Investment selection method for power distribution network in energy transformation area

Abstract

The invention discloses an investment selection method for an energy transformation regional power distribution network, and belongs to the technical field of power equipment investment. Comprising the following steps: 1) constructing an index system for evaluating an investment method, the index system comprising an investment benefit index and a characterization index for evaluating distributed new energy; 2) numeralizing the investment benefit index and the characterization index in the step 1); 3) calculating the investment benefit of the power distribution network construction project according to the numerical value in the step 2); and 4) performing reasonable investment arrangement according to the comprehensive benefit value of the power grid construction project obtained in the step 3). According to the investment calculation method provided by the invention, the maximum benefit can be exerted through limited investment, the investment efficiency and the operation efficiency of the power distribution network are improved, and large-scale access of new energy is promoted.

Description

Technical Field

[0001] The present invention belongs to the technical field of power equipment investment, and specifically relates to a distribution network investment and application method under energy transformation. Background Art

[0002] Renewable energy includes solar energy, hydropower, wind energy, biomass energy, wave energy, tidal energy, ocean temperature difference energy, geothermal energy, etc. With the advancement of global energy transformation, the proportion of renewable energy in the energy system is increasing. As an important secondary energy source, electricity plays a key role in energy transformation.

[0003] The distribution network that accepts large-scale renewable energy as its main feature has become the main trend and direction of future distribution network development. The access of new energy has changed the energy flow mode of traditional distribution networks, bringing great challenges to the economy, reliability, and power quality of distribution networks, and thus also affecting the investment in distribution network construction. In the case of limited investment funds, it is very necessary to select appropriate grid construction projects for power supply areas with energy transformation, so as to enable large-scale access of distributed power sources and maximize investment benefits.

[0004] Moreover, most of the existing distribution network investment and application methods fail to fully consider the impact and demand of energy transformation, resulting in problems such as delayed distribution network construction, waste of resources, and low operating efficiency.

[0005] Therefore, it is urgent to design a distribution network investment and application method under energy transformation. Summary of the invention

[0006] In response to the above technical problems, the present invention provides an investment selection method for energy transformation regional distribution networks, which can maximize the benefits of limited investment, improve the investment efficiency and operation efficiency of distribution networks, and promote large-scale access to new energy.

[0007] The technical solution of the present invention is: a method for selecting investment in regional distribution networks for energy transformation, comprising the following steps:

[0008] 1) Constructing an index system for evaluating investment methods, wherein the index system includes investment benefit indexes and characterization indexes for evaluating distributed new energy;

[0009] 2) quantifying the investment benefit index and characterization index in step 1);

[0010] 3) Calculate the investment benefit of the distribution network construction project based on the values ​​in step 2);

[0011] 4) Make reasonable investment arrangements based on the comprehensive benefit value of the power grid construction project obtained in step 3).

[0012] Preferably, before executing step 3), conditions are set to determine whether the target area is applicable to the method.

[0013] Preferably, in step 1), an indicator system including 5 investment benefit indicators and 3 characterization indicators is constructed;

[0014] The five investment benefit indicators are the increase in power supply per unit investment, the reduction in power loss in the distribution network, the comprehensive voltage qualification rate, power supply reliability and carbon emissions;

[0015] The three characterization indicators are distributed power supply reverse transmission, reverse heavy overload and layered open capacity.

[0016] Preferably, in step 2), the power supply increase per unit investment is calculated as follows:

[0017] Increased power supply per unit investment (kWh / yuan) = new power supply in the region / project investment.

[0018] Preferably, in step 2), the calculation formula for the power loss reduction of the distribution network is:

[0019] The amount of electricity loss reduced in the distribution network (kWh) = the electricity loss in the area before the project was implemented - the electricity loss in the area after the project was implemented.

[0020] Preferably, in step 2), the comprehensive voltage qualification rate calculation formula is:

[0021] Comprehensive voltage qualified rate (%) = 0.5* qualified rate of Class A monitoring points + 0.5* (qualified rate of Class B monitoring points + qualified rate of Class C monitoring points + qualified rate of Class D monitoring points) / 3.

[0022] Preferably, in step 2), the power supply reliability rate is divided into a load point index and a system reliability index; a simulation system is established based on the target area, and the load point index and the system reliability index are calculated;

[0023] The load point indicators include failure rate λ, annual average power outage time U and average power outage duration r;

[0024] Where: λ=∑λ ij / NS

[0025] Where i is the number of component failures in each simulation, j is the number of simulations, and NS is the total simulation time;

[0026] U=∑t ij / NS

[0027] Where t ij is the power outage time of each load point in each simulation;

[0028] r=U / λ

[0029] System indicators include the system average power outage frequency index SAIFI, the system average power outage duration index SAIDI and the average power supply availability index ASAI;

[0030] Where SAIFI = ∑ i λ i N i / ∑ i N i

[0031] The average power outage frequency index of the system indicates the number of power outages for users in the system within a certain period of time, where N i is the number of users;

[0032] SAIDI=∑ i U i N i / ∑ i N i

[0033] The average power outage duration indicator of the system indicates the time required to restore power supply after each system failure;

[0034] ASAI=∑ i N i ×8760-∑ i U i N i / ∑ i N i ×8760

[0035] The average power supply availability index indicates the proportion of time that the system power supply meets user demand to the total time within a certain period of time.

[0036] Preferably, in step 2), the carbon emissions calculation formula is:

[0037] E 电力 =(AD 园区电力 -AD 可再生电力 )×EF 电

[0038] Where:

[0039] E 电力 is the emission corresponding to electricity consumption, in tons of carbon dioxide (tCO2);

[0040] AD 园区电力 The unit of electricity consumption is megawatt-hour (MWh);

[0041] AD 可再生电力 The amount of renewable energy power generation consumed is expressed in megawatt-hours (MWh);

[0042] EF 电 is the grid emission factor, expressed in tons of carbon dioxide per megawatt-hour (tCO2 / MWh).

[0043] Preferably, in step 2), the distributed power supply reverse transmission calculation formula is:

[0044] Distributed power supply reverse transmission (%) = the number of devices with distributed power supply reverse transmission in the area / the total number of devices in the area * 100%.

[0045] Preferably, in step 2), the reverse heavy overload calculation formula is:

[0046] Reverse heavy overload (%) = number of devices with reverse heavy overload in the area / total number of devices in the area * 100%.

[0047] Preferably, in step 2), the open capacity of the distribution network, i.e., the open capacity of the 110 (35) kV substation in the region, is calculated as follows:

[0048] The open capacity of the 110(35) kV main transformer includes three values: main transformer carrying capacity, short-circuit current and voltage deviation.

[0049] The main transformer carrying capacity is considered to be not overloaded when the photovoltaic load is reversed. The calculation formula is: main transformer carrying capacity = main transformer load at typical time + main transformer capacity × 0.8, and the 110 (35) kV main transformer reverses without overloading and allows photovoltaic output;

[0050] The short-circuit current evaluates the upper limit of distributed photovoltaic output allowed by the high and low voltage side busbars. The calculation formula is:

[0051]

[0052] Where P m I is the upper limit of the distributed photovoltaic output on the bus side; xz U is the current value of the busbar short-circuit current under the maximum operation mode of the system, which can be determined according to the busbar maximum mode short-circuit capacity; N is the rated voltage of each busbar; the short-circuit current generated by distributed photovoltaics usually does not exceed 1.5 times its rated current; I m For the allowable short-circuit current limit, select the minimum value of the breaking current limit of the corresponding circuit breaker connected to the busbar.

[0053] The voltage deviation evaluates the active power reversed by the distributed photovoltaic output of the high and low voltage side busbars, and the calculation formula is:

[0054]

[0055] Where P is the distributed photovoltaic output return active value; ΔQ is the photovoltaic system reactive power increment, is the distributed photovoltaic power factor. Where ΔQ=S sc *δU / 100, U sj is the actual value of bus voltage, δU is the upper limit of bus voltage margin, and the calculation formula is:

[0056] S sc is the busbar small mode short-circuit capacity, and the calculation formula is:

[0057]

[0058] The obtained distributed photovoltaic output returned active power value is superimposed with the load carried by the high and low voltage side bus (high and low voltage side bus load on the minimum load day), and the active power value allowed by the high and low voltage side bus to access the distributed photovoltaic power is calculated.

[0059] The three calculation results of the upper limit of distributed photovoltaic output obtained in the above steps are compared, and the minimum value is selected as the maximum photovoltaic output allowed by the main transformer. The open capacity of all main transformers in the area is summarized to obtain the open capacity index value of the distribution network.

[0060] Preferably, step 3) analyzes and locates the target area to determine whether the target area is applicable to the method; the specific steps are:

[0061] 3.1 Predict the installed capacity of distributed power generation in the target area;

[0062] 3.2 Calculate the available capacity of the target area;

[0063] 3.3 If 3.1 is greater than 3.2, this method needs to be applied.

[0064] Preferably, the calculation of the investment benefit of the distribution network construction project in step 4) includes:

[0065] 4.1 Indicator Quantification

[0066] 4.1.1 Select distribution network construction projects in the target area;

[0067] 4.1.2 Based on step 2), calculate the eight index values ​​of each power grid project;

[0068] The following is the entropy method process:

[0069] 4.1.3 Use the normalization method to standardize the index values;

[0070] 4.1.4 Calculate the weight of each indicator for different projects;

[0071] 4.1.5 Calculate the entropy value of each indicator for different projects;

[0072] 4.1.6 Calculate the contribution of different projects according to the two cases of equal and unequal weights to obtain the comprehensive benefit value of each power grid construction project.

[0073] Preferably, the calculation method of the normalization method is: within the range of a single indicator corresponding to the construction project, the difference between the value and the minimum value is divided by the difference between the maximum value and the minimum value;

[0074] If the value is the minimum, the result of the entire expression is 0, and the formula is adjusted by adding 0.01 to avoid the ratio being 0;

[0075] If the value is not the minimum, the ratio is calculated directly.

[0076] Preferably, the weight is calculated by dividing the value normalized by the sum of all values ​​under the indicator normalized by the normalization method.

[0077] Preferably, the entropy value of each indicator of different projects is calculated as follows:

[0078] 4.1.5.1: Multiply the weight value by its natural logarithm;

[0079] 4.1.5.2: Sum all the values ​​obtained in the previous step;

[0080] 4.1.5.3: Divide -1 by LN(M) and multiply the value obtained in the previous step to get the entropy value, where M is the number of items involved in the evaluation;

[0081] 4.1.5.4: Subtract the entropy value obtained in the previous step from 1 to get the coefficient of variation;

[0082] 4.1.5.5: Divide the difference coefficient by the sum of the difference coefficients of the increase in power supply per unit investment, the reduction in power loss in the distribution network, the comprehensive voltage qualification rate, power supply reliability, carbon emissions, the open capacity of the distribution network, the reverse transmission of distributed power sources, and reverse heavy overload to obtain the weight value of the first item;

[0083] 4.1.5.6: The weight coefficients of power supply increase per unit investment, power loss reduction of distribution network, comprehensive voltage qualification rate, power supply reliability, carbon emissions, open capacity of distribution network, reverse transmission of distributed power source, and reverse heavy overload are 0.1, 0.1, 0.1, 0.1, 0.1, 0.1, 0.2, 0.2 respectively;

[0084] 4.1.5.7: Multiply the weight value of the first item by the proportion coefficient, and divide it by the sum of the weight value of the first item corresponding to the unit investment increase in power supply, power loss reduction in distribution network, comprehensive voltage qualification rate, power supply reliability, carbon emissions, open capacity of distribution network, reverse transmission of distributed power sources, and reverse overload multiplied by the proportion coefficient to obtain the weight value of the second item;

[0085] Preferably, the calculation method according to equal weights is: multiplying the standard value by the weight value of the first item;

[0086] The calculation method for unequal weights is: multiply the standard value by the weight value of the second item.

[0087] Preferably, the step 5) comprises:

[0088] 5.1 Rank the comprehensive benefits of power grid construction projects in order.

[0089] 5.2 When the investment amount is fixed, the selection of construction projects should be reasonably arranged according to the order of benefit value.

[0090] The beneficial effects of the present invention are:

[0091] An evaluation index system consisting of 5 investment benefit indicators and 3 characterization indicators is constructed to fully consider the impact and demand of energy transformation. The indicator values ​​are then entropy-calculated and assigned appropriate weights to obtain the final contribution value of each project, thereby maximizing the investment benefit.

[0092] According to the investment calculation method provided by the present invention, limited investment can be used to maximize benefits, improve the investment efficiency and operation efficiency of the distribution network, and promote large-scale access to new energy. BRIEF DESCRIPTION OF THE DRAWINGS

[0093] Figure 1 is a schematic flow chart of the method of the present invention,

[0094] Figure 2 This is a schematic diagram of indicator selection and extraction.

[0095] Figure 3 The embodiment is a table of investment benefit indicators and characterization indicators in numerical form.

[0096] Figure 4 It is a table that has been standardized using the normalization method.

[0097] Figure 5 Table for calculating indicator weights,

[0098] Figure 6 It is a table obtained by calculating the entropy value of the indicator.

[0099] Figure 7 This is a table obtained by calculating the project contribution with equal weight values.

[0100] Figure 8 This is a table obtained by calculating the contribution of projects with unequal weight values. DETAILED DESCRIPTION

[0101] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0102] The present invention provides an investment selection method for energy transformation regional distribution network, see Figure 1 , including the following steps,

[0103] 1) Construct an indicator system for evaluating investment methods, which includes investment benefit indicators and characterization indicators for evaluating distributed new energy;

[0104] 2) quantifying the investment benefit index and characterization index in step 1);

[0105] 3) Calculate the investment benefit of the distribution network construction project based on the values ​​in step 2);

[0106] 4) Make reasonable investment arrangements based on the comprehensive benefit value of the power grid construction project obtained in step 3).

[0107] In this embodiment, before executing step 3), a condition is also set to determine whether the target area is applicable to the method.

[0108] The specific steps are:

[0109] 3.1 Predict the installed capacity of distributed power generation in the target area; the calculation process is conventional technology and will not be repeated here.

[0110] 3.2 Calculate the open capacity of the target area; the calculation process is conventional technology and will not be repeated here.

[0111] 3.3 If 3.1 is greater than 3.2, this method needs to be applied. By comparison, the area where this method needs to be applied is found, that is, the acceptance capacity of distributed power sources in the area is judged.

[0112] Construct an indicator system including 5 investment benefit indicators and 3 characterization indicators;

[0113] The five investment benefit indicators are the increase in power supply per unit investment, the reduction in power loss in the distribution network, the comprehensive voltage qualification rate, power supply reliability and carbon emissions;

[0114] The three characterization indicators are distributed power supply reverse transmission, reverse heavy overload and layered open capacity.

[0115] In order to analyze the relationship between investment decisions and energy transformation, this embodiment proposes an analysis method through the relationship chain of "investment direction-specific measures-distribution network affected parameters-grid construction-investment benefits", see Figure 2 The index characterizing "distribution network affected parameters - power grid construction" is extracted. The investment direction of distribution network planning, specific construction and transformation measures, distribution network parameters and power grid operation indicators affected by the measures, and investment benefit indicators are introduced to link investment decisions with energy transformation.

[0116] In step 2), the power supply per unit investment is the power supply per unit investment in the regional distribution network after the project is implemented. The calculation formula is:

[0117] Increased power supply per unit investment (kWh / yuan) = new power supply in the region / project investment.

[0118] The power loss reduction of the distribution network refers to the power loss reduction of the distribution network in the region after the project is implemented. The calculation formula is:

[0119] The amount of electricity loss reduced in the distribution network (kWh) = the electricity loss in the area before the project was implemented - the electricity loss in the area after the project was implemented.

[0120] The comprehensive voltage qualification rate is the ratio of the cumulative operating time of the medium voltage distribution network operating voltage within the allowable voltage deviation range to the corresponding total operating statistical time. The calculation formula is:

[0121] Comprehensive voltage qualified rate (%) = 0.5* qualified rate of class A monitoring points + 0.5* (qualified rate of class B monitoring points + qualified rate of class C monitoring points + qualified rate of class D monitoring points) / 3. How to obtain relevant data is a conventional technology and will not be described in detail.

[0122] The power supply reliability rate is divided into load point index and system reliability index, which reflects the ability of the medium voltage distribution network to continuously supply power to users; a simulation system is established based on the target area. How to establish a simulation system and extract data is a conventional technology and will not be described in detail, and the load point index and system reliability index are calculated;

[0123] The load point index reflects the operating status between the load point and each component, and is a probabilistic index under state assessment.

[0124] The load point indicators include failure rate λ, annual average power outage time U and average power outage duration r;

[0125] Where: λ=∑λ ij / NS

[0126] The failure rate is the number of power outages that occur at a load point within a certain period of time. The greater the failure rate, the more component failures there are and the less reliable the system is. Where i is the number of component failures in each simulation, j is the number of simulations, and NS is the total simulation time;

[0127] U=∑t ij / NS

[0128] The annual average power outage time is the average power outage time of the load point each year during the simulation process. The longer the annual average power outage time is, the less reliable the system is. ij is the power outage time of each load point in each simulation;

[0129] r=U / λ

[0130] The average power outage duration is the average duration of each power outage among all power outages at the load point. It represents the system's repair capability. The larger the value, the worse the system's repair capability.

[0131] System indicators are the reliability representation of the overall operation of the system. When a system or component fails, the impact on the normal operation of the system is evaluated based on the calculation of load point indicators. They include the system average power outage frequency index SAIFI, the system average power outage duration index SAIDI and the average power supply availability index ASAI;

[0132] Where SAIFI = ∑ i λ i N i / ∑ i N i

[0133] The average power outage frequency index of the system indicates the number of power outages for users in the system within a certain period of time, where N i is the number of users;

[0134] SAIDI=∑ i U i N i / ∑ i N i

[0135] The system average power outage duration indicator indicates the time required to restore power after each system failure; the longer the recovery time, the greater the loss to users.

[0136] ASAI=∑ i N i ×8760-∑ i U i N i / ∑ i N i ×8760

[0137] The average power supply availability index indicates the proportion of the time that the system power supply meets the user demand to the total time within a certain period of time. The time of the present invention is 365 times 24 hours, that is, one natural year.

[0138] Carbon emissions reflect the overall situation of carbon emissions in the region. In this invention, it mainly refers to the carbon dioxide emissions generated by the use of electricity. The calculation formula is:

[0139] E 电力 =(AD 园区电力 -AD 可再生电力 )×EF 电

[0140] Where:

[0141] E 电力 is the emission corresponding to electricity consumption, in tons of carbon dioxide (tCO2);

[0142] AD 园区电力 The unit of electricity consumption is megawatt-hour (MWh);

[0143] AD 可再生电力 The amount of renewable energy power generation consumed is expressed in megawatt-hours (MWh);

[0144] EF 电 is the grid emission factor, expressed in tons of carbon dioxide per megawatt-hour (tCO2 / MWh).

[0145] Distributed power supply reverse transmission refers to the proportion of distributed power supply reverse transmission equipment in the region after the project is implemented. The calculation formula is:

[0146] Distributed power supply reverse transmission (%) = the number of devices with distributed power supply reverse transmission in the area / the total number of devices in the area * 100%

[0147] Reverse heavy overload refers to the proportion of reverse heavy overload equipment in the area after the project is implemented. The calculation formula is:

[0148] Reverse heavy overload (%) = Number of devices with reverse heavy overload in the area / Total number of devices in the area * 100%

[0149] How to obtain the above-mentioned relevant data is a conventional technique and will not be described in detail.

[0150] The evaluation of the open capacity of 110(35) kV main transformer mainly considers three factors: equipment carrying capacity, short-circuit current, and voltage deviation. Among them, the equipment carrying capacity evaluates the transformer carrying capacity; the short-circuit current evaluates the short-circuit current margin of the low-voltage side bus and the high-voltage side bus when the short-circuit current does not exceed the limit, thereby calculating the distributed photovoltaic output; the voltage deviation evaluates the voltage deviation margin of the low-voltage side bus and the high-voltage side bus when the voltage deviation does not exceed the limit, thereby calculating the distributed photovoltaic output. The open capacity of the distribution network is the open capacity of the 110(35) kV substation in the region, and the calculation method is as follows:

[0151] The main transformer carrying capacity takes into account that when the photovoltaic load is reversed, the main transformer is not overloaded. The calculation formula is: main transformer carrying capacity = main transformer load at typical time + main transformer capacity × 0.8, and the 110 (35) kV main transformer is reversed without overload and allows photovoltaic output;

[0152] The short-circuit current evaluates the upper limit of distributed photovoltaic output allowed by the high- and low-voltage side busbars. The calculation formula is:

[0153]

[0154] Where P m I is the upper limit of the distributed photovoltaic output on the bus side; xz U is the current value of the busbar short-circuit current under the maximum operation mode of the system, which can be determined according to the busbar maximum mode short-circuit capacity; N is the rated voltage of each busbar; the short-circuit current generated by distributed photovoltaics usually does not exceed 1.5 times its rated current; I m For the allowable short-circuit current limit, select the minimum value of the breaking current limit of the corresponding circuit breaker connected to the busbar.

[0155] Voltage deviation evaluates the active power reversed by distributed photovoltaic output on the high and low voltage side busbars. The calculation formula is:

[0156]

[0157] Where P is the distributed photovoltaic output return active value; ΔQ is the photovoltaic system reactive power increment, is the distributed photovoltaic power factor. Where ΔQ=S sc *δU / 100, δU is the upper limit of bus voltage margin, and the calculation formula is:

[0158] U sj is the actual value of bus voltage, S sc is the busbar small mode short-circuit capacity, and the calculation formula is:

[0159]

[0160] Where S jz is the base capacity, X * It is the per unit value of the short-circuit reactance on the bus side of the small mode. How to obtain the relevant data is a conventional technology and will not be described in detail.

[0161] The obtained distributed photovoltaic output returned active power value is superimposed with the load carried by the high and low voltage side bus (high and low voltage side bus load on the minimum load day), and the active power value allowed by the high and low voltage side bus to access the distributed photovoltaic power is calculated.

[0162] The three calculation results of the upper limit of distributed photovoltaic output obtained in the above steps are compared, and the minimum value is selected as the maximum photovoltaic output allowed by the main transformer. The open capacity of all main transformers in the area is summarized to obtain the open capacity index value of the distribution network.

[0163] Step 4) Calculation of investment benefits of distribution network construction projects, including

[0164] 4.1 Indicator Quantification

[0165] 4.1.1 Selection of distribution network construction projects in the target area

[0166] 4.1.2 Based on step 2), calculate the eight index values ​​of each power grid project

[0167] The following is the entropy method process:

[0168] 4.1.3 Use the normalization method to standardize the index values;

[0169] 4.1.4 The decision weights for different schemes based on the same indicator are different. Calculate the weight ratio of each type of indicator for different projects;

[0170] 4.1.5 Calculate the entropy value of each indicator for different projects;

[0171] 4.1.6 Calculate the contribution of different projects based on the two cases of equal and unequal weights to obtain the comprehensive benefit value of each power grid construction project.

[0172] The calculation method of the normalization method is: within the range of a single indicator corresponding to the construction project, the difference between the value and the minimum value is divided by the difference between the maximum value and the minimum value;

[0173] If the value is the minimum, the result of the entire expression is 0, and the formula is adjusted by adding 0.01 to avoid the ratio being 0;

[0174] If the value is not the minimum, the ratio is calculated directly.

[0175] The weight is calculated by dividing the normalized value by the sum of all normalized values ​​under the indicator.

[0176] Calculate the entropy value of each indicator of different projects. The calculation method is:

[0177] 4.1.5.1: Multiply the weight value by its natural logarithm;

[0178] 4.1.5.2: Sum all the values ​​obtained in the previous step;

[0179] 4.1.5.3: Divide -1 by LN(M) and multiply the value obtained in the previous step to get the entropy value, where M is the number of items involved in the evaluation;

[0180] 4.1.5.4: Subtract the entropy value obtained in the previous step from 1 to get the coefficient of variation;

[0181] 4.1.5.5: Divide the difference coefficient by the sum of the difference coefficients of increased power supply per unit investment, reduced power loss in the distribution network, comprehensive voltage compliance rate, power supply reliability, carbon emissions, open capacity of the distribution network, reverse transmission of distributed power sources, and reverse heavy overload to obtain the weight value of the first item; the sum of all the weight values ​​of the first items should be equal to 1.

[0182] 4.1.5.6: Assume that the weight coefficients of power supply increase per unit investment, power loss reduction in distribution network, comprehensive voltage qualification rate, power supply reliability, carbon emissions, open capacity of distribution network, reverse transmission of distributed power sources, and reverse heavy overload are 0.1, 0.1, 0.1, 0.1, 0.1, 0.1, 0.2, and 0.2 respectively; it should be noted that those skilled in the art can define other weight coefficients according to actual needs, and the changes made thereto are also within the scope of protection of the present invention.

[0183] 4.1.5.7: Multiply the weight value of the first project by the weight coefficient, and divide it by the sum of the weight values ​​of the first project corresponding to the unit investment increase in power supply, distribution network loss reduction, comprehensive voltage qualification rate, power supply reliability, carbon emissions, distribution network open capacity, distributed power supply reverse transmission, and reverse overload multiplied by the weight value of the second project by the weight coefficient to obtain the weight value of the second project. The sum of all the weight values ​​of the first project should be equal to 1

[0184] The calculation method for equal weights is: multiply the standard value by the weight value of the first item;

[0185] The calculation method for unequal weights is: multiply the standard value by the weight value of the second item.

[0186] Step 5) includes:

[0187] 5.1 Rank the comprehensive benefits of power grid construction projects in order.

[0188] 5.2 When the investment amount is fixed, the selection of construction projects should be reasonably arranged according to the order of benefit value.

[0189] Specifically:

[0190] The grid structure and equipment level of the first category area are relatively good (for example, the new district distribution network has a relatively good foundation), which can meet the demand for load growth and the absorption of distributed power sources in the whole county without increasing the investment in distributed power sources and primary facilities. The region has a high economic level and higher requirements for reliability and power supply quality. The reliability and power supply quality can be improved through investment in secondary facilities.

[0191] The second type of regional distribution network has a weak grid structure (such as newly planned and undeveloped regional distribution networks), which makes it difficult to meet the needs of load growth and distributed power access, and requires increased investment in primary facilities and distributed power. The region has a low economic level and low requirements for reliability and power supply quality. The existing secondary facilities can meet the requirements, so there is no need to increase secondary facility investment.

[0192] The existing facilities of Category 3 can meet the requirements for distributed power access (such as county distribution networks) without increasing distributed power investment. The load growth rate and economic level in this area are relatively high, and the power supply capacity, power quality and reliability are required to be high. Both primary and secondary facilities need to be invested to meet the balanced development of this type of power grid.

[0193] In the fourth category, the distribution network is developing slowly (such as rural distribution network areas), and investment in primary and secondary facilities is required to promote balanced development of power supply capacity, power quality and reliability.

[0194] The following takes 10 distribution network construction projects as an example to describe the calculation process in detail.

[0195] See also Figure 3 , 10 distribution network construction projects were selected, and the corresponding 5 investment benefit indicators and 3 characterization index values ​​were calculated.

[0196] See also Figure 4 ,Data standardization processing uses the normalization method to standardize the data.

[0197] See also Figure 5 ,Indicator weight calculation combines the standardized data to calculate the indicator weight of each project.

[0198] See also Figure 6 , Indicator entropy value calculation Calculate the indicator entropy value and determine the weight of each item.

[0199] See also Figure 7 The weights are equal and Figure 8 The weight values ​​are not equal, the index entropy value is calculated, and the contribution of each project is calculated according to the project weight, and the beneficial effects of the present invention are:

[0200] The present invention constructs an evaluation index system including 5 investment benefit indicators and 3 characterization indicators, so as to fully consider the impact and demand of energy transformation, and then perform entropy calculation on the indicator values, assign appropriate weights, and obtain the final contribution value of each project, so as to maximize the investment benefit, quantify the investment benefit, and facilitate decision-making.

[0201] According to the investment calculation method provided by the present invention, limited investment can be used to maximize benefits, improve the investment efficiency and operation efficiency of the distribution network, and promote large-scale access to new energy.

[0202] The present invention is not limited to the above-mentioned embodiments. On the basis of the technical solution disclosed in the present invention, technicians in this field can make some substitutions and deformations to some technical features therein according to the disclosed technical content without creative labor, and these substitutions and deformations are all within the protection scope of the present invention.

Claims

1. An investment selection method for regional distribution networks in energy transition, Its characteristics are: The following steps are included: 1) Constructing an index system for evaluating investment methods, wherein the index system includes investment benefit indexes and characterization indexes for evaluating distributed new energy; 2) quantifying the investment benefit index and characterization index in step 1); 3) Calculate the investment benefit of the distribution network construction project based on the values ​​in step 2); 4) Make reasonable investment arrangements based on the comprehensive benefit value of the power grid construction project obtained in step 3).

2. A method for selecting investment in a regional distribution network for energy transition according to claim 1, Its characteristics are: Before executing step 3), conditions must be set to determine whether the target area is suitable for this method.

3. A method for selecting investment in a regional distribution network for energy transition according to claim 1, Its characteristics are: In the step 1), an indicator system including 5 investment benefit indicators and 3 characterization indicators is constructed; The five investment benefit indicators are the increase in power supply per unit investment, the reduction in power loss in the distribution network, the comprehensive voltage qualification rate, power supply reliability and carbon emissions; The three characterization indicators are distributed power supply reverse transmission, reverse heavy overload and layered open capacity.

4. A method for selecting investment in a regional distribution network for energy transformation according to claim 3, Its characteristics are: In step 2), the power supply increase per unit investment is calculated as follows: Increased power supply per unit investment (kWh / yuan) = new power supply in the region / project investment.

5. A method for selecting investment in regional distribution networks for energy transformation according to claim 3, Its characteristics are: In step 2), the calculation formula for the power loss reduction of the distribution network is: The amount of electricity loss reduced in the distribution network (kWh) = the electricity loss in the area before the project was implemented - the electricity loss in the area after the project was implemented.

6. A method for selecting investment in regional distribution networks for energy transformation according to claim 3, Its characteristics are: In the step 2), the comprehensive voltage qualification rate calculation formula is: Comprehensive voltage qualified rate (%) = 0.5* qualified rate of Class A monitoring points + 0.5* (qualified rate of Class B monitoring points + qualified rate of Class C monitoring points + qualified rate of Class D monitoring points) / 3.

7. A method for selecting investment in regional distribution networks for energy transformation according to claim 3, Its characteristics are: In the step 2), the power supply reliability rate is divided into a load point index and a system reliability index; a simulation system is established based on the target area, and the load point index and the system reliability index are calculated; The load point indicators include failure rate λ, annual average power outage time U and average power outage duration r; Where: λ=∑λ ij / NS Where i is the number of component failures in each simulation, j is the number of simulations, and NS is the total simulation time; U=∑t ij / NS Where t ij is the power outage time of each load point in each simulation; r=U / λ System indicators include the system average power outage frequency index SAIFI, the system average power outage duration index SAIDI and the average power supply availability index ASAI; Where SAIFI = ∑ i λ i N i / ∑ i N i The average power outage frequency index of the system indicates the number of power outages for users in the system within a certain period of time, where N i is the number of users; <h2 style=";text-align:left;direction:ltr">SAIDI=∑<h2 style=";text-align:left;direction:ltr"> i <h2 style=";text-align:left;direction:ltr"> U<h2 style=";text-align:left;direction:ltr"> i <h2 style=";text-align:left;direction:ltr"> N<h2 style=";text-align:left;direction:ltr"> i <h2 style=";text-align:left;direction:ltr"> / ∑<h2 style=";text-align:left;direction:ltr"> i <h2 style=";text-align:left;direction:ltr"> N<h2 style=";text-align:left;direction:ltr"> i The average power outage duration indicator of the system indicates the time required to restore power supply after each system failure; ASAI=∑ i N i ×8760-∑ i U i N i / ∑ i N i ×8760 The average power supply availability index indicates the proportion of time that the system power supply meets user demand to the total time within a certain period of time.

8. A method for selecting investment in regional distribution networks for energy transformation according to claim 3, Its characteristics are: In the step 2), the carbon emission calculation formula is: AND 电力 =(AD 园区电力 -TO 可再生电力 )×EF 电 Where: E 电力 is the emission corresponding to electricity consumption, in tons of carbon dioxide (tCO2); AD 园区电力 The unit of electricity consumption is megawatt-hour (MWh); AD 可再生电力 The amount of renewable energy power generation consumed, in megawatt-hours (MWh); EF 电 is the grid emission factor, expressed in tons of carbon dioxide per megawatt-hour (tCO2 / MWh).

9. A method for selecting investment in regional distribution networks for energy transformation according to claim 3, Its characteristics are: In step 2), the distributed power supply reverse transmission calculation formula is: Distributed power supply reverse transmission (%) = the number of devices with distributed power supply reverse transmission in the area / the total number of devices in the area * 100%.

10. A method for selecting investment in regional distribution networks for energy transformation according to claim 3, Its characteristics are: In step 2), the reverse heavy overload calculation formula is: Reverse heavy overload (%) = number of devices with reverse heavy overload in the area / total number of devices in the area * 100%.

11. A method for selecting investment in regional distribution networks for energy transformation according to claim 3, Its characteristics are: In step 2), the open capacity of the distribution network, i.e., the open capacity of the substation in the region, is calculated as follows: The open capacity includes three values: main transformer carrying capacity, short-circuit current and voltage deviation. The main transformer carrying capacity is considered to be not overloaded when the photovoltaic load is reversed. The calculation formula is: main transformer carrying capacity = main transformer load at typical time + main transformer capacity × 0.8, and the photovoltaic output allowed by the main transformer without reverse overload is obtained; The short-circuit current evaluates the upper limit of distributed photovoltaic output allowed by the high and low voltage side busbars. The calculation formula is: Where P m The upper limit of the distributed photovoltaic output on the bus side; I xz U is the current value of the busbar short-circuit current under the maximum operation mode of the system, which can be determined according to the busbar maximum mode short-circuit capacity; N is the rated voltage of each busbar; the short-circuit current generated by distributed photovoltaics usually does not exceed 1.5 times its rated current; I m For the permissible short-circuit current limit, select the minimum value of the breaking current limit of the corresponding circuit breaker connected to the busbar; The voltage deviation evaluates the active power reversed by the distributed photovoltaic output of the high and low voltage side busbars, and the calculation formula is: Where P is the distributed photovoltaic output return active value; ΔQ is the photovoltaic system reactive power increment, is the distributed photovoltaic power factor, where ΔQ = S sc *δU / 100, δU is the upper limit of bus voltage margin, and the calculation formula is: U sj is the actual value of bus voltage, S sc is the busbar small mode short-circuit capacity, and the calculation formula is: Where S jz is the base capacity, X * It is the per unit value of short-circuit reactance on the bus side of small mode. The obtained distributed photovoltaic output return active value is superimposed on the load carried by the high and low voltage side busbars to calculate the active value allowed by the high and low voltage side busbars for distributed photovoltaic access; The three calculation results of the upper limit of distributed photovoltaic output obtained in the above steps are compared, and the minimum value is selected as the maximum photovoltaic output allowed by the main transformer. The open capacity of all main transformers in the area is summarized to obtain the open capacity index value of the distribution network.

12. A method for selecting investment in regional distribution networks for energy transformation according to claim 2, Its characteristics are: Step 3) Analyze and locate the target area to determine whether the target area is suitable for this method; the specific steps are: 3.1 Predict the installed capacity of distributed power generation in the target area; 3.2 Calculate the available capacity of the target area; 3.3 If 3.1 is greater than 3.2, this method needs to be applied.

13. A method for selecting investment in regional distribution networks for energy transformation according to claim 3, Its characteristics are: The calculation of the investment benefit of the distribution network construction project in step 4) includes: 4.1 Quantification of indicators; 4.1.1 Select distribution network construction projects in the target area; 4.1.2 Based on step 2), calculate the eight index values ​​of each power grid project; The following is the entropy method process: 4.1.3 Use the normalization method to standardize the index values; 4.1.4 Calculate the weight of each indicator for different projects; 4.1.5 Calculate the entropy value of each indicator for different projects; 4.1.6 Calculate the contribution of different projects according to the two cases of equal and unequal weights to obtain the comprehensive benefit value of each power grid construction project.

14. A method for selecting investment in regional distribution networks for energy transformation according to claim 13, Its characteristics are: The calculation method of the normalization method is: within the range of a single indicator corresponding to the construction project, the difference between the value and the minimum value is divided by the difference between the maximum value and the minimum value; If the value is the minimum, the result of the entire expression is 0, and the formula is adjusted by adding 0.01 to avoid the ratio being 0; If the value is not the minimum, the ratio is calculated directly.

15. A method for selecting investment in regional distribution networks for energy transformation according to claim 14, Its characteristics are: The weight is calculated by dividing the normalized value by the sum of all normalized values ​​under the indicator.

16. A method for selecting investment in regional distribution networks for energy transformation according to claim 15, Its characteristics are: Calculate the entropy value of each indicator of different projects. The calculation method is: 4.1.5.1: Multiply the weight value by its natural logarithm; 4.1.5.2: Sum all the values ​​obtained in the previous step; 4.1.5.3: Divide -1 by LN(M) and multiply the value obtained in the previous step to get the entropy value, where M is the number of items involved in the evaluation; 4.1.5.4: Subtract the entropy value obtained in the previous step from 1 to get the coefficient of variation; 4.1.5.5: Divide the difference coefficient by the sum of the difference coefficients of the increase in power supply per unit investment, the reduction in power loss in the distribution network, the comprehensive voltage qualification rate, power supply reliability, carbon emissions, the open capacity of the distribution network, the reverse transmission of distributed power sources, and reverse heavy overload to obtain the weight value of the first item; 4.1.5.6: The weight coefficients of power supply increase per unit investment, power loss reduction of distribution network, comprehensive voltage qualification rate, power supply reliability, carbon emissions, open capacity of distribution network, reverse transmission of distributed power source, and reverse heavy overload are 0.1, 0.1, 0.1, 0.1, 0.1, 0.1, 0.2, 0.2 respectively; 4.1.5.7: Multiply the weight value of the first item by the proportion coefficient, and divide it by the sum of the weight value of the first item corresponding to the unit investment increase in power supply, distribution network loss reduction, comprehensive voltage qualification rate, power supply reliability, carbon emissions, distribution network open capacity, distributed power supply reverse transmission, and reverse heavy overload multiplied by the proportion coefficient to obtain the weight value of the second item.

17. A method for selecting investment in regional distribution networks for energy transformation according to claim 16, Its characteristics are: The calculation method for equal weights is: multiply the standard value by the weight value of the first item; The calculation method for unequal weights is: multiply the standard value by the weight value of the second item.

18. The method for selecting investment in regional distribution networks for energy transformation according to claim 13, Its characteristics are: Step 5) include: 5.1 Rank the comprehensive benefits of power grid construction projects in order. 5.2 When the investment amount is fixed, the selection of construction projects should be reasonably arranged according to the order of benefit value.

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