A ground resistance measuring device and method

Abstract

The present invention discloses a grounding resistance measuring device and method, the grounding resistance measuring device comprises a voltage signal output module, a voltage signal detection module, a charge-discharge detection module and a grounding resistance measuring module; the voltage signal output module is connected with the voltage signal detection module and the charge-discharge detection module, the voltage signal output module is used to output a voltage signal to the grounding resistance after receiving a trigger signal and send a first signal to the voltage signal detection module and the charge-discharge detection module; the voltage signal detection module is connected with the grounding resistance measuring module, the voltage signal detection module is used to detect the rate of change of the voltage signal after receiving the first signal, and send a second signal to the grounding resistance measuring module when the rate of change is detected to be less than a preset rate of change. The present invention provides a grounding resistance measuring device and method, which can not only improve the accuracy of grounding resistance value measurement, but also save measurement time and improve measurement efficiency.

Description

Technical Field

[0001] The invention relates to the technical field of three-machine brushless excitation, and in particular to a ground resistance measuring device and method. Background Art

[0002] As one of the current mainstream excitation methods, the three-machine brushless excitation system is widely used. The three-machine brushless excitation system needs to be equipped with a generator and exciter magnetic field grounding detection device to detect the grounding resistance value of the generator and exciter magnetic field loop.

[0003] By monitoring the grounding resistance value of the magnetic field circuit of the generator and the exciter, the rotor grounding fault can be detected in time. Rotor grounding fault is a common fault of the generator and the exciter. When the rotor is grounded at one point, since no closed path is formed and the rotor winding parameters are not changed, it does not cause direct danger. However, if a second grounding fault occurs, the fault point current will be too large and burn the rotor body, the rotor winding will be short-circuited, causing the air gap magnetic flux to lose balance and cause vibration, and the shaft system rotor will be magnetized. Other catastrophic consequences seriously threaten the safety of the generator and the exciter. Therefore, equipping the generator and the exciter with a complete magnetic field grounding detection device and monitoring the grounding resistance value can ensure the normal operation of the generator and the exciter.

[0004] The magnetic field grounding detection device currently used in the field has a large deviation between the measured value and the actual value in actual use due to the influence of the distributed capacitance of the rotor winding to the ground. For large units, there is a distributed capacitance between the rotor winding and the ground, and the size of the distributed capacitance varies to a certain extent. If the voltage signal cannot avoid the charging and discharging process of the distributed capacitance when it is injected into the measurement loop for sampling, the collected data is transient data, and the calculation result of the grounding resistance is inaccurate. Summary of the invention

[0005] The present invention provides a grounding resistance measuring device and method, which can not only improve the accuracy of grounding resistance value measurement, but also save measurement time and improve measurement efficiency.

[0006] According to one aspect of the present invention, a ground resistance measuring device is provided, the ground resistance measuring device comprising a voltage signal output module, a voltage signal detection module, a charge and discharge detection module and a ground resistance measuring module;

[0007] The voltage signal output module is connected to the voltage signal detection module and the charge and discharge detection module, and the voltage signal output module is used to output a voltage signal to the grounding resistor after receiving a trigger signal and send a first signal to the voltage signal detection module and the charge and discharge detection module;

[0008] The voltage signal detection module is connected to the ground resistance measurement module, and the voltage signal detection module is used to detect the change rate of the voltage signal after receiving the first signal, and send a second signal to the ground resistance measurement module when it is detected that the change rate is less than a preset change rate;

[0009] The charge and discharge detection module is connected to the ground resistance measurement module, and the charge and discharge detection module is used to detect whether the distributed capacitance is charged or discharged after receiving the first signal, and send a third signal to the ground resistance measurement module when it is detected that the distributed capacitance is charged or discharged;

[0010] The grounding resistance measuring module is connected to the voltage signal output module, and is used for collecting the voltage signal in the grounding resistance and outputting the grounding resistance value when the third signal is received while the second signal is received.

[0011] Optionally, the voltage signal detection module includes a preset change rate input unit and a voltage signal detection unit;

[0012] The preset change rate input unit is connected to the voltage signal detection unit, and the preset change rate input unit is used to receive the preset change rate input by the user and send the preset change rate to the voltage signal detection unit;

[0013] The voltage signal detection unit is connected to the voltage signal output module and the ground resistance measurement module. The voltage signal detection unit is used to detect the change rate of the voltage signal after receiving the first signal, and send the second signal to the ground resistance measurement module when it is detected that the change rate is less than the preset change rate.

[0014] Optionally, the charge and discharge detection module includes a time input unit and a timing control unit;

[0015] The time input unit is connected to the timing control unit, and the time input unit is used to receive a preset time value input by a user and send the preset time value to the timing control unit;

[0016] The timing control unit is connected to the voltage signal output module and the ground resistance measurement module. The timing control unit is used to start timing when the distributed capacitance starts to charge or discharge after receiving the first signal, and send the third signal to the ground resistance measurement module until the timing duration is equal to the preset time value.

[0017] Optionally, the ground resistance measuring device provided in this embodiment further includes an alarm module;

[0018] The alarm module is connected to the ground resistance measurement module, and the ground resistance measurement module is also used to send a fourth signal to the alarm module when the second signal is not received while the third signal is received. The alarm module is used to issue a first alarm prompt when the fourth signal is received.

[0019] Optionally, the ground resistance measuring device provided in this embodiment further includes a ground resistance value inspection module and a display module;

[0020] The grounding resistance value inspection module is connected to the grounding resistance measurement module and the display module, and the grounding resistance value inspection module is used to obtain a preset number of grounding resistance values ​​from the grounding resistance measurement module and inspect whether the preset number of grounding resistance values ​​meet the set conditions, and when the preset number of grounding resistance values ​​meet the set conditions, output the average value of the preset number of grounding resistance values ​​to the display module, wherein the preset number is a positive integer greater than 1;

[0021] The display module is used to display the average value.

[0022] Optionally, the ground resistance value inspection module includes a tolerance inspection unit, a measurement number inspection unit and a pre-value inspection unit;

[0023] The tolerance inspection unit is connected to the ground resistance measurement module, the measurement number inspection unit and the pre-value inspection unit, and the tolerance inspection unit is used to obtain the preset number of ground resistance values ​​from the ground resistance measurement module and output the average value of the preset number of ground resistance values ​​to the pre-value inspection unit when it is checked that the difference between the preset number of ground resistance values ​​is less than the set threshold value, and is also used to send a fifth signal to the measurement number inspection unit when it is checked that the difference between the preset number of ground resistance values ​​is not less than the set threshold value;

[0024] The pre-value checking unit is used for outputting the average value to the display module when checking that the average value is greater than the preset ground resistance value;

[0025] The measurement number verification unit is connected to the voltage signal output module, and is used to verify the number of times the voltage signal output module receives the trigger signal when receiving the fifth signal, and send a trigger signal to the voltage signal output module when it is verified that the number is less than a preset number.

[0026] Optionally, the ground resistance value inspection module further includes a first alarm unit and a second alarm unit;

[0027] The first alarm unit is connected to the pre-value checking unit, and the pre-value checking unit is further used to send a sixth signal to the first alarm unit when it is checked that the average value is not greater than the preset grounding resistance value, and the first alarm unit is used to issue a second alarm prompt when receiving the sixth signal;

[0028] The second alarm unit is connected to the measurement number verification unit, and the measurement number verification unit is also used to send a seventh signal to the second alarm unit when it is verified that the number value is not less than the preset number value, and the second alarm unit issues a third alarm prompt when receiving the seventh signal.

[0029] Optionally, the tolerance checking unit is connected to the display module, and the measurement times checking unit is further used to control the tolerance checking unit to directly send the average value to the display module when it is checked that the times value is not less than the preset times value.

[0030] Optionally, the ground resistance measurement device provided in this embodiment further includes a trigger signal output module;

[0031] The trigger signal output module is connected to the voltage signal output module, and the trigger signal output module is used to receive a trigger instruction and send a trigger signal to the voltage signal output module after receiving the trigger instruction.

[0032] According to another aspect of the present invention, a ground resistance measurement method is provided, wherein a voltage signal output module is connected to a voltage signal detection module and a charge and discharge detection module; the voltage signal detection module is connected to a ground resistance measurement module; the charge and discharge detection module is connected to the ground resistance measurement module; the ground resistance measurement module is connected to the voltage signal output module;

[0033] The ground resistance measurement method comprises:

[0034] The voltage signal output module outputs a voltage signal to the grounding resistor after receiving the trigger signal and sends a first signal to the voltage signal detection module and the charge and discharge detection module;

[0035] The voltage signal detection module detects the change rate of the voltage signal after receiving the first signal, and sends a second signal to the ground resistance measurement module when detecting that the change rate is less than a preset change rate;

[0036] The charge and discharge detection module detects whether the distributed capacitance is fully charged or fully discharged after receiving the first signal, and sends a third signal to the ground resistance measurement module when it is detected that the distributed capacitance is fully charged or fully discharged;

[0037] When the grounding resistance measuring module receives the third signal while receiving the second signal, it collects the voltage signal in the grounding resistance and outputs the grounding resistance value.

[0038] The present embodiment provides a grounding resistance measuring device, in which a voltage signal output module in the grounding resistance measuring device outputs a voltage signal to the grounding resistance after receiving a trigger signal, and sends a first signal to a voltage signal detection module and a charge and discharge detection module at the same time. After receiving the first signal, the voltage signal detection module detects the rate of change of the voltage signal, and sends a second signal to the grounding resistance measuring module when the rate of change of the voltage signal is less than a preset rate of change. After receiving the first signal, the charge and discharge detection module starts to detect whether the charging and discharging of the distributed capacitance is completed, and sends a third signal to the grounding resistance measuring module when the charging or discharging of the distributed capacitance is completed. When the grounding resistance measuring module receives the third signal and the second signal at the same time, it collects the voltage signals at both ends of the grounding resistance and outputs the grounding resistance value. The grounding resistance measuring module receives the second signal at the same time as the third signal, indicating that the rate of change of the voltage signal is relatively stable and is not affected by the charging and discharging of the distributed capacitance, thereby making the output grounding resistance value more accurate. The grounding resistance measuring module measures the grounding resistance value when it receives the second signal at the same time as the third signal, thereby saving measurement time and improving measurement efficiency. The grounding resistance measuring device provided in the present embodiment can not only improve the accuracy of the grounding resistance value measurement, but also save measurement time and improve measurement efficiency.

[0039] It should be understood that the contents described in this section are not intended to identify the key or important features of the embodiments of the present invention, nor are they intended to limit the scope of the present invention. Other features of the present invention will become easily understood through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0041] Figure 1 is a schematic structural diagram of a ground resistance measuring device provided according to an embodiment of the present invention;

[0042] Figure 2 is a structural schematic diagram of another ground resistance measuring device provided according to an embodiment of the present invention;

[0043] Figure 3 is a structural schematic diagram of another ground resistance measuring device provided according to an embodiment of the present invention;

[0044] Figure 4 is a structural schematic diagram of another ground resistance measuring device provided according to an embodiment of the present invention;

[0045] Figure 5 is a structural schematic diagram of another ground resistance measuring device provided according to an embodiment of the present invention;

[0046] Figure 6 is a structural schematic diagram of another ground resistance measuring device provided according to an embodiment of the present invention;

[0047] Figure 7 is a structural schematic diagram of another ground resistance measuring device provided according to an embodiment of the present invention;

[0048] Figure 8 is a structural schematic diagram of another ground resistance measuring device provided according to an embodiment of the present invention;

[0049] Fig. 9 It is a flowchart of a ground resistance measurement method provided according to an embodiment of the present invention. DETAILED DESCRIPTION

[0050] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0051] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0052] Figure 1 is a schematic diagram of the structure of a ground resistance measuring device provided according to an embodiment of the present invention, with reference to Figure 1The ground resistance measuring device provided in this embodiment includes a voltage signal output module 110, a voltage signal detection module 120, a charge and discharge detection module 130 and a ground resistance measuring module 140; the voltage signal output module 110 is connected to the voltage signal detection module 120 and the charge and discharge detection module 130, and the voltage signal output module 110 is used to output a voltage signal to the ground resistance after receiving a trigger signal and send a first signal to the voltage signal detection module 120 and the charge and discharge detection module 130; the voltage signal detection module 120 is connected to the ground resistance measuring module 140, and the voltage signal detection module 120 is used to detect the change of the voltage signal after receiving the first signal. The charge and discharge detection module 130 is connected to the grounding resistance measurement module 140, and the charge and discharge detection module 130 is used to detect whether the distributed capacitance is charged or discharged after receiving the first signal, and send a third signal to the grounding resistance measurement module 140 when it is detected that the distributed capacitance is charged or discharged; the grounding resistance measurement module 140 is connected to the voltage signal output module 110, and the grounding resistance measurement module 140 is used to collect the voltage signal in the grounding resistance and output the grounding resistance value when the third signal is received while the second signal is received.

[0053] Specifically, the voltage signal output module 110 outputs a voltage signal to the grounding resistor each time it receives a trigger signal, and sends a first signal to the voltage signal detection module 120 and the charge and discharge detection module 130. After receiving the first signal, the voltage signal detection module 120 can detect the rate of change of the voltage signal every 5 ms. When the rate of change of the voltage signal is less than the preset rate of change, it means that the current voltage signal is relatively stable, and the accuracy of the grounding resistance value measured using a stable voltage signal is higher. If the distributed capacitor collects the voltage signal at both ends of the grounding resistor during charging and discharging, the grounding resistance value obtained according to the voltage signal is affected by the charging and discharging of the distributed capacitor and has deviations. The grounding resistance measurement device provided in this embodiment can measure the grounding resistance when the distributed capacitor is fully charged or discharged, which can avoid the measured grounding resistance value being affected by the charging and discharging of the distributed capacitor. The grounding resistance measurement module 140 collects the voltage signal at both ends of the grounding resistance when receiving the third signal while receiving the second signal, that is, the voltage signal is used to measure the grounding resistance value when the output voltage signal is stable and the distributed capacitance is fully charged or discharged. There is no need to measure the grounding resistance value again after a period of time after the output voltage signal is stable and the distributed capacitance is fully charged or discharged, thereby making the measured grounding resistance value more accurate, saving measurement time, and improving measurement efficiency. The grounding resistance measurement module 140 can collect the current signal on the grounding resistance when collecting the voltage signal at both ends of the grounding resistance, obtain the grounding resistance value according to Ohm's law, and output the grounding resistance value.

[0054] The present embodiment provides a grounding resistance measuring device, in which a voltage signal output module in the grounding resistance measuring device outputs a voltage signal to the grounding resistance after receiving a trigger signal, and sends a first signal to a voltage signal detection module and a charge and discharge detection module at the same time. After receiving the first signal, the voltage signal detection module detects the rate of change of the voltage signal, and sends a second signal to the grounding resistance measuring module when the rate of change of the voltage signal is less than a preset rate of change. After receiving the first signal, the charge and discharge detection module starts to detect whether the charging and discharging of the distributed capacitance is completed, and sends a third signal to the grounding resistance measuring module when the charging or discharging of the distributed capacitance is completed. When the grounding resistance measuring module receives the third signal and the second signal at the same time, it collects the voltage signals at both ends of the grounding resistance and outputs the grounding resistance value. The grounding resistance measuring module receives the second signal at the same time as the third signal, indicating that the rate of change of the voltage signal is relatively stable and is not affected by the charging and discharging of the distributed capacitance, thereby making the output grounding resistance value more accurate. The grounding resistance measuring module measures the grounding resistance value when it receives the second signal at the same time as the third signal, thereby saving measurement time and improving measurement efficiency. The grounding resistance measuring device provided in the present embodiment can not only improve the accuracy of the grounding resistance value measurement, but also save measurement time and improve measurement efficiency.

[0055] Optional, Figure 2 is a schematic diagram of the structure of another ground resistance measuring device provided according to an embodiment of the present invention, referring to Figure 2 The voltage signal detection module 120 includes a preset change rate input unit 121 and a voltage signal detection unit 122; the preset change rate input unit 121 is connected to the voltage signal detection unit 122, and the preset change rate input unit 121 is used to receive the preset change rate input by the user and send the preset change rate to the voltage signal detection unit 122; the voltage signal detection unit 122 is connected to the voltage signal output module 110 and the ground resistance measurement module 140, and the voltage signal detection unit 122 is used to detect the change rate of the voltage signal after receiving the first signal, and send a second signal to the ground resistance measurement module 140 when it is detected that the change rate is less than the preset change rate.

[0056] Specifically, the three-machine brushless excitation system may cause disturbances to the voltage signal after changing the operation mode, causing the voltage signal to increase or decrease, but the increase or decrease of the voltage signal does not affect the measurement of the grounding resistance value. Therefore, the preset change rate input unit 121 can be set to dynamically adjust the preset change rate according to the operation mode of the three-machine brushless excitation system, so that the voltage signal can avoid external disturbances. Exemplarily, a<b<c<d is set, and the three-machine brushless excitation system is set to operate in the first operation mode, and the preset change rate is set to b. If the three-machine brushless excitation system does not disturb the voltage signal when operating in the first operation mode, and the magnitude of the voltage signal is detected to be a, a<b, then the grounding resistance value can be measured when the distributed capacitance is charged or discharged. However, when the three-machine brushless excitation system switches to the second operation mode and the second operation mode disturbs the voltage signal, causing the voltage signal to become c, if the preset change rate is still b, the grounding resistance value cannot be measured. If the preset change rate is changed to d, the grounding resistance can be measured. Therefore, setting the preset change rate input unit 121 can dynamically adjust the preset change rate when the three-machine brushless excitation system is in different operating modes, so as to ensure that the ground resistance measuring device can measure the ground resistance value when the three-machine brushless excitation system is in different operating modes, thereby improving the versatility of the ground resistance measuring device.

[0057] Optional, Figure 3 is a schematic diagram of the structure of another ground resistance measuring device provided according to an embodiment of the present invention, referring to Figure 3 The charge and discharge detection module 130 includes a time input unit 131 and a timing control unit 132; the time input unit 131 is connected to the timing control unit 132, and the time input unit 131 is used to receive a preset time value input by a user and send the preset time value to the timing control unit 132; the timing control unit 132 is connected to the voltage signal output module 110 and the ground resistance measurement module 140, and the timing control unit 132 is used to start timing when the distributed capacitance starts to charge or discharge after receiving the first signal, and send a third signal to the ground resistance measurement module 140 when the timing duration is equal to the preset time value.

[0058] Specifically, the charging and discharging time of different distributed capacitors is different. The setting of the time input unit 131 allows the user to input different preset time values ​​according to different distributed capacitors. The charging time and the discharging time of the distributed capacitors may be different. Therefore, the preset time value may include a charging preset value and a discharging preset value. The timing control unit 132 can detect when the distributed capacitor starts to charge and when it starts to discharge. When the charging time and the discharging time of the distributed capacitor are different, the timing control unit 132 starts the timing when it detects that the distributed capacitor starts to charge, and finally uses the timing duration to compare with the charging preset value. The timing control unit 132 starts the timing when it detects that the distributed capacitor starts to discharge, and finally uses the timing duration to compare with the discharge preset value. When the timing duration is equal to the preset time value, it means that the distributed capacitor has just finished charging or discharging. At this time, the timing control unit 132 sends a third signal to the ground resistance measurement module 140.

[0059] Optional, Figure 4 is a schematic diagram of the structure of another ground resistance measuring device provided according to an embodiment of the present invention, referring to Figure 4 The ground resistance measuring device provided in this embodiment also includes an alarm module 150; the alarm module 150 is connected to the ground resistance measuring module 140, and the ground resistance measuring module 140 is also used to send a fourth signal to the alarm module 150 when the third signal is received but the second signal is not received, and the alarm module 150 is used to issue a first alarm prompt when the fourth signal is received.

[0060] Specifically, when the ground resistance measurement module 140 detects that the charging or discharging of the distributed capacitance is completed, if the rate of change of the voltage signal is not detected to be less than the preset rate of change, it means that the voltage signal output module 110 or other components have failed. In this case, the alarm module 150 needs to issue a first alarm prompt to remind the staff to find the cause of the fault in time.

[0061] Optional, Figure 5 is a schematic diagram of the structure of another ground resistance measuring device provided according to an embodiment of the present invention, referring to Figure 5 The grounding resistance measuring device provided in this embodiment also includes a grounding resistance value checking module 160 and a display module 170; the grounding resistance value checking module 160 is connected to the grounding resistance measuring module 140 and the display module 170, and the grounding resistance value checking module 160 is used to obtain a preset number of grounding resistance values ​​from the grounding resistance measuring module 140 and check whether the preset number of grounding resistance values ​​meet the set conditions, and when the preset number of grounding resistance values ​​meet the set conditions, output the average value of the preset number of grounding resistance values ​​to the display module 170, wherein the preset number is a positive integer greater than 1; the display module 170 is used to display the average value.

[0062] Specifically, compared to measuring one grounding resistance value, measuring multiple grounding resistance values ​​can avoid the contingency of measurement. The setting condition is used to determine whether a preset number of grounding resistance values ​​are all qualified. If the preset number of grounding resistance values ​​are all qualified, the average value of the preset number of grounding resistance values ​​is output, and the average value is used as the final measured grounding resistance value, which can reduce the measurement error and improve the measurement accuracy. The display module 170 displays the average value, which is convenient for the user to intuitively view the measured grounding resistance value.

[0063] Optional, Figure 6 is a schematic diagram of the structure of another ground resistance measuring device provided according to an embodiment of the present invention, referring to Figure 6 The grounding resistance value inspection module 160 includes a tolerance inspection unit 161, a measurement number inspection unit 162 and a pre-value inspection unit 163; the tolerance inspection unit 161 is connected to the grounding resistance measurement module 140, the measurement number inspection unit 162 and the pre-value inspection unit 163, the tolerance inspection unit 161 is used to obtain a preset number of grounding resistance values ​​from the grounding resistance measurement module 140 and output the average value of the preset number of grounding resistance values ​​to the pre-value inspection unit 163 when the difference between the preset number of grounding resistance values ​​is less than the set threshold, and is also used to send a fifth signal to the measurement number inspection unit 162 when the difference between the preset number of grounding resistance values ​​is not less than the set threshold; the pre-value inspection unit 163 is used to output the average value to the display module 170 when the average value is greater than the preset grounding resistance value; the measurement number inspection unit 162 is connected to the voltage signal output module 110, and the measurement number inspection unit 162 is used to inspect the number of times the voltage signal output module 110 receives the trigger signal when receiving the fifth signal, and send a trigger signal to the voltage signal output module 110 when the number value is less than the preset number value.

[0064] Specifically, in the process that the tolerance inspection unit 161 obtains the preset number of grounding resistance values ​​from the grounding resistance measurement module 140, the voltage signal output module 110 or the grounding resistance measurement module 140 may fail, resulting in at least one of the preset number of grounding resistance values ​​being too large or too small, that is, the preset number of grounding resistance values ​​is unstable. Therefore, the tolerance inspection unit 161 is required to inspect whether the difference between the preset number of grounding resistance values ​​is less than a predetermined threshold value. If it is less than, it means that the difference between the preset number of grounding resistance values ​​is small, and the average value is output to the pre-value inspection unit 163. If it is not less than, it means that the difference between the preset number of grounding resistance values ​​is large, and it is necessary to send a trigger signal to the voltage signal output module 110 to re-measure the preset number of grounding resistance values. Before re-measuring, the measurement number inspection unit 162 needs to detect whether the measurement number is less than the preset number value. If it is less than, it means that re-measurement is possible, and the preset number value is a positive integer greater than 1. If a short circuit occurs at both ends of the grounding resistor, the measured grounding resistance value will be relatively small. If the average value is greater than the preset grounding resistance value, it means that the two ends of the grounding resistor are not short-circuited, and the average value is output to the display module 170. Therefore, setting the pre-value verification unit 163 to verify the size between the average value and the preset grounding resistance value can detect whether a short circuit occurs at both ends of the grounding resistor.

[0065] Optional, Figure 7 is a schematic diagram of the structure of another ground resistance measuring device provided according to an embodiment of the present invention, referring to Figure 7 The grounding resistance value inspection module 160 also includes a first alarm unit 164 and a second alarm unit 165; the first alarm unit 164 is connected to the pre-value inspection unit 163, and the pre-value inspection unit 163 is also used to send a sixth signal to the first alarm unit 164 when the average value is not greater than the preset grounding resistance value, and the first alarm unit 164 is used to issue a second alarm prompt when receiving the sixth signal; the second alarm unit 165 is connected to the measurement number inspection unit 162, and the measurement number inspection unit 162 is also used to send a seventh signal to the second alarm unit 165 when the number value is not less than the preset number value, and the second alarm unit 165 issues a third alarm prompt when receiving the seventh signal.

[0066] Specifically, when the average value is not greater than the preset grounding resistance value, it may indicate that a short circuit occurs at both ends of the grounding resistance. Therefore, the pre-value verification unit 163 sends a sixth signal to the first alarm unit 164 when the average value is not greater than the preset grounding resistance value, so that the first alarm unit 164 issues a second alarm prompt to prompt the staff to promptly check the abnormal cause. The preset number of times can be set according to actual conditions. When the number of times is not less than the preset number of times, the difference between the preset number of grounding resistance values ​​has not been detected to be less than the set threshold, indicating that the grounding resistance measurement device is faulty. Therefore, the measurement number verification unit 162 is required to send a seventh signal to the second alarm unit 165, so that the second alarm unit 165 issues a third alarm prompt to prompt the staff to promptly check the abnormal cause. The first alarm prompt, the second alarm prompt, and the third alarm prompt can be different, so that the staff can understand where the fault occurs according to different alarm prompts, so that the cause of the fault can be found out in time.

[0067] Optional, continue to refer to Figure 7 The tolerance checking unit 161 is connected to the display module 170 , and the measurement times checking unit 162 is further used to control the tolerance checking unit 161 to directly send the average value to the display module 170 when it is checked that the times value is not less than the preset times value.

[0068] Specifically, the tolerance inspection unit 161 is connected to the display module 170. When the number of times is not less than the preset number of times, the display module 170 still displays the average value, so that the staff can check the ground resistance value measured when the fault occurs.

[0069] Optional, Figure 8 is a schematic diagram of the structure of another ground resistance measuring device provided according to an embodiment of the present invention, referring to Figure 8 The ground resistance measuring device provided in this embodiment also includes a trigger signal output module 180; the trigger signal output module 180 is connected to the voltage signal output module 110, and the trigger signal output module 180 is used to receive a trigger instruction and send a trigger signal to the voltage signal output module 110 after receiving the trigger instruction.

[0070] Specifically, the trigger instruction may be sent by the user or automatically by the three-machine brushless excitation system. For example, when the user needs to measure the ground resistance value, the trigger instruction may be manually sent to the trigger signal output module 180. When the three-machine brushless excitation system is set to measure the ground resistance value at a specific time, the three-machine brushless excitation system will send a trigger instruction to the trigger signal output module 180 when the specific time is reached.

[0071] This embodiment provides a ground resistance measurement method, which is applied to the ground resistance measurement device provided by any embodiment of the present invention. Fig. 9is a flow chart of a ground resistance measurement method provided according to an embodiment of the present invention, referring to Fig. 9 ,

[0072] The ground resistance measurement method includes the following steps:

[0073] S110 , after receiving the trigger signal, the voltage signal output module outputs the voltage signal to the grounding resistor and sends a first signal to the voltage signal detection module and the charge and discharge detection module.

[0074] S120. The voltage signal detection module detects the change rate of the voltage signal after receiving the first signal, and sends a second signal to the ground resistance measurement module when the change rate is detected to be less than a preset change rate.

[0075] S130. After receiving the first signal, the charge and discharge detection module detects whether the distributed capacitance is completely charged or discharged, and sends a third signal to the ground resistance measurement module when it is detected that the distributed capacitance is completely charged or discharged.

[0076] S140. When the grounding resistance measuring module receives the third signal while receiving the second signal, it collects the voltage signal in the grounding resistance and outputs the grounding resistance value.

[0077] The grounding resistance measuring method provided in the embodiment of the present invention has corresponding beneficial effects as the grounding resistance measuring device provided in any embodiment of the present invention. The technical details not detailed in this embodiment are detailed in the grounding resistance measuring device provided in any embodiment of the present invention.

[0078] The grounding resistance measurement test standard is: when the ground resistance is between 0kΩ and 20kΩ, the measurement error does not exceed ±2kΩ; when the ground resistance is between 20kΩ and 500kΩ, the measurement error does not exceed ±10%; when the ground resistance is between 500kΩ and 2MΩ, the measurement error does not exceed ±15%. The following Tables 1 and 2 are data obtained by measuring the grounding resistance using the grounding resistance measuring device provided by any embodiment of the present invention. Table 1 is the data obtained by laboratory simulation, and Table 2 is the data obtained by connecting the grounding resistance measuring device to the generator and exciter. Analysis of Tables 1 and 2 shows that the grounding resistance values ​​measured by the grounding resistance measuring device provided by the embodiment of the present invention are all within the error range. It can be seen that the grounding resistance measuring device provided by this embodiment has high measurement accuracy.

[0079] Table 1

[0080]

[0081] Table 2

[0082]

[0083] It should be understood that the various forms of processes shown above can be used to reorder, add or delete steps. For example, the steps described in the present invention can be executed in parallel, sequentially or in different orders, as long as the desired results of the technical solution of the present invention can be achieved, and this document does not limit this.

[0084] The above specific implementations do not constitute a limitation on the protection scope of the present invention. It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and substitutions can be made according to design requirements and other factors. Any modification, equivalent substitution and improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A ground resistance measuring device, characterized in that: It includes a voltage signal output module, a voltage signal detection module, a charge and discharge detection module and a ground resistance measurement module; The voltage signal output module is connected to the voltage signal detection module and the charge and discharge detection module, and the voltage signal output module is used to output a voltage signal to the grounding resistor after receiving a trigger signal and send a first signal to the voltage signal detection module and the charge and discharge detection module; The voltage signal detection module is connected to the ground resistance measurement module, and the voltage signal detection module is used to detect the change rate of the voltage signal after receiving the first signal, and send a second signal to the ground resistance measurement module when it is detected that the change rate is less than a preset change rate; The charge and discharge detection module is connected to the ground resistance measurement module, and the charge and discharge detection module is used to detect whether the distributed capacitance is charged or discharged after receiving the first signal, and send a third signal to the ground resistance measurement module when it is detected that the distributed capacitance is charged or discharged; The ground resistance measurement module is connected to the voltage signal output module, and the ground resistance measurement module is used to collect the voltage signal in the ground resistance and output the ground resistance value when receiving the third signal at the same time as receiving the second signal; It also includes a ground resistance value inspection module and a display module; The grounding resistance value inspection module is connected to the grounding resistance measurement module and the display module, and the grounding resistance value inspection module is used to obtain a preset number of grounding resistance values ​​from the grounding resistance measurement module and inspect whether the preset number of grounding resistance values ​​meet the set conditions, and when the preset number of grounding resistance values ​​meet the set conditions, output the average value of the preset number of grounding resistance values ​​to the display module, wherein the preset number is a positive integer greater than 1; The display module is used to display the average value; The ground resistance value inspection module includes a tolerance inspection unit, a measurement number inspection unit and a pre-value inspection unit; The tolerance inspection unit is connected to the ground resistance measurement module, the measurement number inspection unit and the pre-value inspection unit, and the tolerance inspection unit is used to obtain the preset number of ground resistance values ​​from the ground resistance measurement module and output the average value of the preset number of ground resistance values ​​to the pre-value inspection unit when it is checked that the difference between the preset number of ground resistance values ​​is less than the set threshold value, and is also used to send a fifth signal to the measurement number inspection unit when it is checked that the difference between the preset number of ground resistance values ​​is not less than the set threshold value; The pre-value checking unit is used for outputting the average value to the display module when checking that the average value is greater than the preset ground resistance value; The measurement number verification unit is connected to the voltage signal output module, and is used to verify the number of times the voltage signal output module receives the trigger signal when receiving the fifth signal, and send a trigger signal to the voltage signal output module when it is verified that the number is less than a preset number.

2. The ground resistance measuring device according to claim 1, characterized in that: The voltage signal detection module includes a preset change rate input unit and a voltage signal detection unit; The preset change rate input unit is connected to the voltage signal detection unit, and the preset change rate input unit is used to receive the preset change rate input by the user and send the preset change rate to the voltage signal detection unit; The voltage signal detection unit is connected to the voltage signal output module and the ground resistance measurement module. The voltage signal detection unit is used to detect the change rate of the voltage signal after receiving the first signal, and send the second signal to the ground resistance measurement module when it is detected that the change rate is less than the preset change rate.

3. The ground resistance measuring device according to claim 1, characterized in that: The charge and discharge detection module includes a time input unit and a timing control unit; The time input unit is connected to the timing control unit, and the time input unit is used to receive a preset time value input by a user and send the preset time value to the timing control unit; The timing control unit is connected to the voltage signal output module and the ground resistance measurement module. The timing control unit is used to start timing when the distributed capacitance starts to charge or discharge after receiving the first signal, and send the third signal to the ground resistance measurement module until the timing duration is equal to the preset time value.

4. The ground resistance measuring device according to claim 1, characterized in that: Also includes an alarm module; The alarm module is connected to the ground resistance measurement module, and the ground resistance measurement module is also used to send a fourth signal to the alarm module when the second signal is not received while the third signal is received. The alarm module is used to issue a first alarm prompt when the fourth signal is received.

5. The ground resistance measuring device according to claim 1, characterized in that: The ground resistance value inspection module also includes a first alarm unit and a second alarm unit; The first alarm unit is connected to the pre-value checking unit, and the pre-value checking unit is further used to send a sixth signal to the first alarm unit when it is checked that the average value is not greater than the preset grounding resistance value, and the first alarm unit is used to issue a second alarm prompt when receiving the sixth signal; The second alarm unit is connected to the measurement number verification unit, and the measurement number verification unit is also used to send a seventh signal to the second alarm unit when it is verified that the number value is not less than the preset number value, and the second alarm unit issues a third alarm prompt when receiving the seventh signal.

6. The ground resistance measuring device according to claim 1, characterized in that: The tolerance checking unit is connected to the display module, and the measurement times checking unit is further used for controlling the tolerance checking unit to directly send the average value to the display module when it is checked that the times value is not less than the preset times value.

7. The ground resistance measuring device according to claim 1, characterized in that: Also includes a trigger signal output module; The trigger signal output module is connected to the voltage signal output module, and the trigger signal output module is used to receive a trigger instruction and send a trigger signal to the voltage signal output module after receiving the trigger instruction.

8. A method for measuring ground resistance, characterized in that: The voltage signal output module is connected to the voltage signal detection module and the charge and discharge detection module; the voltage signal detection module is connected to the ground resistance measurement module; the charge and discharge detection module is connected to the ground resistance measurement module; The ground resistance measurement module is connected to the voltage signal output module; The ground resistance measurement method comprises: The voltage signal output module outputs a voltage signal to the grounding resistor after receiving the trigger signal and sends a first signal to the voltage signal detection module and the charge and discharge detection module; The voltage signal detection module detects the change rate of the voltage signal after receiving the first signal, and sends a second signal to the ground resistance measurement module when detecting that the change rate is less than a preset change rate; The charge and discharge detection module detects whether the distributed capacitance is fully charged or fully discharged after receiving the first signal, and sends a third signal to the ground resistance measurement module when it is detected that the distributed capacitance is fully charged or fully discharged; When the ground resistance measuring module receives the third signal while receiving the second signal, it collects the voltage signal in the ground resistance and outputs the ground resistance value; It also includes a ground resistance value inspection module and a display module; The grounding resistance value inspection module is connected to the grounding resistance measurement module and the display module, and the grounding resistance value inspection module is used to obtain a preset number of grounding resistance values ​​from the grounding resistance measurement module and inspect whether the preset number of grounding resistance values ​​meet the set conditions, and when the preset number of grounding resistance values ​​meet the set conditions, output the average value of the preset number of grounding resistance values ​​to the display module, wherein the preset number is a positive integer greater than 1; The display module is used to display the average value; The ground resistance value inspection module includes a tolerance inspection unit, a measurement number inspection unit and a pre-value inspection unit; The tolerance inspection unit is connected to the ground resistance measurement module, the measurement number inspection unit and the pre-value inspection unit, and the tolerance inspection unit is used to obtain the preset number of ground resistance values ​​from the ground resistance measurement module and output the average value of the preset number of ground resistance values ​​to the pre-value inspection unit when it is checked that the difference between the preset number of ground resistance values ​​is less than the set threshold value, and is also used to send a fifth signal to the measurement number inspection unit when it is checked that the difference between the preset number of ground resistance values ​​is not less than the set threshold value; The pre-value checking unit is used for outputting the average value to the display module when checking that the average value is greater than the preset ground resistance value; The measurement number verification unit is connected to the voltage signal output module, and is used to verify the number of times the voltage signal output module receives the trigger signal when receiving the fifth signal, and send a trigger signal to the voltage signal output module when it is verified that the number is less than a preset number.

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