CN110994571B - Fault grading processing method suitable for alternating current-direct current hybrid power distribution network - Google Patents
Fault grading processing method suitable for alternating current-direct current hybrid power distribution network Download PDFInfo
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Abstract
A fault classification processing method applicable to an alternating current-direct current hybrid power distribution network is used for classifying four levels of faults possibly occurring in the alternating current-direct current hybrid power distribution network according to properties and influences of the faults, and through scientific classification and processing of different faults possibly occurring in the alternating current-direct current hybrid power distribution network, correct judgment and processing schemes can be rapidly made after the faults occur, so that the power supply reliability of the alternating current-direct current hybrid power distribution network is improved, the faults are classified, the fault processing schemes are determined, rapid power restoration is facilitated, and the fault classification processing method has the advantages of being scientific and reasonable, strong in applicability, good in application effect and the like.
Description
Technical Field
The invention relates to a fault grading system of a hybrid power distribution network, in particular to a fault grading processing method suitable for an alternating current-direct current hybrid power distribution network.
Background
The economy of China develops at a high speed, the demand and the dependence on electric power are increased day by day, along with the continuous enlargement of the scale of a power grid and the increasing complexity of the structure, the safety, the reliability and the economic operation of a power system occupy more and more important positions in national economy and people life, and most of fault power failure is caused by the fault of a power distribution network, so the reasonable fault processing method of the power distribution network has important significance for improving the reliability of power supply.
With the development of new energy, new materials and power electronic technologies, the direct current power distribution technology is also researched and developed, and the alternating current-direct current hybrid power distribution network becomes the key development direction of the future power distribution network. Compared with a single alternating-current power distribution network and a single direct-current power distribution network, the alternating-current and direct-current hybrid power distribution network has more various and complex fault working conditions, not only contains single alternating-current power distribution network faults or direct-current power distribution network faults, but also can generate fault working conditions of alternating current and direct current mutual interference, reasonably classifies the faults, and definitely determines that the processing flow becomes an important factor for reducing the fault processing period of the power distribution network, and also is an important factor for improving the toughness of a power system and the power supply reliability of the power system.
The existing power distribution network fault processing method is only limited to faults occurring in an alternating current power distribution network, and related documents and practical applications of fault grading processing methods suitable for alternating current and direct current hybrid power distribution network faults are not found so far.
Disclosure of Invention
The invention aims at the fault of the alternating current-direct current hybrid power distribution network, which is not related in the prior art, and creatively provides a fault grading processing method suitable for the alternating current-direct current hybrid power distribution network.
The technical scheme adopted by the invention is as follows:
1. a fault grading processing method suitable for an alternating current-direct current hybrid power distribution network is characterized by comprising the following steps: it comprises the following steps:
1) and (3) evaluating the fault state of the AC/DC hybrid power distribution network:
according to the information provided by the relay protection device, after the AC/DC hybrid power distribution network is judged to have a fault, the fault state of the power distribution network is evaluated, and the evaluation comprises the following steps:
(1) information summarization is carried out on protection actions, circuit breaker tripping on-off quantity, voltage and current electrical quantity information in the AC/DC hybrid power distribution network;
(2) according to the information summary in the step (1), adopting an immune genetic algorithm to check the accuracy of the information summary to obtain data information;
(3) judging the running state of the AC/DC hybrid power distribution network according to the data information obtained in the step (2) in the step 1), and determining the influence range of the fault;
2) carrying out grading treatment on faults of the AC/DC hybrid power distribution network:
according to fault state evaluation of the alternating current-direct current hybrid power distribution network in the step 1), fault classification processing is carried out on the power distribution network, wherein the first-level fault, the second-level fault and the third-level fault only comprise faults in the alternating current network and faults in the direct current network, the faults in the alternating current-direct current converter link are not considered, the fourth-level fault comprises faults in the alternating current network and faults in the direct current network, and the faults in the alternating current-direct current converter link are classified according to the following conditions according to the nature and influence of the faults:
(1) first-stage failure: the fault influence is only limited in an AC network or a DC network;
(2) secondary failure: the alternating current and direct current networks are in fault mutual interference, but the fault mutual interference is not enough to influence the stable operation of the system;
(3) and (3) three-stage fault: the AC and DC networks are interfered with each other due to faults and only influence the stable operation of an AC or DC system;
(4) four-stage failure: the AC and DC networks are interfered with each other due to faults and influence the stable operation of an AC and DC system;
3) according to the faults at all levels in the step 2), a mechanism for processing the AC/DC hybrid power distribution network is as follows:
(1) in the mixed distribution network of alternating current-direct current, the one-level fault handling mechanism takes place in the alternating current network:
firstly, fault positioning: fault line selection, fault phase selection and fault distance measurement;
fault isolation: based on the distribution network dispatching automation working mode, the isolation scheme is determined in a centralized or decentralized mode;
thirdly, fault recovery: considering the operation states of the distributed power supply and the microgrid, sequentially carrying out rack evaluation, load transfer, subsystem reconstruction and system reconstruction;
(2) in the AC-DC hybrid power distribution network, a primary fault processing mechanism occurs in the DC network:
fault isolation and fault location: comprehensively considering the reliability and the economy of power supply, and determining the sequence of fault isolation and fault location, wherein the fault location comprises fault line selection, fault pole selection and fault distance measurement;
secondly, fault recovery: considering the operation states of the distributed power supply and the microgrid, sequentially carrying out rack evaluation, load transfer, subsystem reconstruction and system reconstruction;
(3) in the mixed distribution network of alternating current-direct current, the two-level fault processing mechanism takes place in the alternating current network:
firstly, locking or electrically isolating the AC-DC converter;
secondly, fault positioning: fault line selection and fault distance measurement are sequentially realized;
thirdly, fault isolation: fault isolation is realized in a centralized or dispersed mode based on the distribution network dispatching automation working mode;
fourthly, restoring the link of the AC-DC converter;
fault recovery: considering the operation states of the distributed power supply and the microgrid, sequentially carrying out rack evaluation, load transfer, subsystem reconstruction and system reconstruction;
(4) in the mixed distribution network of alternating current-direct current, the second grade fault handling mechanism takes place in the direct current net:
firstly, locking or electrically isolating the AC-DC converter;
fault isolation and fault location: comprehensively considering the reliability and the economy of power supply, and determining the sequence of fault isolation and fault location, wherein the fault location comprises fault line selection and fault distance measurement;
restoring the link of the AC-DC converter;
fourthly, fault recovery: considering the operation states of the distributed power supply and the microgrid, sequentially carrying out rack evaluation, load transfer, subsystem reconstruction and system reconstruction;
(5) in the mixed distribution network of alternating current-direct current, three grades of fault handling mechanisms take place in the alternating current network:
firstly, locking or electrically isolating the AC-DC converter;
secondly, fault positioning: fault line selection and fault distance measurement are carried out in sequence;
thirdly, fault isolation: fault isolation is realized in a centralized or dispersed mode based on the distribution network dispatching automation working mode;
fourthly, restoring the link of the AC-DC converter;
fault recovery: considering a distributed power supply and a microgrid, sequentially carrying out rack evaluation, load transfer, black start, subsystem reconstruction and system reconstruction;
(6) in the mixed distribution network of alternating current-direct current, the tertiary fault handling mechanism takes place in the direct current net:
firstly, an AC-DC converter is locked or electrically isolated:
secondly, fault isolation is carried out;
thirdly, fault positioning: fault line selection and fault distance measurement are carried out in sequence;
fourthly, restoring the link of the AC-DC converter;
fault recovery: considering the operation states of the distributed power supply and the microgrid, sequentially carrying out rack evaluation, load transfer, black start, subsystem reconstruction and system reconstruction;
(7) in the mixed distribution network of alternating current-direct current, take place four grades of fault handling mechanisms in the alternating current network:
firstly, locking or electrically isolating the AC-DC converter;
secondly, fault positioning: fault line selection and fault distance measurement are carried out in sequence;
thirdly, fault isolation: fault isolation is realized in a centralized or dispersed mode based on the distribution network dispatching automation working mode;
fourthly, restoring the link of the AC-DC converter;
fault recovery: considering the operation states of the distributed power supply and the microgrid, sequentially carrying out rack evaluation, load transfer, black start, subsystem reconstruction or system reconstruction;
(8) in the mixed distribution network of alternating current-direct current, take place four grades of fault handling mechanisms in the direct current net:
firstly, an AC-DC converter is locked or electrically isolated:
secondly, fault isolation is carried out;
thirdly, fault positioning: fault line selection and fault distance measurement are carried out in sequence;
fourthly, restoring the link of the AC-DC converter;
fault recovery: considering the operation states of the distributed power supply and the microgrid, sequentially carrying out rack evaluation, load transfer, black start, subsystem reconstruction or system reconstruction;
(9) in an alternating current-direct current hybrid power distribution network, a four-stage fault handling mechanism caused by a link fault of an alternating current-direct current converter is as follows:
firstly, an alternating current-direct current converter is electrically isolated;
a whole network recovery strategy: and considering the distributed power supply of the AC/DC sub-network and the running state of the micro-network, sequentially carrying out rack evaluation, load transfer, black start, respective reconstruction of the AC/DC sub-system and attempt of whole-network recovery.
The network frame evaluation means that a network topology structure is determined based on the state of a breaker switch; the load transfer refers to realizing power supply of a replacement loop of a power failure load under the condition of avoiding overload operation of a line or a transformer based on a power flow optimization result; the subsystem reconfiguration means that after fault isolation and fault positioning are completed, the AC subsystem or the DC subsystem recovers the network power supply of the non-fault area; the system reconstruction means that after the direct current subsystem and the alternating current subsystem are respectively reconstructed, the whole alternating current-direct current hybrid power distribution network non-fault area is powered up again.
The black start comprises the following steps:
1) the power supply starting of voltage support can be realized;
2) the started power supply supplies power to other power supplies in the subsystem;
3) recovering power supply by the load of the non-fault area to realize subsystem reconstruction;
4) the normal power supply subsystem supplies power to the isolated subsystem;
5) and (5) attempting to recover all load power supply of the non-fault area of the AC/DC hybrid power distribution network.
The comprehensive consideration of power supply reliability and economy and the determination of the sequence of fault isolation and fault location are as follows:
defining an objective function
max{min[λ1(X),λ2(X)]}
Constraint conditions
Wherein X is (X)1,x2,…,xm) Representing decision variables, i.e. the line or network on which fault localization, fault isolation needs to be performed, the equality constraint h (x) ═ 0 includes: the active power and the reactive power are balanced, and the inequality constraint g (X) is less than or equal to 0, which comprises the following steps: the economic loss caused by voltage, current, heating and depreciation cost and power failure of the power system equipment influenced by the fault, and the membership function lambda1(X)、λ2(X) represents the degree to which the economic objective and the reliability objective are close to the optimum values, and respectively correspond to the objective function f1And f2And the membership function values are all in [0,1 ]]To (c) to (d);
wherein f is1.minAnd f2.maxRespectively corresponding to the minimum equipment depreciation cost obtained by taking the equipment depreciation cost as an optimization target and the corresponding maximum power failure loss; f. of1.maxAnd f2.minRespectively corresponding to the maximum equipment depreciation cost obtained by taking the power failure loss as an optimization target and the corresponding minimum power failure loss.
The invention discloses a fault grading processing method suitable for an alternating current-direct current hybrid power distribution network, which has the beneficial effects that:
1. a fault classification processing method applicable to an alternating current-direct current hybrid power distribution network is used for classifying faults which may occur in the alternating current-direct current hybrid power distribution network into four classes according to properties and influences of the faults, wherein the first-class faults, the second-class faults and the third-class faults respectively comprise two fault types of faults in an alternating current network and faults in a direct current network, the fourth-class faults comprise three fault types of faults in the alternating current network, faults in the direct current network and faults in an AC/DC converter link, nine fault types are involved in the whole, and through scientific classification and processing of different faults which may occur in the alternating current-direct current hybrid power distribution network, correct judgment and processing schemes can be rapidly made after the faults occur, so that the power supply reliability of the alternating current-direct current hybrid power distribution network is improved;
2. a fault grading processing method suitable for an alternating current-direct current hybrid power distribution network standardizes a coping process after the alternating current-direct current hybrid power distribution network fails, scientifically grades the faults, so that a fault processing scheme is determined, quick power supply recovery is facilitated, and the method has the advantages of being scientific and reasonable, strong in applicability, good in application effect and the like.
Drawings
FIG. 1 is a flow chart of a fault grading processing method suitable for an AC/DC hybrid power distribution network;
fig. 2 shows that the embodiment adopts a fault classification processing method suitable for the ac/dc hybrid power distribution network to classify the types of the faults and the fault positions.
Detailed Description
The present invention will be described in further detail with reference to the following drawings and specific embodiments, which are described herein for illustrative purposes only and are not intended to limit the present invention.
Referring to figure 1:
1. a fault grading processing method suitable for an alternating current-direct current hybrid power distribution network is characterized by comprising the following steps: it comprises the following steps:
1) and (3) evaluating the fault state of the AC/DC hybrid power distribution network:
according to the information provided by the relay protection device, after the AC/DC hybrid power distribution network is judged to have a fault, the fault state of the power distribution network is evaluated, and the evaluation comprises the following steps:
(1) information summarization is carried out on protection actions, circuit breaker tripping on-off quantity, voltage and current electrical quantity information in the AC/DC hybrid power distribution network;
(2) according to the information summary in the step (1), adopting an immune genetic algorithm to check the accuracy of the information summary to obtain data information;
(3) judging the running state of the AC/DC hybrid power distribution network according to the data information obtained in the step (2) in the step 1), and determining the influence range of the fault;
2) carrying out grading treatment on faults of the AC/DC hybrid power distribution network:
according to fault state evaluation of the alternating current-direct current hybrid power distribution network in the step 1), fault classification processing is carried out on the power distribution network, wherein the first-level fault, the second-level fault and the third-level fault only comprise faults in the alternating current network and faults in the direct current network, the faults in the alternating current-direct current converter link are not considered, the fourth-level fault comprises faults in the alternating current network and faults in the direct current network, and the faults in the alternating current-direct current converter link are classified according to the following conditions according to the nature and influence of the faults:
(1) first-stage failure: the fault influence is only limited in an AC network or a DC network;
(2) secondary failure: the alternating current and direct current networks are in fault mutual interference, but the fault mutual interference is not enough to influence the stable operation of the system;
(3) and (3) three-stage fault: the AC and DC networks are interfered with each other due to faults and only influence the stable operation of an AC or DC system;
(4) four-stage failure: the AC and DC networks are interfered with each other due to faults and influence the stable operation of an AC and DC system;
3) according to the faults at all levels in the step 2), a mechanism for processing the AC/DC hybrid power distribution network is as follows:
(1) in the mixed distribution network of alternating current-direct current, the one-level fault handling mechanism takes place in the alternating current network:
firstly, fault positioning: fault line selection, fault phase selection and fault distance measurement;
fault isolation: based on the distribution network dispatching automation working mode, the isolation scheme is determined in a centralized or decentralized mode;
thirdly, fault recovery: considering the operation states of the distributed power supply and the microgrid, sequentially carrying out rack evaluation, load transfer, subsystem reconstruction and system reconstruction;
(2) in the AC-DC hybrid power distribution network, a primary fault processing mechanism occurs in the DC network:
fault isolation and fault location: comprehensively considering the reliability and the economy of power supply, and determining the sequence of fault isolation and fault location, wherein the fault location comprises fault line selection, fault pole selection and fault distance measurement;
secondly, fault recovery: considering the operation states of the distributed power supply and the microgrid, sequentially carrying out rack evaluation, load transfer, subsystem reconstruction and system reconstruction;
(3) in the mixed distribution network of alternating current-direct current, the two-level fault processing mechanism takes place in the alternating current network:
firstly, locking or electrically isolating the AC-DC converter;
secondly, fault positioning: fault line selection and fault distance measurement are sequentially realized;
thirdly, fault isolation: fault isolation is realized in a centralized or dispersed mode based on the distribution network dispatching automation working mode;
fourthly, restoring the link of the AC-DC converter;
fault recovery: considering the operation states of the distributed power supply and the microgrid, sequentially carrying out rack evaluation, load transfer, subsystem reconstruction and system reconstruction;
(4) in the mixed distribution network of alternating current-direct current, the second grade fault handling mechanism takes place in the direct current net:
firstly, locking or electrically isolating the AC-DC converter;
fault isolation and fault location: comprehensively considering the reliability and the economy of power supply, and determining the sequence of fault isolation and fault location, wherein the fault location comprises fault line selection and fault distance measurement;
restoring the link of the AC-DC converter;
fourthly, fault recovery: considering the operation states of the distributed power supply and the microgrid, sequentially carrying out rack evaluation, load transfer, subsystem reconstruction and system reconstruction;
(5) in the mixed distribution network of alternating current-direct current, three grades of fault handling mechanisms take place in the alternating current network:
firstly, locking or electrically isolating the AC-DC converter;
secondly, fault positioning: fault line selection and fault distance measurement are carried out in sequence;
thirdly, fault isolation: fault isolation is realized in a centralized or dispersed mode based on the distribution network dispatching automation working mode;
fourthly, restoring the link of the AC-DC converter;
fault recovery: considering a distributed power supply and a microgrid, sequentially carrying out rack evaluation, load transfer, black start, subsystem reconstruction and system reconstruction;
(6) in the mixed distribution network of alternating current-direct current, the tertiary fault handling mechanism takes place in the direct current net:
firstly, an AC-DC converter is locked or electrically isolated:
secondly, fault isolation is carried out;
thirdly, fault positioning: fault line selection and fault distance measurement are carried out in sequence;
fourthly, restoring the link of the AC-DC converter;
fault recovery: considering the operation states of the distributed power supply and the microgrid, sequentially carrying out rack evaluation, load transfer, black start, subsystem reconstruction and system reconstruction;
(7) in the mixed distribution network of alternating current-direct current, take place four grades of fault handling mechanisms in the alternating current network:
firstly, locking or electrically isolating the AC-DC converter;
secondly, fault positioning: fault line selection and fault distance measurement are carried out in sequence;
thirdly, fault isolation: fault isolation is realized in a centralized or dispersed mode based on the distribution network dispatching automation working mode;
fourthly, restoring the link of the AC-DC converter;
fault recovery: considering the operation states of the distributed power supply and the microgrid, sequentially carrying out rack evaluation, load transfer, black start, subsystem reconstruction or system reconstruction;
(8) in the mixed distribution network of alternating current-direct current, take place four grades of fault handling mechanisms in the direct current net:
firstly, an AC-DC converter is locked or electrically isolated:
secondly, fault isolation is carried out;
thirdly, fault positioning: fault line selection and fault distance measurement are carried out in sequence;
fourthly, restoring the link of the AC-DC converter;
fault recovery: considering the operation states of the distributed power supply and the microgrid, sequentially carrying out rack evaluation, load transfer, black start, subsystem reconstruction or system reconstruction;
(9) in an alternating current-direct current hybrid power distribution network, a four-stage fault handling mechanism caused by a link fault of an alternating current-direct current converter is as follows:
firstly, an alternating current-direct current converter is electrically isolated;
a whole network recovery strategy: and considering the distributed power supply of the AC/DC sub-network and the running state of the micro-network, sequentially carrying out rack evaluation, load transfer, black start, respective reconstruction of the AC/DC sub-system and attempt of whole-network recovery.
The network frame evaluation means that a network topology structure is determined based on the state of a breaker switch; the load transfer refers to realizing power supply of a replacement loop of a power failure load under the condition of avoiding overload operation of a line or a transformer based on a power flow optimization result; the subsystem reconfiguration means that after fault isolation and fault positioning are completed, the AC subsystem or the DC subsystem recovers the network power supply of the non-fault area; the system reconstruction means that after the direct current subsystem and the alternating current subsystem are respectively reconstructed, the whole alternating current-direct current hybrid power distribution network non-fault area is powered up again.
The black start comprises the following steps:
1) the power supply starting of voltage support can be realized;
2) the started power supply supplies power to other power supplies in the subsystem;
3) recovering power supply by the load of the non-fault area to realize subsystem reconstruction;
4) the normal power supply subsystem supplies power to the isolated subsystem;
5) and (5) attempting to recover all load power supply of the non-fault area of the AC/DC hybrid power distribution network.
The comprehensive consideration of power supply reliability and economy and the determination of the sequence of fault isolation and fault location are as follows:
defining an objective function
max{min[λ1(X),λ2(X)]}
Constraint conditions
Wherein X is (X)1,x2,…,xm) Representing decision variables, i.e. the line or network on which fault localization, fault isolation needs to be performed, the equality constraint h (x) ═ 0 includes: the active power and the reactive power are balanced, and the inequality constraint g (X) is less than or equal to 0, which comprises the following steps: the economic loss caused by voltage, current, heating and depreciation cost and power failure of the power system equipment influenced by the fault, and the membership function lambda1(X)、λ2(X) represents the degree to which the economic objective and the reliability objective are close to the optimum values, and respectively correspond to the objective function f1And f2And the membership function values are all in [0,1 ]]To (c) to (d);
wherein f is1.minAnd f2.maxCorresponding to the minimum depreciation cost of the equipment and the corresponding costThe maximum power failure loss; f. of1.maxAnd f2.minRespectively corresponding to the maximum equipment depreciation cost obtained by taking the power failure loss as an optimization target and the corresponding minimum power failure loss.
Example 1:
with reference to figure 2 of the drawings,
1) when a single-phase grounding short-circuit fault (the neutral point of the AC side of the converter is not grounded) occurs on the AC side of the AC-DC hybrid power distribution network or a short-circuit fault occurs in a low-voltage AC distribution sub-network on the AC side, the fault on the AC side is limited in the AC network. At the moment, the fault type is divided into a first-level fault in the alternating current network;
2) when a single-pole grounding short-circuit fault occurs on the direct-current side of the alternating-current and direct-current hybrid power distribution network or a short-circuit fault occurs in a low-voltage direct-current power distribution electronic network on the direct-current side, the fault on the direct-current side is limited in the direct-current network. At the moment, the fault type is divided into a first-stage fault in the direct current network;
3) when the AC side k of the AC/DC hybrid power distribution network1To (ac DG feeder) or k2When an interphase short circuit fault occurs at a position (an alternating current load feeder), the fault causes disturbance to a direct current side, and the stable operation of a system cannot be influenced after the fault is isolated. At the moment, the fault type is divided into two-stage faults in the AC network;
4) when the direct current side k of the alternating current-direct current hybrid power distribution network3Position (DC DG feeder) or k4Position (energy storage device feeder) or k5Position (DC load feeder) or k6An interelectrode short-circuit fault occurs at the position (an alternating current load feeder line), the fault disturbs an alternating current side, and the stable operation of the system cannot be influenced after the fault is isolated. At the moment, dividing the fault type into secondary faults in the direct current network;
5) when the AC side k of the AC/DC hybrid power distribution network7An interphase short circuit fault occurs at a position (an alternating current feeder), and the fault causes disturbance to a direct current side and influences the stable operation of the alternating current side. At the moment, the fault type is divided into three-level faults in the alternating current network;
6) when the direct current side k of the alternating current-direct current hybrid power distribution network8An interphase short-circuit fault occurs at the position of the (direct current feeder line), and the fault causes direct current sideAnd the stable operation of the direct current side is affected. At the moment, the fault type is divided into three stages of faults in the direct current network;
7) k when AC/DC hybrid distribution network9An inter-phase short circuit fault occurs at the place (alternating current bus), the fault causes disturbance to the direct current side, and stable operation of the alternating current side and the direct current side is influenced simultaneously. At the moment, dividing the fault into four-stage faults in the AC network;
8) k when AC/DC hybrid distribution network10An inter-phase short circuit fault occurs at the place (direct current bus), the fault causes disturbance to the direct current side, and stable operation of the alternating current side and the direct current side is influenced simultaneously. At the moment, dividing the fault into four-stage faults in the AC network;
9) when an AC/DC converter link of the AC/DC hybrid power distribution network connecting an AC network and a DC network breaks down, the fault affects the stable operation of the AC side and the DC side at the same time. And dividing the fault into four-stage faults caused by the fault of the AC/DC converter link.
The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, several modifications and decorations can be made without departing from the invention, and these modifications and decorations should also be regarded as the protection scope of the present invention.
Claims (4)
1. A fault grading processing method suitable for an alternating current-direct current hybrid power distribution network is characterized by comprising the following steps: it comprises the following steps:
1) and (3) evaluating the fault state of the AC/DC hybrid power distribution network:
according to the information provided by the relay protection device, after the AC/DC hybrid power distribution network is judged to have a fault, the fault state of the power distribution network is evaluated, and the evaluation comprises the following steps:
(1) information summarization is carried out on protection actions, circuit breaker tripping on-off quantity, voltage and current electrical quantity information in the AC/DC hybrid power distribution network;
(2) according to the information summary in the step (1), adopting an immune genetic algorithm to check the accuracy of the information summary to obtain data information;
(3) judging the running state of the AC/DC hybrid power distribution network according to the data information obtained in the step (2) in the step 1), and determining the influence range of the fault;
2) carrying out grading treatment on faults of the AC/DC hybrid power distribution network:
according to fault state evaluation of the alternating current-direct current hybrid power distribution network in the step 1), fault classification processing is carried out on the power distribution network, wherein the first-level fault, the second-level fault and the third-level fault only comprise faults in the alternating current network and faults in the direct current network, the faults in the alternating current-direct current converter link are not considered, the fourth-level fault comprises faults in the alternating current network and faults in the direct current network, and the faults in the alternating current-direct current converter link are classified according to the following conditions according to the nature and influence of the faults:
(1) first-stage failure: the fault influence is only limited in an AC network or a DC network;
(2) secondary failure: the alternating current and direct current networks are in fault mutual interference, but the fault mutual interference is not enough to influence the stable operation of the system;
(3) and (3) three-stage fault: the AC and DC networks are interfered with each other due to faults and only influence the stable operation of an AC or DC system;
(4) four-stage failure: the AC and DC networks are interfered with each other due to faults and influence the stable operation of an AC and DC system;
3) according to the faults at all levels in the step 2), a mechanism for processing the AC/DC hybrid power distribution network is as follows:
(1) in the mixed distribution network of alternating current-direct current, the one-level fault handling mechanism takes place in the alternating current network:
firstly, fault positioning: fault line selection, fault phase selection and fault distance measurement;
fault isolation: based on the distribution network dispatching automation working mode, the isolation scheme is determined in a centralized or decentralized mode;
thirdly, fault recovery: considering the operation states of the distributed power supply and the microgrid, sequentially carrying out rack evaluation, load transfer, subsystem reconstruction and system reconstruction;
(2) in the AC-DC hybrid power distribution network, a primary fault processing mechanism occurs in the DC network:
fault isolation and fault location: comprehensively considering the reliability and the economy of power supply, and determining the sequence of fault isolation and fault location, wherein the fault location comprises fault line selection, fault pole selection and fault distance measurement;
secondly, fault recovery: considering the operation states of the distributed power supply and the microgrid, sequentially carrying out rack evaluation, load transfer, subsystem reconstruction and system reconstruction;
(3) in the mixed distribution network of alternating current-direct current, the two-level fault processing mechanism takes place in the alternating current network:
firstly, locking or electrically isolating the AC-DC converter;
secondly, fault positioning: fault line selection and fault distance measurement are sequentially realized;
thirdly, fault isolation: fault isolation is realized in a centralized or dispersed mode based on the distribution network dispatching automation working mode;
fourthly, restoring the link of the AC-DC converter;
fault recovery: considering the operation states of the distributed power supply and the microgrid, sequentially carrying out rack evaluation, load transfer, subsystem reconstruction and system reconstruction;
(4) in the mixed distribution network of alternating current-direct current, the second grade fault handling mechanism takes place in the direct current net:
firstly, locking or electrically isolating the AC-DC converter;
fault isolation and fault location: comprehensively considering the reliability and the economy of power supply, and determining the sequence of fault isolation and fault location, wherein the fault location comprises fault line selection and fault distance measurement;
restoring the link of the AC-DC converter;
fourthly, fault recovery: considering the operation states of the distributed power supply and the microgrid, sequentially carrying out rack evaluation, load transfer, subsystem reconstruction and system reconstruction;
(5) in the mixed distribution network of alternating current-direct current, three grades of fault handling mechanisms take place in the alternating current network:
firstly, locking or electrically isolating the AC-DC converter;
secondly, fault positioning: fault line selection and fault distance measurement are carried out in sequence;
thirdly, fault isolation: fault isolation is realized in a centralized or dispersed mode based on the distribution network dispatching automation working mode;
fourthly, restoring the link of the AC-DC converter;
fault recovery: considering a distributed power supply and a microgrid, sequentially carrying out rack evaluation, load transfer, black start, subsystem reconstruction and system reconstruction;
(6) in the mixed distribution network of alternating current-direct current, the tertiary fault handling mechanism takes place in the direct current net:
firstly, an AC-DC converter is locked or electrically isolated:
secondly, fault isolation is carried out;
thirdly, fault positioning: fault line selection and fault distance measurement are carried out in sequence;
fourthly, restoring the link of the AC-DC converter;
fault recovery: considering the operation states of the distributed power supply and the microgrid, sequentially carrying out rack evaluation, load transfer, black start, subsystem reconstruction and system reconstruction;
(7) in the mixed distribution network of alternating current-direct current, take place four grades of fault handling mechanisms in the alternating current network:
firstly, locking or electrically isolating the AC-DC converter;
secondly, fault positioning: fault line selection and fault distance measurement are carried out in sequence;
thirdly, fault isolation: fault isolation is realized in a centralized or dispersed mode based on the distribution network dispatching automation working mode;
fourthly, restoring the link of the AC-DC converter;
fault recovery: considering the operation states of the distributed power supply and the microgrid, sequentially carrying out rack evaluation, load transfer, black start, subsystem reconstruction or system reconstruction;
(8) in the mixed distribution network of alternating current-direct current, take place four grades of fault handling mechanisms in the direct current net:
firstly, an AC-DC converter is locked or electrically isolated:
secondly, fault isolation is carried out;
thirdly, fault positioning: fault line selection and fault distance measurement are carried out in sequence;
fourthly, restoring the link of the AC-DC converter;
fault recovery: considering the operation states of the distributed power supply and the microgrid, sequentially carrying out rack evaluation, load transfer, black start, subsystem reconstruction or system reconstruction;
(9) in an alternating current-direct current hybrid power distribution network, a four-stage fault handling mechanism caused by a link fault of an alternating current-direct current converter is as follows:
firstly, an alternating current-direct current converter is electrically isolated;
a whole network recovery strategy: and considering the distributed power supply of the AC/DC sub-network and the running state of the micro-network, sequentially carrying out rack evaluation, load transfer, black start, respective reconstruction of the AC/DC sub-system and attempt of whole-network recovery.
2. The fault classification processing method applicable to the alternating current-direct current hybrid power distribution network according to claim 1, wherein the grid evaluation means that a network topology structure is determined based on a breaker switch state; the load transfer refers to realizing power supply of a replacement loop of a power failure load under the condition of avoiding overload operation of a line or a transformer based on a power flow optimization result; the subsystem reconfiguration means that after fault isolation and fault positioning are completed, the AC subsystem or the DC subsystem recovers the network power supply of the non-fault area; the system reconstruction means that after the direct current subsystem and the alternating current subsystem are respectively reconstructed, the whole alternating current-direct current hybrid power distribution network non-fault area is powered up again.
3. The fault classification processing method suitable for the alternating current-direct current hybrid power distribution network according to claim 1, wherein the black start comprises the following steps:
1) the power supply starting of voltage support can be realized;
2) the started power supply supplies power to other power supplies in the subsystem;
3) recovering power supply by the load of the non-fault area to realize subsystem reconstruction;
4) the normal power supply subsystem supplies power to the isolated subsystem;
5) and (5) attempting to recover all load power supply of the non-fault area of the AC/DC hybrid power distribution network.
4. The fault grading processing method suitable for the alternating current-direct current hybrid power distribution network according to claim 1, wherein the step of determining the sequence of fault isolation and fault location by comprehensively considering power supply reliability and economy comprises the following steps:
defining an objective function
max{min[λ1(X),λ2(X)]}
Constraint conditions
Wherein X is (X)1,x2,…,xm) Representing decision variables, i.e. the line or network on which fault localization, fault isolation needs to be performed, the equality constraint h (x) ═ 0 includes: the active power and the reactive power are balanced, and the inequality constraint g (X) is less than or equal to 0, which comprises the following steps: the economic loss caused by voltage, current, heating and depreciation cost and power failure of the power system equipment influenced by the fault, and the membership function lambda1(X)、λ2(X) represents the degree to which the economic objective and the reliability objective are close to the optimum values, and respectively correspond to the objective function f1And f2And the membership function values are all in [0,1 ]]To (c) to (d);
wherein f is1.minAnd f2.maxRespectively corresponding to the minimum equipment depreciation cost obtained by taking the equipment depreciation cost as an optimization target and the corresponding maximum power failure loss; f. of1.maxAnd f2.minRespectively corresponding to the maximum equipment depreciation cost obtained by taking the power failure loss as an optimization target and the corresponding minimum power failure loss.
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