A power distribution network distributed fault recovery method based on flexible soft switch and liaison switch cooperation

Abstract

The application provides a power distribution network distributed fault recovery method based on flexible soft switches and tie switches, which comprises the following steps: firstly, a power supply-switch-load topology search method considering SOP and TS is established; then, power supply-switch-load topology is used to realize system power capacity estimation, and the load recovery level is determined according to the estimated power capacity; then, one-stage system power adjustment is carried out based on the estimated system power capacity, and the SOP port power instruction is modified according to the predicted load power; finally, it is judged whether the voltage of the low-voltage distribution network terminal feeder is out of limit, and if the voltage is out of limit, two-stage system power adjustment considering the SOP is carried out. The method can realize distributed fault recovery by relying on the cooperation of SOP and TS after the fault of the low-voltage distribution network, and can balance the system recovery speed and the load recovery amount on the premise of ensuring the safe and reliable operation of the system fault recovery.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of coordinated fault recovery of flexible interconnected distribution network, in particular to a distribution network distributed fault recovery method based on flexible soft switch and contact switch coordination. BACKGROUND

[0002] Renewable new energy has become a future development trend, and high-proportion new energy access distribution network has gradually become a key carrier for China's current energy transformation. When a large-scale renewable energy cluster is connected to the distribution network, due to the intermittency and volatility of power output and the complexity of system voltage frequency control, the requirement for fault recovery capability of the distribution network is significantly improved. The existing distribution network fault recovery scheme mainly transfers the load through the traditional contact switch (TS), and the system can only be powered by a single contact switch. This recovery method has limited load recovery capacity, and power cannot be flexibly exchanged between regions. Therefore, how to effectively solve the low-voltage distribution network terminal load power supply recovery has become a problem to be solved.

[0003] When a fault occurs in the distribution network, the traditional centralized fault recovery method needs to model the global information such as voltage and power of the low-voltage distribution network, which will lead to a long centralized calculation and decision-making process, and the decision result is a steady-state recovery scheme, which does not involve the transient process. In addition, if the centralized control center fails, it will cause large-scale power failure in the region, so it is necessary to study the distributed fault recovery method. The flexible soft switch (SOP) is a key device connecting each distribution network, which can realize flexible power exchange between power supply areas during a fault. Therefore, how to coordinate the flexible soft switch with the contact switch has become a problem to be solved. In addition, due to the characteristics of distributed fault recovery, global information cannot be obtained, and there may be situations where the load recovery after reclosing does not meet the system operation constraints, resulting in voltage out-of-limit problems during the fault recovery process. Therefore, how to ensure the safe operation of the system voltage under the premise of realizing the maximum load recovery through distributed fault recovery has become a challenge. SUMMARY

[0004] (I) Technical problems solved

[0005] In view of the deficiencies and gaps of the prior art, the present application provides a distribution network distributed fault recovery method based on flexible soft switch and contact switch coordination to solve the problems in the background art.

[0006] (II) Technical solutions

[0007] To achieve the above purpose, the present application is realized by the following technical solutions:

[0008] In one aspect, a power distribution network distributed fault recovery method based on the cooperation of flexible soft switches and tie switches is provided, comprising:

[0009] Step A: Establishing power supply nodes, a set of SOP converter nodes connected with the power failure area, and a set of TS load nodes connected with the power failure area, performing breadth-first search through the above node sets by applying Dijkstra algorithm, respectively calculating the shortest distances from each power supply to the SOP converter nodes connected with the power failure area and the shortest distances from each power supply to the TS load nodes connected with the power failure area, determining the TS position according to the optimal TS determination logic to obtain a power-supply-switch-load topology;

[0010] Step B: For the obtained power-supply-switch-load topology, each lower-level agent power supply point transmits its remaining capacity information to the connected upper-level agent, and the upper-level agent performs a system capacity estimation decision process;

[0011] Step C: Realizing one-stage system power adjustment based on the obtained system power supply capacity and load predicted power to achieve capacity sharing, and adjusting the SOP operating capacity based on the load power factor angle;

[0012] Step D: Judging whether there is a voltage out-of-limit situation at the connection of the low-voltage distribution network terminal feeder in the power distribution network distributed fault recovery process, if there is a voltage out-of-limit, performing two-stage system power adjustment based on the SOP, obtaining the power adjustment amount by subtracting the out-of-limit voltage value from the voltage limit value, and adjusting the PCC voltage to be within the normal operating limit.

[0013] Further, according to the step A, the power-supply-switch-load topology is established by the following steps A01 to A03:

[0014] Step A01: Establishing a set of power supply nodes, a set of SOP converter nodes connected with the power failure area, and a set of TS nodes connected with the power failure area, respectively:

[0015] V sourse ={v s1 ,…,v si ,…,v sn}

[0016] V sop ={v d1 ,…,v dj ,…,v dm}

[0017] V TS ={v t1 ,…,v tk ,…,v tp}

[0018] In the formula, V siFor the i-th power node number, n is the number of power supply; v dj For the j-th SOP converter node number connected with the off region, m is the number of connected converters; v tk For the k-th TS load node number connected with the off region, p is the number of connected TS.

[0019] Step A02: taking V sourse point set as the starting point, V sop and V TS point set as the end point, taking one of the power supply points as the starting point, constantly searching for the node with the shortest path distance from the starting point among the unmarked points, and marking it, until all nodes are marked, thereby obtaining the distance matrix of V sourse and V sop , V sourse and V TS :

[0020]

[0021] In the formula, d(v s1 , v d1 ) represents the distance between nodes v s1 and v d1 .

[0022] Step A03: after obtaining the above matrix, according to the shortest path principle, the shortest distance of each row of the matrix is the power supply-SOP topology and the power supply-TS topology. According to the power supply-TS topology, the optimal TS closing point is selected. The optimal TS structure determination logic is as follows:

[0023] 1) Preferentially selecting TS connected only with TS and not with any SOP;

[0024] 2) If the connected power supply is connected with SOP, for multi-port SOP, selecting the TS connected with the SOP with more ports;

[0025] 3) Selecting the region with the highest power blocking degree for power supply through TS under the condition that the number of SOP ports is consistent.

[0026] Further, in step B, the source capacity estimation method considering the power supply-switch-load topology is designed.

[0027] Step B01: After obtaining the above topology, each lower-level agent power supply point transmits its remaining capacity information to the connected upper-level agent, and the upper-level agent makes a system capacity estimation decision process.

[0028] Step B02: Based on the power supply-SOP topology and power supply-TS topology obtained above, group power supplies connected to the same SOP / TS into one category; take the union of the operating capacity constraints of power supplies of the same category, and then take the intersection of the operating capacity constraints of the SOPs / TSs connected to the same category of power supplies:

[0029] {P SOPcap,m Q SOPcap,m}=({P DG,c Q DG,c}∪{P Fe,d Q Fe,d}∪{…})∩{P sop,m Q sop,m}

[0030] {P CAP,TS Q CAP,TS}=({P DG,e Q DG,e}∪{P Fe,f Q Fe,f}∪{…})∩{P TS,n Q TS,n}

[0031] In the formula, P SOPcap,m Q SOPcap,m and P CAP,TS Q CAP,TS These represent the operating capacities of the m-th SOP port and TS port, respectively; P DG,c P DG,e Q DG,c Q DG,e and P Fe,d Q Fe,d P Fe,f Q Fe,f For the remaining operating capacity of distributed power sources and upstream feeders connected to SOP / TS; P SOP,m Q SOP,m and P TS,n Q TS,n These are the respective operating capacities of the two entities.

[0032] Step B03: Combine the SOP, TS, and existing power points within the power loss area to obtain the total system fault recovery capacity.

[0033] {P sys Q sys}={P CAP,TS Q CAP,TS}U{P SOPcap,1 Q SOPcap,1}

[0034] U{…}U{P SOPcap,n Q SOPcap,n}

[0035] P sys and Q sys is the total capacity of the system failure recovery of the outage area.

[0036] Further, in the step C, the load predicted power value is divided by the estimated capacity of each switch to make a one-stage system power adjustment, and the SOP capacity operating position is determined according to the load power factor angle, which specifically includes the following steps:

[0037] Step C01: The one-stage system power adjustment should be based on the power supply output and load equality in the failure recovery process:

[0038]

[0039] P DG,i and Q DG,i are the distributed power capacity in the non-failure outage area; ∑P loadi and ∑Q loadi are the actual active / reactive power of the restored load node; P loadj and Q loadj are the load predicted power of the next to be restored node j; is the load power factor angle.

[0040] Step C02: The load predicted power is divided by the estimated capacity of each switch according to step B02.

[0041] Further, in the step D, it is judged whether the voltage at the end of the low-voltage distribution network feeder is out of limit, and the two-stage system power adjustment is made according to the voltage out of limit, which specifically includes the following steps:

[0042] Step D01: The voltage expression of the low-voltage distribution network feeder is calculated:

[0043]

[0044] P is the voltage at the head of the feeder n, ∑P is the voltage at the bus PCC i , whose phase is 0 by default; R i +jX i is the line impedance, P sop and Q sop are the sum of the active / reactive power transmitted by the SOP connected to the non-failure outage area, R li and Q li are the actual power values of the load.

[0045] Step D02: The two-stage adjustment amount of the active / reactive power of the SOP is calculated according to the voltage out of limit:

[0046]

[0047] where ΔP sop , ΔQ sop is the sum of all SOP power adjustment amount in the area; V Pol is the out-of-limit voltage value, V Pimax and V Pimin are the upper and lower voltage limits.

[0048] Step D03: SOP power two-stage adjustment can be achieved by different active and reactive power adjustment amount combination to achieve the target, this patent gives the adjustment scheme with the minimum apparent power of SOP two-stage adjustment as the target:

[0049]

[0050] where, T is the constant on the right side of the equation in step D02, its value is given when the voltage at PCC i goes out of the upper / lower limit, respectively.

[0051] Step D04: According to the SOP individual port apparent power capacity, the SOP two-stage power adjustment amount is divided:

[0052]

[0053] where, S sop1 : S sop2 :…: S sopn =S1:S2:…:S n is the apparent power capacity of each SOP port.

[0054] An electronic device, comprising a memory, a processor, and a computer program stored on the memory and executable on the processor, wherein the processor implements the power distribution network distributed fault recovery method based on the cooperation of flexible soft switches and tie switches.

[0055] A computer readable storage medium having stored thereon computer instructions, which, when executed by a processor, implement the power distribution network distributed fault recovery method based on the cooperation of flexible soft switches and tie switches.

[0056] Advantages

[0057] The power distribution network distributed fault recovery method based on the cooperation of the flexible soft switch and the tie switch is designed, first, the power supply points in the system are set as lower layer agents, the SOP and the TS are set as upper layer agents to realize the power switch load topology search process, the method effectively solves the problems of long centralized fault recovery calculation time and high communication requirements; then, the power supply capacity estimation of the system is considered according to the above power switch load topology, the load recovery level is judged according to the estimated capacity, and the system recovery speed and the load recovery amount are considered. In addition, for the problem that the terminal voltage of the low-voltage distribution network is easy to exceed the limit, the two-stage system power adjustment process is carried out according to the load predicted power and the terminal voltage level of the low-voltage distribution network, so as to complete the distributed fault recovery and ensure the safety of the system recovery process. The application provides a new idea for the distributed fault recovery of the power distribution network based on the flexible interconnection device, and the recovery scheme calculation speed and the load recovery amount are considered at the same time under the premise of ensuring the safe and reliable recovery operation of the system, and the superiority is achieved. BRIEF DESCRIPTION OF DRAWINGS

[0058] Figure 1 is the flow chart of the distributed fault recovery method of the application;

[0059] Figure 2 is the flexible interconnection distribution network simulation system adopted in the embodiment of the application;

[0060] Figure 3 is the power supply switch load topology structure obtained in the embodiment of the application;

[0061] Figure 4 is the power supply estimated capacity and the load recovery amount obtained in the embodiment of the application;

[0062] Figure 5 is the steady-state voltage per unit of the recovery process PCC in the embodiment of the application;

[0063] Figure 6 is the transient voltage waveform of the feeder 104 when the loads 31 and 43 are recovered in the embodiment of the application;

[0064] Figure 7 is the transient voltage waveform of the DC side of SOP2 when the loads 31 and 43 are recovered in the embodiment of the application;

[0065] Figure 8 is the transient frequency waveform of the power failure area when the loads 31 and 43 are recovered in the embodiment of the application.

[0066] Figure 9 is the comparison chart of a plurality of fault schemes in the embodiment of the application DETAILED DESCRIPTION

[0067] With reference to the drawings, the technical solutions in the embodiments of the present application will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all the other embodiments obtained by those skilled in the art without creative work fall within the scope of the present application.

[0068] As shown in the drawings, the present application provides a power distribution network distributed fault recovery method based on the cooperation of flexible soft switches and contact switches, which in practical application specifically includes the following steps: Figure 1

[0069] Step A: Establishing a power supply node, a set of SOP converter nodes connected with the power failure area and a set of TS load nodes connected with the power failure area, performing breadth-first search through the above node sets by applying the Dijkstra algorithm, respectively calculating the shortest distances from each power supply to the SOP converter nodes connected with the power failure area and the shortest distances from each power supply to the TS load nodes connected with the power failure area, determining the TS position according to the optimal TS determination logic to obtain a power supply-switch-load topology;

[0070] Step B: For the obtained power supply-switch-load topology, each lower-level agent power supply point transmits its remaining capacity information to the connected upper-level agent, and the upper-level agent performs a system capacity estimation decision process;

[0071] Step C: Realizing a one-stage system power adjustment according to the obtained system power supply capacity and load predicted power to achieve capacity sharing, and adjusting the SOP operating capacity based on the load power factor angle;

[0072] Step D: Judging whether there is a voltage out-of-limit situation at the connection of the low-voltage distribution network terminal feeder, if there is a voltage out-of-limit, performing a two-stage system power adjustment based on the SOP, obtaining a power adjustment amount by subtracting the out-of-limit voltage value from the voltage limit value, and adjusting the voltage at the PCC to be within the normal operating limit.

[0073] Further, according to the step A, the power supply-switch-load topology is established by the following steps A01 to A03:

[0074] Step A01: Establishing a power supply node set, a set of SOP converter nodes connected with the power failure area and a set of TS nodes connected with the power failure area, respectively:

[0075] V sourse ={v s1 ,…,v si ,…,v sn}

[0076] V sop ={v​d1 ..., v dj ..., v dm}

[0077] V TS = {v t1 ..., v tk ..., v tp}

[0078] where V si is the i-th power node number, n is the number of power; v dj is the j-th SOP converter node number connected with the off region, m is the number of connected converter; v tk is the k-th TS load node number connected with the off region, p is the number of connected TS.

[0079] Step A02: taking the V sourse point set as the starting point, V sop and V TS point set as the end point, taking one of the power points as the starting point, constantly finding the node with the shortest path distance from the starting point in the unmarked points, and marking it, until all nodes are marked, thereby obtaining the distance matrix of V sourse and V sop , V sourse and V TS .

[0080]

[0081] wherein d(v s1 , v d1 ) in the matrix represents the distance between nodes v s1 and v d1 .

[0082] Step A03: after obtaining the above matrix, according to the shortest path principle, the shortest distance of each row of the matrix is the power-SOP topology and the power-TS topology. According to the power-TS topology, the optimal TS closing point is selected. The optimal TS structure determination logic is as follows:

[0083] 1) Preferably, the TS connected only with the power and not with any SOP is selected;

[0084] 2) If the power connected with the TS is connected with the SOP, for the multi-port SOP, the TS connected with the SOP with more ports is selected;

[0085] 3) In the case of the same number of SOP ports, the region with the highest power blocking degree is selected to be supplied by the TS.

[0086] Further, in the step B, the source capacity estimation method considering the power-switch-load topology is designed.

[0087] Step B01: After obtaining the aforementioned topology, each lower-level agent power point transmits its remaining capacity information to the connected upper-level agent, which then performs the system capacity prediction decision-making process.

[0088] Step B02: Based on the power supply-SOP topology and power supply-TS topology obtained above, group power supplies connected to the same SOP / TS into one category; take the union of the operating capacity constraints of power supplies of the same category, and then take the intersection of the operating capacity constraints of the SOPs / TSs connected to the same category of power supplies:

[0089] {P SOPcap,m Q SOPcap,m}=({P DG,c Q DG,c}∪{P Fe,d Q Fe,d}∪{…})∩{P sop,m Q sop,m}

[0090] {P CAP,TS Q CAP,TS}=({P DG,e Q DG,e}∪{P Fe,f Q Fe,f}∪{…})∩{P TS,n Q TS,n}

[0091] In the formula, P SOPcap,m Q SOPcap,m and P CAP,TS Q CAP,TS These represent the operating capacities of the m-th SOP port and TS port, respectively; P DG,c P DG,e Q DG,c Q DG,e and P Fe,d Q Fe,d P Fe,f Q Fe,f For the remaining operating capacity of distributed power sources and upstream feeders connected to SOP / TS; P SOP,m Q SOP,m and P TS,n Q TS,n These are the respective operating capacities of the two entities.

[0092] Step B03: Combine the SOP, TS, and existing power points within the power loss area to obtain the total system fault recovery capacity.

[0093] {P sys Q sys}={P CAP,TS Q CAP,TS}U{PSOPcap,1 ,Q SOPcap,1}U{…}U{P SOPcap,n ,Q SOPcap,n}

[0094] P sys and Q sys are the total power capacity of the non-faulted de-energized area.

[0095] Further, in the step C, the load predicted power value is divided by the estimated capacity of each switch to make a one-stage system power adjustment, and the SOP capacity operating position is determined according to the load power factor angle, which specifically includes the following steps:

[0096] Step C01: The one-stage system power adjustment should be based on the power supply output and load equation in the fault recovery process:

[0097]

[0098] P DG,i and Q DG,i are the distributed power capacity in the non-faulted de-energized area; ∑P loadi and ∑Q loadi are the actual active / reactive power of the restored load nodes; P loadj and Q loadj are the load predicted power of the next to be restored node j; is the load power factor angle.

[0099] Step C02: The load predicted power is divided by the estimated capacity of each switch according to step B02.

[0100] Further, in the step D, it is judged whether the voltage at the end of the low-voltage distribution network feeder is out of limit, and the two-stage system power adjustment is made according to the voltage out of limit, which specifically includes the following steps:

[0101] Step D01: The voltage expression of the low-voltage distribution network feeder end is calculated:

[0102]

[0103] P is the voltage at the head of the feeder n, is the voltage at the bus PCC i , whose phase is 0 by default; R i +jX i is the line impedance, P sop and Q sop are the sum of the active / reactive power transmitted by the SOP connected to the non-faulted de-energized area, R li and Q li are the actual power values of the load.

[0104] Step D02: Calculate the two-stage adjustment of active / reactive power of SOP according to the voltage out-of-limit amount:

[0105]

[0106] wherein ΔP sop , ΔQ sop is the sum of all power adjustment amounts of SOP in the region; V Pol is the out-of-limit voltage value, V Pimax and V Pimin are the upper and lower limit values of voltage.

[0107] Step D03: The two-stage adjustment of SOP power can be achieved by combining different active and reactive power adjustment amounts, and the adjustment scheme is given by taking the minimum apparent power of the two-stage adjustment of SOP as the target:

[0108]

[0109] wherein T is a constant on the right side of the equation in step D02, and the value is given when the voltage at the PCC i exceeds the upper limit or is below the lower limit, respectively.

[0110] Step D04: Divide the two-stage power adjustment amount of each SOP according to the apparent power capacity of each port of SOP:

[0111]

[0112] wherein S sop1 : S sop2 :…: S sopn = S1: S2:…: S n is the apparent power capacity of each port of SOP.

[0113] The above-mentioned distributed fault recovery scheme is applied to the actual situation, and the power supply recovery simulation system of the 69-node flexible interconnected low-voltage distribution network is shown in Figure 2 The flexible interconnected simulation system is composed of four parts, wherein the power supply area 1 and the power supply area 2, the power supply area 3 are interconnected by the tie switches TS1, TS2, the power supply area 3 and the power supply area 4 are interconnected by the tie switch TS3; the power supply area 1 and the power supply area 3 are interconnected by the two-port flexible interconnection device SOP1 (nodes 63, 64), and the power supply areas 2, 3 and 4 are connected by the three-port flexible interconnection device SOP2 (nodes 65, 66, 67). The white block is the distributed power node, and the load is equivalent to the black circular node. According to the distributed fault recovery method of the distribution network based on the cooperation of the flexible soft switch and the tie switch, the effectiveness and superiority of the method are verified.

[0114] corresponding to Figure 2, it is assumed that feeder 103 fails, supply area 3 loses contact with the upper transformer, and the load in area 3 loses power and needs to be restored. At the time of the failure, the distributed power supply 44 exits operation due to low voltage, and at this time, the available power supply and capacity after the failure are shown in Table C1 in Appendix C. The capacity of the flexible interconnection devices SOP1 and SOP2 connected to the failure area is 300 kVA, and the active power capacity and reactive power capacity of the area interconnection switches TS1, TS2, and TS3 are 350 kW and 120 kVar, respectively. Figure 3 For the power supply-switch-load topology under the distributed fault restoration method of the present patent, the power supply-switch-load topology structure obtained by the method is shown in FIG. 2. Figure 3 For the power supply-switch-load topology structure obtained by the method mentioned in the present patent, on the basis of all power supply points in the system, TS3 is selected as the single traditional transfer point of the outage area according to the TS selection logic, and three supply areas are restored to the non-failure outage area by SOP1, SOP2, and TS3. Figure 4 For the power supply estimated capacity and load restoration amount under the method of the present patent, the horizontal axis represents active power, in units of kW, and the vertical axis represents reactive power, in units of kvar. From Figure 4 It can be seen that the power supply-switch-load topology structure obtained by the method mentioned in the present patent can support the restoration of loads 28-35, 38-41, and 43, and the load restoration amount is about 83.06%. Figure 5 For the steady-state voltage per unit of PCC at feeder 104 in the fault restoration process under the method of the present patent, the horizontal axis represents the sequentially restored load node number, and the vertical axis represents the voltage per unit. From Figure 5 It can be seen that, due to the distributed fault restoration characteristics, the voltage of loads 43 and 31 is 1.071 p.u. and 0.918 p.u. respectively after the first power adjustment in the restoration process, which exceeds the upper / lower limit of the system voltage; after the second power adjustment based on the SOP, the voltage is adjusted to 1.050 p.u. and 0.952 p.u., and the system successfully operates within the safety limit, ensuring the safe operation of the outage area in the fault restoration process. Figure 6 For the transient voltage waveform of feeder 104 in the restoration process of loads 31 and 43, the horizontal axis represents the restoration period, and the vertical axis represents the voltage per unit. From Figure 6 It can be seen that, in the restoration process, the voltage of feeder 104 of load 43 is smoothly increased from 1.033 to 1.071 after the first power adjustment by the SOP, and is smoothly decreased from 1.071 to 1.049 after the second power adjustment by the SOP; in the restoration process, the voltage of feeder 104 of load 31 is smoothly decreased from 0.957 to 0.918 after the first power adjustment by the SOP, and is smoothly increased from 0.918 to 0.952 after the second power adjustment by the SOP; the voltage transient process of both restoration processes is good, and basically no fluctuations occur. Figure 7The SOP2 DC side transient voltage waveform during the restoration of loads 31 and 43 is shown in FIG. 6, where the abscissa represents the restoration period, and the ordinate represents the voltage, in V. As shown in FIG. 6, Figure 7 It can be seen that the maximum points of SOP primary power adjustment transient voltage fluctuation during the restoration of loads 43 and 31 are 753 V and 782 V, respectively, and the maximum points of SOP secondary power adjustment transient voltage fluctuation are 846 V and 760 V, respectively, and the DC side transient fluctuation is within the range of 0.9 p.u. to 1.1 p.u. Figure 8 The transient frequency waveform of the loss of power area during the restoration of loads 31 and 43 is shown in FIG. 7, where the abscissa represents the restoration period, and the ordinate represents the frequency, in Hz. As shown in FIG. 7, Figure 8 It can be seen that the maximum points of SOP primary power adjustment transient frequency fluctuation during the restoration of loads 43 and 31 are 50.06 Hz and 49.94 Hz, respectively, and the maximum points of SOP secondary power adjustment transient frequency fluctuation are 49.97 Hz and 50.05 Hz, respectively, and the transient frequency fluctuation is within the range of 49.9 Hz to 50.1 Hz. Figure 9 The comparison of the fault restoration scheme in 5 is shown in FIG. 8. Figure 9 It can be seen that the method 3 considering the distributed fault restoration of SOP and TS in the present patent has a slightly slower restoration scheme calculation speed than the method 1 considering only TS or the method 2 considering only SOP, but has a significant improvement in the load restoration amount; the method 4 does not perform power point capacity estimation, although it has advantages in restoration amount and restoration speed, but has the problem of voltage out-of-limit caused by power overload; the method 5 is a centralized fault restoration scheme, which does not significantly improve the load restoration amount, but slows down the restoration scheme calculation speed, and the number of nodes participating in the calculation is much higher than that of the distributed fault restoration, and the simple second-order cone optimization model needs more than 5s to solve. In summary, the method 3 proposed in the present patent takes into account the load restoration amount, system safety and restoration scheme calculation speed, and has advantages.

[0115] The power distribution network distributed fault recovery method based on the cooperation of the flexible soft switch and the tie switch comprises the following steps: first, a power source-switch-load topology search method considering the SOP and the TS is established, the Dijkstra algorithm is applied to perform a breadth-first search to obtain the shortest distance from each power source point to the switch, and the TS position is determined according to the optimal TS selection logic, and the load is connected to the recovery topology to form a power source-switch-load topology; then, the power source-switch-load topology is used to realize system power capacity estimation, and the load recovery level is determined according to the estimated power capacity; then, one-stage system power adjustment is performed based on the estimated system power capacity, the SOP port power instruction is modified according to the load predicted power, and the SOP operation capacity is adjusted according to the load power factor angle; finally, it is judged whether the voltage of the low-voltage distribution network terminal feeder is out of limit, and if the voltage is out of limit, two-stage system power adjustment considering the SOP is performed to adjust the voltage at the PCC to be within the system safe operation limit. The method effectively solves the problems of long calculation time and weak communication ability of the centralized fault recovery, and solves the problems of insufficient power capacity and voltage out of limit in the load recovery process, so that the system can be safely and reliably recovered while meeting the maximum load recovery amount. The method takes into account the system recovery speed and the load recovery amount under the premise of ensuring the safety and reliability of the system recovery process, and has economy and superiority.

[0116] In the description of the present specification, the description of the terms "one embodiment", "example", "specific example" and the like means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In the present specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0117] The basic principles, main features and advantages of the present application are shown and described above. It should be understood by those skilled in the art that the present application is not limited by the above embodiments, and the above embodiments and descriptions in the specification are only illustrative of the principles of the present application. Without departing from the spirit and scope of the present application, various changes and improvements can be made to the present application, and these changes and improvements all fall within the scope of the claimed present application.

Claims

1. A power distribution network distributed fault recovery method based on the cooperation of flexible soft switches and tie switches, characterized in that, Comprise: Step A: Establishing power supply nodes, a set of SOP converter nodes connected with the power loss area and a set of TS load nodes connected with the power loss area, applying Dijkstra algorithm through the above node sets to conduct breadth-first search, respectively calculating the shortest distances from each power supply to the SOP converter nodes connected with the power loss area and the shortest distances from each power supply to the TS load nodes connected with the power loss area, determining TS positions according to optimal TS determination logic to obtain power supply-switch-load topology; Step B: For the obtained power supply-switch-load topology, each lower-level agent power supply point transmits its own residual capacity information to the connected upper-level agent, and the upper-level agent conducts system capacity estimation decision process; Step C: Realizing one-stage system power adjustment according to the obtained system power supply capacity and load prediction power to achieve capacity sharing, and adjusting SOP operation capacity based on load power factor angle; Step D: Judging whether there is voltage out-of-limit situation at the connection of low-voltage distribution network terminal feeder, if there is voltage out-of-limit, conducting two-stage system power adjustment based on SOP, obtaining power adjustment amount by subtracting the out-of-limit voltage value from the voltage limit value, and adjusting the voltage at PCC to be within the normal operation limit.

2. The power distribution network distributed fault restoration method based on the cooperation of the flexible soft switch and the tie switch according to claim 1, characterized in that, In the step A, the power supply-switch-load topology is established by steps A01 to A03 as follows: Step A01: respectively establishing a set of power supply nodes, a set of SOP converter nodes connected with the power loss area and a set of TS nodes connected with the power loss area: V sourse = {v s1 ,…,v si ,…,v sn} V sop = {v d1 ,…,v dj ,…,v dm} V TS = {v t1 ,…,v tk ,…,v tp} wherein V si is the number of the i-th power node, n is the number of powers; v dj is the number of the j-th SOP converter node connected to the unpowered area, m is the number of connected converters; v tk is the number of the k-th TS load node connected to the unpowered area, p is the number of connected TSs, Step A02: Take one of the power points as the starting point, and find the unmarked point with the shortest path to the starting point. Mark this point and continue this process until all points are marked. Thus, the distance matrix of V sourse , V sop , V TS , V sourse , V sop , V sourse , and V TS is obtained. where d(v s1 ,v d1 ) represents the distance between nodes v s1 and v d1 , Step A03: after obtaining the upper matrix, according to the shortest path principle, taking the shortest distance of each row of the matrix as the power supply-SOP topology and the power supply-TS topology, selecting the optimal TS closing point according to the power supply-TS topology, and determining the optimal TS structure logic: 1) preferentially selecting TS connected with power supply only and not connected with any SOP; 2) if the power supply connected with TS is connected with SOP, for multi-port SOP, selecting TS connected with the SOP with more ports; 3) selecting the area with the highest power blocking degree for power supply through TS under the condition that the number of SOP ports is consistent.

3. The power distribution network distributed fault restoration method based on the cooperation of the flexible soft switch and the tie switch according to claim 1, characterized in that, The source capacity estimation method considering the power supply-switch-load topology in the step B, Step B01: after obtaining the foregoing topology, each lower-level agent power supply point transmits its own residual capacity information to the connected upper-level agent, and the upper-level agent conducts system capacity estimation decision process, Step B02: according to the obtained power supply-SOP topology and power supply-TS topology, the power supplies connected with the same SOP / TS are classified into one class; the operation capacity constraints of the same class of power supplies are taken as the union set, and the operation capacity constraints of the SOP / TS connected with the same class of power supplies are taken as the intersection set: {P SOPcap,m ,Q SOPcap,m}∩{P DG,c ,Q DG,c}∪{P Fe,d ,Q Fe,d} ∪ {...} ) ∩ { P sop,m Q sop,m} {P CAP,TS ,Q CAP,TS}∩{P DG,e ,Q DG,e}∪{P Fe,f ,Q Fe,f} ∪ {...} ) ∩ { P TS,n Q TS,n} In the formula, P SOPcap,m , Q SOPcap,m and P CAP,TS , Q CAP,TS are the running capacities of the mth SOP port and the TS port respectively; P DG,c , P DG,e , Q DG,c , Q DG,e and P Fe,d , Q Fe,d , P Fe,f , Q Fe,f are the remaining running capacities of the distributed power source connected with the SOP / TS and the upper feeder respectively; and P SOP,m , Q SOP,m and P TS,n , Q TS,n are the running capacities of the two respectively. Step B03: taking the union set of SOP, TS and the power supply points existing in the power loss area to obtain the total capacity of system fault recovery: {P sys ,Q sys}={P CAP,TS ,Q CAP,TS}U{P SOPcap,1 ,Q SOPcap,1} U{…}U{P SOPcap,n ,Q SOPcap,n} In the formula, P sys and Q sys is the total capacity of the power failure area system fault recovery.

4. The power distribution network distributed fault restoration method based on the cooperation of the flexible soft switch and the tie switch according to claim 1, characterized in that: According to the estimated capacity of each switch, the load prediction power value is shared, one-stage system power adjustment is made, the SOP capacity operation position is determined according to the load power factor angle, and the specific steps include the following steps: Step C01: one-stage system power adjustment should be based on the equality of power supply output and load in the fault recovery process: where P DG,i and Q DG,i are the distributed generation power capacity in the non-fault de-energized area;∑P loadi and∑Q loadi are the actual active / reactive power of the restored load nodes; P loadj and Q loadj are the load forecast power of the next to be restored node j; is the load power factor angle, Step C02: According to the estimated capacity of each switch in step B02, the load predicted power is divided.

5. The power distribution network distributed fault restoration method based on the cooperation of the flexible soft switch and the tie switch according to claim 1, characterized in that: Determine whether the voltage at the end of the low-voltage distribution network exceeds the limit, and perform two-stage system power adjustment according to the voltage exceeding limit, which includes the following steps: Step D01: Calculate the voltage expression of the end of the low-voltage distribution network: wherein Vn is the feeder n head voltage, Vpcc is the bus PCC i Vn is the feeder n head voltage, i +jX i Z is the line impedance, P sop and Q sop R and Q are the sum of the active / reactive power transmitted by the SOP connected to the non-faulted de-energized zone, li and Q li R and Q are the actual power values of the load, Step D02: Calculate the two-stage adjustment of SOP active / reactive power according to the voltage exceeding limit: where ΔP sop , ΔQ sop is the sum of all SOP power adjustment amounts in the area; V Pol is the out-of-limit voltage value, V Pimax and V Pimin are the upper and lower voltage limit values, Step D03: The two-stage adjustment of SOP power can achieve the target through different combinations of active and reactive power adjustment, and the adjustment scheme is given by taking the minimum SOP two-stage apparent power as the target: where T is a constant on the right side of equation D02, whose value is given at the upper / lower voltage limit at PCC i respectively, at PCC Step D04: According to the SOP port apparent power capacity, divide the SOP two-stage power adjustment: where S sop1 : S sop2 : S sopn : S n is the apparent power capacity of each SOP port.

6. An electronic device comprising a memory, a processor, and a computer program stored on the memory and executable on the processor, characterized in that: The processor executes the program to realize the distributed fault recovery method of the distribution network based on the cooperation of flexible soft switches and tie switches as claimed in any one of claims 1 to 5.

7. A computer readable storage medium having stored thereon computer instructions, characterized in that: The computer instructions are executed by the processor to realize the distributed fault recovery method of the distribution network based on the cooperation of flexible soft switches and tie switches as claimed in any one of claims 1 to 5.

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