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A New Differential Protection Algorithm for Two-speed Motors

A differential protection and motor technology, applied in emergency protection circuit devices, electrical components, etc., can solve the problems of insufficient braking current to meet requirements, increased CT load, workload, and high work risk.

Active Publication Date: 2020-01-24
HUADIAN ZOUXIAN POWER GENERATION CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0003] One is that the CTΔ wiring method will increase the load of the CT and easily cause CT saturation
When the CT is moderately or severely saturated, a large differential current will be generated, and the braking current may not meet the requirements, and the protection will malfunction
[0004] Second, when switching between high and low speeds, it is necessary to work at heights every time, switching the secondary circuit, the workload and work risks are relatively large

Method used

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  • A New Differential Protection Algorithm for Two-speed Motors
  • A New Differential Protection Algorithm for Two-speed Motors
  • A New Differential Protection Algorithm for Two-speed Motors

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0063] see figure 1 As shown, the present invention is a novel two-speed motor differential protection algorithm, comprising the following steps:

[0064] Step 1, select the working mode of the motor as high-speed mode or low-speed mode;

[0065] Step 2, analyze the motor switch side and neutral point side current;

[0066] Step 3, parameter setting of the protective device;

[0067] Step 4, input protection device parameters;

[0068] Step 5, verify the actual current measured on the switch side of the motor and the neutral electricity.

[0069] Such as Figure 2-3 As shown, the wiring mode of the motor in the high-speed mode is 4Y wiring, and the wiring mode of the motor in the low-speed mode is 2Δ.

[0070] Preferably, the analysis algorithm of step 2 is:

[0071] Such as Figure 4 As shown, under the high-speed 4Y wiring mode of the motor, the current relationship between the switch side and the neutral point side is:

[0072] iU=iu;

[0073] iV=iv;

[0074] iW=i...

Embodiment 2

[0095] In this invention, the RCS9622C transformer protection device of NARI Relay is used to replace the RCS9627C motor protection device to realize the Y / Δ conversion function of the motor differential protection, and the algorithm is verified. The verification process includes the following:

[0096] Such as Figure 6-7 As shown, the voltage circuit RCS9627C adopts a three-phase four-wire system, and RCS9622C adopts a three-phase three-wire system. If the RCS9627C is changed to RCS9622C, the N wire needs to be removed. The CT circuit on the neutral point side of RCS9627C corresponds to the current circuit on the low-voltage side of RCS9622C, and the CT circuit on the switch side corresponds to the current circuit on the high-voltage side. There is no difference for other circuits.

[0097] Such as Figure 8-9 As shown, in the low-voltage protection, the RCS9622C device does not have the low-voltage tripping function required by the pump, and the low-voltage protection act...

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Abstract

The invention discloses a novel double-speed motor differential protection algorithm. The algorithm comprises the following steps of step 1, selecting a working mode of a motor to be a high-speed modeor a low-speed mode; step 2, analyzing the currents of the motor on a switch side and a neutral point side; step 3, setting parameters; step 4, inputting parameters; and step 5, verifying the actualcurrents of the motor on the switch side and the neutral point side. According to the operation mode of the motor, wiring groups of the differential protection two-side currents are set in a targetedmode, the unbalanced current caused by different current amplitudes and phases on the two sides of the motor is eliminated, and the purpose of differential protection of the motor is achieved.

Description

technical field [0001] The invention belongs to the technical field of electric motor protection, in particular to a novel two-speed electric motor differential protection algorithm. Background technique [0002] When the circulating water pump is running at low speed, according to the traditional method, although the CTΔ wiring method on the neutral point side can realize the differential protection function of the motor, there are also the following problems: [0003] One is that the CTΔ wiring method will increase the load of the CT, which will easily cause CT saturation. When the CT is moderately or severely saturated, a large differential current will be generated, and the braking current may not meet the requirements, and the protection may malfunction. [0004] The second is that when switching between high and low speeds, it is necessary to work at heights every time, switching the secondary circuit, the workload and work risks are relatively large. Contents of th...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H02H7/08
CPCH02H7/08
Inventor 卜繁薇徐宝福吴建勋杜宁宁孟强林西国刘国新韩国强仲计戈
Owner HUADIAN ZOUXIAN POWER GENERATION CO LTD
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