Flywheel energy storage arc-free switching contact adjusting device and method of on-load tap changing transformer

Abstract

The invention relates to a flywheel energy storage arc-free switching contact adjusting device and method of an on-load tap changing transformer. The flywheel energy storage arc-free switching contact adjusting device comprises a power supply; the transformer comprises a primary side and a secondary side, and the power supply is connected with the primary side of the transformer; the gating switch group is connected with the primary side of the transformer; the change-over switch is connected with the transformer gating switch group, and the power supply, the transformer, the transformer gating switch group and the change-over switch form a current path; the controlled source is connected with the change-over switch, the controlled source comprises a flywheel motor, in the switching-on process of the change-over switch, the flywheel motor provides a zero-voltage condition for the change-over switch, and electric arcs generated by on-off of the change-over switch are weakened by reducing current passing through when the change-over switch is switched off. Under the condition that the semiconductor device is conducted, the voltage output by the flywheel motor enables the voltage at the two ends of the on-load tap-changer to be controlled to be zero, zero-voltage closing is achieved, and therefore arc-free closing of the change-over switch is achieved.

Description

Technical Field

[0001] The invention relates to the technical field of transformer voltage regulation, and in particular to a flywheel energy storage arc-free switching contact regulating device and method for an on-load voltage regulating transformer. Background Art

[0002] As the scale of the power system continues to expand, the imbalance of power generation and consumption in the power grid, as well as the randomness of load fluctuations, will cause voltage deviation and fluctuations, and even exceed the voltage limit, causing safety hazards for equipment and endangering the stability of power system operation. As a key device in the power transmission and distribution system of the power grid, the 10kV dry-type on-load voltage regulating transformer will be used more and more frequently in the future power system. Therefore, it is necessary to continuously optimize and improve the on-load voltage regulating device.

[0003] As one of the important components of the on-load tap changer, the optimization of its performance is conducive to the on-load tap changer to play a better role in the power system. When the OLTC adjusts the control transformer to change the output voltage, arcing may occur, affecting the normal operation and service life of the on-load tap changer. Therefore, arc extinguishing is an important issue in the design and research of the on-load tap changer. A more effective arc extinguishing scheme is designed to improve the efficiency and speed of arc extinguishing, thereby ensuring the safe operation of the equipment and extending its life.

[0004] The appearance of electric arc will cause wear of the switch contacts and affect the service life of the transfer switch. Therefore, how to effectively eliminate the arc generated when the transfer switch is switched is the key to ensuring the safe and stable operation of the on-load voltage regulation device. Summary of the invention

[0005] The purpose of the present invention is to overcome the defects of the above-mentioned prior art and to provide a flywheel energy storage arc-free switching contact adjustment device and method for an on-load voltage-changing transformer, so as to solve or partially solve the problem of how to effectively eliminate the arc generated by the switching switch when switching to ensure the safe and stable operation of the on-load voltage-changing device.

[0006] The purpose of the present invention can be achieved by the following technical solutions:

[0007] One aspect of the present invention provides a flywheel energy storage arc-free switching contact adjustment device for an on-load voltage-changing transformer, comprising:

[0008] power supply;

[0009] A transformer, comprising a primary side and a secondary side, wherein the power supply is connected to the primary side of the transformer;

[0010] A transformer gating switch group connected to the primary side of the transformer;

[0011] A switching switch connected to the transformer gating switch group, wherein the power supply, the transformer, the transformer gating switch group and the switching switch form a current path;

[0012] A transition resistor and a transition branch switch are connected in parallel with the switching switch;

[0013] A controlled source is connected to the switching switch, and the controlled source includes a flywheel motor. During the closing process of the switching switch, the flywheel motor provides a zero voltage condition for the switching switch to be closed, and reduces the current passing through when the switching switch is disconnected during the switching contact process, thereby weakening the arc generated by the switching of the switching switch.

[0014] As a preferred technical solution, the transformer gating switch group includes multiple gating switches, including two of the switching switches, namely a first switching switch and a second switching switch. The multiple gating switches are divided into a first gating switch set and a second gating switch set. One end of each gating switch in the first gating switch set is connected to the primary side of the transformer, and the other end is connected to the first switching switch. One end of each gating switch in the second gating switch set is connected to the primary side of the transformer, and the other end is connected to the second switching switch.

[0015] As a preferred technical solution, the controlled source further comprises:

[0016] An AC / DC converter connected to the flywheel motor;

[0017] A DC / AC converter connected to the AC / DC converter;

[0018] A first semiconductor unit, one end of which is connected to the DC / AC converter, and the other end of which is connected to the first switch;

[0019] A second semiconductor unit has one end connected to the DC / AC converter and the other end connected to the second switch.

[0020] As a preferred technical solution, a mechanical switch is further connected in series with respect to the branch where any one of the first semiconductor unit and the second semiconductor unit is located.

[0021] As a preferred technical solution, the semiconductor unit includes:

[0022] The thyristor pairs arranged in anti-parallel are respectively connected to the corresponding switching switches and the DC / AC converter;

[0023] A snubber is connected in parallel with the thyristor pair.

[0024] As a preferred technical solution, it also includes:

[0025] A load is connected to the secondary side of the transformer.

[0026] As a preferred technical solution, the switching switch is a mechanical switching switch, and the switching switch in the transformer switching switch group is an on-load tap changer selector.

[0027] As a preferred technical solution, the multiple selection switches in the transformer selection switch group correspond to (1±2×2.5%) U N Voltage level, where U N is the rated voltage of the transformer.

[0028] As a preferred technical solution, the flywheel rotor of the flywheel motor is connected to the motor rotor via a bearing, and the flywheel is driven to rotate via the motor rotor.

[0029] Another aspect of the present invention provides a method for adjusting the flywheel energy storage arc-free switching contact of an on-load voltage-changing transformer, which is applied to the flywheel energy storage arc-free switching contact adjusting device of the on-load voltage-changing transformer, and the adjustment method comprises the following steps:

[0030] Step S1, obtaining a load voltage value;

[0031] Step S2, determining whether the load voltage fluctuation range exceeds a preset limit, if so, executing step S3, if not, executing step S1;

[0032] Step S3, determining whether the load voltage value exceeds the voltage upper limit, if so, executing step S4, if not, executing step S7;

[0033] Step S4, determine whether the tap is adjusted to the lower limit, if yes, execute step S1, if no, execute step S5;

[0034] Step S5, determine whether the superior has taken action, if not, execute step S1, if yes, execute step S6;

[0035] Step S6, the selector moves downward, triggering the thyristor corresponding to the switch on the side to be closed to turn on, realizing arc-free closing of the transition branch switch, adjusting the controlled source to achieve zero voltage during the closing of the transition branch switch, disconnecting the switch on the opposite side of the side to be closed, and then controlling the controlled source to achieve arc-free closing of the switch on the side to be closed, adjusting the controlled source to achieve zero voltage during the closing of the switch, turning off the thyristor, updating the load voltage value and judging whether the load voltage value exceeds the voltage upper limit, if yes, executing step S4, if not, executing step S1;

[0036] Step S7, determine whether the tap is adjusted to the upper limit, if so, execute step S1, if not, execute step S8;

[0037] Step S8, determine whether the superior has taken action, if not, execute step S1, if yes, execute step S9;

[0038] Step S9, the selector moves upward, triggering the thyristor corresponding to the switching switch on the side to be closed to turn on, realizing arc-free closing of the transition branch switch, and during the closing period of the transition branch switch, the controlled source is adjusted to achieve zero voltage, and the switching switch on the opposite side to be closed is disconnected, and then the controlled source is controlled to achieve arc-free closing of the switching switch on the side to be closed. During the closing period of the switching switch, the controlled source is adjusted to achieve zero voltage, the thyristor is turned off, the load voltage value is updated and it is determined whether the load voltage value is lower than the lower limit of the voltage value. If so, execute step S7, if not, execute step S1.

[0039] Compared with the prior art, the present invention has at least the following beneficial effects:

[0040] The present invention takes into account the characteristics of the flywheel rotor, such as large mass, large inertia, impact tolerance and fast response speed of the flywheel, and uses the flywheel motor as a controlled source for arc-free switching of the transformer on-load voltage regulating device. It can achieve rapid response when the switching switch is actuated, and quickly adjust the voltage across the switching switch to less than a certain threshold or to zero. At the same time, the flywheel is not easily affected by shocks such as abnormal conditions or faults in the power system. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 Schematic diagram of a flywheel energy storage arc-free switching contact adjustment device for an on-load voltage-changing transformer in an embodiment;

[0042] Figure 2 is a conduction timing diagram of the switch and thyristor of the device in the embodiment;

[0043] Figure 3 It is a complete schematic diagram of on-load voltage regulation with the addition of controlled source;

[0044] Figure 4 It is a schematic diagram of a controlled source control system;

[0045] Figure 5 It is a schematic diagram of simulation results of the voltages V_SL and V_SR on both sides of the switching switch;

[0046] Figure 6 (a)-(c) and (d)-(f) are waveforms of the current through the switch and the voltage across the switch when the conventional mechanical OLTC is switched at different times (maximum current, middle current, zero point) under inductive loads with different power factors (0.6 and 0.8);

[0047] Figure 7It is a schematic diagram of the current flowing through the switch and the voltage waveform at both ends of the switch at different times under a capacitive load with a power factor of 0.6 of a conventional mechanical OLTC;

[0048] Figure 8 This is an enlarged view of the load current and load voltage waveforms of the OLTC switching with the controlled source device added;

[0049] Fig. 9 It is a schematic diagram of load voltage waveform;

[0050] Fig.10 Switching flow chart for on-load voltage regulator with active current diversion device;

[0051] Fig.11 A schematic diagram of an electronic device. DETAILED DESCRIPTION

[0052] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0053] Example 1

[0054] The appearance of electric arc will cause wear of the switch contacts and affect the service life of the transfer switch. How to effectively eliminate the arc generated when the transfer switch is switched is the key to ensuring the safe and stable operation of the on-load voltage regulator.

[0055] Regarding the voltage across the switch, when the switch is closed, due to the small distance between the switch contacts, when the voltage between the switch contacts is too high, the electric field strength is very large, and electric breakdown will occur between the contacts, generating an arc. Therefore, before the contacts are closed, the voltage across the switch is made less than a certain threshold or even zero to eliminate the conditions for arc generation, avoid electric breakdown, and no arc will be generated when the contacts are closed.

[0056] Regarding the current passing through the switch, from one perspective, when the switch is disconnected, an arc is inevitably generated. The generation of the arc is the result of the dissipation of energy stored in the circuit. The energy E storage formula is as follows:

[0057]

[0058] Among them, L is the inductance element connected in the circuit or the parasitic inductance generated, and I is the current flowing in the circuit.

[0059] It can be seen from formula (1) that the energy E stored in the circuit is related to the inductance L in the circuit and the current I flowing through it. Therefore, reducing the current flowing through the switch before the contacts separate can reduce the energy storage in the circuit and weaken the arc generated by the contact opening.

[0060] From another perspective of current, the short gap spark resistance model proposed by Toepler is applied to the impact arc discharge process, and its mathematical model is:

[0061]

[0062] Among them, R t is the arc resistance; K τ is the model constant; d is the gap distance; τ is the arc breakdown time; i is the instantaneous value of current.

[0063] Before the switch is separated, the load current is normally carried, and the load current I AC The sizes are as follows:

[0064]

[0065] Among them, U AC is the power supply voltage; is the initial phase of voltage; R is the sum of the primary and secondary windings of the transformer and the load resistance after calculation; L is the sum of the primary and secondary windings of the transformer and the load inductance after calculation; ω is the angular frequency.

[0066] If the switch is opened when it is normally carrying current, a switch arc will be generated. Substituting equation (3) into equation (2) can obtain the arc generated by the switch opening at this time. If the current passing through the switch is reduced before the switch is opened, according to equation (2), the smaller the current i, the smaller the arc resistance R t The larger the value, the better it is for suppressing the arc generated when the switch is disconnected.

[0067] In this embodiment, in order to effectively eliminate the problem of arc generated by the switching switch during switching, a controlled source with a flywheel motor is introduced to actively provide a zero voltage condition for the switching switch during the closing process, reduce the current passing through when the switching switch is disconnected, weaken the arc generated by the switching of the switching switch, and ensure the safety and stability of the operation of the on-load voltage regulation device.

[0068] See also Figure 1 This embodiment provides a flywheel energy storage arc-free switching contact adjustment device for an on-load voltage-changing transformer, comprising:

[0069] Current path, the current path is from the power supply U AC Start, pass the transformer, transformer selection switches S1~S5, and switch S L or S R, then return to the power supply U AC access;

[0070] Controlled source, the controlled source includes a flywheel motor G with a flywheel rotor, an AC / DC and DC / AC converter, and a semiconductor device and

[0071] load.

[0072] Specifically, the electrical device in which the controlled source with the flywheel motor is used to realize arc-free closure of the transformer on-load tap changer can be roughly divided into two parts: the transformer on-load tap module and the semiconductor module.

[0073] The on-load tapping module includes the transformer body, on-load tapping switch selectors S1 to S5, and mechanical switching switch S L and S R , transition branch. The load tap selector switches S1~S5 correspond to (1±2×2.5%)U N The voltage level of the switch S L and S R Before you start, select the gear. Mechanical switch S L and S R Located in the current path, used to switch the load current in the current path and carry the load current I AC The transition resistor in the transition branch is used to prevent short circuit faults between taps.

[0074] The semiconductor module has two pairs of anti-parallel thyristors. and Switch S on both sides L and S R Connection for introducing a controlled source into a switching switch; in semiconductor devices and Each branch has a mechanical switch S T1 and S T2 In series with semiconductor elements, mechanical switch S T1 and S T2 Used to limit short-circuit current and prevent semiconductor devices and When the transformer is turned on incorrectly or fails, it will cause a short circuit between the transformer taps and damage the transformer device. The thyristor pair includes a forward thyristor and and an anti-parallel reverse thyristor and Each of them passes a sinusoidal half wave, so that the anti-parallel thyristor pair passes a sinusoidal alternating current normally. and As an AC switch, the controlled source is connected to the switch SL or S R One side. It also includes a buffer, which is connected to the thyristor and Connected in parallel, the buffer includes a resistor R T and a capacitor C T , when the thyristor stops conducting, the buffer is used to limit the voltage V applied to the thyristor T1 or V T2 rate of change to prevent the thyristor from being triggered again.

[0075] The converter includes a controlled rectifier AC / DC, an inverter DC / AC and a DC capacitor. The controlled rectifier AC / DC is a fully controlled rectifier device composed of six fully controllable power switching devices IGBT, with the connected switching switch S L or S R The voltage at one end is zero, and a PWM control signal is generated. The conduction sequence and switching frequency of the IGBT components in the rectifier are controlled by the control signal, and the PWM duty cycle is changed to rectify the AC output of the flywheel motor into DC and input to the capacitor; the inverter is a three-phase bridge inverter composed of six diodes, which inverts the DC on the capacitor into AC and applies it to the switching switch S L or S R one end of the switch so that the voltage across the switch is zero.

[0076] This device is configured so that when the semiconductor device or When turned on, the controlled source is connected to the switching switch S L or S R At one end, the output voltage of the controlled source is controlled to make the switch S to be closed L or S R and transition branch switch S L1 or S R1 The voltage across the two ends is kept below a certain threshold or even zero, so that the switch S L or S R and transition branch switch S L1 or S R1 Close under zero voltage conditions to achieve arc-free closing of the switch.

[0077] When the transition branch switch S L1 or S R1 After closing, the current paths on both sides are in the on state, each carrying nearly half of the normal load current. r or S LWhen disconnected, the reduction of the carrying current also reduces the arc generated when it is disconnected, reducing the wear of the switch contacts, extending the service life of the switch and reducing maintenance costs.

[0078] In this device, considering that the flywheel rotor of the flywheel motor is connected to the motor rotor through a bearing, the flywheel is driven to rotate by the rotation of the motor rotor. Due to the advantages of the flywheel rotor such as large mass, large inertia, impact resistance and fast flywheel response speed, it is used for arc-free switching of the transformer on-load voltage regulating device. It can achieve rapid response when the switching switch is actuated, and quickly adjust the voltage at both ends of the switching switch to less than a certain threshold or zero. At the same time, when facing the impact of abnormal conditions or faults in the power system, the flywheel is not easily affected.

[0079] The action steps of the transformer on-load voltage regulating device with a controlled source are as follows: monitor the load voltage, and when the load voltage is detected to exceed the set voltage threshold, select the corresponding upward or downward movement of the switch, connect the controlled source, and close the transition branch switch corresponding to the new voltage level without arcing under the action of the controlled source, and then disconnect the switching switch on the other side at a relatively small current, and then close the switching switch on the new voltage level side to weaken the on-off arc of the switching switch, and then continue to monitor the load voltage, and cycle the above gear switching until the load voltage returns to the normal range.

[0080] The following is a specific implementation of the adjustment device of this embodiment.

[0081] like Figure 1 The diagram is a schematic diagram of an on-load voltage regulator with a controlled source having a flywheel motor. The device includes a power source U AC , transformer and its on-load tapping device selection switch S1 ~ S5, on-load tapping device switch S L and S R 、Semiconductor components Controlled sources and loads.

[0082] The current path includes a selection switch and a switching switch. The current in the current path flows from the power supply U AC Starting from the transformer, the on-load voltage regulator selector switches S1~S5, and the switching switch S L and S R Back to Power U AC ; The controlled source device includes a semiconductor element Controlled source that triggers semiconductor components or The controlled source is connected to the switch S L or S R On one side, the controlled source is operated to change its output voltage so that the switch S L or S R and transition branch switch SL1 or S R1 The voltage across the two ends is less than a certain threshold or zero, thus switching the switch S L or S R and transition branch switch S L1 or S R1 No arc closure.

[0083] Depend on Figure 1 As shown in the figure, the transformer on-load tapping device includes a selector switch and a transfer switch. The odd-numbered selector switch positions are connected to the left transfer switch S L Connection, even-numbered selector switch positions and right-hand toggle switch S R When the selector switch is switched, the left and right switch S L and S R Realize interactive on-off; select switches S1~S5 without interrupting and connecting the load current I AC , which is switched by switch S L and S R Responsible for completion.

[0084] There is also resistance between the actual switch contacts. The resistance generated by the switch contacts can be calculated using the empirical formula: Among them, F (N) is the contact pressure, R (mΩ) is the contact resistance, m is a coefficient related to the contact form, usually 0.5 to 1, K is a coefficient related to the contact material, surface condition, contact mode, etc., K = 0.06 for Ag-Ag, K = 0.98 for Al-Cu. As the contact pressure increases, the effective contact area of ​​the contact point is increased and the influence of the surface film on the contact resistance is suppressed to the maximum extent, so that the resistance of the contact is reduced.

[0085] Thyristor Pair or It is necessary to switch the switch S L , S R Before closing) triggers conduction, and must be able to carry the flywheel motor for a short time to provide current to the switch S L or S R After closing, the thyristor pair can be triggered to open.

[0086] Figure 2 The timing diagram of the on-off of the switch and thyristor of each on-load voltage regulator is given, where 1 represents that the switch or thyristor is in the on state, 0 represents that the switch or thyristor is in the off state, and the intermediate state represents that the switch is in the transition state and is not clearly in the closed state or the open state.

[0087] Two additional mechanical tap switches are required on the path where the semiconductor device is located, such as Figure 3 The mechanical switch S shownT1 and S T2 , respectively with the left and right thyristor pairs and They are connected in series and are in a closed state during normal operation. This prevents the thyristors on both sides from being turned on at the same time when the thyristor fails or fails, which would cause a short circuit between the taps and damage the transformer device.

[0088] The buffer (capacitor C T and resistor R T ) is used to limit the voltage V applied to the thyristor T1 and V T2 to prevent the thyristor from turning back on after being turned off.

[0089] The schematic diagram of the controlled source is as follows Figure 3 As shown, the flywheel rotor is connected to the rotor of the motor through a bearing, and the rotation of the motor rotor drives the flywheel rotor to rotate. The flywheel rotor has the advantages of large mass, large inertia, impact resistance and fast response speed, and is applied to the controlled source to provide arc-free switching conditions for the transformer on-load voltage regulation device. In addition, during the operation of the switching switch, the controlled source can achieve rapid response due to the presence of the flywheel motor, and quickly adjust the voltage at both ends of the switching switch to below a certain threshold or to zero, which is beneficial to the arc-free switching of the switching switch. At the same time, when facing the impact of abnormal conditions or faults in the power system, the flywheel is not easily affected due to its inherent characteristics.

[0090] The converter in the controlled source mainly includes a controlled rectifier AC / DC, an inverter DC / AC and a DC capacitor. The controlled rectifier AC / DC is a fully controllable rectifier device composed of six fully controllable power switching devices IGBT. It generates a PWM control signal with the goal of making the voltage across the connected switch zero. The control signal is used to control the conduction sequence and switching frequency of the IGBT elements in the rectifier device, change the PWM duty cycle, and rectify the AC power output by the flywheel motor into DC power and input it into the capacitor; the inverter is a three-phase bridge inverter device composed of six diodes, which inverts the DC power on the capacitor into AC power and applies it to one end of the switching switch, so that the voltage across the switching switch is zero.

[0091] The specific control principle in the controlled source is as follows Figure 4 As shown in the figure, the scheme is based on the reference voltage (zero voltage) and the measured terminal voltage (V a 、V b 、V c), when the measured voltage is inconsistent with the reference voltage, the error signal is used as the modulation signal to control the IGBT of the rectifier. By comparing the error signal between the triangular wave as the modulation wave and the sine wave to be modulated, the PWM duty cycle is changed, thereby changing the switching frequency and conduction time of the IGBT, thereby realizing the control of the controllable rectifier and achieving the control target.

[0092] In summary, the controlled source can achieve:

[0093] 1. Actively provide the switch with zero voltage before it is closed. Before the switch is closed, the voltage at both ends is not zero. The voltage is collected through a voltage transformer and injected into the control system of the controlled source to change the output of the controlled source to achieve the goal of zero voltage at both ends of the switch.

[0094] 2. During the closing of the transfer switch, the controlled source is dynamically controlled to achieve arc-free closing of the transfer switch.

[0095] The design adds a controlled source with a flywheel motor to achieve arc-free voltage regulation of the on-load voltage regulator, which is effective when the switch is closed. The idea of ​​introducing a controlled source with a flywheel motor in this design is not only applicable to this device, but also to other mechanical switching devices, and can also be extended to DC systems.

[0096] In order to verify the effectiveness of the designed controlled source in controlling the voltage, such as Figure 5 The figure shows the simulation result of the voltage across the switch with the controlled source added and its enlarged figure. It can be seen from the figure that when the system has two load fluctuations in opposite directions at 0.1s and 0.5s respectively, the on-load voltage regulator will perform two switching actions in opposite directions, that is, the switch switches from left to right and from right to left. Figure 5 It can be seen that when load fluctuations occur at 0.1s and 0.5s and voltage regulation is required, the controlled source is connected before and during the closing process of the switch to control the voltage V at both ends of the switch. SL and V SR is zero, which verifies the effectiveness of the model.

[0097] In order to verify the effectiveness of the designed controlled source device in arc extinguishing during OLTC switching, Figure 6(a)-(c) and (d)-(f) are the waveforms of the current through the switch and the voltage across the switch when the traditional mechanical OLTC switches at different times (maximum current, middle value, zero point) under inductive loads with different power factors (0.6 and 0.8). Comparing the waveforms of the current switching at different phases, it can be seen that the size of the switch arc generated by the OLTC is different when the current phases are switched. When the branch current is switched at zero point, no switch arc will be generated. As the current phase increases, that is, the branch current amplitude increases, the larger the switch arc generated, the more difficult it is to extinguish, and the more obvious the current transient process fluctuations. When switching at the peak point of the branch current, the transient process of the switching current is most obvious, and an arc is generated during switching, which is not conducive to the safe and stable operation of the power system. Comparing the OLTC switching waveforms under different power factors, it can be seen that when the load is inductive, the lower the load power factor, the larger the impedance angle, and the longer the load current and load voltage fluctuation time.

[0098] Figure 7 (a)-(c) are schematic diagrams of the current and voltage waveforms of the traditional mechanical OLTC switching through the switch at different times under a capacitive load with a power factor of 0.6. It can also be seen that when the capacitive current is large at the moment of switching, the switching arc is large, and when the capacitive current is switched near the zero point, the switching arc is small.

[0099] Depend on Figure 8 It can be seen that the OLTC with the controlled source device achieves zero voltage condition before the switching switch is closed due to the control of the controlled source. No arc will be generated during the switching process, and the load current and load voltage fluctuate smoothly. Therefore, the effectiveness of the model in arc extinguishing during the OLTC switching process is verified, and it will not affect the safe and stable operation of the power system.

[0100] Fig. 9 Figure 3 is a waveform diagram of the load voltage. The load voltage fluctuates in opposite directions at 0.1s and 0.5s, respectively, and the on-load voltage regulator switches to keep its voltage within the limit (for three-phase power supply of 10kV and below, the allowable voltage deviation is ±7% of the rated voltage). The load voltage fluctuates smoothly during the switching process, ensuring the safe and stable operation of the power system.

[0101] Example 2

[0102] Based on Example 1, see Fig.10 This embodiment provides a flywheel energy storage arc-free switching contact adjustment method for an on-load voltage-regulating transformer, which is applied to the flywheel energy storage arc-free switching contact adjustment device for an on-load voltage-regulating transformer as described above. Fig.10The switching flow chart of the on-load voltage regulator with a controlled source device is shown in the figure. The voltage transformer collects the load voltage and monitors the load voltage. If the load voltage exceeds the upper and lower limits of the voltage range, the voltage is adjusted. The position of the tap is monitored first. If the tap position is at the upper limit, the voltage cannot be adjusted upward. If it is at the lower limit, the voltage cannot be adjusted downward. The voltage still does not meet the requirements. In addition to the above, the voltage can be adjusted. Ask the superior whether to act. After obtaining consent, start the voltage adjustment. Perform the switching process of the on-load tap changer with the controlled source added above. Achieve the "zero voltage" condition for the switch to be closed, achieve arc-free closure, and disconnect the switch on the opposite side. After the switching is completed, continue to monitor whether the load voltage is still over the limit. If so, select the switch to continue switching in the same direction until the load voltage meets the voltage fluctuation range. The switching is completed and the load voltage is monitored continuously.

[0103] Specifically, taking the switching of the selector switch from S1 to S2 as an example, the specific switching steps of the on-load voltage regulator with a controlled source are as follows:

[0104] 1. In the initial state, the on-load voltage regulator operates steadily at the voltage level where the transformer tap 1 is located. Select switch S1 and switch S L Both are closed to carry the load current.

[0105] 2. When t=t1, the selection switch S2 is closed, and the on-load voltage regulator is ready to start switching to the voltage level corresponding to the selection switch S2.

[0106] 3. When t=t2, the right thyristor is triggered Conductivity.

[0107] 4. At t = t3, the controlled source is controlled to actively make the right switch S R1 The voltage at both ends is controlled to be zero or close to zero, and the right thyristor The trigger gate current is removed, but it still conducts and carries the current provided by the controlled source.

[0108] 5. At t = t4, switch S R1 The voltage across the two ends is zero or less than a certain threshold, and the switch S R1 Trigger closing, during the closing process, dynamically control the controlled source to make the switch S R1 The voltage across both ends is always zero, which allows it to close without an arc under zero voltage conditions.

[0109] 6. t = t5, switch S R1 It is closed. At this time, a switch on each of the left and right branches is in the closed state. The two branches are connected in parallel, and each bears almost half of the load current.

[0110] 7. When t=t6, switch S on the left LDisconnect, because the two branches are connected in parallel, the load current carried by the switch on this side is reduced, so the arc of disconnecting the switch is smaller.

[0111] 8. At t = t7, the left switch S L The current path where it is located no longer carries current. At this time, the selected switch S1 no longer carries current and can be triggered to turn off. R The voltage across the two ends is controlled to be zero or close to zero.

[0112] 9. At t = t8, switch S R When the voltage across the two ends is zero or less than a certain threshold, the switch S R Trigger closing, during the closing process, dynamically control the controlled source to switch the switch S R The voltage across both ends is always zero, which allows it to close without an arc under zero voltage conditions.

[0113] 10. At t = t9, switch S R Fully closed, the right thyristor Stop conduction and disconnect the controlled source from the system. All load current is directed to the right switch S R In the branch where the on-load voltage regulator is located, it operates in a steady state at the voltage level where the transformer tap 2 is located, and the tap switching process is completed.

[0114] The above-mentioned tap switching method is also applicable to the load current transferring from right to left and the upward switching operation of the tap, ensuring that the voltage at both ends of the switch is zero or less than a certain threshold before and during closing, which can reduce the arc generated by contact breaking, reduce contact wear, and extend the service life of the switch.

[0115] The specific principle of the controlled source can be obtained by substituting the switching steps of the on-load tap changer and combining Figure 3 To understand:

[0116] 1. When the left switch S L Closed, right switch S R When it is turned on, the transformer operates stably at the voltage level where the odd-numbered tap is located, and the current I S1 =I AC , at this time the thyristor and controlled sources do not work.

[0117] 2. During the period from t2 to t5, the right thyristor In the on state, the controlled rectifier of the controlled source is controlled to make the right switch S R1 The voltage across the terminals V SR1 is zero, thus ensuring that the switch S R1No arc closure.

[0118] 3. At t=t6, trigger the left switch S L Disconnect, because at this time there is a switch in the closed state on both sides of the branch, switch S L The current carried is reduced, so the arc that opens the switch is smaller.

[0119] 4. After t7, the left switch S L The current path where it is located no longer carries current. At this time, the selected switch S1 no longer carries current and can be triggered to turn off. By controlling the controlled rectifier of the controlled source, the right switch S R The voltage across the terminals V SR is zero, thus ensuring that the switch S R No arc closure. All load current is directed to the right switch S R The branch where I S2 =I AC , the on-load voltage regulator operates in a steady state at the voltage level where the transformer tap 2 is located, and the tap switching process is completed.

[0120] The above describes the switching process of the transformer selection switch from top to bottom. The switching process from bottom to top is the same as the above process, but is performed in reverse.

[0121] In summary, the key technology of the present invention lies in the design of the controlled source with a flywheel motor, that is, the controlled source must be operated before the switching switch is closed to achieve a zero voltage condition at the switch break, so as to complete the arc-free closing of the switching switch of the on-load voltage regulator, reduce the loss of the switching switch contacts, and extend the service life of the equipment. It provides a way of thinking for the future optimization and improvement of the on-load voltage regulator, but further improvement is needed in the arc-free disconnection of the switching switch.

[0122] Example 3

[0123] This embodiment provides an electronic device, including: one or more processors and a memory, wherein the memory stores one or more programs, and the one or more programs include instructions for executing the flywheel energy storage arc-free switching contact adjustment method of the on-load tap-changing transformer as described in Example 2.

[0124] See also Fig.11 At the hardware level, the electronic device includes a processor, an internal bus, a network interface, a memory, and a non-volatile memory, and may also include other hardware required for the business. The processor reads the corresponding computer program from the non-volatile memory into the memory and then runs it to achieve the above Figure 1The flywheel energy storage arc-free switching contact adjustment method of the on-load voltage-changing transformer. Of course, in addition to the software implementation, the present invention does not exclude other implementations, such as logic devices or a combination of software and hardware, etc., that is, the execution subject of the following processing flow is not limited to each logic unit, but can also be hardware or logic devices.

[0125] The memory may include non-permanent storage in a computer-readable medium, random access memory (RAM) and / or non-volatile memory in the form of read-only memory (ROM) or flash RAM. The memory is an example of a computer-readable medium.

[0126] Computer readable media include permanent and non-permanent, removable and non-removable media that can be implemented by any method or technology to store information. Information can be computer readable instructions, data structures, program modules or other data. Examples of computer storage media include, but are not limited to, phase change memory (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other types of random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other memory technology, compact disk read-only memory (CD-ROM), digital versatile disk (DVD) or other optical storage, magnetic cassettes, magnetic disk storage or other magnetic storage devices or any other non-transmission media that can be used to store information that can be accessed by a computing device. As defined herein, computer readable media does not include temporary computer readable media (transitory media), such as modulated data signals and carrier waves.

[0127] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can easily think of various equivalent modifications or replacements within the technical scope disclosed by the present invention, and these modifications or replacements should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention shall be based on the protection scope of the claims.

Claims

1. A flywheel energy storage arc-free switching contact adjustment device for an on-load voltage-changing transformer, characterized in that: include: power supply; A transformer, comprising a primary side and a secondary side, wherein the power supply is connected to the primary side of the transformer; A transformer gating switch group connected to the primary side of the transformer; A switching switch connected to the transformer gating switch group, wherein the power supply, the transformer, the transformer gating switch group and the switching switch form a current path; A transition resistor and a transition branch switch are connected in parallel with the switching switch; A controlled source is connected to the switching switch, and the controlled source includes a flywheel motor. During the closing process of the switching switch, the flywheel motor provides a zero voltage condition for the switching switch to be closed, and reduces the current passing through when the closed switching switch is opened during the switching contact process, thereby weakening the arc generated by the switching of the switching switch.

2. The flywheel energy storage arc-free switching contact adjustment device of an on-load voltage-changing transformer according to claim 1 is characterized in that: The transformer gating switch group includes multiple gating switches, including two switching switches, namely a first switching switch and a second switching switch. The multiple gating switches are divided into a first gating switch set and a second gating switch set. One end of each gating switch in the first gating switch set is connected to the primary side of the transformer, and the other end is connected to the first switching switch. One end of each gating switch in the second gating switch set is connected to the primary side of the transformer, and the other end is connected to the second switching switch.

3. The flywheel energy storage arc-free switching contact adjustment device of the on-load voltage-changing transformer according to claim 2 is characterized in that: The controlled source also includes: An AC / DC converter connected to the flywheel motor; A DC / AC converter connected to the AC / DC converter; A first semiconductor unit, one end of which is connected to the DC / AC converter, and the other end of which is connected to the first switch; A second semiconductor unit has one end connected to the DC / AC converter and the other end connected to the second switch.

4. The flywheel energy storage arc-free switching contact adjustment device of an on-load voltage-changing transformer according to claim 3 is characterized in that: A mechanical switch is also connected in series with the branch where any one of the first semiconductor unit and the second semiconductor unit is located.

5. The flywheel energy storage arc-free switching contact adjustment device of an on-load voltage-changing transformer according to claim 3 is characterized in that: The semiconductor unit includes: The thyristor pairs arranged in anti-parallel are respectively connected to the corresponding switching switches and the DC / AC converter; A snubber is connected in parallel with the thyristor pair.

6. The flywheel energy storage arc-free switching contact adjustment device of an on-load voltage-changing transformer according to claim 1, characterized in that: Also includes: A load is connected to the secondary side of the transformer.

7. The flywheel energy storage arc-free switching contact adjustment device of an on-load voltage-changing transformer according to claim 1, characterized in that: The switching switch is a mechanical switching switch, and the selection switch in the transformer selection switch group is an on-load tap changer selector.

8. The flywheel energy storage arc-free switching contact adjustment device of an on-load voltage-changing transformer according to claim 1, characterized in that: The plurality of switching switches in the transformer switching switch group correspond to (1±2×2.5%) U N Voltage level, where U N is the rated voltage of the transformer.

9. The flywheel energy storage arc-free switching contact adjustment device of an on-load voltage-changing transformer according to claim 1, characterized in that: The flywheel rotor of the flywheel motor is connected to the motor rotor through a bearing, and the flywheel is driven to rotate through the motor rotor.

10. A method for adjusting flywheel energy storage arc-free switching contacts of an on-load voltage-changing transformer, applied to the flywheel energy storage arc-free switching contact adjusting device of an on-load voltage-changing transformer as claimed in any one of claims 1 to 9, the adjustment method comprising the following steps: Step S1, obtaining a load voltage value; Step S2, determining whether the load voltage fluctuation range exceeds a preset limit, if so, executing step S3, if not, executing step S1; Step S3, determining whether the load voltage value exceeds the voltage upper limit, if so, executing step S4, if not, executing step S7; Step S4, determine whether the tap is adjusted to the lower limit, if yes, execute step S1, if no, execute step S5; Step S5, determine whether the superior has taken action, if not, execute step S1, if yes, execute step S6; Step S6, the selector moves downward, triggering the thyristor corresponding to the switch on the side to be closed to turn on, realizing arc-free closing of the transition branch switch, adjusting the controlled source to achieve zero voltage during the closing of the transition branch switch, disconnecting the switch on the opposite side of the side to be closed, and then controlling the controlled source to achieve arc-free closing of the switch on the side to be closed, adjusting the controlled source to achieve zero voltage during the closing of the switch, turning off the thyristor, updating the load voltage value and judging whether the load voltage value exceeds the voltage upper limit, if yes, executing step S4, if not, executing step S1; Step S7, determine whether the tap is adjusted to the upper limit, if so, execute step S1, if not, execute step S8; Step S8, determine whether the superior has taken action, if not, execute step S1, if yes, execute step S9; Step S9, the selector moves upward, triggering the thyristor corresponding to the switching switch on the side to be closed to turn on, realizing arc-free closing of the transition branch switch, and during the closing period of the transition branch switch, the controlled source is adjusted to achieve zero voltage, and the switching switch on the opposite side to be closed is disconnected, and then the controlled source is controlled to achieve arc-free closing of the switching switch on the side to be closed. During the closing period of the switching switch, the controlled source is adjusted to achieve zero voltage, the thyristor is turned off, the load voltage value is updated and it is determined whether the load voltage value is lower than the lower limit of the voltage value. If so, execute step S7, if not, execute step S1.

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