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CN-122026276-A - Power plant transformer protection device and method

CN122026276ACN 122026276 ACN122026276 ACN 122026276ACN-122026276-A

Abstract

The invention relates to the technical field of transformers, in particular to a power plant transformer protection device and method, comprising an analog quantity acquisition module, a verification module, a switching quantity input and output module, an output relay and a protection DSP, wherein the analog quantity acquisition module is used for acquiring alternating current signals and alternating voltage signals at each side of a transformer, the verification module comprises a protection DSP and a starting DSP, the protection DSP and the starting DSP respectively and independently receive the same group of alternating current signals and alternating voltage signals output by the analog quantity acquisition module, the switching quantity input and output module comprises the output relay, the protection DSP and the starting DSP synchronously receive external switching signals of the switching quantity input and output module, the input end of the output relay is simultaneously connected with the output ends of the protection DSP and the starting DSP, and the protection DSP and the starting DSP adopt AND gate outlet logic, and the protection DSP is only used for switching on a positive power supply of the output relay and driving tripping when the protection DSP outputs the protection action signals and the starting DSP outputs the starting action signals. The reliability of the protection device is improved.

Inventors

  • LI HAIJUN
  • SUN LIGUO
  • CAI XI
  • YAO LIANG
  • QIANG LINLIN
  • MA ZHIZHONG
  • YUAN YE
  • MENG XIANYU
  • LIU WEN

Assignees

  • 中国三峡建工(集团)有限公司
  • 南京南瑞继保工程技术有限公司

Dates

Publication Date
20260512
Application Date
20260211

Claims (10)

  1. 1. A power plant transformer protection device is characterized by comprising, An analog quantity acquisition module (100) for acquiring alternating current signals and alternating voltage signals on each side of the transformer (101); the verification module (200) comprises a protection DSP (201) and a starting DSP (202), wherein the protection DSP (201) and the starting DSP (202) respectively and independently receive the same group of alternating current signals and alternating voltage signals output by the analog quantity acquisition module (100); The switching value input/output module (300) comprises an outlet relay (301), wherein the protection DSP (201) and the starting DSP (202) synchronously receive external switching signals of the switching value input/output module (300), the input end of the outlet relay (301) is simultaneously connected with the output ends of the protection DSP (201) and the starting DSP (202), the protection DSP (201) and the starting DSP (202) adopt AND gate outlet logic, and the protection DSP (201) only conducts a positive power supply of the outlet relay (301) and drives tripping when the protection DSP (201) outputs a protection action signal and the starting DSP (202) outputs a starting action signal.
  2. 2. The power plant transformer protection device according to claim 1, wherein the alternating current signal and the alternating voltage signal are input to the protection DSP (201) and the starting DSP (202) by the analog quantity acquisition module (100) after isolation, low-pass filtering and A/D conversion; and the protection DSP (201) and the starting DSP (202) are subjected to data interaction and mutual detection, and if the protection DSP (201) and/or the starting DSP (202) detect faults, the protection device locks all protection functions and sends out alarm signals.
  3. 3. The power plant transformer protection device according to claim 1 or 2, wherein the protection DSP (201) comprises a differential steady state ratio differential protection unit (201 a), and an equation of motion of the differential steady state ratio differential protection unit (201 a) satisfies: When (when) In the time-course of which the first and second contact surfaces, ; When (when) In the time-course of which the first and second contact surfaces, ; Wherein, the In order to brake the current flow, In order to fix the brake current multiple, Is used for rated current of the transformer (101), In the case of a differential current flow, For the initial ratio differential slope to be the same, The range of (2) is 0.05 to 0.15, For the differential current to start up to a fixed value, Is the maximum ratio differential slope that will be described in terms of, In the range of 0.50 to 0.80, Is a slope transition compensation value.
  4. 4. The power plant transformer protection device according to claim 3, wherein the longitudinal differential steady-state ratio differential protection unit (201 a) further comprises a magnetizing inrush current blocking element (201 a-1), the magnetizing inrush current blocking element (201 a-1) selecting a second harmonic braking discrimination logic or a waveform discrimination logic by a control word; if the second harmonic braking discrimination logic is selected, the action equation is: ; Wherein the method comprises the steps of For the second harmonic component of the difference stream, For the second harmonic braking coefficient, The range of (2) is 0.1 to 0.35, Is the fundamental component of the differential stream; if the waveform discrimination logic is selected, the following requirements are satisfied: And is also provided with ; Otherwise, judging the exciting current as the exciting current, wherein, As the differential current full-cycle integrated value, The differential current instantaneous value is added to the full cycle integral value of the differential current instantaneous value before half cycle, For a fixed constant, The threshold value is set; the expression of (2) is as follows: ; Wherein, the Is a first constant of the ratio, Is the full-cycle integral value of the difference current, The current is rated for the transformer (101).
  5. 5. The power plant transformer protection device according to claim 1 or 2, wherein the protection DSP (201) further comprises a zero sequence ratio differential protection unit (201 b), the zero sequence ratio differential protection unit (201 b) is used for high voltage side and branch ground fault protection, and the action equation thereof satisfies: ; ; Wherein, the Is a zero-sequence differential current, Is a zero sequence ratio differential start fixed value, Is in the range of 0.1 ~1.5 , Is the zero sequence differential ratio brake coefficient, Is in the range of 0.3 to 0.8, Taking the maximum value of each side zero sequence current for the zero sequence differential braking current, For the secondary rated current of the CT, The value is 1A or 5A.
  6. 6. The power plant transformer protection device according to claim 5, wherein the zero sequence ratio differential protection unit (201 b) further comprises a CT saturation blocking element (201 b-1), and the CT saturation blocking element (201 b-1) is blocked by a positive sequence current braking criterion and a comprehensive harmonic criterion; the positive sequence current braking criterion is Wherein For a certain side zero sequence current, For the corresponding side positive sequence current, Is a second proportionality constant; The comprehensive harmonic criterion is Wherein For the phase currents to be synthesized to be harmonic, For the fundamental wave of the phase current, Is a third proportionality constant.
  7. 7. The power plant transformer protection device according to claim 1 or 2, wherein the protection DSP (201) further comprises an over-excitation protection unit (201 c), the over-excitation protection unit (201 c) employs a timing protection logic and an inverse timing protection logic, wherein, Setting a jump lock chamber and an alarm section by timing protection logic, wherein the range of the U/F fixed value of the jump lock chamber is 1.0-2.0, the time delay is 0.1-3000 seconds, the range of the U/F fixed value of the alarm section is 1.0-2.0, and the time delay is 0.1-30 seconds; the equation of motion of the inverse time limit protection logic is expressed as: ; Wherein, the For an action delay of the inverse time-limited protection, As a function of the time coefficient, As a function of the time constant, Is the actual overexcitation current of the transformer (101), As a reference current, the reference current is set, Is an index.
  8. 8. The power plant transformer protection device according to claim 2, wherein the switching value input/output module (300) comprises a strong-weak current mixed switching plug-in unit (302), and the strong-weak current mixed switching plug-in unit (302) is configured with multiple strong-current switching and multiple weak-current switching; the switching value input/output module (300) is also provided with a plurality of signal plug-ins, an alarm signal output 3 instantaneous contacts, a tripping signal output 1 magnetic holding contact and 2 instantaneous contacts.
  9. 9. The power plant transformer protection device according to claim 1 or 2, wherein the protection DSP (201) further comprises, A CT disconnection warning unit (201 d), the action criterion of which is expressed as: ; Wherein, the In order to self-produce the zero-sequence current, For the secondary rated current of the CT, For the maximum phase current, a CT abnormal alarm signal is sent out after a delay of 10 seconds after the criterion is met; PT disconnection alarm unit (201 e) with positive sequence voltage <18V and any phase current >0.04 Or negative sequence voltage 3U2>8V, the PT disconnection of the high-voltage side and the PT disconnection of the branch meet any condition of the PT disconnection alarming unit (201 e), and corresponding PT disconnection alarming signals are sent out after time delay for 10 s.
  10. 10. The power plant-based transformer protection method is characterized by comprising the following steps of: The protection DSP (201) and the starting DSP (202) respectively perform hardware self-test, and enter an operation mode if the self-test passes; The analog quantity acquisition module (100) acquires current and voltage signals, the current and voltage signals are transmitted to the protection DSP (201) and the starting DSP (202) after tempering, the starting DSP (202) judges whether to start according to a longitudinal error protection starting element, an overcurrent protection starting element and a zero sequence protection starting element, and the positive power supply of the outlet relay (301) is opened by stretching 500ms after starting; After the starting DSP (202) starts the action, the protection DSP (201) executes protection algorithm calculation including differential protection, overcurrent protection and overexcitation protection, and performs data interaction with the starting DSP (202), and when the protection DSP (201) and the starting DSP (202) determine faults, the outlet relay (301) is triggered; In the fault processing process, if CT or PT disconnection is detected, an alarm signal is sent and locking is executed.

Description

Power plant transformer protection device and method Technical Field The invention relates to the technical field of transformers, in particular to a power plant transformer protection device and method. Background The transformer is used as core equipment in a power plant power system, and the stable operation of the transformer directly determines the continuity and safety of power transmission. With the continuous expansion of the capacity of a power plant unit, working conditions faced by a transformer are more complex, internal faults such as winding short circuit, iron core overheating, external faults such as line grounding, overload and abnormal working conditions such as excitation surge current and CT/PT disconnection can cause equipment damage, even large-area power failure accidents are caused, and huge economic losses are caused. In the prior art, a single DSP module is adopted to realize protection logic operation in the power plant transformer protection device, and obvious reliability defects exist, namely, if a hardware fault or abnormal sampling occurs in the single DSP module, the single DSP module is easy to cause protection misoperation or refusal operation, and the severe requirements of the power plant on zero misoperation or zero refusal operation of the protection device cannot be met. In addition, the switching value input/output module of the existing protection device is designed to be opened in a single type, cannot be compatible with external state signals with different voltage levels, is poor in universality, is insufficient in contact point configuration of fault alarm and tripping signals, and cannot meet the requirement of a power plant on redundant signal transmission. Disclosure of Invention Some simplifications or omissions may be made in this section as well as in the description of the application and in the title of the application, which may not be used to limit the scope of the application. In order to solve the defects of the prior art, the invention provides a power plant transformer protection device which comprises an analog quantity acquisition module, a verification module and a switching quantity input/output module, wherein the analog quantity acquisition module is used for acquiring alternating current signals and alternating voltage signals at each side of a transformer, the verification module comprises a protection DSP and a starting DSP, the protection DSP and the starting DSP respectively and independently receive the same group of alternating current signals and alternating voltage signals output by the analog quantity acquisition module, the switching quantity input/output module comprises an outlet relay, the protection DSP and the starting DSP synchronously receive external switching signals of the switching quantity input/output module, the input end of the outlet relay is simultaneously connected with the protection DSP and the output end of the starting DSP, the protection DSP and the starting DSP adopt AND gate outlet logic, and the positive power supply of the outlet relay is conducted and tripped only when the protection DSP outputs the protection action signals and the starting DSP outputs the starting action signals. The power plant transformer protection device is characterized in that an alternating current signal and an alternating voltage signal are input into the protection DSP and the starting DSP through the analog quantity acquisition module after being isolated, low-pass filtered and A/D converted, the protection DSP and the starting DSP are subjected to data interaction and mutual detection, and if the protection DSP and/or the starting DSP detect faults, the protection device locks all protection functions and sends out alarm signals. As a preferable scheme of the power plant transformer protection device, the protection DSP comprises a longitudinal differential steady-state ratio differential protection unit, and an action equation of the longitudinal differential steady-state ratio differential protection unit meets the following conditions: When (when) In the time-course of which the first and second contact surfaces,; When (when)In the time-course of which the first and second contact surfaces,; Wherein, the In order to brake the current flow,In order to fix the brake current multiple,For the rated current of the transformer,In the case of a differential current flow,For the initial ratio differential slope to be the same,The range of (2) is 0.05 to 0.15,For the differential current to start up to a fixed value,Is the maximum ratio differential slope that will be described in terms of,In the range of 0.50 to 0.80,Is a slope transition compensation value. The power plant transformer protection device is characterized in that the longitudinal differential steady-state ratio differential protection unit further comprises a magnetizing inrush current blocking part, wherein the magnetizing inrush current blocking part selects sec