Distributed new energy reactive power control method for petal type power distribution network

Abstract

The invention provides a petal type power distribution network distributed new energy reactive power control method, and belongs to the technical field of power distribution network voltage reactive power automatic adjustment. The method comprises the following steps: when each control cycle arrives, judging a feeder line operation mode of a petal according to the state of each switch in a switch sequence of each petal closed loop design in a power distribution network; based on the feeder operation mode of the petals and the state of each switch, searching the feeder to which each photovoltaic in the power distribution network belongs; and based on the feeder line to which each photovoltaic device belongs, calculating a reactive power set value of the photovoltaic device so as to realize new energy reactive power control of the power distribution network. The petal-type power distribution network distributed new energy reactive power control can be automatically adapted when the operation mode of the petal-type power distribution network changes, and the safety and reliability of the operation of the petal-type power distribution network are improved.

Description

Technical Field

[0001] The invention belongs to the technical field of voltage and reactive power automatic regulation of distribution networks, and in particular relates to a distributed new energy reactive power control method for a petal-shaped distribution network. Background Art

[0002] In recent years, as users have higher and higher requirements for power supply reliability, the power supply pressure of distribution networks has become increasingly prominent. In order to meet certain high power supply reliability requirements, many medium-voltage distribution networks adopt "petal" type wiring and closed-loop operation, equipped with circuit breakers and complete relay protection and automation equipment, which are significantly different from traditional distribution networks in terms of grid structure and equipment configuration. After a petal-type distribution network fails, through the mutual cooperation of relay protection, backup automatic switching, safety and stability systems and other equipment, it can ensure the normal operation of the "petals" on the intact side while achieving the maximum restoration of power supply to the switch station in the "petals" on the power-off side.

[0003] Before and after the petal-shaped distribution network fault isolation and power supply restoration, the grid structure often undergoes significant changes. Therefore, when controlling the voltage of distributed renewable energy in such distribution networks whose operation modes often change, if the distributed renewable energy cannot be automatically matched with the 10kV bus to which it belongs, it will significantly affect the reactive power control effect and even threaten the voltage stability of the grid. Summary of the invention

[0004] The purpose of the present invention is to overcome the shortcomings of the prior art and propose a petal-shaped distribution network distributed renewable energy reactive power control method. The present invention can automatically adapt to various changes in the operation mode of the petal-shaped distribution network and improve the safety and reliability of the distribution network operation.

[0005] The embodiment of the present invention provides a petal-shaped distribution network distributed renewable energy reactive power control method, comprising:

[0006] 1) At the arrival of each control cycle, the feeder operation mode of each petal is determined according to the state of each switch in the switch sequence of each petal ring design in the distribution network;

[0007] 2) searching for the feeder of each photovoltaic in the distribution network based on the feeder operation mode of the petals and the status of each switch;

[0008] 3) Based on the feeder to which each photovoltaic unit belongs, the reactive power setting value of the photovoltaic unit is calculated to achieve reactive power control of new energy sources in the distribution network.

[0009] In a specific embodiment of the present invention, judging the feeder operation mode of each petal according to the state of each switch in the switch sequence of each petal ring design in the distribution network includes:

[0010] Denote the two feeders of any petal \(f\) in the distribution network as the closed-loop feeder 1 and the closed-loop feeder 2, where \(f\) is the petal number, \(f = 1,\ldots,F\), and \(F\) is the total number of petals in the distribution network;

[0011] Obtain the status of each switch in the switch sequence of petal \(f\) and denote it as \(Kcb\_f\_i\), \(i = 1,\ldots,Kf\). Among them, if the switch is in the closed position, the status value of the switch is 1, and if the switch is in the open position, the status value of the switch is 0. \(Kf\) is the total number of switches in the switch sequence of petal \(f\);

[0012] Calculate the sum of all switch statuses in the switch sequence of petal \(f\) and denote it as \(Kcb\_f\_all\). The expression is as follows:

[0013]

[0014] Judgment:

[0015] If \(Kcb\_f\_all = Kf\), then the two feeders of petal \(f\) are in closed-loop operation. Set the closed-loop operation flag of petal \(f\) to 1, and specify any one of the closed-loop feeders of petal \(f\) as the representative feeder of this petal;

[0016] If \(Kcb\_f\_all < Kf\), then the two feeders of petal \(f\) are in open-loop operation. Set the closed-loop operation flag of petal \(f\) to 0.

[0017] In a specific embodiment of the present invention, the search for the feeder to which each photovoltaic in the distribution network belongs includes:

[0018] 2-1) Initialize the feeder number to which each photovoltaic in the distribution network belongs to 0;

[0019] 2-2) Set the traversal flag of each photovoltaic with a feeder number of 0 in the distribution network to 0;

[0020] Set the traversal flag of each switch in the distribution network to 0;

[0021] Set the traversal flag of each switch station bus in the distribution network to 0;

[0022] Set the traversal flag of each line in the distribution network to 0;

[0023] Set the traversal flag of each connection endpoint in the distribution network to -1;

[0024] 2-3) Judgment:

[0025] If there is an un-searched petal in the distribution network and this petal is in closed-loop operation, then select the representative feeder of this petal as the current feeder, and then enter step 2-4);

[0026] If there is an unsearched petal in the distribution network and the petal is in an open-loop operation state, the closed-loop feeder 1 of the petal is selected as the current feeder, and then step 2-4 is entered;

[0027] If there is a petal that has been searched in the distribution network, the petal is in an open-loop operation state, and the closed-loop feeder 1 of the petal has been searched but the closed-loop feeder 2 has not been searched, then the closed-loop feeder 2 of the petal is selected as the current feeder, and then step 2-4) is entered;

[0028] Otherwise, the feeder belonging to each PV in the distribution network has been searched;

[0029] 2-4) Judgment:

[0030] If the outgoing line switch of the current feeder is in the open position, the current feeder search is completed and the process returns to step 2-3);

[0031] If the outgoing line switch of the current feeder is in the closed position, the traversal flags of the two connection endpoints of the outgoing line switch are set to 0, the traversal flag of the outgoing line switch is set to 1, and then the process goes to step 2-5);

[0032] 2-5) Search all connection endpoints of the distribution network in order, wherein the first connection endpoint with a traversal flag of 0 is numbered as d, the traversal flag of the connection endpoint is set to 1, and then proceed to step 2-6); if no connection endpoint with a traversal flag of 0 is found after all connection endpoints are traversed, the current feeder search is completed, and return to step 2-3);

[0033] 2-6) Searching for each line in the distribution network whose traversal flag is 0, wherein: if one of the connection endpoints of the line is numbered d, the traversal flag of the other connection endpoint of the line is set to 0, and the traversal flag of the line is set to 1;

[0034] Search each switch in the distribution network whose traversal flag is 0, wherein: if one of the connection endpoints of the switch is numbered d and the operating state of the switch is 1, the traversal flag of the other connection endpoint of the switch is set to 0 and the traversal flag of the switch is set to 1; if one of the connection endpoints of the switch is numbered d and the operating state of the switch is 0, the traversal flag of the switch is set to 1;

[0035] Search for each switch station bus with a traversal flag of 0 in the distribution network, wherein: if the connection endpoint number of the switch station bus is d, the traversal flag of the switch station bus is set to 1;

[0036] Search for each photovoltaic power plant with a traversal flag of 0 in the distribution network, where: if the connection endpoint number of the photovoltaic power plant is d, the traversal flag of the photovoltaic power plant is set to 1, and the feeder number of the photovoltaic power plant is set to the current feeder number;

[0037] Then return to step 2-5).

[0038] In a specific embodiment of the present invention, the step of calculating the reactive power setting value of the photovoltaic system based on the feeder to which each photovoltaic system belongs includes:

[0039] 3-1) Obtaining reactive power target value of each feeder in the distribution network;

[0040] 3-2) Traverse each petal, where:

[0041] If the feeder of the petal is in open-loop operation, then traverse each feeder of the petal, find all photovoltaics whose feeder number is the feeder number, and form a subordinate photovoltaic sequence of the feeder; if the feeder of the petal is in closed-loop operation, then find all photovoltaics whose feeder number is the representative feeder number of the petal, form a subordinate photovoltaic sequence of the representative feeder, and correct the reactive power target value of the representative feeder to the sum of the reactive power target values ​​of the closed-loop feeder 1 and the closed-loop feeder 2 of the petal;

[0042] 3-3) for the feeder that forms a subordinate photovoltaic sequence through step 3-2), calculating the reactive power setting value and reactive power limit value of each photovoltaic in the subordinate photovoltaic sequence of the feeder;

[0043] The number of any feeder forming a subordinate photovoltaic sequence is recorded as n, and the active value of each photovoltaic in the subordinate photovoltaic sequence is recorded as Ppv_i, i=1,…,PVn, PVn is the total number of photovoltaics in the subordinate photovoltaic sequence of feeder n; the reactive target value of the feeder is recorded as Qset_n;

[0044] The reactive power setting value of each photovoltaic is calculated and recorded as Qset_pv_i, and the expression is as follows:

[0045]

[0046] The reactive power limit Qpv_max_i of each photovoltaic is calculated according to the power factor limit COSpv_i of each photovoltaic. The expression is as follows:

[0047]

[0048] 3-4) Based on the result of step 3-3), the reactive power setting value of each photovoltaic is corrected:

[0049] If Qpv_max_i≤Qpv_set_i, set Qpv_set_i=Qpv_max_i;

[0050] If Qpv_set_i≤(-1)*Qpv_max_i, set Qpv_set_i=(-1)*Qpv_max_i;

[0051] The corrected reactive power setting value is the final reactive power setting value of the corresponding photovoltaic in the current control cycle.

[0052] The characteristics and effects of the method of the present invention are:

[0053] The present invention establishes a petal-shaped closed-loop operation switch sequence, and can determine the petal-shaped open-closed loop operation mode by simple calculation, which is different from the conventional topological search method and improves the calculation speed. The present invention can automatically adapt to various changes in the operation mode of the petal-shaped distribution network, and improves the safety and reliability of the operation of the petal-shaped distribution network. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] Figure 1 The present invention is an overall flow chart of a method for reactive power control of distributed renewable energy in a petal-shaped distribution network according to an embodiment of the present invention.

[0055] Figure 2 It is a primary wiring diagram of a petal-shaped distribution network according to a specific embodiment of the present invention. DETAILED DESCRIPTION

[0056] The present invention proposes a petal-shaped distribution network distributed renewable energy reactive power control method, which is described in detail below with reference to the accompanying drawings and embodiments.

[0057] This embodiment proposes a petal-shaped distribution network distributed renewable energy reactive power control method, including:

[0058] 1) At the arrival of each control cycle, the feeder operation mode of each petal is determined according to the state of each switch in the switch sequence of each petal ring design in the distribution network;

[0059] 2) searching for the feeder of each photovoltaic in the distribution network based on the feeder operation mode of the petals and the status of each switch;

[0060] 3) Based on the feeder to which each photovoltaic unit belongs, the reactive power setting value of the photovoltaic unit is calculated to achieve reactive power control of new energy sources in the distribution network.

[0061] In a specific implementation of the present invention, the petal-shaped distribution network distributed renewable energy reactive power control method has the following overall process: Figure 1 As shown, the following steps are included:

[0062] 1) At the arrival of each control cycle, the feeder operation mode of each petal in the distribution network is determined according to the state of each switch in the switch sequence of the closed-loop design of each petal.

[0063] In this embodiment, the feeder operation mode of the petals includes closed-loop operation and open-loop operation, wherein the feeder operation mode of any petal f is determined as follows, where f is the petal number, f=1,…,F, and F is the total number of petals in the distribution network:

[0064] Denote the two feeder lines of petal f as loop - closing feeder line 1 and loop - closing feeder line 2. The states of each switch in the switch sequence of petal f obtained from the substation data acquisition system and the distribution network data acquisition system are denoted as Kcb_f_i, where i = 1, …, Kf. Among them, if the switch is in the closed position, the state value of the switch is 1; if the switch is in the open position, the state value of the switch is 0. Kf is the total number of switches in the switch sequence of petal f. Furthermore, calculate the sum of the states of all switches in the switch sequence of petal f, denoted as Kcb_f_all. The expression is as follows:

[0065]

[0066] Determination:

[0067] If Kcb_f_all = Kf, then the two feeder lines of petal f are in loop - closing operation. Set the loop - closing operation flag of petal f to 1, and specify any one of the loop - closing feeder lines of petal f as the representative feeder line of this petal. In a specific embodiment of the present invention, loop - closing feeder line 1 is specified as the representative feeder line of petal f. It should be noted that in this embodiment, if two adjacent petals in the distribution network are in loop - closing operation at the same time, the line between the two petals is not connected.

[0068] If Kcb_f_all < Kf, then the two feeder lines of petal f are in open - loop operation. Set the loop - closing operation flag of petal f to 0.

[0069] 2) Based on the feeder line operation mode of the petals obtained in step 1) and the states of each switch in the distribution network, search for the feeder line to which each photovoltaic in the distribution network belongs.

[0070] In this embodiment, traverse each petal. If the feeder line of the petal is in open - loop operation, then traverse the outgoing switches of each feeder line of this petal to find the photovoltaics connected to the outgoing switches; if the feeder line of the petal is in loop - closing operation, then only find the photovoltaics connected to the outgoing switches of the representative feeder line of this petal. Among them, all the photovoltaics connected to the same outgoing switch belong to the same feeder line. The specific steps are as follows:

[0071] 2 - 1) Initialize the feeder line number to which each photovoltaic in the distribution network belongs to 0.

[0072] 2 - 2) Set the traversal flag of each photovoltaic in the distribution network with the feeder line number 0 to 0.

[0073] Set the traversal flag of each switch in the distribution network to 0.

[0074] Set the traversal flag of each switch - station bus in the distribution network to 0.

[0075] Set the traversal flag of each line in the distribution network to 0.

[0076] Set the traversal flag of each connection endpoint in the distribution network to -1.

[0077] 2-3) Judgment:

[0078] If there is an unsearched petal in the distribution network and the petal is in a closed-loop operation state, the representative feeder of the petal is selected as the current feeder, and then proceed to step 2-4);

[0079] If there is an unsearched petal in the distribution network and the petal is in an open-loop operation state, the closed-loop feeder 1 of the petal is selected as the current feeder, and then step 2-4 is entered;

[0080] If there is a petal that has been searched in the distribution network, the petal is in an open-loop operation state, and the closed-loop feeder 1 of the petal has been searched but the closed-loop feeder 2 has not been searched, then the closed-loop feeder 2 of the petal is selected as the current feeder, and then step 2-4) is entered;

[0081] Otherwise, the feeder of each photovoltaic in the distribution network has been searched, and the process goes to step 3).

[0082] 2-4) Judgment:

[0083] If the outgoing line switch of the current feeder is in the open position, the search for the current feeder is completed and the process returns to step 2-3).

[0084] If the outgoing line switch of the current feeder is in the closed position, the traversal flags of the two connection endpoints of the outgoing line switch are set to 0, the traversal flag of the outgoing line switch is set to 1, and then the process goes to step 2-5).

[0085] 2-5) Search all connection endpoints of the distribution network in sequence, where the first connection endpoint with a traversal flag of 0 is numbered d, the traversal flag of the connection endpoint is set to 1, and then proceed to step 2-6); if no connection endpoint with a traversal flag of 0 is found after all connection endpoints are traversed, the current feeder search is completed and return to step 2-3).

[0086] 2-6) Search for each line in the distribution network whose traversal flag is 0, where: if one connection endpoint of the line is numbered d, the traversal flag of the other connection endpoint of the line is set to 0, and the traversal flag of the line is set to 1.

[0087] Search each switch in the distribution network whose traversal flag is 0, where: if one connection endpoint of the switch is numbered d and the operating state of the switch is 1, the traversal flag of the other connection endpoint of the switch is set to 0 and the traversal flag of the switch is set to 1; if one connection endpoint of the switch is numbered d and the operating state of the switch is 0, the traversal flag of the switch is set to 1.

[0088] Search each switch station bus with a traversal flag of 0 in the distribution network, wherein: if the connection endpoint number of the switch station bus is d, the traversal flag of the switch station bus is set to 1.

[0089] Search each photovoltaic with a traversal flag of 0 in the distribution network, where: if the connection endpoint number of the photovoltaic is d, the traversal flag of the photovoltaic is set to 1, and the feeder number of the photovoltaic is set to the current feeder number.

[0090] Then, return to step 2-5).

[0091] 3) According to the result of step 2), calculate the reactive power setting value of each photovoltaic; the specific steps are as follows:

[0092] 3-1) Obtain the reactive power target value of each feeder in the distribution network from the superior dispatching reactive power voltage control system.

[0093] 3-2) Traverse each petal, where:

[0094] If the feeder of the petal is in open-loop operation, then each feeder of the petal is traversed to find all photovoltaics whose feeder number is the feeder number, forming a subordinate photovoltaic sequence of the feeder; if the feeder of the petal is in closed-loop operation, then only all photovoltaics whose feeder number is the representative feeder number of the petal are found to form a subordinate photovoltaic sequence of the representative feeder, and the reactive power target value of the representative feeder is corrected to the sum of the reactive power target values ​​of the closed-loop feeder 1 and the closed-loop feeder 2 of the petal.

[0095] 3-3) For the feeder that forms a subordinate photovoltaic sequence through step 3-2), the reactive power setting value and reactive power limit value of each photovoltaic in the subordinate photovoltaic sequence of the feeder are calculated.

[0096] In this embodiment, there is no need to calculate the feeder that does not form a subordinate photovoltaic sequence.

[0097] Specifically, the calculation method of the photovoltaic reactive setting value and reactive limit value is as follows:

[0098] In this embodiment, the number of any feeder forming a subordinate photovoltaic sequence is recorded as n, and the active value of each photovoltaic in the subordinate photovoltaic sequence is read from the distribution network data acquisition system as Ppv_i, i=1,…,PVn, PVn is the total number of photovoltaics in the subordinate photovoltaic sequence of feeder n. The reactive target value of the feeder is recorded as Qset_n. The reactive set value of each photovoltaic is calculated as Qset_pv_i, and the expression is as follows:

[0099]

[0100] The reactive power limit Qpv_max_i of each photovoltaic is calculated according to the power factor limit COSpv_i of each photovoltaic. The expression is as follows:

[0101]

[0102] 3-4) Based on the result of step 3-3), the reactive power setting value of each photovoltaic is corrected.

[0103] In this embodiment,

[0104] If Qpv_max_i≤Qpv_set_i, then set Qpv_set_i=Qpv_max_i.

[0105] If Qpv_set_i≤(-1)*Qpv_max_i, then set Qpv_set_i=(-1)*Qpv_max_i.

[0106] The corrected reactive power setting value is the final reactive power setting value of the corresponding photovoltaic in the current control cycle.

[0107] The corrected reactive power setting value Qset_pv_i of the PVn photovoltaic is sent to the corresponding photovoltaic inverter through the distribution network data acquisition system to perform reactive power regulation to achieve corresponding reactive power control.

[0108] Furthermore, the method described in this embodiment is further described below in conjunction with a specific embodiment. In this embodiment, the petal-shaped distribution network distributed renewable energy reactive power control method specifically includes:

[0109] According to Figure 2 The petal-shaped distribution network primary wiring diagram shown in the figure gives each electrical connection terminal a number, and each electrical connection terminal has only one unique number. The switch has 2 connection terminals, the photovoltaic device has 1 connection terminal, and the busbar has 1 connection terminal.

[0110] Establish substation busbar equipment table, switch station busbar equipment table, switch equipment table, photovoltaic equipment table, line equipment table, configure reactive power control related parameters, and mark the connection endpoint number of each device. Specifically:

[0111] In this embodiment, the substation busbar equipment table is shown in Table 1:

[0112] Table 1: Substation busbar equipment table of a specific embodiment of the present invention

[0113] serial number Device Name Connection endpoint number 1 Station A busbar 1 2 Station B bus 2

[0114] The switch station busbar equipment table is shown in Table 2:

[0115] Table 2 Switch station bus equipment table of a specific embodiment of the present invention

[0116]

[0117]

[0118] The photovoltaic equipment table is shown in Table 3:

[0119] Table 3 Photovoltaic equipment of a specific embodiment of the present invention

[0120] serial number Device Name Power factor limit Connection endpoint number 1 Photovoltaic 1 0.9 4 2 Photovoltaic 2 0.9 25 3 Photovoltaic 3 0.9 9 4 Photovoltaic 4 0.9 14 5 Photovoltaic 5 0.9 5 6 Photovoltaic 6 0.9 28

[0121] The line equipment table is shown in Table 4:

[0122] Table 4 Line equipment table of a specific embodiment of the present invention

[0123] serial number Device Name Connection endpoint number 1 Connection endpoint number 2 1 Line 1 2 3 2 Route 2 5 7 3 Line 3 23 24 4 Line 4 8 26 5 Line 5 10 12 6 Line 6 15 17 7 Line 7 19 21 8 Line 8 13 27 8 Line 9 29 30

[0124] The switchgear table is shown in Table 5:

[0125] Table 5: Switchgear table of a specific embodiment of the present invention

[0126]

[0127]

[0128] In this embodiment, a substation feeder table is established based on the outgoing line switch of the substation, and one outgoing line switch corresponds to one feeder.

[0129] In this embodiment, the substation feeder table is shown in Table 6:

[0130] Table 6 Substation feeder table of a specific embodiment of the present invention

[0131] serial number Feeder Name Outlet switch name 1 Feeder A1 A1 2 Feeder A2 A2 3 Feeder B 1 B1 4 Feeder B 2 B2

[0132] The two feeders of the closed-loop design of the substation in this embodiment form a petal, and a switching sequence is established for the closed-loop operation of the two feeders of each petal of the substation. When all switches in the switching sequence are closed, the two feeders of the petal are in closed-loop operation, otherwise they are in open-loop operation.

[0133] In this embodiment, the petal table of the substation is shown in Table 7:

[0134] Table 7: Substation petal table of a specific embodiment of the present invention

[0135] serial number Petal Name Loop feeder 1 Loop feeder 2 Switching sequence for closed-loop operation 1 Substation A petal 1 Feeder A1 Feeder A2 A1, A1, A3, C1, C2, B3, B1, A2 2 Substation B petals 1 Feeder B 1 Feeder B 2 B1, E1, E3, D4, D2, F1, F3, B2

[0136] Working condition 1:

[0137] 1) Determine the feeder operation mode of the petals.

[0138] This embodiment obtains the switch status from the substation data acquisition system and the distribution network data acquisition system, and the switch C4 is in position.

[0139] The remaining switches are all in the closed position. If the switch is in the open position, the switch state value is 0, and if the switch is in the closed position, the switch state value is 1.

[0140] The sum of the state values ​​of the switch sequence of petal 1 of substation A is calculated to be 8, which is equal to the total number of switches in the switch sequence of petal 1 of substation A. It is determined that the two feeders of petal 1 of substation A are in closed-loop operation.

[0141] The sum of the state values ​​of the switch sequence of petal 1 of substation B is calculated to be 8, which is equal to the total number of switches in the switch sequence of petal 1 of substation B. It is determined that the two feeders of petal 1 of substation B are in closed-loop operation.

[0142] 2) Search for the feeder to which each PV belongs.

[0143] Petal 1 of substation A is in closed-loop operation. The petal representing the feeder is selected as feeder A1. The photovoltaic cells connected to the outgoing switch of feeder A1 are photovoltaic 1, photovoltaic 2, and photovoltaic 3.

[0144] Petal 1 of substation B is in closed-loop operation. The petal representing the feeder is selected as feeder B 1. The photovoltaic cells connected to the outgoing switch of feeder B 1 are photovoltaic 4, photovoltaic 5, and photovoltaic 6.

[0145] 3) Calculate each PV reactive power setting value.

[0146] The reactive power target values ​​of feeder A1, feeder A2, feeder B1, and feeder B2 obtained from the superior dispatch reactive power voltage control system are 64kVar, 61kVar, 52kVar, and 47kVar, respectively. The active power values ​​of PV 1, PV 2, PV 3, PV 4, PV 5, and PV 6 obtained from the distribution network data acquisition system are 775kW, 778kW, 756kW, 767kW, 733kW, and 745kW, respectively.

[0147] Substation A petal 1 is in closed-loop operation, and the reactive power target value of its representative feeder is corrected to the sum of the reactive power target values ​​of closed-loop feeder 1 and closed-loop feeder 2, that is, 64+61=125 kVar.

[0148] Petal 1 of substation B is in closed-loop operation, and the reactive power target value of its representative feeder is corrected to the sum of the reactive power target values ​​of closed-loop feeder 1 and closed-loop feeder 2, that is, 52+47=99 kVar.

[0149] Petal 1 of substation A represents the outgoing switch of the feeder (feeder A1), and the photovoltaics connected to them are photovoltaic 1, photovoltaic 2, and photovoltaic 3. The sum of their active power is 775+778+756=2309 (kW), the reactive power setting value of photovoltaic 1 is 125 / 2309*775=42 (kVar), the reactive power setting value of photovoltaic 2 is 125 / 2309*778=42 (kVar), and the reactive power setting value of photovoltaic 3 is 125 / 2309*756=41 (kVar).

[0150] Petal 1 of substation B represents the outgoing switch of the feeder (feeder B 1), and the photovoltaics connected to them are PV 4, PV 5, and PV 6. The sum of their active power is 767+733+745=2245 (kW), the reactive power setting value of PV 4 is 99 / 2245*767=34 (kVar), the reactive power setting value of PV 5 is 99 / 2245*733=32 (kVar), and the reactive power setting value of PV 6 is 99 / 2245*745=33 (kVar).

[0151] The calculation results of working condition 1 in this embodiment are shown in Table 8:

[0152] Table 8 Calculation results of photovoltaic reactive power setting value under working condition 1 in a specific embodiment of the present invention

[0153]

[0154] Finally, the reactive power setting value of each photovoltaic is sent to each photovoltaic for execution through the distribution network data acquisition system, and the reactive power control under this working condition is completed.

[0155] Working condition 2:

[0156] 1) Determine the feeder operation mode of the petals.

[0157] The switch status is obtained from the substation data acquisition system and the distribution network data acquisition system. Switches A1 and A2 are open, and the rest of the switches are closed. The sum of the states of the switch sequence of petal 1 of substation A is calculated to be 6, which is less than the total number of switches in the switch sequence of petal 1 of substation A. It is determined that the two feeders of petal 1 of substation A are in open-loop operation.

[0158] The sum of the states of the switch sequence of petal 1 of substation B is calculated to be 8, which is equal to the total number of switches in the switch sequence of petal 1 of substation B. It is determined that the two feeders of petal 1 of substation B are in closed-loop operation.

[0159] 2) Search for the feeder to which each PV belongs.

[0160] Substation A petal 1 is in open-loop operation, and the outgoing line switches of feeder A1 and feeder A2 have no photovoltaic connected.

[0161] Petal 1 of substation B is in closed-loop operation. The petal representing the feeder is randomly selected as feeder B 1. The photovoltaic cells connected to the outgoing switch of feeder B 1 are photovoltaic 1, photovoltaic 2, photovoltaic 3, photovoltaic 4, photovoltaic 5, and photovoltaic 6.

[0162] 3) Calculate the reactive power setting value of each photovoltaic.

[0163] The reactive power target values ​​of feeder A1, feeder A2, feeder B1, and feeder B2 obtained from the superior dispatch reactive power voltage control system are 0 kVar, 67 kVar, and 55 kVar, respectively. The active power values ​​of PV 1, PV 2, PV 3, PV 4, PV 5, and PV 6 obtained from the distribution network data acquisition system are 554 kW, 438 kW, 476 kW, 495 kW, 462 kW, and 454 kW, respectively.

[0164] Substation B petal 1 is in closed-loop operation, and the reactive power target value of its representative feeder, feeder B1, is corrected to the sum of the reactive power target values ​​of closed-loop feeder 1 and closed-loop feeder 2, that is, 67+55=122 kVar.

[0165] The outgoing line switches of each feeder of petal 1 of substation A have no connected photovoltaic power generation and do not need to be involved in the calculation.

[0166] Petal 1 of substation B represents the photovoltaic cells connected to the outgoing line switch of the feeder line, namely, photovoltaic cell 1, photovoltaic cell 2, photovoltaic cell 3, photovoltaic cell 4, photovoltaic cell 5 and photovoltaic cell 6. The sum of their active power is 554+438+476+495+462+454=2879 (kW), the reactive power setting value of photovoltaic cell 1 is 122 / 2879*554=23 (kVar), the reactive power setting value of photovoltaic cell 2 is 122 / 2879*438=19 (kVar), the reactive power setting value of photovoltaic cell 3 is 122 / 2879*476=20 (kVar), the reactive power setting value of photovoltaic cell 4 is 122 / 2879*495=21 (kVar), the reactive power setting value of photovoltaic cell 5 is 122 / 2879*462=20 (kVar) and the reactive power setting value of photovoltaic cell 6 is 122 / 2879*454=19 (kVar).

[0167] The calculation results of working condition 2 in this embodiment are shown in Table 9:

[0168] Table 9 Calculation results of photovoltaic reactive power setting value under working condition 2 in a specific embodiment of the present invention

[0169]

[0170] Finally, the reactive power setting value of each photovoltaic is sent to each photovoltaic for execution through the distribution network data acquisition system, and the reactive power control under this working condition is completed.

Claims

1. A petal-shaped distribution network distributed renewable energy reactive power control method, characterized in that: Including: 1) When each control period arrives, judge the feeder operation mode of each petal according to the states of the switches in the switch sequence designed for the loop closing of each petal in the distribution network; 2) Based on the feeder operation mode of the petal and the states of the switches, search for the feeder to which each photovoltaic in the distribution network belongs; 3) Based on the feeder to which each photovoltaic belongs, calculate the reactive power set value of the photovoltaic to achieve the reactive power control of new energy in the distribution network.

2. The method according to claim 1, characterized in that The judging the feeder operation mode of the petal according to the states of the switches in the switch sequence designed for the loop closing of each petal in the distribution network includes: Denote the two feeders of any petal f in the distribution network as loop closing feeder 1 and loop closing feeder 2 respectively, where f is the petal number, f = 1, …, F, and F is the total number of petals in the distribution network; Obtain the states of the switches in the switch sequence of petal f, denoted as Kcb_f_i, i = 1, …, Kf, where if the switch is in the closed position, the state value of the switch is 1, and if the switch is in the open position, the state value of the switch is 0, and Kf is the total number of switches in the switch sequence of petal f; Calculate the sum of the states of all switches in the switch sequence of petal f, denoted as Kcb_f_all, and the expression is as follows: Judge: If Kcb_f_all = Kf, the two feeders of petal f are in loop closing operation, set the loop closing operation flag of petal f to 1, and specify any one of the loop closing feeders of petal f as the representative feeder of this petal; If Kcb_f_all < Kf, the two feeders of petal f are in open loop operation, and set the loop closing operation flag of petal f to 0.

3. The method according to claim 2, characterized in that The searching for the feeder to which each photovoltaic in the distribution network belongs includes: 2-1) Initialize the feeder number to which each photovoltaic in the distribution network belongs to 0; 2-2) Set the traversal flag of each photovoltaic with the feeder number 0 in the distribution network to 0; Set the traversal flag of each switch in the distribution network to 0; Set the traversal flag of each switch station bus in the distribution network to 0; Set the traversal flag of each line in the distribution network to 0; Set the traversal flag of each connection end point in the distribution network to -1; 2-3) Judge: If there are un-searched petals in the distribution network and this petal is in loop closing operation state, select the representative feeder of this petal as the current feeder, and then enter step 2-4); If there are un-searched petals in the distribution network and this petal is in open loop operation state, select loop closing feeder 1 of this petal as the current feeder, and then enter step 2-4); If there are searched petals in the distribution network, this petal is in open loop operation state, and loop closing feeder 1 of this petal has been searched but loop closing feeder 2 has not been searched, select loop closing feeder 2 of this petal as the current feeder, and then enter step 2-4); Otherwise, the feeder to which each photovoltaic in the distribution network has been searched; 2-4) Judge: If the outgoing switch of the current feeder is in the open position, the search for the current feeder is completed, and return to step 2-3) again; If the outgoing switch of the current feeder is in the closed position, set the traversal flags of the two connection end points of this outgoing switch to 0, set the traversal flag of the outgoing switch to 1, and then enter step 2-5); 2-5) Search all connection endpoints of the distribution network in order, wherein the first connection endpoint with a traversal flag of 0 is numbered as d, the traversal flag of the connection endpoint is set to 1, and then proceed to step 2-6); if no connection endpoint with a traversal flag of 0 is found after all connection endpoints are traversed, the current feeder search is completed, and return to step 2-3); 2-6) Searching for each line in the distribution network whose traversal flag is 0, wherein: if one of the connection endpoints of the line is numbered d, the traversal flag of the other connection endpoint of the line is set to 0, and the traversal flag of the line is set to 1; Search each switch in the distribution network whose traversal flag is 0, wherein: if one of the connection endpoints of the switch is numbered d and the operating state of the switch is 1, the traversal flag of the other connection endpoint of the switch is set to 0 and the traversal flag of the switch is set to 1; if one of the connection endpoints of the switch is numbered d and the operating state of the switch is 0, the traversal flag of the switch is set to 1; Search for each switch station bus with a traversal flag of 0 in the distribution network, wherein: if the connection endpoint number of the switch station bus is d, the traversal flag of the switch station bus is set to 1; Search for each photovoltaic power plant with a traversal flag of 0 in the distribution network, where: if the connection endpoint number of the photovoltaic power plant is d, the traversal flag of the photovoltaic power plant is set to 1, and the feeder number of the photovoltaic power plant is set to the current feeder number; Then return to step 2-5).

4. The method according to claim 3, characterized in that The step of calculating the reactive power setting value of each photovoltaic system based on the feeder to which each photovoltaic system belongs comprises: 3-1) Obtaining reactive power target value of each feeder in the distribution network; 3-2) Traverse each petal, where: If the feeder of the petal is in open-loop operation, then traverse each feeder of the petal, find all photovoltaics whose feeder number is the feeder number, and form a subordinate photovoltaic sequence of the feeder; if the feeder of the petal is in closed-loop operation, then find all photovoltaics whose feeder number is the representative feeder number of the petal, form a subordinate photovoltaic sequence of the representative feeder, and correct the reactive power target value of the representative feeder to the sum of the reactive power target values ​​of the closed-loop feeder 1 and the closed-loop feeder 2 of the petal; 3-3) for the feeder that forms a subordinate photovoltaic sequence through step 3-2), calculating the reactive power setting value and reactive power limit value of each photovoltaic in the subordinate photovoltaic sequence of the feeder; The number of any feeder forming a subordinate photovoltaic sequence is recorded as n, and the active value of each photovoltaic in the subordinate photovoltaic sequence is recorded as Ppv_i, i=1,…,PVn, PVn is the total number of photovoltaics in the subordinate photovoltaic sequence of feeder n; the reactive target value of the feeder is recorded as Qset_n; The reactive power setting value of each photovoltaic is calculated and recorded as Qset_pv_i, and the expression is as follows: The reactive power limit Qpv_max_i of each photovoltaic is calculated according to the power factor limit COSpv_i of each photovoltaic. The expression is as follows: 3-4) Based on the result of step 3-3), the reactive power setting value of each photovoltaic is corrected: If Qpv_max_i≤Qpv_set_i, set Qpv_set_i=Qpv_max_i; If Qpv_set_i≤(-1)*Qpv_max_i, set Qpv_set_i=(-1)*Qpv_max_i; The corrected reactive power setting value is the final reactive power setting value of the corresponding photovoltaic in the current control cycle.

Images