A method for tight power balance in distribution network based on distributed generation output timing

Abstract

The invention discloses a power tight balancing method for a distribution network based on the output timing of distributed power sources: extracting the daily 24-hour active load value of a transformer in historical years, clustering to form a typical daily load curve in four seasons according to the transformer power supply load category, and calculating the normalized value of the 24-hour load in four seasons; predicting the typical daily load value in four seasons of various types of plot properties, calculating the corresponding 24-hour load value, and superimposing the 24-hour load value in four seasons of the regional typical day; extracting the daily 24-hour output value of distributed power sources in historical years, setting the initial value of the confidence probability of the output of distributed power sources, clustering to form a typical confidence output curve in four seasons, and calculating the normalized value of the 24-hour confidence output in four seasons of typical days; given the total installed capacity of distributed power sources, calculating the 24-hour confidence output value in four seasons of typical days; and performing four seasons power tight balancing respectively based on the 24-hour confidence output, 24-hour load, conventional power output and current power supply capacity of the distributed power sources in four seasons, and obtaining a demand curve for the power supply capacity to be newly added.

Description

Technical Field

[0001] The present invention relates to the technical field of power grid planning, and in particular to a power distribution network tight balancing method based on distributed power source output timing. Background Art

[0002] In order to implement the supply-side structural reform deployment, implement the State-owned Assets Supervision and Administration Commission's cost reduction and expenditure reduction, improve quality and efficiency, enhance the company's operating performance, and ensure the sustainable development of the power grid, State Grid Corporation of China issued the "Notice on Further Strict Control of Power Grid Investment" (State Grid Office

[2019] No. 826). The document proposes the investment and construction ideas of "three strict prohibitions, two prohibitions, and two no longer", and proposes to fully recognize the importance and urgency of strict control of power grid investment; determine investment based on output and strictly control the scale of power grid investment; focus on loss management, and no longer make new investments in loss-making units; focus on efficiency and benefits, and strengthen power grid investment management.

[0003] The power balance of traditional power grid planning has two main characteristics. One is to meet the power balance of the peak maximum load of the entire network at a single moment, and the other is that distributed power sources do not participate in the balance. Due to the large-scale access of distributed power sources and the emergence of multiple loads, the maximum values ​​of superimposed output and load have changed significantly and cannot be expressed by the traditional single-point balance method. The overall performance of traditional power balance is "loose balance", which requires a large amount of power grid capital investment, but the peak load duration is short, resulting in low overall equipment utilization efficiency. In the context of tight investment in the power grid, the traditional method is unsustainable.

[0004] There is currently no effective solution to the above technical problems. Summary of the invention

[0005] In response to the above-mentioned technical problems in the related technologies, the present invention proposes a distribution network power tight balancing method based on the output timing of distributed power sources, which can solve the problems of huge power grid investment and low equipment utilization efficiency caused by the traditional method of not considering the contribution of distributed power sources and taking the annual maximum load as the power balance standard, thereby realizing the global optimization planning problem.

[0006] To achieve the above technical objectives, the technical solution of the present invention is implemented as follows:

[0007] A method for tight power balancing of a distribution network based on a distributed power generation output timing sequence comprises the following steps:

[0008] S1: Extract the daily 24-hour active load value of the transformer in the past 1-3 years, cluster and form the characteristic curves of typical days in four seasons for each type of load according to the different types of transformer power supply load, and calculate the normalized value of the 24-hour load on typical days in four seasons;

[0009] S2: Use the spatial load density method to predict the typical daily load values ​​of various types of land plots in four seasons. According to the normalized 24-hour load value of the typical day in four seasons calculated in step S1, calculate the corresponding 24-hour load value, and superimpose the 24-hour load value of the typical day in four seasons in the region;

[0010] S3: Extract the daily 24-hour output values ​​of distributed power sources in the past 1-3 years, set the initial value of the confidence probability of distributed power output, cluster to form the characteristic curve of typical confidence output in four seasons, and calculate the normalized value of the typical daily 24-hour confidence output in four seasons;

[0011] S4: Given the total installed capacity of distributed power sources, calculate the 24-hour confidence output value of typical days in four seasons according to the confidence output normalization value calculated in step S3;

[0012] S5: Based on the 24-hour confidence output of distributed power sources on typical days in four seasons, 24-hour load, conventional power output and current power supply capacity, four-season power tight balancing is performed to calculate the characteristic curve of the demand for additional power supply capacity.

[0013] Furthermore, in step S1, the transformer power supply load categories include residential, commercial, administrative office, and industrial.

[0014] Furthermore, in step S1 and step S3, the clustering method includes K-Means clustering method and mean shift clustering method.

[0015] Furthermore, in step S1, the calculation formula for the 24-hour load normalization value of a typical day in four seasons is:

[0016] The normalized load value at a certain point in time = the load value at a certain point in time / the maximum load value of the day.

[0017] Furthermore, in step S2, the calculation formula for the typical daily load value of the plot in four seasons is:

[0018] The typical daily load value of the plot in four seasons = the building area of ​​the plot × the load density per unit building area.

[0019] Furthermore, in step S3, the distributed power source includes photovoltaic power and wind power.

[0020] Among them, in the step S3, the initial value of the confidence probability is the confidence probability that the distributed power output participates in the balance, which is 90% or above.

[0021] Furthermore, in step S4, the calculation steps of the 24-hour confidence output value of a typical day in four seasons are as follows:

[0022] S41: Statistics on the total installed capacity of various types of distributed power sources;

[0023] S42: Calculate the 24-hour confidence output value for typical days in four seasons. The calculation formula used is as follows:

[0024] The confidence output value at a certain point in time = the total installed capacity of this type of distributed power generation × the theoretical maximum output ratio × the normalized value of the confidence output of this type of typical day in four seasons for 24 hours.

[0025] Furthermore, in step S5, the steps for acquiring the new power supply capacity demand characteristic curve are as follows:

[0026] S51: Evaluate the current power supply capacity of the regional power grid. According to the power supply safety standards of the power grid, the power supply capacity of a 110kV substation should be the power supply capacity without load loss when any main transformer fails. The calculation formula for the power supply capacity of a 110kV substation is:

[0027] The power supply capacity of a 110kV substation = the substation capacity - the capacity of the largest main transformer;

[0028] The power supply capacity of a 10kV feeder is that there is no load loss when any feeder in the feeder group loses power. The calculation formula for the power supply capacity of a medium-voltage feeder is:

[0029] 10kV feeder power supply capacity = current power factor × (total maximum transmission capacity of feeders in feeder group - maximum transmission capacity of a single feeder) / number of feeder groups;

[0030] S52: Calculate the additional power supply capacity required by the 110kV power grid at a certain moment. The calculation formula is:

[0031] The additional power supply capacity required by the regional 110kV power grid at a certain moment = the load forecast value at that moment - the confidence output value of the low-voltage distributed power supply at that moment - the stable power output value of the low-voltage grid at that moment - the load of 110kV and above dedicated line users at that moment - the current 110kV power supply capacity of the power grid,

[0032] Among them, the current 110kV power grid power supply capacity = the cumulative power supply capacity of 110kV substations in the region;

[0033] S53: Calculate the additional power supply capacity required by the 10kV power grid at a certain moment. The calculation formula is:

[0034] The power supply capacity required by the 10kV power grid in the region at a certain moment = the load forecast value at that moment - the confidence output value of the low-voltage distributed power supply at that moment - the stable power output value of the low-voltage grid at that moment - the load of 10kV and above dedicated line users at that moment - the current 10kV feeder power supply capacity,

[0035] Among them, the current 10kV feeder power supply capacity = the cumulative sum of 10kV feeder power supply capacities in the region;

[0036] S54: Filter the maximum value of the capacity increment curve required for 24 hours in typical days in four seasons, calculate the number of substations and medium-voltage feeder lines to be added, and obtain the characteristic curve of the power supply capacity demand to be added.

[0037] The number of newly built 110kV substations = the maximum value of the new power supply capacity required by the 110kV power grid in the region at a certain time / the typical configuration capacity of 110kV substations,

[0038] Among them, the typical configuration capacity of 110kV substation is 100MVA;

[0039] The number of additional 10kV feeder lines required = the maximum power supply capacity of the 10kV power grid in the region at a certain time / the transmission capacity of a single feeder line,

[0040] Among them, the transmission capacity of a single feeder line is 4MVA according to the typical LGJ-240 safe transmission capacity.

[0041] The beneficial effects of the present invention are as follows: the present invention forms four-season typical daily characteristic curves of various types of loads through clustering to obtain load normalization values; draws load characteristic curves based on saturated load predictions of plots with different load properties, and superimposes them to form regional four-season typical daily hourly load values; forms four-season confident output characteristic curves of distributed power sources through clustering to obtain output normalization values; considers the distributed power source confident output, conventional power source output, and load, and calculates the power balance of a 24-hour section on a typical day in four seasons, thereby solving the problems of huge power grid investment and low equipment utilization efficiency caused by the traditional method of not considering the contribution of distributed power source output and taking the annual maximum load as the power balance standard, thereby realizing the planning problem of global optimization. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0043] Figure 1 It is a flow chart of a method for tight power balancing of a distribution network based on a distributed power source output timing according to an embodiment of the present invention;

[0044] Figure 2 A typical daily power consumption characteristic curve of commercial loads in summer according to a power distribution network power tight balancing method based on distributed power generation output timing according to an embodiment of the present invention;

[0045] Figure 3A summer distributed photovoltaic confidence output characteristic curve of a distribution network power tight balancing method based on a distributed power source output timing according to an embodiment of the present invention;

[0046] Figure 4 A typical daily output characteristic curve of distributed photovoltaic power in summer according to a method for tight power balance of a distribution network based on a distributed power source output timing according to an embodiment of the present invention;

[0047] Figure 5 It is a characteristic curve of the demand for additional power supply capacity based on the tight balance calculation result of a distribution network power tight balance method based on the output timing of distributed power sources according to an embodiment of the present invention. DETAILED DESCRIPTION

[0048] The following will be combined with the accompanying drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. 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 belong to the scope of protection of the present invention.

[0049] like Figure 1 As shown, a power distribution network power tight balancing method based on distributed power output timing according to an embodiment of the present invention includes the following steps:

[0050] S1: Extract the daily 24-hour active load value of the transformer in the past 1-3 years, cluster and form the characteristic curves of typical days in four seasons for each type of load according to the different types of transformer power supply load, and calculate the normalized value of the 24-hour load on typical days in four seasons;

[0051] S2: Use the spatial load density method to predict the typical daily load values ​​of various types of land plots in four seasons. According to the normalized 24-hour load value of the typical day in four seasons calculated in step S1, calculate the corresponding 24-hour load value, and superimpose the 24-hour load value of the typical day in four seasons in the region;

[0052] S3: Extract the daily 24-hour output values ​​of distributed power sources in the past 1-3 years, set the initial value of the confidence probability of distributed power output, cluster to form the characteristic curve of typical confidence output in four seasons, and calculate the normalized value of the typical daily 24-hour confidence output in four seasons;

[0053] S4: Given the total installed capacity of distributed power sources, calculate the 24-hour confidence output value of typical days in four seasons according to the confidence output normalization value calculated in step S3;

[0054] S5: Based on the 24-hour confidence output of distributed power sources on typical days in four seasons, 24-hour load, conventional power output and current power supply capacity, four-season power tight balancing is performed to calculate the characteristic curve of the demand for additional power supply capacity.

[0055] In a specific embodiment, in step S1, the transformer power supply load categories include residential, commercial, administrative office, and industrial.

[0056] In a specific embodiment, in step S1 and step S3, the clustering method includes K-Means clustering method and mean shift clustering method.

[0057] In a specific embodiment, if Figure 2 As shown, in step S1, the calculation formula for the 24-hour load normalization value of a typical day in four seasons is:

[0058] The normalized load value at a certain point in time = the load value at a certain point in time / the maximum load value of the day.

[0059] In a specific embodiment, in step S2, the calculation formula for the typical daily load value of the plot in four seasons is:

[0060] The typical daily load value of the plot in four seasons = the building area of ​​the plot × the load density per unit building area.

[0061] Preferably, the value of load density per unit building area can be selected by referring to the "Technical Guidelines for Distribution Network Planning and Design" DL / T5729-2016 or other relevant local guidelines.

[0062] In a specific embodiment, in step S3, the distributed power source includes photovoltaic power and wind power.

[0063] Preferably, in step S3, the initial value of the confidence probability is the confidence probability that the distributed power source output participates in the balance, which is generally 90% or above.

[0064] In a specific embodiment, if Figure 3 As shown, in step S4, the calculation steps of the 24-hour confidence output value of a typical day in four seasons are as follows:

[0065] S41: Statistics on the total installed capacity of various types of distributed power sources;

[0066] S42: Calculate the 24-hour confidence output value for typical days in four seasons. The calculation formula used is as follows:

[0067] The confidence output value at a certain point in time = the total installed capacity of this type of distributed power supply × the theoretical maximum output ratio × the normalized confidence output value of the typical day in four seasons for 24 hours.

[0068] Among them, the normalized value of the 24-hour confidence output of a typical day in four seasons = the 24-hour confidence output value of a typical day in four seasons / the maximum daily output. The daily output value is as follows: Figure 4 shown.

[0069] Preferably, the theoretical maximum output ratio is 90% in winter, 95% in summer, and 97% in spring and autumn.

[0070] In a specific embodiment, in step S5, the steps of acquiring the new power supply capacity demand characteristic curve are as follows:

[0071] S51: Evaluate the current power supply capacity of the regional power grid. According to the power supply safety standards of the power grid, the power supply capacity of a 110kV substation should be the power supply capacity without load loss when any main transformer fails. The calculation formula for the power supply capacity of a 110kV substation is:

[0072] The power supply capacity of a 110kV substation = the substation capacity - the capacity of the largest main transformer;

[0073] The power supply capacity of a 10kV feeder is that there is no load loss when any feeder in the feeder group loses power. The calculation formula for the power supply capacity of a medium-voltage feeder is:

[0074] 10kV feeder power supply capacity = current power factor × (total maximum transmission capacity of feeders in feeder group - maximum transmission capacity of a single feeder) / number of feeder groups;

[0075] S52: Calculate the additional power supply capacity required by the 110kV power grid at a certain moment. The calculation formula is:

[0076] The additional power supply capacity required by the regional 110kV power grid at a certain moment = the load forecast value at that moment - the confidence output value of the low-voltage distributed power supply at that moment - the stable power output value of the low-voltage grid at that moment - the load of 110kV and above dedicated line users at that moment - the current 110kV power supply capacity of the power grid,

[0077] Among them, the current 110kV power grid power supply capacity = the cumulative power supply capacity of 110kV substations in the region;

[0078] S53: Calculate the additional power supply capacity required by the 10kV power grid at a certain moment. The calculation formula is:

[0079] The power supply capacity required by the 10kV power grid in the region at a certain moment = the load forecast value at that moment - the confidence output value of the low-voltage distributed power supply at that moment - the stable power output value of the low-voltage grid at that moment - the load of 10kV and above dedicated line users at that moment - the current 10kV feeder power supply capacity,

[0080] Among them, the current 10kV feeder power supply capacity = the cumulative sum of 10kV feeder power supply capacities in the region;

[0081] S54: Filter the maximum value of the capacity increment curve required for 24 hours in typical days in four seasons, calculate the number of substations and medium-voltage feeder lines to be added, and obtain the characteristic curve of the power supply capacity required to be added, such as Figure 5As shown,

[0082] The number of newly built 110kV substations = the maximum value of the new power supply capacity required by the 110kV power grid in the region at a certain time / the typical configuration capacity of 110kV substations,

[0083] Among them, the typical configuration capacity of 110kV substation is 100MVA;

[0084] The number of additional 10kV feeder lines required = the maximum power supply capacity of the 10kV power grid in the region at a certain time / the transmission capacity of a single feeder line,

[0085] Among them, the transmission capacity of a single feeder line is based on the typical LGJ-240 safe transmission capacity, while taking into account the satisfaction of N-1 verification, and is generally 4MVA.

[0086] In order to facilitate understanding of the above technical solutions of the present invention, the above technical solutions of the present invention are described in detail below through specific usage methods.

[0087] In specific use, according to the method for power tight balancing of distribution network based on distributed power output timing of the present invention, it is first necessary to collect various historical power supply load values, form characteristic curves of typical days of various loads in four seasons by clustering methods such as K-Means clustering method and mean shift clustering method, and calculate the load normalization value; then predict the maximum load value of typical day of four seasons of various plots, calculate the corresponding daily hourly load value according to the calculated load normalization value, and superimpose the typical daily hourly load value of four seasons of various load calculation areas; then continue to collect the daily hourly output values ​​of distributed power sources in history, form characteristic curves of typical day of four seasons confidence output by clustering methods such as K-Means clustering method and mean shift clustering method, and calculate the confidence output normalization value; the total installed capacity of distributed power sources is known, and the confidence output value of typical day of four seasons in 24 hours of the region is calculated according to the calculated confidence output normalization value; finally, based on the 24-hour confidence output of typical day of four seasons of distributed power sources, the daily 24-hour load, the output of conventional power sources and the current power supply capacity, the four seasons power tight balance calculation is performed to obtain the characteristic curve of the power supply capacity to be added. Based on this method, planning technicians and enterprise managers can be provided with a decision-making basis for optimized planning and achieve precise investment.

[0088] In summary, the present invention proposes a distribution network power tight balancing method based on the output timing of distributed power sources, so as to solve the problems of huge power grid investment and low equipment utilization efficiency caused by the traditional method of not considering the contribution of distributed power sources and taking the annual maximum load as the power balancing standard, thereby realizing the global optimization planning problem.

[0089] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for tight power balancing of a distribution network based on the output timing of distributed power sources, characterized in that: The steps include: S1: Extract the daily 24-hour active load value of the transformer in the past 1-3 years, cluster and form the characteristic curves of typical days in four seasons for each type of load according to the different types of transformer power supply load, and calculate the normalized value of the 24-hour load on typical days in four seasons; S2: Use the spatial load density method to predict the typical daily load values ​​of various types of land plots in four seasons. According to the normalized 24-hour load value of the typical day in four seasons calculated in step S1, calculate the corresponding 24-hour load value, and superimpose the 24-hour load value of the typical day in four seasons in the region; S3: Extract the daily 24-hour output values ​​of distributed power sources in the past 1-3 years, set the initial value of the confidence probability of distributed power output, cluster to form the characteristic curve of typical confidence output in four seasons, and calculate the normalized value of the typical daily 24-hour confidence output in four seasons; S4: Given the total installed capacity of distributed generation, calculate the 24-hour confidence output value of typical days in four seasons according to the confidence output normalization value calculated in step S3; S5: Based on the 24-hour confidence output, 24-hour load, conventional power output and current power supply capacity of the distributed power generation in four seasons, four seasons of power tight balance are performed to calculate the demand characteristic curve of the additional power supply capacity; In step S5, the steps for acquiring the new power supply capacity demand characteristic curve are as follows: S51: Evaluate the current power supply capacity of the regional power grid. According to the power supply safety standards of the power grid, the power supply capacity of a 110kV substation should be the power supply capacity without load loss when any main transformer fails. The calculation formula for the power supply capacity of a 110kV substation is: The power supply capacity of a 110kV substation = the substation capacity - the capacity of the largest main transformer; The power supply capacity of a 10kV feeder is that there is no load loss when any feeder in the feeder group loses power. The calculation formula for the power supply capacity of a medium-voltage feeder is: 10kV feeder power supply capacity = current power factor × (total maximum transmission capacity of feeders in feeder group - maximum transmission capacity of a single feeder) / number of feeder groups; S52: Calculate the additional power supply capacity required by the 110kV power grid at a certain moment. The calculation formula is: The additional power supply capacity required by the regional 110kV power grid at a certain moment = the load forecast value at that moment - the confidence output value of the low-voltage distributed power supply at that moment - the stable power output value of the low-voltage grid at that moment - the load of 110kV and above dedicated line users at that moment - the current 110kV power supply capacity of the power grid, Among them, the current 110kV power grid power supply capacity = the cumulative power supply capacity of 110kV substations in the region; S53: Calculate the additional power supply capacity required by the 10kV power grid at a certain moment. The calculation formula is: The power supply capacity required by the 10kV power grid in the region at a certain moment = the load forecast value at that moment - the confidence output value of the low-voltage distributed power supply at that moment - the stable power output value of the low-voltage grid at that moment - the load of 10kV and above dedicated line users at that moment - the current 10kV feeder power supply capacity, Among them, the current 10kV feeder power supply capacity = the cumulative sum of 10kV feeder power supply capacities in the region; S54: Filter the maximum value of the capacity increment curve required for 24 hours in typical days in four seasons, calculate the number of substations and medium-voltage feeder lines to be added, and obtain the characteristic curve of the power supply capacity demand to be added. The number of newly built 110kV substations = the maximum value of the new power supply capacity required by the 110kV power grid in the region at a certain time / the typical configuration capacity of 110kV substations, Among them, the typical configuration capacity of 110kV substation is 100MVA; The number of additional 10kV feeder lines required = the maximum power supply capacity of the 10kV power grid in the region at a certain time / the transmission capacity of a single feeder line, Among them, the transmission capacity of a single feeder line is 4MVA according to the typical LGJ-240 safe transmission capacity.

2. A method for tight power balancing of a distribution network based on the output timing of distributed power sources according to claim 1, characterized in that: In step S1, the transformer power supply load categories include residential, commercial, administrative office, and industrial.

3. According to claim 1, a method for tight power balancing of a distribution network based on the output timing of distributed power sources is characterized in that: In step S1 and step S3, the clustering method includes K-Means clustering method and mean shift clustering method.

4. The method for tight power balancing of a distribution network based on the output timing of distributed power sources according to claim 1, characterized in that: In step S1, the calculation formula for the 24-hour load normalization value of a typical day in four seasons is: The normalized load value at a certain point in time = the load value at a certain point in time / the maximum load value of the day.

5. The method for tight power balancing of a distribution network based on the output timing of distributed power sources according to claim 1, characterized in that: In step S2, the calculation formula for the typical daily load value of the plot in four seasons is: The typical daily load value of the plot in four seasons = the building area of ​​the plot × the load density per unit building area.

6. A method for tight power balancing of a distribution network based on the output timing of distributed power sources according to claim 1, characterized in that: In step S3, the distributed power source includes photovoltaic power and wind power.

7. A method for tight power balancing of a distribution network based on the output timing of distributed power sources according to any one of claims 1 or 6, characterized in that: In step S3, the initial value of the confidence probability is the confidence probability that the distributed power output participates in balancing, which is 90% or above.

8. The method for tight power balancing of a distribution network based on the output timing of distributed power sources according to claim 1, characterized in that: In step S4, the calculation steps of the 24-hour confidence output value of a typical day in four seasons are as follows: S41: Statistics on the total installed capacity of various types of distributed power sources; S42: Calculate the 24-hour confidence output value for typical days in four seasons. The calculation formula used is as follows: The confidence output value at a certain point in time = the total installed capacity of this type of distributed power generation × the theoretical maximum output ratio × the normalized confidence output value of this type of typical day in four seasons for 24 hours.

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