CN113988442A

CN113988442A - Optimization method, device, terminal and storage medium for receiving-end power grid architecture

Info

Publication number: CN113988442A
Application number: CN202111291940.7A
Authority: CN
Inventors: 张菁; 齐晓光; 王颖; 徐田丰; 张丽洁; 陈宇; 柳璐; 万振东
Original assignee: Shanghai Jiaotong University; State Grid Corp of China SGCC; China Power Engineering Consulting Group East China Electric Power Design Institute Co Ltd; Economic and Technological Research Institute of State Grid Hebei Electric Power Co Ltd
Current assignee: Shanghai Jiaotong University; State Grid Corp of China SGCC; China Power Engineering Consulting Group East China Electric Power Design Institute Co Ltd; Economic and Technological Research Institute of State Grid Hebei Electric Power Co Ltd
Priority date: 2021-11-03
Filing date: 2021-11-03
Publication date: 2022-01-28

Abstract

The invention provides a preferred method, a device, a terminal and a storage medium of a receiving-end power grid architecture, wherein the method comprises the following steps: determining at least one layered grid frame planning scheme corresponding to the to-be-implemented grid frame according to the power grid data of the to-be-implemented grid frame; the layered net rack planning scheme comprises a 500kV net rack planning scheme and a 220kV net rack planning scheme; respectively carrying out load flow calculation on each layered net rack planning scheme, and determining evaluation indexes corresponding to each layered net rack planning scheme according to load flow calculation results; aiming at any one layered net rack planning scheme, determining the comprehensive weight of each evaluation index of the layered net rack planning scheme by adopting a comprehensive weighting method, and calculating the comprehensive score of the layered net rack planning scheme based on the comprehensive weight of each evaluation index; and determining an optimal hierarchical net rack planning scheme based on the comprehensive scores of the hierarchical net rack planning schemes. Through the scheme, flexibility and reliability requirements can be guaranteed while the power grid is constructed.

Description

Optimization method, device, terminal and storage medium for receiving-end power grid architecture

Technical Field

The invention relates to the technical field of receiving-end power grids, in particular to a method, a device, a terminal and a storage medium for optimizing receiving-end power grid architecture.

Background

At present, the energy resource distribution and load distribution in China have the problem of extreme mismatching. The characteristics of large scale, long distance and transregional electric energy transmission in China are determined by the intrinsic characteristics of the reverse energy, so that a receiving-end power grid characterized by high-proportion regional external electricity and alternating current-direct current hybrid connection is formed, clean energy consumption is promoted, and green and low-carbon development is promoted.

The 220KV and above receiving-end power grid is a main power transmission network for connecting power plants, substations or substations, mainly undertakes the task of transmitting electric energy, is the basis for realizing the electrification of the whole people in China, and is a key ring for ensuring the renewable energy sources to be transmitted and used.

The construction of the receiving end power grid of 220 kilovolt and above relates to a plurality of aspects of grid frame scheme generation, partition, evaluation preference and the like. In terms of grid scheme generation, a traditional power system planning method usually includes that a planner gives several feasible schemes according to own experience, and then selects a recommended scheme through technical-economic comparison. However, this method only considers the technical and economic aspects, and the reliability and flexibility of the grid operation are not good.

Disclosure of Invention

In view of this, the present invention provides a preferred method, device, terminal and storage medium for receiving-end power grid architecture, which can solve the problem in the prior art that the reliability and flexibility of a receiving-end power grid of 220kV or more are poor.

In a first aspect, an embodiment of the present invention provides a preferred method for receiving-end power grid architecture, including:

acquiring power grid data of a to-be-implemented grid frame;

determining at least one layered grid frame planning scheme corresponding to a grid frame to be implemented according to the power grid data; the layered net rack planning scheme comprises a 500kV net rack planning scheme and a 220kV net rack planning scheme;

respectively carrying out load flow calculation on each layered net rack planning scheme, and determining evaluation indexes corresponding to each layered net rack planning scheme according to load flow calculation results, wherein the evaluation indexes comprise contribution coefficients of renewable energy sources to electric quantity shortage expected values, electric power system flexibility margin shortage risks, N-1 passing rates under an extreme/typical scene operation mode, N-2 passing rates under the extreme/typical scene operation mode and multi-feed-in system generalized short-circuit ratios;

aiming at any one layered net rack planning scheme, determining the comprehensive weight of each evaluation index of the layered net rack planning scheme by adopting a comprehensive weighting method, and calculating the comprehensive score of the layered net rack planning scheme based on the comprehensive weight of each evaluation index;

and determining an optimal hierarchical net rack planning scheme based on the comprehensive scores of the hierarchical net rack planning schemes.

In a second aspect, an embodiment of the present invention provides a preferred apparatus for a receiving-end power grid architecture, including:

the power grid quantity acquisition module is used for acquiring power grid data of the network frame to be implemented;

the hierarchical network frame planning scheme acquisition module is used for determining at least one hierarchical network frame planning scheme corresponding to the network frame to be implemented according to the power grid data; the layered net rack planning scheme comprises a 500kV net rack planning scheme and a 220kV net rack planning scheme;

the evaluation index acquisition module is used for respectively carrying out load flow calculation on each layered grid planning scheme and determining evaluation indexes corresponding to each layered grid planning scheme according to load flow calculation results, wherein the evaluation indexes comprise contribution coefficients of renewable energy sources to electric quantity shortage expected values, electric power system flexibility margin shortage risks, N-1 passing rate in an extreme/typical scene operation mode, N-2 passing rate in the extreme/typical scene operation mode and multi-feed-in system generalized short-circuit ratio;

the comprehensive score calculation module is used for determining the comprehensive weight of each evaluation index of the hierarchical net rack planning scheme by adopting a comprehensive weighting method aiming at any hierarchical net rack planning scheme, and calculating the comprehensive score of the hierarchical net rack planning scheme based on the comprehensive weight of each evaluation index;

and the optimal scheme determining module is used for determining the optimal hierarchical net rack planning scheme based on the comprehensive scores of all the hierarchical net rack planning schemes.

In a third aspect, an embodiment of the present invention provides a terminal, which includes a memory, a processor, and a computer program stored in the memory and executable on the processor, where the processor, when executing the computer program, implements the steps of the method according to any one of the possible implementation manners of the first aspect.

In a fourth aspect, the present invention provides a computer-readable storage medium, where a computer program is stored, and when the computer program is executed by a processor, the computer program implements the steps of the method according to any one of the possible implementation manners of the first aspect.

Compared with the prior art, the embodiment of the invention has the following beneficial effects:

the embodiment of the invention firstly obtains the power grid data of the network frame to be implemented; then determining at least one layered grid frame planning scheme corresponding to the grid frame to be implemented according to the power grid data; the layered net rack planning scheme comprises a 500kV net rack planning scheme and a 220kV net rack planning scheme; respectively carrying out load flow calculation on each layered net rack planning scheme, and determining evaluation indexes corresponding to each layered net rack planning scheme according to load flow calculation results, wherein the evaluation indexes comprise contribution coefficients of renewable energy sources to electric quantity shortage expected values, electric power system flexibility margin shortage risks, N-1 passing rates under an extreme/typical scene operation mode, N-2 passing rates under the extreme/typical scene operation mode and multi-feed-in system generalized short-circuit ratios; finally, aiming at any layered net rack planning scheme, determining the comprehensive weight of each evaluation index of the layered net rack planning scheme by adopting a comprehensive weighting method, and calculating the comprehensive score of the layered net rack planning scheme based on the comprehensive weight of each evaluation index; and determining an optimal hierarchical net rack planning scheme based on the comprehensive scores of the hierarchical net rack planning schemes. Through the scheme, the flexibility and the reliability requirements can be guaranteed while the power grid is constructed.

Drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed to be used in the embodiments or the prior art descriptions will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without inventive exercise.

Fig. 1 is a flowchart of an implementation of a preferred method of receiving-end power grid architecture provided by an embodiment of the present invention;

FIG. 2 is a schematic diagram of a longitudinal segmentation method provided by an embodiment of the present invention;

FIG. 3 is a schematic diagram of an inner ring and an outer ring partitioning method according to an embodiment of the present invention;

FIG. 4 is a radar chart of evaluation indexes provided by an embodiment of the present invention;

fig. 5 is a schematic structural diagram of a preferred device of a receiving-end power grid architecture provided by an embodiment of the present invention;

fig. 6 is a schematic diagram of a terminal according to an embodiment of the present invention.

Detailed Description

In the following description, for purposes of explanation and not limitation, specific details are set forth, such as particular system structures, techniques, etc. in order to provide a thorough understanding of the embodiments of the invention. It will be apparent, however, to one skilled in the art that the present invention may be practiced in other embodiments that depart from these specific details. In other instances, detailed descriptions of well-known systems, devices, circuits, and methods are omitted so as not to obscure the description of the present invention with unnecessary detail.

In order to make the objects, technical solutions and advantages of the present invention more apparent, the following description is made by way of specific embodiments with reference to the accompanying drawings.

Referring to fig. 1, it shows a flowchart of an implementation of a preferred method of receiving-end grid architecture provided by the embodiment of the present invention, which is detailed as follows:

s101: and acquiring the power grid data of the to-be-implemented grid frame.

In this embodiment, the grid data includes existing grid rack data, future grid rack data, and future demand data. Wherein the existing grid structure data comprises network topology, existing substation capacity, existing power supply capacity, line model, capacity, impedance, length, existing space load distribution and size. The future network frame data comprises newly-increased power distribution points and capacity and newly-increased substation distribution points and capacity; the out-of-area electrical drop points and capacities, alternative overhead corridors, line models, capacities, impedances and lengths. The future demand data includes predicted spatial load distribution and size, demand for consumption of electricity from outside the area, and demand for consumption of renewable energy.

S102: determining at least one layered grid frame planning scheme corresponding to a grid frame to be implemented according to the power grid data; the layered net rack planning scheme comprises a 500kV net rack planning scheme and a 220kV net rack planning scheme.

In this embodiment, according to the power grid data, the grid structure to be implemented is planned in a hierarchical and partitioned manner. The 500kV net rack planning scheme provides a plurality of schemes to be selected according to a typical structure and a construction thought of a 500kV power grid.

Specifically, the 500kV grid is structurally mainly used as a provincial grid trunk and an area trunk grid frame, and is also used as the output of an area grid power supply. According to the structural type characteristics, the connection mode between 500kV alternating current power grids can be divided into a single-channel type structure, a channel interconnection type structure, a grid-to-grid type structure, an intensive type structure and the like. From the internal structure of the power grid at the transmitting and receiving ends, two main forms of a ring structure and a grid structure exist. The ring structure is characterized in that the mutual support capability among the transformer stations on the ring network is strong, and the structure is convenient to adjust by receiving power from multiple directions and adopting a mode of ring opening or ring expansion. The grid structure has the characteristics of short circuit, stronger mutual support capability, firm grid structure and convenience for multipoint power input, and has the defects that short circuit current is difficult to control and the accident range is difficult to control by taking measures for splitting the power grid. The ring structure can be divided into a single ring network, a C (U) ring network (semi-ring network) and a double ring network in shape, and the single ring network and the semi-ring network can be easily transited to the double ring network respectively corresponding to different stages of the urban power grid development. The grid structure can be divided into a Chinese character ri, a Chinese character mu, a Chinese character tian and a network type in shape, and is formed by overlapping 500kV ring networks surrounding a plurality of central areas of cities or a plurality of cities. The Chinese character 'ri', mu 'shape, tian' shape and network type correspond to different stages of city expansion, and the transition mode is a double-ring network-Chinese character 'ri' -mu 'shape-tian' shape-network type.

In a receiving-end power grid load center with intensive extra-high voltage alternating current and direct current drop points, the core problem to be solved in 500kV power grid planning is how to ensure safe evacuation of alternating current and direct current receiving power under the condition of meeting the controllable constraint of short circuit current. The construction idea is that an extra-high voltage alternating current main transformer is connected into a bus segmentation mode of the existing power grid, an alternating current and direct current power supply area is reasonably divided, the electrical distance between extra-high voltage main transformers is pulled, the step-down power of each extra-high voltage station is balanced, short-circuit current is effectively controlled, and safe evacuation of alternating current and direct current power is guaranteed.

In one embodiment, the racks to be implemented include existing racks and future racks; the power grid data comprises the existing grid frame data, the future grid frame data and the future demand data; the existing grid structure data comprises an existing network topology structure, existing substation capacity, existing substation distribution points and existing space load distribution; the future grid data comprises the capacity of the newly-added transformer substation and the distribution points of the newly-added transformer substation; the future demand data comprises a predicted spatial load distribution; the 500kV network frame planning scheme comprises a bus segmentation mode of accessing an ultra-high voltage transformer substation into the existing network frame, 500 kV-level power supply subareas and main transformer total capacity required by each 500 kV-level power supply subarea; the specific implementation process of S102 includes:

s201: carrying out load flow calculation on a to-be-implemented grid frame according to the existing grid frame data to obtain a load flow calculation result, and determining optional extra-high voltage alternating current and direct current drop points near the extra-high voltage transformer substation according to the load flow calculation result, the distribution points of the existing transformer substation and the distribution points of the newly-added transformer substation;

s202: determining a bus segmentation mode of the extra-high voltage transformer substation accessed to the existing grid structure based on optional extra-high voltage alternating current and direct current drop points, existing space load distribution and predicted space load distribution near the extra-high voltage transformer substation, wherein the bus segmentation mode comprises transverse segmentation, longitudinal segmentation and inner and outer ring segmentation;

s203: dividing the to-be-implemented grid frame into a plurality of 500 kV-level power supply subareas based on a bus segmentation mode that an extra-high voltage transformer substation is accessed to the existing grid frame;

s204: and determining the total main transformer capacity required by each 500 kV-level power supply partition based on the spatial load distribution of each 500 kV-level power supply partition.

Illustratively, the to-be-implemented grid frame has 2 extra-high voltage transformer substations, and the main transformer capacity is 1200 ten thousand volt-ampere; 23 kilovolt transformer substations with main transformer capacity of 5000 ten thousand volt-ampere are provided. The extra-high voltage alternating current network forms 'two stations and three channels'; 500KV forms a ring network, a C-shaped double-ring network and other structures locally under the large pattern of four transverse lines and two longitudinal lines. The full-caliber installed capacity is 4088 ten thousand kilowatts, wherein the thermal power accounts for over 70 percent, the maximum load is 4013.3 ten thousand kilowatts, the maximum power is 1447 ten thousand kilowatts outside the area and accounts for 36 percent of the maximum load, and the power is input through a power grid of 500 kilovolts or more.

Firstly, the possibility of large-scale new energy and storage layout in the west is judged according to the conditions of extra-high voltage alternating current and direct current drop points selected near an extra-high voltage substation, the predicted space load distribution and size of a to-be-implemented grid frame, the demand for power consumption outside the district, the demand for consumption of renewable energy and the like, and a grid construction idea of transverse division (north-south division) can be avoided as much as possible in order to avoid uneven main voltage reduction of the extra-high voltage substation.

Secondly, a first network construction mode is formulated, namely a network construction idea of longitudinally dividing the extra-high voltage a station and the extra-high voltage b station, wherein 2 main transformers of the extra-high voltage a station (north) supply a north power grid, 4 main transformers of the extra-high voltage a station (south) and the extra-high voltage b station (north) supply a middle power grid, and the extra-high voltage b station (south) supplies a south power grid, as shown in fig. 2. Specifically, the required downward power of the south, the middle and the north sectors is calculated to be about 9000 ten thousand kilowatts, 15000 ten thousand kilowatts and 5000 ten thousand kilowatts through the load size, the capacity-to-load ratio requirement, the reliability standard and the like of the south, the middle and the north sectors, so that 2 main transformers can be used for supplying the south sector, 4 main transformers are used for supplying the middle sector and 2 main transformers are used for supplying the north sector. In order to control the short-circuit current level, the south and north power grids can be divided into power grids by means of 500kV bus segmentation or line opening and the like under the condition, namely, the south, the middle and the north power grids are combined to form a ring respectively. Besides directly unlocking the 1000/500kV electromagnetic ring network, the connection between the south and north 500kV power grids can be weakened by additionally arranging a series reactance, a back-to-back mode and the like, and more sufficient power grid safety margin is provided on the basis of controllable short-circuit current.

In one embodiment, the specific implementation flow of S203 includes:

when the bus segmentation mode is inner and outer ring segmentation, determining load density based on predicted load spatial distribution of a to-be-implemented grid frame and existing load spatial distribution, and dividing an area, with an extra-high voltage alternating current and direct current drop point as a core, around the extra-high voltage alternating current and direct current drop point, of which the load density is higher than a first preset density threshold value into a 500 kV-level power supply partition to construct an inner ring power grid.

Specifically, the embodiment provides a second network construction mode, that is, a network construction idea of dividing the inner ring and the outer ring of the ultra-high voltage a station and the ultra-high voltage b station is derived on the basis of the longitudinal bus segmentation idea, a western power source long bus and an expanded outer ring are constructed, a high-load density inner ring with an ultra-high voltage alternating current and direct current drop point as a core is constructed, and the inner ring and the outer ring form weak connection through bus segmentation switches or back-to-back, as shown in fig. 3. Specifically, a high-load-density inner-loop power grid is defined by combining administrative region division, space load distribution and size prediction, existing substation distribution, newly-added substation distribution and the like of a to-be-implemented grid frame, the lower transmission power required by the inner-loop power grid is calculated to be about 11000 ten thousand kilowatts, and the inner loop can be supplied by 3 main transformers of an extra-high voltage a station and a b station.

In one embodiment, the racks to be implemented include existing racks and future racks; the power grid data comprises the existing grid frame data, the future grid frame data and the future demand data; the existing grid structure data comprises an existing network topology structure, existing substation capacity, existing substation distribution points and existing space load distribution; the future grid data comprises the capacity of the newly-added transformer substation and the distribution points of the newly-added transformer substation; the future demand data comprises a predicted spatial load distribution; the 220kV net rack planning scheme comprises a power grid operation mode, 220kV power supply areas and the maximum access capacity of each 220kV power supply area;

the specific implementation process of S102 further includes:

s301: determining the load density of a plurality of 220kV power supply areas according to the existing space load distribution and the forecast space load distribution, determining the power grid operation mode corresponding to the 220kV power supply areas according to the load density of each 220kV power supply area,

s302: and calculating the short-circuit current of each 220kV power supply district according to the power grid data, and determining the maximum access capacity of different 220kV power supply districts under each power grid operation mode by taking the short-circuit current not greater than a first preset threshold as a constraint condition.

Specifically, in areas with higher load density, 220kV power grids have been transformed into high voltage distribution grids; in areas with low load density, the 220kV power grid is still a backbone power transmission grid. Specifically, the single-side double-loop chain type, the single-side radiation type, the single-loop type, the double-mesh type, the double-loop type and the double-side double-loop chain type are provided.

In one embodiment, the specific implementation flow of S301 includes:

selecting an independent slicing mode as a power grid operation mode in a 220kV power supply slice area with the load density higher than a second preset density threshold, or the electrical distance of a 500kV transformer substation smaller than a preset electrical distance threshold, or 220kV and below, wherein the number of power supplies is smaller than a first preset number threshold;

and selecting a combined operation mode as a power grid operation mode in a 220kV power supply area when the power grid is in an excessive development period, or the number of 220kV power supplies below 220kV is larger than the first preset number threshold, or the number of 220kV communication channels among 500kV power substations is larger than the second preset number threshold.

Specifically, in the process of determining the 220kV grid planning scheme, according to the load density situation, an independent slicing mode is selected in areas with load density higher than a second preset density threshold value, a 500kV transformer substation with a tight electrical distance, and areas with a small power supply of 220kV or below, and a combined operation mode is selected in transition period of power grid development, or in areas with a large power supply of 220kV or below, and areas with a large number of 220kV communication channels between 500kV transformer substations.

Independent slicing scheme mode with a single 500kV transformer substation as core: the independent 500kV outgoing line is generally in four loops or more, the 500kV transformer substation is provided with at least 3 main transformers or more, and if only 3 main transformers are provided, a certain 220kV power supply support is required. And a standby connecting line is arranged between the subarea power grids to supply power to important loads in the supply area in a power grid fault mode (a main power plant or a transformer substation in the supply area).

An N + N combined operation scheme mode formed by combining N main transformers of two 500kV transformer substations is as follows: each 500kV transformer substation combined into a piece has at least 2 main transformers and more than 2 main transformers, and a connecting line between two 500kV transformer substations needs to be in strong connection to meet the trend transfer under the fault.

After determining the 220kV power supply district and the power grid operation mode, in order to avoid the short circuit power flow from exceeding the limit, in this embodiment, a short circuit current does not exceed a first preset threshold value as a constraint condition, and a typical parameter is taken to analyze a general principle of 500kV main transformer capacity and maximum accessed 220kV power supply capacity configured in two power grid operation modes of the 220kV power supply district power grid, as shown in table 1 and table 2, table 1 shows a table of accessing 220kV power supply capacity in the 500kV substation power supply district in an independent operation mode, and table 2 shows a table of accessing 220kV power supply capacity in the 500kV substation power supply district in a combined operation mode.

TABLE 1

TABLE 2

According to the characteristics of economic development of a power grid, load quantity development, region area and the like, cities are divided into three types of regions according to load density. And calculating the short-circuit current of the power supply chip area by combining the calculation methods in the tables 1 and 2.

In the embodiment, the power grid of the embodiment is divided into 6 large 220kV power supply areas, and 3-4 500kV transformer substations in each 220kV power supply area are jointly operated. Two partitioning schemes are given for saturation years:

in the first scheme, 11 220kV power supply districts are originally planned, 12-13 main transformers are expected to be connected into each 220kV power supply district, 220kV power supplies connected into each 220kV power supply district reach 1152MW according to average distribution, the control pressure of the 220kV power grid short-circuit current is higher in the scheme, and short-circuit current limiting measures can be further adopted according to the step S302.

And in the second scheme, assuming that all 500kV main transformers are updated to 18% impedance in saturation year, calculating the short-circuit current at the system side according to 60kA, and taking the interruption capacity of a 220kV switch as constraint, the saturation year needs to be divided into 20 220kV power supply areas, the number of the 500kV main transformers accessed in each 220kV power supply area is not more than 7, and the average power accessed in each area is 633 MW.

S103: and respectively carrying out load flow calculation on each layered net rack planning scheme, and determining evaluation indexes corresponding to each layered net rack planning scheme according to the load flow calculation result, wherein the evaluation indexes comprise the contribution coefficient of renewable energy sources to the expected value of electric quantity insufficiency, the risk of insufficient flexibility margin of the power system, the N-1 passing rate in an extreme/typical scene operation mode, the N-2 passing rate in the extreme/typical scene operation mode and the generalized short-circuit ratio of the multi-feed-in system.

In one embodiment, S103 includes:

by the formula

Obtaining the contribution coefficient of the renewable energy source to the expected value of the electric quantity shortage, wherein B_R-EENSA coefficient representing the contribution of renewable energy to the expected value of the power deficit,

indicating the expected system power shortage before the renewable energy source is accessed,

indicating expected value of system power shortage after renewable energy source access, E_RERepresenting the grid-connected electric quantity of the renewable energy source;

by the formula

Obtaining the risk of insufficient flexibility margin of the power system; wherein f (z) is a probability density function, R, representing the system flexibility margin_fleRepresenting the risk of insufficient flexibility margin of the power system; z represents a power system state variable;

by the formula GSCR ═ max λ (J)_z))^-1Obtaining the generalized short-circuit ratio of the multi-feed-in system; wherein the content of the first and second substances,

J_zrepresenting the weighted impedance matrix, Z, of the AC system_nmRepresenting the impedance between nodes n and m, P_nRepresenting the node n weight.

In this embodiment, the contribution coefficient of the renewable energy to the expected value of the electric quantity insufficiency is defined as a ratio of a variation of the expected value of the electric quantity insufficiency of the system after the grid connection of the renewable energy to the electric quantity of the accessed renewable energy, and can directly reflect the contribution of the renewable energy to the reliability of the system after the grid connection. The index reflects the capability of a power grid planning scheme for coping with the uncertainty of renewable energy, and if the load shedding probability and the expected value of insufficient electric quantity of a system can be effectively reduced by the access of the renewable energy, the power grid can better cope with the influence of the access of the renewable energy, and the safety and reliability performance of the power grid planning scheme is better.

The risk of insufficient flexibility margin of the power system is defined as the convolution of the probability of insufficient flexibility margin and the expected insufficient flexibility margin, and the index can describe the random variable of the flexibility margin from the perspective of probability and consequence. And f (z) calculating the volume difference by using the probability distribution function of uncertain factors such as output probability distribution, load, renewable energy and the like of various flexible resources. The risk of insufficient flexibility margin of the power system reflects the difficulty of flexibility balance brought to a receiving-end power grid by high-proportion renewable energy access, and has the characteristics of directionality, probability, multi-space-time scale characteristics, state dependency and bidirectional conversion.

The N-1 throughput rate in the extreme/typical scenario mode of operation is defined as the sum of the N-1 throughput rates in the extreme scenario and the typical scenario. The N-1 passing rate index in the traditional planning scheme evaluation is specific to a normal operation state or a typical operation scene, and under the background of diversification of operation scenes of a power system, meeting the typical operation scene does not mean meeting an extreme operation scene. Defining an extreme scene of a receiving-end power grid as a scene that a system runs close to a safety boundary, and determining according to system characteristics, for example, a representative extreme scene, namely a reverse peak-shaving scene, means that the output increasing trend of renewable energy in the day is opposite to a system load curve, and the peak-valley difference of the system net load curve is increased after the renewable energy is accessed.

The N-2 pass rate in the extreme/typical scenario mode of operation is defined as the sum of the N-2 pass rates in the extreme scenario and the typical scenario.

The short-circuit ratio is a common measurement index of an electric power system for representing the short-circuit capacity of the system divided by the capacity of equipment, the generalized short-circuit ratio index of the multi-feed-in system can represent the strength of the multi-feed-in direct-current system like the generalized short-circuit ratio of the multi-feed-in system, and can directly distinguish strong and weak alternating-current systems from values like the short-circuit ratio, namely, when the generalized short-circuit ratio of the multi-feed-in system is larger than 3, a strong power grid is formed, between 2 and 3, the weak power grid is formed, and when the generalized short-circuit ratio of the multi-feed-in system is smaller than 2, the weak power grid is formed.

In one embodiment, the evaluation index further comprises a safety reliability index, an economic index, a flexibility index and an environmental protection index;

the safe reliability index comprises an insufficient power probability, an insufficient power expectation and a severity index;

the economic indexes comprise investment cost, running cost, renewable energy consumption cost, internal yield and investment recovery period;

the flexibility indexes comprise a maximum load rate, an average load rate, load unbalance, a load increase margin and a power grid expansion margin;

the environmental protection index includes carbon emission and pollutant emission.

In the present embodiment, the power shortage probability (LOLP), also referred to as the loss of load probability, is conventionally defined as the probability that the available capacity of the power generation system cannot meet the annual maximum load demand of the system.

The Expected energy shortage (ENS) refers to the amount of electricity that is short of the load due to the outage of the power generation equipment during the study period, and the average number of times of load outage due to the insufficient power generation during a certain period (LOLF and the average duration (LOLD) of each outage).

The severity index represents the duration of loss of full load under peak load conditions.

In this embodiment, the consumption cost of renewable energy can be defined as the investment cost of power generation and the investment cost of power transmission network.

The internal yield is the discount rate of 0 accumulated by economic or financial net present value in the calculation period of the power grid planning project and is calculated by a formula

An internal rate of return is calculated, wherein,F_IRRdenotes the internal rate of return, F_ic.tIndicating the cash inflow amount of the t period; f_co.tIndicating the cash outflow at the t-th stage, and Y indicating the project calculator.

The investment recovery period is also called "investment recovery period". The time (years) required for the total amount of income gained after the investment project investment to reach the total amount of investment invested in the investment project. There are several ways to calculate the payback period. According to different starting time of the recovery investment, the calculation from the date of project production and the calculation from the date of use of the investment are carried out; according to different main bodies of the recovery investment, a social investment recovery period and an enterprise investment recovery period are provided; the profit investment recovery period and the profit investment recovery period are different according to the income of the investment recovery.

In the present embodiment, the maximum load rate is the maximum value of all the line load rates.

The degree of load unbalance being an equation for the load rate of all lines, i.e.

Wherein n represents the total number of lines, l_iThe load factor of the ith line is represented, and l represents the average of the load factors of all the lines.

The power grid expansion margin refers to the ratio of the sum of the maximum allowed newly increased outgoing lines of each node in the power grid to the maximum allowed outgoing line number, and can be obtained by a formula

Wherein M represents the maximum allowed outgoing line number of the node, L_jThe number of outgoing lines of the node j is shown, and the number of nodes of the power grid is shown by m.

In this embodiment, the safety reliability index further includes a capacity-to-load ratio and a short-circuit current adequacy. The economic indicators also include total 500kV line length, load and electricity usage. The environmental protection index also comprises the electric power proportion of renewable energy sources and the electric quantity proportion of renewable energy sources.

S104: and aiming at any one hierarchical net rack planning scheme, determining the comprehensive weight of each evaluation index of the hierarchical net rack planning scheme by adopting a comprehensive weighting method, and calculating the comprehensive score of the hierarchical net rack planning scheme based on the comprehensive weight of each evaluation index.

In this embodiment, the comprehensive weighting method includes a subjective weighting method and an objective weighting method, and the Delphi subjective weighting method and the entropy method objective weighting method are respectively used to weight the index, and then the index weights of the two methods corresponding to the same index are weighted and summed to obtain the comprehensive weight corresponding to the index.

In this embodiment, the severity index, the investment cost, the average value of the line load rate, and the carbon emission are selected as representatives, and the Z-score standardization method is adopted to standardize each index based on the average value and the standard deviation of all indexes. The processed data were in accordance with the standard normal distribution, i.e. mean 0 and standard deviation 1. As the four indexes are cost-type (smaller and more excellent types), the visual requirements are considered, the four indexes are converted into profit-type (larger and more excellent types) indexes, the indexes are subjectively weighted, and the comprehensive score is more excellent.

In this embodiment, after the weights of the indexes are obtained through calculation, the scores of the indexes can be calculated according to the comprehensive weights and numerical values of the indexes, and then the classification scores of the categories to which the indexes belong are calculated according to the scores of the indexes, wherein the categories to which the indexes belong include safety and reliability, environmental protection, economy and flexibility. An index radar map is generated from the classification scores of the four major classes, as shown in fig. 4.

S105: and determining an optimal hierarchical net rack planning scheme based on the comprehensive scores of the hierarchical net rack planning schemes.

In this embodiment, the hierarchical net rack planning scheme with the highest comprehensive score is selected as the optimal hierarchical net rack planning scheme.

It should be understood that, the sequence numbers of the steps in the foregoing embodiments do not imply an execution sequence, and the execution sequence of each process should be determined by its function and inherent logic, and should not constitute any limitation to the implementation process of the embodiments of the present invention.

The following are embodiments of the apparatus of the invention, reference being made to the corresponding method embodiments described above for details which are not described in detail therein.

Fig. 5 shows a schematic structural diagram of a preferred device of a receiving-end grid architecture provided by an embodiment of the present invention, and for convenience of description, only the parts related to the embodiment of the present invention are shown, and detailed descriptions are as follows:

as shown in fig. 5, a preferred apparatus 100 of the receiving end grid architecture comprises: .

A power grid number obtaining module 110, configured to obtain power grid data of a grid frame to be implemented;

a hierarchical network frame planning scheme obtaining module 120, configured to determine, according to the power grid data, at least one hierarchical network frame planning scheme corresponding to a network frame to be implemented; the layered net rack planning scheme comprises a 500kV net rack planning scheme and a 220kV net rack planning scheme;

the evaluation index acquisition module 130 is configured to perform load flow calculation on each hierarchical network planning scheme, and determine an evaluation index corresponding to each hierarchical network planning scheme according to a load flow calculation result, where the evaluation index includes a contribution coefficient of renewable energy to an expected value of electric quantity insufficiency, a risk of insufficient flexibility margin of the power system, an N-1 passing rate in an extreme/typical scene operation mode, an N-2 passing rate in an extreme/typical scene operation mode, and a generalized short-circuit ratio of the multi-feed-in system;

a comprehensive score calculation module 140, configured to determine, for any hierarchical network frame planning scheme, a comprehensive weight of each evaluation index of the hierarchical network frame planning scheme by using a comprehensive weighting method, and calculate a comprehensive score of the hierarchical network frame planning scheme based on the comprehensive weight of each evaluation index;

and an optimal scheme determining module 150, configured to determine an optimal hierarchical net rack planning scheme based on the comprehensive scores of the respective hierarchical net rack planning schemes.

In one embodiment, the racks to be implemented include existing racks and future racks; the power grid data comprises the existing grid frame data, the future grid frame data and the future demand data; the existing grid structure data comprises an existing network topology structure, existing substation capacity, existing substation distribution points and existing space load distribution; the future grid data comprises the capacity of the newly-added transformer substation and the distribution points of the newly-added transformer substation; the future demand data comprises a predicted spatial load distribution; the 500kV network frame planning scheme comprises a bus segmentation mode of accessing an ultra-high voltage transformer substation into the existing network frame, 500 kV-level power supply subareas and main transformer total capacity required by each 500 kV-level power supply subarea;

the hierarchical network frame planning scheme obtaining module 120 specifically includes:

the alternating current and direct current drop point determining unit is used for carrying out load flow calculation on the to-be-implemented net rack according to the existing net rack data to obtain a load flow calculation result, and determining optional extra-high voltage alternating current and direct current drop points near the extra-high voltage transformer substation according to the load flow calculation result, the distribution points of the existing transformer substation and the distribution points of the newly-added transformer substation;

the bus segmentation mode determination unit is used for determining a bus segmentation mode of the extra-high voltage transformer substation accessed to the existing grid structure based on optional extra-high voltage alternating current and direct current drop points, existing space load distribution and predicted space load distribution near the extra-high voltage transformer substation, wherein the bus segmentation mode comprises transverse segmentation, longitudinal segmentation and inner and outer ring segmentation;

the 500 kV-level power supply partition dividing unit is used for dividing the to-be-implemented grid into a plurality of 500 kV-level power supply partitions based on a bus segmentation mode that an ultra-high voltage substation is accessed to the existing grid;

and the main transformer total capacity calculating unit is used for determining the main transformer total capacity required by each 500 kV-level power supply partition based on the spatial load distribution of each 500 kV-level power supply partition.

In one embodiment, the 500kV class power supply zoning unit comprises:

a power grid operation mode determining unit used for determining the load density of a plurality of 220kV power supply areas according to the existing space load distribution and the forecast space load distribution, and determining the power grid operation mode corresponding to the 220kV power supply areas according to the load density of each 220kV power supply area,

and the maximum access capacity calculation unit is used for calculating the short-circuit current of each 220kV power supply district according to the power grid data, and determining the maximum access capacity of different 220kV power supply districts in each power grid operation mode by taking the short-circuit current not greater than a first preset threshold as a constraint condition.

In one embodiment, the grid operation mode determining unit includes:

In one embodiment, the evaluation index obtaining module 130 includes:

by the formula

by the formula

through a maleFormula GSCR ═ max λ (J)_z))^-1Obtaining the generalized short-circuit ratio of the multi-feed-in system; wherein the content of the first and second substances,

The embodiment of the invention firstly obtains the power grid data of the network frame to be implemented; then determining at least one layered grid frame planning scheme corresponding to the grid frame to be implemented according to the power grid data; the layered net rack planning scheme comprises a 500kV net rack planning scheme and a 220kV net rack planning scheme; respectively carrying out load flow calculation on each layered net rack planning scheme, and determining evaluation indexes corresponding to each layered net rack planning scheme according to load flow calculation results, wherein the evaluation indexes comprise contribution coefficients of renewable energy sources to electric quantity shortage expected values, electric power system flexibility margin shortage risks, N-1 passing rates under an extreme/typical scene operation mode, N-2 passing rates under the extreme/typical scene operation mode and multi-feed-in system generalized short-circuit ratios; finally, aiming at any layered net rack planning scheme, determining the comprehensive weight of each evaluation index of the layered net rack planning scheme by adopting a comprehensive weighting method, and calculating the comprehensive score of the layered net rack planning scheme based on the comprehensive weight of each evaluation index; and determining an optimal hierarchical net rack planning scheme based on the comprehensive scores of the hierarchical net rack planning schemes. Through the scheme, the method and the device are beneficial to ensuring the requirements of flexibility and reliability while constructing the power grid.

Fig. 6 is a schematic diagram of a terminal according to an embodiment of the present invention. As shown in fig. 6, the terminal 6 of this embodiment includes: a processor 60, a memory 61 and a computer program 62 stored in said memory 61 and executable on said processor 60. The processor 60, when executing the computer program 62, implements the steps in the above-described preferred method embodiments of the respective receiving grid architecture, such as the steps 101 to 105 shown in fig. 1. Alternatively, the processor 60, when executing the computer program 62, implements the functions of the modules/units in the above-mentioned device embodiments, such as the functions of the units 110 to 150 shown in fig. 5.

Illustratively, the computer program 62 may be partitioned into one or more modules/units that are stored in the memory 61 and executed by the processor 60 to implement the present invention. The one or more modules/units may be a series of computer program instruction segments capable of performing specific functions, which are used to describe the execution of the computer program 62 in the terminal 6.

The terminal 6 may be a desktop computer, a notebook, a palm computer, a cloud server, or other computing devices. The terminal 6 may include, but is not limited to, a processor 60, a memory 61. It will be appreciated by those skilled in the art that fig. 6 is only an example of a terminal 6 and does not constitute a limitation of the terminal 6, and that it may comprise more or less components than those shown, or some components may be combined, or different components, for example the terminal may further comprise input output devices, network access devices, buses, etc.

The Processor 60 may be a Central Processing Unit (CPU), other general purpose Processor, a Digital Signal Processor (DSP), an Application Specific Integrated Circuit (ASIC), a Field Programmable Gate Array (FPGA) or other Programmable logic device, discrete Gate or transistor logic, discrete hardware components, etc. A general purpose processor may be a microprocessor or the processor may be any conventional processor or the like.

The memory 61 may be an internal storage unit of the terminal 6, such as a hard disk or a memory of the terminal 6. The memory 61 may also be an external storage device of the terminal 6, such as a plug-in hard disk, a Smart Media Card (SMC), a Secure Digital (SD) Card, a Flash memory Card (Flash Card) and the like provided on the terminal 6. Further, the memory 61 may also include both an internal storage unit and an external storage device of the terminal 6. The memory 61 is used for storing the computer program and other programs and data required by the terminal. The memory 61 may also be used to temporarily store data that has been output or is to be output.

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 application. 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.

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.

Those of ordinary skill in the art will appreciate that the various illustrative elements and algorithm steps described in connection with the embodiments disclosed herein may be implemented as electronic hardware or combinations of computer software and electronic hardware. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the implementation. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present invention.

In the embodiments provided in the present invention, it should be understood that the disclosed apparatus/terminal and method may be implemented in other ways. For example, the above-described apparatus/terminal embodiments are merely illustrative, and for example, the division of the modules or units is only one logical division, and there may be other divisions when actually implemented, for example, a plurality of units or components may be combined or may be integrated into another system, or some features may be omitted, or not executed. In addition, the shown or discussed mutual coupling or direct coupling or communication connection may be an indirect coupling or communication connection through some interfaces, devices or units, and may be in an electrical, mechanical or other form.

The units described as separate parts may or may not be physically separate, and parts displayed as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of the embodiment.

In addition, functional units in the embodiments of the present invention may be integrated into one processing unit, or each unit may exist alone physically, or two or more units are integrated into one unit. The integrated unit can be realized in a form of hardware, and can also be realized in a form of a software functional unit.

The integrated modules/units, if implemented in the form of software functional units and sold or used as separate products, 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 above embodiments may be implemented by a computer program, which may be stored in a computer readable storage medium, and when the computer program is executed by a processor, the steps of the preferred method embodiments of the foregoing receiving-end power grid architecture may be implemented. 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: any entity or device capable of carrying the computer program code, recording medium, usb disk, removable hard disk, magnetic disk, optical disk, computer Memory, Read-Only Memory (ROM), Random Access Memory (RAM), electrical carrier wave signals, telecommunications signals, software distribution medium, and the like. It should be noted that the computer readable medium may contain other components which may be suitably increased or decreased as required by legislation and patent practice in jurisdictions, for example, in some jurisdictions, computer readable media which may not include electrical carrier signals and telecommunications signals in accordance with legislation and patent practice.

The above-mentioned embodiments are only used for illustrating the technical solutions of the present invention, and not for limiting the same; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; such modifications and substitutions do not substantially depart from the spirit and scope of the embodiments of the present invention, and are intended to be included within the scope of the present invention.

Claims

1. A preferred method of receiving grid architecture, comprising: acquiring power grid data of a to-be-implemented grid frame; determining at least one layered grid frame planning scheme corresponding to a grid frame to be implemented according to the power grid data; the layered net rack planning scheme comprises a 500kV net rack planning scheme and a 220kV net rack planning scheme; respectively carrying out load flow calculation on each layered net rack planning scheme, and determining evaluation indexes corresponding to each layered net rack planning scheme according to load flow calculation results, wherein the evaluation indexes comprise contribution coefficients of renewable energy sources to electric quantity shortage expected values, electric power system flexibility margin shortage risks, N-1 passing rates in an extreme/typical scene operation mode, N-2 passing rates in the extreme/typical scene operation mode and multi-feed-in system generalized short-circuit ratios; aiming at any one layered net rack planning scheme, determining the comprehensive weight of each evaluation index of the layered net rack planning scheme by adopting a comprehensive weighting method, and calculating the comprehensive score of the layered net rack planning scheme based on the comprehensive weight of each evaluation index; and determining an optimal hierarchical net rack planning scheme based on the comprehensive scores of the hierarchical net rack planning schemes.

2. A preferred method of receiving grid architecture according to claim 1, wherein the grid to be implemented comprises existing and future grids; the power grid data comprises the existing grid frame data, the future grid frame data and the future demand data; the existing grid structure data comprises an existing network topology structure, existing substation capacity, existing substation distribution points and existing space load distribution; the future grid data comprises the capacity of the newly-added transformer substation and the distribution points of the newly-added transformer substation; the future demand data comprises a predicted spatial load distribution; the 500kV network frame planning scheme comprises a bus segmentation mode of accessing an ultra-high voltage transformer substation into the existing network frame, 500 kV-level power supply subareas and main transformer total capacity required by each 500 kV-level power supply subarea;

the step of determining at least one hierarchical grid planning scheme corresponding to the grid to be implemented according to the power grid data comprises the following steps:

carrying out load flow calculation on a to-be-implemented grid frame according to the existing grid frame data to obtain a load flow calculation result, and determining optional extra-high voltage alternating current and direct current drop points near the extra-high voltage transformer substation according to the load flow calculation result, the distribution points of the existing transformer substation and the distribution points of the newly-added transformer substation;

determining a bus segmentation mode of the extra-high voltage transformer substation accessed to the existing grid structure based on optional extra-high voltage alternating current and direct current drop points, existing space load distribution and predicted space load distribution near the extra-high voltage transformer substation, wherein the bus segmentation mode comprises transverse segmentation, longitudinal segmentation and inner and outer ring segmentation;

dividing the to-be-implemented grid frame into a plurality of 500 kV-level power supply subareas based on a bus segmentation mode that an extra-high voltage transformer substation is accessed to the existing grid frame;

and determining the total main transformer capacity required by each 500 kV-level power supply partition based on the spatial load distribution of each 500 kV-level power supply partition.

3. The receiving-end power grid architecture optimization method according to claim 2, wherein the dividing of the grid frame to be implemented into a plurality of 500 kV-class power supply partitions based on a bus segmentation mode of an existing grid frame accessed by an extra-high voltage substation comprises:

4. A preferred method of receiving grid architecture according to claim 1, wherein the grid to be implemented comprises existing and future grids; the power grid data comprises the existing grid frame data, the future grid frame data and the future demand data; the existing grid structure data comprises an existing network topology structure, existing substation capacity, existing substation distribution points and existing space load distribution; the future grid data comprises the capacity of the newly-added transformer substation and the distribution points of the newly-added transformer substation; the future demand data comprises a predicted spatial load distribution; the 220kV net rack planning scheme comprises a power grid operation mode, 220kV power supply areas and the maximum access capacity of each 220kV power supply area;

determining the load density of a plurality of 220kV power supply areas according to the existing space load distribution and the forecast space load distribution, determining the power grid operation mode corresponding to the 220kV power supply areas according to the load density of each 220kV power supply area,

and calculating the short-circuit current of each 220kV power supply district according to the power grid data, and determining the maximum access capacity of different 220kV power supply districts under each power grid operation mode by taking the short-circuit current not greater than a first preset threshold as a constraint condition.

5. The method for optimizing receiving-end power grid architecture according to claim 1, wherein the determining the power grid operation mode corresponding to each 220kV power supply section according to the load density of each 220kV power supply section comprises:

6. The receiving-end power grid architecture optimization method according to claim 1, wherein the determining evaluation indexes corresponding to the hierarchical grid planning schemes according to the load flow calculation result includes:

by the formula

by the formula

J_zrepresenting the weighted impedance matrix, Z, of the AC system_nmRepresenting the impedance between nodes n and m, P_nRepresenting the weight of node n.

7. The preferred method of receiving grid architecture according to claim 1, wherein the evaluation indicators further include a safety reliability indicator, an economic indicator, a flexibility indicator, and an environmental protection indicator;

8. A preferred apparatus of a receiving end grid architecture, comprising:

9. A terminal comprising a memory, a processor and a computer program stored in the memory and executable on the processor, characterized in that the processor implements the steps of the method according to any of the preceding claims 1 to 7 when executing the computer program.

10. A computer-readable storage medium, in which a computer program is stored which, when being executed by a processor, carries out the steps of the method according to any one of claims 1 to 7.