Insulation detection and abnormal position judgment method suitable for energy storage converter

Abstract

The invention provides an insulation detection and abnormal position judgment method suitable for an energy storage converter, and the method comprises the following steps: 1, completing the auxiliary power supply of an internal control system after an AC / DC molded case circuit breaker of the energy storage converter is closed; 2, detecting the working state of the current energy storage converter, and if the current energy storage converter is in a non-shutdown state or the battery voltage detection value is not greater than a set threshold value, not carrying out insulation detection related operation; if the battery is in the shutdown state at present and the voltage value of the battery is greater than a set threshold value, entering the next step, and calculating an insulation resistance value; according to the invention, the optimized insulation impedance detection circuit is matched with a multi-software filtering method to detect whether insulation abnormity exists, and whether an abnormal point is located in the converter is judged according to the direct current difference between the positive electrode inlet and the negative electrode outlet of the direct current side.

Description

Technical Field

[0001] The present invention relates to the technical field of insulation detection, and in particular to an insulation detection and abnormal position judgment method suitable for an energy storage converter. Background Art

[0002] To solve the problem in existing detection methods that the insulation impedance value detection fluctuates greatly and is inaccurate, and it is impossible to determine whether the insulation impedance abnormal point is located inside the energy storage inverter or in the external battery system. Summary of the invention

[0003] In order to make up for the deficiencies of the prior art, the embodiments of the present application propose an insulation detection and abnormal position judgment method suitable for an energy storage converter to solve the problems existing in the prior art.

[0004] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0005] A method for insulation detection and abnormal position determination of an energy storage converter, comprising the following steps:

[0006] Step 1: After the AC and DC molded case circuit breakers of the energy storage converter are closed, the auxiliary power supply of the internal control system is completed;

[0007] Step 2: Detect the current working state of the energy storage converter. If it is currently in a non-shutdown state or the battery voltage detection value is not greater than the set threshold, no insulation detection related operations are performed; if it is currently in a shutdown state and the battery voltage value is greater than the set threshold, proceed to the next step to calculate the insulation impedance value;

[0008] Step 3, enter the insulation impedance value calculation module, calculate the insulation impedance value of the positive electrode of the battery to PE and the insulation impedance value of the negative electrode of the battery to PE;

[0009] Step 4: Determine the smaller value of the insulation impedance between the positive and negative electrodes and the PE and the impedance threshold. If the smaller impedance value is not less than the impedance threshold, the insulation is normal and the test returns to step 2 for the next test; if the smaller impedance value is less than the impedance threshold, the test proceeds to the next step.

[0010] Step 5: If the insulation alarm processing method set by the system is shutdown upon failure, the energy storage converter will directly shut down and enter the fault state. In this way, the abnormal point location will no longer be determined. If the insulation alarm processing method set by the system is only alarm without shutdown, proceed to the next step.

[0011] Step 6: Check whether the system is in a charging or discharging state. If not, continue to wait for power instructions in the current state; if so, proceed to the next step;

[0012] Step 7, enter the DC positive and negative current processing module, obtain the positive and negative current values ​​Idc_Filter_P and Idc_Filter_N after filtering, and calculate the difference delta_Idc between the two;

[0013] Step 8: If delta_Idc is greater than the DC threshold, it is determined that the abnormal point of the insulation impedance is located inside the energy storage converter; otherwise, it is determined that the abnormal point of the insulation impedance is located outside the energy storage converter.

[0014] As a further technical solution of the present invention: the insulation impedance value calculation module is implemented by an insulation impedance value detection circuit, which includes a resistor R1, a resistor R2, a resistor R3, a resistor R4, a relay contact switch K1 and a relay contact switch K2, one end of the resistor R1 is connected to the resistor R2 and the relay contact switch K1, the other end of the resistor R2 is connected to the battery positive electrode BAT+, the other end of the resistor R1 is connected to the relay K1 and the resistor R3, the other end of the resistor R3 is connected to the PE sampling circuit and the resistor R6, one end of the resistor R4 is connected to the resistor R5 and the relay contact switch K2, the other end of the resistor R5 is connected to the battery positive electrode BAT-, and the other end of the resistor R4 is connected to the relay K2 and the other end of the resistor R6.

[0015] As a further technical solution of the present invention: the resistance value of the resistor R1 is the same as that of the resistor R4, the resistance value of the resistor R2 is the same as that of the resistor R5, and the resistance value of the resistor R3 is the same as that of the resistor R6.

[0016] As a further technical solution of the present invention: inside the energy storage inverter, at the outer end of the DC load switch, a Hall current sensor is installed on the positive and negative incoming lines of the battery, respectively, to detect the DC current signal flowing through the positive electrode of the energy storage inverter and the DC current signal flowing through the negative electrode of the energy storage inverter, respectively.

[0017] As a further technical solution of the present invention: the calculation method of insulation resistance is as follows:

[0018] Step 3.1: In the shutdown state, if the battery voltage sampling value is greater than the set threshold, the second step of detection will be entered. Otherwise, the next step will not be performed and the insulation resistance value detection will be stopped;

[0019] Step 3.2, disconnect the relay switches K1 and K2, and then continuously collect the voltage value of the positive electrode of the battery to PE three times, the values ​​are Up1_t1, Up1_t2, Up1_t3 respectively; continuously collect the voltage value of the negative electrode of the battery to PE three times, the values ​​are Un1_t1, Un1_t2, Un1_t3 respectively, and calculate the values ​​Up1_m1 and Un1_m1 in the middle of the two groups of data values ​​respectively;

[0020] Step 3.3 and step 2 are repeated k times to obtain k intermediate values, namely Up1_m1, Up1_m2, ..., Up1_mk and Un1_m1, Un1_m2, ..., Un1_mk, and the average value of each group is calculated. and

[0021] Step 3.4, close the relay switches K1 and K2, and then continuously collect the voltage value of the positive electrode of the battery to PE three times, the values ​​are Up2_t1, Up2_t2, Up2_t3 respectively; continuously collect the voltage value of the negative electrode of the battery to PE three times, the values ​​are Un2_t1, Un2_t2, Un2_t3 respectively, and calculate the values ​​Up2_m1 and Un2_m1 in the middle of the two groups of data values ​​respectively;

[0022] Repeat steps 3.5 and 4 k times to obtain k intermediate values, namely Up2_m1, Up2_m2, ..., Up2_mk and Un2_m1, Un2_m2, ..., Un2_mk, and calculate the average value of each group. and

[0023] Step 3.6, calculate the intermediate variables R123 = R1 + R2 + R3 = R4 + R5 + R6, R23 = R2 + R3 = R5 + R6;

[0024] Step 3.7: According to the formula Calculate the total equivalent impedance value of the battery positive electrode to PE;

[0025] Step 3.8: According to the formula Calculate the total equivalent impedance value of the battery negative electrode to PE;

[0026] Step 3.9: According to the formula Calculate the insulation resistance value of the battery positive electrode to PE;

[0027] Step 3.10: According to the formula Calculate the insulation resistance value of the battery negative electrode to PE.

[0028] As a further technical solution of the present invention: the DC positive and negative current processing module includes a data filter, the input signal of the data filter is the positive current original value Idc_S_P and the negative current original value Idc_S_N, and the output signal is the processed positive current signal filtered value Idc_Filter_P and the negative current filtered value Idc_Filter_N.

[0029] As a further technical solution of the present invention: the current value processing flow steps are as follows:

[0030] Ⅰ. The sampled positive current original values ​​Idc_S_P and Idc_S_N are respectively passed through digital low-pass filters to obtain filtered current values ​​Idc_DF_P and Idc_DF_N;

[0031] Ⅱ. Obtain the current values ​​after filtering in step 1 three times in a row. The positive poles are Idc_DF_P1, Idc_DF_P2, and Idc_DF_P3 respectively; the negative poles are Idc_DF_N1, Idc_DF_N2, and Idc_DF_N3 respectively; calculate the values ​​Idc_P_M1 and Idc_N_M1 in the middle of the two groups of data values ​​respectively;

[0032] III. Repeat step II k times to obtain k intermediate values, namely Idc_P_M1, Idc_P_M2, ..., Idc_P_Mk and Idc_N_M1, Idc_N_M2, ..., Idc_N_Mk, and calculate the final filtering result of the DC side current. and

[0033] One or more technical solutions provided in the embodiments of the present application have at least the following technical effects or advantages:

[0034] The present invention detects whether there is insulation abnormality through an optimized insulation impedance detection circuit in combination with a multiple software filtering method, and determines whether the abnormal point is located inside the converter based on the DC current difference between the positive pole inlet and the negative pole outlet on the DC side. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 This is a schematic diagram of the insulation impedance value detection circuit;

[0036] Figure 2 It is a schematic diagram of a method for processing DC side current data;

[0037] Figure 3 The figure is a general flow chart of the insulation detection and abnormal position judgment method. DETAILED DESCRIPTION

[0038] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0039] The present invention proposes an insulation detection and abnormal position judgment method applicable to an energy storage converter, comprising the following steps:

[0040] Step 1: After the AC and DC molded case circuit breakers of the energy storage converter are closed, the auxiliary power supply of the internal control system is completed;

[0041] Step 2: Detect the current working state of the energy storage converter. If it is currently in a non-shutdown state or the battery voltage detection value is not greater than the set threshold, no insulation detection related operations are performed; if it is currently in a shutdown state and the battery voltage value is greater than the set threshold, proceed to the next step to calculate the insulation impedance value;

[0042] Step 3, enter the insulation impedance value calculation module, calculate the insulation impedance value of the positive electrode of the battery to PE and the insulation impedance value of the negative electrode of the battery to PE;

[0043] Step 4: Determine the smaller value of the insulation impedance between the positive and negative electrodes and the PE and the impedance threshold. If the smaller impedance value is not less than the impedance threshold, the insulation is normal and the test returns to step 2 for the next test; if the smaller impedance value is less than the impedance threshold, the test proceeds to the next step.

[0044] Step 5: If the insulation alarm processing method set by the system is shutdown upon failure, the energy storage converter will directly shut down and enter the fault state. In this way, the abnormal point location will no longer be determined. If the insulation alarm processing method set by the system is only alarm without shutdown, proceed to the next step.

[0045] Step 6: Check whether the system is in a charging or discharging state. If not, continue to wait for power instructions in the current state; if so, proceed to the next step;

[0046] Step 7, enter the DC positive and negative current processing module, obtain the positive and negative current values ​​Idc_Filter_P and Idc_Filter_N after filtering, and calculate the difference delta_Idc between the two;

[0047] Step 8: If delta_Idc is greater than the DC threshold, it is determined that the abnormal point of the insulation impedance is located inside the energy storage converter; otherwise, it is determined that the abnormal point of the insulation impedance is located outside the energy storage converter.

[0048] Figure 1The schematic diagram of the insulation impedance detection circuit designed in this method. In the figure, BAT+ and BAT- respectively indicate the positive and negative electrodes of the battery; in the figure, R1, R2, R3, R4, R5, and R6 are all resistors, where the resistance values ​​are R1=R4, R2=R5, and R3=R6; Rp and Rn are the total equivalent resistances of the positive and negative electrodes of the battery to the earth PE, respectively, where Rp is composed of the impedance value R_AD_P of the sampling circuit of the battery positive electrode to PE and the insulation impedance value Rpx of the battery positive electrode to PE, and Rn is composed of the impedance value R_AD_N of the sampling circuit of the battery negative electrode to PE and the insulation impedance value Rnx of the battery negative electrode to PE; Up and Un respectively indicate the sampling voltage values ​​of the positive and negative electrodes of the battery to PE; K1 and K2 indicate controllable relay contact switches.

[0049] The calculation method of insulation resistance is as follows:

[0050] Step 3.1: In the shutdown state, if the battery voltage sampling value is greater than the set threshold, the second detection step will be entered. Otherwise, the next step will not be performed and the insulation resistance value detection will be stopped;

[0051] Step 3.2, disconnect the relay switches K1 and K2, and then continuously collect the voltage value of the positive electrode of the battery to PE three times, the values ​​are Up1_t1, Up1_t2, Up1_t3 respectively; continuously collect the voltage value of the negative electrode of the battery to PE three times, the values ​​are Un1_t1, Un1_t2, Un1_t3 respectively, and calculate the values ​​Up1_m1 and Un1_m1 in the middle of the two groups of data values ​​respectively;

[0052] Step 3.3 and step 2 are repeated k times to obtain k intermediate values, namely Up1_m1, Up1_m2, ..., Up1_mk and Un1_m1, Un1_m2, ..., Un1_mk, and the average value of each group is calculated. and

[0053] Step 3.4, close the relay switches K1 and K2, and then continuously collect the voltage value of the positive electrode of the battery to PE three times, the values ​​are Up2_t1, Up2_t2, Up2_t3 respectively; continuously collect the voltage value of the negative electrode of the battery to PE three times, the values ​​are Un2_t1, Un2_t2, Un2_t3 respectively, and calculate the values ​​Up2_m1 and Un2_m1 in the middle of the two groups of data values ​​respectively;

[0054] Repeat steps 3.5 and 4 k times to obtain k intermediate values, namely Up2_m1, Up2_m2, ..., Up2_mk and Un2_m1, Un2_m2, ..., Un2_mk, and calculate the average value of each group. and

[0055] Step 3.6, calculate the intermediate variables R123 = R1 + R2 + R3 = R4 + R5 + R6, R23 = R2 + R3 = R5 + R6;

[0056] Step 3.7: According to the formula Calculate the total equivalent impedance value of the battery positive electrode to PE;

[0057] Step 3.8: According to the formula Calculate the total equivalent impedance value of the battery negative electrode to PE;

[0058] Step 3.9: According to the formula Calculate the insulation resistance value of the battery positive electrode to PE;

[0059] Step 3.10: According to the formula Calculate the insulation resistance value of the battery negative electrode to PE.

[0060] Inside the energy storage converter, at the outer end of the DC load switch, a Hall current sensor is installed on the positive and negative incoming lines of the battery, respectively, to detect the DC current signal flowing through the positive electrode of the energy storage converter and the DC current signal flowing through the negative electrode of the energy storage converter. Figure 2 Schematic diagram of the DC side current data processing method. In the figure, Idc_S_P and Idc_S_N are respectively the positive current original value and the negative current original value; Idc_Filter_P and Idc_Filter_N are respectively the positive current filter value and the negative current filter value after the final data processing.

[0061] The current value processing steps are as follows:

[0062] Ⅰ. The sampled positive current original values ​​Idc_S_P and Idc_S_N are respectively passed through digital low-pass filters to obtain filtered current values ​​Idc_DF_P and Idc_DF_N;

[0063] Ⅱ. Obtain the current values ​​after filtering in step 1 three times in a row. The positive poles are Idc_DF_P1, Idc_DF_P2, and Idc_DF_P3 respectively; the negative poles are Idc_DF_N1, Idc_DF_N2, and Idc_DF_N3 respectively; calculate the values ​​Idc_P_M1 and Idc_N_M1 in the middle of the two groups of data values ​​respectively;

[0064] III. Repeat step II k times to obtain k intermediate values, namely Idc_P_M1, Idc_P_M2, ..., Idc_P_Mk and Idc_N_M1, Idc_N_M2, ..., Idc_N_Mk, and calculate the final filtering result of the DC side current. and

[0065] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the present invention can be implemented in other specific forms without departing from the spirit or essential features of the present invention. Therefore, the embodiments should be considered exemplary and non-restrictive in all respects, and the scope of the present invention is defined by the appended claims rather than the above description, and it is intended that all changes falling within the meaning and scope of the equivalent elements of the claims be included in the present invention.

[0066] In addition, it should be understood that although this specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This narrative method of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment have also been appropriately combined to form other implementation modes that are easy for those skilled in the art to understand.

Claims

1. A method for insulation detection and abnormal position determination of an energy storage converter, characterized in that: The following steps are involved: Step 1: After the AC and DC molded case circuit breakers of the energy storage converter are closed, the auxiliary power supply of the internal control system is completed; Step 2: Detect the current working state of the energy storage converter. If it is currently in a non-shutdown state or the battery voltage detection value is not greater than the set threshold, no insulation detection related operations are performed; if it is currently in a shutdown state and the battery voltage value is greater than the set threshold, proceed to the next step to calculate the insulation impedance value; Step 3, enter the insulation impedance value calculation module, calculate the insulation impedance value of the positive electrode of the battery to PE and the insulation impedance value of the negative electrode of the battery to PE; Step 4, determine the smaller value of the insulation impedance between the positive and negative electrodes to PE and the impedance threshold; if the smaller impedance value of the two is not less than the impedance threshold, then the insulation is normal, and directly return to step 2 for the next test; if the smaller impedance value of the two is less than the impedance threshold, proceed to the next step; Step 5: If the insulation alarm processing method set by the system is shutdown upon failure, the energy storage converter will directly shut down and enter the fault state. In this way, the abnormal point location will no longer be determined. If the insulation alarm processing method set by the system is only alarm without shutdown, proceed to the next step. Step 6: Check whether the system is in a charging or discharging state. If not, continue to wait for power instructions in the current state; if so, proceed to the next step; Step 7, enter the DC positive and negative current processing module, obtain the positive and negative current values ​​Idc_Filter_P and Idc_Filter_N after filtering, and calculate the difference delta_Idc between the two; Step 8: If delta_Idc is greater than the DC threshold, it is determined that the abnormal point of the insulation impedance is located inside the energy storage converter; otherwise, it is determined that the abnormal point of the insulation impedance is located outside the energy storage converter.

2. The insulation detection and abnormal position determination method for energy storage converter according to claim 1, characterized in that: The insulation impedance value calculation module is implemented by an insulation impedance value detection circuit, which includes a resistor R1, a resistor R2, a resistor R3, a resistor R4, a relay contact switch K1 and a relay contact switch K2, one end of the resistor R1 is connected to the resistor R2 and the relay contact switch K1, the other end of the resistor R2 is connected to the battery positive electrode BAT+, the other end of the resistor R1 is connected to the relay K1 and the resistor R3, the other end of the resistor R3 is connected to the PE sampling circuit and the resistor R6, one end of the resistor R4 is connected to the resistor R5 and the relay contact switch K2, the other end of the resistor R5 is connected to the battery positive electrode BAT-, and the other end of the resistor R4 is connected to the relay K2 and the other end of the resistor R6.

3. The insulation detection and abnormal position determination method for energy storage converter according to claim 2, characterized in that: The resistance value of the resistor R1 is the same as that of the resistor R4 , the resistance value of the resistor R2 is the same as that of the resistor R5 , and the resistance value of the resistor R3 is the same as that of the resistor R6 .

4. The insulation detection and abnormal position determination method for energy storage converter according to claim 2, characterized in that: Inside the energy storage converter, at the outer end of the DC load switch, a Hall current sensor is installed on the positive and negative incoming lines of the battery, respectively, to detect the DC current signal flowing through the positive electrode of the energy storage converter and the DC current signal flowing through the negative electrode of the energy storage converter.

5. The insulation detection and abnormal position determination method for energy storage converter according to claim 3, characterized in that: The calculation method of insulation resistance is as follows: Step 3.1: In the shutdown state, if the battery voltage sampling value is greater than the set threshold, the second detection step is entered; otherwise, the next step is not performed and the insulation resistance value detection is stopped; Step 3.2, disconnect the relay switches K1 and K2, and then continuously collect the voltage value of the positive electrode of the battery to PE three times, the values ​​are Up1_t1, Up1_t2, Up1_t3 respectively; continuously collect the voltage value of the negative electrode of the battery to PE three times, the values ​​are Un1_t1, Un1_t2, Un1_t3 respectively, and calculate the values ​​Up1_m1 and Un1_m1 in the middle of the two groups of data values ​​respectively; Step 3.3 and step 2 are repeated k times to obtain k intermediate values, namely Up1_m1, Up1_m2, ..., Up1_mk and Un1_m1, Un1_m2, ..., Un1_mk, and the average value of each group is calculated. and Step 3.4, close the relay switches K1 and K2, and then continuously collect the voltage value of the positive electrode of the battery to PE three times, the values ​​are Up2_t1, Up2_t2, Up2_t3 respectively; continuously collect the voltage value of the negative electrode of the battery to PE three times, the values ​​are Un2_t1, Un2_t2, Un2_t3 respectively, and calculate the values ​​Up2_m1 and Un2_m1 in the middle of the two groups of data values ​​respectively; Repeat steps 3.5 and 4 k times to obtain k intermediate values, namely Up2_m1, Up2_m2, ..., Up2_mk and Un2_m1, Un2_m2, ..., Un2_mk, and calculate the average value of each group. and Step 3.6, calculate the intermediate variables R123 = R1 + R2 + R3 = R4 + R5 + R6, R23 = R2 + R3 = R5 + R6; Step 3.7: According to the formula Calculate the total equivalent impedance value of the battery positive electrode to PE; Step 3.8: According to the formula Calculate the total equivalent impedance value of the battery negative electrode to PE; Step 3.9: According to the formula Calculate the insulation resistance value of the battery positive electrode to PE; Step 3.10: According to the formula Calculate the insulation resistance value of the battery negative electrode to PE.

6. The insulation detection and abnormal position determination method for energy storage converter according to claim 1, characterized in that: The DC positive and negative current processing module includes a data filter, the input signal of the data filter is the positive current original value Idc_S_P and the negative current original value Idc_S_N, and the output signal is the processed positive current signal filtered value Idc_Filter_P and the negative current filtered value Idc_Filter_N.

7. The insulation detection and abnormal position determination method for energy storage converter according to claim 6, characterized in that: The current value processing steps are as follows: Ⅰ. The sampled positive current original values ​​Idc_S_P and Idc_S_N are respectively passed through digital low-pass filters to obtain filtered current values ​​Idc_DF_P and Idc_DF_N; Ⅱ. Obtain the current values ​​after filtering in step 1 three times in a row. The positive poles are Idc_DF_P1, Idc_DF_P2, and Idc_DF_P3 respectively; the negative poles are Idc_DF_N1, Idc_DF_N2, and Idc_DF_N3 respectively; calculate the values ​​Idc_P_M1 and Idc_N_M1 in the middle of the two groups of data values ​​respectively; III. Repeat step II k times to obtain k intermediate values, namely Idc_P_M1, Idc_P_M2, ..., Idc_P_Mk and Idc_N_M1, Idc_N_M2, ..., Idc_N_Mk, and calculate the final filtering result of the DC side current. and

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