Method, system and equipment for planning transformer substation connected with high-permeability distributed power supply

Abstract

The invention discloses a method for planning a transformer substation connected with a high-permeability distributed power supply, and the method comprises the steps: obtaining the optimal number of main transformers and the capacity of the transformer substation corresponding to the minimum cost through constructing a transformer substation capacity probability planning model, and calculating the investment cost of all combinations in the capacity range through a simple enumeration method; calculating to obtain DG permeability, DG critical permeability, load permeability and load critical permeability through load and output data in a planning area, judging a DG credibility typical value calculation mode through the data, and finally obtaining DG capacity credibility. And the total capacity demand of the public power transformation can be obtained through the ratio of the capacity to the maximum output in power balance. According to the design, the transformer substation capacity probability planning model can be rapidly solved through a simple enumeration method, the transformer substation capacity corresponding to the optimal number of main transformers and the minimum cost is obtained, and the feasibility of the transformer substation planning method can be effectively improved by judging a DG credibility typical value calculation mode.

Description

Technical Field

[0001] The present invention relates to a substation planning method, and in particular to a substation planning method, system and device connected to a high-penetration distributed power source. Background Art

[0002] Compared with traditional thermal power generation with controllable output, the output fluctuation of power supply side is stronger due to the high installed capacity, low power, randomness and difficulty in regulation of new energy. With the access of a large number of distributed power sources (DG) with new energy as the main body to the distribution network, the scientific and reasonable selection of substation site and capacity is increasingly affected by various factors. As for the effect of DG on substation capacity selection, most of the current research is based on reliability or probability to carry out confidence capacity analysis.

[0003] In actual active distribution network planning, planners generally use power balance to determine the scale of the grid, and it is difficult to directly use confidence to consider the role of DG in the planning results of the distribution network. The reason is that the scale of the distribution network is not only affected by DG, but also related to other distributed resources. In the power balance that combines the influence of other distributed resources, it is extremely important to consider the impact of the volatility of DG output that is difficult to control, such as wind and solar. This leads to the concept of DG credibility, that is, the ratio of the reasonable capacity that DG should use in power balance to its capacity / maximum output.

[0004] Although this traditional substation capacity planning method can effectively ensure the utilization efficiency and input-output benefits of distribution network assets, it still has the following defects:

[0005] 1. The existing substation capacity planning method does not take into account the DG high penetration scenario or DG power abandonment loss, resulting in unreasonable substation capacity planning, insufficient planned capacity, and resulting in power generation energy loss and power abandonment loss.

[0006] 2. The existing substation capacity planning method does not take into account the volatility of DG output such as wind and solar power, which is difficult to control. Its planning method is generally applicable to traditional power generation conditions and cannot adapt to the regulation of DG output volatility for renewable energy power generation.

[0007] 3. Due to the randomness of DG output, the traditional calculation method requires too much calculation and the substation planning efficiency is low.

[0008] The information disclosed in this background technology section is only intended to increase the understanding of the overall background of the application, and should not be regarded as acknowledging or suggesting in any form that the information constitutes the prior art already known to ordinary technicians in this field. Summary of the invention

[0009] The purpose of the present invention is to overcome the shortcomings of poor comprehensiveness and low efficiency of substation planning in the prior art, and to provide a substation planning method, system and equipment for accessing high-penetration distributed power sources with high comprehensiveness and high efficiency of substation planning.

[0010] To achieve the above objectives, the technical solution of the present invention is:

[0011] A method for planning a substation connected to a high-penetration distributed power source, the substation capacity planning method comprising:

[0012] S1, set the substation capacity as a variable, take the annual cost of substation investment related to the capacity and the total cost consisting of load power outage / DG power abandonment loss cost caused by the main transformer outage as the objective function, and construct a probabilistic planning model for substation capacity. The expression of the probabilistic planning model for substation capacity is:

[0013]

[0014] In the above formula, F Z is the total cost, F T is the annual cost of substation investment, F Q is the DG power abandonment fee, F K is the power outage loss cost, S Z is the total capacity of a single substation, n Z The number of main transformers, S d is the capacity of a single main transformer, ψ is the allowable DG power abandonment rate under normal conditions, P L，k is the comprehensive load size of the planning area in the kth period, P G，i，k is the output value of the i-th DG output state combination in the k-th period, X h is the number of time periods, X s The number of new energy output state combinations;

[0015] S2, solves the substation capacity probability planning model constructed in S1 to obtain the optimal number of main transformers and substation capacity;

[0016] S3, calculate the DG permeability, DG critical permeability, load permeability and load critical permeability through the load and output data in the planning area, select the DG credibility typical value calculation mode by comparing the DG permeability, DG critical permeability, load permeability and load critical permeability, and calculate the DG credibility typical value based on the selected calculation mode and the model solution result;

[0017] S4, the total capacity demand of public substation is calculated by the typical value of DG credibility, so as to obtain a substation planning scheme, wherein the substation planning scheme includes the total capacity demand of public substation, the optimal number of main transformers and the substation capacity.

[0018] In S1, the annual cost of substation investment F T The corresponding formula is obtained by linearly fitting the annual investment cost of substations with different capacities, and its expression is:

[0019] F T =ε(a+bS z );

[0020] In the above formula, ε=α+β+γ, wherein α is the maintenance rate, β is the return on investment, γ is the depreciation rate, a is a coefficient that is independent of capacity, and b is a coefficient that is related to capacity.

[0021] In S1, the power outage loss fee F K The expression is:

[0022] F K =F K，1 +F K，2 ;

[0023] In the above formula, F K，1 F is the power outage loss cost in the first stage, K，2 Cost of power outage losses during Phase 2;

[0024] The first stage power outage loss cost F K，1 And the second stage power outage loss cost F K，2 The expression is:

[0025]

[0026]

[0027] In the above formula, r b1 is the short-term power outage time of the main transformer, λ s，t is the planned maintenance rate of the main transformer, r s，t The planned outage time of the main transformer, Ω e is the set of single fault components that cause a single main transformer to lose power, λ f，e Ω e The failure rate of the e-th component in f，e is the fault outage time of the e-th component, c s The cost of planned power outages, c f The cost of power outage due to fault, P ki，1 is the power shortage power in the first stage of the i-th DG output state in time period k, P ki，2 is the power shortage power in the second stage of the i-th DG output state in time period k;

[0028] The power shortage power P of the first stage of the i-th DG output state in the k-th time period ki，1And the power shortage power P in the second stage ki，2 The expression is:

[0029]

[0030]

[0031] In the above formula, is the power factor of the power flowing through the substation, p i is the probability of the i-th DG output state, α zj It is the correction factor for the impact of inter-station load transfer on the strain power station DG. When the inter-station load transfer of the substation has no impact on the strain power station, α zj =0, when the load transfer between substations has the same impact on the DG of the substation and the local station α zj =1, K zg，1 is the safety load factor of the first stage, K zg，2 is the safe load factor for stage 2;

[0032] The safe load factor K of the first stage zg，1 And the second stage safety load factor K zg，2 The expression is:

[0033]

[0034] In the above formula, n z is the number of main transformers, K zn K is the maximum main transformer load rate that can be transferred within the station when there is no DG. zj It is the maximum main transformer load rate that can be transferred between stations when there is no DG.

[0035] In S1, the DG power abandonment fee F Q The expression is:

[0036] F Q =F Q，1 +F Q，2 ;

[0037] In the above formula, F Q，1 is the DG power curtailment cost in the first stage, F Q，2 It is the cost of DG power abandonment in the second stage;

[0038] The first stage DG power curtailment cost F Q，1 and the second stage DG power curtailment fee F Q，2 The expression is:

[0039]

[0040]

[0041] In the above formula, C C Penalty fee for DG power abandonment.

[0042] The S2 comprises the following steps:

[0043] S2.1, divide the substation power supply area into N a Part, determine the maximum load P1 of the substation power supply area max ;

[0044] S2.2, divide 24 hours a day into X h The corresponding daily load curve and P 1max Calculate the load P of the substation supply area in the kth period L，k ;

[0045] S2.3, calculate the output value P of the i-th DG output state combination in the k-th period G，i，k and its probability p i ;

[0046] S2.4, determine the combination of the number of substations and their capacity range, and select the substation capacity to meet the formula |P in the substation capacity probability planning model L，k -(1-ψ)P G，i，k |≤S z The minimum capacity is taken as the initial value, and incremented by the set step size ΔS to obtain the total capacity S of a single substation under different combinations of units. z ;

[0047] S2.5, calculate the investment cost F of all combinations of units within their capacity range T ;

[0048] S2.6, based on the load P of the substation supply area in the kth period L，k , the output value P of the i-th DG output state combination in the k-th period G，i，k , probability p i and capacity range, calculate the main transformer outage loss cost F for all combined capacity ranges K and DG power abandonment loss cost F Q ;

[0049] S2.7, calculate the F corresponding to each combination of main transformer numbers T 、F K and F Q Substitute it into the substation capacity probability planning model, calculate and compare the total cost of each combination of main transformer numbers, and select the one that makes the objective function F Z The combination method with the minimum number of substations and capacities, thus obtaining the optimal number of main transformers xz and the total capacity of the substation S z, then output the optimal number of main transformers n z and the optimal substation total capacity S z As substation capacity S opt .

[0050] In S3, the DG permeability δ dg and DG critical permeability δ dg，c The expression is:

[0051]

[0052] The load permeability δ fh And the critical load permeability δ when the output of new energy remains constant fh，c The expression is:

[0053]

[0054] In the above formula, P zx，fmax P is the comprehensive grid load corresponding to the maximum forward power of the transformer equipment in the planning area. gmax is the maximum output of random renewable energy in the planning area, P fm is the maximum reverse power, P zm is the maximum forward power, and the maximum reverse power P fm Equal to the maximum forward power P zm The DG permeability is defined as the DG critical permeability δ when the grid supply comprehensive load remains unchanged dg，c ;

[0055] The maximum reverse power P fm And the maximum forward power P zm The expression is:

[0056]

[0057] In the above formula, P L，k is the comprehensive load size of the planning area in the kth period, P G，i，k is the output value of the i-th DG output state combination in the k-th period;

[0058] The judgment basis of the DG credibility typical value calculation mode is as follows: when the DG penetration rate is lower than the DG critical penetration rate or the load penetration rate is greater than the load critical penetration rate, the load power balance mode is used to calculate the DG credibility typical value; when the DG penetration rate is higher than the DG critical penetration rate or the load penetration rate is less than the load critical penetration rate, the power supply power balance mode should be used to calculate the DG credibility typical value;

[0059] In the load power balancing mode, calculation and analysis of typical values ​​of DG credibility are carried out based on one of different load densities or maximum loads and different DG penetration conditions;

[0060] In the power balance mode, the calculation and analysis of the typical value of DG credibility is carried out based on different power density or one of the maximum DG outputs and different load penetration conditions.

[0061] The expression of the typical value formula of DG credibility in S3 is:

[0062]

[0063] In the above formula, σ c，2 is the typical value of DG credibility, λ c，2 is the capacity confidence level;

[0064] The capacity confidence λ c，2 The expression is

[0065]

[0066] In the above formula, S opt is the substation capacity obtained by solving the substation capacity probability planning model, S opt,0 is the substation capacity calculated using the probability planning method when the DG output is zero, S opt,1 It is the substation capacity calculated by the probabilistic planning method when only the maximum DG typical output curve state is adopted.

[0067] In S4, the total capacity requirement of public substation under load power balance S bz The expression is:

[0068] S bz =(K r -σ c，2 δ dg K g ) zx，fmax ;

[0069] The power supply balances the total capacity demand of the public substation S bz The expression is:

[0070] S bz =(σ c，2 K g -δ fh K r ) gmax ;

[0071] In the above formula, K r is the load operation factor, K g is the power generation operation coefficient, σ c，2 is the typical value of DG credibility.

[0072] A substation planning system for accessing a high-penetration distributed power source, the substation planning system for accessing a high-penetration distributed power source comprising:

[0073] Model building module, used to build a substation capacity probabilistic planning model by:

[0074] The substation capacity is set as a variable, and the total cost consisting of the annual substation investment cost related to the capacity and the load power outage / DG power abandonment loss cost caused by the main transformer outage is minimized as the objective function. A probabilistic planning model for substation capacity is constructed. The expression of the probabilistic planning model for substation capacity is:

[0075]

[0076] In the above formula, F Z is the total cost, F T is the annual cost of substation investment, F Q is the DG power abandonment fee, F K is the power outage loss cost, S Z is the total capacity of a single substation, n Z The number of main transformers, S d is the capacity of a single main transformer, ψ is the allowable DG power abandonment rate under normal conditions, P L，k is the comprehensive load size of the planning area in the kth period, P G，i，k is the output value of the i-th DG output state combination in the k-th period, X h is the number of time periods, X s The number of new energy output state combinations;

[0077] The annual cost of substation investment The annual cost of substation investment F T The corresponding formula is obtained by linearly fitting the annual investment cost of substations with different capacities, and its expression is:

[0078] F T =ε(a+bS z );

[0079] In the above formula, ε=α+β+γ, wherein α is the maintenance rate, β is the return on investment, γ is the depreciation rate, a is a coefficient that is independent of capacity, and b is a coefficient that is related to capacity.

[0080] The power outage loss cost F K The expression is:

[0081] F K =F K，1 +F K，2 ;

[0082] In the above formula, F K，1F is the power outage loss cost in the first stage, K，2 Cost of power outage losses during Phase 2;

[0083] The first stage power outage loss cost F K，1 And the second stage power outage loss cost F K，2 The expression is:

[0084]

[0085]

[0086] In the above formula, r b1 is the short-term power outage time of the main transformer, λ s，t is the planned maintenance rate of the main transformer, r s，t The planned outage time of the main transformer, Ω e is the set of single fault components that cause a single main transformer to lose power, λ f，e Ω e The failure rate of the e-th component in f，e is the fault outage time of the e-th component, c s The cost of planned power outages, c f The cost of power outage due to fault, P ki，1 is the power shortage power in the first stage of the i-th DG output state in time period k, P ki，2 is the power shortage power in the second stage of the i-th DG output state in time period k;

[0087] The power shortage power P of the first stage of the i-th DG output state in the k-th time period ki，1 And the power shortage power P in the second stage ki，2 The expression is:

[0088]

[0089]

[0090] In the above formula, is the power factor of the power flowing through the substation, P i is the probability of the i-th DG output state, α zj It is the correction factor for the impact of inter-station load transfer on the strain power station DG. When the inter-station load transfer of the substation has no impact on the strain power station, α zj =0, when the load transfer between substations has the same impact on the DG of the substation and the local station α zj =1, K zg，1 is the safety load factor of the first stage, K zg，2 is the safe load factor for stage 2;

[0091] The safe load factor K of the first stage zg，1 And the second stage safety load factor K zg，2 The expression is:

[0092]

[0093] In the above formula, n z is the number of main transformers, K zn K is the maximum main transformer load rate that can be transferred within the station when there is no DG. zj It is the maximum main transformer load rate that can be transferred between stations when there is no DG.

[0094] The DG power curtailment fee F Q The expression is:

[0095] F Q =F Q，1 +F Q，2 ;

[0096] In the above formula, F Q，1 is the DG power curtailment cost in the first stage, F Q,2 It is the cost of DG power abandonment in the second stage;

[0097] The first stage DG power curtailment cost F Q， DG power curtailment fee F in stage 1 and 2 Q，2 The expression is:

[0098]

[0099]

[0100] In the above formula, C C Penalty fee for DG power abandonment.

[0101] The model solving module is used to obtain the optimal number of main transformers and the substation capacity corresponding to the minimum cost through the following methods:

[0102] The substation power supply area is divided into N a Part, determine the maximum load P of the substation power supply area 1max ;

[0103] Divide 24 hours of a day into X h The corresponding daily load curve and P 1max Calculate the load P of the substation supply area in the kth period L，k ;

[0104] Count the output value P of the i-th DG output state combination in the k-th period G，i，k and its probability p i ;

[0105] Determine the combination of the number of substations and their capacity range, and select the substation capacity to meet the formula |P in the substation capacity probability planning model L，k -(1-ψ)P G，i，k |≤S z The minimum capacity is taken as the initial value, and incremented by the set step size ΔS to obtain the total capacity S of a single substation under different combinations of units. z ;

[0106] Calculate the investment cost F for all combinations of units within their capacity range T ;

[0107] Based on the load P of the kth period in the substation supply area L，k , the output value P of the i-th DG output state combination in the k-th period G，i，k , probability p i and capacity range, calculate the main transformer outage loss cost F for all combined capacity ranges K and DG power abandonment loss cost F Q ;

[0108] The F corresponding to each combination of main transformer numbers is calculated. T 、F K and F Q Substitute it into the substation capacity probability planning model, calculate and compare the total cost of each combination of main transformer numbers, and select the one that makes the objective function F Z The combination method with the minimum number of substations and capacities, thus obtaining the optimal number of main transformers n z and the total capacity of the substation S z , then output the optimal number of main transformers n z and the optimal substation total capacity S z As substation capacity S opt .

[0109] The DG credibility typical value calculation module is used to calculate the DG permeability, DG critical permeability, load permeability and load critical permeability through the load and output data in the planning area, select the DG credibility typical value calculation mode by comparing the DG permeability, DG critical permeability, load permeability and load critical permeability, and calculate the DG credibility typical value based on the selected calculation mode and the model solution results; the specific method is as follows:

[0110] The expression of the typical value formula of DG credibility is:

[0111]

[0112] In the above formula, σ c，2 is the typical value of DG credibility, λ c，2 is the capacity confidence level;

[0113] The capacity confidence λ c，2 The expression is

[0114]

[0115] In the above formula, S opt is the substation capacity obtained by solving the substation capacity probability planning model, S opt,0 is the substation capacity calculated using the probability planning method when the DG output is zero, S opt,1 It is the substation capacity calculated by the probabilistic planning method when only the maximum DG typical output curve state is adopted.

[0116] The total capacity requirement S of public substation under load power balance bz The expression is:

[0117] S bz =(K r -σ c，2 δ dg K g ) zx，fmax ;

[0118] The power supply balances the total capacity demand of the public substation S bz The expression is:

[0119] S bz =(σ c，2 K g -δ fh K r ) gmax ;

[0120] In the above formula, K r is the load operation factor, K g is the power generation operation coefficient, σ c，2 is the typical value of DG credibility.

[0121] The planning module is used to calculate the total capacity demand of public substations through the typical value of DG credibility, so as to obtain the substation planning scheme, which includes the total capacity demand of public substations, the optimal number of main transformers and the substation capacity; the specific method is as follows:

[0122] The total capacity demand of public substations is calculated by the typical value of DG credibility, and the substation planning scheme is obtained by combining the total capacity demand of public substations with the optimal number of main transformers and the substation capacity corresponding to the minimum cost.

[0123] The total capacity requirement S of public substation under load power balance bz The expression is:

[0124] S bz =(Kr -σ c，2 δ dg K g ) zx，fmax ;

[0125] The power supply balances the total capacity demand of the public substation S bz The expression is:

[0126] S bz =(σ c，2 K g -δ fh K r ) gmax ;

[0127] In the above formula, K r is the load operation factor, K g is the power generation operation coefficient, σ c，2 is the typical value of DG credibility.

[0128] A distribution network optimization dispatching device for interconnecting multiple distribution substations, wherein the substation planning for accessing high-penetration distributed power sources includes a processor and a memory;

[0129] The memory is used to store computer program code and transmit the computer program code to the processor;

[0130] The processor is used to execute the aforementioned substation planning method for accessing high-penetration distributed power sources according to the instructions in the computer program code.

[0131] Compared with the prior art, the present invention has the following beneficial effects:

[0132] 1. In a substation planning method for accessing high-penetration distributed power sources of the present invention, a substation capacity probability planning model is constructed based on the annual investment cost of the substation related to the capacity and the load power outage / DG power abandonment loss cost caused by the main transformer outage, and then the investment cost of all the number combinations within their capacity range is calculated by a simple enumeration method, thereby obtaining the total cost of each main transformer number combination. After comparison, the combination of the number of substations and the capacity with the minimum objective function can be obtained, thereby obtaining the optimal number of main transformers and the substation capacity corresponding to the minimum cost. Therefore, this design can quickly solve the substation capacity probability planning model through a simple enumeration method, obtain the optimal number of main transformers and the substation capacity corresponding to the minimum cost, and effectively improve the efficiency of substation planning.

[0133] 2. In a substation planning method for accessing high-permeability distributed power sources of the present invention, the load and output data in the planning area are calculated to obtain the DG permeability, DG critical permeability, load permeability and load critical permeability. By comparing the DG permeability, DG critical permeability, load permeability and load critical permeability, the calculation mode of the DG credibility typical value is determined to avoid the problem that the DG credibility typical value cannot be solved due to the huge or even infinite value of the power balance DG permeability. Therefore, this design can effectively improve the feasibility of the substation planning method by determining the DG credibility typical value calculation mode.

[0134] 3. In a substation planning method for accessing high-penetration distributed power sources of the present invention, the DG capacity credibility is obtained by the substation capacity corresponding to the optimal number of main transformers and the minimum cost. The DG credibility is the ratio of the capacity to be used by the DG in the power balance of the substation capacity planning to its maximum output. The total capacity demand of the public substation can be obtained by the ratio of the capacity to be used in the power balance to its maximum output. Therefore, this design can obtain the total capacity demand of the public substation through the DG capacity credibility, effectively improving the comprehensiveness of the substation planning method. BRIEF DESCRIPTION OF THE DRAWINGS

[0135] Figure 1 It is a flow chart of the present invention.

[0136] Figure 2 It is the overall flow chart of the algorithm of the present invention.

[0137] Figure 3 It is a schematic diagram of the photovoltaic output curve in Example 3.

[0138] Figure 4 This is a schematic diagram of a typical daily load curve in Example 3.

[0139] Figure 5 This is a schematic diagram of DG credibility under load power balance in the "PV-commercial" case in Example 3.

[0140] Figure 6 It is a schematic diagram of DG credibility under power balance in the "photovoltaic-commercial" case in Example 4.

[0141] Figure 7 The structure diagram of the system of the present invention is shown in FIG.

[0142] Figure 8 It is a structural diagram of the device described in the present invention. DETAILED DESCRIPTION

[0143] The present invention is further described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0144] Embodiment 1:

[0145] See also Figure 1 , a substation planning method for accessing high-penetration distributed power sources, the substation capacity planning method comprising:

[0146] S1, set the substation capacity as a variable, take the annual cost of substation investment related to the capacity and the total cost consisting of load power outage / DG power abandonment loss cost caused by the main transformer outage as the objective function, and construct a probabilistic planning model for substation capacity. The expression of the probabilistic planning model for substation capacity is:

[0147]

[0148] In the above formula, F Z is the total cost, F T is the annual cost of substation investment, F Q is the DG power abandonment fee, F K is the power outage loss cost, S Z is the total capacity of a single substation, n Z The number of main transformers, S d is the capacity of a single main transformer, ψ is the allowable DG power abandonment rate under normal conditions, P L，k is the comprehensive load size of the planning area in the kth period, P G，i，k is the output value of the i-th DG output state combination in the k-th period, X h is the number of time periods, X s The number of new energy output state combinations;

[0149] S2, solves the substation capacity probability planning model constructed in S1 to obtain the optimal number of main transformers and substation capacity;

[0150] S3, calculate the DG permeability, DG critical permeability, load permeability and load critical permeability through the load and output data in the planning area, select the DG credibility typical value calculation mode by comparing the DG permeability, DG critical permeability, load permeability and load critical permeability, and calculate the DG credibility typical value based on the selected calculation mode and the model solution result;

[0151] S4, the total capacity demand of public substation is calculated by the typical value of DG credibility, so as to obtain a substation planning scheme, wherein the substation planning scheme includes the total capacity demand of public substation, the optimal number of main transformers and the substation capacity.

[0152] In S1, the annual cost of substation investment F T The corresponding formula is obtained by linearly fitting the annual investment cost of substations with different capacities, and its expression is:

[0153] FT =ε(a+bS z );

[0154] In the above formula, ε=α+β+γ, wherein α is the maintenance rate, β is the return on investment, γ is the depreciation rate, a is a coefficient that is independent of capacity, and b is a coefficient that is related to capacity.

[0155] In S1, the power outage loss fee F K The expression is:

[0156] F K =F K，1 +F K，2 ;

[0157] In the above formula, F K，1 F is the power outage loss cost in the first stage, K，2 Cost of power outage losses during Phase 2;

[0158] The first stage power outage loss cost F K，1 And the second stage power outage loss cost F K，2 The expression is:

[0159]

[0160]

[0161] In the above formula, r b1 is the short-term power outage time of the main transformer, λ s，t is the planned maintenance rate of the main transformer, r s，t The planned outage time of the main transformer, Ω e is the set of single fault components that cause a single main transformer to lose power, λ f，e Ω e The failure rate of the e-th component in f，e is the fault outage time of the e-th component, c s The cost of planned power outages, c f The cost of power outage due to fault, P ki，1 is the power shortage power in the first stage of the i-th DG output state in time period k, P ki，2 is the power shortage power in the second stage of the i-th DG output state in time period k;

[0162] The power shortage power P of the first stage of the i-th DG output state in the k-th time period ki，1 And the power shortage power P in the second stage ki，2 The expression is:

[0163]

[0164]

[0165] In the above formula, is the power factor of the power flowing through the substation, P i is the probability of the i-th DG output state, α zj It is the correction factor for the impact of inter-station load transfer on the strain power station DG. When the inter-station load transfer of the substation has no impact on the strain power station, α zj =0, when the load transfer between substations has the same impact on the DG of the substation and the local station α zj =1, K zg，1 is the safe load rate of stage l, K zg，2 is the safe load factor for stage 2;

[0166] The safe load factor K of the first stage zg，1 And the second stage safety load factor K zg，2 The expression is:

[0167]

[0168] In the above formula, n z is the number of main transformers, K zn K is the maximum main transformer load rate that can be transferred within the station when there is no DG. zj It is the maximum main transformer load rate that can be transferred between stations when there is no DG.

[0169] In S1, the DG power abandonment fee F Q The expression is:

[0170] F Q =F Q，1 +F Q，2 ;

[0171] In the above formula, F Q，1 is the DG power curtailment cost in the first stage, F Q，2 It is the cost of DG power abandonment in the second stage;

[0172] The first stage DG power curtailment cost F Q，1 and the second stage DG power curtailment fee F Q，2 The expression is:

[0173]

[0174]

[0175] In the above formula, C C Penalty fee for DG power abandonment.

[0176] The S2 comprises the following steps:

[0177] S2.1, divide the substation power supply area into N a Part, determine the maximum load P of the substation power supply area 1max ;

[0178] S2.2, divide 24 hours a day into X h The corresponding daily load curve and P 1max Calculate the load P of the substation supply area in the kth period L，k ;

[0179] S2.3, calculate the output value P of the i-th DG output state combination in the k-th period G，i，k and its probability p i ;

[0180] S2.4, determine the combination of the number of substations and their capacity range, and select the substation capacity to meet the formula |P in the substation capacity probability planning model L，k -(1-ψ)P G，i，k |≤S z The minimum capacity is taken as the initial value, and incremented by the set step size ΔS to obtain the total capacity S of a single substation under different combinations of units. z ;

[0181] The calculation process is shown in Table 1.1:

[0182] Table 1.1 Construction scale of substations in different types of regions

[0183] Power supply area type Number of units / unit Single unit capacity / MVA A+, Class A 3～4 63、50 Category B 2～3 63、50、40 Category C 2～3 50、40、31.5 Category D 2～3 40、31.5、20 Category E 1～2 20、12.5、6.3

[0184] S2.5, calculate the investment cost F of all combinations of units within their capacity range T ;

[0185] S2.6, based on the load P of the substation supply area in the kth period L，k , the output value P of the i-th DG output state combination in the k-th period G，i，k , probability p i and capacity range, calculate the main transformer outage loss cost F for all combined capacity ranges K and DG power abandonment loss cost F Q ;

[0186] S2.7, calculate the F corresponding to each combination of main transformer numbers T 、F K and F Q Substitute it into the substation capacity probability planning model, calculate and compare the total cost of each combination of main transformer numbers, and select the one that makes the objective function F Z The combination of the minimum number of substations and the capacity, thus obtaining the optimal number of main transformers n z and the total capacity of the substation Sz , then output the optimal number of main transformers n z and the optimal substation total capacity S z As substation capacity S opt .

[0187] In S3, the DG permeability δ dg and DG critical permeability δ dg，c The expression is:

[0188]

[0189] The load permeability δ fh And the critical load permeability δ when the output of new energy remains constant fh，c The expression is:

[0190]

[0191] In the above formula, P zx，fmax P is the comprehensive grid load corresponding to the maximum forward power of the transformer equipment in the planning area. gmax is the maximum output of random renewable energy in the planning area, P fm is the maximum reverse power, P zm is the maximum forward power, and the maximum reverse power P fm Equal to the maximum forward power P zm The DG permeability is defined as the DG critical permeability δ when the grid supply comprehensive load remains unchanged dg，c ;

[0192] The maximum reverse power P fm And the maximum forward power P zm The expression is:

[0193]

[0194] In the above formula, P L，k is the comprehensive load size of the planning area in the kth period, P G，i，k is the output value of the i-th DG output state combination in the k-th period;

[0195] The judgment basis of the DG credibility typical value calculation mode is as follows: when the DG penetration rate is lower than the DG critical penetration rate or the load penetration rate is greater than the load critical penetration rate, the load power balance mode is used to calculate the DG credibility typical value; when the DG penetration rate is higher than the DG critical penetration rate or the load penetration rate is less than the load critical penetration rate, the power supply power balance mode should be used to calculate the DG credibility typical value;

[0196] In the load power balancing mode, calculation and analysis of typical values ​​of DG credibility are carried out based on one of different load densities or maximum loads and different DG penetration conditions;

[0197] In the power balance mode, the calculation and analysis of the typical value of DG credibility is carried out based on different power density or one of the maximum DG outputs and different load penetration conditions.

[0198] The expression of the typical value formula of DG credibility in S3 is:

[0199]

[0200] In the above formula, σ c，2 is the typical value of DG credibility, λ c，2 is the capacity confidence level;

[0201] The capacity confidence λ c，2 The expression is

[0202]

[0203] In the above formula, S opt is the substation capacity obtained by solving the substation capacity probability planning model, S opt,0 is the substation capacity calculated using the probability planning method when the DG output is zero, S opt,1 It is the substation capacity calculated by the probabilistic planning method when only the maximum DG typical output curve state is adopted.

[0204] In S4, the total capacity requirement of public substation under load power balance S bz The expression is:

[0205] S bz =(K r -σ c，2 δ dg K g ) zx，fmax ;

[0206] The power supply balances the total capacity demand of the public substation S bz The expression is:

[0207] S bz =(σ c，2 K g -δ fh K r ) gmax ;

[0208] In the above formula, K r is the load operation factor, K g is the power generation operation coefficient, σ c，2is the typical value of DG credibility.

[0209] The substation planning scheme obtained in S4 is shown in Table 1.2

[0210] Table 1.2 110kV distribution network transformer capacity load / power balance table taking into account DG (practical method)

[0211]

[0212] Note: "Load power balance" and "Source power balance" are used in scenarios where the maximum forward power of the device is greater than the maximum reverse power and the maximum reverse power is greater than the maximum forward power, respectively.

[0213] Embodiment 2:

[0214] See also Figure 7 , a substation planning system for accessing high-penetration distributed power sources, the substation planning system for accessing high-penetration distributed power sources comprising:

[0215] The model building module is used to take the substation capacity as a variable, and to minimize the total cost consisting of the annual substation investment cost related to the capacity and the load power outage / DG power abandonment loss cost caused by the main transformer outage as the objective function to build a substation capacity probability planning model. The expression of the substation capacity probability planning model is:

[0216]

[0217] In the above formula, F Z is the total cost, F T is the annual cost of substation investment, F Q is the DG power abandonment fee, F K is the power outage loss cost, S Z is the total capacity of a single substation, n Z The number of main transformers, S d is the capacity of a single main transformer, ψ is the allowable DG power abandonment rate under normal conditions, P L，k is the comprehensive load size of the planning area in the kth period, P G，i，k is the output value of the i-th DG output state combination in the k-th period, X h is the number of time periods, X s The number of new energy output state combinations;

[0218] The model solving module is used to solve the substation capacity probability planning model constructed by the model building module, so as to obtain the optimal number of main transformers and substation capacity;

[0219] A calculation mode judgment module is used to calculate the typical value of DG credibility through the model solution results, calculate the DG permeability, DG critical permeability, load permeability and load critical permeability through the load and output data in the planning area, select the calculation mode of DG credibility typical value by comparing the DG permeability, DG critical permeability, load permeability and load critical permeability, and calculate the DG credibility typical value based on the selected calculation mode;

[0220] The DG credibility typical value calculation module is used to calculate the DG permeability, DG critical permeability, load permeability and load critical permeability through the load and output data in the planning area, select the DG credibility typical value calculation mode by comparing the DG permeability, DG critical permeability, load permeability and load critical permeability, and calculate the DG credibility typical value based on the selected calculation mode and the model solution result;

[0221] The planning module is used to calculate the total capacity demand of public substations through the typical value of DG credibility, so as to obtain a substation planning scheme, which includes the total capacity demand of public substations, the optimal number of main transformers and the substation capacity.

[0222] Embodiment 3:

[0223] In order to verify the effectiveness of the present invention, a simulation study is conducted on a typical system through a substation planning method for accessing a high-penetration distributed power source according to the present invention:

[0224] See also Figures 2 to 6 In the planned area, the 110kV substation is stepped down to 10kV to supply power to users. The photovoltaic output curve is as follows Figure 3 As shown, the maximum utilization hours are 1553h; the corresponding state probability is shown in Table 1.3; the load in the area is commercial load, and its typical daily load curve is as follows Figure 4 As shown;

[0225] Combined with relevant statistical data, the load density values ​​used in typical scenarios are determined to be 0.1, 1, 5, 10, 20 and 30 MW / km 2 , power density values ​​are 0.1, 1, 5 and 10 MW / km 2 ; Secondly, consider the transfer rate K between different stations zj , different DG types, different feeder types, different load characteristics and different DG penetration rates are used for scenario classification; among them, the planned outage cost has different values ​​under different load densities, namely 0-5, 5-10, 10-20 and 20-30MW / km 2 The rates are 0.5, 5, 10 and 20 yuan / (kW·h) respectively; the fault outage cost is twice the corresponding planned outage cost, and the DG power abandonment penalty cost is 2.5 yuan / (kW·h);

[0226] Table 1.3 DG daily output state probability

[0227] Status Number 1 2 3 4 5 6 7 8 9 10 Photovoltaic probability / % 0.59 9.97 20.53 7.33 9.68 15.84 8.80 12.32 12.32 2.64 ;

[0228] In the "PV-commercial" scenario where the power source is PV and the load is commercial, the DG critical penetration rate and the load critical penetration rate are 193% and 52% respectively. Referring to the DG capacity credibility calculation method proposed in the present invention, the second type of credibility in the "PV-commercial" scenario is taken as an example for calculation and analysis, as shown in Tables 1.4 and 1.5:

[0229] Table 1.4 Relationship between DG credibility and DG penetration rate / power supply radius in the case of “PV-commercial”

[0230]

[0231] Table 1.5 Relationship between DG credibility and load penetration / power receiving radius in the case of "PV-commercial"

[0232]

[0233] The calculation results show that when performing load power balancing, the DG credibility will decrease with the increase of DG penetration rate. There is a case where the DG credibility is 0. This is because when the load is small, the cost corresponding to the required capacity value is the smallest. At this time, the presence or absence of DG has no effect on it. When performing power balancing, the DG credibility is mostly increased with the increase of K under the same load penetration rate. zj It increases with the increase of the value, and first decreases and then increases with the increase of load penetration. This is because when photovoltaic power maintains the maximum output state, there will still be a moment when the output value is 0. When the load penetration rate is small, it is greatly affected by the grid power output with a decreasing trend. However, when the load penetration rate increases to a certain level, the impact of the load is more significant.

[0234] Embodiment 4:

[0235] A distribution network optimization and scheduling device for interconnecting multiple distribution station areas, wherein the substation planning for accessing high-penetration distributed power sources includes a processor and a memory; the memory is used to store computer program code and transmit the computer program code to the processor; the processor is used to execute the substation planning method for accessing high-penetration distributed power sources described in Example 1 according to the instructions in the computer program code.

[0236] The above description is only a preferred embodiment of the present invention, and the protection scope of the present invention is not limited to the above embodiment. Any equivalent modifications or changes made by ordinary technicians in this field based on the contents disclosed by the present invention should be included in the protection scope recorded in the claims.

Claims

1. A method for planning a substation connected to a high-penetration distributed power source, characterized in that: The substation capacity planning method comprises: S1, set the substation capacity as a variable, take the annual cost of substation investment related to the capacity and the total cost consisting of load power outage / DG power abandonment loss cost caused by the main transformer outage as the objective function, and construct a probabilistic planning model for substation capacity. The expression of the probabilistic planning model for substation capacity is: In the above formula, F Z is the total cost, F T is the annual cost of substation investment, F Q is the DG power abandonment fee, F K is the power outage loss cost, S Z is the total capacity of a single substation, n Z The number of main transformers, S d is the capacity of a single main transformer, ψ is the allowable DG power abandonment rate under normal conditions, P L，k is the comprehensive load size of the planning area in the kth period, P G，i，k is the output value of the i-th DG output state combination in the k-th period, X h is the number of time periods, Xs 为 The number of new energy output state combinations; S2, solves the substation capacity probability planning model constructed in S1 to obtain the optimal number of main transformers and substation capacity; S3, calculate the DG permeability, DG critical permeability, load permeability and load critical permeability through the load and output data in the planning area, select the DG credibility typical value calculation mode by comparing the DG permeability, DG critical permeability, load permeability and load critical permeability, and calculate the DG credibility typical value based on the selected calculation mode and the model solution result; S4, the total capacity demand of public substation is calculated by the typical value of DG credibility, so as to obtain a substation planning scheme, wherein the substation planning scheme includes the total capacity demand of public substation, the optimal number of main transformers and the substation capacity.

2. According to claim 1, a method for planning a substation connected to a high-penetration distributed power source is characterized in that: In S1, the annual cost of substation investment F T The corresponding formula is obtained by linearly fitting the annual investment cost of substations with different capacities, and its expression is: F T =ε(a+bS z ); In the above formula, ε=α+β+γ, wherein α is the maintenance rate, β is the return on investment, γ is the depreciation rate, a is a coefficient that is independent of capacity, and b is a coefficient that is related to capacity.

3. According to a method for planning a substation connected to a high-penetration distributed power source according to claim 1, it is characterized in that: In S1, the power outage loss fee F K The expression is: F K =F K，1 +F K，2 ; In the above formula, F K，1 F is the power outage loss cost in the first stage, K，2 Cost of power outage losses during Phase 2; The first stage power outage loss cost F K，1 And the second stage power outage loss cost F K，2 The expression is: In the above formula, r b1 is the short-term power outage time of the main transformer, λ s，t is the planned maintenance rate of the main transformer, r s，t is the planned outage time of the main transformer, Ω e is the set of single fault components that cause a single main transformer to lose power, λ f，e Ω e The failure rate of the e-th component in f，e is the fault outage time of the e-th component, c s The cost of planned power outages, c f The cost of power outage due to fault, P ki， 1 is the power shortage power in the first stage of the i-th DG output state in time period k, P ki，2 is the power shortage power in the second stage of the i-th DG output state in time period k; The power shortage power P of the first stage of the i-th DG output state in the k-th time period ki，1 And the power shortage power P in the second stage ki，2 The expression is: In the above formula, is the power factor of the power flowing through the substation, P i is the probability of the i-th DG output state, α zj It is the correction factor for the impact of inter-station load transfer on the strain power station DG. When the inter-station load transfer of the substation has no impact on the strain power station, α zj =0, when the load transfer between substations has the same impact on the DG of the substation and the local station α zj =1, K zg，1 is the safety load factor of the first stage, K zg，2 is the safe load factor for stage 2; The safe load factor K of the first stage zg，1 And the second stage safety load factor K zg，2 The expression is: In the above formula, n z is the number of main transformers, K zn K is the maximum main transformer load rate that can be transferred within the station when there is no DG. zj It is the maximum main transformer load rate that can be transferred between stations when there is no DG.

4. The method for planning a substation connected to a high-penetration distributed power source according to claim 1, characterized in that: In S1, the DG power abandonment fee F Q The expression is: F Q =F Q，1 +F Q，2 ; In the above formula, F Q，1 is the DG power curtailment cost in the first stage, F Q，2 It is the cost of DG power abandonment in the second stage; The first stage DG power curtailment fee F Q，1 and the second stage DG power curtailment fee F Q，2 The expression is: In the above formula, C C Penalty fee for DG power abandonment.

5. The method for planning a substation connected to a high-penetration distributed power source according to claim 1, characterized in that: The S2 comprises the following steps: S2.1, divide the substation power supply area into N a Part, determine the maximum load P1 of the substation power supply area max ; S2.2, divide 24 hours a day into X h The corresponding daily load curve and P 1max Calculate the load P of the substation supply area in the kth period L，k ; S2.3, calculate the output value P of the i-th DG output state combination in the k-th period Gik and its probability pi; S2.4, determine the combination of the number of substations and their capacity range, and select the substation capacity to meet the formula |P in the substation capacity probability planning model L，k -(1-ψ)P G，i，k |≤S z The minimum capacity is taken as the initial value, and incremented by the set step size ΔS to obtain the total capacity S of a single substation under different combinations of units. z ; S2.5, calculate the investment cost F of all combinations of units within their capacity range T ; S2.6, based on the load P of the substation supply area in the kth period L，k , the output value P of the i-th DG output state combination in the k-th period Gi，k , probability pi and capacity range, calculate the main transformer outage loss cost F for all combined capacity ranges K and DG power abandonment loss cost F Q ; S2.7, calculate the F corresponding to each combination of main transformer numbers T 、F K and F Q Substitute it into the substation capacity probability planning model, calculate and compare the total cost of each combination of main transformer numbers, and select the one that makes the objective function F Z The combination of the minimum number of substations and the capacity, thus obtaining the optimal number of main transformers n z and the total capacity of the substation S z , then output the optimal number of main transformers n z and the optimal substation total capacity S z As substation capacity S opt .

6. A method for planning a substation connected to a high-penetration distributed power source according to claim 5, characterized in that: In S3, the DG permeability δ dg and DG critical permeability δ dg，c The expression is: The load permeability δ fh And the critical load permeability δ when the output of new energy remains constant fh，c The expression is: In the above formula, P zx，fmax P is the comprehensive grid load corresponding to the maximum forward power of the transformer equipment in the planning area. gmax is the maximum output of random renewable energy in the planning area, P fm is the maximum reverse power, P zm is the maximum forward power, and the maximum reverse power P fm Equal to the maximum forward power P zm The DG permeability is defined as the DG critical permeability δ when the grid supply comprehensive load remains unchanged dg，c ; The maximum reverse power P fm And the maximum forward power P zm The expression is: In the above formula, P L，k is the comprehensive load size of the planning area in the kth period, P G，i，k is the output value of the i-th DG output state combination in the k-th period; The judgment basis of the DG credibility typical value calculation mode is as follows: when the DG penetration rate is lower than the DG critical penetration rate or the load penetration rate is greater than the load critical penetration rate, the load power balance mode is used to calculate the DG credibility typical value; when the DG penetration rate is higher than the DG critical penetration rate or the load penetration rate is less than the load critical penetration rate, the power supply power balance mode should be used to calculate the DG credibility typical value; In the load power balancing mode, calculation and analysis of typical values ​​of DG credibility are carried out based on one of different load densities or maximum loads and different DG penetration conditions; In the power balance mode, the calculation and analysis of the typical value of DG credibility is carried out based on different power density or one of the maximum DG outputs and different load penetration conditions.

7. A method for planning a substation connected to a high-penetration distributed power source according to claim 6, characterized in that: The expression of the typical value formula of DG credibility in S3 is: In the above formula, σ c，2 is the typical value of DG credibility, λ c，2 is the capacity confidence level; The capacity confidence λ c，2 The expression is In the above formula, S opt is the substation capacity obtained by solving the substation capacity probability planning model, S opt,0 is the substation capacity calculated using the probability planning method when the DG output is zero, S opt,1 It is the substation capacity calculated by the probabilistic planning method when only the maximum DG typical output curve state is adopted.

8. The method for planning a substation connected to a high-penetration distributed power source according to claim 7, characterized in that: In S4, the total capacity requirement of public substation under load power balance S bz The expression is: S bz =(K r -s c，2 d dg K g )P zx，fmax ; The power supply balances the total capacity demand of the public substation S bz The expression is: S bz =(s c，2 K g -d fh K r )P gmax ; In the above formula, K r is the load operation factor, K g is the power generation operation coefficient, σ c，2 is the typical value of DG credibility.

9. A substation planning system for accessing high-penetration distributed power sources, characterized in that: The substation planning system for accessing high-penetration distributed power sources includes: The model building module is used to take the substation capacity as a variable, and to minimize the total cost consisting of the annual substation investment cost related to the capacity and the load power outage / DG power abandonment loss cost caused by the main transformer outage as the objective function to build a substation capacity probability planning model. The expression of the substation capacity probability planning model is: In the above formula, F Z is the total cost, F T is the annual cost of substation investment, F Q is the DG power abandonment fee, F K is the power outage loss cost, S Z is the total capacity of a single substation, n Z The number of main transformers, S d is the capacity of a single main transformer, ψ is the allowable DG power abandonment rate under normal conditions, P L，k is the comprehensive load size of the planning area in the kth period, P G，i，k is the output value of the i-th DG output state combination in the k-th period, X h is the number of time periods, X s The number of new energy output state combinations; The model solving module is used to solve the substation capacity probability planning model constructed by the model building module, so as to obtain the optimal number of main transformers and substation capacity; The DG credibility typical value calculation module is used to calculate the DG permeability, DG critical permeability, load permeability and load critical permeability through the load and output data in the planning area, select the DG credibility typical value calculation mode by comparing the DG permeability, DG critical permeability, load permeability and load critical permeability, and calculate the DG credibility typical value based on the selected calculation mode and the model solution result; The planning module is used to calculate the total capacity demand of public substations through the typical value of DG credibility, so as to obtain a substation planning scheme, which includes the total capacity demand of public substations, the optimal number of main transformers and the substation capacity.

10. A distribution network optimization dispatching device for interconnecting multiple distribution substations, characterized in that: The substation planning for accessing high-penetration distributed power sources includes a processor and a memory; The memory is used to store computer program code and transmit the computer program code to the processor; The processor is used to execute the substation planning method for accessing high-penetration distributed power sources as described in any one of claims 1 to 8 according to the instructions in the computer program code.

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