A method and system for assessing the renewable energy carrying capacity of a provincial power grid.

Abstract

This invention discloses a method and system for assessing the renewable energy carrying capacity of a provincial power grid, comprising: determining a first minimum operating capacity of thermal power units in the provincial power grid considering frequency stability constraints; determining a second minimum operating capacity of thermal power units in the provincial power grid considering voltage stability constraints; dividing the provincial power grid into multiple zones based on tie lines; calculating the minimum operating capacity of thermal power units in each zone according to the first and second minimum operating capacities; setting a renewable energy absorption rate; and performing power balance calculations through production simulation based on the renewable energy absorption rate and the minimum operating capacity of thermal power units in each zone to determine whether the renewable energy absorption rate of each zone reaches a limit. If it reaches the limit, the total renewable energy installed capacity of each zone is calculated and determined as the renewable energy carrying capacity of the provincial power grid. By balancing safety and balance constraints, the renewable energy scale that the provincial power grid can carry can be accurately assessed, improving system security.

Description

Technical Field

[0001] This invention relates to the field of power system planning, and specifically to a method and system for assessing the capacity of new energy carrying capacity in a provincial power grid. Background Technology

[0002] Due to the nonlinearity, robustness, and real-time balance characteristics of power systems, the grid connection and initial planning of new renewable energy installations need to address two issues: first, the supply-demand balance problem, ensuring that electricity and power supply meet load demands and preventing power shortages; and second, the system security problem, ensuring that renewable energy grid connection does not affect the security of the power system. The supply-demand balance problem can be solved through an 8760-hour power balance analysis; the security problem requires considering the renewable energy carrying capacity under constraints of power angle, voltage, and frequency stability. Since security and balance have different time scales and analysis methods, and balance and stability characteristics are coupled, they need to be considered together.

[0003] Provincial power grids are part of regional power grids, and their safety and stability characteristics are closely related to those of the regional power grids, but they also have specific characteristics. Currently, there are some methods for analyzing the carrying capacity of new energy sources, but they suffer from incomplete considerations. For example, they only consider frequency stability without simultaneously taking into account power angle, voltage, and frequency stability constraints; they only consider the regional power grid without specifying how to analyze the provincial power grid, which is part of the regional power grid; and they do not consider the impact of critical tie-line constraints on the carrying capacity of new energy sources. Summary of the Invention

[0004] To overcome the shortcomings of the prior art, this invention provides a method for assessing the renewable energy carrying capacity of a provincial power grid, comprising:

[0005] Determine the first minimum operating capacity of thermal power units in the provincial power grid, taking frequency stability constraints into account;

[0006] Determine the second minimum operating capacity of thermal power units in the provincial power grid, taking voltage stability constraints into account;

[0007] Based on the tie line, the provincial power grid is divided into multiple zones; the minimum operating capacity of thermal power units in each zone is calculated according to the first minimum operating capacity and the second minimum operating capacity.

[0008] A renewable energy absorption rate is set. Based on the renewable energy absorption rate and the minimum operating capacity of thermal power units in each zone, power balance calculation is performed through production simulation to determine whether the renewable energy absorption rate of each zone has reached the limit. If the limit is reached, the sum of the renewable energy installed capacity of each zone is determined as the renewable energy carrying capacity of the provincial power grid.

[0009] Furthermore, the first minimum operating capacity of thermal power units in the provincial power grid, considering frequency stability constraints, is determined, including:

[0010] Collect the installed capacity P of conventional generating units in provincial power grids RUN Including thermal power units P GN Hydropower unit P HN Gas turbine unit P NN Nuclear power unit P NU ;

[0011] Collect the conventional installed capacity of the regional power grids under the jurisdiction of the provincial power grid. Information such as DC sending and receiving ends and transmission capacity is used to classify DC lines within the regional power grid that meet the "same sending and receiving end" requirement into "same sending and receiving" DC groups.

[0012] The system inertia requirement for a provincial power grid constrained by commutation failure of a DC transmission and reception group is as follows:

[0013]

[0014] Among them: W k For the regional power grid inertia requirements, P DCi Let I be the capacity of the i-th simultaneous DC transmission and reception line, I be the total number of simultaneous DC transmission and reception lines, Δf be the system steady-state frequency deviation, and f be the frequency of the line. N The system's rated frequency is given by Δt, which represents the duration of continuous commutation failures in the same DC power supply and receiving circuits.

[0015] Based on the conventional installed capacity P of the provincial power grid RUN The installed capacity of conventional generating units in the regional power grids under the jurisdiction of provincial power grids Based on the system inertia requirement, the minimum thermal power inertia requirement W of the provincial power grid is calculated according to formula (2). p According to formula (3), the capacity P of the provincial power grid thermal power units that meet the thermal power inertia requirements is calculated. GNj According to formula (4), the first minimum starting capacity P of the thermal power unit that satisfies the frequency stability constraint after the fault of simultaneous power supply and reception is calculated. GNttmin :

[0016]

[0017] Among them: W HN W represents the inertia of hydropower units in the provincial power grid. NN For the inertia of the gas turbine unit in the provincial power grid, W SN For the inertia of the provincial power grid solar thermal power unit, T j Let P be the rotor inertia time constant of the j-th generator. GNj Let J be the installed capacity of the j-th generator, and J be the number of thermal power units required to meet the inertia requirement.

[0018] Collect the sending end point, receiving end point, DC type, DC rated power and grid structure of the provincial power grid DC. If the number of substations connected between two DC converter stations does not exceed 4, the DC will be divided into DC groups with the same sending end or the same receiving end.

[0019] Calculate the thermal power plant operating capacity P that satisfies the frequency stability constraint after a DC group fault at the same sending or receiving end. GNsmin ;

[0020] The first minimum operating capacity P of thermal power units in provincial power grids considering frequency stability constraints GNmin for

[0021] P GNmin =max(P GNttmin ,P GNsmin (5).

[0022] Furthermore, the thermal power plant operating capacity P that satisfies the frequency stability constraint after a DC group fault at the same sending or receiving end is calculated. GNsmin ,include:

[0023] Calculate the provincial power grid inertia W that satisfies the frequency stability constraint after a DC group fault at the same sending or receiving end. k2 ,

[0024]

[0025] Where: Δt 常 For the conventional DC blocking duration at the same sending or receiving end, Δt 柔 For the duration of flexible DC blocking at the same sending or receiving end, P DCa P represents the power loss of the conventional DC blocking at the a-th sending or receiving end. DCb Let A be the power loss of the flexible DC blocking at the b-th sending or receiving end, and let B be the total number of conventional DC lines at the sending or receiving end and the total number of flexible DC lines at the sending or receiving end.

[0026] According to the provincial power grid inertia W k2 Calculate the provincial power grid inertia P that satisfies the frequency stability constraint after a DC group fault at the same sending or receiving end. GNsj ,

[0027]

[0028] Calculate the first minimum operating capacity P of a thermal power unit that satisfies the frequency stability constraint after a DC group fault at the same sending or receiving end. GNsmin ,

[0029]

[0030] Furthermore, the second minimum operating capacity of thermal power units in the provincial power grid, considering voltage stability constraints, is determined, including:

[0031] Identify the thermal power units that can be shut down among the DC-supported thermal power units in the DC near-area of ​​the provincial power grid;

[0032] Calculate the voltage change ΔU on the bus connected to the shut-down unit in the event of a DC fault, DC group commutation failure, or the failure of the largest single generator to take off. ij ,

[0033] ΔU ij =|U' ij -U ij | (9)

[0034] Among them, U' ij U represents the voltage value of the busbar connected to the j-th power plant after the i-th fault. ij The voltage value of the busbar connected to the j-th power plant before the i-th fault;

[0035] The contribution rate index V of thermal power units to system voltage is calculated after a DC fault, a DC group commutation failure, or a single generator of the largest capacity is taken out of service. j ,

[0036]

[0037] According to V j The value is to sort the thermal power plants from smallest to largest to form a sequence of thermal power units that can be shut down.

[0038] Based on the shutdown sequence of thermal power units, each unit is shut down sequentially until the maximum voltage change at the node or the DC multi-infeed short-circuit ratio reaches a set threshold. The total capacity of the thermal power units at this point is taken as the second minimum operating capacity P of the thermal power units that meets the voltage stability constraint. U min ,

[0039]

[0040] Furthermore, based on the tie lines, the provincial power grid is divided into multiple zones, including:

[0041] Based on the maximum power limit of the critical tie line, the provincial power grid is divided into K zones, so that each zone is connected by the critical tie line.

[0042] Furthermore, based on the first minimum operating capacity and the second minimum operating capacity, the minimum operating capacity of the thermal power units in each zone is calculated, including:

[0043] Calculate the minimum operating capacity P of thermal power units in each zone. G min The specific formula is:

[0044] P G min =max(P U min ,P GNmin (12)

[0045] The minimum operating capacity P of thermal power units G min The specific formula for allocating to each partition is as follows:

[0046]

[0047] P Gk P represents the minimum operating capacity of thermal power plants in the k-th zone; RUN k Let be the standard assembly capacity of the k-th partition.

[0048] Furthermore, after determining whether the renewable energy absorption rate of each zone has reached the limit, the process also includes:

[0049] If the limit is not reached, the installed capacity of new energy in each zone will be increased;

[0050] If the limit is exceeded, the installed capacity of new energy in each zone will be reduced.

[0051] This invention also provides a system for confirming the capacity of new energy carrying capacity in provincial power grids, comprising:

[0052] The first minimum operating capacity determination module is used to determine the first minimum operating capacity of thermal power units in the provincial power grid considering frequency stability constraints.

[0053] The second minimum operating capacity determination module is used to determine the second minimum operating capacity of thermal power units in the provincial power grid considering voltage stability constraints.

[0054] The zone capacity calculation module is used to divide the provincial power grid into multiple zones based on tie lines; and to calculate the minimum operating capacity of thermal power units in each zone according to the first minimum operating capacity and the second minimum operating capacity.

[0055] The carrying capacity determination module is used to perform power balance calculations through production simulation based on the set renewable energy absorption rate and the minimum operating capacity of thermal power units in each zone. It determines whether the renewable energy absorption rate of each zone has reached the limit. If the limit has been reached, the total renewable energy installed capacity of each zone is determined as the renewable energy carrying capacity of the provincial power grid.

[0056] Furthermore, the partition capacity calculation module includes:

[0057] The minimum capacity calculation submodule for each zone is used to calculate the minimum operating capacity P of the thermal power units in each zone. G min The specific formula is as follows:

[0058] PG min =max(P U min ,P GNmin )

[0059] The capacity allocation submodule is used to allocate the minimum operating capacity P of the thermal power unit. G min The specific formula for allocating to each partition is as follows:

[0060]

[0061] P Gk P represents the minimum operating capacity of thermal power plants in the k-th zone; RUN k Let be the standard assembly capacity of the k-th partition.

[0062] Furthermore, the load-bearing capacity determination module also includes:

[0063] If the limit is not reached, the installed capacity of new energy in each zone will be increased;

[0064] If the limit is exceeded, the installed capacity of new energy in each zone will be reduced.

[0065] The present invention also provides a computer-readable storage medium having a computer program stored thereon, wherein the computer program, when executed by a processor, implements the steps of the method as described in any one of the preceding claims.

[0066] The present invention provides a method and system for evaluating the capacity of a provincial power grid to support new energy sources. It takes into account voltage stability, frequency stability and balance constraints, and can accurately evaluate the capacity of a provincial power grid to support new energy sources. Attached Figure Description

[0067] Figure 1 This is a flowchart illustrating a method for assessing the capacity of new energy carrying capacity in a provincial power grid, as provided by this invention.

[0068] Figure 2 This invention relates to a flowchart of a method for calculating the renewable energy carrying capacity of a provincial power grid, taking into account safety and balance constraints.

[0069] Figure 3 This invention relates to a flowchart of the minimum operating capacity of thermal power plants in a provincial power grid, taking into account voltage stability constraints.

[0070] Figure 4 This invention relates to AC and DC power transmission curves that take into account the minimum start-up constraints of thermal power plants;

[0071] Figure 5 This invention relates to the output curves of conventional generating units and new energy sources;

[0072] Figure 6 This invention relates to the curtailment curve of renewable energy in provincial power grids;

[0073] Figure 7 This is a schematic diagram of the structure of an assessment system for the renewable energy carrying capacity of a provincial power grid, provided in an embodiment of the present invention. Detailed Implementation

[0074] Numerous specific details are set forth in the following description to provide a full understanding of the invention. However, the invention can be practiced in many other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0075] Example 1

[0076] Figure 1 The present invention provides a method for assessing the renewable energy carrying capacity of a provincial power grid, the method comprising the following steps:

[0077] Step S101: Determine the first minimum operating capacity of thermal power units in the provincial power grid, taking into account frequency stability constraints.

[0078] Collect the capacity P of conventional equipment in the provincial power grid RUN Including thermal power units P GN Hydropower unit P HN Gas turbine unit P NN ;

[0079] Collect the conventional installed capacity of the power grid in the region where the provincial power grid is located. Collect information on the DC power grid in the region, including DC capacity and DC landing points.

[0080] Analyze the situation of simultaneous transmission and reception of all DC lines in the regional power grid of a provincial power grid. If the sending end and receiving end of some DC lines belong to the same regional power grid, then these DC lines belong to the "simultaneous transmission and reception" DC group.

[0081] The system inertia requirement for a provincial power grid constrained by commutation failure of a DC transmission and reception group is as follows:

[0082]

[0083] Among them: W k For the regional power grid inertia requirements, P DCi Let I be the capacity of the i-th simultaneous DC transmission and reception line, I be the total number of simultaneous DC transmission and reception lines, Δf be the system steady-state frequency deviation, and f be the frequency of the line. N The system's rated frequency is given by Δt, which represents the duration of continuous commutation failures in the same DC power supply and receiving circuits.

[0084] Following the principle of effectively utilizing hydropower and nuclear power as green energy sources, the minimum thermal power inertia requirement of the provincial power grid is calculated according to formula (2), and the thermal power units of the provincial power grid that meet the frequency stability constraints are calculated according to formula (3). The first minimum operating capacity P of the thermal power units that meet the frequency stability constraints is calculated according to formula (4). GNttmin :

[0085]

[0086] Among them: W HN W represents the inertia of hydropower units in the provincial power grid. NN For the inertia of the gas turbine unit in the provincial power grid, W SN For the inertia of the provincial power grid solar thermal power unit, T j Let P be the rotor inertia time constant of the j-th generator. GNj Let J be the installed capacity of the j-th generator, and J be the number of thermal power units required to meet the inertia requirement.

[0087] Collect the sending-end and receiving-end points, DC types, rated DC power, and grid structure of the provincial power grid DC. If the number of substations connected between two DC converter stations does not exceed four, the DC is divided into DC groups with the same sending end or the same receiving end. If a fault exists, it may cause an accident in which the "same sending end" or "same receiving end" DC groups experience power loss simultaneously. Calculate the provincial power grid inertia requirement that meets the frequency stability constraint after a fault in the "same sending end" or "same receiving end" DC group according to formula (6).

[0088]

[0089] Where, Δt 常 For the duration of conventional DC blocking at the "same-send end", Δt 柔 For the duration of flexible DC blocking at the "same sending end", P DCa P represents the power loss of the conventional DC blocking at the a-th "co-sending end". DCb Let A be the power loss of the flexible DC blocking at the b-th "same-send end", A be the total number of conventional DC lines at the "same-send end", and B be the total number of flexible DC lines at the "same-send end".

[0090] Calculate the capacity P of the provincial power grid thermal power units that meet the frequency stability constraint after a DC group fault at the "same sending end" according to formula (7). GNsj .

[0091]

[0092] The minimum start-up capacity P of thermal power plants that meet the frequency stability constraint after a DC group fault at the "same sending end" is calculated according to formula (8). GNsmin .

[0093]

[0094] The first minimum operating capacity P of thermal power units in provincial power grids considering frequency stability constraints GNmin for

[0095] P GN min =max(P GNtt min ,P GNs min ) (5)

[0096] Step S102: Determine the second minimum operating capacity of thermal power units in the provincial power grid, taking into account voltage stability constraints.

[0097] like Figure 3 As shown, the multi-infeed short-circuit ratio of DC in the calculation system is calculated. If the multi-infeed short-circuit ratio of a certain DC is lower than a preset threshold, voltage support equipment, such as synchronous condenser or SVG equipment, is added near that DC until the multi-infeed short-circuit ratio of the DC reaches the preset threshold.

[0098] Statistics are compiled on thermal power units in the DC near-area of ​​the provincial power grid. These units and DC-supported thermal power units with a DC multi-infeed short-circuit ratio higher than a preset threshold are classified as non-shutdown units; the remaining thermal power units in the system are shut-down units.

[0099] Calculate the voltage change ΔU on the bus connected to the shut-down unit in the event of a DC fault, DC group commutation failure, or the failure of the largest single generator to take off. ij ,

[0100] ΔU ij =|U' ij -U ij | (9)

[0101] Among them, U' ij U represents the voltage value of the busbar connected to the j-th power plant after the i-th fault. ij The voltage value of the busbar connected to the j-th power plant before the i-th fault;

[0102] The contribution rate index V of thermal power units to system voltage is calculated after a DC fault, a DC group commutation failure, or a single generator of the largest capacity is taken out of service. j ,

[0103]

[0104] According to V j The value is to sort the thermal power plants from smallest to largest to form a sequence of thermal power units that can be shut down.

[0105] Based on the shutdown sequence of thermal power units, each unit is shut down sequentially until the maximum voltage change at the node or the DC multi-infeed short-circuit ratio reaches a set threshold. The total capacity of the thermal power units at this point is taken as the second minimum operating capacity P of the thermal power units that meets the voltage stability constraint. U min ,

[0106]

[0107] Step S103: Based on the tie line, the provincial power grid is divided into multiple zones; the minimum operating capacity of thermal power units in each zone is calculated according to the first minimum operating capacity and the second minimum operating capacity.

[0108] Based on the maximum power limit of the critical tie line, the provincial power grid is divided into K zones, so that each zone is connected by the critical tie line and the power exchange between subsequent zones does not exceed the tie line limit.

[0109] Based on historical data, the predicted active power P of the load was collected for 8760 consecutive hours. L (t), inter-regional DC power prediction value P D (t), initial value of new energy grid connection scale, and predicted value sequence of active power of wind turbine units P. W (t), the predicted active power sequence P of the photovoltaic unit S (t) superimposes the load curves, load reserves, emergency reserve capacity, DC transmission, and new energy output of each zone onto the load curve.

[0110] Collect information on the installed capacity and maintenance schedules of conventional thermal power units, hydropower units, and gas turbine units.

[0111] Collect the single-unit capacity and duration of energy storage devices.

[0112] The minimum operating capacity P of the provincial power grid thermal power units is set according to formula (12). G min .

[0113] P G min =max(P U min ,P GNmin (12)

[0114] The minimum operating capacity of thermal power units is allocated to each zone according to formula (13).

[0115]

[0116] Step S104: Set the renewable energy absorption rate. Based on the renewable energy absorption rate and the minimum operating capacity of thermal power units in each zone, determine whether the renewable energy absorption rate of each zone has reached the limit. If it has reached the limit, the sum of the renewable energy installed capacity of each zone is determined as the renewable energy carrying capacity of the provincial power grid.

[0117] Set the renewable energy consumption rate R N Production simulation calculations are performed. Based on the new energy absorption rate and the minimum operating capacity of thermal power units in each zone, it is determined whether the new energy absorption rate of each zone has reached the limit. If it has reached the limit, the sum of the new energy installed capacity of each zone is determined as the carrying capacity of new energy in the provincial power grid. If it has not reached the limit, the new energy installed capacity of each zone is increased. If it exceeds the limit, the new energy installed capacity of each zone is reduced.

[0118] Example 2

[0119] according to Figure 2 The flowchart shown illustrates the calculation method for determining the renewable energy carrying capacity of a provincial power grid. The specific process is as follows:

[0120] (1) Minimum system startup capacity considering frequency stability constraints

[0121] A certain provincial power grid has a total load of 27.1 million kilowatts and a total electricity consumption of 190 billion kilowatt-hours; the installed capacity of new energy sources will reach 103 million kilowatts, including 49.61 million kilowatts of wind power and 53.72 million kilowatts of photovoltaic power; the installed capacity of conventional power sources will be 50.188 million kilowatts, including 40.278 million kilowatts of coal power and 9.85 million kilowatts of hydropower; the proportion of new energy installed capacity will reach 67.0% (102 million kilowatts).

[0122] The total installed capacity of conventional power sources in the region covered by this provincial power grid is 269.8 GW, and the installed capacity of newly generated power sources is 149 GW, including 73,000 MW of new energy, 0 MW of nuclear power, 2,600 MW of pumped storage, 64,750 MW of coal power and 170 MW of gas power.

[0123] The regional power grid transmits 14 DC lines. The maximum DC power disturbance the system can withstand is 48GW. The frequency deviation under the continuous commutation failure disturbance is close to the 0.5Hz limit. Taking the maximum continuous commutation failure duration of 0.4s as the boundary condition, the inertia demand of the Northwest Power Grid can be estimated according to formula (1).

[0124]

[0125] The average empirical value T of the inertia provided by a single unit capacity of a conventional generator set jBased on an estimated ≈8s, the minimum conventional generating unit capacity required under the constraint of simultaneous transmission and reception DC faults is 240GW. The installed capacity of conventional power sources in the provincial power grid is 50.188 million kilowatts, accounting for 18.6% of the installed capacity of conventional power sources in the regional power grid. According to formulas (2)-(4), the minimum conventional generating unit capacity required by the provincial power grid under the constraint of simultaneous transmission and reception DC faults is 44650MW, of which the minimum capacity required for thermal power is 33980MW.

[0126] The provincial power grid consists of three DC lines: Qishao, Ganzhe, and Longdong. These lines are relatively close in electrical distance, with no more than four substations connecting them, forming a "co-transmission" DC group. The total export capacity of this DC group is 24,000 MW, with 12,000 MW of conventional power generation and 31,300 MW of renewable energy capacity. Qishao and Longdong are conventional DC lines, while Ganzhe is a flexible DC line.

[0127] Considering that an AC fault at the sending end leads to a DC fault at the same sending end, the conventional DC fault time is 5 cycles, or 0.1 seconds. After a flexible DC fault, the deionization time of the DC circuit breaker is considered to be 0.2 seconds. According to formula (6), the inertia of the provincial power grid that satisfies the frequency stability constraint after a DC group fault at the same sending end is calculated as follows:

[0128]

[0129] The average empirical value T of the inertia provided by a single unit capacity of a conventional generator set j Based on an estimated 8 seconds, the minimum operating capacity requirement for conventional generating units constrained by DC faults at the "same-send end" is 20,000 MW.

[0130] Taking into account both the frequency stability constraints after a DC fault at the "same transmission and reception" and "same transmission end" locations, the minimum start-up capacity requirement for thermal power plants is 33,980 MW.

[0131] (2) Minimum operating capacity of thermal power units considering voltage stability constraints

[0132] The provincial power grid has three DC transmission lines: Qishao, Ganzhe, and Longdong, with a total transmission capacity of 24,000 MW. The total installed capacity of conventional power sources is 12,000 MW, and the installed capacity of new energy sources is 31,300 MW.

[0133] The preset threshold for DC multi-infeed short circuit is 3.0. The calculated multi-infeed short circuits of the three DC lines are shown in Table 1.

[0134] Table 1 DC multi-infeed short-circuit ratio

[0135] DC name Short-circuit ratio Qi Shao 6.79 Gansu and Zhejiang 4.87 Longdong 4.30

[0136] As can be seen from Table 1, the short-circuit ratio of all DC multi-infeeds in the power grid of this region is higher than the preset threshold. Therefore, only the 12 thermal power units with DC support are listed as non-shutdown units, while the remaining 377 thermal power units in the system are shut-down units.

[0137] Calculate the voltage change ΔU on the bus connected to the shut-down unit under three types of faults: DC fault, DC group commutation failure fault, or failure of the largest single generator to exit operation. j Based on formula (610), the contribution rate index V of the thermal power unit to the system voltage after the fault is calculated. j The thermal power units are sorted from smallest to largest to form a sequence of units that can be shut down. Due to space limitations, the top 10 thermal power units are shown in Table 2.

[0138] Table 2. Top Ten Thermal Power Units in Ranking by Voltage Contribution Indicators

[0139]

[0140]

[0141] After 268 iterations of calculation, when any one thermal power unit is shut down, the system has a critical value where the DC multi-infeed short-circuit ratio is close to 3. At this point, the total capacity of the remaining 98 thermal power units in the system is taken as the minimum operating capacity of thermal power units that meet the voltage stability constraint. According to formula (11), the minimum operating capacity of thermal power units that meet the voltage stability constraint is calculated to be 31344MW.

[0142] (3) Analysis of the carrying capacity of Gansu power grid considering minimum start-up requirements

[0143] Based on the resource characteristics and grid constraints of each region, the provincial power grid is divided into two regions: "Hexi" and "Central and Eastern". The regions are connected by the Shuiyuan-Baiyin and Wusheng-Hexi double-circuit lines. The limit of the interconnection line based on the safety and stability limit constraints is 12000MW.

[0144] Based on the combined voltage stability and frequency stability constraints, the minimum operating capacity of thermal power units in the provincial power grid is calculated using formula (12) to be 33,980 MW. Then, based on the proportion of conventional units in these two regions, the minimum operating demand in the Hexi region is calculated using formula (13) to be 16,770 MW, and the minimum operating demand in the central and eastern parts of Gansu is 17,210 MW.

[0145] According to the future planning needs of this provincial power grid, the utilization rate of new energy should reach 90%. Considering the minimum starting constraints of thermal power units, the utilization rate of new energy across the provincial power grid under the above boundary conditions is calculated using production simulation to be 86.5%, as shown in Tables 3 and 4. Power curtailment mainly occurs in the "Hexi" region, while the "Central and Eastern" regions have less installed new energy capacity and higher utilization rates. Figure 4 , Figure 5 and Figure 6 As shown.

[0146] Table 3. Provincial power demand considering minimum start-up constraints

[0147] Units: 100 million kilowatt-hours, hours

[0148]

[0149]

[0150] Table 4. Renewable energy consumption in each region considering minimum thermal power plant start-up constraints.

[0151] Units: 100 million kilowatt-hours, hours

[0152]

[0153] To achieve the established goal of 90% renewable energy utilization rate in provincial power grids, two methods can be used: Method 1: Gradually reduce wind and solar installed capacity until the renewable energy utilization rate reaches 90%; Method 2: Increase energy storage capacity until the renewable energy utilization rate reaches 90%.

[0154] Under Method 1, the wind and solar installed capacity schemes are shown in Table 5. When the total installed capacity of new energy decreases by 9796MW and reaches 93.53MW, the utilization rate of new energy can reach the target of 90%.

[0155] Under Method 2, the energy storage capacity configuration scheme is shown in Table 6. The optimal energy storage configuration of 9,000 MW·5 hours can increase the renewable energy consumption rate in Hexi from 81.9% to 87.9%, and the overall grid consumption rate in Gansu to 90%.

[0156] Table 5 Wind and Solar Power Capacity Scheme

[0157]

[0158] Table 6. Renewable Energy Consumption under Different Energy Storage Configurations

[0159]

[0160] Example 3

[0161] Based on the same inventive concept, this invention also provides a system 700 for confirming the renewable energy carrying capacity of a provincial power grid, such as... Figure 7 As shown, it includes:

[0162] The first minimum operating capacity determination module 710 is used to determine the first minimum operating capacity of thermal power units in the provincial power grid considering frequency stability constraints.

[0163] The second minimum operating capacity determination module 720 is used to determine the second minimum operating capacity of thermal power units in the provincial power grid considering voltage stability constraints.

[0164] The zone capacity calculation module 730 is used to divide the provincial power grid into multiple zones based on the tie line; and to calculate the minimum operating capacity of thermal power units in each zone according to the first minimum operating capacity and the second minimum operating capacity.

[0165] The carrying capacity determination module 740 is used to set the renewable energy absorption rate. Based on the renewable energy absorption rate and the minimum operating capacity of thermal power units in each zone, it determines whether the renewable energy absorption rate of each zone has reached the limit. If the limit is reached, the total renewable energy installed capacity of each zone is determined as the renewable energy carrying capacity of the provincial power grid.

[0166] Furthermore, the partition capacity calculation module includes:

[0167] The minimum capacity calculation submodule for each zone is used to calculate the minimum operating capacity P of the thermal power units in each zone. G min The specific formula is as follows:

[0168] P G min =max(P U min ,P GNmin )

[0169] The capacity allocation submodule is used to allocate the minimum operating capacity P of the thermal power unit. G min The specific formula for allocating to each partition is as follows:

[0170]

[0171] P Gk P represents the minimum operating capacity of thermal power plants in the k-th zone; RUN k Let be the standard assembly capacity of the k-th partition.

[0172] Furthermore, the load-bearing capacity determination module also includes:

[0173] If the limit is not reached, the installed capacity of new energy in each zone will be increased;

[0174] If the limit is exceeded, the installed capacity of new energy in each zone will be reduced.

[0175] The present invention provides a method and system for evaluating the capacity of a provincial power grid to support new energy sources. It takes into account voltage stability, frequency stability and balance constraints, and can accurately evaluate the capacity of a provincial power grid to support new energy sources.

[0176] Those skilled in the art will understand that embodiments of the present invention can be provided as methods, systems, or computer program products. Therefore, the present invention can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention can 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.) containing computer-usable program code.

[0177] This invention is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart illustrations and / or block diagrams. Figure 1 a process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0178] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 a process or multiple processes and / or boxes Figure 1 The function specified in one or more boxes.

[0179] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 a process or multiple processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0180] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the scope of the claims of the present invention.

Claims

1. A method for assessing the capacity of a provincial power grid to support new energy sources, characterized in that, include: Determine the first minimum operating capacity of thermal power units in the provincial power grid, taking frequency stability constraints into account; Determine the second minimum operating capacity of thermal power units in the provincial power grid, taking voltage stability constraints into account; Based on the tie line, the provincial power grid is divided into multiple zones; the minimum operating capacity of thermal power units in each zone is calculated according to the first minimum operating capacity and the second minimum operating capacity. A renewable energy absorption rate is set. Based on the renewable energy absorption rate and the minimum operating capacity of thermal power units in each zone, power balance calculation is performed through production simulation to determine whether the renewable energy absorption rate of each zone has reached the limit. If the limit is reached, the sum of the renewable energy installed capacity of each zone is determined as the renewable energy carrying capacity of the provincial power grid. Determine the first minimum operating capacity of thermal power units in the provincial power grid, taking into account frequency stability constraints, including: Collect the installed capacity P of conventional generating units in provincial power grids RUN Including thermal power units P GN Hydropower unit P HN Gas turbine unit P NN Nuclear power unit P NU ; Collect the conventional installed capacity of the regional power grids under the jurisdiction of the provincial power grid. Information such as DC sending and receiving ends and transmission capacity is used to divide DCs in the regional power grid that meet the "same sending and receiving end" requirement into "same sending and receiving" DC groups; The system inertia requirement for a provincial power grid constrained by commutation failure of a DC transmission and reception group is as follows: Among them: W k For the regional power grid inertia requirements, P DCi Let I be the capacity of the i-th simultaneous DC transmission and reception line, I be the total number of simultaneous DC transmission and reception lines, Δf be the system steady-state frequency deviation, and f be the frequency of the line. N The system's rated frequency is given by Δt, which represents the duration of continuous commutation failures in the same DC power supply and receiving circuits. Based on the conventional installed capacity P of the provincial power grid RUN The installed capacity of conventional generating units in the regional power grids under the jurisdiction of provincial power grids Based on the system inertia requirement, the minimum thermal power inertia requirement W of the provincial power grid is calculated according to formula (2). p According to formula (3), the capacity P of the provincial power grid thermal power units that meet the thermal power inertia requirements is calculated. GNj According to formula (4), the first minimum starting capacity P of the thermal power unit that satisfies the frequency stability constraint after the fault of simultaneous power supply and reception is calculated. GNttmin : Among them: W HN W represents the inertia of hydropower units in the provincial power grid. NN For the inertia of the gas turbine unit in the provincial power grid, W SN For the inertia of the provincial power grid solar thermal power unit, T j Let P be the rotor inertia time constant of the j-th generator. GNj Let J be the installed capacity of the j-th generator, and J be the number of thermal power units required to meet the inertia requirement. Collect the sending end point, receiving end point, DC type, DC rated power and grid structure of the provincial power grid DC. If the number of substations connected between two DC converter stations does not exceed 4, the DC will be divided into DC groups with the same sending end or the same receiving end. Calculate the thermal power plant operating capacity P that satisfies the frequency stability constraint after a DC group fault at the same sending or receiving end. GNsmin ; The first minimum operating capacity P of thermal power units in provincial power grids considering frequency stability constraints GNmin for P GNmin =max(P GNttmin ,P GNsmin ) (5); Calculate the thermal power plant operating capacity P that satisfies the frequency stability constraint after a DC group fault at the same sending or receiving end. GNsmin ,include: Calculate the provincial power grid inertia W that satisfies the frequency stability constraint after a DC group fault at the same sending or receiving end. k2 , Where: Δt 常 For the conventional DC blocking duration at the same sending or receiving end, Δt 柔 For the duration of flexible DC blocking at the same sending or receiving end, P DCa P represents the power loss of the conventional DC blocking at the a-th sending or receiving end. DCb Let A be the power loss of the flexible DC blocking at the b-th sending or receiving end, and let B be the total number of conventional DC lines at the sending or receiving end and the total number of flexible DC lines at the sending or receiving end. According to the provincial power grid inertia W k2 Calculate the provincial power grid inertia P that satisfies the frequency stability constraint after a DC group fault at the same sending or receiving end. GNsj , Calculate the first minimum operating capacity P of a thermal power unit that satisfies the frequency stability constraint after a DC group fault at the same sending or receiving end. GNsmin , Based on tie lines, the provincial power grid is divided into multiple zones, including: Based on the maximum power limit of the critical tie line, the provincial power grid is divided into K zones, so that each zone is connected by the critical tie line.

2. The method according to claim 1, characterized in that, The second minimum operating capacity of thermal power units in a provincial power grid, considering voltage stability constraints, is determined, including: Identify the thermal power units that can be shut down among the DC-supported thermal power units in the DC near-area of ​​the provincial power grid; Calculate the voltage change ΔU on the bus connected to the shut-down unit in the event of a DC fault, DC group commutation failure, or the failure of the largest single generator to take off. ij , ΔU ij =|U′ ij -U ij | (9) Among them, U′ ij U represents the voltage value of the busbar connected to the j-th power plant after the i-th fault. ij The voltage value of the busbar connected to the j-th power plant before the i-th fault; The contribution rate index V of thermal power units to system voltage is calculated after a DC fault, a DC group commutation failure, or a single generator of the largest capacity is taken out of service. j , According to V j The value is to sort the thermal power plants from smallest to largest to form a sequence of thermal power units that can be shut down. Based on the shutdown sequence of thermal power units, each unit is shut down sequentially until the maximum voltage change at the node or the DC multi-infeed short-circuit ratio reaches a set threshold. The total capacity of the thermal power units at this point is taken as the second minimum operating capacity P of the thermal power units that meets the voltage stability constraint. Umin , 3. The method according to claim 1, characterized in that, Based on the first minimum operating capacity and the second minimum operating capacity, calculate the minimum operating capacity of thermal power units in each zone, including: Calculate the minimum operating capacity P of thermal power units in each zone. Gmin The specific formula is: P Gmin =max(P Umin ,P GNmin ) (12) The minimum operating capacity P of thermal power units Gmin The specific formula for allocating to each partition is as follows: P Gk P represents the minimum operating capacity of thermal power plants in the k-th zone; RUNk Let be the standard assembly capacity of the k-th partition.

4. The method according to claim 1, characterized in that, After determining whether the renewable energy absorption rate of each zone has reached the limit, the process also includes: If the limit is not reached, the installed capacity of new energy in each zone will be increased; If the limit is exceeded, the installed capacity of new energy in each zone will be reduced.

5. A system for confirming the carrying capacity of new energy sources in a provincial power grid, characterized in that, include: The first minimum operating capacity determination module is used to determine the first minimum operating capacity of thermal power units in the provincial power grid considering frequency stability constraints. The second minimum operating capacity determination module is used to determine the second minimum operating capacity of thermal power units in the provincial power grid considering voltage stability constraints. The zone capacity calculation module is used to divide the provincial power grid into multiple zones based on tie lines; and to calculate the minimum operating capacity of thermal power units in each zone according to the first minimum operating capacity and the second minimum operating capacity. The carrying capacity determination module is used to perform power balance calculations through production simulation based on the set renewable energy absorption rate and the minimum operating capacity of thermal power units in each zone. It determines whether the renewable energy absorption rate of each zone has reached the limit. If the limit has been reached, the total renewable energy installed capacity of each zone is determined as the renewable energy carrying capacity of the provincial power grid. Determine the first minimum operating capacity of thermal power units in the provincial power grid, taking into account frequency stability constraints, including: Collect the installed capacity P of conventional generating units in provincial power grids RUN Including thermal power units P GN Hydropower unit P HN Gas turbine unit P NN Nuclear power unit P NU ; Collect the conventional installed capacity of the regional power grids under the jurisdiction of the provincial power grid. Information such as DC sending and receiving ends and transmission capacity is used to divide DCs in the regional power grid that meet the "same sending and receiving end" requirement into "same sending and receiving" DC groups; The system inertia requirement for a provincial power grid constrained by commutation failure of a DC transmission and reception group is as follows: Among them: W k For the regional power grid inertia requirements, P DCi Let I be the capacity of the i-th simultaneous DC transmission and reception line, I be the total number of simultaneous DC transmission and reception lines, Δf be the system steady-state frequency deviation, and f be the frequency of the line. N The system's rated frequency is given by Δt, which represents the duration of continuous commutation failures in the same DC power supply and receiving circuits. Based on the conventional installed capacity P of the provincial power grid RUN The installed capacity of conventional generating units in the regional power grids under the jurisdiction of provincial power grids Based on the system inertia requirement, the minimum thermal power inertia requirement W of the provincial power grid is calculated according to formula (2). p According to formula (3), the capacity P of the provincial power grid thermal power units that meet the thermal power inertia requirements is calculated. GNj According to formula (4), the first minimum starting capacity P of the thermal power unit that satisfies the frequency stability constraint after the fault of simultaneous power supply and reception is calculated. GNttmin : Among them: W HN W represents the inertia of hydropower units in the provincial power grid. NN For the inertia of the gas turbine unit in the provincial power grid, W SN For the inertia of the provincial power grid solar thermal power unit, T j Let P be the rotor inertia time constant of the j-th generator. GNj Let J be the installed capacity of the j-th generator, and J be the number of thermal power units required to meet the inertia requirement. Collect the sending end point, receiving end point, DC type, DC rated power and grid structure of the provincial power grid DC. If the number of substations connected between two DC converter stations does not exceed 4, the DC will be divided into DC groups with the same sending end or the same receiving end. Calculate the thermal power plant operating capacity P that satisfies the frequency stability constraint after a DC group fault at the same sending or receiving end. GNsmin ; The first minimum operating capacity P of thermal power units in provincial power grids considering frequency stability constraints GNmin for P GNmin =max(P GNttmin ,P GNsmin ) (5); Calculate the thermal power plant operating capacity P that satisfies the frequency stability constraint after a DC group fault at the same sending or receiving end. GNsmin ,include: Calculate the provincial power grid inertia W that satisfies the frequency stability constraint after a DC group fault at the same sending or receiving end. k2 , Where: Δt 常 For the conventional DC blocking duration at the same sending or receiving end, Δt 柔 For the duration of flexible DC blocking at the same sending or receiving end, P DCa P represents the power loss of the conventional DC blocking at the a-th sending or receiving end. DCb Let A be the power loss of the flexible DC blocking at the b-th sending or receiving end, and let B be the total number of conventional DC lines at the sending or receiving end and the total number of flexible DC lines at the sending or receiving end. According to the provincial power grid inertia W k2 Calculate the provincial power grid inertia P that satisfies the frequency stability constraint after a DC group fault at the same sending or receiving end. GNsj , Calculate the first minimum operating capacity P of a thermal power unit that satisfies the frequency stability constraint after a DC group fault at the same sending or receiving end. GNsmin , Based on tie lines, the provincial power grid is divided into multiple zones, including: Based on the maximum power limit of the critical tie line, the provincial power grid is divided into K zones, so that each zone is connected by the critical tie line.

6. The system according to claim 5, characterized in that, The partition capacity calculation module includes: The minimum capacity calculation submodule for each zone is used to calculate the minimum operating capacity P of the thermal power units in each zone. Gmin The specific formula is as follows: P Gmin =max(P Umin ,P GNmin ) The capacity allocation submodule is used to allocate the minimum operating capacity P of the thermal power unit. Gmin The specific formula for allocating to each partition is as follows: P Gk P represents the minimum operating capacity of thermal power plants in the k-th zone; RUNk Let be the standard assembly capacity of the k-th partition.

7. The system according to claim 5, characterized in that, The load-bearing capacity determination module also includes: If the limit is not reached, the installed capacity of new energy in each zone will be increased; If the limit is exceeded, the installed capacity of new energy in each zone will be reduced.

8. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by a processor, it implements the steps of the method according to any one of claims 1 to 4.

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