CN111478299A - Impulse current limiting circuit for sudden short circuit of transformer - Google Patents

Impulse current limiting circuit for sudden short circuit of transformer Download PDF

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Publication number
CN111478299A
CN111478299A CN202010288830.4A CN202010288830A CN111478299A CN 111478299 A CN111478299 A CN 111478299A CN 202010288830 A CN202010288830 A CN 202010288830A CN 111478299 A CN111478299 A CN 111478299A
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China
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frequency
bridge module
low
bridge
pwm
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Pending
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CN202010288830.4A
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Chinese (zh)
Inventor
郑志曜
李志�
高一波
杨瀚鹏
余绍峰
吴钢
蔡新华
袁衢龙
盛况
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Beijing Keliyuan Energy Technology Co ltd
State Grid Corp of China SGCC
Zhejiang Huadian Equipment Inspection Institute
State Grid Zhejiang Electric Power Co Ltd
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Beijing Keliyuan Energy Technology Co ltd
State Grid Corp of China SGCC
Zhejiang Huadian Equipment Inspection Institute
State Grid Zhejiang Electric Power Co Ltd
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Application filed by Beijing Keliyuan Energy Technology Co ltd, State Grid Corp of China SGCC, Zhejiang Huadian Equipment Inspection Institute, State Grid Zhejiang Electric Power Co Ltd filed Critical Beijing Keliyuan Energy Technology Co ltd
Priority to CN202010288830.4A priority Critical patent/CN111478299A/en
Publication of CN111478299A publication Critical patent/CN111478299A/en
Pending legal-status Critical Current

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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
    • H02H9/00—Emergency protective circuit arrangements for limiting excess current or voltage without disconnection
    • H02H9/02—Emergency protective circuit arrangements for limiting excess current or voltage without disconnection responsive to excess current
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
    • H02H9/00—Emergency protective circuit arrangements for limiting excess current or voltage without disconnection
    • H02H9/04—Emergency protective circuit arrangements for limiting excess current or voltage without disconnection responsive to excess voltage
    • H02H9/045—Emergency protective circuit arrangements for limiting excess current or voltage without disconnection responsive to excess voltage adapted to a particular application and not provided for elsewhere
    • H02H9/047—Free-wheeling circuits

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Rectifiers (AREA)

Abstract

The invention belongs to the technical field of short-circuit resistance tests of transformers, and particularly provides an impulse current limiting circuit for sudden short circuits of a transformer. The high-frequency power supply system is composed of a single-phase rectifier transformer (1), a PWM (pulse-width modulation) rectification H-bridge module (2), a discharge branch circuit (3), a low-frequency cascade H-bridge module (4), a high-frequency H-bridge module (5), a high-frequency connecting reactor (6), a low-frequency connecting reactor (7) and a system access point (8). The high-frequency H-bridge module (5) generates 11-31 times of harmonic current, the low-frequency cascade H-bridge module (4) generates 2-10 times of harmonic voltage, and harmonic current superposition output is formed at a system access point (8) through the high-frequency connecting reactor (6) and the low-frequency connecting reactor (7) respectively. The invention has the advantages that: the device obviously expands the generation range of harmonic current, reduces the total switching loss of the device, realizes decoupling control among different frequency modules, improves the working condition of power electronic devices and improves the reliability.

Description

Impulse current limiting circuit for sudden short circuit of transformer
Technical Field
The invention belongs to the technical field of short-circuit resistance tests of transformers, and particularly provides an impulse current limiting circuit for sudden short circuits of a transformer.
Background
The transformer winding faults are mostly the similar faults caused by insufficient short-circuit resistance of the winding, distortion and deformation of the winding, falling off and displacement of a cushion block and the accumulation effect of long-term operation when the short-circuit fault occurs suddenly. And after the transient component of the short-circuit current in the short-circuit fault is superposed with the direct-current component, the amplitude value is far higher than that of the steady-state short-circuit current, so that the transformer winding bears huge voltage and current stress and electrodynamic force generated by the voltage and current stress, and the fault damage risk is increased.
To limit the transformer short circuit current, a series element is typically used to increase the system impedance. Although the fault current level can be limited in the fault period in this way, under the normal operation state of the system, the voltage drop is obvious due to the introduction of the system impedance, and the safe and stable operation and the efficiency improvement of the system are not facilitated. If a certain device can limit short-circuit current under the fault condition, and can not increase system impedance under the normal condition, the system running efficiency is fully exerted, and the cost is not high, and the requirement for improving the short-circuit resistance of a large number of transformers in the current system can be met.
In general, a series device is connected to a system through a series transformer, and when a transformer in the system is suddenly short-circuited, the device injects compensation voltage to reduce the level of short-circuit current caused by short circuit of the transformer. However, series transformers also face a large impact of short circuit currents, and face both cost and technical challenges in designing capacity and control protection strategies. If the steady-state level of the short-circuit current is limited without considering the injection of the reverse compensation voltage and only the transient component of the short-circuit of the transformer is limited, the impact current level borne by the protected transformer can be obviously reduced without obviously increasing the cost of the compensation equipment. For the compensation equipment, not only the injected voltage can cause the self-large excitation surge current to threaten the safe operation of the injection transformer and the inverter, but also the possibility of the relay protection misoperation is greatly increased, and the power supply reliability is reduced. Therefore, the problem of suppression of transient current caused by transformer short circuit is studied by control, and the method has obvious practical significance. At present, no relevant research report is found in domestic and foreign publications.
Disclosure of Invention
The invention provides an impulse current limiting circuit for sudden short circuit of a transformer, which is used for inhibiting impulse short circuit current generated by a short circuit resistance test of the transformer supplied by a power distribution network.
The high-frequency high-voltage power supply comprises a single-phase rectifier transformer 1, a PWM (pulse-width modulation) rectifier H-bridge module 2, a discharge branch 3, a low-frequency cascade H-bridge module 4, a high-frequency H-bridge module 5, a high-frequency connecting reactor 6, a low-frequency connecting reactor 7 and a system access point 8.
After the single-phase rectifier transformer 1 reduces the voltage of the alternating current power supply, the N PWM rectifier H-bridge modules 2 are charged through N (the value range of N is 3-15) low-voltage windings respectively, and the direct current bus voltage is established. And a discharging branch circuit 3 is connected in parallel to a direct current bus of each PWM rectification H-bridge module. The N PWM rectification H-bridge modules are divided into two groups, one group is composed of one PWM rectification H-bridge module, a direct current bus of the PWM rectification H-bridge module is connected with the input end of the high-frequency H-bridge module 5, the other group is composed of N-1 PWM rectification H-bridge modules, and direct current buses of the PWM rectification H-bridge modules are respectively connected with the input ends of the N-1 low-frequency cascade H-bridge modules 4. One output end a of the high-frequency H-bridge module 5 is connected to a point B of the low-frequency connecting reactor 7 through the high-frequency connecting reactor 6, and then connected to the system access point 8, and the other end of the high-frequency H-bridge module 5 is connected to a point C of the low-frequency connecting reactor 7. The low-frequency cascade H-bridge module 4 is formed by connecting N-1 single-phase H-bridge modules in series, one end of series output is connected to a point C of the low-frequency connecting reactor 7, and the other end of the series output is connected to a neutral point D.
The high-frequency H-bridge module 5 generates 11-31 times of harmonic current, the low-frequency cascade H-bridge module 4 generates 2-10 times of harmonic voltage, and harmonic current superposition output is formed at a system access point 8 through the high-frequency connecting reactor 6 and the low-frequency connecting reactor 7 respectively.
After the single-phase rectifier transformer 1 reduces the voltage of the alternating current power supply, N (the value range of N is 3-15) PWM rectification H-bridge modules 2 are charged through N low-voltage windings respectively, and the direct current bus voltage is established. The discharging branch circuit 3 is connected in parallel to the direct current bus of each PWM rectification H-bridge module, when overvoltage occurs to the direct current bus, the discharging branch circuit 3 discharges rapidly, the voltage of the direct current bus is controlled not to be over-limited, and the safety of power electronic devices is protected. The N PWM rectification H-bridge modules are divided into two groups, one group is composed of one PWM rectification H-bridge module, a direct current bus of the PWM rectification H-bridge module is connected with the input end of the high-frequency H-bridge module 5, the other group is composed of N-1 PWM rectification H-bridge modules, and direct current buses of the PWM rectification H-bridge modules are respectively connected with the input ends of the N-1 low-frequency cascade H-bridge modules 4. One output end a of the high-frequency H-bridge module 5 is connected to a point B of the low-frequency connecting reactor 7 through the high-frequency connecting reactor 6, and then connected to the system access point 8, and the other end of the high-frequency H-bridge module 5 is connected to a point C of the low-frequency connecting reactor 7. The low-frequency cascade H-bridge module 4 is formed by connecting N-1 single-phase H-bridge modules in series, one end of series output is connected to a point C of the low-frequency connecting reactor 7, and the other end of the series output is connected to a neutral point D.
The working principle of the impulse current limiting circuit for the sudden short circuit of the transformer is that after an alternating current power supply is subjected to voltage reduction and isolation through a single-phase rectifier transformer, N PWM rectification H-bridge modules are charged through N low-voltage windings respectively, and a direct current bus voltage is established. The direct current bus of each PWM rectification H-bridge module is connected with a discharge branch in parallel, when overvoltage occurs to the direct current bus, the discharge branch discharges rapidly, and the voltage of the direct current bus is controlled not to be over-limited, so that the safety of power electronic devices is protected. The N PWM rectification H-bridge modules are divided into two groups, one group is composed of one PWM rectification H-bridge module, a direct current bus of the PWM rectification H-bridge module is connected with the input end of the high-frequency H-bridge module, the other group is composed of N-1 PWM rectification H-bridge modules, and direct current buses of the PWM rectification H-bridge modules are respectively connected with the input ends of the N-1 low-frequency cascade H-bridge modules. The high-frequency H-bridge module 5 is used as a constant current source to generate 11-31 times of higher harmonic current according to a control instruction based on a hysteresis current control algorithm and is connected to a system access point 8 through a high-frequency connecting reactor 6; the low-frequency cascade H-bridge module 4 is used as a constant voltage source to generate 2-10 times lower harmonic voltage according to a control instruction based on a carrier phase shift control algorithm, the harmonic voltage is connected to a system access point 8 through a low-frequency connecting reactance 7 to generate corresponding 2-10 times harmonic current, and the harmonic current generated by the high-frequency H-bridge module and 11-31 times harmonic current generated by the high-frequency H-bridge module are overlapped at the system access point 8 to form finally generated total harmonic current.
The invention has the advantages that: the device obviously expands the range of transient component harmonic current generation during the short-circuit resistance test of the offset transformer, reduces the total switching loss of the device, realizes decoupling control among different frequency modules, improves the working conditions of power electronic devices and improves the reliability.
Drawings
Fig. 1 is a main circuit topology diagram of a hybrid frequency control harmonic current generation device according to the present invention. The system comprises a single-phase rectifier transformer 1, a PWM (pulse-width modulation) rectification H-bridge module 2, a discharge branch 3, a low-frequency cascade H-bridge module 4, a high-frequency H-bridge module 5, a high-frequency connecting reactor 6, a low-frequency connecting reactor 7 and a system access point 8.
Detailed Description
The main circuit structure diagram of the mixed frequency control harmonic current generating device is shown in figure 1 and comprises a single-phase rectifier transformer 1, a PWM (pulse-width modulation) rectifier H-bridge module 2, a discharge branch 3, a low-frequency cascade H-bridge module 4, a high-frequency H-bridge module 5, a high-frequency connecting reactor 6, a low-frequency connecting reactor 7 and a system access point 8.
After the single-phase rectifier transformer 1 reduces the voltage of the alternating current power supply, the N PWM rectifier H-bridge modules 2 are charged through the N low-voltage windings respectively, and the direct current bus voltage is established. And a discharging branch circuit 3 is connected in parallel to a direct current bus of each PWM rectification H-bridge module.
The N PWM rectification H-bridge modules are divided into two groups, one group is composed of one PWM rectification H-bridge module, a direct current bus of the PWM rectification H-bridge module is connected with the input end of the high-frequency H-bridge module 5, the other group is composed of N-1 PWM rectification H-bridge modules, and direct current buses of the PWM rectification H-bridge modules are respectively connected with the input ends of the N-1 low-frequency cascade H-bridge modules 4. One output end a of the high-frequency H-bridge module 5 is connected to a point B of the low-frequency connecting reactor 7 through the high-frequency connecting reactor 6, and then connected to the system access point 8, and the other end of the high-frequency H-bridge module 5 is connected to a point C of the low-frequency connecting reactor 7. The low-frequency cascade H-bridge module 4 is formed by connecting N-1 single-phase H-bridge modules in series, one end of series output is connected to a point C of the low-frequency connecting reactor 7, and the other end of the series output is connected to a neutral point D.

Claims (2)

1. The inrush current limiting circuit for the sudden short circuit of the transformer is characterized by comprising a single-phase rectifier transformer (1), a PWM (pulse-width modulation) rectification H-bridge module (2), a discharge branch (3), a low-frequency cascade H-bridge module (4), a high-frequency H-bridge module (5), a high-frequency connecting reactance (6), a low-frequency connecting reactance (7) and a system access point (8); after the single-phase rectifier transformer (1) reduces the voltage of the alternating current power supply, the N PWM rectifier H-bridge modules (2) are charged through N low-voltage windings (the value range of N is 3-15) respectively, and the direct current bus voltage is established. And a discharging branch circuit (3) is connected in parallel to a direct current bus of each PWM rectification H-bridge module. The N PWM rectification H-bridge modules are divided into two groups, one group is composed of one PWM rectification H-bridge module, a direct current bus of the PWM rectification H-bridge module is connected with the input end of the high-frequency H-bridge module (5), the other group is composed of N-1 PWM rectification H-bridge modules, and direct current buses of the PWM rectification H-bridge modules are respectively connected with the input ends of the N-1 low-frequency cascade H-bridge modules (4). One output end A of the high-frequency H-bridge module (5) is connected with a point B of the low-frequency connecting reactor (7) after passing through the high-frequency connecting reactor (6), and then is connected to a system access point (8) together, and the other end of the high-frequency H-bridge module (5) is connected with a point C of the low-frequency connecting reactor (7). The low-frequency cascade H-bridge module (4) is formed by connecting N-1 single-phase H-bridge modules in series, one end of series output is connected to a point C of the low-frequency connection reactor (7), and the other end of the series output is connected to a neutral point D; the high-frequency H-bridge module (5) generates 11-31 times of harmonic current, the low-frequency cascade H-bridge module (4) generates 2-10 times of harmonic voltage, and harmonic current superposition output is formed at a system access point (8) through the high-frequency connecting reactor (6) and the low-frequency connecting reactor (7) respectively.
2. The circuit according to claim 1, characterized in that the N (N ranges from 3 to 15) PWM rectifying H-bridge modules (2) are divided into two groups, one of which consists of one PWM rectifying H-bridge module with its dc bus connected to the input of the high frequency H-bridge module (5), and the other of which consists of N-1 PWM rectifying H-bridge modules with their dc buses connected to the inputs of the N-1 low frequency cascaded H-bridge modules (4), respectively. The high-frequency H-bridge module (5) is used as a constant current source to generate 11-31 times of higher harmonic current according to a control instruction based on a hysteresis current control algorithm and is connected to a system access point 8 through a high-frequency connecting reactor (6); the low-frequency cascade H-bridge module (4) is used as a constant voltage source to generate 2-10 times lower harmonic voltage according to a control instruction based on a carrier phase shift control algorithm, the harmonic voltage is connected to a system access point (8) through a low-frequency connecting reactance (7) to generate corresponding 2-10 times harmonic current, and the harmonic current and 11-31 times harmonic current generated by the high-frequency H-bridge module are superposed at the system access point (8) to form finally generated total harmonic current.
CN202010288830.4A 2020-04-13 2020-04-13 Impulse current limiting circuit for sudden short circuit of transformer Pending CN111478299A (en)

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Application Number Priority Date Filing Date Title
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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN112710879A (en) * 2021-03-26 2021-04-27 中国电力科学研究院有限公司 Multiple harmonic wave superposition current generation device and method for temperature rise test

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN112710879A (en) * 2021-03-26 2021-04-27 中国电力科学研究院有限公司 Multiple harmonic wave superposition current generation device and method for temperature rise test

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