WO2022242020A1

WO2022242020A1 - Method and system for optimizing direct current transmission limit within planning period

Info

Publication number: WO2022242020A1
Application number: PCT/CN2021/123951
Authority: WO
Inventors: 张红丽; 刘福锁; 李威; 余思聪; 倪禛霖; 王玉; 薛峰; 李兆伟; 吴雪莲; 郜建良; 雷杰
Original assignee: 南瑞集团有限公司; 国电南瑞科技股份有限公司
Priority date: 2021-05-20
Filing date: 2021-10-15
Publication date: 2022-11-24
Also published as: CN113300396A; CN113300396B

Abstract

Disclosed in the present invention are a method and system for optimizing a direct current transmission limit within a planning period. The method of the present invention comprises: performing annual analysis within the planning period; obtaining annual maximum direct current transmittable power; performing unified monetization on abandoned power loss caused by incapability of transmitting direct current at full power, emergency control cost, outsourcing power cost and standby cost to form operation risk cost; calculating total risk cost under each group of risk threshold sequence in combination with multiple groups of risk threshold sequences which are randomly generated; constructing a direct current transmission limit sequence within the planning period by employing the annual maximum direct current transmittable power corresponding to the minimum total risk cost; and reasonably planning a direct current transmission limit, so as to realize seamless connection from planning to operation. Power system planning personnel can be guided to fully consider operation risks after direct current commissioning, thereby realizing power supply-power grid-direct current load collaborative development.

Description

A method and system for optimizing DC transmission limits within a planning period

technical field

The invention relates to a method and system for optimizing DC transmission limits within a planning period, and belongs to the technical field of power grid planning.

Background technique

Vigorously developing renewable energy has become an important strategic consensus for my country's energy development. However, due to planning, management, and technical reasons, the problem of "abandoning water, light, and wind" in my country's renewable energy is very prominent. Taking Sichuan Power Grid as an example, with the three-circuit UHV DC line put into operation in Sichuan, the power structure characteristics of Sichuan Power Grid have been formed. The mismatch of specific conditions can lead to water abandonment. Reasonable planning and construction of UHV DC is an important measure to alleviate the problem of water abandonment and optimize the allocation of energy in the country.

Traditional AC/DC power grid structure optimization research focuses on the impact of primary system strengthening on the demand and capacity of power transmission and reception, and proposes the way of DC drop point and the construction method of AC grid structure to realize the economy and reliability of power supply, and mainly considers power when formulating the planning scheme. Power balance, N-1 constraint and economy, do not consider extreme working conditions with small probability. The operation of the power grid mainly depends on the power grid planning and power design level. Due to the lag in the construction of the UHV AC power grid and the long-term existence of the "strong straight and weak AC" structure, the existing operating limits have taken into account the stability constraints after the extreme working condition N-2 fault , leading to greater security and stability risks in the operation of AC and DC power grids in my country. During the transitional period of DC commissioning, the planned and designed rated capacity is usually not reached, and in the actual operation of DC, it relies too much on the secondary system to make up for the lack of grid structure caused by planning.

The new version of "Guidelines for Power System Safety and Stability" (GB38755-2019) clearly requires that secondary systems such as stability control should be considered in the planning stage of the power grid, and the stability performance of the long-term system should be calculated so that when the stability of the power system is damaged, there can be predetermined Measures to prevent the scope of accidents from expanding and reduce accident losses; at the same time, it is stipulated that the parameter setting and tolerance of secondary equipment (including relay protection devices, safety automatic devices, automation equipment, communication equipment, etc.) of the power system should be the same as those of primary equipment Adapt accordingly. Therefore, in the planning and design stage of DC, there is an urgent need for a DC transmission limit optimization method that considers operational risks.

Contents of the invention

The present invention provides a DC transmission limit optimization method and system within a planning period, which solves the problems disclosed in the background technology.

In order to solve the problems of the technologies described above, the technical solution adopted in the present invention is:

A method for optimizing DC transmission limits within a planning cycle, comprising:

Obtain the typical operating conditions of the sending power grid every year within the planning period;

According to the operating conditions, calculate the annual DC maximum transmittable power subject to the constraints of DC effective short-circuit ratio, AC channel power organization constraints, voltage stability constraints, and frequency stability constraints;

According to the annual DC maximum transmittable power, calculate the cost of power abandonment caused by the failure of DC to send out full power, and adjust all operating conditions;

Based on the adjusted operating conditions, the annual operating risk cost is calculated according to the cost of power abandonment, the cost of purchased power, the cost of backup, and the emergency control cost of the sending power grid under the failure of the second-level safety standard;

Randomly generate multiple groups of risk threshold sequences in the planning cycle, and calculate the total risk cost under each group of risk threshold sequences from the start year to the end year of the planning cycle according to the operating risk cost;

The DC maximum transmittable power corresponding to the minimum total cost of risk is used to construct the DC transmission limit sequence within the planning period.

If the power grid at the sending end is a power grid without new energy transmission, typical operating conditions include Fengda, Fengxiao, Fengpingda, Kuda, Kuxiao and Kupingda;

If the power grid at the sending end is a power grid with new energy sent, typical operating conditions include Fengda, Fengxiao, Fengpingda, Kuda, Kuxiao, Kupingda, new energy Dafa and new energy Xiaofa.

According to the operating conditions, calculate the annual DC maximum transmittable power subject to the constraints of DC effective short-circuit ratio, AC channel power organization constraints, voltage stability constraints, and frequency stability constraints. The specific process is as follows:

Calculate the DC effective short-circuit ratio under all operating conditions to obtain the maximum DC transmission power constrained by the DC effective short-circuit ratio;

Calculate the transmission power of the DC near-area AC section after the AC fault occurs under all operating conditions, and obtain the maximum DC transmission power constrained by the power organization of the AC channel;

Calculate the transient overvoltage and steady overvoltage limitation of the converter station and the AC bus in the DC vicinity under the impact of DC disturbance, and obtain the maximum DC transmission power subject to voltage stability constraints;

Calculate the frequency limitation of the system under the impact of DC disturbance, and obtain the maximum transmittable power of DC subject to the frequency stability constraint;

Calculate the annual DC maximum transmittable power subject to the constraints of DC effective short-circuit ratio, AC channel power organization, voltage stability and frequency stability.

The formula for calculating the electricity abandonment cost is:

Among them, C _discard is the cost of electricity discarding, j and λ ^j are the operating conditions and the probability of operating conditions in which the power arranged by DC is greater than the maximum transmittable power of DC, respectively,

is the maximum transmittable power of DC, k is the unit cost of curtailment, and P ^j is the DC power arranged in operating condition j.

When adjusting all operating conditions, for operating conditions where the power of the DC arrangement is greater than the maximum transmittable power of the DC, adjust the DC power to the maximum transmittable power, and give priority to reducing the output of the supporting power supply.

The formula for calculating the running risk cost is,

Among them, C _risk is the operation risk cost, C _discard is the power abandonment cost, λ ⁱ , ω ^t are the operating condition i probability and the corresponding disturbance probability respectively, C _ec , C _re , C _pur are the emergency control cost, backup cost and The cost of purchased electricity.

Randomly generate multiple groups of risk threshold sequences in the planning cycle, and calculate the total risk cost of each group of risk threshold sequences from the start year to the end year of the planning cycle according to the operating risk cost. The specific process is as follows:

Randomly generate multiple sets of risk threshold sequences in the planning cycle; the start year and end year of each set of risk threshold sequences are consistent with the start year and end year of the planning cycle, and each set of risk threshold sequences includes the risk threshold;

For each set of risk threshold series, optimize the selection of planning measures for the year in which the operating risk cost exceeds the corresponding risk threshold, and calculate the total risk cost under the risk threshold sequence; where the total risk cost is the annual operating risk cost and planning Measures add up in cost.

A DC transmission limit optimization system within a planning period, comprising:

Operating condition acquisition module: acquire the typical operating conditions of the sending power grid every year within the planning period;

Transmittable power module: According to the operating conditions, calculate the annual DC maximum transmittable power subject to the constraints of DC effective short-circuit ratio, AC channel power organization constraints, voltage stability constraints, and frequency stability constraints;

Abandonment cost module: According to the annual DC maximum transmittable power, calculate the electricity abandonment cost caused by the failure of DC to send out full power, and adjust all operating conditions;

Operational risk cost module: based on the adjusted operating conditions, calculate the annual operational risk cost based on the cost of power abandonment, cost of purchased power, backup cost, and emergency control cost of the sending power grid under the second-level safety standard failure;

Total risk cost module: Randomly generate multiple groups of risk threshold sequences in the planning cycle, and calculate the total risk cost of each group of risk threshold sequences from the start year to the end year of the planning cycle according to the operating risk cost;

Limit sequence module: use the annual DC maximum transmittable power corresponding to the minimum total risk cost to construct the DC transmission limit sequence within the planning period.

A computer-readable storage medium storing one or more programs, the one or more programs including instructions that, when executed by a computing device, cause the computing device to perform a DC transmission limit optimization method within a planning period.

A computing device comprising one or more processors, one or more memories, and one or more programs, wherein the one or more programs are stored in the one or more memories and configured to be executed by the one or more Executed by a plurality of processors, the one or more programs include instructions for executing the method for optimizing the DC transmission limit within the planning period.

Beneficial effects achieved by the present invention: the present invention analyzes each year within the planning cycle to obtain the maximum transmittable power of direct current per year, the loss of abandoned power caused by the inability to send out full power of direct current, emergency control costs, outsourced power costs, and backup costs Calculate the unified monetization to form the operation risk cost, combine multiple sets of risk threshold sequences randomly generated, calculate the total risk cost under each risk threshold sequence, and use the annual DC maximum transmittable power corresponding to the minimum total risk cost to construct the planning cycle The internal DC transmission limit sequence, through reasonable planning of DC transmission limits, realizes the seamless connection from planning to operation, and can guide power system planners to fully consider the operation risks after DC is put into operation, so that the coordinated development of power supply-grid-DC load can be achieved.

Description of drawings

Fig. 1 is the flowchart of the method of the present invention.

Detailed ways

The present invention will be further described below in conjunction with the accompanying drawings. The following examples are only used to more clearly illustrate the technical solutions of the present invention, but cannot limit the protection scope of the present invention with this.

As shown in Figure 1, a DC transmission limit optimization method within a planning cycle includes the following steps:

Step 1. Obtain the typical operating conditions of the sending power grid every year within the planning period;

Step 2, according to the operating conditions, calculate the annual DC maximum transmittable power subject to the constraints of DC effective short-circuit ratio, AC channel power organization constraints, voltage stability constraints, and frequency stability constraints;

Step 3, according to the annual DC maximum transmittable power, calculate the cost of electricity curtailment caused by the failure of DC to send out full power, and adjust all operating conditions;

Step 4, based on the adjusted operating conditions, calculate the annual operating risk cost based on the cost of power abandonment, cost of purchased power, backup cost, and emergency control cost of the sending power grid under the failure of the second-level safety standard;

Step 5: Randomly generate multiple groups of risk threshold sequences in the planning cycle, and calculate the total risk cost of each group of risk threshold sequences from the start year to the end year of the planning cycle according to the operating risk cost;

Step 6: Use the annual DC maximum transmittable power corresponding to the minimum total risk cost to construct the DC transmission limit sequence within the planning period.

The above method is based on "decoupling-aggregation". Firstly, decoupling analysis is carried out every year in the planning cycle to obtain the maximum DC transmittable power per year, the loss of power curtailment caused by the inability to send DC at full power, emergency control costs, and outsourced power costs. , the reserve cost is uniformly monetized to form the operational risk cost, and then combined with multiple groups of randomly generated risk threshold sequences, the total risk cost under each risk threshold sequence is aggregated and calculated, and finally the annual DC maximum possible cost corresponding to the minimum total risk cost is used. Transmission power, constructing the DC transmission limit sequence within the planning period.

When acquiring the operating conditions, the probability corresponding to the operating conditions, as well as the disturbance and the disturbance probability corresponding to the production operating conditions will also be obtained accordingly.

If the sending grid is a grid without new energy, the typical operating conditions include Fengda, Fengxiao, Fengpingda, Kuda, Kuxiao and Kupingda; if the sending grid is a grid with new energy ( Generally, it includes a large amount of new energy transmission), and on the basis of the above-mentioned typical operating conditions, it also includes new energy large and new energy small.

The probability corresponding to the operating condition can be expressed as the number of hours of the operating condition in a year divided by 8760h; the disturbance is the first-level safety standard failure and the second-level safety standard stipulated in the "GB 38755-2019 Power System Safety and Stability Guidelines". For standard faults, N-1 faults in the disturbance probability can be set to 0.01 times/km, N-2 faults can be set to 0.002 times/km, DC unipolar faults can be set to 1.6 times/year, and DC bipolar faults can be set to 0.1 times/km Article. Year.

Based on the obtained operating conditions, the annual DC maximum transmittable power can be calculated, and the specific process is as follows:

21) Calculate the DC effective short-circuit ratio under all operating conditions, and obtain the maximum DC transmission power constrained by the DC effective short-circuit ratio;

When the DC effective short-circuit ratio is greater than 2 under all operating conditions, the DC transmission power is not limited;

When there is a working condition where the DC effective short-circuit ratio is less than 2, reduce the DC power in this working condition and recalculate the DC effective short-circuit ratio. When the DC effective short-circuit ratio is just equal to 2, the corresponding DC power is the DC power constrained by the short-circuit ratio Maximum transmission power P _DC ^ESCR ;

22) Calculate the transmission power of the DC near-area AC section after the AC fault occurs under all operating conditions, and obtain the maximum DC transmission power constrained by the power organization of the AC channel;

Since the DC needs to collect the power supply in the network through the AC section, it is usually necessary to check the thermal stability, transient stability, and dynamic stability of the system after the DC near-area AC N-1 and N-2 faults, when the near-area AC After N-1 and N-2 faults, if there is line overheating stability/system transient instability/system dynamic instability, reduce the transmission power of the AC section until the system is stable after AC N-1 and N-2 faults.

When the maximum transmission power P _DC ^AC of all the AC sections in the DC near area is less than the DC rated power, the maximum transmission power of the DC subject to the power organization of the AC channel is P _DC ^AC ;

23) Calculate the transient overvoltage and steady-state overvoltage limitation of the converter station and the DC near-area AC busbar under the impact of DC disturbance (including commutation failure, lockout, and restart), and obtain the maximum DC transmission power constrained by voltage stability ;

Generally speaking, the transient overvoltage shall be checked according to not exceeding the busbar voltage protection setting value of the converter station 1.3p.u./500ms, and the steady-state voltage shall be checked according to not exceeding 550kV/half an hour; Verify that the voltage of the new energy collection busbar does not exceed the new energy grid-related standards;

When the DC disturbance (including commutation failure, blocking, and restart) occurs, the transient overvoltage and steady-state overvoltage of the converter station/DC near-area AC busbar/new energy collection busbar exceed the protection setting value, that is, there is a DC fault that does not meet the requirements In the post-transient or steady-state overvoltage working condition, reduce the DC power in this working condition until the transient overvoltage and steady-state overvoltage of the converter station/DC near-area AC busbar/new energy collection busbar are within the standard after the DC disturbance. Within the range, the DC power in this working condition is the maximum DC transmission power P _DC ^voltage subject to voltage stability constraints;

24) Calculate the frequency limitation of the system under the impact of DC disturbance (including commutation failure, blocking, and restart), and obtain the maximum transmittable power of DC subject to frequency stability constraints;

Generally speaking, the highest frequency shall be checked according to the action setting value of 50.8Hz/500ms for the high-cycle cutting machine, and the lowest frequency shall not exceed the action setting value of 49Hz for low-cycle load shedding; when there is new energy in the DC near area, it shall also be checked The frequency of nuclear new energy does not exceed the new energy network-related standards; for DC with simultaneous transmission and reception, the frequency response characteristics after the failure of DC commutation at the same transmission and reception should also be checked;

Calculate the system frequency under the impact of DC disturbance (including commutation failure, lockout, and restart). For the working condition that does not meet the highest frequency or the lowest frequency after the DC fault, reduce the DC power in this working condition until the DC disturbance occurs in this working condition If the frequency is within the standard range, the DC power in this working condition is the maximum DC transmission power P _DC frequency constrained by the ^frequency ;

25) Calculate the annual DC maximum transmittable power subject to the constraints of DC effective short-circuit ratio, AC channel power organization, voltage stability and frequency stability, that is, P _DC ^max = min(P _DC ^ESCR ,P _DC ^AC ,P _DC ^voltage ,P _DC ^frequency )

According to the maximum transmittable power of DC each year, the power abandonment cost caused by the inability to send DC at full power is calculated. The specific formula is as follows:

is the maximum transmittable power of DC, and k is the unit cost of power abandonment, which can be determined by referring to the unit grid price of power sources. For example, the unit cost of power abandonment of hydropower is 227.7 yuan/MWh, and P ^j is the DC power arranged in operating condition j.

Adjust all operating conditions according to the annual DC maximum transmittable power: When adjusting all operating conditions, for operating conditions where the DC power is greater than the DC maximum transmittable power, adjust the DC power to the maximum transmittable power, and reduce the supporting power supply first contribute.

Based on the adjusted operating conditions, the annual operating risk cost is calculated, and the specific formula is:

Among them, C _risk is the operation risk cost, λ ⁱ , ω ^t are the probability of operating condition i and the corresponding disturbance probability, respectively, C _ec , C _re , and C _pur are the emergency control cost, backup cost and purchased electricity cost, respectively.

The above-mentioned random generation of risk threshold sequences in multiple sets of planning cycles, according to the operating risk cost, calculates the total risk cost of each set of risk threshold sequences from the start year to the end year of the planning cycle. The specific process is as follows:

51) Randomly generate multiple sets of risk threshold sequences within the planning cycle; wherein, the start year and end year of each set of risk threshold sequences are consistent with the start year and end year of the planning cycle, and each set of risk threshold sequences includes the planning cycle Risk thresholds for each year;

52) For each set of risk threshold series, optimize the selection of planning measures for the year in which the operating risk cost exceeds the corresponding risk threshold, until the operating risk cost is reduced to within the risk threshold, and include the planning measures in subsequent years to refresh the working conditions of subsequent years and disturbance, calculate the total cost of risk under the risk threshold sequence; among them, the total cost of risk is the accumulation of the annual operation risk cost and the cost of planning measures in the planning cycle. If no optimization selection of planning measures is made, the cost of planning measures is 0; Including new energy storage, pumped storage, SVG, lines, main transformer.

In the planning and design stage of DC, the above method considers risks such as safety and adequacy in operation and monetizes them, and considers the risk cost in operation and the economics of DC power transmission as a whole, avoiding the problems caused by single consideration of operation or planning. The DC transmission power is not coordinated with the power supply and the grid, resulting in insufficient DC carrying capacity of the grid; through reasonable planning of the DC transmission limit, the seamless connection between planning and operation can be realized, and it can guide power system planners to fully consider the operation after DC is put into operation Risks make the power supply-grid-DC load coordinated development.

A DC transmission limit optimization system within a planning cycle, characterized in that: comprising,

Those skilled in the art should understand that the embodiments of the present application may be provided as methods, systems, or computer program products. Accordingly, the present application may take the form of an entirely hardware embodiment, an entirely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present application may take the form of a computer program product embodied on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) having computer-usable program code embodied therein.

The present application is described with reference to flowcharts and/or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the present application. It should be understood that each procedure and/or block in the flowchart and/or block diagram, and a combination of procedures and/or blocks in the flowchart and/or block diagram can be realized by computer program instructions. These computer program instructions may be provided to a general purpose computer, special purpose computer, embedded processor, or processor of other programmable data processing equipment to produce a machine such that the instructions executed by the processor of the computer or other programmable data processing equipment produce a An apparatus for realizing the functions specified in one or more procedures of the flowchart and/or one or more blocks of the block diagram.

These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing apparatus to operate in a specific manner, such that the instructions stored in the computer-readable memory produce an article of manufacture comprising instruction means, the instructions The device realizes the function specified in one or more procedures of the flowchart and/or one or more blocks of the block diagram.

These computer program instructions can also be loaded onto a computer or other programmable data processing device, causing a series of operational steps to be performed on the computer or other programmable device to produce a computer-implemented process, thereby The instructions provide steps for implementing the functions specified in the flow chart or blocks of the flowchart and/or the block or blocks of the block diagrams.

The above are only embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention are included in the pending application of the present invention. within the scope of the claims.

Claims

A DC transmission limit optimization method within a planning cycle, characterized in that: comprising,

Obtain the typical operating conditions of the sending power grid every year within the planning period;

According to the operating conditions, calculate the annual DC maximum transmittable power subject to the constraints of DC effective short-circuit ratio, AC channel power organization constraints, voltage stability constraints, and frequency stability constraints;

According to the annual DC maximum transmittable power, calculate the cost of power abandonment caused by the failure of DC to send out full power, and adjust all operating conditions;

Based on the adjusted operating conditions, the annual operating risk cost is calculated according to the cost of power abandonment, the cost of purchased power, the cost of backup, and the emergency control cost of the sending power grid under the failure of the second-level safety standard;

Randomly generate multiple groups of risk threshold sequences in the planning cycle, and calculate the total risk cost under each group of risk threshold sequences from the start year to the end year of the planning cycle according to the operating risk cost;

The DC maximum transmittable power corresponding to the minimum total cost of risk is used to construct the DC transmission limit sequence within the planning period.
A DC transmission limit optimization method within a planning period according to claim 1, characterized in that: if the power grid at the sending end is a power grid without new energy transmission, the typical operating conditions include Feng Da, Feng Xiao, Feng Ping Da, Kuda, Kuxiao and Kupingda;

If the power grid at the sending end is a power grid with new energy sent, typical operating conditions include Fengda, Fengxiao, Fengpingda, Kuda, Kuxiao, Kupingda, new energy Dafa and new energy Xiaofa.
A method for optimizing DC transmission limits within a planning cycle according to claim 1, characterized in that: according to the operating conditions, the calculation is limited by the DC effective short-circuit ratio, AC channel power organization constraints, voltage stability constraints, and frequency stability constraints. The maximum transmittable power of DC, the specific process is,

Calculate the DC effective short-circuit ratio under all operating conditions to obtain the maximum DC transmission power constrained by the DC effective short-circuit ratio;

Calculate the transmission power of the DC near-area AC section after the AC fault occurs under all operating conditions, and obtain the maximum DC transmission power constrained by the power organization of the AC channel;

Calculate the transient overvoltage and steady overvoltage limitation of the converter station and the AC bus in the DC vicinity under the impact of DC disturbance, and obtain the maximum DC transmission power subject to voltage stability constraints;

Calculate the frequency limitation of the system under the impact of DC disturbance, and obtain the maximum transmittable power of DC subject to the frequency stability constraint;

Calculate the annual DC maximum transmittable power subject to the constraints of DC effective short-circuit ratio, AC channel power organization, voltage stability and frequency stability.
A DC transmission limit optimization method within a planning period according to claim 1, characterized in that: the calculation formula of power abandonment cost is:

Among them, C discard is the cost of electricity discarding, j and λ j are the operating conditions and the probability of operating conditions in which the power arranged by DC is greater than the maximum transmittable power of DC, respectively,
is the maximum transmittable power of DC, k is the unit cost of curtailment, and P j is the DC power arranged in operating condition j.
A method for optimizing DC transmission limits within a planning period according to claim 4, characterized in that: when adjusting all operating conditions, for operating conditions in which the power of the DC arrangement is greater than the maximum transmittable power of the DC, the DC power is adjusted to The maximum transmittable power, prioritizing the reduction of supporting power supply output.
A method for optimizing DC transmission limits within a planning period according to claim 1, wherein the formula for calculating the operating risk cost is:

Among them, C risk is the operation risk cost, C discard is the power abandonment cost, λ i , ω t are the operating condition i probability and the corresponding disturbance probability respectively, C ec , C re , C pur are the emergency control cost, backup cost and The cost of purchased electricity.
A method for optimizing DC transmission limits within a planning period according to claim 1, characterized in that multiple sets of risk threshold sequences within the planning period are randomly generated, and according to the operating risk cost, each set of risk threshold sequences is calculated starting from the planning period The total cost of risk from the beginning year to the end year, the specific process is,

Randomly generate multiple sets of risk threshold sequences in the planning cycle; the start year and end year of each set of risk threshold sequences are consistent with the start year and end year of the planning cycle, and each set of risk threshold sequences includes the risk threshold;

For each set of risk threshold series, optimize the selection of planning measures for the year in which the operating risk cost exceeds the corresponding risk threshold, and calculate the total risk cost under the risk threshold sequence; where the total risk cost is the annual operating risk cost and planning Measures add up in cost.
A DC transmission limit optimization system within a planning cycle, characterized in that: comprising,

Operating condition acquisition module: acquire the typical operating conditions of the sending power grid every year within the planning period;

Transmittable power module: According to the operating conditions, calculate the annual DC maximum transmittable power subject to the constraints of DC effective short-circuit ratio, AC channel power organization constraints, voltage stability constraints, and frequency stability constraints;

Abandonment cost module: According to the annual DC maximum transmittable power, calculate the electricity abandonment cost caused by the failure of DC to send out full power, and adjust all operating conditions;

Operational risk cost module: based on the adjusted operating conditions, calculate the annual operational risk cost based on the cost of power abandonment, cost of purchased power, backup cost, and emergency control cost of the sending power grid under the second-level safety standard failure;

Total risk cost module: Randomly generate multiple groups of risk threshold sequences in the planning cycle, and calculate the total risk cost of each group of risk threshold sequences from the start year to the end year of the planning cycle according to the operating risk cost;

Limit sequence module: use the annual DC maximum transmittable power corresponding to the minimum total risk cost to construct the DC transmission limit sequence within the planning period.
A computer-readable storage medium storing one or more programs, wherein the one or more programs comprise instructions which, when executed by a computing device, cause the computing device to perform the Any one of the methods described in 7.
A computing device, comprising:

one or more processors, one or more memories, and one or more programs, wherein the one or more programs are stored in the one or more memories and configured to be executed by the one or more processors, The one or more programs include instructions for performing any of the methods according to claims 1-7.