CN115000940A - Comprehensive selection method for power distribution network loop closing points - Google Patents

Comprehensive selection method for power distribution network loop closing points Download PDF

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Publication number
CN115000940A
CN115000940A CN202210617131.9A CN202210617131A CN115000940A CN 115000940 A CN115000940 A CN 115000940A CN 202210617131 A CN202210617131 A CN 202210617131A CN 115000940 A CN115000940 A CN 115000940A
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loop closing
area
loop
power supply
station area
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Inventor
李俊林
彭伟梁
林师玄
鲁鹏程
林劝立
张旭
李华生
李绮琳
王泉华
林希
叶一鸣
刘晓
李婧祺
官志涛
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Guangzhou Power Supply Bureau of Guangdong Power Grid Co Ltd
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Guangzhou Power Supply Bureau of Guangdong Power Grid Co Ltd
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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H02J3/007—Arrangements for selectively connecting the load or loads to one or several among a plurality of power lines or power sources
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H02J3/007—Arrangements for selectively connecting the load or loads to one or several among a plurality of power lines or power sources
    • H02J3/0073—Arrangements for selectively connecting the load or loads to one or several among a plurality of power lines or power sources for providing alternative feeding paths between load and source when the main path fails, e.g. transformers, busbars
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H02J3/007—Arrangements for selectively connecting the load or loads to one or several among a plurality of power lines or power sources
    • H02J3/0075—Arrangements for selectively connecting the load or loads to one or several among a plurality of power lines or power sources for providing alternative feeding paths between load and source according to economic or energy efficiency considerations, e.g. economic dispatch
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H02J3/008—Circuit arrangements for ac mains or ac distribution networks involving trading of energy or energy transmission rights
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J2203/00—Indexing scheme relating to details of circuit arrangements for AC mains or AC distribution networks
    • H02J2203/10—Power transmission or distribution systems management focussing at grid-level, e.g. load flow analysis, node profile computation, meshed network optimisation, active network management or spinning reserve management

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  • Power Engineering (AREA)
  • Supply And Distribution Of Alternating Current (AREA)

Abstract

The invention discloses a comprehensive selection method for a power distribution network loop closing point, which comprises the following steps: acquiring parameter information of the power distribution network, and numbering all spare transformer areas; calculating and judging whether the operation working condition of the power distribution network after the closed-loop switching power supply of each standby station area meets the working condition requirement or not according to the parameter information of the power distribution network; calculating and judging whether the voltage phase difference between the nodes of the main power supply area to be maintained and the nodes of each standby power supply area meeting the requirement of the operating condition meets the condition or not; calculating and judging whether each steady-state loop closing current meets the requirements after loop closing; calculating various indexes, and combining the pre-calculated weight of each closed-loop index to obtain a comprehensive index of each standby station area; and selecting the node of the standby station area with the maximum comprehensive index as the optimal ring closing point, and performing actual ring closing conversion power supply operation on the load on the main station area to be maintained and supplied with power by using the ring closing device selected by the standby station area. The invention can comprehensively, accurately and effectively select the optimal ring closing point and improve the safety and the economy of the ring closing operation.

Description

Comprehensive selection method for power distribution network loop closing points
Technical Field
The invention belongs to the technical field of power distribution network loop closing, and particularly relates to a comprehensive selection method for a power distribution network loop closing point.
Background
With the continuous development of economy, the service concept of power supply enterprises is changed, and the power utilization experience of users is more and more emphasized. In order to improve the power supply reliability, the operation proportion of the closed-loop power supply transfer operation of the power distribution network is increased step by step. However, when the conventional loop closing device (only including the loop closing switch) performs the loop closing power conversion operation, a certain loop closing condition (generally, a difference between phase angles of voltages at two sides of a loop is required to be 0-10 °) is required, and a loop closing impact current exists, so that the operation risk is high. In order to improve the safety and reliability of the loop closing operation, the seamless loop closing device is further researched, and the seamless loop closing device is disclosed in the Chinese patent application number: CN202110372138.4 provides a novel seamless ring closing transfer device of low voltage distribution network, can eliminate the impulse current that closes the ring and change the power supply in-process, realizes closing the ring both sides voltage phase angle difference and not having a power failure in the transfer power supply operation between 0 ~ 30, further improves the power supply reliability.
Before the distribution network loop closing operation is carried out, loop closing point selection is required to be carried out. The selection of the loop closing point is an important problem of switching the loop closing of the power distribution network to the power supply operation. When different loop closing points are selected, different loop closing voltage differences generate different loop closing currents, and the power flow distribution of the circuit after loop closing is different, so that the corresponding loop closing power supply switching operation has different economical efficiency and safety. At present, the loop closing point is mostly selected according to the principle of being nearby, if the loop closing point is not properly selected, the current flowing through the loop closing line is too large, safety problems such as tripping of a line protection switch and overload of power supply equipment can be caused, and even great economic loss is caused. And the safety and the economy of the closed-loop power conversion operation can be improved by selecting the good closed-loop point.
Therefore, it is necessary to research a comprehensive ring closing point selection method considering the conventional and potential ring closing scenarios.
Disclosure of Invention
Aiming at the defects of the prior art, the invention aims to provide a comprehensive selection method of a power distribution network loop closing point, which can comprehensively, accurately and effectively select an optimal loop closing point and improve the safety and the economical efficiency of loop closing operation under the condition of considering the loop closing scene of the traditional loop closing device and the seamless loop closing device.
In order to achieve the purpose, the invention provides a comprehensive selection method of a power distribution network loop closing point, which comprises the following steps:
(1) acquiring parameter information of the power distribution network, and numbering all spare transformer areas;
(2) calculating the operation condition of the power distribution network after the closed-loop switching power supply of each standby station area k according to the parameter information of the power distribution network, executing the step (3) if the operation condition meets the requirement of the operation condition, and finishing the verification of the standby station area if the operation condition does not meet the requirement of the operation condition;
(3) calculating voltage phase differences between the nodes of the main power supply area to be maintained and the nodes of each standby power supply area k meeting the requirements of operation conditions according to the parameter information of the power distribution network, if the voltage phase difference is less than 10 degrees, preliminarily considering that a first loop closing device can be selected between the nodes of the main power supply area to be maintained and the nodes of the standby power supply areas, and executing the step (4), wherein the first loop closing device only comprises a loop closing switch; if the voltage phase difference is larger than or equal to 10 degrees and smaller than or equal to 30 degrees, a second loop closing device is selected between a node of a main power supply area to be maintained and a node of the standby power supply area, and the step (5) is executed, wherein the second loop closing device is used for realizing loop closing switching power supply operation with the voltage phase difference of 0-30 degrees; if the voltage phase difference is larger than 30 degrees, finishing the verification of the spare area;
(4) based on the equivalent method and the superposition principle of the Thevenin theory, calculating the steady-state loop closing current flowing through two sides of a first loop closing device on a loop closing line formed by connecting each standby station area k with a main station area to be maintained after loop closing and the steady-state loop closing current flowing through a feeder line of the standby station area and a feeder line of the main station area to be maintained connected with the feeder line of the main station area to be maintained, and selecting the first loop closing device between a node of the main station area to be maintained and a node of the standby station area if each steady-state loop closing current meets the requirement; if the steady-state loop closing currents do not meet the requirements, a second loop closing device is selected between a node of the main power supply area to be maintained and a node of the standby power supply area;
(5) according to the operation condition of the power distribution network after the loop closing of each standby station k to be verified and the type of the adopted loop closing device, respectively calculating a static voltage stability margin index, a wire stripping safety index, a loop closing current safety index and an economic index of each standby station k, and calculating the comprehensive index of each standby station k by combining the weight of the safety index and the economic index of each standby station k calculated in advance through an analytic hierarchy process;
(6) and selecting the node of the standby station area with the maximum comprehensive index as the optimal ring closing point, and performing actual ring closing conversion power supply operation on the load on the main station area to be maintained and supplied with power by using the ring closing device selected by the standby station area.
According to the comprehensive selection method for the power distribution network loop joining point, provided by the invention, all states of a power system, operation conditions, voltage phase difference and steady-state circulation are comprehensively considered, the economic index and the safety index of the loop joining point are considered, and the reliability of loop joining point selection can be effectively improved; meanwhile, the seamless loop closing transfer device and the traditional loop closing transfer device scene are considered, and the method has higher practical value.
In one embodiment, in step (1), the power distribution network parameter information includes a power distribution network structure, a power distribution network operating condition parameter, a transformer parameter, and a load parameter.
In one embodiment, in step (2), the operating condition requirements include that the circuit power flow meets the requirement of the current-carrying capacity after the loop closing transfer power supply and the load carried by the spare area meets the requirement of the main transformer capacity.
In one embodiment, in step (4), if each steady-state loop closing current meets the requirement, the following formula is satisfied:
Figure BDA0003674824580000031
Figure BDA0003674824580000032
Figure BDA0003674824580000033
Figure BDA0003674824580000034
in the formula (I), the compound is shown in the specification,
Figure BDA0003674824580000041
representing the phase voltage of each spare block k;
Figure BDA0003674824580000042
representing the phase voltage of a power supply main platform area to be maintained; z d Indicating that each reserve k contains loop-closing meansLoop closing circuit equivalent impedance; z 0 The equivalent impedance of the external network except the closed loop circuit is subtracted from each spare transformer area k;
Figure BDA0003674824580000045
showing steady-state loop closing currents flowing through the standby station areas k and the power supply main station area to be maintained after loop closing on two sides of a first loop closing device on a loop closing circuit;
Figure BDA0003674824580000046
representing the steady-state loop closing current flowing through the feeder line of each spare station area k before loop closing;
Figure BDA0003674824580000047
representing the steady-state loop closing current flowing through the feeder line of the main power supply station area to be maintained before loop closing;
Figure BDA0003674824580000048
representing the current flowing through the feeder line of the main station area to be maintained after loop closing;
Figure BDA0003674824580000049
representing the current flowing through the feeder line of each spare area k after loop closing; i is k,max 、I 1,max And I k1, Ring, max And correspondingly representing the current-carrying capacity on the feeder line of each spare station area k, the current-carrying capacity on the feeder line of the main station area to be maintained and the current-carrying capacity on the loop closing circuit.
In one embodiment, in step (5), the static voltage stability margin index α of the k node of each spare area is k,VSM Comprises the following steps:
Figure BDA0003674824580000043
in the formula (P) k +P 1 ) Representing the active load of k nodes of each standby platform area after loop closing;
Figure BDA0003674824580000044
active load for representing voltage breakdown point of k node of each spare transformer area。
In one embodiment, in step (5), the wire stripping safety index α of the k node of each spare area is obtained b Comprises the following steps:
when the loop closing conversion power supply site is the connection of the standby switch at the head end of the low-voltage cabinet between the transformer areas or the bus at the head end of the low-voltage cabinet between the transformer areas, the wire stripping safety index alpha of the node of the standby transformer area b Is 1; when the station area is connected with the near point cable in the closed loop switching power supply site, the wire stripping safety index alpha of the node of the standby station area b And determining according to the closed-loop switching power supply site.
In one embodiment, in the step (5), the loop closing current safety index of the k node of each standby station area is calculated according to the type of the loop closing device selected by the standby station area;
when the standby station area k adopts the second loop closing device, the loop closing safety index alpha of the standby station area k,sa Is 1;
when the spare area k adopts the first loop closing device, the loop closing safety index alpha of the spare area k,sa Comprises the following steps:
α k,sa ＝η 1 ·α k1, impact +η 2 ·α k1, Ring
α k1, impact ＝(I k1, rush max -I k1, impact )/I k1, rush max
Figure BDA0003674824580000051
Figure BDA0003674824580000052
In the formula, alpha k1, impact Indicating an impact current margin index of the first loop closing device selected from each standby station area k; alpha is alpha k1, Ring The steady-state current margin index of the first loop closing device selected from each standby station area k is represented; eta 1 、η 2 Weights corresponding to the inrush current margin indicator and the steady-state current margin indicator; i is k1, rush max Represents eachThe standby station area k is connected with the maintenance power supply main station area to form an overcurrent quick-break protection trigger current on a loop closing circuit; i is k1, punching And the maximum effective value of the impact current on a closed loop circuit formed by connecting each standby station area k and the maintenance power supply main station area is represented.
In one embodiment, in step (5), the economic indicator E of each spare area k k Is as follows;
when the standby station area k adopts the first loop closing device, the standby switch at the head end of the low-voltage cabinet between the station areas is connected on the loop closing transfer power supply site, and the economic index of the standby station area
Figure BDA0003674824580000053
For the bus connection of the head end of the low-voltage cabinet between the station areas on the closed-loop power supply conversion site, the economic index of the standby station area
Figure BDA0003674824580000054
For the close-point cable connection between the station areas on the closed-loop power supply transfer site, the economic index of the standby station area
Figure BDA0003674824580000055
When the standby station area k adopts the second loop closing device, the standby switch at the head end of the low-voltage cabinet between the station areas is connected on the loop closing transfer power supply site, and the economic index of the standby station area
Figure BDA0003674824580000056
For the bus connection of the head end of the low-voltage cabinet between the station areas on the closed-loop power supply conversion site, the economic index of the standby station area
Figure BDA0003674824580000061
For the close-to-point cable connection between the station areas on the closed-loop transfer power supply site, the economic index of the standby station area
Figure BDA0003674824580000062
Where ω and γ denote the singles of the first loop-closing device and the back-up switchOperating costs; psi denotes the single operation cost of the second ring closing device and the fitting; λ represents a unit distance price of the cable; v represents the cost of manually laying cables per unit distance; l is k1 The length of a cable which can be laid between each spare station area k and the power supply main station area to be maintained is represented; e represents the cost of manual wire stripping;
Figure BDA0003674824580000064
represents the cost of single operation of manpower; q represents an economic standard value.
In one embodiment, the comprehensive index Z of each spare station area k k Comprises the following steps:
Z k ＝k 1 ·(h 1 ·α k,VSM +h 2 ·α b +h 3 ·α k,sa )+k 2 ·F k
in the formula, the static voltage stability margin index alpha of each spare station area k k,VSM Safety index alpha of wire stripping b Loop closing current safety index alpha k,sa And economic index E k Should meet the maximum-minimum limit, i.e.
Figure BDA0003674824580000063
If not, the comprehensive index of the spare area is 0.
Drawings
Fig. 1 is a schematic flow chart of a method for comprehensively selecting a power distribution network loop closing point according to an embodiment of the present invention;
fig. 2 is a schematic diagram of different 10kV line partitions of the same 110kV substation according to an embodiment of the present invention;
FIG. 3 is a schematic circuit diagram of a loop closing circuit according to an embodiment of the present invention;
FIG. 4 is a simplified equivalent circuit schematic of the loop closing circuit of FIG. 3;
fig. 5 is a flowchart of a method for comprehensively selecting a power distribution network loop closing point according to an embodiment of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
It should be noted that, in the loop closing scene, when the main power supply area needs to be withdrawn from operation (needs to be maintained), the main power supply area and the standby power supply area are connected through the cable and the loop closing device to form a loop closing circuit, and a load on the main power supply area is transferred to the standby power supply area by operating the loop closing device, so that the loop closing and power supply transferring operation is completed.
In order to solve the problem that the traditional loop closing point is mostly selected according to the principle of being nearby, and the safety and the economical efficiency are poor, the invention provides an accurate, comprehensive and effective comprehensive selection method for the loop closing point of the power distribution network aiming at the important problem that the loop closing point is selected by considering the loop closing scene of the traditional loop closing device and the seamless loop closing device, provides a basis for a power dispatcher to carry out the operation of the loop closing of the power distribution network, and effectively improves the safety and the economical efficiency of the loop closing operation.
Fig. 1 is a schematic flow chart of a comprehensive selection method for a power distribution network ring closing point according to an embodiment of the present invention, and as shown in fig. 1, the comprehensive selection method for a power distribution network ring closing point includes:
s10, acquiring information
Specifically, power distribution network parameter information is obtained, the power distribution network parameter information can include information such as a power distribution network structure, power distribution network operation condition parameters, transformer parameters and load parameters, all the standby station areas are numbered simultaneously, the optimal standby station areas are conveniently selected in the follow-up process, and nodes of the optimal standby station areas correspond to optimal ring closing points. For example, it is assumed that the main power supply station zone can be numbered as station zone 1, and each spare station zone k can be numbered as 2, …, G, although other numbering schemes can be adopted, and the embodiment is not limited.
Steps S20 to S60 are performed for all spare sectors (2, …, G):
s20, calculating and judging whether the power distribution network meets the requirements after closed loop switching power supply
Specifically, according to the information obtained in step S10, it is calculated whether the operation condition of the power distribution network after the loop closing transfer power supply of each standby station area k meets the requirement: after loop closing switching power supply, the circuit tide needs to meet the requirement of current-carrying capacity, and the load carried by a spare transformer area needs to meet the requirement of main transformer capacity. If the operation condition meets the requirement of the working condition, turning to step S30; if the spare area does not meet the working condition requirement, judging that the spare area does not allow loop closing, and finishing the verification of the spare area.
S30, calculating and judging whether the phase difference meets the condition
Specifically, according to the information obtained in S10, voltage phase differences between the nodes of the main power supply area to be maintained and the nodes of the standby power supply area meeting the operating condition requirements are calculated, if the voltage phase difference is less than 10 °, it is preliminarily determined that a first loop closing device can be selected between the nodes of the main power supply area to be maintained and the nodes of the standby power supply area, and then the step S40 is performed to further determine, where the first loop closing device only includes a loop closing switch, that is, a conventional loop closing device, and a loop closing switching power supply operation with a voltage phase difference of 0-10 ° can be realized.
If the voltage phase difference is greater than or equal to 10 ° and less than or equal to 30 °, it is determined that a second loop closing device can be selected between the node of the main power supply area to be maintained and the node of the standby power supply area, and then step S50 is performed, where the second loop closing device is a seamless loop closing device known in the art and is used to implement a loop closing switching power supply operation with a voltage phase difference of 0 to 30 °. If the voltage phase difference is larger than 30 degrees, the verification of the spare area is finished.
S40, calculating and judging whether the steady-state current meets the condition
Specifically, according to the information obtained in S10, based on the equivalent method and superposition principle of the davencin theory, the steady-state loop closing currents flowing through both sides of the first loop closing device on the loop closing line formed by connecting each standby station area k with the main station area to be maintained after loop closing and the steady-state loop closing currents flowing through the standby station area feeder line and the main station area feeder line to be maintained connected therewith are calculated, and if each steady-state loop closing current meets the requirement, the conventional loop closing device is selected between the node of the main station area to be maintained and the node of the standby station area; and if the steady-state loop closing currents do not meet the requirements, selecting a seamless loop closing device between the node of the main power supply area to be maintained and the node of the standby power supply area.
S50, calculating various indexes and obtaining the comprehensive index of each spare area
Specifically, according to the operation condition of the power distribution network after the loop closing of each standby station area k to be verified and the type of the adopted loop closing device, the quiescent voltage stability margin index, the wire stripping safety index, the loop closing current safety index and the economic index of each standby station area k are respectively calculated. And then, calculating the weight of the safety and economic indexes of each spare area k by combining with an analytic hierarchy process in advance to obtain the comprehensive index of each spare area k.
And if the static voltage stability margin index, the wire stripping safety index, the loop closing current safety index and the economic index are not satisfied, setting the comprehensive index of the standby station area to be verified to be 0.
Wherein, the static voltage stability margin index of the standby platform area to be verified is defined as: starting from the steady state after the loop closing of the system, gradually approaching a voltage collapse point by increasing the load power carried by a loop closing point to be verified (a node of a standby station area k to be verified), and keeping the distance from the loop closing steady state of the power distribution network system to the voltage collapse point.
The economic index and the safety index adopt different calculation formulas under different loop closing switching power supply field connection schemes. The loop closing power transfer field connection scheme has three types: the type 1, the spare switches of the low-voltage cabinets between the stations are connected, the cost of a loop closing device, the cost of a cable and the cost of manual operation need to be considered in the aspect of economy, and the safety index of loop closing current and the stability margin of static voltage need to be considered in the aspect of safety; type 2, the low-voltage cabinet bus connection between the stations needs to consider the loop closing device cost, the cable cost, the standby switch cost and the manual operation cost in the aspect of economy, and needs to consider the loop closing current safety index and the static voltage stability margin in the aspect of safety; type 3. the stations are connected by near-point cables, in this case, wires need to be stripped and then connected, the cost of a loop closing device, the cost of cables, the cost of a spare switch, the cost of manual operation and the cost of extra wire stripping need to be considered in the aspect of economy, and the safety index of loop closing current, the safety index of wire stripping and the stability margin of static voltage need to be considered in the aspect of safety.
S60, selecting an optimal ring closing point
And selecting the standby station areas k, taking the node of the standby station area with the maximum comprehensive index as the optimal ring closing point, and performing ring closing switching power supply operation on the load on the main station area to be maintained and supplied with power by using the ring closing device selected by the standby station area.
The comprehensive selection method for the power distribution network loop closing point provided by the embodiment comprehensively considers each state, operation condition, voltage phase difference and steady-state loop current of a power system, gives consideration to economic indexes and safety indexes of the loop closing point, and can effectively improve the reliability of loop closing point selection; meanwhile, the seamless loop closing transfer device and the traditional loop closing transfer device scene are considered, and the method has higher practical value.
To more clearly illustrate the invention, reference is made to the following specific examples:
the situation of distribution network loop closing is described by taking contact of different 10kV buses under different 10kV line partitions of the same 110kV transformer substation as an example, a schematic diagram of different 10kV line partitions under the same 110kV transformer substation is shown in fig. 2, a station area 1 is assumed to be a main station area to be maintained, and a certain loop closing line k1(k is 2, …, G) is shown in fig. 3.
In fig. 3, the platform area 1 is to be maintained, the bus k is communicated with the bus 1, and the load 1 carried by the platform area 1 is transferred to the platform area k. In fig. 3, the 0.4kV feeder loop closing switch is a simple expression of the loop closing device. In the context of figure 3, it is shown,
Figure BDA0003674824580000101
phase voltages of a low-voltage bus k and a low-voltage bus 1 are respectively provided;
Figure BDA0003674824580000102
is the initial current on the feeder line k and the feeder line 1;
Figure BDA0003674824580000103
is closed loop steady state current. The equivalent circuit of the closed loop circuit obtained by the thevenin equivalent method is shown in figure 4, wherein,the ring closing point k and the ring closing point 1 correspond to the low-voltage bus k and the low-voltage bus 1, Z d For loop-closing circuit equivalent impedance including loop-closing device, Z 0 To subtract the equivalent impedance of the outer network except the loop closing circuit.
As shown in fig. 5, the present invention relates to a method for comprehensively selecting a power distribution network loop closing point in a loop closing scene in consideration of a combination of a conventional loop closing device and a seamless loop closing device, and the method includes the following steps:
(one) obtaining information
The method comprises the steps of obtaining information such as distribution network structures, equipment states, system operation conditions, equipment parameters such as transformers and the like, load data and the like in an automation system, and determining the serial numbers of all loop closing points to be verified.
Performing steps (two) - (six) for all ring points k (k ═ 2, …, G) to be selected:
(II) calculating and judging whether the power distribution network meets the requirements after closed loop switching power supply
The distribution network operation condition after closed-loop switching power supply needs to meet the following requirements:
firstly, circuit power flow needs to meet the requirement of current-carrying capacity after loop closing and power supply switching;
I ij ≤I ij,max ,i,j∈N E (1)
in the formula, N E A power distribution network node set is obtained; I.C. A ij Representing the current on lines i-j; i is ij,max The current capacity of the line i-j can be determined according to the specification of the cable adopted by the line i-j.
Secondly, the load of the spare area needs to meet the requirement of main transformer capacity.
(P k +P 1 )≤P Main transformer, k (2)
In the formula (P) k +P 1 ) For transferring the load of the background area k, P Main transformer, k Indicating the capacity of the main transformer k.
If the operation condition meets the requirements of the two points, turning to the step (three); if the loop closing point k is not qualified, judging that the loop closing point k does not allow loop closing, and finishing the verification of the loop closing point k.
(III) calculating and judging whether the phase difference meets the condition
Calculating the phase angle difference of the voltages at two sides of the closed loop point k
Figure BDA0003674824580000111
If it is
Figure BDA0003674824580000112
If the loop closing condition is not met, the loop closing point k does not allow loop closing, and the check is finished; if it is
Figure BDA0003674824580000113
The step (IV) is required to be carried out to further judge the adopted device; if it is
Figure BDA0003674824580000114
Judging that a seamless loop closing device is required to be adopted for loop closing at the point, and turning to the step (five).
(IV) calculating and judging whether the steady-state current meets the condition
Based on the equivalent method and the superposition principle of the Thevenin theory, the two stable currents of the two closed-loop feeders are formed by superposing two parts: one part is the initial current of the two feeders before loop closing
Figure BDA0003674824580000115
The other part is steady-state circulation current caused by voltage amplitude and phase angle difference of loop closing points on two sides of the loop closing switch
Figure BDA0003674824580000116
Calculating a steady state circulating current from the Thevenin equivalent circuit shown in FIG. 4
Figure BDA0003674824580000117
Figure BDA0003674824580000118
The steady-state current flowing through the feeder k after loop closing
Figure BDA0003674824580000119
The following formula:
Figure BDA00036748245800001110
the steady-state current flowing through the feed line 1 after loop closing
Figure BDA00036748245800001111
The following formula:
Figure BDA00036748245800001112
if each steady-state current satisfies the condition, the following formula is satisfied:
Figure BDA00036748245800001113
in the formula I k,max 、I 1,max And I k1, Ring, max The current-carrying capacities of the feeder line k, the feeder line 1 and the loop-closing line can be determined according to the specification of the cable adopted in the loop-closing line.
If the steady-state currents meet the conditions, judging that the traditional loop closing device is adopted, and turning to the step (five); and (5) if the steady-state currents do not meet the conditions, judging that a seamless loop closing device is needed, and turning to the step (five).
(V) calculating various indexes and obtaining a ring-closing point comprehensive index value
And (3) adopting an analytic hierarchy process to pre-obtain the weight of each closed-loop safety and economic index. In the sub-indexes of the closed-loop safety, the corresponding weights of the static voltage stability margin index, the wire stripping safety index and the closed-loop current safety index are h 1 、h 2 、h 3 . The corresponding weights of the closed loop safety and the economic index are respectively k 1 、k 2 。
And respectively calculating a static voltage stability margin index, a wire stripping safety index, a loop closing current safety index and an economic index according to the operation condition of the power distribution network and the type of the adopted device. And obtaining the comprehensive index value of the ring closing point to be verified according to the obtained index weight system.
1) Safety feature
Firstly, static voltage stability margin index
The static voltage stability margin index is shown as follows:
Figure BDA0003674824580000121
in the formula, alpha k,VSM The static voltage stability margin value of a loop closing point k is obtained; (P) k +P 1 ) The active load of a loop closing point k after loop closing transfer;
Figure BDA0003674824580000122
and determining the active load of the k voltage collapse point of the loop closing point according to a continuous power flow method, namely tracking the critical point of the power system under the load change by using a continuous method.
Safety index of wire stripping
The wire stripping safety is denoted as α b That is, the probability of no accident of wire stripping, when the field connection scheme is type 1 and type 2, no wire stripping is needed, so that alpha b Is 1; when the field connection scheme is type 3, wire stripping is required, and alpha is required at the moment b Instead of 1, its value is determined according to the field situation.
③ closing loop current safety index
And respectively calculating the safety indexes of the closed loop current according to different device types.
a. Adopts the traditional ring closing device
According to the steady-state loop closing current flowing through each standby station area k after loop closing and connected with the main station area of the power supply to be maintained on the loop closing circuit on the two sides of the first loop closing device
Figure BDA0003674824580000131
Calculating to obtain the maximum effective value I of the impact current k1, punching ：
Figure BDA0003674824580000132
The impact current margin indexes of the traditional loop closing device are as follows:
α k1, impact ＝(I k1, rush max -I k1, punching )/I k1, rush max (9)
In the formula I k1, rush max The overcurrent quick-break protection trigger current on a closed-loop circuit formed by connecting each standby station zone k and the maintenance power supply main station zone can be determined according to a relay protection setting value in engineering.
Taking a larger steady-state current margin of the feeder line, and calculating a steady-state current margin index of the traditional loop closing device:
Figure BDA0003674824580000133
closing ring safety alpha of traditional closing ring device k,sa It can be expressed as a composite value of the inrush current margin index and the steady-state current margin index:
α k,sa ＝η 1 ·α k1, punching +η 2 ·α k1, Ring (11)
In the formula eta 1 、η 2 And weights corresponding to the impact current margin index and the steady-state current margin index are respectively set.
b. By means of seamless ring closing device
Under the condition that a seamless loop closing device is adopted in a loop closing transfer power supply site, no impact current exists in a loop closing line. Seamless ring closing device can ensure to close the ring safety, and it closes the ring safety and is 1, promptly:
α k,sa ＝1 (12)
2) index of economic efficiency
For different loop closing switching power supply field connection schemes, the economic indexes need to be considered respectively.
a. Adopts the traditional ring closing device
For the field connection scheme 1 of closed-loop switching power supply, the economic indexes are as follows:
Figure BDA0003674824580000141
for the field connection scheme 2 of closed-loop switching power supply, the economic indexes are as follows:
Figure BDA0003674824580000142
for the closed-loop power supply transfer field connection scheme 3, the economic indexes are as follows:
Figure BDA0003674824580000143
in the formula, omega and gamma are the single operation cost of the traditional loop closing device and the standby switch respectively; lambda is unit distance unit price of the cable; upsilon is the cost of manually laying cables in unit distance; l is k1 The length of the cable which can be laid between the loop closing point k and the loop closing point 1 is adopted; e is the manual wire stripping cost;
Figure BDA0003674824580000144
the cost of single operation of manpower is high; q is an economic standard value.
b. By means of seamless ring closing device
For the field connection scheme 1 of closed-loop switching power supply, the economic indexes are as follows:
Figure BDA0003674824580000145
for the type 2 of the platform area, the economic indexes are as follows:
Figure BDA0003674824580000146
for the type 3 of the platform area, the economic indexes are as follows:
Figure BDA0003674824580000147
where ψ is the single operation cost of the seamless ring closure device and fittings.
And (3) setting the comprehensive index value of the loop closing point to be 0:
Figure BDA0003674824580000148
in summary, according to the static voltage stability margin index, the wire stripping safety index, the loop closing current safety index, the economic index and the corresponding weights thereof, the loop closing point comprehensive index value is:
Z k ＝k 1 ·(h 1 ·α k,VSM +h 2 ·α b +h 3 ·α k,sa )+k 2 ·F k (20)
(VI) selecting the optimal ring closing point
Selecting all to-be-selected ring closing points, taking the ring closing point with the maximum comprehensive index value as the optimal ring closing point:
max(Z)＝max(Z k ) (21)
it will be understood by those skilled in the art that the foregoing is only a preferred embodiment of the present invention, and is not intended to limit the invention, and that any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the scope of the present invention.

Claims (9)

1. A comprehensive selection method for a power distribution network loop closing point is characterized by comprising the following steps:
(1) acquiring parameter information of the power distribution network, and numbering all spare transformer areas;
(2) calculating the operation condition of the power distribution network after the closed-loop switching power supply of each standby station area k according to the parameter information of the power distribution network, executing the step (3) if the operation condition meets the requirement of the operation condition, and finishing the verification of the standby station area if the operation condition does not meet the requirement of the operation condition;
(3) calculating voltage phase differences between the nodes of the main power supply area to be maintained and the nodes of each standby power supply area k meeting the requirements of operation conditions according to the parameter information of the power distribution network, if the voltage phase difference is less than 10 degrees, preliminarily considering that a first loop closing device can be selected between the nodes of the main power supply area to be maintained and the nodes of the standby power supply areas, and executing the step (4), wherein the first loop closing device only comprises a loop closing switch; if the voltage phase difference is larger than or equal to 10 degrees and smaller than or equal to 30 degrees, a second loop closing device is selected between a node of a main power supply area to be maintained and a node of the standby power supply area, and the step (5) is executed, wherein the second loop closing device is used for realizing loop closing switching power supply operation with the voltage phase difference of 0-30 degrees; if the voltage phase difference is larger than 30 degrees, finishing the verification of the spare area;
(4) based on the equivalent method and the superposition principle of the Thevenin theory, calculating the steady-state loop closing current flowing through two sides of a first loop closing device on a loop closing line formed by connecting each standby station area k with a main station area to be maintained after loop closing and the steady-state loop closing current flowing through a feeder line of the standby station area and a feeder line of the main station area to be maintained connected with the feeder line of the main station area to be maintained, and selecting the first loop closing device between a node of the main station area to be maintained and a node of the standby station area if each steady-state loop closing current meets the requirement; if the steady-state loop closing currents do not meet the requirements, a second loop closing device is selected between a node of the main power supply area to be maintained and a node of the standby power supply area;
(5) according to the operation condition of the power distribution network after the loop closing of each standby station k to be verified and the type of the adopted loop closing device, respectively calculating a static voltage stability margin index, a wire stripping safety index, a loop closing current safety index and an economic index of each standby station k, and calculating the comprehensive index of each standby station k by combining the weight of the safety index and the economic index of each standby station k calculated in advance through an analytic hierarchy process;
(6) and selecting the node of the standby station area with the maximum comprehensive index as the optimal ring closing point, and performing actual ring closing conversion power supply operation on the load on the main station area to be maintained and supplied with power by using the ring closing device selected by the standby station area.
2. The comprehensive selection method for the power distribution network loop closing points according to claim 1, wherein in the step (1), the power distribution network parameter information comprises a power distribution network structure, a power distribution network operation condition parameter, a transformer parameter and a load parameter.
3. The comprehensive selection method for the loop closing points of the power distribution network according to claim 1, wherein in the step (2), the working condition requirements comprise that a circuit power flow meets the requirement of current carrying capacity after loop closing transfer power supply and a load carried by a spare area meets the requirement of main transformer capacity.
4. The comprehensive selection method for the power distribution network loop closing points according to claim 1, wherein in the step (4), if each steady-state loop closing current meets the requirement, the following formula is satisfied:
Figure FDA0003674824570000021
Figure FDA0003674824570000022
Figure FDA0003674824570000023
Figure FDA0003674824570000024
in the formula (I), the compound is shown in the specification,
Figure FDA0003674824570000025
representing the phase voltage of each spare block k;
Figure FDA0003674824570000026
representing the phase voltage of a power supply main platform area to be maintained; z d Representing the equivalent impedance of a loop closing circuit including the loop closing device in each spare station area k; z 0 The equivalent impedance of the external network except the closed loop circuit is subtracted from each spare transformer area k;
Figure FDA0003674824570000027
showing steady-state loop closing currents flowing through the standby station areas k and the power supply main station area to be maintained after loop closing on two sides of a first loop closing device on a loop closing circuit;
Figure FDA0003674824570000028
representing the steady-state loop closing current flowing through the feeder line of each spare station area k before loop closing;
Figure FDA0003674824570000029
representing the steady-state loop closing current flowing through the feeder line of the main power supply station area to be maintained before loop closing;
Figure FDA00036748245700000210
representing the current flowing through the feeder line of the main station area to be maintained after loop closing;
Figure FDA00036748245700000211
representing the current flowing through the feeder line of each spare area k after loop closing; I.C. A k,max 、I 1,max And I k1, Ring, max And correspondingly representing the current-carrying capacity on the feeder line of each spare station area k, the current-carrying capacity on the feeder line of the main station area to be maintained and the current-carrying capacity on the loop closing circuit.
5. The method for comprehensively selecting power distribution network loop closing points according to claim 1, wherein in the step (5), the static voltage stability margin index α of each spare area k node k,VSM Comprises the following steps:
Figure FDA0003674824570000033
wherein (P) k +P 1 ) Representing the active load of k nodes of each standby station area after loop closing;
Figure FDA0003674824570000034
and the active load of the voltage breakdown point of the k node of each spare area is shown.
6. The comprehensive selection method for the loop closing point of the power distribution network according to claim 5, wherein in the step (5), the wire stripping safety index α of the k node of each spare area is b Comprises the following steps:
when the loop closing conversion power supply site is the connection of the standby switch at the head end of the low-voltage cabinet between the transformer areas or the bus at the head end of the low-voltage cabinet between the transformer areas, the wire stripping safety index alpha of the node of the standby transformer area b Is 1; when the station area is connected with the near point cable in the closed loop switching power supply site, the wire stripping safety index alpha of the node of the standby station area b And determining according to the loop closing switching power supply site.
7. The comprehensive selection method for the power distribution network loop closing points according to claim 6, wherein in the step (5), the loop closing current safety index of the k node of each standby station area is calculated according to the type of the loop closing device selected by the standby station area;
when the standby station area k adopts the second loop closing device, the loop closing safety index alpha of the standby station area k,sa Is 1;
when the spare area k adopts the first loop closing device, the loop closing safety index alpha of the spare area k,sa Comprises the following steps:
α k,sa ＝η 1 ·α k1, impact +η 2 ·α k1, Ring
α k1, impact ＝(I k1, rush max -I k1, impact )/I k1, rush max
Figure FDA0003674824570000031
Figure FDA0003674824570000032
In the formula, alpha k1, impact Indicating an impact current margin index of the first loop closing device selected from each standby station area k; alpha is alpha k1, Ring The steady-state current margin index of the first loop closing device selected from each standby station area k is represented; eta 1 、η 2 Weights corresponding to the inrush current margin indicator and the steady-state current margin indicator; i is k1, rush max The overcurrent quick-break protection trigger current on a closed loop circuit formed by connecting each standby station area k and the maintenance power supply main station area is represented; i is k1, impact The maximum effective value of the impact current on a closed loop circuit formed by connecting each spare station area k and the maintenance power supply main station area is shown.
8. The method according to claim 7, wherein in step (5), the economic indicator E of each spare area k is k Is as follows;
when the standby station area k adopts the first loop closing device, the standby switch at the head end of the low-voltage cabinet between the station areas is connected on the loop closing transfer power supply site, and the economic index of the standby station area
Figure FDA0003674824570000041
For the bus connection of the head end of the low-voltage cabinet between the station areas on the closed-loop power supply conversion site, the economic index of the standby station area
Figure FDA0003674824570000042
For the close-point cable connection between the station areas on the closed-loop power supply transfer site, the economic index of the standby station area
Figure FDA0003674824570000043
When the standby station area k adopts the second loop closing device, the station area is low for the loop closing transfer power supply siteThe first end of the press cabinet is connected with the standby switch, so that the economic index of the standby platform area
Figure FDA0003674824570000044
For the bus connection of the head end of the low-voltage cabinet between the transformer substations on the closed-loop power supply transfer site, the economic index of the standby transformer substation
Figure FDA0003674824570000045
For the close-to cable connection between the station areas on the site of closed loop switching power supply, the economic index of the standby station area
Figure FDA0003674824570000046
Wherein ω and γ represent the cost of a single operation of the first loop closing device and the back-up switch; psi denotes the single operation cost of the second ring closing device and the fitting; λ represents a unit distance price of the cable; v represents the cost of manually laying cables per unit distance; l is a radical of an alcohol k1 The length of a cable which can be laid between each standby station area k and the power supply main station area to be maintained is represented; e represents the cost of manual wire stripping;
Figure FDA0003674824570000047
represents the cost of single operation of manpower; q represents an economic standard value.
9. The method according to claim 8, wherein the composite index Z of each spare area k is k Comprises the following steps:
Z k ＝k 1 ·(h 1 ·α k,VSM +h 2 ·α b +h 3 ·α k,sa )+k 2 ·F k
in the formula, the static voltage stability margin index alpha of each spare station zone k k,VSM Safety index alpha of wire stripping b Loop closing current safety index alpha k,sa And economic index E k Should meet the maximum and minimum limits, i.e.
Figure FDA0003674824570000051
If not, the comprehensive index of the spare area is 0.
CN202210617131.9A 2022-06-01 2022-06-01 Comprehensive selection method for power distribution network loop closing points Pending CN115000940A (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN117394369A (en) * 2023-12-11 2024-01-12 四川迪思源科技有限公司 Uninterrupted power supply-to-power supply regulation and control system based on multidimensional data

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN117394369A (en) * 2023-12-11 2024-01-12 四川迪思源科技有限公司 Uninterrupted power supply-to-power supply regulation and control system based on multidimensional data
CN117394369B (en) * 2023-12-11 2024-02-13 四川迪思源科技有限公司 Uninterrupted power supply-to-power supply regulation and control system based on multidimensional data

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