CN108832624A - Voltage security parallel device - Google Patents

Abstract

The invention discloses a kind of voltage security parallel devices, including power conversion module, voltage acquisition module, Logic control module, relay arranged side by side, voice module, touch screen.The present invention can be achieved voltage it is arranged side by side before, neutralize side by side after off-the-line overall process is anti-error and monitoring function; be only voltage simultaneously/off-the-line execute-in-place, maintenance provide safe related function protection; simultaneously live acousto-optic and message security warning are provided, can effectively prevent voltage simultaneously/off-the-line maloperation event；Its respective logic incorporates substation's integrated diagnostic system, it can be achieved that operation backstage and monitoring center real-time monitoring warning information function simultaneously.

Description

Voltage Safe Parallel Device

technical field

The invention relates to the technical field of substation comprehensive automation control, in particular to a voltage safety parallel device.

Background technique

When a section of the bus voltage is overhauled or faulty, the voltage needs to be paralleled to ensure the normal operation of the busbar protection and metering devices in the overhaul section. At the same time, in order to prevent personal casualties and equipment damage caused by reverse power transmission, when the voltages are paralleled, the equipment needs to be paralleled for the first time, and then paralleled for the second time.

Due to problems such as wiring errors, secondary parallel relay contact adhesion, and voltage imbalance in the substation site, and the voltage parallel operation only depends on the experience of personnel, it is very easy to have abnormal voltage parallel conditions, causing the secondary voltage to be sent back to the maintenance side. If it is light, it will cause the air breaker to trip and damage the equipment, and if it is serious, it will cause casualties on the scene.

The existing voltage parallel devices mainly have the following deficiencies:

One is that the existing device can only be paralleled once after the equipment is paralleled, and can be paralleled for the second time; it cannot take into account the factors that prohibit paralleling such as voltage imbalance in any section, that is, it cannot realize the logical blocking function of safe paralleling.

Second, the existing device can only display the two states of normal paralleling and normal decoupling; it cannot realize on-site permission/prohibition of parallel acousto-optic warnings before operation, nor can it realize acousto-optic warnings such as abnormal paralleling and abnormal decoupling after operation .

The third is that the signal light of the existing device is red and green, and there is no audible and visual alarm for abnormal conditions in the substation site. It is only checked by the on-site operation and maintenance/maintenance personnel. It is not easy to attract attention during the inspection operation, and it cannot be uploaded in the operation background and monitoring center. Abnormal packets are monitored in real time, resulting in frequent incidents of reverse power transmission.

Contents of the invention

The purpose of the present invention is to prevent on-site personnel from making mistakes in voltage paralleling/disconnecting operations, and to provide a voltage safety paralleling device that can effectively ensure the safety of on-site personnel and equipment, has good stability, and can realize safety error prevention and sound and light alarms.

The technical solution for realizing the object of the present invention is: a voltage safety parallel device, including a power conversion module, a voltage acquisition module, a logic control module, a parallel relay, a voice module and a touch screen;

The power conversion module converts AC 220V to DC ±24V for voltage acquisition module, logic control module, parallel relay, voice module and touch screen;

There are two voltage acquisition modules, which are respectively used to collect the secondary voltage of the voltage transformers of sections I and II, calculate the phase-to-phase voltage difference and the voltage difference between the two bus sections, and send the results to the logic control module;

The logic control module makes a comprehensive judgment on the voltage collection data and switch displacement information, and compares them with the set threshold value to realize the logic judgment and threshold value comparison of the unbalanced voltage before paralleling, the voltage vector in parallel and the voltage vector after decoupling, Realize the abnormal voltage monitoring and signaling function of unbalanced voltage exceeding the limit prohibiting paralleling, during paralleling and after decoupling;

The parallel relay realizes the parallel function of the voltage-changing secondary voltage when the conditions are met, and at the same time the auxiliary contact is closed, and the parallel indicator light is lit;

The voice module performs the corresponding voice alarm function according to the different logic of the logic control module;

The touch screen is used for real-time monitoring of two busbar voltages, switch and knife switch auxiliary contacts, unbalanced voltage, and voltage difference between the same phases. The alarm information window displays alarm information, and the record query page can search for previous alarm records.

The logic control module includes a voltage vector comparison module, a three-phase voltage unbalance module and an audible and visual alarm module;

The voltage vector comparison module includes a first AND gate, a first OR gate, a second OR gate and a second AND gate, wherein the three input terminals of the first AND gate and the second OR gate are all inverted;

The three-phase voltage unbalance module includes the third OR gate; the sound and light alarm module includes the third AND gate, the fourth OR gate, the fourth AND gate, the fifth AND gate, the sixth AND gate, the seventh AND gate and the NOT gate;

voltage vector comparison module, according to Carry out the vector comparison and judgment between the same phase of the two busbars, X=A, B, C, when the three-phase vector comparison values of the two busbar voltages are greater than or equal to the threshold, the first AND gate outputs 1, which is used as the opening condition of the fourth AND gate ; When any phase-to-phase vector comparison value is less than the threshold, the first OR gate outputs 1 as the opening condition of the fifth AND gate; when any phase-to-phase vector comparison value is greater than or equal to the threshold value, the second OR gate outputs 1 as the sixth AND gate The open-in condition of the gate; the comparison values of the three-phase vectors are all less than the threshold value, and the second AND gate outputs 1, which is used as the open-in condition of the seventh AND gate; X refers to any item of the three-phase voltage ABC of the busbar in section I, and X' refers to Any one of the three-phase voltage ABC of the second-section busbar,

Three-phase voltage unbalance module, according to Compare the difference between any two phases of the same section of the bus, and then perform an OR operation with the difference between any two phases of the other section of the bus. When the voltage of any section of the bus is unbalanced and exceeds the limit, the third OR gate output is set to 1, and the parallel signal is strictly prohibited. , parallel operation of blocking voltage;

The acousto-optic alarm module accepts the input of the voltage vector comparison module and the signal of the three-phase voltage unbalanced module, and makes a logical judgment; when the output of the third OR gate is set to 1, it sends out an acousto-optic alarm signal strictly prohibited in parallel; when the third OR gate is set to 0 When the NOT gate is set to 1, an audible and visual alarm signal can be paralleled; when the fourth AND gate is set to 1, an audible and visual alarm signal for normal decoupling is issued; when the fifth AND gate is set to 1, an audible and visual alarm signal for abnormal decoupling is issued signal; when the sixth AND gate is set to 1, an abnormal parallel acousto-optic alarm signal is sent; when the seventh AND gate is set to 1, a normal parallel acousto-optic alarm signal is sent.

Compared with the prior art, the present invention has the remarkable advantages of:

(1) The present invention not only provides safety logic error prevention functions for on-site operators, maintenance personnel, etc., eliminates voltage error merge/disconnect operation events, but also provides on-site acousto-optic comprehensive safety warnings;

(2) The present invention integrates the logic into the comprehensive diagnosis system of the substation to realize the real-time monitoring function of the operation background and the monitoring center, that is, the parallel information of the voltage is displayed in the alarm window of the operation background in the form of text or a light plate, and uploaded to the monitoring center through the network for real-time monitoring. Monitoring, in order to detect abnormal conditions such as parallel/disconnection operations in time, and remind the on-site staff to avoid casualties and equipment damage caused by reverse power transmission;

(3) The present invention fills the gap in the substation voltage parallel/disconnect monitoring system through the two-stage voltage amplitude and phase comparison analysis criteria, which is of great significance for realizing intelligent diagnosis and program operation of the substation.

Description of drawings

Figure 1 is a schematic diagram of the voltage safety parallel device system.

Fig. 2 is a logic diagram of a voltage safety parallel device.

Fig. 3 is a schematic diagram of obtaining three-phase voltages of two bus sections from the "three-phase voltage acquisition module".

Fig. 4 is a schematic diagram of calculating the three-phase unbalanced voltage and the voltage difference between two sections of busbars.

Figure 5 is a schematic diagram of sending calculation results to the "logic controller".

Fig. 6 is a logic diagram of the three-phase unbalanced voltage and the same-phase voltage vector difference of the bus.

Fig. 7 is a logic diagram of anti-mistake checking before juxtaposition.

Fig. 8 is a judging basis diagram after juxtaposition.

Fig. 9 is a detection logic diagram after juxtaposition.

Fig. 10 is a judgment basis diagram after sorting out.

Fig. 11 is a logic diagram of disassembly detection.

Figure 12 is a logic diagram of the use of the skip switch.

Detailed ways

With reference to Figure 1, a voltage safety parallel device includes a power conversion module, a voltage acquisition module, a logic control module, a parallel relay, a voice module and a touch screen;

The power conversion module converts AC 220V to DC ±24V for voltage acquisition module, logic control module, parallel relay, voice module and touch screen;

There are two voltage acquisition modules, which are respectively used to collect the secondary voltage of the voltage transformers of sections I and II, calculate the phase-to-phase voltage difference and the voltage difference between the two bus sections, and send the results to the logic control module;

The logic control module makes a comprehensive judgment on the voltage collection data and switch displacement information, and compares them with the set threshold value to realize the logic judgment and threshold value comparison of the unbalanced voltage before paralleling, the voltage vector in parallel and the voltage vector after decoupling, Realize the abnormal voltage monitoring and signaling function of unbalanced voltage exceeding the limit prohibiting paralleling, during paralleling and after decoupling;

The parallel relay realizes the parallel function of the voltage-changing secondary voltage when the conditions are met, and at the same time the auxiliary contact is closed, and the parallel indicator light is lit;

The voice module performs the corresponding voice alarm function according to the different logic of the logic control module;

The touch screen is used for real-time monitoring of two busbar voltages, switch and knife switch auxiliary contacts, unbalanced voltage, and voltage difference between the same phases. The alarm information window displays alarm information, and the record query page can search for previous alarm records.

Combined with Figure 2, the logic control module includes a voltage vector comparison module, a three-phase voltage unbalance module and an audible and visual alarm module;

The voltage vector comparison module includes the first AND gate 1, the first OR gate 2, the second OR gate 3 and the second AND gate 4, wherein the three input terminals of the first AND gate 1 and the second OR gate 3 are all inverted operation;

The three-phase voltage unbalance module includes the third OR gate 7; the sound and light alarm module includes the third AND gate 5, the fourth OR gate 6, the fourth AND gate 8, the fifth AND gate 9, the sixth AND gate 10, the seventh AND gate AND gate 11 and NOT gate 12; the three inputs of the third AND gate 5 are DL combined, 1G combined and 2G combined, and the output is used as the input of the sixth AND gate 10 and the seventh AND gate 11; the fourth OR gate The input terminal of 6 is the DL fraction, 1G fraction and 2G fraction, and the output is used as the input of the fourth AND gate 8 and the fifth AND gate 9;

voltage vector comparison module, according to Carry out the vector comparison and judgment between the same phase of the two busbars, X=A, B, C, when the three-phase vector comparison values of the two busbar voltages are greater than or equal to the threshold, the first AND gate 1 outputs 1 as the opening of the fourth AND gate 8 Entry condition; when any interphase vector comparison value is less than the threshold value, the first OR gate 2 outputs 1, which is used as the opening entry condition of the fifth AND gate 9; when any interphase vector comparison value is greater than or equal to the threshold value, the second OR gate 3 outputs 1 , as the switch-in condition of the sixth AND gate 10; the comparison values of the three-phase vectors are all less than the threshold value, and the second AND gate 4 outputs 1, which is used as the switch-in condition of the seventh AND gate 11; X refers to the three-phase voltage ABC of the first section bus Any one of the items, X' refers to any one of the three-phase voltage ABC of the second busbar,

Three-phase voltage unbalance module, according to Compare the difference between any two phase modes of the same busbar, and then perform an OR operation with the difference between any two phase modes of another busbar. When the voltage of any busbar is unbalanced and exceeds the limit, the output of the third OR gate 7 is set to 1, and paralleling is strictly prohibited. Signal, blocking voltage parallel operation;

The sound and light alarm module accepts the input of the voltage vector comparison module and the signal of the three-phase voltage unbalance module, and makes a logical judgment; When it is set to 0, the NOT gate 12 is set to 1, and an acousto-optic alarm signal can be paralleled; when the fourth AND gate 8 is set to 1, a normal decoupling acousto-optic alarm signal is issued; when the fifth AND gate 9 is set to 1, an abnormal acousto-optic alarm signal is issued; Decoupling the acousto-optic alarm signal; when the sixth AND gate 10 is set to 1, an abnormal parallel acousto-optic alarm signal is sent; when the seventh AND gate 11 is set to 1, a normal parallel acousto-optic alarm signal is sent.

(1) Three-phase voltage unbalance and same-phase voltage vector difference between buses

Inside the logic control module, the three-phase unbalanced voltage of any bus or the same-phase voltage vector difference between the buses is received, and the calculation result is compared with the set threshold for logical judgment to determine whether the limit is exceeded.

(2) Safety and anti-mistake logic judgment before juxtaposition

Inside the logic control module, according to the input status of parallel handles, firstly, according to the existing conditions, make a judgment: only when the "I section unbalanced voltage" does not exceed the limit, "II section unbalanced voltage" does not exceed the limit, and the 1G contact is closed , 2G contact closure, and DL contact closure, the five conditions must be satisfied at the same time, that is, the relationship of "and", so that they can be paralleled normally. If it is not satisfied, voice prompts and sound and light alarms will be carried out according to different situations.

(3) Judgment of normal juxtaposition and juxtaposition abnormality

The logic control module monitors the voltage after paralleling, and then compares it with a preset threshold, as a basis for judging whether the paralleling is successful after paralleling. If the conditions are met, the system will send a "normal parallel" voice prompt to the operator. Otherwise an "unusual tie" is reported.

(4) Judgment of normal disassembly and disassembly abnormality

The logic control module also has a monitoring function for the disassembly, and makes a logical judgment on whether the system is normally disassembled. Logical judgment is made on the normal voltage disconnection and abnormal disconnection after disconnection. If both are satisfied, the normal disconnection state is determined; if any condition is not satisfied, an abnormal disconnection alarm will be triggered and a warning light will be output.

(5) Anti-mistaken unlocking function

This device is equipped with an unlock switch (X001), which can be used to cross the unbalanced voltage and prohibit parallel logic judgments when the system fails, and force the parallel connection. At this time, the error prevention and monitoring functions will be lost, so be careful when it is not necessary use.

Note: Skip protection can only skip the safety and anti-malfunction function of any bus voltage unbalanced limit, and it cannot be paralleled when 1G, 2G, and DL are not closed.

The present invention will be described in detail below in conjunction with examples.

Example

In conjunction with Fig. 1, a voltage safety parallel device for safety error prevention and sound and light alarm of the present invention includes a power conversion module, a voltage acquisition module, a logic control module, a parallel relay, a voice module, and a touch screen;

1. The power conversion module converts AC 220V to DC ±24V for voltage acquisition, logic control, parallel relay, voice module and touch screen;

2. There are two voltage acquisition modules, which are respectively used to collect the secondary voltage of the voltage transformers of sections I and II, calculate the phase-to-phase voltage difference of the two busbars and the voltage difference between the busbars, and transmit them to the touch screen through the RS485 interface, and the touch screen reads the voltage After the value, in addition to providing the display function of the interface, it is sent to the "logic control module", as shown in Figure 3-5.

3. The working principle and specific program of the logic control module: the logic control module makes a comprehensive judgment on the voltage collection data and the switch value displacement information, and compares it with the set threshold value, which can realize the voltage imbalance before paralleling, the voltage vector and the voltage vector during paralleling The voltage vector logic judgment and threshold value comparison after decoupling can realize the voltage abnormality monitoring and signaling function of prohibiting paralleling when the unbalanced voltage exceeds the limit, during paralleling and after decoupling;

3.1 Three-phase voltage unbalance and same-phase voltage vector difference logic between buses

Inside the "logic control module", the calculation result is compared with the set threshold to obtain the signal logic of whether the three-phase unbalanced voltage of any bus or the same-phase voltage vector difference between buses exceeds the limit. As shown in Figure 6.

3.2 Anti-false logic judgment before juxtaposition

Inside the logic control module, according to the input state of the parallel handle, firstly, according to the existing conditions, judgment is made. Parallels are allowed if the conditions are met. If it is not satisfied, voice prompts and sound and light alarms will be given according to different situations. As shown in Figure 7.

According to Figure 7, it can be known that only when the "I segment unbalanced voltage" does not exceed the limit, the "II segment unbalanced voltage" does not exceed the limit, the 1G contact is closed, the 2G contact is closed, and the DL contact is closed, the five conditions are all at the same time Satisfied, that is, the relationship of "AND", can perform parallel operation. In the third OR gate 7, when the three-phase unbalanced voltage of any bus bar exceeds the limit, parallel connection is strictly prohibited and the parallel logic entrance will be closed.

3.3 Logical Judgment of Normal Parallel and Abnormal Parallel

The logic control module will also monitor the voltage after paralleling, and then compare it with a preset threshold value as a basis for judging whether the paralleling is successful after paralleling. If the conditions are met, the system will send a "normal parallel" voice prompt to the operator. Otherwise an "unusual tie" is reported. As shown in Figure 8 and Figure 9:

According to the first line of Figure 9, it can be seen that after paralleling, the voltages represented by M111, M112, and M113 do not exceed the threshold, and the 1G, 2G, and DL contacts are all closed, which is the "AND" logic judgment of the six conditions , to judge normal juxtaposition. Otherwise, as shown in Figure 9, one of the following conditions is not satisfied, that is, the "or" logic, which will cause abnormal parallel alarms.

3.4 Logical judgment of normal disconnection and abnormal disconnection

The logic control module also has a monitoring function for de-loading, and judges whether the system is de-loading normally. The judging process is to measure the voltage after unloading. See if the threshold is exceeded. The comparison logic is shown in Figure 10:

At the same time, according to the above logic after unloading, the judgment of normal unloading and abnormal unloading is carried out, and prompts are given by voice and sound and light. The logic process is shown in Figure 11.

After decoupling, make an "AND" logic judgment on the disconnection of M114, M115, M116 and 1G, 2G, DL contacts. If they are all satisfied, then determine the normal decoupling state. If the voltage does not exceed the threshold, it will trigger an abnormal deloading alarm and output a warning light.

3.5 About the function of preventing accidental unlocking

The logic control module is equipped with an unlock switch (X001), which can be used to prohibit the parallel logic across the unbalanced voltage when the system fails, and force the parallel connection. At this time, the error prevention and monitoring functions will be lost, so use it with caution when it is not necessary . The logic is shown in Figure 12:

Skip protection can only skip the safety and anti-malfunction function of any bus voltage unbalanced limit, and it cannot be paralleled when 1G, 2G, and DL are not closed.

4. Parallel relay working process and signal

When phase A of bus I and bus II has voltage, the voltage indicators of bus I and bus II on the external panel of the device light up, and the logic controller makes a logical judgment. Section unbalanced voltage" does not exceed the limit, 1G contact is closed, 2G contact is closed, and DL contact is closed. When any of the five conditions does not meet, it is forbidden to parallel, then the alarm indicator light on the panel is lit, and the display Display warning information; when the five conditions are met at the same time, normal juxtaposition is allowed.

At this time, turn the parallel handle on the external panel of the device to the parallel position, the parallel relay coil is energized, and the three internal normally open auxiliary contacts are closed, realizing the secondary voltage parallel, and at the same time the parallel indicator light on the external panel of the device is lit. At this time, the logic controller makes logical judgments in parallel, determines normal parallel or abnormal parallel, and gives audible and visual indication;

Turn the parallel handle on the external panel of the device to the decoupling position, the parallel relay coil is de-energized, the internal normally open auxiliary contact is disconnected, and the voltage is decoupled for the second time; at the same time, the parallel indicator light on the external panel of the device goes out. At this time, the logic controller makes a logical judgment after unloading, determines whether the unloading is normal or abnormal, and gives an audible and visual indication;

The present invention can realize following function:

(1) Anti-misoperation locking function of voltage safety parallel device

When the primary devices such as DL close, 1G close, and 2G close are paralleled, the logic controller can monitor and judge the logic of the three-phase voltage unbalance before paralleling, only when the "I stage unbalanced voltage" does not exceed Limit, "II stage unbalanced voltage" does not exceed the limit, 1G contact closure, 2G contact closure, DL contact closure, five conditions are met at the same time, that is, the relationship of "and", can be paralleled normally, otherwise not Parallel, concurrent prohibition of parallel audible and visual alarms and message display and recording on the display screen.

(2) Whole-process monitoring of voltage safety parallel devices

During the paralleling process, turn the operating handle to the paralleling position, the paralleling relay coil is energized, and the three internal normally open auxiliary contacts are closed, realizing the secondary voltage paralleling, and the paralleling indicator light is on at the same time. At this time, the logic controller makes a logical judgment in paralleling, determines normal paralleling or abnormal paralleling, and can perform sound and light indication.

After the decoupling operation, the parallel handle is turned to the decoupling position, the parallel relay coil is de-energized, the internal normally open auxiliary contact is disconnected, the voltage is decoupled twice, and the parallel indicator light is turned off at the same time. At this time, the logic controller makes logical judgment after unloading, determines whether unloading is normal or abnormal, and can perform acousto-optic indication.

(3) Anti-mistaken unlocking function of voltage safety parallel device

This controller is equipped with an unlock switch, which can be used to prohibit the parallel logic across the unbalanced voltage when the system fails, and force the parallel connection. At this time, the error prevention and monitoring functions will be lost, but it can only skip any bus voltage. The safety error prevention function of balance over limit cannot be paralleled when 1G, 2G, and DL are not closed.

(4) Station terminal voltage safety parallel/disconnect anti-mistake and monitoring function

The logic of the voltage safety parallel device shown in Figure 2 is fused with the digital voltage, DL, 1G, 2G, and BK signals in the substation into a substation voltage safety parallel/disconnect error prevention and monitoring system, which can realize voltage safety parallel/disconnect operations in the operation background , and continuously monitor its operation status, inform the on-site operation, maintenance and other staff in real time, effectively ensure the safe operation of personal and equipment, and improve the comprehensive intelligent diagnosis system for safe operation of substations.

Claims (4)

1. A voltage safety parallel device, characterized in that, comprises a power conversion module, a voltage acquisition module, a logic control module, a parallel relay, a voice module and a touch screen; The power conversion module converts AC 220V to DC ±24V for voltage acquisition module, logic control module, parallel relay, voice module and touch screen; There are two voltage acquisition modules, which are respectively used to collect the secondary voltage of the voltage transformers of sections I and II, calculate the phase-to-phase voltage difference and the voltage difference between the two bus sections, and send the results to the logic control module; The logic control module makes a comprehensive judgment on the voltage collection data and switch displacement information, and compares them with the set threshold value to realize the logic judgment and threshold value comparison of the unbalanced voltage before paralleling, the voltage vector in parallel and the voltage vector after decoupling, Realize the abnormal voltage monitoring and signaling function of unbalanced voltage exceeding the limit prohibiting paralleling, during paralleling and after decoupling; The parallel relay realizes the parallel function of the voltage-changing secondary voltage when the conditions are met, and at the same time the auxiliary contact is closed, and the parallel indicator light is lit; The voice module performs corresponding voice alarms according to different logics of the logic control module; The touch screen is used for real-time monitoring of two busbar voltages, switch and knife switch auxiliary contacts, unbalanced voltage, and voltage difference between the same phases. The alarm information window displays alarm information, and the record query page can search for previous alarm records. 2. The voltage safety parallel device according to claim 1, wherein the logic control module comprises a voltage vector comparison module, a three-phase voltage unbalance module and an audible and visual alarm module; wherein The voltage vector comparison module includes a first AND gate (1), a first OR gate (2), a second OR gate (3) and a second AND gate (4), wherein the first AND gate (1) and the second OR gate (3) The three input terminals all carry out inversion operation; The three-phase voltage unbalance module includes a third OR gate (7); the sound and light alarm module includes a third AND gate (5), a fourth OR gate (6), a fourth AND gate (8), and a fifth AND gate (9 ), the sixth AND gate (10), the seventh AND gate (11) and the NOT gate (12); the three inputs of the third AND gate (5) are DL combination, 1G combination and 2G combination, and the output is as The input of the sixth AND gate (10) and the seventh AND gate (11); the input end of the fourth OR gate (6) is DL fractionation, 1G fractionation and 2G fractionation, and the output is as the fourth AND gate (8) , the input of the fifth AND gate (9); voltage vector comparison module, according to Carry out the vector comparison judgment between the same phases of the two busbars, X=A, B, C, when the three-phase vector comparison values of the two busbar voltages are greater than or equal to the threshold, the first AND gate (1) outputs 1 as the fourth AND gate ( 8) open-in condition; when any interphase vector comparison value is less than the threshold value, the first or gate (2) outputs 1, as the open-in condition of the fifth AND gate (9); when any interphase vector comparison value is greater than or equal to the threshold value , the second OR gate (3) outputs 1 as the open-in condition of the sixth AND gate (10); the three-phase vector comparison values are all less than the threshold value, and the second AND gate (4) outputs 1 as the seventh AND gate (11 ) switch-in condition; X refers to any item of the three-phase voltage ABC of the busbar in section I, and X' refers to any item of the three-phase voltage ABC of the busbar in section II; Three-phase voltage unbalance module, according to Compare the difference between any two phases of the same section of the bus, and then perform an OR operation with the difference between any two phases of another section of the bus. When the voltage of any section of the bus is unbalanced and exceeds the limit, the output of the third OR gate (7) is set to 1, sending Parallel signals and blocking voltages are strictly prohibited to operate in parallel; The acousto-optic alarm module accepts the input of the voltage vector comparison module and the signal of the three-phase voltage unbalanced module, and makes a logical judgment; when the output of the third OR gate (7) is set to 1, an acousto-optic alarm signal is strictly forbidden to be paralleled; when the third or When the gate (7) is set to 0, the NOT gate (12) is set to 1, and an audible and visual alarm signal can be paralleled; when the fourth AND gate (8) is set to 1, a normal decoupling audible and visual alarm signal is sent; (9) When it is set to 1, an abnormal decoupling sound and light alarm signal is sent; when the sixth AND gate (10) is set to 1, an abnormal parallel sound and light alarm signal is sent; when the seventh AND gate (11) is set to 1, Issue normal parallel audible and visual alarm signals. 3. The parallel device for voltage safety according to claim 2, wherein the voice module performs a criterion according to the input of the voltage vector comparison module, the three-phase voltage unbalance over-limit module, and the trigger logic setting module, Make normal parallel, parallel abnormal, normal decoupling, decoupling abnormal, parallel prohibition speech. 4. The parallel device for voltage safety according to claim 1, wherein the voltage acquisition module sends the voltage measurement result to the touch screen through the RS485 interface, and the touch screen reads the voltage value and transmits it to the logic control module.