CN113890080A - Method for optimizing direct current transmission limit in planning period considering operation risk - Google Patents

Method for optimizing direct current transmission limit in planning period considering operation risk Download PDF

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CN113890080A
CN113890080A CN202110999897.3A CN202110999897A CN113890080A CN 113890080 A CN113890080 A CN 113890080A CN 202110999897 A CN202110999897 A CN 202110999897A CN 113890080 A CN113890080 A CN 113890080A
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direct current
power
cost
planning
maximum
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蔡绍荣
周泓
魏明奎
江栗
路亮
陶宇轩
沈力
王庆
梁文举
文一宇
张鹏
杨宇霄
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Southwest Branch of State Grid Corp
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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H02J3/36—Arrangements for transfer of electric power between ac networks via a high-tension dc link
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H02J3/04—Circuit arrangements for ac mains or ac distribution networks for connecting networks of the same frequency but supplied from different sources
    • H02J3/06—Controlling transfer of power between connected networks; Controlling sharing of load between connected networks
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H02J3/12—Circuit arrangements for ac mains or ac distribution networks for adjusting voltage in ac networks by changing a characteristic of the network load
    • H02J3/14—Circuit arrangements for ac mains or ac distribution networks for adjusting voltage in ac networks by changing a characteristic of the network load by switching loads on to, or off from, network, e.g. progressively balanced loading
    • H02J3/144—Demand-response operation of the power transmission or distribution network
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H02J3/24—Arrangements for preventing or reducing oscillations of power in networks
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J2203/00—Indexing scheme relating to details of circuit arrangements for AC mains or AC distribution networks
    • H02J2203/10—Power transmission or distribution systems management focussing at grid-level, e.g. load flow analysis, node profile computation, meshed network optimisation, active network management or spinning reserve management
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J2203/00—Indexing scheme relating to details of circuit arrangements for AC mains or AC distribution networks
    • H02J2203/20—Simulating, e g planning, reliability check, modelling or computer assisted design [CAD]
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
    • Y02B70/00—Technologies for an efficient end-user side electric power management and consumption
    • Y02B70/30—Systems integrating technologies related to power network operation and communication or information technologies for improving the carbon footprint of the management of residential or tertiary loads, i.e. smart grids as climate change mitigation technology in the buildings sector, including also the last stages of power distribution and the control, monitoring or operating management systems at local level
    • Y02B70/3225—Demand response systems, e.g. load shedding, peak shaving
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/60—Arrangements for transfer of electric power between AC networks or generators via a high voltage DC link [HVCD]
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y04—INFORMATION OR COMMUNICATION TECHNOLOGIES HAVING AN IMPACT ON OTHER TECHNOLOGY AREAS
    • Y04S—SYSTEMS INTEGRATING TECHNOLOGIES RELATED TO POWER NETWORK OPERATION, COMMUNICATION OR INFORMATION TECHNOLOGIES FOR IMPROVING THE ELECTRICAL POWER GENERATION, TRANSMISSION, DISTRIBUTION, MANAGEMENT OR USAGE, i.e. SMART GRIDS
    • Y04S20/00—Management or operation of end-user stationary applications or the last stages of power distribution; Controlling, monitoring or operating thereof
    • Y04S20/20—End-user application control systems
    • Y04S20/222—Demand response systems, e.g. load shedding, peak shaving

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

Abstract

The invention discloses a method for optimizing a direct current transmission limit in a planning period by considering an operation risk, and belongs to the technical field of power grid planning. Decoupling analysis is carried out on the direct current under a given grid frame every year in a planning period, the maximum transmission capacity of the direct current under the given grid frame is evaluated, the electricity abandonment loss caused by the fact that the direct current cannot be sent out at full power is transmitted, emergency control cost, outsourcing electricity cost and standby cost are unified and monetized, and risk cost of an operation layer is formed; and then randomly setting a risk threshold sequence in the planning period, optimizing planning measures when the risk cost exceeds a threshold value, and aggregating to obtain the total risk cost in the planning period under the set of threshold values. And finally traversing all threshold combinations, and when the total risk cost in the planning period is minimum, the corresponding maximum direct current transmission capacity every year is the direct current transmission limit considering the coordination of planning and operation. The method can guide the power system planning personnel to fully consider the operation risk after the direct current operation, and perfect various planning measures.

Description

Method for optimizing direct current transmission limit in planning period considering operation risk
Technical Field
The invention belongs to the technical field of power grid planning, and particularly relates to a direct current transmission limit optimization method in a planning period considering operation risks.
Background
In order to solve the structural problem of unbalanced energy resources and power load in the east and west of China, the optimized configuration capacity of the energy resources in China is improved, the advantage of ultra-high-voltage direct-current long-distance large-capacity power transmission is fully exerted, more and more direct-current projects are listed in power grid development planning, but with the adoption of the fact that the number of direct currents in each large power grid is more and more, the coupling between systems such as alternating current and direct current, direct current and new energy is tighter and tighter, the stability problems of the frequency, the voltage and the like of the power grid after the alternating current and direct current faults are aggravated, and the direct current carrying capacity of the power grid is increasingly becoming a key factor for restricting the direct current carrying capacity of the power grid.
At present, research on the dc bearing capacity is still in an exploration phase, and without a clear definition, the dc bearing capacity shall include two aspects of "dc" and "bearing capacity", where dc is an important power transmission method for power transmission, and the bearing capacity includes its own attribute, that is, the capacity of dc transmission cannot exceed a "threshold" that can be carried by a power system. For a transmitting-end power grid, from the perspective of planning, the direct-current carrying capacity is derived from energy planning and power planning, the direct-current planning serves a renewable energy development plan of a regional power grid, and when a large amount of surplus power exists in the regional power grid, direct current becomes a surplus power delivery means. In essence, the direct current bearing capacity depends on the degree of energy development, and a matching alternating current network frame follows an upgrading and transforming plan of a power supply and a direct current load planning, and the main power for driving the direct current bearing capacity to be gradually improved is the development and construction of renewable energy. Theoretically, if the new power supply and the main framework structure and other supporting projects are built in advance or synchronously, the direct current output is not limited, conversely, the power supply and the power grid can not be disconnected, the direct current planning can not be carried out, or the direct current transmission capacity can not be improved, and the source, the power grid and the direct current load are planned in a coordinated mode.
From the operation perspective, because the safety problem is checked according to N-1 mainly by considering the abundance and economy such as power and electric quantity balance, peak regulation standby and the like when planning the direct current construction, and the construction of the direct current engineering is far ahead of the construction of a main alternating current network, the direct current bearing capacity in the actual operation is generally smaller than the rated power of the direct current planning, and the method is particularly obvious in the transition period of direct current operation. When the direct current planning leads the power grid planning, the problem of small power grid and large delivery caused by large-scale direct current delivery is prominent, and the running risks such as system power balance and safety are increased, so that the direct current carrying capacity is insufficient; when the investment of power grid planning is excessive, the planned direct current can be sent out at full power, the corresponding risk cost is reduced, and the waste of infrastructure investment is caused.
Therefore, it is necessary to consider the operation risk in the planning, take the resource waste and the annual renewable energy utilization hours shortage caused by the direct current incapable of being delivered with full power into the power grid planning consideration range, realize the maximum power delivery of the direct current on the basis of the coordination of the planning and the operation, and improve the utilization hours of the direct current delivery channel.
Disclosure of Invention
Aiming at the problems in the prior art, the invention provides a method for optimizing a direct current transmission limit in a planning period by considering an operation risk, which aims to: and guiding the power system planning personnel to fully consider the operation risk after the direct current operation and perfecting various planning measures.
The technical scheme adopted by the invention is as follows:
a method for optimizing a direct current transmission limit in a planning period considering operation risks comprises the following steps:
step 1: acquiring typical operation conditions and corresponding probabilities of the conditions of a transmitting-end power grid every year in a planning period, and generating a corresponding disturbance library and a corresponding disturbance probability;
step 2: calculating the direct-current maximum transmittable power meeting the requirements of the effective short-circuit ratio, the tide organization, the voltage stability and the frequency stability of the power grid year by year;
and step 3: calculating the electricity abandoning cost caused by that the direct current cannot be sent out at full power year by year, adjusting all operating conditions according to the maximum direct current transmittable power every year, wherein the electricity abandoning cost is defined as:
Figure BDA0003231660400000021
in the formula: j. lambda [ alpha ]jOperating conditions and operating condition probabilities, P, respectively, for which the power arranged for the direct current is greater than the maximum transmittable powerjSetting the direct current power in the working condition j, wherein k is the unit cost of electricity abandonment;
and 4, step 4: on the basis of the adjusted operation condition, calculating the emergency control cost of the power grid under the second-level safety standard fault, the external electricity purchasing cost and the standby cost, and forming annual operation risk cost together with the electricity abandoning cost in the step 3;
and 5: randomly generating a plurality of groups of risk threshold value sequences from the initial year to the planning terminal year, carrying out optimization selection on planning measures when the operation risk cost exceeds the risk threshold value until the operation risk cost is reduced to be within the risk threshold value, counting the planning measures into the subsequent year, and refreshing a working condition library and a disturbance library of the subsequent year;
step 6: and counting the total risk cost in the planning period under each group of risk threshold values, wherein the total risk cost is the sum of the operation risk cost and the planning measure cost in each year in the planning period, and the maximum power capable of being transmitted by the direct current in each year corresponding to the minimum total risk cost is the direct current transmission limit sequence in the planning period.
Preferably, the disturbance library in step 1 includes a first-level safety standard fault and a second-level safety standard fault specified in the safety and stability guide rule of GB 38755 and 2019 power system; typical operation conditions of the power grid at the sending end include large, small and large power grids, and for the power grid containing a large amount of new energy, the power grid also includes the conditions of large new energy generation and small new energy generation.
Preferably, the step 2 of calculating the maximum dc transmittable power specifically includes the following steps:
step 2.1: calculating the DC effective short-circuit ratio index under all working conditions, when the DC effective short-circuit ratio is less than 2, reducing the DC power until the effective short-circuit ratio index is greater than 2, and the DC maximum transmission power constrained by the short-circuit ratio is PDC ESCR；
Step 2.2: calculating the power organization condition of the direct current near-region alternating current section after alternating current faults occur under all working conditions, and when the maximum power transmission power of all the collected alternating current sections in the direct current near region is smaller than the direct current rated power, the maximum direct current power transmission power constrained by the power organization of the alternating current channel is PDC AC；
Step 2.3: calculating transient overvoltage and steady overvoltage limiting conditions of the converter station and the direct current near-zone alternating current bus under direct current disturbance impact; for the working condition of transient state or steady state overvoltage after the direct current fault is not satisfied, the direct current power is reduced until all the voltages are in the standard range, and the maximum direct current transmission power constrained by the voltage stability is PDC voltage；
Step 2.4: calculating the limited condition of the system frequency under the impact of the direct current disturbance; for the direct current with simultaneous transmission and reception, checking the frequency response characteristic after the direct current phase commutation failure of the simultaneous transmission and reception; for maximum frequency after failing to satisfy DC fault orUnder the working condition of lowest frequency, the direct current power is reduced until the frequency is in the standard range after the fault, and the direct current maximum transmission power constrained by the frequency is PDC frequency；
Step 2.5: calculating the maximum direct current transmissible power which simultaneously meets the effective short circuit ratio, the tide organization, the voltage stability and the frequency stability under all working conditions as follows:
PDC max＝min(PDC ESCR,PDC AC,PDC voltage,PDC frequency)。
preferably, in step 2.3, the transient overvoltage is checked according to a condition that the transient overvoltage does not exceed a bus voltage protection fixed value of the converter station by 1.3p.u./500ms, the steady-state voltage is checked according to a condition that the steady-state voltage does not exceed 550 kV/half an hour, and when new energy exists in a direct current near region, the new energy collection bus voltage is checked to not exceed a new energy grid-related standard.
Preferably, in step 2.4, the highest frequency is checked according to the action fixed value of the generator not exceeding the high-cycle generator to be 50.8Hz/500ms, and the lowest frequency is checked according to the action fixed value of the generator not exceeding the low-cycle deloading to be 49 Hz; when new energy exists in the direct current near area, the frequency of the new energy does not exceed the new energy grid-related standard.
Preferably, in step 3, when all the operating conditions are adjusted according to the maximum dc transmittable power per year, for the operating condition that the power scheduled for dc is greater than the maximum transmittable power, the dc power needs to be adjusted to the maximum transmittable power, and the output of the matching power source is preferentially reduced.
Preferably, the emergency control cost C in step 4ecThe system comprises the costs of cutting off, modulating direct current, cutting off load and the like under all the alternating current and direct current faults of the system, and the annual operation risk cost is as follows:
Figure BDA0003231660400000031
in the formula: lambda [ alpha ]i、wtRespectively, operating mode probability and fault probability, Cre、CpurThe standby cost and the outsourcing electricity cost are respectively corresponding to the working condition.
Preferably, the planning measures in step 5 include newly building energy storage, pumping storage, SVG, lines and main transformers.
In summary, due to the adoption of the technical scheme, the invention has the beneficial effects that:
by adopting the method, the operation risk of the power system planning personnel after the direct current operation can be guided to fully consider, various planning measures are perfected, the current power supply and power grid construction just meets the direct current output capacity, the investment waste is not caused, and the over-high risk of the power system caused by the limited direct current output is avoided.
Drawings
The invention will now be described, by way of example, with reference to the accompanying drawings, in which:
FIG. 1 is a flow chart of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are only a part of the embodiments of the present application, and not all the embodiments. The components of the embodiments of the present application, generally described and illustrated in the figures herein, can be arranged and designed in a wide variety of different configurations. Thus, the following detailed description of the embodiments of the present application, presented in the accompanying drawings, is not intended to limit the scope of the claimed application, but is merely representative of selected embodiments of the application. All other embodiments, which can be derived by a person skilled in the art from the embodiments of the present application without making any creative effort, shall fall within the protection scope of the present application.
The present invention will be described in detail with reference to fig. 1.
A method for optimizing a direct current transmission limit in a planning period considering operation risks comprises the following steps:
step 1: acquiring typical operating conditions and corresponding probabilities of the operating conditions of a transmitting-end power grid every year in a planning period; generating corresponding disturbance and disturbance probability, wherein the disturbance library comprises a first-level safety standard fault and a second-level safety standard fault specified in GB 38755-2019 electric power system safety and stability guide rule;
typical operation conditions of a sending-end power grid include large, small and large, and for a power grid containing a large amount of new energy to be sent out, the typical operation conditions also include new energy large sending and new energy small sending conditions on the basis of the typical mode;
probability lambda corresponding to working condition iiWhich can be expressed as the number of hours that the operating condition occurs in one year divided by 8760 hours;
the probability of disturbance may be 0.01N-1 fault/km, 0.002N-2 fault/km, 1.6 DC monopolar faults/one year, and 0.1 DC bipolar faults/one year.
Step 2: calculating the maximum direct-current transmissible power which meets the requirements of the effective short-circuit ratio, the tide organization, the voltage stability and the frequency stability of the power grid, and specifically comprising the following steps:
step 2.1: calculating the DC effective short-circuit ratio index under all working conditions, when the DC effective short-circuit ratio is less than 2, reducing the DC power until the effective short-circuit ratio index is greater than 2, and the DC maximum transmission power constrained by the short-circuit ratio is PDC ESCR；
Step 2.2: calculating the power organization condition of the direct current near-region alternating current section after alternating current faults occur under all working conditions, and when the maximum power transmission power of all the collected alternating current sections in the direct current near region is smaller than the direct current rated power, the maximum direct current power transmission power constrained by the power organization of the alternating current channel is PDC AC；
Step 2.3: and (2) calculating transient overvoltage and steady-state overvoltage limiting conditions of the converter station and the direct-current near-zone alternating-current bus under the impact of direct-current disturbance (including commutation failure, locking and restarting), wherein generally, the transient overvoltage is checked according to the condition that the transient overvoltage does not exceed the bus voltage protection fixed value of the converter station by 1.3p.u./500ms, and the steady-state voltage is checked according to the condition that the steady-state voltage does not exceed 550 kV/half hour. When new energy exists in the direct current near area, the voltage of a new energy collection bus is not more than the new energy grid-related standard to be checked. For the working condition of transient state or steady state overvoltage after not meeting the DC fault, reducing the DC power until all the voltages are in the standard range and are restrained by the voltage stabilityThe maximum DC transmission power is PDC voltage；
Step 2.4: calculating the limited condition of the system frequency under the impact of direct current disturbance (including commutation failure, locking and restarting), generally speaking, checking that the highest frequency does not exceed the action fixed value of a high-frequency tripping machine by 50.8Hz/500ms, and the lowest frequency does not exceed the action fixed value of a low-frequency load shedding machine by 49 Hz; when new energy exists in a direct current near area, the new energy frequency is not more than the new energy grid-related standard to be checked. For the direct current with simultaneous transmission and reception, the frequency response characteristic after the direct current commutation failure of the simultaneous transmission and reception should be checked. For the working condition that the highest frequency or the lowest frequency after the direct current fault is not satisfied, the direct current power is reduced until the frequency after the fault is within the standard range, and the direct current maximum transmission power constrained by the frequency is PDC frequency；
Step 2.5: calculating the maximum direct current transmissible power which simultaneously meets the effective short circuit ratio, the tide organization, the voltage stability and the frequency stability under all working conditions as follows:
PDC max＝min(PDC ESCR,PDC AC,PDC voltage,PDC frequency)
and step 3: the electricity abandoning cost caused by the fact that the direct current cannot be sent out in full power is counted, all operation conditions are adjusted according to the maximum power which can be transmitted in the direct current every year, and the electricity abandoning cost is defined as:
Figure BDA0003231660400000051
in the formula: j. lambda [ alpha ]jOperating conditions and operating condition probabilities, P, respectively, for which the power arranged for the direct current is greater than the maximum transmittable powerjFor the direct current power arranged in the working condition j, k is the unit cost of electricity abandonment, and the unit cost of electricity abandonment of the power supply can be made by referring to the unit grid electricity price of the power supply, for example, the unit cost of electricity abandonment of hydropower is 227.7 yuan/MWh.
When all the operating conditions are adjusted according to the maximum DC transmissible power every year, the DC power needs to be adjusted to the maximum transmissible power for the operating conditions that the DC scheduled power is larger than the maximum transmissible power, and the output of the matched power supply is preferentially reduced.
And 4, step 4: and calculating the emergency control cost of the power grid under the second-level safety standard fault, the external electricity purchasing cost and the standby cost based on the adjusted operation working condition, and forming annual operation risk cost together with the electricity abandoning cost.
Emergency control cost CecThe system comprises the costs of cutting off, modulating direct current, cutting off load and the like under all the alternating current and direct current faults of the system, and the annual operation risk cost is as follows:
Figure BDA0003231660400000061
in the formula: lambda [ alpha ]i、wtRespectively, operating mode probability and fault probability, Cre、CpurThe standby cost and the outsourcing electricity cost are respectively corresponding to the working condition.
And 5: randomly generating a plurality of groups of risk threshold value sequences from the initial year to the planning terminal year, carrying out optimization selection on planning measures when the operation risk cost exceeds the threshold value until the operation risk cost is reduced to be within the risk threshold value, counting the planning measures into the subsequent year, and refreshing a working condition base and a disturbance base of the subsequent year. The planning measures comprise newly building energy storage, pumped storage, SVG, circuits and main transformers;
step 6: and (4) counting the total risk cost in the planning period under each group of risk thresholds, wherein the total risk cost is the sum of the operation risk cost and the planning measure cost in each year in the planning period. And the maximum annual direct current transmittable power corresponding to the minimum risk total cost is the direct current transmission limit sequence in the planning period.
The above-mentioned embodiments only express the specific embodiments of the present application, and the description thereof is more specific and detailed, but not construed as limiting the scope of the present application. It should be noted that, for those skilled in the art, without departing from the technical idea of the present application, several changes and modifications can be made, which are all within the protection scope of the present application.

Claims (8)

1. A method for optimizing a direct current transmission limit in a planning period considering an operation risk is characterized by comprising the following steps:
step 1: acquiring typical operation conditions and corresponding probabilities of the conditions of a transmitting-end power grid every year in a planning period, and generating a corresponding disturbance library and a corresponding disturbance probability;
step 2: calculating the direct-current maximum transmittable power meeting the requirements of the effective short-circuit ratio, the tide organization, the voltage stability and the frequency stability of the power grid year by year;
and step 3: calculating the electricity abandoning cost caused by that the direct current cannot be sent out at full power year by year, adjusting all operating conditions according to the maximum direct current transmittable power every year, wherein the electricity abandoning cost is defined as:
Figure FDA0003231660390000011
in the formula: j. lambda [ alpha ]jOperating conditions and operating condition probabilities, P, respectively, for which the power arranged for the direct current is greater than the maximum transmittable powerjSetting the direct current power in the working condition j, wherein k is the unit cost of electricity abandonment; pDC maxThe direct current maximum transmittable power can simultaneously meet the requirements of effective short circuit ratio, tide organization, voltage stability and frequency stability under all working conditions;
and 4, step 4: on the basis of the adjusted operation condition, calculating the emergency control cost of the power grid under the second-level safety standard fault, the external electricity purchasing cost and the standby cost, and forming annual operation risk cost together with the electricity abandoning cost in the step 3;
and 5: randomly generating a plurality of groups of risk threshold value sequences from the initial year to the planning terminal year, carrying out optimization selection on planning measures when the operation risk cost exceeds the risk threshold value until the operation risk cost is reduced to be within the risk threshold value, counting the planning measures into the subsequent year, and refreshing a working condition library and a disturbance library of the subsequent year;
step 6: and counting the total risk cost in the planning period under each group of risk threshold values, wherein the total risk cost is the sum of the operation risk cost and the planning measure cost in each year in the planning period, and the maximum power capable of being transmitted by the direct current in each year corresponding to the minimum total risk cost is the direct current transmission limit sequence in the planning period.
2. The method as claimed in claim 1, wherein the disturbance library in step 1 includes a first level safety standard fault and a second level safety standard fault specified in GB 38755 and 2019 power system safety and stability guideline; typical operation conditions of the power grid at the sending end include large, small and large power grids, and for the power grid containing a large amount of new energy, the power grid also includes the conditions of large new energy generation and small new energy generation.
3. The method according to claim 1, wherein the step 2 of calculating the maximum dc power that can be transmitted specifically includes the following steps:
step 2.1: calculating the DC effective short-circuit ratio index under all working conditions, when the DC effective short-circuit ratio is less than 2, reducing the DC power until the effective short-circuit ratio index is greater than 2, and the DC maximum transmission power constrained by the short-circuit ratio is PDC ESCR；
Step 2.2: calculating the power organization condition of the direct current near-region alternating current section after alternating current faults occur under all working conditions, and when the maximum power transmission power of all the collected alternating current sections in the direct current near region is smaller than the direct current rated power, the maximum direct current power transmission power constrained by the power organization of the alternating current channel is PDC AC；
Step 2.3: calculating transient overvoltage and steady overvoltage limiting conditions of the converter station and the direct current near-zone alternating current bus under direct current disturbance impact; for the working condition of transient state or steady state overvoltage after the direct current fault is not satisfied, the direct current power is reduced until all the voltages are in the standard range, and the maximum direct current transmission power constrained by the voltage stability is PDC voltage；
Step 2.4: calculating the limited condition of the system frequency under the impact of the direct current disturbance; checking the simultaneous transmission and reception for the direct current with simultaneous transmission and receptionFrequency response characteristics after direct current commutation failure; for the working condition that the highest frequency or the lowest frequency after the direct current fault is not satisfied, the direct current power is reduced until the frequency after the fault is within the standard range, and the direct current maximum transmission power constrained by the frequency is PDC frequency；
Step 2.5: calculating the maximum direct current transmissible power which simultaneously meets the effective short circuit ratio, the tide organization, the voltage stability and the frequency stability under all working conditions as follows:
PDC max＝min(PDC ESCR,PDC AC,PDC voltage,PDC frequency)。
4. the method for optimizing the direct current transmission limit in the planning period considering the operation risk as claimed in claim 3, wherein in step 2.3, the transient overvoltage is checked according to the condition that the transient overvoltage does not exceed the bus voltage protection fixed value of the converter station by 1.3p.u./500ms, the steady-state voltage is checked according to the condition that the steady-state voltage does not exceed 550 kV/half hour, and when new energy exists in a direct current near zone, the new energy convergence bus voltage is checked not to exceed the new energy grid-related standard.
5. The method for optimizing the direct current transmission limit in the planning period considering the operation risk as claimed in claim 3, wherein in step 2.4, the highest frequency is checked according to the action setting value of the generator not exceeding the high-cycle cutting machine being 50.8Hz/500ms, and the lowest frequency is checked according to the action setting value of the generator not exceeding the low-cycle unloading being 49 Hz; when new energy exists in the direct current near area, the frequency of the new energy does not exceed the new energy grid-related standard.
6. The method according to claim 1, wherein in step 3, when all the operating conditions are adjusted according to the annual maximum dc transferable power, for the operating condition that the dc scheduled power is larger than the maximum transferable power, the dc power needs to be adjusted to the maximum transferable power, and the output of the mating power source is preferentially reduced.
7. The method as claimed in claim 1, wherein the emergency control cost C in step 4 is the dc transmission limit optimization method in the planning cycle considering the operation riskecThe system comprises the costs of cutting off, modulating direct current, cutting off load and the like under all the alternating current and direct current faults of the system, and the annual operation risk cost is as follows:
Figure FDA0003231660390000021
in the formula: lambda [ alpha ]i、wtRespectively, operating mode probability and fault probability, Cre、CpurThe standby cost and the outsourcing electricity cost are respectively corresponding to the working condition.
8. The method according to claim 1, wherein the planning measures in step 5 include new energy storage, pumped storage, SVG, line, and main transformer.
CN202110999897.3A 2021-08-26 2021-08-26 Method for optimizing direct current transmission limit in planning period considering operation risk Pending CN113890080A (en)

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US20150310366A1 (en) * 2012-11-09 2015-10-29 Tianjin University Security region based security-constrained economic dispatching method
CN105449669A (en) * 2015-12-04 2016-03-30 国网山东省电力公司电力科学研究院 Power system emergency control optimization method considering power transmission line temperature characteristic
CN108899904A (en) * 2018-08-30 2018-11-27 山东大学 A kind of alternating current-direct current large power grid cascading failure method for fast searching and system
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