end of the transition switching unit.

[0047] The rated voltage branch input end is connected to the main winding output end, and the rated voltage branch output end is connected to the voltage regulating circuit output end.

[0048] As another option, an on-load voltage regulating circuit of a staggered parallel multi-speed transformer with polarity conversion includes a main winding, a polarity conversion switch, a voltage regulating winding, a transition switching unit, a rated voltage branch and three voltage regulating branches; the voltage regulating winding is composed of two sections of voltage regulating coils wound in the same direction connected end to end in sequence, the voltage regulating winding includes three taps, namely, an upper tap, a middle tap and a lower tap, the input end of the main winding is connected to the input end of the voltage regulating circuit, and the output end of the main winding is connected to the common contact of the polarity conversion switch; two independent contacts of the polarity conversion switch are respectively connected to the upper tap and the lower tap of the voltage regulating winding;

[0049] The transition switching unit includes two input terminals and one output terminal. A transition resistor and a transition unit vacuum interrupter connected in parallel are connected in series between the first input terminal of the transition switching unit and the output terminal of the transition switching unit. The second input terminal of the transition switching unit is directly connected to the output terminal of the transition switching unit. The second input terminal of the transition unit is both the output terminal of the transition switching unit and the output terminal of the voltage regulating circuit, and the three terminals are combined into one.

[0050] The three voltage regulating branches are each connected in series with a vacuum interrupter on the rated voltage branch. The voltage regulating branch connected to the upper tap has the other end connected to the second input end of the transition switching unit; the voltage regulating branch connected to the middle tap has the other end connected to the first input end of the transition switching unit; the voltage regulating branch connected to the lower tap has the other end connected to the second input end of the transition switching unit;

[0051] The input end of the rated voltage branch is connected to the output end of the main winding, and the output end of the rated voltage branch is connected to the output end of the voltage regulating circuit.

[0052] In summary, the transformer designed according to the technical solution of the present invention has the advantages of long service life, small voltage fluctuation during transformation, high output voltage quality, halving the number of voltage regulating windings at the same gear, and low manufacturing cost.

[0053] In the present invention, the input terminal and the output terminal are defined to clearly describe the connection relationship between the various components of the circuit, wherein "input" and "output" are only used to distinguish different connection terminals and do not represent the flow or transmission direction of current or signal. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] Figure 1 The invention discloses a five-speed on-load forward and reverse voltage regulation circuit principle diagram using the technical solution of the invention.

[0055] Figure 2 The invention discloses a principle diagram of a five-speed on-load positive and negative voltage regulating circuit in another connection mode using the technical solution of the invention. DETAILED DESCRIPTION

[0056] The structural features and working principle of the positive and negative voltage regulating circuit of the present invention are further described below in conjunction with the accompanying drawings.

[0057] See also Figure 1 Shown is a schematic diagram of a five-speed transformer voltage regulation circuit under the technical solution in this aspect, which consists of a main winding, a voltage regulating winding, a rated voltage branch, a transition switching unit, and three voltage regulating branches.

[0058] The transition switching unit comprises a first input terminal T1, a second input terminal T2, an output terminal Xb, and a vacuum interrupter D0 connected in series between the first input terminal T1 and the output terminal Xb and a transition resistor R in parallel.

[0059] The first voltage regulating coil L1 and the second voltage regulating coil L2 are connected end to end to form a voltage regulating winding. A voltage regulating winding tap is provided at each end of the voltage regulating coil, wherein adjacent voltage regulating coil ends share a voltage regulating winding tap. The two voltage regulating coils are provided with three voltage regulating winding taps in total, namely, an upper end tap X1, a middle end tap X2, and a lower end tap X3.

[0060] The common contact of the polarity conversion switch KaKb is connected to the main winding output terminal Xa, and the two independent contacts of the polarity conversion switch are respectively connected to the upper tap X1 and the lower tap X3 of the voltage regulating winding.

[0061] On-off switch D1, on-off switch D2, on-off switch D3 and on-off switch Ke are all vacuum interrupters.

[0062] One end of the on-off switch D1 is connected to the tap X1 at the upper end of the voltage regulating winding, and the other end is connected to the second input end T2 of the transition switching unit, and exists as a voltage regulating branch.

[0063] One end of the on-off switch D2 is connected to the middle tap X2 of the voltage regulating winding, and the other end is connected to the first input terminal T1 of the transition switching unit, and is connected to the output terminal Xb of the voltage regulating circuit through the parallel structure of the vacuum interrupter D0 and the resistor R, existing as a voltage regulating branch.

[0064] One end of the on-off switch D3 is connected to the tap X3 at the lower end of the voltage regulating winding, and the other end is connected to the second input end T2 of the transition switching unit, and exists as a voltage regulating branch.

[0065] The rated voltage branch is connected in series with an on-off switch Ke, one end of the rated voltage branch is connected to the main winding output terminal Xa, and the other end is connected to the second input terminal T2 of the transition switching unit.

[0066] The correspondence between the combination states of the polarity conversion switch, each on-off switch and each gear position of the voltage regulation circuit is as follows:

[0067] 1st gear: Ka closes D3, closes D0, disconnects the voltage regulating windings L1 and L2, and both are connected to the circuit

[0068] 2nd gear: Ka is on, D2 is on, DO is on, and the voltage regulating winding L1 is connected to the circuit

[0069] 3rd gear: Ka closes D1 and D0, disconnects the voltage regulating windings L1 and L2, and neither is connected to the circuit

[0070] 3rd gear: Kb is on, D3 is on, D0 is off, and the voltage regulating windings L1 and L2 are not connected to the circuit

[0071] 4th gear: Kb is on, D2 is on, D0 is on, and the voltage regulating winding L2 is reversely connected to the circuit

[0072] 5th gear: Kb is closed, D1 is closed, D0 is disconnected, and the voltage regulating windings L1 and L2 are reversely connected to the circuit

[0073] The voltage regulation process is as follows:

[0074] In the first gear, the polarity conversion switch Ka terminal is in the on state, the on-off switch D3 is in the closed state, the transition switching unit vacuum interrupter D0 is in the off state, and the voltage regulating windings L1 and L2 are both positively connected to the circuit.

[0075] When switching from the first gear to the second gear, first close the on-off switch D2, the first gear and the second gear circuits are connected together, and the transition resistor R protects the circuit from short circuit. Then turn off the on-off switch D1, and the first gear circuit is in the disconnected state. Then close the vacuum interrupter D0, and the circuit completes the switch from the first gear to the second gear.

[0076] When switching from the second gear to the third gear, first disconnect the transition switching unit vacuum interrupter D0, then close the on-off switch D3, and then disconnect the on-off switch D2, and the circuit completes the switching from the second gear to the third gear.

[0077] When switching from the third gear to the fourth gear, the switch from positive voltage regulation to reverse voltage regulation must be completed first. The on-off switch Ke must be closed first, and the rated voltage branch is in the on state. Then the on-off switch D1 is disconnected, and the polarity conversion switch KaKb is in the power-off state. In this state, the polarity conversion switch is switched from the Ka end to the Kb end. Then the on-off switch D3 is closed, and the on-off switch Ke is disconnected. The switch from positive voltage regulation to reverse voltage regulation is completed, and the circuit is always in the third gear during this period.

[0078] When switching from the third gear to the fourth gear, the on-off switch D2 is closed, the on-off switch D3 is opened, and then the transition switching unit vacuum interrupter D0 is closed, and the circuit completes the switching from the third gear to the fourth gear.

[0079] When switching from the fourth gear to the fifth gear, first disconnect the transition switching unit vacuum interrupter D0, then close the on-off switch D1, and then disconnect the on-off switch D2, and the circuit completes the switching from the fourth gear to the fifth gear.

[0080] The five-speed voltage regulation circuit designed by the prior art requires four voltage regulation windings, while the five-speed circuit designed by the present invention only requires two voltage regulation windings, which reduces the use of voltage regulation windings by half and reduces the corresponding production cost. At the same time, the transition voltage of the circuit designed in the voltage regulation process changes with the voltage regulation gear, the voltage fluctuation is small, and there will be no problem of jump gear voltage regulation; the prior art needs to complete the voltage regulation process from one gear to five gears four times, and the main circuit and the rated voltage branch vacuum interrupter must be closed four times and opened four times. With the technical solution of the present invention, the vacuum interrupter with the highest switching frequency in the circuit only needs to be closed twice and opened twice, which reduces the number of switching times by half, greatly improving the effective use of the corresponding transformer.

[0081] The five-speed on-load forward and reverse voltage regulating transformer designed by the voltage regulating method of the present invention has the advantages of low cost, long service life and high voltage quality.

[0082] See also Figure 2 Shown is another schematic diagram of a five-speed transformer voltage regulation circuit under the technical solution in this aspect, which consists of a main winding, a voltage regulating winding, a rated voltage branch, a transition switching unit, and three voltage regulating branches.

[0083] The transition switching unit comprises a first input terminal T1, a second input terminal T2, an output terminal Xb, a vacuum interrupter D0 connected in series between the first input terminal T1 and the output terminal Xb, and a transition resistor R in parallel.

[0084] The first voltage regulating coil L1 and the second voltage regulating coil L2 are connected end to end to form a voltage regulating winding. A voltage regulating winding tap is provided at each end of the voltage regulating coil, wherein adjacent voltage regulating coil ends share a voltage regulating winding tap. The two voltage regulating coils are provided with three voltage regulating winding taps in total, namely, an upper end tap X1, a middle end tap X2, and a lower end tap X3.

[0085] The common contact of the polarity conversion switch KaKb is connected to the main winding output terminal Xa, and the two independent contacts of the polarity conversion switch are respectively connected to the upper tap X1 and the lower tap X3 of the voltage regulating winding.

[0086] On-off switch D1, on-off switch D2, on-off switch D3 and on-off switch Ke are all vacuum interrupters.

[0087] One end of the on-off switch D1 is connected to the tap X1 at the upper end of the voltage regulating winding, and the other end is connected to the first input end T1 of the transition switching unit, and is connected to the output end Xb of the voltage regulating circuit through the parallel structure of the vacuum interrupter D0 and the resistor R, existing as a voltage regulating branch.

[0088] One end of the on-off switch D2 is connected to the middle tap X2 of the voltage regulating winding, and the other end is connected to the second input end T2 of the transition switching unit, and exists as a voltage regulating branch.

[0089] One end of the on-off switch D3 is connected to the tap X3 at the lower end of the voltage regulating winding, and the other end is connected to the first input end T1 of the transition switching unit, and is connected to the output end Xb of the voltage regulating circuit through the parallel structure of the vacuum interrupter D0 and the resistor R, existing as a voltage regulating branch.

[0090] The rated voltage branch is connected in series with an on-off switch Ke, one end of the rated voltage branch is connected to the main winding output terminal Xa, and the other end is connected to the second input terminal T2 of the transition switching unit.

[0091] The correspondence between the combination status of the polarity conversion switch, the on-off switches of each branch and the various gears of the voltage regulation circuit is as follows:

[0092] 1st gear: Ka is on, D3 is on, D0 is on, and the voltage regulating windings L1 and L2 are both connected to the circuit

[0093] 2nd gear: Ka closes D2, closes DO, disconnects the voltage regulating winding L1, and connects to the positive circuit

[0094] 3rd gear: Ka is on, D1 is on, D0 is on, and the voltage regulating windings L1 and L2 are not connected to the circuit

[0095] 3rd gear: Kb is on, D3 is on, D0 is on, and the voltage regulating windings L1 and L2 are not connected to the circuit

[0096] 4th gear: Kb closes D2 closes D0 and disconnects the voltage regulating winding L2, reversely connects to the circuit

[0097] 5th gear: Kb is on, D1 is on, D0 is on, and the voltage regulating windings L1 and L2 are reversely connected to the circuit

[0098] The voltage regulation process is as follows:

[0099] In the first gear, the polarity conversion switch Ka terminal is in the on state, the on-off switch D3 is in the closed state, the transition switching unit vacuum interrupter D0 is in the closed state, and the voltage regulating windings L1 and L2 are both positively connected to the circuit.

[0100] When switching from the first gear to the second gear, first disconnect the transition switching unit vacuum interrupter D0, then close the on-off switch D2, the first gear and the second gear circuits are connected together, and the transition resistor R protects the circuit from short circuit. Then disconnect the on-off switch D3, and the first gear circuit is in the disconnected state. Then disconnect the vacuum interrupter D0, and the circuit completes the switch from the first gear to the second gear.

[0101] When switching from the second gear to the third gear, first close the on-off switch D1, then open the on-off switch D2, and then close the transition switching unit vacuum interrupter D0, and the circuit completes the switching from the second gear to the third gear.

[0102] When switching from the third gear to the fourth gear, the switch from positive voltage regulation to reverse voltage regulation must be completed first. The on-off switch Ke must be closed first, and the rated voltage branch is in the on state. Then the on-off switch D1 is disconnected, and the polarity conversion switch KaKb is in the power-off state. In this state, the polarity conversion switch is switched on. Switch the polarity conversion switch from the Ka end to the Kb end. Then close the on-off switch D3 and disconnect the on-off switch Ke. Complete the switch from positive voltage regulation to reverse voltage regulation. During this period, the circuit is always in the third gear.

[0103] When switching from the third gear to the fourth gear, first disconnect the vacuum interrupter D of the transition switching unit, then close the on-off switch D2, and disconnect the on-off switch D3, and the circuit completes the switching from the third gear to the fourth gear.

[0104] When switching from the fourth gear to the fifth gear, the on-off switch D1 is closed, then the on-off switch D2 is opened, and then the transition switching unit vacuum interrupter D0 is closed, and the circuit completes the switching from the fourth gear to the fifth gear.

[0105] Figure 2 Circuit and Figure 1 Compared with the circuit, although the connection method is different, it has the same technical effect. Compared with the existing technology, it also achieves the purpose of reducing the use of voltage regulating windings by half, reducing the corresponding production cost; at the same time, the transition voltage of the circuit designed in the voltage regulation process changes with the voltage regulation gear, and there is no jump gear voltage regulation problem; the vacuum interrupter in the circuit has a low switching frequency.

Claims

1. An on-load voltage regulating circuit of a staggered parallel multi-speed transformer with polarity conversion, comprising a main winding, a polarity conversion switch, a voltage regulating winding, a transition switching unit, a rated voltage branch and a plurality of voltage regulating branches; It is characterized in that The voltage regulating winding is composed of N coils wound in the same direction connected end to end in sequence, the voltage regulating winding includes two end taps and N-1 middle taps, the main winding input end is connected to the input end of the voltage regulating circuit, and the main winding output end is connected to the common contact of the polarity conversion switch; the two independent contacts of the polarity conversion switch are respectively connected to the two end taps of the voltage regulating winding; The transition switching unit comprises two input ends and one output end, and the output end of the transition switching unit serves as the output end of the voltage regulating circuit; a transition resistor and an on-off switch of the transition switching unit connected in parallel are connected in series between the first input end of the transition switching unit and the output end of the transition switching unit, and the second input end of the transition switching unit is connected to the output end of the transition switching unit; One end of each of the voltage regulating branches is connected to two end taps and each middle tap of the voltage regulating winding respectively; the other end of each of the voltage regulating branches is connected in parallel to form two groups adjacently and alternately, and is connected to two input ends of the transition switching unit respectively; Each voltage regulating branch and the rated voltage branch are respectively connected in series with an on-off switch; An on-off switch is connected in series on the rated voltage branch, one end of the rated voltage branch is connected to the output end of the main winding; the other end is connected to any end of the transition switching unit; The transition switching unit is composed of a transition resistor and an on-off switch connected in parallel, a first input end of the transition switching unit is connected to a first end of the transition resistor and a first end of the on-off switch, a second input end of the transition switching unit also serves as an output end of the transition switching unit, and an output end of the transition switching unit is connected to a second end of the transition resistor and a second end of the on-off switch; A first vacuum interrupter is connected in series on the line from the second input end to the output end in the transition switching unit, a second vacuum interrupter is connected in series on the line from the first input end to the output end via the transition resistor, and the on-off switches connected in series on the voltage regulating branch and the rated voltage branch are both ordinary on-off switches.

2. The on-load voltage regulation circuit of a staggered parallel multi-speed transformer with polarity conversion according to claim 1, characterized in that: One end of the rated voltage branch is connected to the output end of the main winding; the other end is connected to the output end of the transition switching unit.

3. The on-load voltage regulation circuit of a staggered parallel multi-speed transformer with polarity conversion according to claim 1, characterized in that: The on-off switches connected in series on the voltage regulating branch and the rated voltage branch can both adopt vacuum interrupters.

4. The on-load voltage regulation circuit of a staggered parallel multi-speed transformer with polarity conversion according to claim 1, characterized in that: The voltage regulating winding is composed of two sections of voltage regulating coils wound in the same direction connected end to end in sequence. The voltage regulating winding includes three taps, namely, an upper tap, a middle tap, and a lower tap. The input end of the main winding is connected to the input end of the voltage regulating circuit, and the output end of the main winding is connected to the common contact of the polarity conversion switch; the two independent contacts of the polarity conversion switch are respectively connected to the upper tap and the lower tap of the voltage regulating winding; each of the three voltage regulating branches and the rated voltage branch is connected in series with a vacuum interrupter; A voltage regulating branch connected to the upper tap, the other end of which is connected to the first input end of the transition switching unit; a voltage regulating branch connected to the middle tap, the other end of which is connected to the second input end of the transition switching unit; a voltage regulating branch connected to the lower tap, the other end of which is connected to the first input end of the transition switching unit; One end of the rated voltage branch is connected to the output end of the main winding; the other end is connected to the output end of the transition switching unit.

5. The on-load voltage regulation circuit of a staggered parallel multi-speed transformer with polarity conversion according to claim 1, characterized in that: The voltage regulating winding is composed of two sections of voltage regulating coils wound in the same direction connected end to end in sequence. The voltage regulating winding includes three taps, namely, an upper tap, a middle tap, and a lower tap. The input end of the main winding is connected to the input end of the voltage regulating circuit, and the output end of the main winding is connected to the common contact of the polarity conversion switch; the two independent contacts of the polarity conversion switch are respectively connected to the upper tap and the lower tap of the voltage regulating winding; each of the three voltage regulating branches and the rated voltage branch is connected in series with a vacuum interrupter; A voltage regulating branch connected to the upper tap, the other end of which is connected to the second input end of the transition switching unit; a voltage regulating branch connected to the middle tap, the other end of which is connected to the first input end of the transition switching unit; a voltage regulating branch connected to the lower tap, the other end of which is connected to the second input end of the transition switching unit; One end of the rated voltage branch is connected to the output end of the main winding; the other end is connected to the output end of the transition switching unit.

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