CN109672145B - Method for establishing inverse time-limit model for processing time-varying load and overload protection method - Google Patents

Method for establishing inverse time-limit model for processing time-varying load and overload protection method Download PDF

Info

Publication number
CN109672145B
CN109672145B CN201811562231.6A CN201811562231A CN109672145B CN 109672145 B CN109672145 B CN 109672145B CN 201811562231 A CN201811562231 A CN 201811562231A CN 109672145 B CN109672145 B CN 109672145B
Authority
CN
China
Prior art keywords
time
model
per unit
unit value
overload
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Active
Application number
CN201811562231.6A
Other languages
Chinese (zh)
Other versions
CN109672145A (en
Inventor
田凯
张策
杨淦
赵金鹏
魏维
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Electric Power Research Institute of State Grid Tianjin Electric Power Co Ltd
Original Assignee
Electric Power Research Institute of State Grid Tianjin Electric Power Co Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Electric Power Research Institute of State Grid Tianjin Electric Power Co Ltd filed Critical Electric Power Research Institute of State Grid Tianjin Electric Power Co Ltd
Priority to CN201811562231.6A priority Critical patent/CN109672145B/en
Publication of CN109672145A publication Critical patent/CN109672145A/en
Application granted granted Critical
Publication of CN109672145B publication Critical patent/CN109672145B/en
Active legal-status Critical Current
Anticipated expiration legal-status Critical

Links

Images

Classifications

    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
    • H02H7/00—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions
    • H02H7/08—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for dynamo-electric motors
    • H02H7/085—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for dynamo-electric motors against excessive load

Landscapes

  • Protection Of Generators And Motors (AREA)
  • Control Of Electric Motors In General (AREA)

Abstract

The invention relates to a method for processing time-varying loadThe method for establishing the inverse time limit model of the load and protecting the overload comprises the following steps: establishing an inverse time-limited model for processing time-varying load as follows:
Figure DDA0001913564740000011
calculating heat dissipation coefficient K, integral constant C and equivalent thermal time constant T according to the overload protection characteristic valuenLoad current I and load equivalent resistance r at the moment t; k, C, T will be mixednAnd carrying out inverse time limit protection on the motor by utilizing the model. The invention has reasonable design, the established inverse time limit model has definite physical significance, can be realized without table lookup, and has the heat dissipation coefficient K and the equivalent thermal time constant TnOnly 1 time is calculated, so that the real-time model has small calculated amount and high speed, is convenient for DSP programming realization, and avoids the problems that the heat overload capacity of the motor cannot be fully utilized or the heat damage of the motor is caused by the time delay of the overload protection action caused by the advance overload protection action.

Description

Method for establishing inverse time-limit model for processing time-varying load and overload protection method
Technical Field
The invention belongs to the technical field of electrical control, and particularly relates to a method for establishing an inverse time-lag model for processing time-varying load and protecting overload.
Background
Overload can lead to the inside heat of motor to accumulate gradually during motor operation, and long-time overload operation can make the motor temperature rise gradually, and insulating material can accelerate ageing, burns out the motor when serious, consequently must take overload protection measure to the motor. Since the time allowed to heat up varies with the motor overload factor, the motor overload protection must comply with an inverse time limit characteristic, i.e. the time of the protection action is shorter as the overload factor increases.
The inverse time limit overload protection needs to act in real time according to the overload condition of the motor. If the overload protection action is advanced, the heat overload capacity of the motor cannot be fully utilized, so that the continuity of industrial production is influenced; if the overload protection operation time is delayed, the heat damage of the motor is easily caused.
Disclosure of Invention
The invention aims to overcome the defects of the prior art and provides a method for establishing an inverse time-lag model for processing time-varying load and protecting overload, which is reasonable in design, strong in real-time performance, accurate and reliable.
The technical problem to be solved by the invention is realized by adopting the following technical scheme:
an inverse time-lag model establishing and overload protecting method for processing time-varying load comprises the following steps:
step 1, establishing an inverse time-limit model for processing time-varying load as follows;
Figure BDA0001913564720000011
step 2, calculating a heat dissipation coefficient K, an integral constant C and an equivalent thermal time constant T according to the overload protection characteristic valuen；
Step 3, K, C, TnBringing the motor into an inverse time limit model and performing inverse time limit protection on the motor by using the model;
wherein, theta is temperature rise, P is heating power, r is equivalent resistance of the conductive load, and I is input current.
The heat dissipation coefficient K, the integral constant C and the equivalent thermal time constant TnThe calculation method comprises the following steps:
Figure BDA0001913564720000012
Figure BDA0001913564720000013
Figure BDA0001913564720000014
in the above formula, θ0For the initial temperature rise of the system, I0For the current at the initial time of the system (t ═ 0), IpFor an overcurrent, tpFor overload protectionAs time, θthIs the maximum temperature rise threshold of the motor, INThe starting current is protected for an inverse time-limited action.
When the current input is per unit value, the temperature rise calculation formula is
Figure BDA0001913564720000021
Wherein, theta is the temperature rise per unit value, I is the current per unit value, K is the heat dissipation coefficient after the per unit value is adopted, and T is the heat dissipation coefficientn *To adopt the thermal time constant after unit value, K ═ K/r, Tn *＝Tn/r；
Figure BDA0001913564720000022
Figure BDA0001913564720000023
Wherein, I0 *Is the current per unit value at the initial time (t ═ 0) of the system, Ip *Is the per unit value of the overload current, IN *Protecting the starting current per unit value, theta, for inverse time-limited actionth *Is the per unit value of the maximum temperature rise threshold.
The invention has the advantages and positive effects that:
1. the inverse time limit model established by the invention has definite physical significance, can be realized without table lookup, and has the heat dissipation coefficient K and the equivalent thermal time constant TnOnly 1 time is calculated, so that the real-time model has small calculated amount and high speed, is convenient for DSP programming realization, and avoids the problems that the heat overload capacity of the motor cannot be fully utilized or the heat damage of the motor is caused by the time delay of the overload protection action caused by the advance overload protection action.
2. The invention fully considers the initial state of the system, calculates the heating curve closer to the actual load, and effectively prevents the damage of the motor overload to the equipment.
3. The invention provides an inverse time-lag protection model when the input current is a per unit value, which has strong universality and can better adapt to various time-varying loads.
Drawings
FIG. 1 is a block diagram of inverse time-lag protection;
FIG. 2 is a block diagram of inverse time-lag protection when the input current is per unit;
FIG. 3 is an inverse time limit graph of I2T;
FIG. 4 is steady state I0 *The simulation graph of inverse time limit protection when the simulation graph is 100 percent;
FIG. 5 is steady state I0 *An inverse time limit protection simulation graph when the percentage is 110 percent;
FIG. 6 is steady state I0 *The inverse time-lag protection simulation graph at 90 percent.
Detailed Description
The embodiments of the present invention will be described in detail with reference to the accompanying drawings.
An inverse time-lag model establishing and overload protecting method for processing time-varying load comprises the following steps:
step 1, establishing an inverse time limit model for processing time-varying load.
In this step, the inverse time-lag protection model is shown in FIG. 1, where K is the heat dissipation coefficient and T isnIs an equivalent thermal time constant, TsIs a calculation period, and the calculation formula of the temperature rise theta is as follows:
Figure BDA0001913564720000024
wherein P is heating power, and P is I2r, r are load equivalent resistances, and the above equation can be equivalently processed as:
Figure BDA0001913564720000031
for both sides of the above equation
Figure BDA0001913564720000032
Is finished to obtain
Figure BDA0001913564720000033
Namely, it is
Figure BDA0001913564720000034
Figure BDA0001913564720000035
Figure BDA0001913564720000036
Figure BDA0001913564720000037
The following inverse time-limited model is finally obtained:
Figure BDA0001913564720000038
where θ is the temperature rise. From the above formula, when the current is constant, it is IxT → ∞ time θx＝Ix 2r/K
When theta is>θthAnd when the current time is longer than the preset time, the inverse time limit protection action is carried out.
And 2, calculating parameters in an inverse time-limit model for processing the time-varying load.
Parameters K, C, T in inverse time-lag modelnOverload protection characteristic value (overload current I) capable of being input by userpTime of overload protection action tpIn which IPAnd tpIs a point in the inverse time-limited characteristic curve) is calculated as follows:
when t is equal to 0, the initial temperature rise of the system is already theta0Then calculate out
Figure BDA0001913564720000039
Is substituted to obtain
Figure BDA00019135647200000310
The maximum temperature rise threshold of the motor is set to be thetathCorresponding to an allowable current of INAnd satisfy
Figure BDA00019135647200000311
Then define INTo protect the starting current for inverse time-limited action
Figure BDA00019135647200000312
When inputting current IPTime, protective action time tPSubstituting into formula (8) to obtain
Figure BDA00019135647200000313
Assuming that the system is in a stable state before overload sudden change, namely t is 0 moment, the temperature rise of the system is theta0Current is I0And satisfies K θ0＝I0 2r
Figure BDA0001913564720000041
Figure BDA0001913564720000042
Finally obtaining the equivalent thermal time constant TnComprises the following steps:
Figure BDA0001913564720000043
wherein, IpAnd tpIs a point in the inverse time-limited curve, according to IN，IpAnd tpDifferent inverse time characteristic curves can be determined which are adapted to different motor characteristics.
Step 3, obtaining parameters K, C and T in the step 2nAnd carrying out inverse time limit protection on the motor by utilizing the model.
In order to make the patent more versatile, the inverse time-limit protection method for the input current per unit is as follows:
when the current input is per unit value, the temperature rise calculation formula can be equivalent to
Figure BDA0001913564720000044
Wherein, theta is the temperature rise per unit value, I is the current per unit value, K is the heat dissipation coefficient after the per unit value is adopted, and T is the heat dissipation coefficientn *To adopt the thermal time constant after unit value, K ═ K/r, Tn *＝Tn/r
From the foregoing description, it can be seen that:
Figure BDA0001913564720000045
wherein, I0 *Is the current per unit value at the initial time (t ═ 0) of the system, Ip *Is the per unit value of the overload current, IN *Protecting the starting current per unit value, theta, for inverse time-limited actionth *Is the per unit value of the maximum temperature rise threshold.
A control block diagram for inverse time-limit protection by per unit value is shown in fig. 2.
For example, when calculated in per unit:
Figure BDA0001913564720000046
input device
Figure BDA0001913564720000047
tP＝60s，
Figure BDA0001913564720000048
Calculate out
Figure BDA0001913564720000049
FIG. 3 is the I2T inverse used in the present inventionTime-limited characteristic curve. In order to verify the correctness of the algorithm, MATLAB is adopted to perform simulation verification on the algorithm. Fig. 4-6 are graphs of simulation results, which can be obtained by comparison: the simulation result is consistent with the calculation result of the model of the invention, and the correctness of the inverse time limit model and the parameter calculation method provided by the invention are verified. FIG. 4 is a drawing showing
Figure BDA0001913564720000051
tP＝60s，
Figure BDA0001913564720000059
When the load is larger than the set load, the protection action time of adding 150% of load suddenly is 10 s; FIG. 5 is a schematic view of a process for producing a semiconductor device
Figure BDA0001913564720000053
tP＝60s，
Figure BDA00019135647200000510
When the load is larger than the set load, the protection action time of adding 150% of load suddenly is 8.3 s; FIG. 6 is a schematic view of
Figure BDA0001913564720000056
tP＝60s，
Figure BDA00019135647200000511
The protection operation time for the sudden load of 150% is 11.34 s.
It should be emphasized that the embodiments described herein are illustrative rather than restrictive, and thus the present invention is not limited to the embodiments described in the detailed description, but also includes other embodiments that can be derived from the technical solutions of the present invention by those skilled in the art.

Claims (2)

1. An inverse time-limit model establishing and overload protection method for processing time-varying load is characterized by comprising the following steps:
step 1, establishing an inverse time-limit model for processing time-varying load as follows;
Figure FDA0002393845610000011
step 2, calculating a heat dissipation coefficient K, an integral constant C and an equivalent thermal time constant T according to the overload protection characteristic valuenLoad current I and load equivalent resistance r at the moment t;
the heat dissipation coefficient K, the integral constant C and the equivalent thermal time constant TnThe calculation method comprises the following steps:
Figure FDA0002393845610000012
Figure FDA0002393845610000013
Figure FDA0002393845610000014
in the above formula, θ0For the initial temperature rise of the system, I0Is the initial current of the system, IpFor an overcurrent, tpFor overload protection action time, thetathIs the maximum temperature rise threshold of the motor, INProtecting the starting current for inverse time-limited action;
step 3, K, C, TnBringing the motor into an inverse time limit model and performing inverse time limit protection on the motor by using the model;
where θ is the temperature rise and P is the heating power.
2. The method for establishing an inverse time-lag model for processing time-varying load and protecting against overload as claimed in claim 1, wherein: when the current input is per unit value, the temperature rise calculation formula is as follows:
Figure FDA0002393845610000015
wherein, theta is the temperature rise per unit value, I is the current per unit value, and K is the heat dissipation coefficient after the per unit value is adopted，Tn *To adopt the thermal time constant after unit value, K ═ K/r, Tn *＝Tn/r；
Figure FDA0002393845610000016
Figure FDA0002393845610000017
Wherein, I0 *Current per unit value at time t ═ 0, Ip *Is the per unit value of the overload current, IN *Protecting the starting current per unit value, theta, for inverse time-limited actionth *Is the per unit value of the maximum temperature rise threshold.
CN201811562231.6A 2018-12-20 2018-12-20 Method for establishing inverse time-limit model for processing time-varying load and overload protection method Active CN109672145B (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN201811562231.6A CN109672145B (en) 2018-12-20 2018-12-20 Method for establishing inverse time-limit model for processing time-varying load and overload protection method

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN201811562231.6A CN109672145B (en) 2018-12-20 2018-12-20 Method for establishing inverse time-limit model for processing time-varying load and overload protection method

Publications (2)

Publication Number Publication Date
CN109672145A CN109672145A (en) 2019-04-23
CN109672145B true CN109672145B (en) 2020-05-29

Family

ID=66143998

Family Applications (1)

Application Number Title Priority Date Filing Date
CN201811562231.6A Active CN109672145B (en) 2018-12-20 2018-12-20 Method for establishing inverse time-limit model for processing time-varying load and overload protection method

Country Status (1)

Country Link
CN (1) CN109672145B (en)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN116526425A (en) * 2023-04-11 2023-08-01 上海华建电力设备股份有限公司 Digital implementation method for thermal overload protection of alternating current motor

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN104124666A (en) * 2014-07-25 2014-10-29 苏州汇川技术有限公司 Permanent magnet synchronous motor temperature rise protection method and system
JP2015050840A (en) * 2013-09-02 2015-03-16 パナソニック株式会社 Overload protection method and servo motor drive method in servo system
CN106849011A (en) * 2016-12-30 2017-06-13 南京埃斯顿自动控制技术有限公司 A kind of servomotor method for excessive heating protection

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2015050840A (en) * 2013-09-02 2015-03-16 パナソニック株式会社 Overload protection method and servo motor drive method in servo system
CN104124666A (en) * 2014-07-25 2014-10-29 苏州汇川技术有限公司 Permanent magnet synchronous motor temperature rise protection method and system
CN106849011A (en) * 2016-12-30 2017-06-13 南京埃斯顿自动控制技术有限公司 A kind of servomotor method for excessive heating protection

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
过载保护数学模型及其算法的研究;迟长春;《中国优秀博士学位论文全文数据库工程科技Ⅱ辑》;20090815;第13-16页 *

Also Published As

Publication number Publication date
CN109672145A (en) 2019-04-23

Similar Documents

Publication Publication Date Title
US7508642B2 (en) Method and apparatus applying virtual Δt trip criterion in power distribution
CN103094875B (en) A kind of solid-state power controller based on microcontroller implementation
CN101132129A (en) AC motor over-load inverse time-lag protection method based on heat accumulation
CN105443424B (en) Control device and method for inverter cooling fan
KR101694688B1 (en) Method for controlling the temperature of a glow plug
CN109672145B (en) Method for establishing inverse time-limit model for processing time-varying load and overload protection method
CN107560757B (en) Method and system for estimating upper oil temperature of air-cooled transformer
CN103699152A (en) Power device over-temperature protection method based on temperature curve slope control
WO2018095105A1 (en) Method and device for limiting stator current utilized in automatic voltage regulator of electric generator
JP2009232610A (en) Device for protecting load circuit
US7869178B2 (en) Augmentation of ambient temperature and free convection effects in thermal circuit breaker trip curve approximations
CN113179070B (en) Dynamic protection system for power terminal of vehicle electric drive system
CN106711968B (en) Setting method and system for inverse time limit zero sequence current protection
EP2787588A2 (en) Overload prevention system to improve intermittent load capacity of electric drive applications
CN110333443B (en) Temperature rise test method for stator winding of induction motor
CN109390919B (en) Digital line protection
JP2017225254A5 (en)
CN112597672B (en) Arc temperature field calculation method for preformed armor rod port discharge phenomenon
CN102856884B (en) Heat accumulation based frequency converter overload method
CN115204000A (en) Method for calculating rated current-carrying capacity of cable based on soil thermal resistivity change
KR100945721B1 (en) Apparatus for Decreasing Inrush Current Using SFCL, and Decision Method for Optimum Resistance thereof
CN103384060A (en) Method for protecting thermal overload of alternating-current motor
CN110925231B (en) Fan failure over-temperature protection method, device and system
CN104821598A (en) Control method and control device for grid-connected inverter
CN114336524B (en) Overload trip level automatic setting method and device and motor protector

Legal Events

Date Code Title Description
PB01 Publication
PB01 Publication
SE01 Entry into force of request for substantive examination
SE01 Entry into force of request for substantive examination
GR01 Patent grant
GR01 Patent grant