Generator low-frequency starting process protection method and device

A low-frequency start-up and protection device technology, which is applied to emergency protection circuit devices, electrical components, parameter calibration/setting, etc., can solve the problems affecting the protection performance of the low-frequency start-up process, poor transmission characteristics, and large transmission errors. To achieve the effect of facilitating program realization, improving reliability and improving sensitivity

Active Publication Date: 2020-06-30
NR ELECTRIC CO LTD +1
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  • Claims
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AI Technical Summary

Problems solved by technology

Due to the deterioration of the transmission characteristics of conventional electromagnetic transformers as the frequency decreases, especially when the frequency is very low in the initial stage, the transformer enters deep saturation and the transmission error is large, which seriously affects the protection performance during low-frequency startup. In order to reduce the risk of protection misoperation , generally need to adopt a higher setting value, but the sensitivity is very low at the high frequency stage, so it is difficult to balance the protection sensitivity of the high frequency range and the protection reliability of the extremely low frequency range

Method used

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  • Generator low-frequency starting process protection method and device
  • Generator low-frequency starting process protection method and device
  • Generator low-frequency starting process protection method and device

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Embodiment 1

[0035] Such as figure 1 As shown, Embodiment 1 of a generator low-frequency startup process protection method according to the present invention includes:

[0036] S1: Collect the terminal side voltage of the generator.

[0037] S2: Calculate the generator terminal side voltage frequency.

[0038] S3: When the calculated frequency value of the terminal side voltage is higher than the frequency braking low frequency input setting, the original protection settings of each protection remain unchanged; when the calculated frequency value of the terminal side voltage is lower than the frequency braking When the low frequency is input to the fixed value, the original protection fixed value is increased by the corresponding multiple; the corresponding multiple calculation method is: the frequency deviation value is multiplied by the fixed value of the ratio braking coefficient. The various protections include differential protection, overcurrent protection, and zero-sequence overvo...

Embodiment 2

[0040] Embodiment 2 of a method for protecting a generator during low-frequency start-up according to the present invention includes:

[0041] S21: Collect generator terminal side voltage and current, neutral point side current and zero sequence voltage.

[0042] S22: Using an algorithm that is not affected by frequency changes, calculate the voltage frequency at the generator side, the current amplitude and differential current amplitude at the generator side and the neutral point side, and the zero-sequence voltage amplitude at the neutral point side of the generator. Among them, algorithms that are not affected by frequency changes include zero-crossing point integration algorithm or current peak value discrimination method.

[0043] S23: When the calculated frequency value of the terminal side voltage is higher than the frequency braking low frequency input setting value, keep the original protection settings of each protection unchanged; when the calculated frequency valu...

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Abstract

The invention discloses a generator low-frequency starting process protection method and device. The method comprises the steps of collecting the generator end side voltage of a generator; calculatingthe machine end side voltage frequency of the generator; when the calculated machine end side voltage frequency value is higher than a frequency braking low-frequency input constant value, keeping the original protection constant value of each protection unchanged; and when the calculated machine end side voltage frequency value is lower than the frequency braking low-frequency input constant value, increasing the original protection constant value by a corresponding multiple, wherein the corresponding multiple calculation mode is that a frequency deviation value is multiplied by a ratio braking coefficient constant value. By improving the protection constant value of the low-frequency starting process protection, the reliability of the initial extremely-low frequency stage protection inthe variable-frequency starting process of the generator can be improved, and when the frequency of the generator is higher than the set value, the protection can take a sensitive constant value to ensure the sensitivity of the protection.

Description

technical field [0001] The invention relates to the field of relay protection, in particular to a method and device for protecting a generator during low-frequency start-up based on the principle of frequency ratio braking. Background technique [0002] Due to special operating conditions, large-scale pumped storage generators, gas turbines, and new phase adjustment units generally cannot start by themselves. Usually, a static frequency converter (SFC) is used to start, gradually dragging from zero Hz to near the rated frequency, and then checking the synchronization. Grid-connected. Therefore, unlike conventional thermal power, hydropower and other units, pumped storage units, gas turbine units, and new-type capacitor units are always charged with stator and rotor windings during the start-up phase, and the frequency is a frequency conversion process from zero Hz to rated frequency. In the initial stage, the frequency is extremely high. Low. Due to the deterioration of th...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H02H7/06
CPCH02H7/06H02H3/006
Inventor 王光陈俊王凯李华忠陈佳胜郭自刚季遥遥
Owner NR ELECTRIC CO LTD
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