CN112014743A - Method for detecting battery discharge SCR short circuit of UPS - Google Patents
Method for detecting battery discharge SCR short circuit of UPS Download PDFInfo
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- 238000007599 discharging Methods 0.000 claims description 4
- 238000012545 processing Methods 0.000 claims description 3
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- 238000001514 detection method Methods 0.000 description 4
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 2
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/36—Arrangements for testing, measuring or monitoring the electrical condition of accumulators or electric batteries, e.g. capacity or state of charge [SoC]
- G01R31/382—Arrangements for monitoring battery or accumulator variables, e.g. SoC
- G01R31/3842—Arrangements for monitoring battery or accumulator variables, e.g. SoC combining voltage and current measurements
Abstract
A method for detecting battery discharge SCR short circuit of UPS aims at overcoming the defect that judgment is easy to miss when the grid voltage is low and the battery voltage is high when the battery discharge SCR short circuit fault of the UPS in the prior art is detected, and provides a method for detecting battery discharge SCR short circuit of the UPS, which comprises the following steps: A. low-pass filtering the positive and negative battery voltages; B. calculating the difference value of the positive side battery voltage filtering value and the negative side battery voltage filtering value, and executing the step C if the difference value is greater than a set voltage difference threshold value; if the difference value is smaller than the set voltage difference threshold value, no fault occurs; C. adding disturbance to cause the voltage and current change of the battery, evaluating the voltage or current of the positive-side battery and the negative-side battery, and if the value is greater than a set threshold value, determining that the SCR of the battery is in short circuit; if the value is less than the set threshold, no fault is considered to occur. The method can accurately judge the battery discharge SCR short-circuit fault when the load is small, and is suitable for detecting the battery discharge SCR short-circuit fault of the UPS.
Description
Technical Field
The invention relates to the field of UPS, in particular to a method for detecting battery discharge SCR short circuit of UPS.
Background
During normal operation of a UPS (uninterruptible power supply), a short-circuit fault of a battery discharge SCR (silicon controlled thyristor) needs to be detected, and uncontrollable charging of the battery by a mains supply or continuous discharging of the battery is prevented. These can result in the UPS system losing effective management of the battery. Thereby causing the battery to be overcharged or overdischarged, shortening the battery life, and even causing the UPS to power down.
The rectifier circuit of the UPS mostly adopts the topology shown in the following figure. The commercial power booster circuit and the battery discharge booster circuit are shared. The general detection method is to detect the voltage or current state of the battery as the criterion of the fault. However, simply based on the voltage or current state of the battery, under certain conditions, a false positive may be missed. For example, when the battery voltage is higher than the peak value of the mains voltage and the UPS load is small, the mains input SCR (silicon controlled thyristor) is cut off due to the back voltage, and a part of the energy of the capacitor on the dc bus is supplied by the battery. Under the working condition, even though the control system can calculate the turn-on time of the IGBT (insulated gate bipolar transistor) according to the power factor correction algorithm, the change of the turn-on time of the IGBT is small due to small load, so that the change of the voltage and the current of the battery cannot be caused, and the traditional identification method is invalid and fails to judge faults.
Disclosure of Invention
The invention overcomes the defects that the state of the battery voltage or current is directly detected when the battery discharge SCR short circuit fault of the UPS is detected in the prior art, and the traditional detection method is easy to lose efficacy when the grid voltage is low and the battery voltage is high, so that the judgment is missed, and provides the method for detecting the battery discharge SCR short circuit of the UPS.
The invention adopts the technical scheme that the purpose of the invention is realized by: a method of detecting a battery discharge SCR short circuit of a UPS, comprising the steps of:
A. low-pass filtering is carried out on the positive-side battery voltage and the negative-side battery voltage, and ripples at or above power frequency are filtered;
B. calculating the difference value of the positive side battery voltage filtering value and the negative side battery voltage filtering value in the step A, and executing the step C if the difference value is larger than a set voltage difference threshold value; if the difference value is smaller than the set voltage difference threshold value, no fault occurs;
C. adding disturbance to cause the voltage and current change of the battery, evaluating the voltage or current of the positive-side battery and the negative-side battery, and if the value is greater than a set threshold value, determining that the SCR of the battery is in short circuit; if the value is less than the set threshold, no fault is considered to occur.
Further, in the step a, the cut-off frequency of the low-pass filtering is less than 10 Hz; in the step B, the setting of the voltage difference threshold is determined according to the load rate of the UPS system, and when the load rate is less than 5%, the voltage difference threshold is less than 12V; when the load factor is more than 5%, the voltage difference threshold is less than 17V.
Further, in the step a, the cut-off frequency of the low-pass filtering is 1 Hz; in the step B, the setting of the voltage difference threshold is determined according to the load rate of the UPS system, and when the load rate is less than 5%, the voltage difference threshold is set to be 10V; when the load factor is greater than 5%, the voltage difference threshold is set to 15V.
Further, the step C comprises the following steps:
a. starting the charger once every a period of time, and continuously charging for a period of time;
b. c, low-pass filtering the positive and negative battery charging current in the step a to filter power frequency ripples and ripples above;
c. and c, calculating the difference value of the positive and negative battery charging current filter values in the step b, and if the difference value is larger than a set threshold value, determining that the battery discharging SCR is in short circuit.
Further, in the step a, the interval time for starting the charger is 1-10 minutes, and the charging duration time of the charger is 0.5-2 minutes; in step b, the cut-off frequency of the low-pass filtering is less than 10 Hz.
Further, in the step a, the interval time for starting the charger is 5 minutes, and the charging duration time of the charger is 1 minute; in the step b, the cut-off frequency of the low-pass filtering is 1 Hz; in step c, the threshold is 3A.
Further, the step C comprises the following steps:
a. processing the duty ratio calculated by the control loop of the booster circuit, and adding alternating current disturbance on the original basis;
b. calculating the effective values of the alternating current ripples of the positive-side battery voltage and the negative-side battery voltage in the step a;
c. and c, if the effective value of the alternating current ripple of the positive side battery voltage or the negative side battery voltage in the step b is larger than the set ripple threshold, the battery discharge SCR is considered to be in short circuit.
Further, in the step a, alternating current disturbance with frequency 5 times of power frequency and duty ratio amplitude of 3% -7% is added, the disturbance is carried out once every 1-10 minutes, and each disturbance lasts for 500-1000 ms; in the step c, the ripple threshold is 5-10V.
Further, in the step a, adding alternating current disturbance with frequency 5 times of power frequency and duty ratio amplitude of 3%, and disturbing once every 5 minutes, wherein each disturbance lasts 500 ms; in step c, the ripple threshold is 5V.
Further, in the step b, the positive side battery voltage ac ripple value = positive side battery voltage instantaneous value-positive side battery voltage filtered value, and the effective value of the positive side current voltage ac ripple value is calculated; the ac ripple value of the negative-side battery voltage = negative-side battery voltage instantaneous value — negative-side battery voltage filtered value, and the effective value of the negative-side current-voltage ac ripple value is calculated.
The invention has the beneficial effects that: the method adds disturbance in the detection process to cause the change of the battery voltage and the battery current, can accurately judge the SCR short-circuit fault of battery discharge when the load is small, effectively avoids the defect of failure and missing judgment when the power grid voltage is low and the battery voltage is high in the conventional method, and improves the accuracy of fault detection.
The invention is further described with reference to the following detailed description and accompanying drawings.
Drawings
FIG. 1 is a flow chart of the present invention.
Fig. 2 is a flow chart of a first embodiment of the present invention.
FIG. 3 is a flow chart of a second embodiment of the present invention.
Detailed Description
As shown in fig. 1, a method for detecting a short circuit of a battery discharge SCR of a UPS according to this embodiment includes the following steps:
A. low-pass filtering is carried out on the positive-side battery voltage and the negative-side battery voltage, ripples at or above the power frequency are filtered out, the cut-off frequency of the low-pass filtering is less than 10Hz, and the preferred cut-off frequency of the low-pass filtering is 1 Hz;
B. calculating the difference value of the positive side battery voltage filtering value and the negative side battery voltage filtering value in the step A, and executing the step C if the difference value is larger than a set voltage difference threshold value; if the difference value is smaller than the set voltage difference threshold value, no fault occurs; the setting of the voltage difference threshold is determined according to the load rate of the UPS system, when the load rate is less than 5%, the voltage difference threshold is less than 12V, and the voltage difference threshold is preferably set to 10V in this embodiment; when the load factor is greater than 5%, the voltage difference threshold is less than 17V, and the voltage difference threshold is preferably set to 15V in this embodiment;
C. adding disturbance to cause the voltage and current change of the battery, evaluating the voltage or current of the positive-side battery and the negative-side battery, and if the value is greater than a set threshold value, determining that the SCR of the battery is in short circuit; if the value is less than the set threshold, no fault is considered to occur.
The perturbation added to cause the voltage current change of the battery can take various forms, as shown in fig. 2, and step C of the first embodiment comprises the following steps:
a. the charger is started every 1-10 minutes and continuously charged for 0.5-2 minutes, the interval time for starting the charger is preferably 5 minutes, and the charging duration time of the charger is 1 minute;
b. c, performing low-pass filtering on the positive and negative battery charging current in the step a to filter power frequency and ripple waves above, wherein the cut-off frequency of the low-pass filtering is less than 10Hz, and the preferred cut-off frequency of the low-pass filtering is 1 Hz;
c. and c, calculating the difference value of the filter values of the charging currents of the positive and negative batteries in the step b, and if the difference value is greater than a set threshold value, determining that the battery discharging SCR is short-circuited, wherein the preferred threshold value in the embodiment is 3A.
Example one experiment was performed according to the scheme of figure 2 and preferred parameters, and the data are as follows:
when the charger was on, the battery charging current was given to be 3.5A. After the fault occurs, the negative side battery current becomes large and reaches the wave-by-wave current limiting point 13.3A of the charger. The positive-negative battery current difference is greater than 3A, so that the negative battery discharge SCR fault can be judged.
The perturbation added to cause the voltage and current change of the battery can be in various forms, as shown in fig. 3, and step C of the second embodiment comprises the following steps:
a. processing the duty ratio calculated by the control loop of the booster circuit, adding alternating current disturbance on the basis of the original condition, adding alternating current disturbance with the frequency of 5 times of the power frequency and the duty ratio amplitude of 3% -7%, and disturbing once every 1-10 minutes, wherein each disturbance lasts 500-1000 ms, the alternating current disturbance with the frequency of 5 times of the power frequency and the duty ratio amplitude of 3% is preferably added in the embodiment, and is disturbed once every 5 minutes, and each disturbance lasts 500 ms;
b. calculating the effective values of the alternating current ripple of the positive-side battery voltage and the negative-side battery voltage in the step a in a way that the effective value of the alternating current ripple of the positive-side battery voltage = the instantaneous value of the positive-side battery voltage-the filtered value of the positive-side battery voltage and the effective value of the alternating current ripple of the positive-side current voltage is calculated; the alternating ripple value of the negative-side battery voltage = negative-side battery voltage instantaneous value-negative-side battery voltage filtering value, and the effective value of the negative-side current voltage alternating ripple value is calculated;
c. and if the effective value of the alternating current ripple of the positive-side or negative-side battery voltage in the step b is greater than the set ripple threshold, considering that the battery discharge SCR is short-circuited, wherein the ripple threshold is 5-10V, and the preferred ripple threshold in the embodiment is 5V.
Example two experiments were performed according to the scheme of fig. 3 and preferred parameters, and the data are as follows:
as can be seen from the data, after the negative-side discharge SCR fails, the negative-side battery voltage ripple is greater than the set threshold value of 5V, so that it can be determined that the negative-side battery discharge SCR fails.
Claims (10)
1. A method for detecting a battery discharge SCR short circuit of a UPS is characterized by comprising the following steps:
A. low-pass filtering is carried out on the positive-side battery voltage and the negative-side battery voltage, and ripples at or above power frequency are filtered;
B. calculating the difference value of the positive side battery voltage filtering value and the negative side battery voltage filtering value in the step A, and executing the step C if the difference value is larger than a set voltage difference threshold value; if the difference value is smaller than the set voltage difference threshold value, no fault occurs;
C. adding disturbance to cause the voltage and current change of the battery, evaluating the voltage or current of the positive-side battery and the negative-side battery, and if the value is greater than a set threshold value, determining that the SCR of the battery is in short circuit; if the value is less than the set threshold, no fault is considered to occur.
2. The method of claim 1, wherein in step a, the cut-off frequency of the low-pass filter is less than 10 Hz; in the step B, the setting of the voltage difference threshold is determined according to the load rate of the UPS system, and when the load rate is less than 5%, the voltage difference threshold is less than 12V; when the load factor is more than 5%, the voltage difference threshold is less than 17V.
3. The method according to claim 2, wherein in step a, the cut-off frequency of the low-pass filter is 1 Hz; in the step B, the setting of the voltage difference threshold is determined according to the load rate of the UPS system, and when the load rate is less than 5%, the voltage difference threshold is set to be 10V; when the load factor is greater than 5%, the voltage difference threshold is set to 15V.
4. The method of claim 1, wherein step C comprises the steps of:
a. starting the charger once every a period of time, and continuously charging for a period of time;
b. c, low-pass filtering the positive and negative battery charging current in the step a to filter power frequency ripples and ripples above;
c. and c, calculating the difference value of the positive and negative battery charging current filter values in the step b, and if the difference value is larger than a set threshold value, determining that the battery discharging SCR is in short circuit.
5. The method of claim 4, wherein in the step a, the interval between the turning on of the charger is 1-10 minutes, and the charging duration of the charger is 0.5-2 minutes; in step b, the cut-off frequency of the low-pass filtering is less than 10 Hz.
6. The method as claimed in claim 5, wherein in step a, the interval between the turning on of the charger is 5 minutes, and the charging duration of the charger is 1 minute; in the step b, the cut-off frequency of the low-pass filtering is 1 Hz; in step c, the threshold is 3A.
7. The method of claim 1, wherein step C comprises the steps of:
a. processing the duty ratio calculated by the control loop of the booster circuit, and adding alternating current disturbance on the original basis;
b. calculating the effective values of the alternating current ripples of the positive-side battery voltage and the negative-side battery voltage in the step a;
c. and c, if the effective value of the alternating current ripple of the positive side battery voltage or the negative side battery voltage in the step b is larger than the set ripple threshold, the battery discharge SCR is considered to be in short circuit.
8. The method for detecting the battery discharge SCR short circuit of the UPS according to claim 7, wherein in the step a, an alternating current disturbance with the frequency of 5 times of power frequency and the duty ratio amplitude of 3% -7% is added, the disturbance is performed once every 1-10 minutes, and each disturbance lasts for 500-1000 ms; in the step c, the ripple threshold is 5-10V.
9. The method according to claim 8, wherein in step a, an ac disturbance with a frequency of 5 times the power frequency and a duty cycle amplitude of 3% is added, the disturbance is performed every 5 minutes for 500 ms; in step c, the ripple threshold is 5V.
10. The method according to claim 7, wherein in step b, the positive side battery voltage ripple value = positive side battery voltage instantaneous value-positive side battery voltage filtered value, and the effective value of the positive side current voltage ripple value is calculated; the ac ripple value of the negative-side battery voltage = negative-side battery voltage instantaneous value — negative-side battery voltage filtered value, and the effective value of the negative-side current-voltage ac ripple value is calculated.
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|---|---|---|---|---|
| US20140091783A1 (en) * | 2012-09-26 | 2014-04-03 | Canara, Inc. | System and method for monitoring ac ripple |
| CN103913664A (en) * | 2012-12-31 | 2014-07-09 | 力博特公司 | Short-circuit detection method and device |
| CN105914777A (en) * | 2016-04-15 | 2016-08-31 | 广西电网有限责任公司电力科学研究院 | MPPT-based island detection method |
| US20180172772A1 (en) * | 2016-12-16 | 2018-06-21 | Nio Nextev Limited | Online detection method for internal short-circuit of battery |
| CN109932568A (en) * | 2019-04-19 | 2019-06-25 | 重庆大学 | The measurement method of gird-connected inverter impedance |
| CN110719043A (en) * | 2019-11-21 | 2020-01-21 | 深圳国能电气有限公司 | Inverter harmonic compensation method and control device thereof |
-
2020
- 2020-09-08 CN CN202010933017.8A patent/CN112014743A/en active Pending
Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20140091783A1 (en) * | 2012-09-26 | 2014-04-03 | Canara, Inc. | System and method for monitoring ac ripple |
| CN103913664A (en) * | 2012-12-31 | 2014-07-09 | 力博特公司 | Short-circuit detection method and device |
| CN105914777A (en) * | 2016-04-15 | 2016-08-31 | 广西电网有限责任公司电力科学研究院 | MPPT-based island detection method |
| US20180172772A1 (en) * | 2016-12-16 | 2018-06-21 | Nio Nextev Limited | Online detection method for internal short-circuit of battery |
| CN109932568A (en) * | 2019-04-19 | 2019-06-25 | 重庆大学 | The measurement method of gird-connected inverter impedance |
| CN110719043A (en) * | 2019-11-21 | 2020-01-21 | 深圳国能电气有限公司 | Inverter harmonic compensation method and control device thereof |
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