CN117081014A - Bus compound ratio differential protection method and device - Google Patents
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Abstract
The invention relates to a bus compound ratio differential protection method and a device, which belong to the technical field of relay protection of power systems, and the method comprises the following steps: when the bus is in a single bus state, the bus small-difference differential current, the bus small-difference compound ratio differential element and the bus differential compound voltage element take AND logic, and whether the bus trips signals are output; when the bus is in a double-bus state, the result of taking or logic of the I bus differential composite voltage element and the II bus differential composite voltage element is further summed, the result of taking or logic of the I bus small difference differential current and the II bus small difference differential current is further summed, and after taking or logic, whether a bus combined switch trips or not is output. The invention utilizes the ratio characteristics of the line multi-terminal voltage amplitude reduction and the effective distinction between the current action area and the brake area during normal operation and external short circuit to construct a differential protection method based on current and voltage, and can efficiently treat most of faults containing buses on the premise of not upgrading and reforming the existing distribution network on a large scale.
Description
Technical Field
The invention belongs to the technical field of relay protection of power systems, and particularly relates to a bus compound ratio differential protection method and device.
Background
Most of traditional power distribution systems are single-power radial networks, even if the structure is a closed-loop network, open-loop operation modes are adopted, and the power flow and the fault current of the traditional power distribution systems all have the characteristic of unidirectional flow. Therefore, the traditional power distribution network protection configuration is simpler, and the three-section type current protection can meet the requirements. However, the access of distributed power sources (DG) changes the structure of the distribution network, such that conventional distribution networks are converted into active networks. Under the novel architecture of the active distribution network, the magnitude and the direction of the power flow and the fault current are uncertain, and the sensitivity and the selectivity of the traditional three-section current protection meet important challenges. Under the new situation, a novel bus compound ratio differential protection method suitable for the active distribution network features is needed to be researched. Compared with the protection of other principles, the current differential protection can better adapt to various complex fault conditions such as power system oscillation, asymmetric short circuit and the like, is not influenced by the disconnection of a voltage transformer, and can be widely applied to the power system. In principle, the current differential protection has absolute selectivity, and is one of the most effective ways to solve the new problem of active power distribution network protection at present.
At present, unbalanced current often occurs in a circuit, so that sensitivity, rapidity and stability of bus differential protection are difficult to consider, and causes unbalanced three-phase loads of buses are caused, for example: the operation mechanism has insufficient importance for unbalanced management, high working randomness, disordered connection of single-phase electric equipment, unreasonable design of a power supply net rack, temporary power utilization, seasonal power utilization, line defect faults and the like. Meanwhile, the existing bus differential protection logic is high in complexity, the complexity of the device is easy to bring, and unstable factors are improved, so that research and development work of a novel bus compound ratio differential method and device are urgently needed to be carried out.
Disclosure of Invention
The invention aims to solve the defects of the prior art and provides a bus compound ratio differential verification method and device.
In order to achieve the above purpose, the technical scheme adopted by the invention is as follows:
a bus compound ratio differential protection method comprising:
(1) When the bus is in a single bus state, the bus small-difference differential current, the bus small-difference compound ratio differential element and the bus differential compound voltage element take AND logic, and whether the bus trips signals are output;
(2) When the buses are in a double-bus state, taking AND logic of the differential current of the small difference of the I buses, the differential element of the small difference of the I buses and the differential composite voltage element of the I buses, and outputting a bus combined switch and whether the I buses trip signals;
the differential voltage device comprises a differential voltage element, a bus combined switch and a bus tripping signal, wherein the differential voltage element is connected with the bus;
and outputting a tripping signal of the bus combined switch after taking the result of the OR logic of the I and II differential composite voltage elements and taking the result of the OR logic of the I and II differential currents.
Further, when the phase current abrupt change Id is greater than or equal to the phase current abrupt change definite value Id set Triggering a bus small-difference differential current signal; wherein Id set A value of 0.1I sum ~0.15I sum ，I sum The sum of the absolute values of all component phase current fault variation values on the bus.
Further, when the compound ratio K r Not less than complex ratio fixed value K rset Triggering a busbar small-difference compound ratio differential element signal; wherein the multiple ratio，I d The amount of operating current for differential protection,I r the amount of braking current is protected for differential motion; complex ratio constant value K rset The value is 1.15-1.4.
Further, when the bus voltage is lower than or equal to the differential protection low voltage fixed value, or when the secondary zero sequence voltage is greater than or equal to the differential protection zero sequence voltage fixed value, or the secondary negative sequence voltage is greater than or equal to the differential protection negative sequence voltage fixed value, triggering a bus differential composite voltage element signal;
wherein, the differential protection low voltage constant value takes 65% -70% PU per unit value; the differential protection zero sequence voltage constant value takes 7% -17% PU per unit value; the constant value of the differential protection negative sequence voltage takes 7% -17% of PU per unit value.
Further, when the bus is in a single bus state, the bus small-difference differential current, the bus small-difference double-ratio differential element and the bus differential composite voltage element signals are triggered, and a bus trip signal is output.
Further, when the buses are in a double-bus state, signals of the small-differential current of the I bus, the small-differential compound ratio differential element of the I bus and the differential compound voltage element of the I bus are all triggered, and a bus combined switch and an I bus tripping signal are output;
the signals of the differential current of the II buses, the differential compound ratio differential element of the II buses and the differential compound voltage element of the II buses are triggered, and a bus combined switch and a bus tripping signal are output;
the signal of the I mother differential composite voltage element is triggered or the signal of the II mother differential composite voltage element is triggered, and meanwhile, the signal of the I mother small difference differential current is triggered or the signal of the II mother small difference differential current is triggered, and a tripping signal of the bus combined switch is output.
The invention also provides a bus compound ratio differential protection device, which adopts the bus compound ratio differential protection method, and comprises the following steps:
the data acquisition module is used for acquiring real-time quantity, abrupt change quantity, bus voltage, low voltage, secondary zero sequence voltage and secondary negative sequence voltage of the phase current;
the logic judging module is used for judging whether the signals of the bus small-difference differential current, the bus small-difference compound ratio differential element and the bus differential compound voltage element are all triggered when the bus is in a single bus state;
the device is also used for judging whether signals of the differential current of the small difference of the bus, the differential element of the small difference compound ratio of the bus and the differential compound voltage element of the bus are all triggered when the bus is in a double-bus state, and outputting a bus combined switch and an I bus tripping signal;
the signals of the differential current of the II buses, the differential double ratio differential element of the II buses and the differential composite voltage element of the II buses are triggered or not, and a bus combined switch and a bus tripping signal are output;
the method comprises the steps that whether an I mother differential composite voltage element signal is triggered or whether an II mother differential composite voltage element signal is triggered or not is triggered, and meanwhile, whether an I mother small difference differential current signal is triggered or whether an II mother small difference differential current signal is triggered or not is triggered;
and the signal output module is used for outputting a corresponding bus tripping signal and a corresponding bus combined switch tripping signal according to the judgment result of the logic judgment module.
Further, the real-time phase current amount refers to a phase current acquisition value, and the phase current abrupt amount refers to a phase current acquisition value which is 1.1 times or more of the previous 1 cycle current acquisition value, or a phase current acquisition value which is 0.9 times or less of the previous 1 cycle phase current acquisition value.
Further, the bus voltage is a collection value of the three-phase bus phase voltage.
Further, the low voltage is a phase current acquisition value that acquires 0.9 times or less of the average acquisition value of the first 1 cycle line voltage.
In the invention, the composite voltage refers to the sum of zero sequence voltage, negative sequence voltage and low voltage in fault state. The low voltage is used for distinguishing symmetrical three-phase short circuit faults, the zero sequence voltage is used for distinguishing grounding faults, and the negative sequence voltage is used for distinguishing asymmetrical short circuit faults.
In the invention, the phase current real-time quantity and the phase current abrupt change quantity are phase current acquisition values for acquiring different unit intervals, the phase current real-time quantity refers to the phase current acquisition values, and the phase current abrupt change quantity refers to the phase current acquisition values which are 1.1 times or more than or equal to the first 1 cycle current acquisition values or less than or equal to 0.9 times of the first 1 cycle phase current acquisition values; the bus voltage is a phase voltage acquisition value of the three-phase bus, the low voltage is a phase current acquisition value which is less than or equal to 0.9 times of the average acquisition value of the previous 1 cycle line voltage, and the negative sequence voltage is obtained through bus voltage decomposition.
The large difference criterion is the sum of currents of all lines except the bus-bar circuit breaker and the sectionalized circuit breaker on the bus, the small difference criterion is the sum of currents of all branches including the bus-bar circuit breaker and the sectionalized circuit breaker on the bus, the large difference criterion can distinguish whether the range of the fault is in a zone or out of the zone, the large difference criterion is usually used as a starting element of differential protection, the small difference criterion can judge which bus the fault is particularly on, and the small difference criterion is usually used as a selecting element of bus protection.
Compared with the prior art, the invention has the beneficial effects that: the invention utilizes the ratio characteristics of the reduction of the multi-terminal voltage amplitude of the line and the effective distinction of the current action area and the brake area during normal operation and external short circuit to construct a differential protection method based on current and voltage, can efficiently treat most of fault problems including buses on the premise of not upgrading and reforming the existing distribution network on a large scale, and has the advantages of both protection economy and practicality.
The conventional current differential technology is adopted, the voltage criterion is introduced, the influence of unbalanced current on the differential technology can be reduced, and the line fault selectivity success rate and the protection reliability can be better improved.
Drawings
FIG. 1 is a logic block diagram of a bus compound ratio differential protection method of the present invention;
FIG. 2 is a graph showing the performance characteristics of a multiple ratio differential element;
fig. 3 is a schematic structural diagram of the bus compound ratio differential protection device of the present invention.
Detailed Description
The present invention will be described in further detail with reference to examples.
It will be appreciated by those skilled in the art that the following examples are illustrative of the present invention and should not be construed as limiting the scope of the invention. The specific techniques or conditions are not identified in the examples and are performed according to techniques or conditions described in the literature in this field or according to the product specifications. The materials or equipment used are conventional products available from commercial sources, not identified to the manufacturer.
Example 1: a bus compound ratio differential protection method comprising:
(1) When the bus is in a single bus state, the bus small-difference differential current, the bus small-difference compound ratio differential element and the bus differential compound voltage element take AND logic, and whether the bus trips signals are output;
(2) When the buses are in a double-bus state, taking AND logic of the differential current of the small difference of the I buses, the differential element of the small difference of the I buses and the differential composite voltage element of the I buses, and outputting a bus combined switch and whether the I buses trip signals;
the differential voltage device comprises a differential voltage element, a bus combined switch and a bus tripping signal, wherein the differential voltage element is connected with the bus;
and outputting a tripping signal of the bus combined switch after taking the result of the OR logic of the I and II differential composite voltage elements and taking the result of the OR logic of the I and II differential currents.
Example 2: a bus compound ratio differential protection method comprising:
(1) When the bus is in a single bus state, the bus small-difference differential current, the bus small-difference compound ratio differential element and the bus differential compound voltage element take AND logic, and whether the bus trips signals are output;
(2) When the buses are in a double-bus state, taking AND logic of the differential current of the small difference of the I buses, the differential element of the small difference of the I buses and the differential composite voltage element of the I buses, and outputting a bus combined switch and whether the I buses trip signals;
the differential voltage device comprises a differential voltage element, a bus combined switch and a bus tripping signal, wherein the differential voltage element is connected with the bus;
and outputting a tripping signal of the bus combined switch after taking the result of the OR logic of the I and II differential composite voltage elements and taking the result of the OR logic of the I and II differential currents.
When the phase current abrupt change Id is more than or equal to the phase current abrupt change definite value Id set Triggering a bus small-difference differential current signal; wherein Id set A value of 0.1I sum ~0.15I sum ，I sum The sum of the absolute values of all component phase current fault variation values on the bus.
When the compound ratio is K r Not less than complex ratio fixed value K rset When the bus small differential compound ratio differential element signal is triggeredThe method comprises the steps of carrying out a first treatment on the surface of the Wherein the multiple ratio，I d The amount of operating current for differential protection,I r a brake current amount for differential protection; complex ratio constant value K rset The value is 1.15-1.4.
Triggering a bus differential composite voltage element signal when the bus voltage is lower than or equal to a differential protection low voltage fixed value, or when the secondary zero sequence voltage is greater than or equal to a differential protection zero sequence voltage fixed value, or the secondary negative sequence voltage is greater than or equal to a differential protection negative sequence voltage fixed value;
wherein, the differential protection low voltage constant value takes 65% -70% PU per unit value; the differential protection zero sequence voltage constant value takes 7% -17% PU per unit value; the constant value of the differential protection negative sequence voltage takes 7% -17% of PU per unit value.
When the bus is in a single bus state, the signals of the bus small-difference differential current, the bus small-difference compound ratio differential element and the bus differential compound voltage element are triggered, and a bus tripping signal is output.
When the buses are in a double-bus state, signals of the differential current of the small difference of the I bus, the differential element of the small difference of the I bus and the differential composite voltage element of the I bus are all triggered, and a bus combined switch and an I bus tripping signal are output;
the signals of the differential current of the II buses, the differential compound ratio differential element of the II buses and the differential compound voltage element of the II buses are triggered, and a bus combined switch and a bus tripping signal are output;
the signal of the I mother differential composite voltage element is triggered or the signal of the II mother differential composite voltage element is triggered, and meanwhile, the signal of the I mother small difference differential current is triggered or the signal of the II mother small difference differential current is triggered, and a tripping signal of the bus combined switch is output.
Example 3: compared with the traditional ratio brake criterion, the compound ratio differential criterion of the invention introduces differential current in the calculation of braking quantity, as shown in figure 1, when the bus area fails, the compound ratio differential criterion has extremely strong braking characteristic, and when the bus area fails, the compound ratio differential criterion has no braking, thus the compound ratio differential criterion can more clearly distinguish the out-of-area failure and the in-area failure, and the principle is shown in figure 2.
The current input quantity of each branch in the bus isI i Bus differential current(i.e. the amount of action current for differential protection), bus brake current +.>(i.e. differential protection brake current flow), composite brake currentRatio brake coefficient->. Faults are divided into intra-zone faults and out-of-zone faults, and under the condition of the in-zone faults: />The ratio brake coefficient is equal to infinity.
In the case of an out-of-zone fault: taking into account unbalanced differential current generated by fault branch current transformer errors, which is also differential current in case of out-of-zone faultsI d (i.e. the amount of action current of differential protection), the fault branch short-circuit current isI k The actual braking current (i.e. the differential protection braking current flow) is. Because of the measurement error of the current transformer and the capacitive current and the like of the circuit, the true value of the double braking current is difficult to obtain. The logic method of the bus compound ratio differential protection method of the invention is mainly described according to fig. 1, when the bus is in a single bus state, the bus small difference differential current, the bus small difference compound ratio differential element and the bus differential compound voltage element take AND logic, and a bus tripping signal is output; when the buses are in a double-bus state, the differential current of the small difference of the I bus, the differential element of the small difference of the I bus and the differential composite voltage element of the I bus take AND logic to output a tripping signal of the I bus, the differential current of the small difference of the II bus and the II busThe line small difference compound ratio differential element and the II bus differential compound voltage element take AND logic to output a II bus trip signal, the I bus differential compound voltage element and the II bus differential compound voltage element take OR logic results, then sum, the I bus small difference differential current and the II bus small difference differential current take OR logic results, and the AND logic results are taken to output a bus combined switch trip signal. The busbar small differential current, the busbar small differential double ratio differential element, and the busbar differential double voltage element control protection method are described in detail below.
A. Small differential current case: phase current abrupt amount is Id; the sum of the absolute values of the phase current fault variation of all the elements on the bus is I sum . The phase current suddenly changes to a fixed value, and enough sensitivity is ensured when the bus minimum mode fails. General Id set A value of 0.1I sum ~0.15I sum . When Id is greater than or equal to Id set When this signal is triggered.
B. Small differential compound ratio differential case: the bus does not flow back to the bus when the bus fails, but flows into the ground, namely the action current amount of differential protectionI d The method comprises the steps of carrying out a first treatment on the surface of the The sum of absolute values of inflow and outflow amounts of normal bus bars is used as the braking current amount of differential protectionI r Duplex ratioWhen K is r ≥K rset When the signal is triggered; k (K) rset Is a complex ratio fixed value, a complex ratio fixed value K rset The value is 1.15-1.4.
Complex ratio fixed upper limit value: when the CT error limit is 10P, i.e. the CT composite error is not more than 10%, K rset 1.2; when CT error has saturated severely and exceeds the error limit requirement, 20% error is allowed, K is rset 1.3; exceeding the error limit requirement, when 40% error deviation is allowed, K rset 1.4; when the deviation is greater than 40% of the error limit, K rset The maximum value is 1.4. When the CT error limit is 5P, that is, the CT composite error is not more than 10%, K rset 1.15; when CT error has become severely saturated, the error is exceededLimit requirement, when 20% error deviation is allowed, K rset 1.25; exceeding the error limit requirement, when 40% error deviation is allowed, K rset 1.35; when the deviation is greater than 40% of the error limit, K rset The maximum value is 1.35.
Complex ratio fixed value lower limit value: when the CT error limit is 10P, i.e. the CT composite error is not more than 10%, K rset 1.2, at this time K rset The value is the minimum value of 1.2; when the CT error limit is 5P, that is, the CT composite error is not more than 5%, K rset 1.15, at this time K rset The value is the minimum value of 1.15.
C. Differential composite voltage element case: 1) The differential protection low voltage fixed value (line voltage) is mainly aimed at the characteristic of voltage reduction when the bus is short-circuited, the bus voltage acts under the lowest operation voltage of the bus, and the bus can reliably return under the lowest operation voltage of the bus after the fault is removed. The constant value of the differential protection low voltage is generally 65% -70% PU per unit value. Assuming that the bus voltage is U, the per unit value is U PU Differential protection low voltage constant value (line voltage) is U set ，U set =（0.65-0.7）U PU According to parameters U such as wire diameter, wiring mode, length and the like of the primary and secondary conducting wire materials of the actual bus set Flexibly arranged in 0.65-0.70, U PU ≤U set When the voltage element acts, U after fault removal PU ＞U set Reliably returns.
2) The differential protection zero-sequence voltage fixed value (zero-sequence value synthesized by three-phase voltage vectors) mainly aims at the characteristic that the zero-sequence voltage becomes large when a bus is grounded, and avoids the zero-sequence component of the maximum unbalanced voltage when the bus normally operates. The secondary zero sequence voltage generally takes (4-8) V. The PU per unit value is generally taken (7% -14%). Let the zero sequence voltage be U 0 The per unit value is U 0PU Differential protection zero sequence low voltage constant value (zero sequence) is U 0set ，U 0set =（0.07-0.14）U 0PU According to parameters U such as wire diameter, wiring mode, length and the like of the primary and secondary conducting wire materials of the actual bus 0set Flexibly arranged in 0.07-0.14, U 0PU ≥U 0set When the voltage element is operated,u after fault removal 0PU <U 0set Reliably returns.
3) The differential protection negative sequence voltage fixed value (the negative sequence value synthesized by three-phase voltage vectors) mainly aims at the characteristics of the conditions of unbalanced three-phase load, open phase and the like of a bus and avoids the negative sequence component of the maximum unbalanced voltage when the bus normally operates. The secondary negative sequence voltage is generally (2-6) V. The PU per unit value is generally taken as (4% -11%). Assume that the negative sequence voltage is U - The per unit value is U -PU Differential protection negative sequence low voltage constant value U -set ，U -set =（0.04-0.11）U -PU According to parameters U such as wire diameter, wiring mode, length and the like of the primary and secondary conducting wire materials of the actual bus -set Flexibly set in 0.04-0.11, U -PU ≥U -set When the voltage element acts, U after fault removal -PU <U -set Reliably returns.
It will be apparent to those skilled in the art that the protection control logic of the present invention described above may be implemented in a general purpose computing device, they may be centralized on a single computing device, or distributed over a network of computing devices, or they may alternatively be implemented in existing program code or algorithms executable by the computing device, such that they are stored in a memory device and executed by the computing device, or they may be separately fabricated into individual integrated circuit modules, or multiple modules or steps within them may be fabricated into a single integrated circuit module. Thus, the functional implementation of the present invention is not limited to any specific combination of hardware and software.
As shown in fig. 3, a bus double ratio differential protection device, which adopts the bus double ratio differential protection method, comprises:
the data acquisition module 101 is used for acquiring real-time quantity, abrupt change quantity, bus voltage, low voltage, secondary zero sequence voltage and secondary negative sequence voltage of phase current;
the logic judging module 102 is used for judging whether the signals of the bus small-difference differential current, the bus small-difference compound ratio differential element and the bus differential compound voltage element are all triggered when the bus is in a single bus state;
the device is also used for judging whether signals of the differential current of the small difference of the bus, the differential element of the small difference compound ratio of the bus and the differential compound voltage element of the bus are all triggered when the bus is in a double-bus state, and outputting a bus combined switch and an I bus tripping signal;
the signals of the differential current of the II buses, the differential double ratio differential element of the II buses and the differential composite voltage element of the II buses are triggered or not, and a bus combined switch and a bus tripping signal are output;
the method comprises the steps that whether an I mother differential composite voltage element signal is triggered or whether an II mother differential composite voltage element signal is triggered or not is triggered, and meanwhile, whether an I mother small difference differential current signal is triggered or whether an II mother small difference differential current signal is triggered or not is triggered;
and the signal output module 103 is used for outputting whether the corresponding bus is tripped or not and whether the bus combined switch is tripped or not according to the judgment result of the logic judgment module.
The bus duplex ratio differential protection device provided by the embodiment of the invention utilizes the ratio characteristics of reduced voltage amplitude of the line multi-terminal and effective distinction between the current action area and the braking area during normal operation and external short circuit, introduces voltage criteria, can efficiently treat most of faults containing buses on the premise of not upgrading and reforming the existing distribution network on a large scale, and has the advantages of both protection economy and practicality.
The apparatus provided in the embodiments of the present invention is used to execute the above embodiments of the method, and specific flow and details refer to the above embodiments, which are not repeated herein.
The foregoing has shown and described the basic principles, principal features and advantages of the invention. It will be understood by those skilled in the art that the present invention is not limited to the embodiments described above, and that the above embodiments and descriptions are merely illustrative of the principles of the present invention, and various changes and modifications may be made without departing from the spirit and scope of the invention, which is defined in the appended claims. The scope of the invention is defined by the appended claims and equivalents thereof.
Claims (10)
1. A bus compound ratio differential protection method, comprising:
(1) When the bus is in a single bus state, the bus small-difference differential current, the bus small-difference compound ratio differential element and the bus differential compound voltage element take AND logic, and whether the bus trips signals are output;
(2) When the buses are in a double-bus state, taking AND logic of the differential current of the small difference of the I buses, the differential element of the small difference of the I buses and the differential composite voltage element of the I buses, and outputting a bus combined switch and whether the I buses trip signals;
the differential voltage device comprises a differential voltage element, a bus combined switch and a bus tripping signal, wherein the differential voltage element is connected with the bus;
and outputting a tripping signal of the bus combined switch after taking the result of the OR logic of the I and II differential composite voltage elements and taking the result of the OR logic of the I and II differential currents.
2. The bus bar double ratio differential protection method according to claim 1, wherein when the phase current abrupt amount Id is equal to or larger than the phase current abrupt fixed value Id set Triggering a bus small-difference differential current signal; wherein Id set A value of 0.1I sum ~0.15I sum ，I sum The sum of the absolute values of all component phase current fault variation values on the bus.
3. The bus bar multiple ratio differential protection method according to claim 1, wherein when the multiple ratio K r Not less than complex ratio fixed value K rset Triggering a busbar small-difference compound ratio differential element signal; wherein the multiple ratio，I d The amount of operating current for differential protection,I r brake current flow for differential protectionThe method comprises the steps of carrying out a first treatment on the surface of the Complex ratio constant value K rset The value is 1.15-1.4.
4. The bus double ratio differential protection method according to claim 1, wherein when the bus voltage is lower than or equal to the differential protection low voltage fixed value, or when the secondary zero sequence voltage is greater than or equal to the differential protection zero sequence voltage fixed value, or the secondary negative sequence voltage is greater than or equal to the differential protection negative sequence voltage fixed value, triggering the bus differential composite voltage element signal;
wherein, the differential protection low voltage constant value takes 65% -70% PU per unit value; the differential protection zero sequence voltage constant value takes 7% -17% PU per unit value; the constant value of the differential protection negative sequence voltage takes 7% -17% of PU per unit value.
5. The bus bar double ratio differential protection method according to claim 1, wherein when the bus bar is in a single bus bar state, the bus bar small difference differential current, the bus bar small difference double ratio differential element, and the bus bar differential double voltage element signals are all triggered, and a bus bar trip signal is output.
6. The bus double ratio differential protection method according to claim 1, wherein when the bus is in a double bus state, the signals of the I bus small difference differential current, the I bus small difference double ratio differential element and the I bus differential double voltage element are all triggered, and a bus combined switch and an I bus trip signal are output;
the signals of the differential current of the II buses, the differential compound ratio differential element of the II buses and the differential compound voltage element of the II buses are triggered, and a bus combined switch and a bus tripping signal are output;
the signal of the I mother differential composite voltage element is triggered or the signal of the II mother differential composite voltage element is triggered, and meanwhile, the signal of the I mother small difference differential current is triggered or the signal of the II mother small difference differential current is triggered, and a tripping signal of the bus combined switch is output.
7. A bus compound ratio differential protection device employing the bus compound ratio differential protection method according to any one of claims 1 to 6, comprising:
the data acquisition module is used for acquiring phase current real-time quantity, phase current abrupt quantity, bus voltage, low voltage, secondary zero sequence voltage and secondary negative sequence voltage;
the logic judging module is used for judging whether the signals of the bus small-difference differential current, the bus small-difference compound ratio differential element and the bus differential compound voltage element are all triggered when the bus is in a single bus state;
the device is also used for judging whether signals of the differential current of the small difference of the bus, the differential element of the small difference compound ratio of the bus and the differential compound voltage element of the bus are all triggered when the bus is in a double-bus state, and outputting a bus combined switch and an I bus tripping signal;
the signals of the differential current of the II buses, the differential double ratio differential element of the II buses and the differential composite voltage element of the II buses are triggered or not, and a bus combined switch and a bus tripping signal are output;
the method comprises the steps that whether an I mother differential composite voltage element signal is triggered or whether an II mother differential composite voltage element signal is triggered or not is triggered, and meanwhile, whether an I mother small difference differential current signal is triggered or whether an II mother small difference differential current signal is triggered or not is triggered;
and the signal output module is used for outputting a corresponding bus tripping signal and a corresponding bus combined switch tripping signal according to the judgment result of the logic judgment module.
8. The busbar double ratio differential protection device according to claim 7, wherein the phase current real-time quantity refers to a phase current collection value, and the phase current abrupt quantity refers to a phase current collection value that is 1.1 times or more of the previous 1 cycle current collection value, or a phase current collection value that is 0.9 times or less of the previous 1 cycle phase current collection value.
9. The busbar double ratio differential protection device according to claim 7, wherein the busbar voltage is an acquisition value of the busbar phase voltage of three phases.
10. The busbar double ratio differential protection device according to claim 7, wherein the low voltage is a phase current acquisition value that acquires 0.9 times or less of an average acquisition value of the first 1 cycle line voltage.
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