CN-121978515-A - Direct current system switch state intelligent detection system based on multiple spot current sampling

CN121978515ACN 121978515 ACN121978515 ACN 121978515ACN-121978515-A

Abstract

The invention discloses a direct current system switch state intelligent detection system based on multipoint current sampling, which comprises a current sampling unit, a signal conditioning and collecting unit and a signal conditioning and collecting unit, wherein the current sampling unit is used for collecting current data of a main circuit of a direct current system bus switch, the current sampling unit comprises a micro current sensor array which is arranged at an input end P1, an internal contact position P2 and an output end P3 of the bus switch and is used for respectively detecting real-time current values of two sides and a middle node of the switch, and the signal conditioning and collecting unit is connected with the current sampling unit. Even if the auxiliary contact fails, the system can accurately identify the switch state based on the real distribution of the main loop current, and the dependence on the auxiliary contact is thoroughly eliminated.

Inventors

YU TAO
HE LITING
CHEN YAFEI
ZHANG LIN
DUAN XIANGYUE
GAN MING
JIANG JIANAN
HOU YANKUN
ZHAO JIANSONG
Shang Maolin
ZHOU CHAO
ZHENG YIQIN
CHEN JUN
ZHENG XU
LIAO WEI
WANG LINGJIE
HE YUANFU
LIU YANG
WU YUZHU
LI TINGTING
WANG XIAN
FU HANG
TANG GUANGHUA
CAI XINYA
YU XINFU

Assignees

贵州电网有限责任公司

Dates

Publication Date: 20260505
Application Date: 20251219

Claims (10)

1. The intelligent detection system for the switch state of the direct current system based on multipoint current sampling is characterized by comprising a current sampling unit, a signal conditioning and collecting unit, a main control processing unit and a signal conditioning and collecting unit, wherein the current sampling unit is used for collecting current data of a main loop of a direct current system bus switch, the current sampling unit comprises a micro current sensor array which is arranged at an input end P1, an internal contact position P2 and an output end P3 of the bus switch and is used for respectively detecting real-time current values of two sides and a middle node of the switch, the signal conditioning and collecting unit is connected with the current sampling unit and is used for conducting filtering processing and analog-to-digital conversion on collected current signals, and the main control processing unit is connected with the signal conditioning and collecting unit and is configured to acquire current data of all sampling points, and judge the actual on or off state of the bus switch by calculating current difference characteristics and current correlation characteristics among adjacent sampling points and combining preset state judging logic.
2. The intelligent detection system for the switch state of the direct current system based on the multipoint current sampling as claimed in claim 1, wherein the sensor of the input end P1 is arranged at a joint connecting the first storage battery pack to the input end of the bus switch, the sensor of the output end P3 is arranged at a joint connecting the output end of the bus switch to the second storage battery pack, the sensor of the internal contact point position P2 is arranged near an internal contact point of the switch, the three sampling points are in serial connection in space topology, and the sensors in the micro-current sensor array adopt Hall current sensors.
3. The intelligent detection system for the switch state of the direct current system based on the multipoint current sampling as claimed in claim 2, further comprising a threshold self-adapting unit, wherein the threshold self-adapting unit is used for dynamically adjusting a judging threshold in the state judging logic, identifying the capacity grade of the direct current system according to the monitored floating charge flow average value when the device is started, initializing a current difference threshold and a correlation coefficient threshold according to the capacity grade, counting the current difference component distribution characteristics in a history normal closed state in the running process of the device, calculating the average value and standard deviation of the current difference component distribution characteristics, and updating the dynamic current difference threshold in real time.
4. The intelligent detection system for switch states of a direct current system based on multipoint current sampling according to claim 3, wherein the main control processing unit is used for calculating a first current difference component DeltaI 12 between an input end P1 and an internal contact point position P2 and a second current difference component DeltaI 23 between the internal contact point position P2 and an output end P3 when extracting features, calculating a first pearson correlation coefficient r 12 between the input end P1 and the internal contact point position P2 in a set time window and a second pearson correlation coefficient r 23; between the internal contact point position P2 and the output end P3, wherein the state judgment logic is used for judging that the switch is closed when the current difference component is smaller than a dynamic current difference threshold and the correlation coefficient is larger than the correlation coefficient value, and judging that the switch is opened when the current difference component is larger than the dynamic current difference threshold or the correlation coefficient is smaller than the correlation coefficient value.
5. The intelligent detection system for the switch state of the direct current system based on the multipoint current sampling as claimed in claim 4, wherein the threshold self-adaptive unit further comprises a temperature compensation module, a temperature sensor is arranged in the device, the temperature compensation module corrects the current differential threshold by utilizing a temperature coefficient according to the collected ambient temperature, and the reference temperature is set to be 25 ℃.
6. The intelligent detection system for the switch state of the direct current system based on multipoint current sampling according to claim 5, further comprising an insulation monitoring unit and a transfer switch unit, wherein the current sampling unit further comprises feeder current sensors F1 to Fn installed at the outgoing ends of all direct current feeder lines, the insulation monitoring unit adopts an alternating current injection method to inject low-frequency alternating current signals into direct current buses and detects alternating current response currents of all feeder lines through the feeder current sensors to calculate insulation resistance to ground, the transfer switch unit comprises a main bus switch group and a standby bus switch group, and when the main control processing unit receives a signal that the insulation resistance of a certain feeder line is lower than an alarm threshold value, the transfer switch unit is controlled to seamlessly switch the fault feeder line from the main bus to the standby bus.
7. The intelligent detection system for the switch state of the direct current system based on the multipoint current sampling as claimed in claim 6, wherein the main control processing unit is further configured to execute a direct current loop detection function, collect output currents of two groups of storage batteries and load currents of all feeder lines, calculate a difference value between the total output currents of the storage batteries and the total load currents of the feeder lines, determine that a loop exists in the system when the absolute value of the difference value continuously exceeds a loop judgment threshold value, and locate a loop path by combining current direction information of an internal contact point position P2 of the bus switch.
8. The intelligent detection system for the switch state of the direct current system based on the multipoint current sampling as set forth in claim 7, wherein the main control processing unit is further provided with a state confirmation delay mechanism, when the switch state is detected to change, the preset time length is continuously observed, and the switch state output is confirmed and updated only when the judging results of all sampling points within the time period are consistent, so that transient interference is filtered.
9. The intelligent detection system for the switch state of the direct current system based on the multipoint current sampling as claimed in claim 8, wherein the signal conditioning and collecting unit performs first-order low-pass filtering processing on each channel signal, the filter cutoff frequency is set to be 100Hz for attenuating high-frequency noise interference, and the sampling frequency of the current sampling unit is set to be 1kHz.
10. The intelligent detection system for the switch state of the direct current system based on the multipoint current sampling as claimed in claim 9, further comprising a display alarm unit, wherein the display alarm unit adopts a TFT touch screen to identify the switch on/off and the state to be confirmed by different colors, and the alarm function is divided into three levels of information level, alarm level and fault level, and the three levels correspond to different display colors and acousto-optic prompt strategies respectively.

Description

Direct current system switch state intelligent detection system based on multiple spot current sampling Technical Field The invention relates to the field of switch state detection of a direct current system, in particular to an intelligent switch state detection system of the direct current system based on multipoint current sampling. Background The direct current system of the transformer substation is an important infrastructure for guaranteeing safe and stable operation of the power system, and reliable operation of the direct current system is directly related to normal operation of secondary equipment such as protection, control and signals in the transformer substation. However, the existing dc system switch state detection technology mainly has the following disadvantages: The traditional direct current system switch state detection mainly relies on auxiliary contact signals for judgment, and the method has inherent defects. The auxiliary contact is mechanically independent from the main contact, and when the main contact fails due to poor contact, ablation, spring fatigue and the like, the auxiliary contact can still be normally closed, so that the control system misjudges the actual state of the switch. The existing part detection device adopts a single-point current detection method, a current sensor is arranged on one side of a bus-tie switch, and the state of the switch is judged by detecting through current. However, this method is susceptible to disturbance by factors such as circulation, charging current, load fluctuations, etc. When the storage battery pack is uniformly charged or is in floating charge, even if the bus-tie switch is opened, current still flows in the charging loop, and single-point detection cannot distinguish whether the current is normal charging current or circulation after the bus-tie switch is closed. The conventional detection device generally adopts a fixed threshold criterion, and cannot adapt to detection requirements under different capacity levels and different operation conditions. The rated voltage of the direct current system is of different grades such as 110V, 220V and the like, the capacity of the storage battery is different from hundreds of ampere hours to thousands of ampere hours, and the range span of the rated current of the switch is large. The unified current threshold is adopted for state judgment, so that the sensitivity is insufficient for a large-capacity system, and the sensitivity is too sensitive for a small-capacity system. Meanwhile, the internal resistance characteristics of the storage battery in different charge and discharge states and different environmental temperatures are obviously different, and the fixed threshold cannot be dynamically adjusted along with the changes. The existing detection device lacks the capability of monitoring the insulation state and loop faults of the direct current system. When the direct current system has a grounding fault, a fault loop cannot be positioned, and operation and maintenance personnel need to disconnect the feeder line one by one for checking, so that large-area load is lost, and the reliability of the system is affected. Meanwhile, the possible circulation problem in the direct current system cannot be effectively identified, so that the storage battery pack is unevenly discharged, and the service life is shortened. Disclosure of Invention Therefore, the technical problem to be solved by the invention is that the existing switch state detection technology of the direct current system is insufficient. The intelligent detection system for the switch state of the direct current system based on multipoint current sampling comprises a current sampling unit, a signal conditioning and collecting unit, a main control processing unit and a main control processing unit, wherein the current sampling unit is used for collecting current data of a main loop of a direct current system bus switch, the current sampling unit comprises a micro-current sensor array which is arranged at an input end P1, an internal contact position P2 and an output end P3 of the bus switch and is used for respectively detecting real-time current values of two sides and a middle node of the switch, the signal conditioning and collecting unit is connected with the current sampling unit and is used for conducting filtering processing and analog-to-digital conversion on collected current signals, the main control processing unit is connected with the signal conditioning and collecting unit and is configured to acquire the current data of each sampling point, and the actual on or off state of the bus switch is judged by calculating current difference characteristics and current correlation characteristics between adjacent sampling points and combining preset state judgment logic. The sensor of the input end P1 is arranged at the joint of the first storage battery pack and the input end of the bus-bar switch, the sensor of the output