CN110579647B - Control protection system with insulation monitoring and active prevention functions - Google Patents
Control protection system with insulation monitoring and active prevention functions Download PDFInfo
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- CN110579647B CN110579647B CN201910682138.7A CN201910682138A CN110579647B CN 110579647 B CN110579647 B CN 110579647B CN 201910682138 A CN201910682138 A CN 201910682138A CN 110579647 B CN110579647 B CN 110579647B
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- G01R31/081—Locating faults in cables, transmission lines, or networks according to type of conductors
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Abstract
The invention discloses a control protection system with insulation monitoring and active precaution functions, which comprises a DC/DC power supply module, an open-in element linear optocoupler sampling module and an insulation monitoring device, wherein the open-in element linear optocoupler sampling module is connected with the DC/DC power supply module; the output end of the DC/DC power supply module is connected with a power supply interface of the input port of the switching-in element; the linear optocoupler sampling module of the open-in element is used for monitoring the voltage of the input port of the open-in element, judging whether the open-in element is open or not and monitoring the voltage U of the open-in elementOpening n(ii) a The insulation monitoring device is connected to a line connected with the output end of the DC/DC power supply module and a power supply interface of the input port of the switching-in element and used for detecting and judging whether the positive electrode and the negative electrode of the bus normally operate or not, starting a branch line selection function when the negative electrode and the positive electrode are grounded and the negative electrode and the positive electrode are grounded simultaneously, and checking the voltage at two ends of each switching-in element. And by adopting the DC/DC power supply module, the abnormal mutual interference between the protection device and the DC system is avoided, and the ground capacitance of the DC system is reduced.
Description
Technical Field
The invention relates to the field of power monitoring, in particular to a control protection system with insulation monitoring and active prevention functions.
Background
The existing external cable insulation reduction has the following detection technology: the insulation monitoring device is added in the direct current system, but the insulation monitoring device can only monitor which branch is grounded (a power supply loop is shared by one set of protection device or a plurality of sets of protection devices), but which specific cable core is grounded, and the direct current grounding finder is required to be utilized to measure each branch of the direct current system by utilizing the clamp meter until a fault point is found, so that the work risk of direct current grounding finding is large, and the work is complicated.
The sensitivity of the existing insulation monitoring device can not meet the requirement of microcomputer protection because the open-in internal resistance of the microcomputer protection is larger than 100k omega, but the sensitivity of the insulation monitoring device is only 15k omega (110V system), 25k omega (220V system), and the sensitivity of the portable direct current grounding finder is only 100k omega. Therefore, it is an urgent matter to develop an insulation monitoring device that avoids the influence of the microcomputer protection internal resistance.
The existing insulation monitoring device can only monitor the interference alternating current which directly enters from a direct current bus, and when the interference alternating current enters from an opening element protected by a microcomputer, such as an optical coupler, a relay and the like, the existing insulation monitoring device cannot find out the interference of the type due to insufficient sensitivity. This type of interference, in turn, severely affects the reliability of the protection.
The secondary circuit of the existing protection device and the direct current system is extremely complex and mutually influenced. The grounding of the external loop cable of each set of secondary equipment (including protection, automation and other equipment) can affect the insulation condition of the whole system, so that the insulation monitoring system and the direct current system are abnormally complex. And measures for preventing protection against malfunction: the direct current system is grounded through a high-resistance balance resistor, and is expected to protect against misoperation when one point of grounding normally occurs. However, as the direct current system is increasingly complex, the capacitance to ground of the direct current system is increased, the open internal resistance of microcomputer protection is larger than 100k omega, and when one point is grounded, protection misoperation is frequently caused.
The external port of the existing protection, automation device is shown in fig. 1, and therefore when the external cable that opens into the input port of the component is grounded, it will cause the dc system to be grounded. (grounding of the external cable of the break-in element will result in grounding of the external cable of the input port of the break-in element of another protective, automated device, so that the external cable grounding analysis is the same for both the break-in element and the break-out element).
Opening the element: for the acquisition of the switching value, in order to improve the anti-interference performance of the equipment, the following requirements are generally provided: 1. generally, the external circuit and the microcomputer control and protection equipment are required to be isolated. 2. Because the direct current system is a high-resistance balanced grounding system, the voltage of a bus of the direct current system to the ground is 50% UN during normal operation, and if the direct current system is grounded at one point, the voltage at two ends of the switching-in element is equal to the voltage of the negative electrode of the bus of the direct current system to the ground at the grounding moment, so that the switching-in element can be mistakenly operated when the actuation voltage of the switching-in element is lower than 50% Un. In order to prevent the malfunction, the operating voltage is generally required to be greater than 55% UN and less than 70% UN. The circuit involving a dc trip is even required to have an operating power of more than 5W.
Existing opening elements include: 1. a relay; 2. voltage-stabilizing tube: in order to achieve an operating voltage of more than 55% UN and less than 70% Un, a voltage regulator tube is generally adopted for early microcomputer protection. However, the open-type light-coupled device manufactured by the voltage-stabilizing tube has small internal resistance, large power and serious heat generation. The principle of opening the stabilivolt is shown in figure 2. 3. Triode: most of the manufacturers adopt a triode to replace a voltage stabilizing tube. However, the transistor is complicated in design and improperly matched, which may cause the open-in element to fail, and the open-in circuit diagram of the transistor is shown in fig. 3.
Because the relay, the voltage-regulator tube and the triode are all nonlinear elements, the current transmission characteristic curve of the nonlinear optocoupler is nonlinear, and the optocoupler is suitable for transmission of switching signals and is not suitable for transmission of analog quantity. The commonly used 4N series optical coupler belongs to the nonlinear optical coupler
Disclosure of Invention
The present invention is directed to overcome the above-mentioned deficiencies in the prior art and to provide a control and protection system with insulation monitoring and active guarding functions.
In order to achieve the purpose, the technical scheme of the invention is as follows:
a control protection system with insulation monitoring and active precaution functions comprises a DC/DC power supply module, an open-in element linear optocoupler sampling module and an insulation monitoring device;
the output end of the DC/DC power supply module is connected with a power supply interface of the input port of the switching-in element;
the linear optocoupler sampling module of the open-in element is used for monitoring the voltage of the input port of the open-in element, judging whether the open-in element is open or not and monitoring the voltage U of the open-in elementOpening nN is a positive integer;
the insulation monitoring device is connected to a circuit connected with the output end of the DC/DC power supply module and a power supply interface of the input port of the switching-in element and used for detecting and judging whether the positive electrode and the negative electrode of the bus run normally or not, when the negative electrode and the positive electrode are judged to be grounded, a bus ground resistance detection process is started, a bus ground resistance is calculated, then a branch line selection function is started, and a ground resistance calculation process is carried out after a fault branch is selected.
Furthermore, the insulation monitoring device comprises two bus voltage monitoring modules and a detection bridge resistance module; one end of a bus voltage monitoring module is connected to the positive bus, and the other end of the bus voltage monitoring module is grounded; one end of the other bus voltage monitoring module is connected to the negative bus, and the other end of the other bus voltage monitoring module is grounded; one end of the detection bridge resistance module is connected to the negative bus, and the other end of the detection bridge resistance module is grounded through the disconnecting link switch.
Furthermore, the bus voltage monitoring module and the open-in element linear optical coupling sampling module have the same or similar structures and respectively comprise a linear resistance voltage division unit, a capacitance filtering unit, a linear optical coupling sampling unit and a digital-to-analog conversion unit which are sequentially connected; the linear resistance voltage dividing unit is used for adjusting current flowing through the linear optocoupler to a linear area of the linear optocoupler, the capacitance filtering unit is used for preventing abnormal interference from entering the linear optocoupler sampling unit, the linear optocoupler sampling unit is used for collecting current flowing through the linear optocoupler and converting the current into analog quantity adaptive to the digital-to-analog sampling unit, the digital-to-analog conversion unit is used for converting the analog quantity converted by the linear optocoupler into digital quantity, judging whether alternating current channeling exists according to the converted digital quantity and calculating channeling interference voltage of the digital-to-analog conversion unit.
Further, the insulation monitoring device detects whether the positive and negative poles of the bus normally operate in the following manner:
the resistance of the linear resistance voltage division unit is R1, the resistance of the detection bridge resistance module is R2, and when the detection bridge resistance module operates normally, the disconnecting link is disconnected;
when in normal operation, the bus voltage of the bus anode is Um is just,
When in normal operation, the bus voltage of the bus cathode is Um is minus，
When the device is in normal operation, the voltage at the two ends of the switch-in measured by the switch-in measuring module is UOpening n,
Normal operation, no abnormal insulation, Um is just＝Um is minus；
When U is turnedm is just>Um is minusIf the difference exceeds the first set value, the cathode is judged to be grounded;
when U is turnedm is minus>Um is justAnd if the difference exceeds a second set value, the anode is judged to be grounded.
Further, the insulation monitoring device starts the bus line to ground resistance detection process in the following manner: firstly, recording the bus voltage before and after the knife switch is switched on, and calculating the bus ground resistance according to the change of the bus voltage;
the resistance to ground of the positive electrode of the bus is Rm+The resistance to ground of the negative electrode of the bus is Rm-；
Before the knife switch is switched on, the bus voltage of the bus anode is Um is 1The bus voltage of the bus cathode is Um minus 1，
After the knife switch is switched on, the bus voltage of the bus anode is Um is 2The bus voltage of the bus cathode is Um minus 2，
Then
Further, the mode that the insulation monitoring device starts the branch line selection function is as follows:
when U is turnedOpening n＝Um is minusWhen the cable core branch is grounded in a metallic mode, the cable core branch is considered to be grounded in a metallic mode;
when U is turnedOpening n<Um is minusAnd when the interference value is larger than the set interference value, the cable core branch is considered to have resistance grounding, and the calculation flow of the grounding resistance of the cable core is entered:
Further, when the bus voltage of the bus anode is Um is justOr the bus voltage of the bus cathode is Um is minusOr the voltage U at two open ends measured by the open element linear optical coupling sampling moduleOpening nWhen the alternating current component is larger than a set value, reporting alternating current entering; if a certain opening element U is presentOpening nHas an alternating current component greater than Um is just，Um is minusThe alternating current component of (a) is judged as interference entering from the open element, otherwise, the alternating current component of (b) is judged as interference entering from the bus.
Further, when the anode of the bus is judged to be grounded, the action voltage of all the switching-in elements is actively increased or the anti-jitter time delay of the switching-in elements is increased according to the setting; when the negative pole of the bus is grounded and a selected line is grounded out of a branch of a certain optical coupling external cable core, the action voltage of the switching-in element is actively increased or the anti-jitter delay of the switching-in element is increased according to the setting, and even the switching-in element is locked.
Further, when the interference enters from the bus, the action voltage of all the switching-in elements is actively increased or the anti-jitter time delay of the switching-in elements is increased according to the setting; when the open-in element is judged to enter, the action voltage of the open-in element is actively increased or the anti-jitter time delay of the open-in element is increased according to the setting.
Further, when it is determined that interference enters from the bus or the open element, a filtering function is added according to the setting, and the alternating current component is filtered to avoid the influence of the alternating current interference on the open element.
Compared with the prior art, the invention has the beneficial effects that:
1. and by adopting the DC/DC power supply module, the abnormal mutual interference between the protection device and the DC system is avoided, and the ground capacitance of the DC system is reduced.
2. An insulation monitoring function is added to the protection device.
3. The insulation monitoring function of the protection device can effectively detect the insulation state of each optical coupling external cable core branch.
4. The voltage at two ends of the switch-in element is measured by adopting a linear optical coupler, and the branch resistance of the cable core is calculated by utilizing the relation between the voltage at two ends of the switch-in element and the system voltage, so that the sensitivity of the branch resistance is greatly improved.
5. The voltage at two ends of the open-circuit element is used for effectively monitoring the alternating current interference entering from the open-circuit element.
6. And calculating the resistance of the positive electrode and the negative electrode to the ground by utilizing a switching bridge technology.
7. Active precaution measures are adopted, and protection maloperation caused by insulation abnormity, alternating current channeling and the like is effectively prevented.
Drawings
FIG. 1 is a schematic diagram of the external port wiring components of a prior art protective and automation device;
FIG. 2 is a schematic diagram of a conventional open-circuit voltage regulator tube;
FIG. 3 is a schematic diagram of a triode open circuit;
fig. 4 is a schematic diagram illustrating a control protection system with insulation monitoring and active guarding functions according to an embodiment of the present invention;
FIG. 5 is a schematic diagram of a linear optocoupler sampling module of an open-in element;
FIG. 6 is a schematic diagram of the insulation monitoring device;
FIG. 7 is an equivalent diagram of insulation resistance of the positive electrode and the negative electrode;
in the figure: 1. a DC/DC power supply module; 2. an input element linear optical coupling sampling module; 3. an insulation monitoring device; 21. a linear resistance voltage division unit; 22. a capacitive filtering unit; 23. a linear optocoupler sampling unit; 24. a digital-to-analog conversion unit; 31. a bus voltage monitoring module; 32. a bus voltage monitoring module; 33. and detecting a bridge resistance module.
Detailed Description
The present invention will be described in further detail with reference to the accompanying drawings and detailed description.
Example (b):
referring to fig. 4, the protection system with insulation monitoring and active precaution functions provided in this embodiment includes a DC/DC power module 1, an open-circuit element linear optocoupler sampling module 2, and an insulation monitoring device 3.
Wherein, the input end of the DC/DC power module 1 is connected with a power supply, and the output end is connected with a power interface of an input port of an input element; that is, the power supply of the input port of the switching value is connected to the output end of the DC/DC power module 1, so that the external cables of the set of protection and automation equipment all use the power supply after protected DC/DC isolation conversion, and the protected external cables are thoroughly isolated from the direct current system, thereby avoiding mutual interference influence of the external cables and simultaneously reducing the ground capacitance of the direct current system; when the external loop cable of the secondary equipment is grounded, the insulation monitoring device cannot effectively detect, and at the moment, the protection device is required to monitor all insulation states of the secondary equipment, so that the open-in element linear optical coupler sampling module 2 is used for monitoring voltages at two ends of the open-in element, judging whether the open-in element is open or not and monitoring the voltage U of the open-in elementOpening nAnd n is a positive integer.
The insulation monitoring device 3 is connected to a circuit connected with the output end of the DC/DC power module 1 and a power interface of the input port of the switching-in element, and is used for detecting and judging whether the positive electrode and the negative electrode of the bus operate normally or not, starting a bus ground resistance detection process when the negative electrode and the positive electrode are grounded, calculating the bus ground resistance, starting a branch circuit selection function, and performing a ground resistance calculation process after a fault branch circuit is selected.
Specifically, as shown in fig. 5, the open-element linear optocoupler sampling module 2 includes a linear resistance voltage division unit 21, a capacitance filtering unit 22, a linear optocoupler sampling unit 23, and a digital-to-analog conversion unit 24, which are connected in sequence; the linear resistance voltage division unit 21 is used for adjusting the current flowing through the linear optocoupler sampling unit to a linear region of the linear optocoupler, and can also be used as a tool for adjusting power; the linear optocoupler sampling unit 23 is configured to collect a current flowing through the linear optocoupler, and convert the current into an analog quantity adapted by the digital-to-analog conversion unit 24; the digital-to-analog conversion unit 24 is configured to convert the analog quantity converted by the linear opto-coupler sampling unit into a digital quantity for output, determine whether an alternating current ingress exists according to the converted digital quantity, and calculate an ingress interference voltage of the alternating current ingress. In addition, the capacitance filtering unit 22 is connected in series between the linear resistance voltage dividing unit 21 and the linear optical coupling sampling unit 23, so as to prevent abnormal interference from entering the linear optical coupling sampling unit 23, that is, the capacitance filtering unit 22 is mainly used as a hardware-level anti-interference measure for opening, thereby preventing the influence of high-frequency interference on the linear optical coupling sampling module of the opening element, which can contain capacitance, and can be used as a filtering channel of high-frequency interference, and also can be added with elements such as a diode, and prevent abnormal interference from entering the linear optical coupling sampling unit 23, so as to improve the accuracy of measurement.
As shown in fig. 6, the insulation monitoring device 3 includes bus voltage monitoring modules 31 and 32 and a detection bridge resistance module 33; one end of a bus voltage monitoring module 31 is connected to the positive bus, and the other end is grounded; one end of the other bus voltage monitoring module 32 is connected to the negative bus, and the other end is grounded; one end of the detection bridge resistance module 33 is connected to the negative bus, and the other end is grounded through the disconnecting switch K. Of course, the structural principle of the bus voltage monitoring modules 31 and 32 is completely the same as that of the open-element linear optocoupler sampling module 2, and will not be described herein again.
Specifically, the above insulation monitoring device 3 detects and judges whether the positive electrode and the negative electrode of the bus normally operate in the following manner:
the resistance of the linear resistance voltage division unit is R1, the resistance of the detection bridge resistance module is R2, and the equivalent grounding resistance of the positive electrode of the direct current bus is Rm+The equivalent grounding resistance of the cathode of the direct current bus is Rm-When the device normally operates, the disconnecting link K is disconnected;
when in normal operation, the bus voltage of the bus anode is Um is just,
When in normal operation, the bus voltage of the bus cathode is Um is minus，
When the circuit normally operates, the voltage at two open ends measured by the open element linear optocoupler sampling module is UOpening n,
Normal operation, no abnormal insulation, Um is just＝Um is minus；
And (3) judging the grounding resistance of the bus:
when U is turnedm is just>Um is minusAnd the difference exceeds a set value (e.g., U)m is just-Um is minus>10％(Um is just+Um is minus) ) the negative electrode is judged to be grounded;
when U is turnedm is minus>Um is justAnd the difference exceeds a set value (e.g., U)m is minus-Um is just>10％(Um is just+Um is minus) ) the positive electrode is judged to be grounded;
when the anode is grounded or the cathode is grounded, or the insulation resistance calculation process is started within a set time point every day,
before K switching on, the bus voltage of the bus anode is Um is 1The bus voltage of the bus cathode is Um minus 1，
After K switching on, the bus voltage of the bus anode is Um is 2The bus voltage of the bus cathode is Um minus 2，
When K is not closed, as shown in fig. 7:
closing K, at the moment
From the above formula, the insulation resistance of the positive electrode and the negative electrode can be calculated.
When the resistance between the positive electrode and the negative electrode is smaller than the resistance of the linear resistance voltage division module, the positive electrode and the negative electrode are simultaneously grounded.
The existing insulation monitoring device can only select a line to a certain protection screen, but specific cable core branch in the protection screen cannot be searched, and the specific cable core branch can only be searched by a direct-current grounding searching instrument manually. In order to solve this problem, the following method is adopted in this embodiment:
and starting a branch line selection function when the system cathode is grounded and the system anode is grounded, and checking the voltage at two ends of each switch-in element.
When U is turnedn＝UNegative poleAnd then, the cable core branch is considered to be in metallic grounding.
When U is turnedn<UNegative poleAnd greater than a predetermined interference value, e.g. 20% UNegative poleAnd if so, determining that the cable core branch has resistance grounding. And entering a cable core grounding resistance judgment flow.
In order to prevent protection misoperation caused by grounding of an external cable, the existing microcomputer protection needs to adopt complex setting to adjust the action voltage of an optical coupler to be more than 55% Un and less than 70% Un; and each optical coupling branch increases anti-shake time delay. However, the dc system is complex, and the dc system bus often has a phenomenon of voltage deviation to ground, for example, the dc system is poorly insulated, the positive electrode is grounded via a high resistance, which will cause the voltage to ground of the negative electrode bus to rise, and set higher than the action voltage of the optocoupler, and when the external cable of the optocoupler is grounded again, the instantaneous voltage is higher than the action voltage, and the holding time is longer as the capacitance to ground of the dc system is larger, which may exceed the anti-jitter delay, thereby causing protection malfunction. Therefore, there are the following problems:
1) any point of the dc system is grounded and the insulation is poor, which affects all the protection devices connected to the dc system.
2) The capacitance to ground of the direct current system is very large, which causes the interference duration to be long and the prevention to be difficult.
3) When the insulation of the direct current system is abnormal, the protection device cannot take any active measures to prevent the occurrence of protection misoperation.
Therefore, in order to solve such problems, the present invention takes the following measures:
1) and by adopting the DC/DC power supply module, the abnormal mutual interference between the protection device and the DC system is avoided, and the ground capacitance of the DC system is reduced.
2) When the protection is judged to be abnormal, the following active measures are taken:
A. when the anode is grounded, the operation voltage of all the switching elements can be actively increased or the anti-jitter time delay can be increased according to the setting.
B. When the negative pole is grounded and a selected line is grounded out of a certain optical coupling external cable core branch, the action voltage of the switching-in element can be actively increased or the anti-jitter delay of the switching-in element can be increased according to the setting, and even the switching-in element is locked.
Specifically, the insulation monitoring device 3 detects and judges whether there is a behavior of ac ingress:
when the bus voltage of the bus anode is Um is justOr the bus voltage of the bus cathode is Um is minusOr the voltage U at two ends of the open-in element measured by the open-in element linear optical coupling sampling moduleOpening nWhen the alternating current component is larger than a set value (such as 10V), the alternating current is reported to enter. If a voltage U is present across one of the switching elementsOpening nHas an alternating current component greater than Um is just，Um is minusThe ac component of (2) is determined as interference entering from the entry element. Otherwise, judging that interference enters from the bus.
When the interference is judged to enter from the bus, the action voltage of all the switching-in elements is actively increased or the anti-jitter time delay of the switching-in elements is increased according to the setting; when the open-in element is judged to enter, the action voltage of the open-in element is actively increased or the anti-jitter time delay of the open-in element is increased according to the setting.
When the interference enters from the bus or the open-circuit element, the filtering function is added according to the setting, and the alternating current component is filtered to avoid the alternating current interference to the open-circuit element.
In summary, compared with the prior art, the protection system with insulation monitoring and active precaution functions provided by this embodiment has the following technical advantages:
1. and by adopting the DC/DC power supply module, the abnormal mutual interference between the protection device and the DC system is avoided, and the ground capacitance of the DC system is reduced.
2. An insulation monitoring function is added to the protection device.
3. The insulation monitoring function of the protection device can effectively detect the insulation state of each optical coupling external cable core branch.
4. The voltage at two ends of the switch-in element is measured by adopting a linear optical coupler, and the branch resistance of the cable core is calculated by utilizing the relation between the voltage at two ends of the switch-in element and the system voltage, so that the sensitivity of the branch resistance is greatly improved.
5. The voltage at two ends of the open-circuit element is used for effectively monitoring the alternating current interference entering from the open-circuit element.
6. And calculating the resistance of the positive electrode and the negative electrode to the ground by utilizing a switching bridge technology.
7. Active precaution measures are adopted, and protection maloperation caused by insulation abnormity, alternating current channeling and the like is effectively prevented.
The above embodiments are only for illustrating the technical concept and features of the present invention, and the purpose thereof is to enable those skilled in the art to understand the contents of the present invention and implement the present invention accordingly, and not to limit the protection scope of the present invention accordingly. All equivalent changes or modifications made in accordance with the spirit of the present disclosure are intended to be covered by the scope of the present disclosure.
Claims (8)
1. A control protection system with insulation monitoring and active precaution functions is characterized by comprising a DC/DC power supply module, an open-in element linear optocoupler sampling module and an insulation monitoring device;
the output end of the DC/DC power supply module is connected with a power supply interface of the input port of the switching-in element;
the linear optocoupler sampling module of the open-in element is used for monitoring the voltage of the input port of the open-in element, judging whether the open-in element is open or not and monitoring the voltage U of the open-in elementOpening nN is a positive integer;
the insulation monitoring device is connected to a circuit connected with the output end of the DC/DC power supply module and a power supply interface of the input port of the switching-in element and used for detecting and judging whether the positive electrode and the negative electrode of the bus run normally or not, when the negative electrode and the positive electrode are judged to be grounded, a bus ground resistance detection process is started, a bus ground resistance is calculated, then a branch line selection function is started, and a ground resistance calculation process is carried out after a fault branch is selected;
the insulation monitoring device comprises two bus voltage monitoring modules and a detection bridge resistance module; one end of a bus voltage monitoring module is connected to the positive bus, and the other end of the bus voltage monitoring module is grounded; one end of the other bus voltage monitoring module is connected to the negative bus, and the other end of the other bus voltage monitoring module is grounded; one end of the detection bridge resistance module is connected to the negative bus, and the other end of the detection bridge resistance module is grounded through the disconnecting link switch;
the bus voltage monitoring module and the open-in element linear optical coupling sampling module have the same structure and respectively comprise a linear resistance voltage division unit, a capacitance filtering unit, a linear optical coupling sampling unit and a digital-to-analog conversion unit which are sequentially connected; the linear resistance voltage dividing unit is used for adjusting current flowing through the linear optocoupler to a linear area of the linear optocoupler, the capacitance filtering unit is used for preventing abnormal interference from entering the linear optocoupler sampling unit, the linear optocoupler sampling unit is used for collecting current flowing through the linear optocoupler and converting the current into analog quantity adaptive to the digital-to-analog sampling unit, the digital-to-analog conversion unit is used for converting the analog quantity converted by the linear optocoupler into digital quantity, judging whether alternating current channeling exists according to the converted digital quantity and calculating interference voltage of the alternating current channeling.
2. The control protection system with insulation monitoring and active precaution functions as claimed in claim 1, wherein the insulation monitoring device detects whether the positive and negative poles of the bus are normally operated in a manner that:
wherein, the resistance of the linear resistance voltage dividing unit is R1The resistance of the detection bridge resistance module is R2When the device is in normal operation, the disconnecting link is disconnected;
when in normal operation, the bus voltage of the bus anode is Um is just,
When in normal operation, the bus voltage of the bus cathode is Um is minus，
When the device is in normal operation, the voltage at the two ends of the switch-in measured by the switch-in measuring module is UOpening n,
Normal operation, no abnormal insulation, Um is just＝Um is minus；
When U is turnedm is just>Um is minusIf the difference exceeds the first set value, the cathode is judged to be grounded;
when U is turnedm is minus>Um is justAnd if the difference exceeds a second set value, the anode is judged to be grounded.
3. The control protection system with insulation monitoring and active precaution functions as claimed in claim 2, wherein the insulation monitoring device starts the bus line to ground resistance detection process in a manner that: firstly, recording the bus voltage before and after the knife switch is switched on, and calculating the bus ground resistance according to the change of the bus voltage;
the resistance to ground of the positive electrode of the bus is Rm+The resistance to ground of the negative electrode of the bus is Rm-；
Before the knife switch is switched on, the bus voltage of the bus anode is Um is 1The bus voltage of the bus cathode is Um minus 1，
After the knife switch is switched on, the bus voltage of the bus anode is Um is 2The bus voltage of the bus cathode is Um minus 2，
Then
4. The control and protection system with insulation monitoring and active precaution functions as claimed in claim 2, wherein the insulation monitoring device activates the branch line selection function by:
when U is turnedOpening n＝Um is minusThen, the cable core is consideredBranch metallic grounding;
when U is turnedOpening n<Um is minusAnd when the interference value is larger than the set interference value, the cable core branch is considered to have resistance grounding, and the calculation flow of the grounding resistance of the cable core is entered:
5. The control protection system with insulation monitoring and active guarding functions as claimed in claim 2, wherein when the bus voltage of the bus positive electrode is Um is justOr the bus voltage of the bus cathode is Um is minusOr the voltage U at two open ends measured by the open element linear optical coupling sampling moduleOpening nWhen the alternating current component is larger than a set value, reporting alternating current entering; if a certain opening element U is presentOpening nHas an alternating current component greater than Um is just，Um is minusThe alternating current component of (a) is judged as interference entering from the open element, otherwise, the alternating current component of (b) is judged as interference entering from the bus.
6. The control protection system with insulation monitoring and active precaution functions as claimed in claim 1, wherein when the positive electrode of the bus is judged to be grounded, the operating voltages of all the switching elements are actively increased or the anti-jitter delay is increased according to the setting; and when the negative pole of the bus is grounded and a selected line is grounded out of a branch of a certain optical coupling external cable core, actively increasing the action voltage of the switching-in element or increasing the anti-jitter delay of the switching-in element or locking the switching-in element according to the setting.
7. The control protection system with insulation monitoring and active precaution functions as claimed in claim 5, wherein when it is determined that ac interference enters from the bus, the operating voltage of all the open-in components is actively increased or the anti-jitter delay is increased according to the setting; and when the input element is judged to enter, actively increasing the action voltage of the input element or increasing the anti-jitter time delay of the input element according to the setting.
8. The control protection system with insulation monitoring and active precaution functions as claimed in claim 5, wherein when it is determined that interference enters from the bus or the entry element, a filtering function is added according to the setting to filter the AC component to avoid the influence of the AC interference on the entry element.
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