CN115482124A

CN115482124A - Method, system and terminal for calculating openable capacity of power distribution network based on big data

Info

Publication number: CN115482124A
Application number: CN202211200253.4A
Authority: CN
Inventors: 严俊; 张鹏; 李文龙; 王少芳; 李文琦; 张金平; 武彩凤; 单存知
Original assignee: Tiandaqiushi Electric Power High Technology Co ltd
Current assignee: Tiandaqiushi Electric Power High Technology Co ltd
Priority date: 2022-09-29
Filing date: 2022-09-29
Publication date: 2022-12-16

Abstract

The invention belongs to the technical field of data processing of a power distribution network, and discloses a method, a system and a terminal for calculating the open capacity of the power distribution network based on big data. The method comprises the following steps: comprehensively analyzing the boundary conditions of power supply capacity, power factor, N-1, load rate, maximum load, voltage deviation, harmonic current and short-circuit current of the power distribution network equipment, and constructing a plurality of mathematical models; calculating the maximum access capacity of the distributed power supply of the power distribution network equipment; comprehensively analyzing the upper and lower level constraints of the open capacity of the transformer substation, the circuit and the distribution transformer, and analyzing the open capacity brought by the interruptible load, the distributed power supply and the energy storage access power distribution system which are reduced by the management of the demand side; and based on the openable capacity of the power distribution equipment and the power distribution system under the conventional condition, the openable capacity of the power distribution equipment under the novel power system is calculated. The method provided by the invention solidifies the results to form a corresponding calculation principle, selects a typical area to develop empirical application, and provides support for selection of the openable capacity of the power distribution network.

Description

Method, system and terminal for calculating openable capacity of power distribution network based on big data

Technical Field

The invention belongs to the technical field of data processing of power distribution networks, and particularly relates to a method, a system and a terminal for calculating the openable capacity of a power distribution network based on big data.

Background

The evaluation of the openable capacity of the power distribution network is a hotspot and difficulty of power grid planning and operation and maintenance management. The problems of potential safety hazards, reliable power supply and the like are caused by heavy overload operation of the power distribution network due to excessive load of power distribution network equipment or new energy; the power distribution network equipment is low in load or new energy, light-load operation is easy to cause, the equipment utilization rate is low, and power resources are wasted.

Through the above analysis, the problems and defects of the prior art are as follows:

(1) In the prior art, in the calculation of the maximum receiving capacity of a distributed power supply of power distribution network equipment, the analysis accuracy of the maximum access capacity data of the power supply is low, and technical support cannot be provided for actual operation.

(2) In the prior art, upper and lower level constraints of open capacities of a transformer substation, a medium-voltage line and a distribution transformer cannot be comprehensively analyzed in calculation of open capacities of distribution network equipment and a distribution system, and the open capacity caused by cut interruptible loads, distributed power supplies and energy storage access distribution systems of demand side management is analyzed, so that the accuracy of data obtained by the open capacity of an active distribution network of the power system is low, theoretical support cannot be provided for actual operation, and the equipment utilization rate and the power resource utilization rate are poor.

Disclosure of Invention

In order to overcome the problems in the related art, the disclosed embodiment of the invention provides a method, a system and a terminal for calculating the openable capacity of a large data-based power distribution network. The invention provides a calculation method and empirical analysis of the openable capacity of the power distribution network aiming at the difficulty in calculation of the openable capacity of the power distribution network, provides theoretical support and case application for the calculation method of the openable capacity of the power distribution network, and scientifically guides the ordered access of diversified loads and new energy.

The technical scheme is as follows: a method for calculating the open capacity of a large data distribution network comprises the following steps:

s1, comprehensively analyzing the boundary conditions of power supply capacity, power factor, N-1, load rate, maximum load, voltage deviation, harmonic current and short-circuit current of power distribution network equipment to construct a plurality of mathematical models by taking the maximum access capacity of a distributed power supply as a target; calculating the maximum access capacity of the distributed power supply of the power distribution network equipment;

s2, comprehensively analyzing upper and lower level constraints of open capacities of a transformer substation, a circuit and a distribution transformer based on the constructed mathematical model for calculating the maximum access capacity of the distributed power supply of the power distribution network equipment, and analyzing the open capacity brought by interruptible loads, distributed power supplies and an energy storage access power distribution system which are reduced by demand side management; and a plurality of mathematical models are constructed based on the open capacity of the power distribution equipment and the power distribution system under the conventional condition, and the open capacity of the power distribution network equipment under the novel power system is calculated.

In one embodiment, in step S1, the calculating of the maximum access capacity of the distributed power source of the power distribution network device includes calculating a maximum receiving capacity of the distributed power source by the distribution transformer, where the calculation formula is as follows:

P _pbf -P _pbmin ＝α _pb R _pb δ _pb

in the formula, P _pbf The maximum capacity of the distributed power supply is accessed for 10kV distribution transformer; p _pbmin The load is the minimum load daily load of a 10kV distribution transformer benchmark year; alpha (alpha) ("alpha") _pb The load factor of the distribution transformer is 10kV, and the value is generally less than or equal to 80 percent; r _pb The capacity is 10kV distribution and transformation capacity; delta _pb The power factor of the distribution transformer is 10kV, and is generally 0.9; u shape _pbf Distributing and transforming a low-voltage side bus voltage after the distributed power supply is connected; u shape _pbN To distribute the low side bus voltage.

In one embodiment, in step S1, the calculating of the maximum access capacity of the distributed power source of the power distribution network device further includes calculating a maximum receiving capacity of the line to the distributed power source, where the calculation formula is as follows:

in the formula, P _zxlf The maximum capacity of the 10kV line connected to the distributed power supply; p is _zxlmin The load is the minimum load daily load of a 10kV line benchmark year; u shape _zxlN 10 kilovolts nominal; i is the safe current of a 10kV line; delta _zxl Taking 0.95 as a power factor; alpha is alpha _zxl The maximum load rate of the 10kV line is 50% of the single interconnection line, 66.67% of the two interconnection lines, 75% of the triple interconnection line and 80% of the single radiation line.

U _zxlif And i is the voltage of each 10kV line after the distributed power supply is connected, and is a 10kV line segment which is generally less than or equal to 5.

In one embodiment, in step S1, the calculating the maximum access capacity of the distributed power source of the power distribution network device further includes calculating a maximum receiving capacity of the distributed power source by the high-voltage substation, where a calculation formula is as follows:

P _gbf -P _gbmin ＝α _gb R _gb δ _gb

I _xz ＞I _m

I _xzh ＞I _h

in the formula, P _gbf The maximum capacity of the distributed power supply is accessed to the high-voltage substation; p _zxlmin The minimum annual load daily load is the benchmark annual minimum load of the high-voltage transformer substation; alpha is alpha _gb The maximum load rate under the condition of N-1 is met for the high-voltage transformer substation; delta. For the preparation of a coating _gb Taking 0.98 as the power factor of the high-voltage substation; r _gb Capacity of the high voltage substation; I.C. A _xz Short-circuit current is the system bus; i is _m Is an allowable short circuit current value; u shape _gbf The voltage value is the voltage value of the high-voltage transformer substation after the high-voltage transformer substation is connected; u shape _gbN The nominal voltage value is the nominal voltage value of the high-voltage transformer substation; i is _xzh Is the h harmonic current value; i is _h The h-th harmonic current limit specified for GB/T14549.

In one embodiment, in step S2, comprehensively analyzing upper and lower level constraints of the distribution and transformation open capacity, and analyzing the open capacity brought by the interruptible load, the distributed power sources, and the energy storage access distribution system reduced by the demand side management, includes:

combining the factors of the distributed power supply and the energy storage, the open capacity calculation formula of the distribution transformer is as follows:

in the formula, k _xpb The open capacity of the 10kV distribution transformer is considered; alpha is alpha _pb The maximum load rate of the distribution transformer is 10kV, and the value is generally 80%; r _pb The capacity is 10kV distribution and transformation capacity; delta _pb The power factor of the distribution transformer is 10kV, and is generally 0.9; p _pb The maximum load of the 10kV distribution transformer is existed; p is _pbfc The output of the distributed power supply under the condition of the maximum load of the 10kV distribution transformer is realized; p is _pbc The load capacity is reduced for the energy storage under the condition of maximum load of a 10kV distribution transformer.

In one embodiment, in step S2, comprehensively analyzing upper and lower constraints of the line open capacity, and analyzing the open capacity brought by the interruptible load, the distributed power supply, and the energy storage access power distribution system reduced by the demand side management, includes:

by combining the factors of the distributed power supply and the energy storage, the calculation formula of the open capacity of the line is as follows:

in the formula, k _zxl Is the open capacity of a 10kV line; u shape _zxlN Is the nominal voltage of a 10kV line; i is the safe current of a 10kV line; delta _zxl For power factor, generally 0.95 is taken; alpha is alpha _zxl The maximum load rate of a 10kV line is 50% of a single interconnection line, 66.67% of two interconnection lines, 75% of a triple interconnection line and 80% of a single radiation line; p _zxl The existing maximum load of a 10kV line; p _zxlfc The output of the distributed power supply under the condition of the maximum load of a 10kV line is realized; p is _zxlc The energy storage and load reduction capability is realized under the condition of the maximum load of a 10kV line.

In one embodiment, in step S2, comprehensively analyzing upper and lower constraints of the substation open capacity, and analyzing the open capacity brought by interruptible loads, distributed power sources, and energy storage access distribution systems reduced by demand side management, includes:

by combining the factors of the distributed power supply and the energy storage, the open capacity calculation formula of the transformer substation is as follows:

in the formula, k _gb Opening capacity for the high voltage substation; alpha is alpha _gb The maximum load rate of the high-voltage transformer substation is obtained; delta _gb The power factor of a high-voltage transformer substation is generally 0.98; r _gb Capacity of the high voltage substation; p _gb For transforming high voltageThe station has a maximum load; p is _gbfc The distributed power supply is powered on under the condition of the maximum load of the high-voltage transformer substation; p _gbc The load capacity is reduced for the energy storage under the condition of the maximum load of the high-voltage transformer substation.

In one embodiment, before step S1, the following steps are performed: and analyzing the selection of power factors, N-1, load rate and load of distribution transformers, lines and substations under the conventional condition, constructing a mathematical model, and determining a calculation method of the open capacity of the power distribution network equipment under the conventional condition.

Another object of the present invention is to provide a system for calculating an openable capacity of a large data distribution network, including:

the calculation module of the open capacity of the power distribution network equipment under the conventional condition is used for analyzing the selection of power factors, N-1, load rate and load of distribution transformers, lines and substations under the conventional condition, constructing a mathematical model and determining a calculation method of the open capacity of the power distribution network equipment under the conventional condition;

the power distribution network equipment distributed power supply maximum receiving capacity calculation module is used for comprehensively analyzing the power supply capacity, the power factor, N-1, the load rate, the maximum load, the voltage deviation, the harmonic current and the short-circuit current boundary condition of the power distribution network equipment with the maximum distributed power supply access capacity as a target, and constructing a plurality of mathematical models; calculating the maximum access capacity of the distributed power supply of the power distribution network equipment;

the method comprises the steps that a mathematical model is calculated based on the maximum access capacity of the distributed power supply of the power distribution network equipment and is used for comprehensively analyzing upper and lower level constraints of open capacities of a transformer substation, a circuit and a distribution transformer and analyzing the open capacity brought by interruptible loads, distributed power supplies and an energy storage access power distribution system which are reduced by demand side management; and a plurality of mathematical models are constructed based on the open capacity of the distribution equipment and the distribution system under the conventional condition, and the open capacity of the distribution equipment under the novel power system is calculated.

Another object of the present invention is to provide an information data processing terminal, which is configured to provide a user input interface to implement the method for calculating the openable capacity of the big data based power distribution network when the terminal is executed on an electronic device.

By combining all the technical schemes, the invention has the advantages and positive effects that:

first, aiming at the technical problems existing in the prior art and the difficulty in solving the problems, the technical problems to be solved by the technical scheme of the present invention are closely combined with results, data and the like in the research and development process, and some creative technical effects are brought after the problems are solved. The specific description is as follows:

the invention innovatively provides a method for calculating the maximum access capacity of a distributed power supply of power distribution network equipment, which is used for comprehensively analyzing boundary conditions of power supply capacity, power factor, N-1, load rate, maximum load, voltage deviation, harmonic current, short-circuit current and the like of the power distribution network equipment by taking the maximum access capacity of the distributed power supply as a target to construct a mathematical model and provide the method for calculating the maximum access capacity of the distributed power supply of the power distribution network equipment. The method combines system simulation, reasonably predicts the maximum access capacity of the distributed power supply of the power distribution network equipment, improves the prediction precision, avoids the problems of voltage and current out-of-limit and the like caused by overlarge distributed photovoltaic access, and ensures the safe and stable operation of the power distribution system.

The invention innovatively provides a method for calculating the open capacity of power distribution network equipment and a power distribution system; the method comprises the steps of comprehensively analyzing upper and lower level constraints of open capacities of a transformer substation, a medium-voltage line and a distribution transformer, analyzing the open capacity brought by interruptible loads, distributed power sources and energy storage access power distribution systems which are reduced by demand side management, constructing a mathematical model based on the openable capacities of power distribution equipment and the power distribution systems under conventional conditions, and providing a novel power system-oriented method for calculating the openable capacity of the active power distribution network. The method comprehensively considers the coordination and interaction of flexible resources, reasonably predicts the open capacity of the power distribution network, and scientifically guides the ordered access of diversified loads and new energy; meanwhile, the precision of construction investment of the power distribution network is improved, the waste of system standby capacity is avoided, and the quality and the efficiency of the power distribution system are improved.

Secondly, regarding the technical solution as a whole or from the perspective of products, the technical effects and advantages of the technical solution to be protected by the present invention are specifically described as follows:

according to the method, the influence of large-scale new energy (especially distributed power sources) accessing a power distribution network on the operation characteristics of the power distribution network is combined, the internal relation between the openable capacity of the power distribution network and interval resources, capacity resources, a grid structure, operation constraints, flexible resources and the like is analyzed based on an influence factor analysis method, and results are solidified to form a corresponding calculation principle by combining a mathematical model, a calculation flow and data requirements of the openable capacity of power distribution equipment and a power distribution system, so that the basic level is effectively guided to carry out calculation of the openable capacity of the power distribution network; and a typical area is selected to develop empirical application, and support is provided for selection of the openable capacity of the power distribution network.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present disclosure and, together with the description, serve to explain the principles of the disclosure.

Fig. 1 is a flowchart of a method for calculating an openable capacity based on a big data distribution network according to an embodiment of the present invention;

fig. 2 is a schematic diagram of a calculation method for openable capacity based on a big data distribution network according to an embodiment of the present invention;

fig. 3 is a flowchart of a method for calculating the capacity of a 10kV distribution transformer accessible maximum distributed power supply according to an embodiment of the present invention;

fig. 4 is a flowchart of calculating the capacity of the maximum distributed power source accessible to the 10kV line according to the embodiment of the present invention;

fig. 5 is a flowchart for calculating the maximum distributed power capacity that a high-voltage substation can access according to an embodiment of the present invention;

FIG. 6 is a schematic representation of a typical power output curve of a hydroelectric power plant provided by an embodiment of the present invention;

FIG. 7 is a schematic diagram of an exemplary output curve of a photovoltaic power plant provided by an embodiment of the present invention;

FIG. 8 is a schematic view of a typical output curve of a wind power plant provided by an embodiment of the present invention;

fig. 9 is a schematic diagram of a computing system based on the openable capacity of a big data distribution network according to an embodiment of the present invention;

fig. 10 is a diagram of a distribution transformer variable access distributed photovoltaic simulation system provided by an embodiment of the present invention;

fig. 11 is a diagram of a line-accessible distributed photovoltaic simulation system provided by an embodiment of the present invention;

fig. 12 is a diagram of a substation accessible distributed photovoltaic simulation system provided by an embodiment of the present invention;

in the figure: 1. the power distribution network equipment open capacity calculation module under the conventional condition; 2. the power distribution network equipment distributed power supply maximum receiving capacity calculation module; 3. and a power distribution network equipment open capacity calculation module under the novel power system.

Detailed Description

In order to make the aforementioned objects, features and advantages of the present invention more comprehensible, embodiments accompanying figures are described in detail below. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. This invention may, however, be embodied in many different forms than those specifically described herein, and it will be apparent to those skilled in the art that many more modifications are possible without departing from the spirit and scope of the invention.

1. Illustrative examples are illustrated:

as shown in fig. 1, an embodiment of the present invention provides a method for calculating an open capacity of a large data distribution network, including the following steps:

s101, constructing a mathematical model, and determining a calculation method of the open capacity of the power distribution network equipment under the conventional condition;

analyzing the selection of distribution transformers, power factors of lines and substations, N-1, load rate and load under the conventional condition, constructing a mathematical model, and determining a calculation method of the open capacity of the power distribution network equipment under the conventional condition;

s102, comprehensively analyzing boundary conditions of the power distribution network equipment with the maximum distributed power supply access capacity as a target, and constructing a plurality of mathematical models;

comprehensively analyzing the boundary conditions of power supply capacity, power factor, N-1, load rate, maximum load, voltage deviation, harmonic current and short-circuit current of the power distribution network equipment to construct a plurality of mathematical models by taking the maximum access capacity of the distributed power supply as a target; calculating the maximum access capacity of the distributed power supply of the power distribution network equipment;

and S103, analyzing the reduced open capacity managed by the demand side based on the constructed mathematical model, and calculating the open capacity of the distribution network equipment under the novel power system.

On the basis of the constructed mathematical model for calculating the maximum access capacity of the distributed power supply of the power distribution network equipment, comprehensively analyzing the upper and lower level constraints of the open capacity of the transformer substation, the circuit and the distribution transformer, and analyzing the open capacity brought by the interruptible load, the distributed power supply and the energy storage access power distribution system which are reduced by the demand side management; and a plurality of mathematical models are constructed based on the open capacity of the power distribution equipment and the power distribution system under the conventional condition, and the open capacity of the power distribution network equipment under the novel power system is calculated.

Example 1

The method for calculating the openable capacity of the large data-based power distribution network comprises the following steps:

the embodiment of the invention indicates the improvement direction of the calculation model of the openable capacity of the power distribution network under the novel power system by analyzing the development condition of new energy, the admission capacity of the power distribution network to the new energy and the existing analysis result of the openable capacity of the power distribution network, the calculation method of the openable capacity of the traditional power distribution network and the defects thereof.

Aiming at the large-scale distributed power supply connected to the power distribution network, the influence on the operation characteristic of the power distribution network is improved; according to the power distribution network flow optimization result, the internal relation between the power distribution network openable capacity and interval resources, capacity resources, a grid structure, operation constraints, flexibility resources and the like is analyzed on the basis of the influence factor analysis method, and a theoretical basis is provided for selection of the power distribution network openable access capacity.

Based on the influence factors of the open capacity of the power distribution network, the open capacity calculation method of the line, the distribution transformer access load and the distributed power supply is analyzed respectively, and a corresponding mathematical model, a calculation flow and data requirements are provided. Wherein, the load access mainly analyzes the N-1 passing rate, the heavy overload condition and other constraint conditions; the photovoltaic access mainly analyzes constraint conditions such as voltage deviation, network loss, harmonic waves, three-phase imbalance and the like.

On the basis of a power distribution equipment open capacity calculation method, the current situation of a power distribution network, new energy planning and power grid planning information are analyzed in a comprehensive mode, and a power distribution system open capacity evaluation model is constructed; an evaluation model optimization solving method is provided to obtain the open capacity of the power distribution system and a system operation simulation result; according to the calculation process of the open capacity of the power distribution system, the method for acquiring and integrating the demand data is provided.

The method comprises the steps of calculating data requirements according to the standard of the openable capacity of the carding power distribution network, analyzing and calculating principles from the aspects of the maximum load rate, voltage deviation, harmonic current allowable value and the like of power distribution network equipment, simulating by applying an active power distribution network comprehensive analysis system tool according to related data and principles, and calculating a typical result of the openable capacity of the power distribution network equipment.

The embodiment of the invention selects a typical area, develops the demonstration application on the result and verifies the scientificity, validity and practicability of the result.

The technical solution of the present invention will be further described with reference to the following detailed analysis

Example 2

Analysis of influence factors of open capacity of distribution network

1. Influence of new energy access on power distribution network

The new energy accessed to the power distribution network is generally a distributed power supply, and the distributed power supply generally refers to a small modular, distributed and reliable power generation unit with the power generation power of several kilowatts to tens of megawatts, and the small modular, distributed and reliable power generation unit is arranged near users. Distributed power sources are of many kinds, mainly including: photovoltaic power generation, wind power generation, biomass power generation, micro gas turbines, various energy storage technologies and the like. In addition, the emerging tidal power generation, wave power generation and the like will also become important components of the future distributed power supply.

2. Impact of distributed power access on power distribution network

After a large number of distributed power supplies are connected to a power distribution network, the operation structure of the power distribution network is changed from a traditional single radiation mode to a bidirectional trend, power supply points can reach all nodes of the power distribution network, the scale development of the distributed power supplies is rapid along with policy incentive, the permeability in the power distribution network system is remarkably improved, the random small scale is developed to a large scale, and the influence is brought to the aspects of voltage level, network loss and the like of the power distribution network system.

3. Effect of multiple load access on distribution network

Uncontrollable load, adjustable load, controllable load and newly-developed diversified load influence the power distribution network.

4. Influence of energy storage access on distribution network

The energy storage configuration method and the energy storage charging and discharging have influence on the power distribution network.

5. Factor affecting openable capacity of power distribution network

The existing analysis methods include: analytic hierarchy process, fishbone map analysis.

6. Analysis of influence factors of openable capacity of power distribution network

The influence of a large amount of access of distributed power sources, multi-load and energy storage on the power distribution network is combined, and influence factors of the openable capacity of the power distribution network can be analyzed from the aspects of safety, reliability, cleanness, low carbon, flexibility, high efficiency and open interaction.

7. The embodiment of the invention firstly carries out analysis on the influence of new energy access on the power distribution network, the distributed power supply type is mainly divided into wind power, photovoltaic, biomass, a micro gas turbine and a fuel cell, and the influence of the distributed power supply access on the power distribution network is mainly reflected in the aspects of voltage and reactive power regulation, electric energy quality, relay protection and the like.

And secondly, carrying out analysis on the influence of the access of diversified loads on the power distribution network, wherein the diversified load types are mainly divided into uncontrollable loads, adjustable loads, controllable loads and emerging diversified loads, and the influence of the access of the diversified loads to the power distribution network is mainly reflected in the requirements on optimizing the control of the power grid operation, real-time management of the power quality and flexible and efficient development of demand side management.

Then, the influence of the energy storage access to the power distribution network is analyzed, the energy storage configuration aims mainly include fluctuation stabilization, energy management and power distribution network reliability improvement, the influence of the energy storage access to the power distribution network mainly shows that the influence is in peak regulation and frequency modulation on the power supply side, new energy is consumed, active and reactive power is adjusted on the power distribution network side, overcurrent risk is reduced, peak clipping and valley filling are carried out, the reliability is improved, the power supply problem is solved on the user side, the reliability is improved, and the economy is improved.

And finally, analyzing influence factors of the openable capacity of the power distribution network, dividing the influence factors into four aspects of safety, reliability, cleanness, low carbon, flexibility, high efficiency and open interaction by an analytic hierarchy process, and analyzing specific influence factors by a fishbone diagram analytical method to construct an openable capacity influence factor system of the power distribution network.

(II) the technical scheme of the invention is further described by combining a calculation method of the open capacity of the power distribution network equipment

1. Method for calculating open capacity of power distribution network equipment under conventional condition

Under the conventional condition, the calculation of the open capacity of the power distribution network equipment is mainly divided into the calculation of the open capacity of a 10kV distribution transformer, the calculation of the open capacity of a 10kV line and the calculation of the open capacity of the high-voltage transformer substation three-level power distribution network equipment. Wherein: the open capacity of the 10kV distribution transformer is not more than the open capacity of a 10kV line, and the open capacity of the 10kV line is not more than the open capacity of a high-voltage transformer substation. Factors influencing the open capacity of power distribution network equipment in the conventional situation mainly comprise load rate, power supply capacity, power factor, load and the like.

2. Method for calculating open capacity of 10kV distribution transformer under conventional condition

Under the conventional condition, the 10kV distribution transformer can not carry out heavy load operation, and the maximum load rate of the 10kV distribution transformer can reach 80 percent, so that the calculation formula of the open capacity of the 10kV distribution transformer is as follows:

in the formula, k _pb The open capacity of the distribution transformer is 10 kV; alpha is alpha _pb The maximum load rate of the distribution transformer is 10kV, and the value is generally 80%; r _pb The capacity is 10kV distribution and transformation capacity; delta _pb The power factor of the distribution transformer is 10kV, and is generally 0.9; p _pb The maximum load exists for the 10kV distribution transformer.

3. Method for calculating open capacity of 10kV line under conventional condition

The open capacity calculation formula of the 10kV line under the conventional condition is as follows:

in the formula, k _zxl The open capacity of a 10kV line; u shape _zxlN Is the nominal voltage of the 10kV line; i is the safe current of a 10kV line; delta _zxl For power factor, generally 0.95 is taken; alpha (alpha) ("alpha") _zxl The maximum load rate of a 10kV line is 50% of a single interconnection line, 66.67% of a two interconnection line, 75% of a triple interconnection line and 80% of a single radiation line; p is _zxl The existing maximum load of a 10kV line.

4. Method for calculating open capacity of high-voltage substation under conventional condition

4.1 method for calculating maximum load rate of main transformer of high-voltage transformer substation

(1) Typical contact model of transformer substation

The typical transformer substation contact model is a power supply model formed by combining different transformer substation main transformer configurations and different numbers of interconnected transformer substation seats and connecting transformer substations by using 10kV lines. According to typical power supply mode analysis of a power distribution network of the national power grid company, in the same power supply module, any main transformer of a transformer substation is only in mutual communication with one main transformer of an opposite side station. The contact mode has clear structure, clear transfer, few required lines and high theoretical load rate of equipment under the condition of meeting the requirement of 'N-1'. Thus, the established contact model may be based on such a symmetric contact structure.

In conclusion, on the basis of the symmetrical contact structure, a typical contact model is established by selecting 2-3 main transformers in the substation and a 10kV line for single contact, two contact and three contact.

Meanwhile, the number of the interconnected transformer substation seats selected by the invention is 2-4. The established typical contact model can be extended when there are more substations in the same power block. For example, in the case of ring power supply of N substations, each substation has contact with only two adjacent substations, and can be classified into a typical substation contact model of interconnection of three substations.

In order to simplify the analysis level, two dimensions of the number of interconnected substation seats and the configuration of main substations in a typical transformer substation contact model are combined to form a combined mode of ' transformer substation-main substation ' (m × n) ', wherein the combined mode of ' transformer substation-main substation ' (m × n) comprises six types: 2 × 2, 2 × 3, 3 × 2, 3 × 3, 4 × 2, 4 × 3.

The main transformer load factor of the transformer substation is influenced by the main transformer contact relation in the transformer substation and the main transformer configuration and the transformer substation seat number in the transformer substation contact model. Therefore, for a certain transformer substation combination mode, the ideal load rate of the main transformer of the transformer substation can be calculated as long as the main electrical wiring mode in the transformer substation is determined.

By analyzing the electric main wiring form of the domestic urban transformer substation, the main transformer configuration in the current high-voltage transformer substation is usually 2-3.

The main wiring form of the low-voltage side in the station is described as follows:

when a double-main-transformer configuration is adopted in a high-voltage transformer substation, a single-bus section wiring mode is generally adopted on the low-voltage side in the substation;

under the wiring mode, any main transformer in the station has a fault, and the load carried by the main transformer can be transferred to another main transformer in the station through the bus coupler switch.

When the high-voltage transformer substation is internally configured with three main transformers, the low-voltage side in the high-voltage transformer substation can adopt a single-bus four-segment wiring mode;

in the wiring mode, if no self-switching and tripping device is arranged in the station, when one main transformer in the middle fails, the load carried by the main transformers can be jointly transferred through the main transformers on both sides, but when the main transformers on both sides fail, the load can be transferred only through the middle main transformer. If the station is internally provided with the automatic switching and continuous tripping device, when any main transformer in the station breaks down, the loads of the broken main transformers can be equally distributed by the other two main transformers.

When the high-voltage transformer substation is internally configured with three main transformers, the low-voltage side in the substation can also adopt a single-bus six-section wiring mode;

under the wiring mode, when any main transformer in the station has a fault, the load carried by the main transformer can be equally distributed to other two main transformers in the station. Therefore, when three main transformers exist, the condition of bus four-section wiring with a self-cutting continuous tripping device is the same as that of bus six-section ring type wiring, and when any main transformer in the station breaks down, the load carried by the main transformer can be distributed to other two main transformers in the station.

(2) Value of maximum load rate of main transformer of transformer substation

If the verification of the main transformer N-1 is required, the fault main transformer has two transfer modes, namely direct transfer and indirect transfer. The direct transfer mode is that the carried load is transferred to the main transformer of the same station and the different station which are directly connected with the direct transfer mode; the indirect transfer mode is to transfer the load of the overload part to the main transformer in the communication relationship between the same station and the main transformer by utilizing the overload capacity of the main transformer in the same station. The final states of the two transfer modes are both to ensure that any main transformer is not overloaded.

Taking a 3 × 2 typical substation contact model as an example, if a main transformer No. 1 fails, the direct transfer mode is: the load carried by the main transformer is transferred to No. 2, no. 3 and No. 5 main transformers which are directly communicated with the main transformer; the indirect transfer mode is as follows: the overload capacity of the No. 2 main transformer is utilized (the overload coefficient is assumed to be 1.3), and the load of the overload part of the No. 2 main transformer is transferred to the No. 4 and No. 6 main transformers which are directly communicated with the overload part of the No. 2 main transformer. The basic idea of the main transformer reasonable load rate calculation method meeting the main transformer N-1 verification is as follows: when a direct transfer mode is considered, the non-fault main transformer does not overload after equally dividing the load of the fault main transformer, and the load ratios of all the main transformers are calculated; when an indirect transfer mode is considered, the bottleneck effect of the overload coefficient of the main transformer of the same station in the load transfer process of the fault main transformer needs to be considered at the same time.

The method for calculating the ideal load rate of the main transformer under the typical model (the method for calculating the maximum load rate of the main transformer of the high-voltage transformer substation based on the typical contact model) comprises the following steps:

a.1 Main Transformer direct transfer and Indirect transfer

The method constructs a typical contact model of the transformer substation, calculates the main transformer load rate under the typical model, and firstly analyzes the main transformer load rate under the condition of meeting the main transformer 'N-1' principle.

Definition 1 direct transfer: the direct transfer means that when a certain main transformer is subjected to the "N-1" verification, the load on the main transformer is transferred to each main transformer directly connected to the main transformer by only one switching operation.

Definition 2 indirect transfer: the indirect transfer means that when a certain main transformer is subjected to 'N-1' verification, the main transformer firstly performs one-time transfer to transfer the carried load to the main transformers in the station and between the stations which are directly communicated with the main transformer; if the main transformer in the station is overloaded, the overloaded part of load needs to be transferred to other main transformers which are in communication with the main transformer.

When the No. 1 main transformer has faults, the direct transfer is to transfer the load of the No. 1 main transformer out through the No. 2, no. 3 and No. 5 main transformers directly connected with the No. 1 main transformer. Suppose that the load of the No. 1 main transformer is not transferred after the load transferred by the No. 2, no. 3 and No. 5 main transformers reaches the rated load of No. 2 and No. 3. The indirect transfer is that the No. 2 main transformer which is in the same station with the No. 1 main transformer transfers the No. 1 main transformer residue to the No. 4 and No. 6 main transformers on the premise of meeting the overload capacity of the main transformers.

The typical substation contact model meets the following conditions:

(1) The capacities S of all main transformers in the transformer substation are the same, and main transformers in the transformer substation are interconnected, namely, the low-voltage side in the double-main-transformer substation adopts single-bus segmented wiring, and the low-voltage side in the three-main-transformer substation adopts single-bus six-segmented ring wiring.

(2) The transformer substation station contact channels are the same, and the requirement for transfer capacity can be met.

(3) The main transformer of the inter-station communication adopts direct transfer; when the main transformer in communication in the station considers that the overload coefficient k =1.3, because the main transformer can only allow short-time overload, the load of the overload part is transferred to the main transformer in communication between the stations by adopting indirect transfer, and after the main transformer fails, other main transformers except the main transformer with the fault all reach rated load after the load transfer is completed.

A.2 calculation method

The method for calculating the maximum load rate of the main transformer based on the typical contact model takes a simplified network topology structure of a power distribution network as an example, and the method for calculating the maximum load rate of the main transformer based on the typical contact model is described in detail.

1) Determining transformer substation main transformer contact relation matrix

According to the main transformer contact relation of the transformer substations, if the two transformer substations are in contact, the contact is marked as 1, and if the two transformer substations are not in contact, the contact is marked as 0, and a matrix with 6 rows and 6 columns is established.

According to the matrix condition table, the A transformer substation No. 1 main transformer is in contact with the A transformer substation No. 2 main transformer, the B transformer substation No. 1 main transformer and the C transformer substation No. 1 main transformer, and is not in contact with the B transformer substation No. 2 main transformer and the C transformer substation No. 2 main transformer.

2) Main transformer capacity matrix for participating in load transfer of main transformer fault

If the contact capacity of a line with the 10kV rate is not considered and the overload operation is carried out when the main transformer shortens, the main transformer capacity sequence of a certain main transformer fault participating in load transfer band = the main transformer contact relation matrix of a transformer substation x the oblique angle matrix with the main transformer capacity.

Taking the contact group with the main transformer of the A transformer substation 1 as the center as an example, the main transformer of the A transformer substation 1 is in contact with the main transformer of the A transformer substation 2, the main transformer of the B transformer substation 1 and the main transformer of the C transformer substation 1, so that the main transformer capacity of the A transformer substation 1 is respectively the main transformer of the A transformer substation 2, the main transformer of the B transformer substation 1 and the main transformer of the C transformer substation 1, which participate in load transfer.

3) Contact group maximum load rate matrix

When a main transformer fails, its load is transferred to other main transformers in its contact group, and the contact group maximum load rate = the total capacity of the contact group lost for a main transformer divided by the total capacity of the contact group.

Taking the contact group with the main transformer of the A transformer substation No. 1 as the center as an example, when the main transformer of the A transformer substation No. 1 breaks down, the maximum load rate of the contact group with the main transformer of the A transformer substation No. 1 as the center is 0.7814.

4) Load transfer matrix for contact team

The load transfer zone of the contact group can be calculated according to the maximum load rate of the contact group, for example, when the main transformer of the a substation 1 has a fault, the load which needs to be transferred to the main transformer of the a substation 2 = capacity x of the main transformer of the a substation 2 (1-maximum load rate of the contact group), and the load which needs to be transferred to the main transformer of the B substation 1 is also the above calculation method.

Taking the contact group with the main transformer of the A transformer substation 1 as the center as an example, when the main transformer of the A transformer substation 1 breaks down, the main transformers of the A transformer substation 2, the B transformer substation 1 and the C transformer substation 1 respectively carry loads of 8.74 MW, 8.74 MW and 13.78 MW.

5) Secondary transfer load matrix considering 130% limitation of overload operation during main shortening

When the No. 1 main transformer of the A transformer substation fails, the load can be transferred to the No. 2 main transformer of the A transformer substation, and then the No. 2 main transformer of the A transformer substation is supplied to the No. 1 main transformer of the B transformer substation and the No. 1 main transformer of the C transformer substation.

When the No. 1 main transformer of the A transformer substation has a fault, the No. 1 main transformer of the B transformer substation transfers the supply load = (main short-time overload load rate-1) x the total number of main transformers of the No. 1 main transformer capacity of the A transformer substation/the number of main transformers of the No. 1 main transformer fault transferable belt of the A transformer substation, and the No. 1 main transformer transfer supply load of the C transformer substation is also the calculating method.

Taking the contact group with the transformer substation A No. 1 as the center as an example, when the transformer substation A No. 1 breaks down, the secondary transfer loads of the transformer substations B No. 1 and C No. 1 are both 6MW.

6) Load matrix considering main transformer interconnection line capacity limitation

Load matrix considering intra-station contact between main transformers and 10kV line contact capacity between main transformers and considering main transformer contact line capacity limitation

Taking the contact group with the transformer of the transformer substation A No. 1 as the center as an example, when the transformer substation A No. 1 fails, the transformer substation A No. 2 can transfer the load to the transformer substation A No. 2 to 40MW.

7) Modified load transfer matrix

And comprehensively considering a load transfer matrix of the contact group, a secondary transfer load matrix limited by 130% of overload operation during main shortening and the minimum value of the load matrix considering the capacity limit of the main transformer contact line, namely the corrected load transfer matrix.

Taking the contact group with the transformer substation A No. 1 as the center as an example, when the transformer substation A No. 1 breaks down, the transformer substations A No. 2, B and C No. 1 can actually carry loads of 4.37, 6 and 6MW respectively.

8) Correction calculation matrix for maximum load rate of contact group

And calculating the maximum load rate of the contact group according to the corrected load transfer band matrix correction, for example, the load rate of the main transformer of the A substation No. 1 = (8.74 +6 +) 40=0.52, the load rate of the main transformer of the A substation No. 2 = (40-8.74)/40 =0.78, and the like.

Taking the contact group with the main transformer of the A transformer substation No. 1 as the center as an example, when the load ratios of the main transformer of the A transformer substation No. 1, the main transformer of the A transformer substation No. 2, the main transformer of the B transformer substation No. 1 and the main transformer of the C transformer substation No. 1 are 0.52, 0.78, 0.85 and 0.9 respectively.

9) Maximum average load rate of main transformer

The maximum load rate of the main transformer of the system can only be one, and the minimum value of each column in the calculation matrix is corrected through the maximum load rate of the contact group.

4.2 method for calculating open capacity of high-voltage substation under conventional condition

The open capacity calculation formula of the high-voltage substation under the conventional condition is as follows:

in the formula, k _gb Opening capacity for the high voltage substation; alpha is alpha _gb The maximum load rate of the high-voltage transformer substation; delta _gb The power factor of a high-voltage transformer substation is generally 0.98; r _gb Capacity of the high voltage substation; p is _gb The maximum load exists for the high-voltage transformer substation.

4.3 method for calculating open capacity of power distribution network equipment based on novel power system

A flow schematic diagram of a method for calculating the open capacity of power distribution network equipment based on a novel power system is shown in fig. 2.

4.3.1 maximum Admission Capacity of distributed Power sources of Power distribution network Equipment

1) Maximum acceptance capacity of 10kV distribution transformer for distributed power supply

The maximum capacity of the distribution transformer accessed to the distributed photovoltaic is mainly determined by the distribution transformer capacity, the distribution transformer load, the non-heavy-load operation of the feedback power flow and the voltage deviation meeting the guiding rule requirement.

The calculation method of the maximum accessible distributed photovoltaic capacity of the distribution transformer comprises the following steps:

P _pbf -P _pbmin ＝α _pb R _pb δ _pb (4)

in the formula, P _pbf The maximum capacity of the distributed power supply is accessed for 10kV distribution transformer; p is _pbmin The load is the minimum load daily load of a 10kV distribution transformer benchmark year; alpha is alpha _pb The load factor of the distribution transformer is 10kV, and the value is generally less than or equal to 80 percent; r is _pb The capacity is 10kV distribution and transformation capacity; delta. For the preparation of a coating _pb The power factor of the distribution transformer is 10kV, and is generally 0.9; u shape _pbf Distributing and transforming the low-voltage side bus voltage after the distributed power supply is connected; u shape _pbN To distribute the low side bus voltage.

In the embodiment of the invention, a flowchart of a method for calculating the maximum accessible distributed power capacity of a 10kV distribution transformer is shown in fig. 3.

4.3.2 Maximum acceptance of 10kV line to distributed power supply

The maximum capacity of the 10kV accessed distributed photovoltaic is mainly determined by the power supply capacity of a 10kV line, the load size of the 10kV line and the operation requirement (no-heavy-load operation requirement) of a reverse transmission power flow N-1, and the voltage deviation meets the requirement of the guiding rule.

In the formula, P _zxlf The maximum capacity of the distributed power supply is accessed for the 10kV line; p _zxlmin The load is the minimum load daily load of a 10kV line benchmark year; u shape _zxlN 10 kilovolts nominal; i is the safe current of a 10kV line; delta _zxl For power factor, generally 0.95 is taken; alpha (alpha) ("alpha") _zxl Maximum load of 10kV lineThe rate is 50% of single link, 66.67% of two links, 75% of triple link and 80% of single radiation link.

In the embodiment of the present invention, a flowchart for calculating the maximum distributed power capacity that a 10kV line can access is shown in fig. 4.

4.3.2 maximum accepting capability of high-voltage substation for distributed power supply

The maximum capacity of the high-voltage transformer substation accessed to the distributed photovoltaic is mainly determined by the power supply capacity of the high-voltage transformer substation, the load size of the high-voltage transformer substation and the operation requirement (no-overloading operation requirement) of the reverse power flow N-1, and the short-circuit current, the voltage deviation and the voltage quality meet the guidance requirement.

P _gbf -P _gbmin ＝α _gb R _gb δ _gb (8)

I _xz ＞I _m (9)

I _xzh ＞I _h (11)

In the formula, P _gbf The maximum capacity of the distributed power supply is accessed to the high-voltage substation; p _zxlmin The minimum load daily load of a reference year of the high-voltage transformer substation; alpha is alpha _gb The maximum load rate under the condition of N-1 is met for the high-voltage transformer substation; delta. For the preparation of a coating _gb The power factor of a high-voltage transformer substation is generally 0.98; r is _gb Capacity of the high voltage substation; i is _xz Short-circuit current is the system bus; I.C. A _m Is an allowable short circuit current value; u shape _gbf The voltage value is the voltage value of the high-voltage transformer substation after the connection; u shape _gbN The nominal voltage value is the nominal voltage value of the high-voltage transformer substation; i is _xzh Is the h harmonic current value; i is _h The h-th harmonic current limit specified for GB/T14549.

In the embodiment of the invention, the calculation process of the maximum distributed power capacity accessible to the high-voltage substation is shown in fig. 5.

4.4 Power distribution network device open capacity based on novel Power System

The power distribution network equipment based on the novel power system can access flexible resources such as distributed power sources and energy storage, the power supply capacity of the power distribution network equipment can be increased by the aid of the factors, and the openable capacity of the power distribution network equipment is further increased.

Considering factors of a distributed power supply and energy storage, a calculation formula of the open capacity of the 10kV distribution transformer is as follows:

in the formula, k _xpb The open capacity of the 10kV distribution transformer is considered; alpha (alpha) ("alpha") _pb The maximum load rate of the distribution transformer is 10kV, and the value is generally 80%; r is _pb The capacity is 10kV distribution and transformation capacity; delta. For the preparation of a coating _pb The power factor of the distribution transformer is 10kV, and is generally 0.9; p is _pb The maximum load exists for the 10kV distribution transformer; p _pbfc The output of the distributed power supply under the condition of the maximum load of the 10kV distribution transformer is realized; p _pbc The load capacity is reduced for the energy storage under the condition of maximum load of a 10kV distribution transformer.

Considering factors of a distributed power supply and energy storage, a calculation formula of the open capacity of the 10kV line is as follows:

in the formula, k _zxl Is the open capacity of a 10kV line; u shape _zxlN Is the nominal voltage of the 10kV line; i is the safe current of a 10kV line; delta. For the preparation of a coating _zxl For power factor, generally 0.95 is taken; alpha is alpha _zxl The maximum load rate of the 10kV line is 50% of the single interconnection line, 66.67% of the two interconnection lines, 75% of the triple interconnection line and 80% of the single radiation line. P _zxl The existing maximum load of a 10kV line. P is _zxlfc The output of the distributed power supply under the condition of the maximum load of a 10kV line is realized; p _zxlc The energy storage and load reduction capability is realized under the condition of the maximum load of a 10kV line.

Considering the factors of distributed power supply and energy storage, the open capacity calculation formula of the high-voltage transformer substation is as follows:

in the formula, k _gb Opening capacity for the high voltage substation; alpha is alpha _gb The maximum load rate of the high-voltage transformer substation; delta _gb The power factor of a high-voltage transformer substation is generally 0.98; r _gb Capacity of the high voltage substation; p _gb The maximum load exists for the high-voltage transformer substation; p is _gbfc The distributed power supply is powered on under the condition of the maximum load of the high-voltage transformer substation; p _gbc The load capacity is reduced for energy storage under the condition of the maximum load of the high-voltage transformer substation.

4.5 open capacity calculation method for power distribution system

4.5.1 calculation method for open capacity of power distribution system under conventional condition

Under the conventional condition, the open capacity of the power distribution system is the superposition of the open capacities of the high-voltage transformer substations, so the open capacity calculation formula of the power distribution system is as follows:

wherein, the open capacity sum of the circuit that single transformer substation takes in distribution system is not more than this transformer substation can open capacity, promptly:

the sum of the open capacity of distribution transformers carried by a single line in the power distribution system is not more than the openable capacity of the line, namely:

in the formula, k _cpx Capacity can be opened for the power distribution system under the conventional condition; k is a radical of _gbi Capacity can be opened for the ith high-voltage substation; k is a radical of _gb Capacity can be opened for a high-voltage transformer substation; k is a radical of _zxlj The capacity can be opened for the jth 10kV line; k is a radical of formula _zxl The open capacity of the 10kV line is realized; k is a radical of _pbe The openable capacity was allocated for the e 10 kV.

4.5.2 method for calculating open capacity of power distribution network facing novel power system

Except for the open capacity of a power distribution system under the conventional condition, the interruptible load reduced by demand side management and the open capacity superposition caused by the fact that a distributed power source and an energy storage access power distribution system are overlapped are also considered for the active power distribution network facing the novel power system, so that the calculation formula of the openable capacity of the active power distribution network facing the novel power system is as follows:

k ₁ ＝k _cpx +ΔP+P _x +S _c (18)

wherein Δ P is an interruptible load reduced with the passing demand response; p _x The energy is output by new energy under the condition of regional maximum load; s _c Load capacity is reduced for power distribution system energy storage under regional maximum load conditions.

One) demand response cut-off interruptible load calculation method

P _kz ＝αP _xkz (19)

In the formula, P _kz Interruptible load for demand response; alpha is a demand response coefficient; p _xkz The determined demand response for negotiation with the user may interrupt the payload sum.

The demand side flexible resources can cooperate with the power distribution network to actively participate in the power grid with the aim of economic regulation and control, can be transferred in time or space, have multiple potential types, are constrained by price, an incentive mechanism and infrastructure, have smaller implementation scale and are relatively single in implementation mode. Demand side flexible resources are used as important resources for demand response, and are mainly classified into four categories: flexible resources of electric vehicles, flexible resources of industrial users, flexible resources of commercial users and flexible resources of residential users.

(1) Electric automobile balance resource

The electric automobile participates in the dispatching of the power grid in a charging and switching station mode and is a transferable load. The demand response coefficient of the electric automobile is about 0.2-0.6.

(2) Industrial user flexible resources

The industrial user flexible resources generally have large demand for electric quantity, small load relatively stable peak-valley difference, high speed and high intelligent level, and are important flexible loads in the power system. According to the electricity utilization habit, the industrial high-energy load can be distributed into interruptible loads and translatable loads. Translatable loads are large industrial enterprises that are specifically tailored to shift. The power grid contracts with the users, and the industry can receive the dispatching command of the power grid and arrange the work schedule in the contract period. The response coefficient of the demand of the translatable industrial user is about 0.3-0.5; the interruptible load is mainly an unimportant load in industrial production, and for the load with low power consumption quality, the required power of a user is improved in a mode of reducing the demand of the load, and the peak-valley difference is reduced. The response coefficient of the demand of the translatable industrial user is about 0.6-0.8.

(3) Business user flexible resources

The large commercial users have large power capacity, centralized power consumption time and less flexible scheduling time, and the load is difficult to transfer. The loads that the large commercial users can participate in power grid dispatching mainly include building exterior lights, electric vehicles in building areas, central air conditioners and the like, and in order to reduce the loads, the loads are reduced in the load peak period, and the average power consumption is reduced. The commercial customer demand response coefficient is about 0.6-0.8.

(4) Flexible resource for resident user

About 60% of loads in residential users can be used as flexible loads, and the electricity utilization behavior is changed under the orderly guidance to participate in the dispatching of the power grid. The flexible electric load equipment comprises an intelligent air conditioner, an illumination device, a washing machine, an electric cooker, an electric automobile and the like. The response coefficient of the demands of the residential users is about 0.5-0.7.

II) new energy output characteristic

(1) Power output characteristics of hydroelectric power plant

Due to the influence of the price difference between the peak and the valley of power generation, hydropower often generates power in a centralized way in the daytime and causes the peak of reverse delivery. From the analysis of the sunrise force characteristics, the sunrise force of the hydropower station is 7:00 before small, 19 in the evening: 00 to 21: 00. the output is large, and the output of the hydropower station in autumn and winter is smaller than that in spring and summer in the corresponding lower and higher time periods of the system load. As shown in the schematic diagram of a typical output curve (unit: MW) of a hydroelectric power plant in fig. 6.

(2) Photovoltaic power plant output characteristics

The photovoltaic output changes along with natural factors such as illumination intensity, weather, season, temperature and the like, and has random volatility; the photovoltaic output is concentrated in the daytime, especially in the middle of the day, while the photovoltaic output is zero at night, so that the photovoltaic output is remarkable in time interval and cannot supply power continuously and stably.

From the short-time and sunrise force characteristics, the photovoltaic power generation output has strong volatility and remarkable timeliness. Under the condition of different seasons, the maximum photovoltaic output occurs at different times, but the change is not great, and the typical solar photovoltaic output time is 7:00 to 17: the 00 hours, which are concentrated in the daytime, especially in the midday hours, and the output is zero at night, and thus, the stable supply of electric power cannot be continued. The photovoltaic power generation output and the daytime load matching degree are high, and the photovoltaic power generation output and the daytime load matching degree have positive peak regulation characteristics, but due to the fact that power generation is difficult at night, the photovoltaic power generation output and the daytime load matching degree are difficult to effectively match with the peak at night.

From the annual output characteristic, the photovoltaic power generation output has obvious seasonal characteristic, more power is generated in spring and autumn, and the output in most of the whole year is less than 50% of the installed capacity. The photovoltaic output is similar but different every day in one year, which represents periodicity and non-stationarity of the photovoltaic output. As shown in the typical output curve diagram (unit: MW) of the photovoltaic power plant of fig. 7.

(3) Wind power plant output characteristics

The wind power output changes greatly in each hour, each day and each month within one year, the characteristics of discontinuity and catastrophe are obvious, and no change rule can be stated. On the solar output characteristic, the general trend of change is small in the daytime and large at night, and the daily change condition of the wind power density is basically consistent with the wind speed. On the daily characteristic, the daily variation curve of wind power output has the characteristic of 'one peak and one valley', and the daily variation curve is as follows, 1:00 to 8: maximum 00 output, 12:00 to 17:00 force minimum, day 10:00 to 18: the average output of 00 is less than 18 at night: 00-next day 6: an average force of 00.

Due to the intermittency, randomness and fluctuation of wind power and the characteristics (such as factors of wind speed change, wind shear, yaw error, tower shadow effect and the like) of the wind power plant, the input wind energy of the wind generation set is unstable, the wind power output can fluctuate randomly, and the problem of system frequency stability can be caused. As shown in the schematic diagram of a typical output curve (unit: MW) of the wind power plant of fig. 8.

The embodiment of the invention performs calculation method analysis of the openable capacity of the power distribution system under the conventional condition and calculation method analysis of the openable capacity of the power distribution network facing to the novel power system, and the analysis results out that: the open capacity of the power distribution system is the superposition of the open capacity of the high-voltage transformer substation, and the open capacity of the active power distribution network facing the novel power system is the superposition of the open capacity brought by the fact that the open capacity of the power distribution system is superposed with the open capacity of interruptible loads, distributed power sources and energy storage access power distribution systems reduced by demand side management under the conventional condition.

Example 3

As shown in fig. 9, an openable capacity computing system based on a big data distribution network according to an embodiment of the present invention includes:

the calculation module 1 for the open capacity of the power distribution network equipment under the conventional condition is used for carrying out analysis on selection of power factors, N-1, load rates and loads of a 10kV distribution transformer, a 10kV line and a high-voltage transformer substation under the conventional condition, constructing a mathematical model and determining a calculation method for the open capacity of the power distribution network equipment under the conventional condition.

The maximum receiving capacity calculation module 2 of the distributed power supply of the power distribution network equipment is used for analyzing the maximum receiving capacity of each distribution network equipment of a 10kV distribution transformer, a 10kV line and a high-voltage transformer substation under the condition of distributed power supply access, constructing a mathematical model, and analyzing the maximum receiving capacity calculation method of the distributed power supply of the power distribution network equipment under the boundary conditions of N-1, voltage deviation, short-circuit current, harmonic current and the like.

The power distribution network equipment open capacity calculation module 3 in the novel power system is used for determining the power distribution network equipment open capacity calculation method in the novel power system based on the power distribution network equipment open capacity calculation method in the conventional situation and combined with the influence of the distributed power supply acceptance capacity and energy storage of each power distribution network equipment.

In the above embodiments, the descriptions of the respective embodiments have respective emphasis, and reference may be made to the related descriptions of other embodiments for parts that are not described or illustrated in a certain embodiment.

For the information interaction, execution process and other contents between the above-mentioned devices/units, because the embodiments of the method of the present invention are based on the same concept, the specific functions and technical effects thereof can be referred to the method embodiments specifically, and are not described herein again.

It will be apparent to those skilled in the art that, for convenience and brevity of description, only the above-mentioned division of the functional units and modules is illustrated, and in practical applications, the above-mentioned function distribution may be performed by different functional units and modules according to needs, that is, the internal structure of the apparatus is divided into different functional units or modules to perform all or part of the above-mentioned functions. Each functional unit and module in the embodiments may be integrated in one processing unit, or each unit may exist alone physically, or two or more units are integrated in one unit, and the integrated unit may be implemented in a form of hardware, or in a form of software functional unit. In addition, specific names of the functional units and modules are only for convenience of distinguishing from each other, and are not used for limiting the protection scope of the present invention. The specific working processes of the units and modules in the system may refer to the corresponding processes in the foregoing method embodiments, and are not described herein again.

2. The application example is as follows:

application example 1

The method for calculating the open capacity of the power distribution network equipment based on the novel power system can be applied to power distribution networks in demonstration areas and development areas of certain provinces.

1. And inputting information such as distribution transformer capacity, access photovoltaic capacity, load, line length, line section, transformer substation capacity and the like into a system, and performing accessible distributed photovoltaic capacity simulation on each level of equipment. The diagram of the distribution transformer accessible distributed photovoltaic simulation system is shown in fig. 10, the diagram of the line accessible distributed photovoltaic simulation system is shown in fig. 11, and the diagram of the substation accessible distributed photovoltaic simulation system is shown in fig. 12.

2. According to the system simulation result, the accessible distributed photovoltaic capacity of each level of equipment is obtained, and the specific conditions are shown in the following table.

Table 1 distribution variable access distributed photovoltaic capacity simulation result table under algorithm of the present invention

Table 2 simulation result table of circuit-accessible distributed photovoltaic capacity under algorithm of the present invention

Table 2-1 simulation result table of transformer substation accessible distributed photovoltaic capacity under algorithm of the present invention

3. Except for the open capacity of a power distribution system under the conventional condition, the interruptible load reduced by demand side management and the open capacity superposition brought by a distributed power source and an energy storage access power distribution system need to be considered for the active power distribution network of a novel power system, wherein the interruptible load is 10% of the maximum load of the current situation of the area, and the interruptible load is calculated as follows:

the conventional open capacity of a power distribution system in a demonstration area is 33.53MVA, the open capacity of power distribution network equipment in a novel power system is determined by considering photovoltaic output, energy storage reduction load capacity and interruptible load, and the openable capacity of a demonstration area in a certain province is calculated to be 51.49MVA.

Table 3 calculation result table of open capacity of demonstration area of a certain province under the algorithm of the present invention

Application example 2

An embodiment of the present invention provides a computer device, including: at least one processor, a memory, and a computer program stored in the memory and executable on the at least one processor, the processor implementing the steps of any of the various method embodiments described above when executing the computer program.

Application example 3

Embodiments of the present invention further provide a computer-readable storage medium, where a computer program is stored, and when the computer program is executed by a processor, the steps in the above method embodiments may be implemented.

Application example 4

The embodiment of the present invention further provides an information data processing terminal, where the information data processing terminal is configured to provide a user input interface to implement the steps in the above method embodiments when implemented on an electronic device, and the information data processing terminal is not limited to a mobile phone, a computer, or a switch.

Application example 5

The embodiment of the present invention further provides a server, where the server is configured to provide a user input interface to implement the steps in the above method embodiments when implemented on an electronic device.

Application example 6

Embodiments of the present invention provide a computer program product, which, when running on an electronic device, enables the electronic device to implement the steps in the above method embodiments.

The integrated unit, if implemented in the form of a software functional unit and sold or used as a stand-alone product, may be stored in a computer readable storage medium. Based on such understanding, all or part of the flow of the method according to the embodiments of the present invention may be implemented by a computer program, which may be stored in a computer-readable storage medium and used for instructing related hardware to implement the steps of the embodiments of the method according to the embodiments of the present invention. Wherein the computer program comprises computer program code, which may be in the form of source code, object code, an executable file or some intermediate form, etc. The computer readable medium may include at least: any entity or device capable of carrying computer program code to a photographing apparatus/terminal apparatus, a recording medium, computer memory, read-only memory (ROM), random Access Memory (RAM), electrical carrier signal, telecommunications signal, and software distribution medium. Such as a usb-disk, a removable hard disk, a magnetic or optical disk, etc.

3. Evidence of the relevant effects of the examples:

the embodiment of the invention achieves some positive effects in the process of research and development or use, and has great advantages compared with the prior art.

The existing power distribution network openable capacity calculation method only considers the factors of a wiring mode, N-1, a load rate and a maximum load, and does not consider the influence of novel elements such as distributed photovoltaic and energy storage on the openable capacity of the power distribution network.

The embodiment of the invention determines a calculation method of the open capacity of the distribution network equipment under a novel power system based on the open capacity of the three-level distribution network equipment of a 10kV distribution transformer, a 10kV line and a high-voltage transformer substation under the conventional condition and considering the photovoltaic output and the energy storage load reduction capacity. The method for calculating the maximum open capacity of the power distribution network equipment under the condition of distributed power supply access comprehensively considers boundary conditions such as power supply capacity, power factor, N-1, load rate, maximum load, voltage deviation, harmonic current and short-circuit current of the power transformation equipment and lines with the maximum target of the maximum open capacity of the distributed power supply access.

And calculating the open capacity of a power distribution system in a demonstration area of a province by adopting the conventional method for calculating the open capacity of the power distribution network, wherein the open capacity of the power distribution system is 33.53MVA. The open capacity of each hierarchical distribution equipment is shown in the following table.

Table 4 calculation result table of distribution transformer open capacity under the existing method

Table 5 open capacity calculation result table for 10kV line under existing method

TABLE 3-1 open capacity calculation result table for transformer substation under existing method

According to the calculation method for the open capacity of the power distribution network, which is adopted by the embodiment of the invention, the open capacity of the regional power distribution system is 51.49MVA. The open capacity of each hierarchical distribution equipment is shown in the following table.

Table 6 distribution transformer open capacity calculation result table under algorithm of the present invention

Table 7 calculation result table of 10kV line open capacity under the algorithm of the present invention

Table 8 calculation result table of open capacity of transformer substation under algorithm of the present invention

Compared with the prior art, the algorithm disclosed by the invention has the advantages that the influences of distributed photovoltaic, energy storage and interruptable load are considered, the area open capacity is improved by 53.56% compared with the prior art, the system open capacity under a novel power system is reasonably calculated, the power grid construction investment is effectively delayed through the coordination of source network load storage, the system standby capacity is prevented from being greatly increased according to the prior calculation method, and the quality improvement and the efficiency improvement of a power distribution system are realized.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention, and the scope of the present invention is not limited thereto, and any modification, equivalent replacement, and improvement made by those skilled in the art within the technical scope of the present invention disclosed herein, which is within the spirit and principle of the present invention, should be covered by the present invention.

Claims

1. A method for calculating the open capacity of a large data distribution network is characterized by comprising the following steps:

s1, comprehensively analyzing boundary conditions of power supply capacity, power factor, N-1 degree, load rate, maximum load, voltage deviation, harmonic current and short-circuit current of power distribution network equipment by taking the maximum access capacity of a distributed power supply as a target, and constructing a plurality of mathematical models; calculating the maximum access capacity of the distributed power supply of the power distribution network equipment;

s2, comprehensively analyzing upper and lower level constraints of open capacities of a distribution transformer, a line and a transformer substation based on the constructed mathematical model for calculating the maximum access capacity of the distributed power supply of the power distribution network equipment, and analyzing the open capacity brought by interruptible loads, the distributed power supply and an energy storage access power distribution system which are reduced by demand side management; and a plurality of mathematical models are constructed based on the open capacity of the power distribution equipment and the power distribution system, and the open capacity of the power distribution network equipment under the novel power system is calculated.

2. The method for calculating the openable capacity of the large data distribution network according to claim 1, wherein in step S1, the calculation of the maximum access capacity of the distributed power sources of the distribution network equipment, including the calculation of the maximum receiving capacity of the distribution transformer for the distributed power sources, is performed according to the following calculation formula:

P _pbf -P _pbmin ＝α _pb R _pb δ _pb

in the formula, P _pbf The maximum capacity of the distributed power supply is accessed for 10kV distribution transformer; p _pbmin The load is the minimum load daily load of a 10kV distribution transformer benchmark year; alpha is alpha _pb The load factor of the distribution transformer is 10 kV; r _pb The capacity is 10kV distribution and transformation capacity; delta _pb The power factor is 10kV distribution and transformation power factor; u shape _pbf Distributing and transforming a low-voltage side bus voltage after the distributed photovoltaic is connected; u shape _pbN To distribute the low side bus voltage.

3. The method for calculating the openable capacity of the large data distribution network according to claim 1, wherein in step S1, the calculating the maximum access capacity of the distributed power sources of the distribution network equipment further includes calculating the maximum receiving capacity of the lines to the distributed power sources, and the calculation formula is as follows:

in the formula, P _zxlf The maximum capacity of the distributed power supply is accessed for the 10kV line; p is _zxlmin The load is the minimum load daily load of a 10kV line benchmark year; u shape _zxlN 10 kilovolts nominal; i is the safe current of a 10kV line; delta _zxl Is the power factor; alpha is alpha _zxl The maximum load rate of a 10kV line is 50% of a single interconnection line, 66.67% of two interconnection lines, 75% of a triple interconnection line and 80% of a single radiation line; u shape _zxlif And i is the voltage of each 10kV line after the distributed power supply is connected, and is the 10kV line section.

4. The method for calculating the openable capacity of the large data distribution network according to claim 1, wherein in step S1, the calculating the maximum access capacity of the distributed power sources of the distribution network equipment further comprises calculating the maximum receiving capacity of the distributed power sources by the high-voltage substation, and the calculation formula is as follows:

P _gbf -P _gbmin ＝α _gb R _gb δ _gb

I _xz ＞I _m

I _xzh ＞I _h

in the formula, P _gbf The maximum capacity of the distributed power supply is accessed to the high-voltage substation; p _zxlmin The minimum load daily load of a reference year of the high-voltage transformer substation; alpha is alpha _gb The maximum load rate under the condition of N-1 is met for the high-voltage transformer substation; delta _gb Is the high voltage substation power factor; r _gb Capacity of the high voltage substation; I.C. A _xz Short-circuit current is provided for a system bus; I.C. A _m Is an allowable short circuit current value; u shape _gbf The voltage value is the voltage value of the high-voltage transformer substation after the high-voltage transformer substation is connected; u shape _gbN The nominal voltage value is the nominal voltage value of the high-voltage transformer substation; i is _xzh Is the h harmonic current value; I.C. A _h The h-th harmonic current limit specified for GB/T14549.

5. The method for calculating the open capacity of the large data distribution network based on claim 1, wherein in the step S2, the step of analyzing the upper and lower level constraints of the open capacity of the distribution transformer, and the step of analyzing the open capacity brought by the demand side management of the cut interruptible loads, the distributed power sources and the energy storage access distribution system comprises the steps of:

in the formula, k _xpb The open capacity of the 10kV distribution transformer is considered; alpha is alpha _pb The maximum load rate of the distribution transformer is 10kV, and the value is generally 80%; r _pb The capacity is 10kV distribution and transformation capacity; delta. For the preparation of a coating _pb The power factor is 10kV distribution and transformation power factor; p _pb The maximum load exists for the 10kV distribution transformer; p _pbfc The output of the distributed power supply under the condition of the maximum load of the 10kV distribution transformer is realized; p _pbc The load capacity is reduced for the energy storage under the condition of maximum load of a 10kV distribution transformer.

6. The method for calculating the open capacity of the big data distribution network according to claim 1, wherein in step S2, analyzing the upper and lower constraints of the open capacity of the line, and analyzing the open capacity brought by the interruptible load, the distributed power sources and the energy storage access distribution system which are reduced by the demand side management comprises:

in the formula, k _zxl Is the open capacity of a 10kV line; u shape _zxlN Is the nominal voltage of a 10kV line; i is the safe current of a 10kV line; delta _zxl Is the power factor; alpha is alpha _zxl The maximum load rate of the 10kV line is that the single tie line takes a value of 50 percent, the two tie lines take a value of 66.67 percent, and the triple tie line takes a value of 75 percent,The single radiation line takes a value of 80%; p _zxl The load is the existing maximum load of a 10kV line; p _zxlfc The output of the distributed power supply under the condition of the maximum load of a 10kV line is realized; p is _zxlc The energy storage and load reduction capability is realized under the condition of the maximum load of a 10kV line.

7. The big data distribution network openable capacity calculation method according to claim 1, wherein in step S2, analyzing upper and lower constraints of the substation open capacity, and analyzing the open capacity brought by interruptible loads, distributed power sources and energy storage access distribution systems reduced by demand side management comprises:

in the formula, k _gb Opening capacity for the high voltage substation; alpha is alpha _gb The maximum load rate of the high-voltage transformer substation; delta _gb Is a high voltage substation power factor; r _gb The capacity of the high-voltage substation; p _gb The maximum load exists for the high-voltage transformer substation; p _gbfc The distributed power supply is powered on under the condition of the maximum load of the high-voltage transformer substation; p _gbc The load capacity is reduced for energy storage under the condition of the maximum load of the high-voltage transformer substation.

8. The method for calculating the open capacity of the big data distribution network according to claim 1, wherein before step S1, the following steps are performed: and analyzing the selection of distribution transformers, power factors of lines and substations, N-1, load rate and load under the conventional condition, constructing a mathematical model, and determining the calculation method of the open capacity of the power distribution network equipment under the conventional condition.

9. A system for implementing the method for calculating the openable capacity of the big data distribution network according to any one of claims 1 to 8, wherein the system for calculating the openable capacity of the big data distribution network comprises:

the system comprises a power distribution network equipment open capacity calculation module (1) under the conventional condition, a load rate calculation module and a load calculation module, wherein the power distribution network equipment open capacity calculation module (1) is used for analyzing the selection of power factors, N-1, load rates and loads of a distribution transformer, a line and a transformer substation under the conventional condition, constructing a mathematical model and determining a power distribution network equipment open capacity calculation method under the conventional condition;

the maximum receiving capacity calculation module (2) of the distributed power supply of the power distribution network equipment is used for comprehensively analyzing the boundary conditions of the power supply capacity, the power factor, N-1, the load rate, the maximum load, the voltage deviation, the harmonic current and the short-circuit current of the power distribution network equipment with the maximum access capacity of the distributed power supply to construct a plurality of mathematical models; calculating the maximum access capacity of the distributed power supply of the power distribution network equipment;

the mathematical model (3) is calculated based on the maximum access capacity of the distributed power supply of the constructed power distribution network equipment and is used for comprehensively analyzing the upper and lower level constraints of the open capacity of the transformer substation, the circuit and the distribution transformer and analyzing the open capacity brought by interruptible load, the distributed power supply and the energy storage access power distribution system which are reduced by demand side management; and a plurality of mathematical models are constructed based on the open capacity of the power distribution equipment and the power distribution system under the conventional condition, and the open capacity of the power distribution network equipment under the novel power system is calculated.

10. An information data processing terminal, wherein the information data processing terminal is configured to provide a user input interface to implement the method for calculating the openable capacity of the big data distribution network according to any one of claims 1 to 8 when the terminal is executed on an electronic device.