CN115902511A - Active power distribution network fault positioning system and method based on passive protection - Google Patents
Active power distribution network fault positioning system and method based on passive protection Download PDFInfo
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Abstract
The invention relates to an active power distribution network fault positioning system based on passive protection and a method thereof. The method comprises the following steps: according to a control strategy of a distributed power grid-connected inverter, a controlled current source model is established to obtain a distributed power grid-connected point impedance branch model; establishing an active distribution network sequence component calculation network to calculate branch current of a distribution network feeder line; the passive protection terminal collects current of a feeder line of the power distribution network, and the uPMU synchronous measurement terminal collects voltage measurement data and transmits the data to the fault positioning host for matching so as to search the position of a fault point and isolate a fault section. Compared with the prior art, the method can accurately position the fault and improve the power supply reliability of the power distribution network.
Description
Technical Field
The invention relates to the technical field of power distribution network protection, in particular to an active power distribution network fault positioning system and method based on passive protection.
Background
The traditional power Distribution network is a unidirectional power flow network, but after Distributed Energy Resources (DER) such as Distributed Generation (DG), electric vehicles and controllable loads are accessed, the traditional power Distribution network faces many new challenges which never occur, the network structure and the power flow direction are necessarily affected by the access of DG, the traditional power Distribution network becomes a complex network with multiple power supplies, and as the permeability of DG is continuously improved, the fault characteristics of the power Distribution network are changed under the influence of the distributed power supplies and the DG control strategy thereof, and the protection reliability of the power Distribution network is affected.
After the new energy is connected to the power distribution network in a high proportion, the fault current is influenced by a control strategy of the distributed power supply, and the passive protection action sensitivity and the protection coordination which are arranged on the ring main unit have problems; and the fault current direction may be two-way, and the ring main unit passive protection terminal does not measure the line voltage, can not judge the direction of the fault point, can not reliably identify the fault point position.
The rapid positioning, isolation and recovery of the fault after the fault occurs in the power distribution network are important for improving the reliability of the power distribution network and ensuring the normal operation of economic and social activities and the life of residents. Modern active power distribution network structure is complicated, and numerous and distributed power source of branch circuit inserts widely, leads to the location of circuit fault section to be more difficult, relies mainly on distribution network automation equipment such as feeder terminal unit, intelligent terminal unit to carry out the fault location now, but only is applicable to the distribution network that DG permeability is less than 25%.
The traveling wave method widely applied to the power transmission line with a relatively simple structure determines the position of a fault point by measuring the propagation time of voltage and current traveling waves between the fault point and a bus, but the high requirements on time synchronization rate and sampling rate limit the application range of the traveling wave method, the traveling wave method is difficult to adapt to a power distribution network, and the traveling wave method lacks universality for complex fault situations such as double faults and faults above.
Disclosure of Invention
The invention aims to overcome the defects in the prior art and provide an active power distribution network fault positioning system based on passive protection and a method thereof.
The purpose of the invention can be realized by the following technical scheme: an active power distribution network fault positioning system based on passive protection comprises passive protection terminals installed on an active power distribution network switch cabinet and a ring main unit, and uPMU installed on a distributed power supply access point and a voltage bus of a distribution network system, wherein the passive protection terminals and the uPMU are respectively connected with a fault positioning host computer, the fault positioning host computer is connected with a distribution network dispatching automation system, and the passive protection terminals are used for collecting feeder line current of a power distribution network and transmitting the feeder line current to the fault positioning host computer;
the uMPU is used for collecting voltage measurement data and transmitting the voltage measurement data to the fault positioning host;
the fault positioning host searches and determines the position of a fault point according to the current and voltage measurement data of a feeder line of the power distribution network and by combining remote signaling and remote measuring information of a distribution network dispatching automation system based on an adaptive protection setting calculation model, and outputs a corresponding control instruction to the passive protection terminal so as to control the on and off of each switch in the passive protection terminal.
An active power distribution network fault positioning method based on passive protection comprises the following steps:
s1, establishing a controlled current source model according to a grid-connected inverter control strategy of the distributed power supply to obtain a grid-connected point impedance branch model of the distributed power supply;
s2, establishing an active distribution network sequence component calculation network for calculating branch current of a distribution network feeder line;
and S3, the passive protection terminal collects the current of the feeder line of the power distribution network, and the uPMU synchronous measurement terminal collects voltage measurement data, and the voltage measurement data are transmitted to the fault positioning host through communication to be matched so as to search the position of a fault point and isolate a fault section.
Further, the step S1 specifically includes the following steps:
s11, determining the output characteristics of an inverter according to a control strategy of a distributed power supply grid-connected inverter;
s12, deriving a relation between modulation voltage and current based on a grid-connected inverter control system structure, and establishing a voltage-current equation of a grid-connected point of the new energy power supply;
and S13, establishing a relation between the DG fault output and a control strategy, output power, a reactive support coefficient and grid-connected point voltage on the basis of the relation between the fault output and the grid-connected point.
Further, the inverter output characteristic in step S11 is specifically:
wherein, I * 、
Are fault conditions, respectivelyThe DG fault output current, the d-axis and q-axis components of the fault current are fed down, K is a reactive support coefficient, and U is a reactive support coefficient PCC To the grid-connected point voltage, P ref Is referred to as active power output.
Further, the specific process of step S12 is:
the inverter realizes the control of the control system on the current by regulating the terminal voltage, and the modulation voltage and the current satisfy the following relation:
wherein, V * The voltage of the output end of the inverter is k, the adjustment coefficient of the PI controller is k, and i and u are the voltage and the current value of a measuring point;
from the ac side, a relationship between the inverter terminal voltage and the equivalent resistance R, L inductance between the measurement points is established:
in practical cases, the PWM carrier frequency is as high as several kilohertz, and the inverter terminal voltage is equivalent to the modulation voltage, thereby establishing the current relationship between the control side and the ac side, and the formula is as follows:
further, the specific process of step S13 is:
knowing the relation between the fault output and the grid-connected point after the fault occurs, the inverter output current is brought into the relation between the control side current and the alternating current side current, and the relation between the DG fault output and the control strategy, the output power, the reactive support coefficient and the grid-connected point voltage is obtained, and the relation is specifically as follows:
wherein i f The fault is a force.
Further, the specific process of step S2 is:
according to different types of distributed power supplies and different control strategies, a node voltage equation is established, and a voltage source branch circuit is converted into a current source branch circuit, wherein the node voltage equation specifically comprises the following steps:
Y B ＝(y 1 ...y n ) T
the node admittance matrix thus formed is:
Y＝AY B A T
the node voltage equation and the branch current equation are as follows:
wherein, the first and the second end of the pipe are connected with each other,
is a branch voltage, formed by the node voltage.
Further, the step S3 of searching for the location of the fault point specifically includes the following steps:
s31, modifying the admittance matrix in the fault searching process;
and S32, matching the fault current and determining the position of the fault point.
Further, the specific process of step S31 is:
assuming that the original power system has N independent nodes, when the system operates normally, the node admittance matrix can be expressed as:
when a power system fails, a node is added to an original network, Y' is (N + 1) order, and specifically:
after a new node f is added, compared with Y, Y' only changes admittance among fault nodes, namely only changes self-admittance and mutual admittance of nodes i, j and f, but diagonal elements are still equal, and faults are divided into ground faults and interphase faults;
if the grounding short circuit occurs, a new node is added between the nodes i and j, and a new grounding branch is added at the same time, specifically:
Y' ii ＝(Y ii -Y fj )
Y if ＝Y fj
Y ij '＝Y ji '＝0
Y jj '＝(Y jj -Y if )
ΔY ff ＝Y ff -|Y if +Y fj |
wherein, delta Y ff The fault point grounding admittance under the condition of the non-metallic grounding fault;
if the fault is an inter-phase short circuit, a new node and a non-grounded branch Y 'are added between the nodes i and j' ii 、Y ij '、Y jj '、Y if The variation is the same as the ground fault, and the node admittance matrix varies as follows:
Y ff ＝|Y if +Y fj |。
further, the step S32 is specifically to match the fault current collection value in combination with a fault current search formula of the active power distribution network, and if the fault current search value and the current value collected by the passive protection terminal satisfy the matching formula, it is determined that the fault current is completely matched, and a corresponding fault point positioning result is output.
Further, the active power distribution network fault current search formula is as follows:
where k is the branch number of the search, d k The distance between the fault point and the head end of the line is searched according to the set step length and the change of the distance length,
for positive sequence voltages acquired by n uPMUs in the power grid, the voltage value is greater than or equal to>
Is the system negative sequence voltage;
the matching formula is specifically as follows:
wherein, the first and the second end of the pipe are connected with each other,
when the matching formula is established, the fault current is completely matched, and a fault branch and a fault position d are output k The value is obtained.
Compared with the prior art, the invention has the following advantages:
1. the fault location accuracy is high, and the current matching fault location method which integrates multi-source data and establishes an admittance equation calculation mathematical model is adopted by taking the active power distribution network as a research object, so that the position of a fault point can be reliably identified, and a fault line can be quickly isolated. According to the method, a controlled current source model is established according to a control strategy of a distributed power supply, and a sequence component network model of a distribution network is established for calculating branch current of a distribution network feeder line; the synchronous voltage accessed by the distributed power supply access point and the distribution network system is collected to be used as excitation voltage, the feeder branch current is calculated, and the excitation voltage is matched with the terminal collection current of the passive protection of the ring main unit, so that the position of a fault point is searched, and a fault section is isolated. The fault section can be reliably and accurately positioned under the short-circuit fault or the broken line fault, is not influenced by the fault type and the fault position, and has better transition resistance capability, so that the fault positioning accuracy is high.
2. The looped network cabinet passive protection terminal is arranged on the active power distribution network switch cabinet and the looped network cabinet, is used for collecting the current of a power distribution network feeder line, calculates the real part and the imaginary part of the current and transmits the current to the fault positioning host through communication; the method installs the uPMU synchronous measurement terminal at an access point of the distributed power supply so as to transmit the real part and the imaginary part of the voltage measurement data marked with the time scales to the fault positioning host. The passive protection terminal does not need synchronous measurement, and the voltage of the distributed power supply access point is synchronously measured through the uPMU. In order to ensure that the fault can be quickly detected after the fault occurs, current and voltage data are uploaded according to a set time interval, a tripping command is sent out after the fault is detected, a feeder line is directly disconnected through a passive protection terminal, and the fault line is isolated. The active power distribution network self-adaptive protection setting calculation model fusing the ring main unit passive protection data and the uPMU measurement data can provide a better measurement data base for fault positioning, and has important significance for realizing rapid and accurate fault positioning of the power distribution network and improving the power supply reliability of the power distribution network, so that the protection reliability is high.
Drawings
FIG. 1 is a schematic diagram of the system of the present invention;
FIG. 2 is a schematic flow diagram of the process of the present invention;
FIG. 3 is a control system structure of the grid-connected inverter in the embodiment;
FIG. 4 is an active power distribution network model provided in an embodiment;
FIG. 5 is a diagram of a model wiring of an active distribution network provided in an embodiment;
FIG. 6 is a positive sequence computing network of an active distribution network model provided in an embodiment;
fig. 7 is a negative sequence computing network of an active distribution network model provided in an embodiment.
Detailed Description
The invention is described in detail below with reference to the figures and specific embodiments.
Examples
As shown in fig. 1, an active power distribution network fault location system based on passive protection comprises passive protection terminals installed on an active power distribution network switch cabinet and a ring main unit, and a uPMU installed on a distributed power supply access point and a voltage bus of a distribution network system, wherein the passive protection terminals and the uPMU are respectively connected with a fault location host, the fault location host is connected with a distribution network dispatching automation system, and the passive protection terminals are used for collecting feeder line current of a power distribution network and transmitting the feeder line current to the fault location host;
the uMPU is used for collecting voltage measurement data and transmitting the voltage measurement data to the fault positioning host;
and the fault positioning host searches and determines the position of a fault point based on a self-adaptive protection setting calculation model according to the current and voltage measurement data of a feeder line of the power distribution network and by combining remote signaling and telemetering information of a distribution network dispatching automation system, and outputs a corresponding control instruction to the passive protection terminal so as to control the on-off of each switch in the passive protection terminal.
By applying the system, the active power distribution network fault positioning method based on passive protection is realized, as shown in fig. 2, and comprises the following steps:
s1, establishing a controlled current source model according to a grid-connected inverter control strategy of the distributed power supply to obtain a grid-connected point impedance branch model of the distributed power supply;
s2, establishing an active distribution network sequence component calculation network for calculating branch current of a distribution network feeder line;
and S3, the passive protection terminal collects the current of the feeder line of the power distribution network, the uPMU synchronous measurement terminal collects voltage measurement data, and the voltage measurement data are transmitted to the fault positioning host through communication to be matched so as to search the position of a fault point and isolate a fault section.
Aiming at the problem of low accuracy of fault location of the current active power distribution network, the technical scheme considers that the micro phasor measurement unit (uPMU) can obtain high-precision phase information along with the application of the uPMU in the power distribution network, so that conditions can be provided for fault location of the power distribution network based on online parameter identification; in addition, the traditional protection does not form a self-adaptive protection system and is not considered to be applied to a distribution network containing a large number of ring main units. Therefore, the technical scheme utilizes the passive overcurrent protection with the protection function and the data communication function as a distribution network protection terminal, combines with the existing adaptive protection research result, and cooperates with the uPMU phasor information to construct an active distribution network adaptive protection setting calculation model fusing the looped network cabinet passive protection data and the uPMU measurement data, thereby having important significance for improving the performance of the active distribution network protection system.
The embodiment applies the above technical solution, and mainly includes the following contents:
1. and establishing a controlled current source model through a grid-connected inverter control strategy of the distributed power supply to obtain a grid-connected point impedance branch model of the distributed power supply.
When the voltage of the grid-connected point is greater than 0.95pu, the control strategy of the inverter is unchanged; when the grid-connected operation voltage is less than the minimum grid-connected operation voltage, the DG outputs reactive current iq only inverted, and 1.2I is taken under the normal condition N . In this interval, the inverter output current Ipcc is:
in the formula I * 、
Respectively representing DG fault output current, d-axis and q-axis components of the fault current under the fault condition; k is the reactive support coefficient and is usually 2,U PCC To grid point voltage, P ref Is a reference active power output.
The structure of the grid-connected inverter control system is shown in fig. 3, and the inverter realizes the control of the control system on current by regulating terminal voltage. The modulation voltage and the current satisfy the following relation:
in the formula, V * And k is the voltage of the output end of the inverter, k is the regulating coefficient of the PI controller, and i and u are the voltage and the current value of the measuring point.
From the alternating current side, the relation between the voltage of the inverter terminal and the inductance of the equivalent resistance R, L between the measurement points is established, and the relation is specifically expressed as:
in practical cases, where the PWM carrier frequency is as high as several kilohertz, the inverter terminal voltage can be considered equivalent to the modulation voltage, thereby establishing the control-side to ac-side current relationship:
knowing the relationship between the fault output and the grid-connected point after the fault occurs, the inverter output current is brought into the relationship between the control side current and the alternating current side current, and the relationship between the DG fault output and the control strategy, the output power, the reactive support coefficient and the grid-connected point voltage can be obtained, specifically as follows:
2. establishing an active distribution network sequence component calculation network for calculating branch current of a distribution network feeder line
According to the relationship between DG fault output and a control strategy, output power, a reactive support coefficient and grid-connected point voltage, a node voltage equation of the distributed power supply can be equivalent to a voltage-controlled current source, and the current value of the voltage-controlled current source can be obtained by solving a differential equation by taking the voltage of an access point as an excitation quantity. Because the load current is small and can be ignored compared with the short-circuit current, the power distribution network can be considered to be in no load, and the voltage of a power grid system connected to the power distribution network is known. Therefore, the solution to the distribution network fault current becomes: under the condition of no load, an equivalent current source and a power grid voltage source of the distributed power supply are used as excitation quantities, and the line current of the distribution network containing the fault point is used as a response calculation model.
In order to obtain the access point voltage of the distributed power supply and the voltage of the distribution network system, a synchronous measurement unit (pmu) is respectively installed on a distributed power supply access point and a voltage bus of the distribution network system, so as to obtain the synchronous measurement voltage of the whole distribution network and obtain the excitation quantity of a fault current calculation model, wherein a specific active distribution network model is shown in fig. 4.
If the active power distribution network online calculation model analyzes short-circuit faults according to a three-phase system, if the short-circuit faults are n branches, the admittance matrix is 3n × 3n, and the calculation amount is large. If the calculation network is decomposed into a sequence network, the sequence admittance matrix is changed into n x n, and the calculation amount is reduced.
Due to the difference in fault times during fault ride-through, the control strategy of the distributed power supply plays a different role. According to different types of distributed power supplies and different control strategies, the voltage source branch is converted into the current source branch due to the fact that a node voltage equation is established. The method specifically comprises the following steps:
Y B ＝(y 1 ...y n ) T
in the formula (I), the compound is shown in the specification,
the formed node admittance matrix is as follows:
Y＝AY B A T
the node voltage equation and the branch current equation are as follows:
in the formula (I), the compound is shown in the specification,
is the branch voltage, formed by the node voltage.
Due to the inhibiting effect of the distributed power supply control strategy on the negative sequence current, when asymmetric faults occur, no negative sequence component is output, and the influence of the distributed power supply negative sequence current on a calculation model is ignored. The system wiring diagram, positive sequence wiring and negative sequence wiring are respectively shown in fig. 5, 6 and 7.
3. Searching fault point position, searching and calculating fault current of isolated fault section
When the admittance matrix is modified in the fault searching process, the node admittance matrix can be expressed as follows when the original power system is assumed to have N independent nodes and operates normally:
when a power system fails, a node is added to the original network, and Y' is (N + 1) order.
After adding a new node f, Y' is compared to Y, and only the admittance between the failed nodes changes. That is, only the self-admittance and the mutual admittance of the nodes i, j and f are changed, but the diagonal elements are still equal. Faults can be divided into ground faults and phase-to-phase faults.
When a grounding short circuit occurs, a new node is added between the nodes i and j, and a new grounding branch is added at the same time, specifically:
Y' ii ＝(Y ii -Y fj )
Y if ＝Y fj
Y ij '＝Y ji '＝0
Y jj '＝(Y jj -Y if )
ΔY ff ＝Y ff -|Y if +Y fj |
ΔY ff the fault point grounding admittance under the condition of non-metallic grounding fault.
When the fault is interphase short circuit, a new node is added between the nodes i and j, and the branch circuit is not grounded. Y' ii 、Y ij '、Y jj '、Y if The variation is the same as the ground fault, and the node admittance matrix varies as follows:
Y ff ＝|Y if +Y fj |
because the electrical quantity of the fault node can not be directly obtained, Y of Y' needs to be removed from the actual corresponding node admittance matrix ff The rows and columns of the array.
In addition, matching of the current is calculated through the actual collected current and the model so as to determine the position of a fault point in the active distribution network. The active power distribution network fault current search formula is as follows:
where k is the branch number of the search, d k The distance between the fault point and the head end of the line is searched according to the set step length and the change of the distance length,
for positive sequence voltages acquired by n uPMUs in the power grid, the voltage value is greater than or equal to>
Is the system negative sequence voltage.
When the following formula is satisfied, the fault current is considered to be completely matched, and a fault branch and a fault position d are output k Values, which are specifically expressed as:
in the formula (I), the compound is shown in the specification,
the fault current acquisition value in the active distribution network is obtained.
In summary, according to the technical scheme, the passive protection data and the uPMU measurement data of the ring main unit are fused to perform active power distribution network fault location, firstly, a controlled current source model is established through a grid-connected inverter control strategy of the distributed power supply, and a grid-connected point impedance branch model of the distributed power supply is obtained; then, establishing an active distribution network sequence component calculation network for calculating branch current of a distribution network feeder line; and then the passive protection terminal of the ring main unit collects current of a feeder line of the power distribution network, and the uPMU synchronous measurement terminal collects voltage measurement data, and the voltage measurement data are transmitted to the fault positioning host computer for matching through communication, so that the position of a fault point is searched, and a fault section is isolated. The technical scheme can effectively improve the fault positioning accuracy and the protection reliability of the active power distribution network.
Claims (10)
1. An active power distribution network fault positioning system based on passive protection is characterized by comprising passive protection terminals installed on an active power distribution network switch cabinet and a ring main unit, and uPMUs installed on a distributed power supply access point and a voltage bus of a distribution network system, wherein the passive protection terminals and the uPMUs are respectively connected with a fault positioning host computer, the fault positioning host computer is connected with a distribution network dispatching automation system, and the passive protection terminals are used for collecting feeder line current of a power distribution network and transmitting the feeder line current to the fault positioning host computer;
the uMPU is used for collecting voltage measurement data and transmitting the voltage measurement data to the fault positioning host;
the fault positioning host searches and determines the position of a fault point according to the current and voltage measurement data of a feeder line of the power distribution network and by combining remote signaling and remote measuring information of a distribution network dispatching automation system based on an adaptive protection setting calculation model, and outputs a corresponding control instruction to the passive protection terminal so as to control the on and off of each switch in the passive protection terminal.
2. An active power distribution network fault positioning method based on passive protection is characterized by comprising the following steps:
s1, establishing a controlled current source model according to a grid-connected inverter control strategy of the distributed power supply to obtain a grid-connected point impedance branch model of the distributed power supply;
s2, establishing an active distribution network sequence component calculation network for calculating branch current of a distribution network feeder line;
and S3, the passive protection terminal collects the current of the feeder line of the power distribution network, the uPMU synchronous measurement terminal collects voltage measurement data, and the voltage measurement data are transmitted to the fault positioning host through communication to be matched so as to search the position of a fault point and isolate a fault section.
3. The active power distribution network fault location method based on passive protection as claimed in claim 2, wherein the step S1 specifically includes the steps of:
s11, determining the output characteristics of an inverter according to a control strategy of a distributed power supply grid-connected inverter;
s12, deriving a relation between modulation voltage and current based on a grid-connected inverter control system structure, and establishing a voltage-current equation of a grid-connected point of the new energy power supply;
and S13, establishing a relation between DG fault output and a control strategy, output power, a reactive power support coefficient and grid-connected point voltage on the basis of the relation between the fault output and the grid-connected point.
4. The active power distribution network fault location method based on passive protection as claimed in claim 3, wherein the inverter output characteristics in step S11 are specifically:
wherein, I * 、
Respectively DG fault output current, d-axis and q-axis components of fault current under the condition of fault, K is a reactive support coefficient, and U is a reactive support coefficient PCC To the grid-connected point voltage, P ref Is a reference active power output.
5. The active power distribution network fault location method based on passive protection as claimed in claim 4, wherein the specific process of step S12 is as follows:
the inverter realizes the control of the control system to the current by regulating the terminal voltage, and the modulation voltage and the current satisfy the following relation:
wherein, V * For the output voltage of the inverter, k is the regulating coefficient of the PI controllerI and u are voltage and current values of the measuring points;
from the ac side, a relationship between the inverter terminal voltage and the equivalent resistance R, L inductance between the measurement points is established:
in practical cases, the PWM carrier frequency is as high as several kilohertz, and the inverter terminal voltage is equivalent to the modulation voltage, thereby establishing the current relationship between the control side and the ac side, and the formula is as follows:
6. the active power distribution network fault location method based on passive protection as claimed in claim 5, wherein the specific process of step S13 is as follows:
knowing the relation between the fault output and the grid-connected point after the fault occurs, the inverter output current is brought into the relation between the control side current and the alternating current side current, and the relation between the DG fault output and the control strategy, the output power, the reactive support coefficient and the grid-connected point voltage is obtained, and the relation is specifically as follows:
wherein i f The fault is a force.
7. The active power distribution network fault location method based on passive protection as claimed in claim 6, wherein the specific process of step S2 is:
according to different types of distributed power supplies and different control strategies, a node voltage equation is established, and a voltage source branch circuit is converted into a current source branch circuit, wherein the node voltage equation specifically comprises the following steps:
Y B ＝(y 1 ...y n ) T
the node admittance matrix thus formed is:
Y＝AY B A T
the node voltage equation and the branch current equation are as follows:
wherein the content of the first and second substances,
is a branch voltage, formed by the node voltage.
8. The method according to claim 7, wherein the step of searching for the location of the fault point in the step S3 specifically comprises the steps of:
s31, modifying the admittance matrix in the fault searching process;
and S32, matching the fault current and determining the position of the fault point.
9. The method for positioning the fault of the active power distribution network based on the passive protection as claimed in claim 8, wherein the specific process of the step S31 is as follows:
assuming that the original power system has N independent nodes, when the system operates normally, the node admittance matrix can be expressed as:
when a power system fails, a node is added to an original network, and Y' is (N + 1) order, specifically:
after a new node f is added, compared with Y, Y' only changes admittance among fault nodes, namely only changes self-admittance and mutual admittance of nodes i, j and f, but diagonal elements are still equal, and faults are divided into ground faults and interphase faults;
if a grounding short circuit occurs, a new node is added between the nodes i and j, and a new grounding branch is added at the same time, specifically:
Y' ii ＝(Y ii -Y fj )
Y if ＝Y fj
Y ij '＝Y ji '＝0
Y jj '＝(Y jj -Y if )
ΔY ff ＝Y ff -|Y if +Y fj |
wherein, delta Y ff The fault point grounding admittance under the condition of non-metallic grounding fault;
if the fault is an inter-phase short circuit, a new node and a non-grounded branch are added between the nodes i and j' ii 、Y ij '、Y jj '、Y if The variation is the same as the ground fault, and the node admittance matrix varies as follows:
Y ff ＝|Y if +Y fj |。
10. the active power distribution network fault location method based on passive protection as claimed in claim 9, wherein said step S32 is specifically to match the fault current collection value in combination with the active power distribution network fault current search formula, and if the fault current search value and the current value collected by the passive protection terminal satisfy the matching formula, the fault current is considered to be completely matched, and a corresponding fault point location result is output;
the active power distribution network fault current search formula is as follows:
where k is the branch number of the search, d k The distance between the fault point and the head end of the line is searched according to the set step length and the change of the distance length,
positive sequence voltage for n uPMU collection in the power grid>
Is the system negative sequence voltage;
the matching formula is specifically as follows:
wherein, the first and the second end of the pipe are connected with each other,
when the matching formula is established, the fault current is completely matched, and a fault branch and a fault position d are output k The value is obtained. />
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