Current protection operation boundary calculation method based on new energy aggregation and protection constraint

Abstract

The invention discloses a current protection operation boundary calculation method based on new energy aggregation and protection constraint, and the method comprises the steps: taking a single feeder line divided by a feeder connected with the same bus of a transformer substation as a segmented line; executing a step-by-step rotation checking process: calculating the new energy admission capacity of the current segmented line under the reverse non-maloperation constraint of the current protection section III at the current protection part of the current segmented line, and calculating the new energy admission capacity of the current segmented line; and the maximum total capacity of the new energy allowed to be accessed to all the feeder lines on the transformer substation is obtained and serves as the applicable boundary of current protection. Compared with the prior art, the rapid calculation method for the current protection applicable boundary of the power grid with high proportion of new energy and multi-point access is realized, and the calculation efficiency of the calculation method is remarkably improved.

Description

Technical Field

[0001] The present invention relates to the field of relay protection of new energy power systems, and in particular to a method for quickly calculating the operating boundary of current protection of a power grid under high-proportion new energy access. Background Art

[0002] The new power system will gradually shift from being dominated by synchronous power sources to being dominated by new energy sources. Among them, the high proportion of new energy access has become one of the main characteristics of the distribution network. The traditional distribution network is generally a single-power radial power supply network, which usually only needs to be configured with non-directional current protection. Under the high proportion of new energy access, the power grid changes from a single-power radial network to a complex network with multiple active terminals, which leads to a decrease in the sensitivity of non-directional current protection and even false operation. The existing current protection applicable boundary assessment method has a core problem of low computational efficiency in power grids with a high proportion of new energy and multi-point access. However, after a high proportion of new energy is connected to the distribution network, the magnitude and direction of the fault current will change, resulting in a decrease in the sensitivity of the original current protection and even false operation. The multi-point access of a high proportion of new energy makes the fault current of the distribution network flow in both directions, and it is difficult for traditional current protection to meet the action selectivity requirements. The applicable boundary of the current protection of the distribution network under the high proportion of new energy access has received widespread attention. Chinese invention patent 202311375500.9 "Method for evaluating the applicable boundary of current protection in the distribution network under distributed photovoltaic access" takes into account the requirements of current protection selectivity and reliability, and proposes a method for calculating the operating boundary of distribution network current protection with photovoltaic access capacity as the boundary. However, in actual projects, there are multiple new energy sources connected between each two protections, and the specific location of the access is unknown. The above-mentioned existing current protection applicable boundary evaluation method has a core problem of low calculation efficiency in the distribution network with a high proportion of new energy and multiple points of access. Therefore, it is urgent to propose a new method that can significantly improve the calculation efficiency of the operating boundary of distribution network current protection. Summary of the invention

[0003] For distribution networks with a high proportion of renewable energy access, the present invention proposes a current protection operating boundary calculation method based on renewable energy aggregation and protection constraints. On the basis of renewable energy aggregation, a step-by-step rotation verification design of protection constraints is performed, thereby realizing a fast calculation method for the current protection operating boundary of the distribution network.

[0004] In a first aspect, the present invention provides a method for calculating a current protection operation boundary based on new energy aggregation and protection constraints, comprising:

[0005] The feeders connected to the same busbar of the substation are split into single feeder lines as segmented lines;

[0006] The step-by-step round-robin verification process further includes:

[0007] (i) Calculate the maximum access capacity of new energy sources on the segmented lines from the first segmented line to the second to last segmented line under the sensitivity constraint of the current protection section II;

[0008] (ii) Calculate the maximum value of the sum of the new energy capacity on the first segmented line and the second to last segmented line under the remote backup sensitivity constraint of the current protection III section from the first segmented line to the second to last segmented line;

[0009] (iii) Calculate the maximum allowed capacity of new energy on the segmented line under the constraint that the reverse current protection at the end of the current feeder will not malfunction;

[0010] (iv) The current segmented line is set as the second-to-last segmented line, and a judgment is made based on the access capacity of the downstream segmented circuit of the current segmented line and the access capacity of the current protection section III on the current segmented line: if the upper limit of the access capacity of the downstream segmented circuit of the current segmented line is greater than the upper limit of the access capacity of the current protection section III on the current segmented line and the current segmented line is the first segmented line, the maximum total capacity of the new energy allowed to be connected to the feeder is taken as the applicable boundary of the current protection on the feeder, and the maximum total capacity of the new energy allowed to be connected to all feeders on the substation is obtained; otherwise, the access capacity of the new energy on the current segmented line is calculated under the constraint that the current protection section III at the current protection of the current segmented line does not malfunction in the reverse direction;

[0011] (v) The new energy connected to the current segment line and its downstream segment exceeds the current line current protection section III remote backup sensitivity constraint, calculate the new energy access capacity of the current segment line;

[0012] (vi) Until the maximum total capacity of renewable energy allowed to be connected to all feeders of the substation is obtained as the applicable boundary of current protection.

[0013] The (i) further includes placing the new energy connected to the upstream segment line from the first segment line to the current segment line in an out-of-operation state, and placing the new energy on the downstream segment line from the current segment line to the last segment circuit in a shielding state.

[0014] The above (ii) further includes aggregating the current segmented route and its downstream segmented route to the exit position of the current segmented route, placing the new energy connected from the first segmented route to the downstream segmented route of the current segmented route in an exit operation state, and placing the new energy on the next-level segmented route from the downstream segmented route of the current segmented route to the last segmented route in a shielded state.

[0015] In (iv), the new energy capacity connected to the downstream segment circuit e+1 of the current segment line has reached the upper limit of access under the sensitivity constraint of the upper-level current protection section III remote backup.

[0016] In (iv), the new energy access capacity S of the current segmented line l_e =min{S l_e B ,S l_e Ⅱ}, where S l_e B It represents the new energy access capacity on the current segment line under the constraint that the current protection III section of the current protection of the current segment line will not be misoperated in the reverse direction, S l_e Ⅱ It represents the maximum value of the new energy access capacity of the line under the sensitivity constraint of the sectional line current protection section II.

[0017] In (v), the new energy access capacity S of the current segment line l_e =S l_e Ⅲ -S l_e+1 , S l_e Ⅲ Indicates the upper limit of the current protection capacity of the current segment III on the current segment line, S l_e+1 Indicates the new energy capacity connected to the upstream segment line of the current segment line.

[0018] In (iv), the applicable boundary of the current protection on feeder l is the maximum total capacity of new energy sources allowed to be connected to feeder l, which is S l =S l_1 +S l_2 +…+S l_n , S l_1 +S l_2 +…+S l_n It represents the new energy capacity connected to the 1, 2, ...n segments of feeder l.

[0019] In (v), the maximum total capacity of renewable energy that can be connected to all feeders on the substation is S max =S1+S2+…+S m , S1+S2+…+S m It represents the renewable energy capacity connected to the 1st, 2nd, ..., mth feeders in the substation.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] 1) The feeders connected to the same busbar of the substation are split into single feeder lines as segmented lines, and a step-by-step rotation verification is performed based on the aggregation of new energy sources, which realizes a fast calculation method for the applicable boundary of current protection of power grids with high proportion of new energy and multi-point access, and significantly improves the calculation efficiency of the calculation method;

[0022] 2) Provide a calculation method for the current protection operating boundaries of power grids with a high proportion of new energy and multi-point access, greatly improving the calculation speed. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a typical two-feeder distribution system structure diagram.

[0024] Figure 2 This is the overall flow chart of the current protection operation boundary calculation method based on new energy aggregation and protection constraints. DETAILED DESCRIPTION

[0025] The technical solution proposed by the present invention is described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0026] like Figure 1 As shown in the figure, a typical two-feeder distribution system (the connected new energy source is photovoltaic) is taken as an example, where CB 1-1 CB 1-2 CB 1-3 Represents the circuit breaker corresponding to each line, i.e., feeder 1, CB 2-1 CB 2-2 ,...,CB 2-n Represents the circuit breakers corresponding to each line, i.e., feeder 2, which are all equipped with three-stage current protection, where current protection section I refers to current quick-break protection, current protection section II refers to time-limited current quick-break protection, and current protection section III specifies time-limited overcurrent protection, and n represents the number of segmented lines on feeder 2. Since in the actual distribution network, multiple new energy sources may be connected between each two current protections, and the specific location of the new energy access is unknown, the new energy sources, i.e., photovoltaics, between each two current protections can be aggregated in one location when calculating the protection operation boundary. The principle of aggregation is to aggregate the new energy sources between each two current protections at the location that has the most serious impact on the current protection performance conditions. The current protection performance constraints are divided into three levels: reverse non-false operation constraints, current protection sensitivity constraints of current protection section II, and remote backup sensitivity constraints of current protection section III. The sensitivity constraints of current protection section III are divided into near backup sensitivity constraints and remote backup sensitivity constraints. The three-level constraints are used to implement verification in a step-by-step rotation manner.

[0027] Take feeder 2 as an example, CB 2_n The current protection reverse non-false tripping constraint is only for new energy PV 1 2_n ~PV p 2_n The capacity of new energy PV 1 2_n ~PV p 2_nThe closer the photovoltaic access location is to the current protection, the smaller the line impedance between the current protection and the renewable energy source, and the greater the short-circuit current flowing through the current protection. Therefore, the renewable energy source close to the head end of the line has a greater impact on the reverse misoperation of the current protection. 1 2_n ~PV p 2_n Aggregate to PV 1 2_n , the final calculated PV 1 2_n Admission capacity, as PV 1 2_n ~PV p 2_n The maximum total capacity of the feeder, p represents the number of renewable energy sources between each two current protections. Similarly, the renewable energy sources of each line segment should be aggregated to a position close to the head end of the line, and different feeders are calculated in the order of first calculating the capacity constraints of the downstream renewable energy sources imposed by the current protection at the end of the feeder, and then calculating upstream step by step.

[0028] The method of the present invention uses the total access capacity of new energy as the operating boundary indicator of current protection. For the access capacity of new energy under the reverse non-false operation constraint, different feeders are split and calculated separately. The reverse non-false operation constraint is that the maximum reverse fault current flowing through the protection is less than the set value of the current protection stage III.

[0029] The access of new energy will affect the sensitivity constraint of current protection section II, so the sensitivity constraint of current protection section II is the maximum capacity allowed for the access of new energy. The sensitivity constraint of current protection section II requires that the sensitivity coefficient after a short-circuit fault occurs at the end of this line is greater than 1.3. The sensitivity constraint of current protection section II is checked based on the minimum short-circuit current flowing through the current protection when a two-phase short-circuit fault occurs at the end of this line. At this time, other feeders and new energy sources upstream of the current protection should be shut down. This line is the line where the current protection is located. In addition, the new energy sources downstream of the line where the current protection is located are isolated by the fault point, and the impact on the sensitivity constraint of current section II can be ignored. Therefore, in order to simplify aggregation, the sensitivity constraint of current section II is only related to the new energy of this line, and the closer the new energy access location is to the current protection, the more obvious its auxiliary effect is, and the greater the impact on the sensitivity constraint of current protection section II. Taking the above factors into consideration, when calculating the sensitivity constraint of current protection section II, the new energy of each segmented line should also be aggregated to a position close to the head end of the line, and the sensitivity constraint of current protection section II on each segmented line only limits the capacity of the new energy connected to this line. Therefore, different feeders are calculated in the order of first calculating the capacity constraint of the feeder head end protection on the new energy in its segment, and then calculating downstream step by step.

[0030] Since the set value of the current section III protection is less than the set value of the current section II protection, under the sensitivity constraint of the current protection section II, the sensitivity constraint of the current protection section III is greater than 1.3 after a fault occurs at the end of this line, and the sensitivity constraint of the current protection section III near backup must meet the requirements and does not need to be verified. The sensitivity of the current protection section III far backup is verified based on the minimum short-circuit current flowing through the current protection under the two-phase short-circuit fault at the end of the next-level segmented line. After a fault occurs at the end of the next-level line, the sensitivity constraint of the current protection section III is greater than 1.2. At this time, the boosting effect of the new energy between the current protection and the fault point will cause the short-circuit current flowing through the protection to decrease. The closer the new energy access position is to the protection, the greater the impact on the sensitivity of the current protection section III, and the more obvious its boosting effect. Therefore, when calculating the maximum access capacity of new energy under the far backup sensitivity constraint of the current protection section III, the new energy of this segmented line and the next-level segmented line should be aggregated to a position close to the head end of this line, and the calculated new energy access capacity is the maximum value of the sum of the access capacities of this line and the next-level line.

[0031] like Figure 2 As shown, the specific process of the current protection operation boundary calculation method based on new energy aggregation and protection constraints of the present invention is as follows:

[0032] Step 1: The number of feeders connected to a substation bus is m, and the current feeder index l=1. Different feeders under the same bus are split into single feeder lines as segmented lines. The number of segmented lines on the feeder is recorded as n, and the segmented line index is recorded as e. The new energy on each segmented line is aggregated to the segmented line exit;

[0033] Step 2, perform the following operations on any feeder: When calculating the maximum capacity of new energy connected to the current segment line e under the sensitivity constraint of current section II, the new energy connected from the first segment line to the downstream segment lines 1 to e-1 of the current line will be shut down, and the new energy from the downstream segment line of the current segment line to the last segment circuit e+1~n will be shielded. Since the feeder end line is not equipped with current section II, 1≤e≤n-1. The particle swarm algorithm-based protection applicable boundary calculation method proposed in the invention patent "Method for evaluating the applicable boundary of current protection in the distribution network under distributed photovoltaic access" is used to calculate the maximum access capacity of new energy on the segment lines under the sensitivity constraint of current protection section II from the first segment line to the penultimate segment line 1~n-1, which is recorded as S l_1 Ⅱ ~S l_n-1 Ⅱ ;

[0034] Specifically, the boundary assessment method applicable to the current protection of the distribution network direction under distributed photovoltaic access includes the following steps:

[0035] Step 2.1, initialize the particle swarm information. Specifically, the particle swarm information includes the number of particles in the particle swarm PsoSize, the particle dimension (i.e., the number of distributed photovoltaics connected to the distribution network PsoDim), and the maximum number of iterations of the algorithm K max and the photovoltaic capacity combination x and photovoltaic capacity change combination v of each particle;

[0036] Step 2.2: Calculate the iteratively updated photovoltaic capacity combination x of particle j j and the photovoltaic capacity change combination v j , as shown below:

[0037]

[0038] In the formula, k represents the current number of iterations, K max represents the maximum number of iterations, j represents the number of particles, ω represents the inertia weight, ω max and ω min Represent their maximum and minimum values ​​respectively, c1 and c2 represent normal numbers that measure the importance of self-cognition factors and social influence factors respectively, r1 and r2 represent random numbers uniformly distributed in the region [0,1], and They represent the position of the photovoltaic capacity combination of particle j at the current iteration number k and the change speed of the photovoltaic capacity combination, Pbest j represents the optimal photovoltaic capacity combination currently found by particle j, and Gbest represents the optimal photovoltaic capacity combination found by all particles so far;

[0039] Step 2.3, check whether the photovoltaic capacity combination of particle j meets the constraint condition 1 of current protection sensitivity. Constraint condition 1 is shown as follows:

[0040]

[0041] In the formula, and They represent the threshold values ​​of stage I, stage II and stage III of line i current protection based on the current protection setting principle, respectively. It represents the fault current flowing through line i when the PV upstream of line i and other feeders are out of operation and a two-phase short circuit fault occurs 15% away from the head end of line i. It represents the fault current flowing through line i when the PV upstream of line i and other feeders are out of operation and a two-phase short circuit fault occurs at the end of line i. It represents the fault current flowing through line i when the PV upstream of line i and other feeders are out of operation and a two-phase short circuit fault occurs at the end of the next line of line i. n and m represent the number of lines in the distribution network and the number of lines other than the end line of each feeder, respectively.

[0042] If constraint condition 1 is satisfied, then execute step 4; if constraint condition 1 is not satisfied, then execute step 7;

[0043] Step 2.4, check whether particle j meets the constraint condition 2 of the direction criterion that the reverse fault does not cause false operation. The constraint condition 2 is as follows:

[0044]

[0045] Where l represents the total number of lines equipped with directional current protection in the distribution network, K d.i Indicates the voltage range of the photovoltaic grid connection point allowed under the condition that the reverse fault does not cause false operation of line i, K r.i Indicates the actual grid-connected voltage range of the downstream photovoltaic when a fault occurs in the reverse misoperation area of ​​the overcurrent judgment of line i, k umin.i , k umax.i Respectively represent the minimum and maximum values ​​of the range, where k umin.i is the voltage of the downstream photovoltaic when a three-phase short circuit fault occurs near the back end of line i, k umax.i is the fault location p of the distribution network max_bound The voltage of the downstream PV at ;

[0046] If constraint condition 2 is satisfied, execute step 5; if constraint condition 2 is not satisfied, execute step 7;

[0047] Step 2.5, check whether particle j meets the constraint condition 3 of the direction criterion that the positive fault does not refuse to move. The constraint condition 3 is as follows:

[0048] k u.i (α)∈K' d.i. (α)i=1,2...c;α∈(0,1]

[0049] In the formula, c represents the number of lines with photovoltaic terminals, α represents the ratio of the fault distance of the positive adjacent line to the total length of the line, and k u.i (α) represents the PV voltage at the end of line i when a fault occurs at the adjacent line α, K' d.i. (α) represents the voltage range of the photovoltaic grid connection point allowed under the condition that the directional criterion of line i does not cause false tripping due to a forward fault;

[0050] If constraint condition 3 is satisfied, then execute step 6; if constraint condition 3 is not satisfied, then execute step 7;

[0051] Step 2.6, update the individual optimum and global optimum of the photovoltaic capacity combination. The process specifically includes the following operations:

[0052] First, calculate the fitness of the current particle j, as shown in the following formula:

[0053] fitness=S PV_1 +S PV_2 +…+S PV_PSODim

[0054] In the formula, S PV_1 , S PV_2 ,...,S PV_PSODim Indicates the capacity of photovoltaic PV_1, PV_2, and PV_PsoDim;

[0055] Then, compare the fitness value of particle j with the fitness value of its current optimal position. When the fitness value is larger, update the individual optimal combination Pbestj of particle j; compare the fitness value of particle j with the fitness value of the global optimal position of the particle swarm. When the fitness value is larger, update the global optimal combination Gbest of the particle swarm.

[0056] Step 2.7, check whether all particles have completed the update, specifically whether the number of particles j that have completed the test reaches the total number of particles PsoSize in the particle group. If so, execute step 8; if not, set j=j+1, and then return to step 2;

[0057] Step 2.8: Check whether the number of iterations k has reached the maximum number of iterations K max : If it is reached, the current optimal photovoltaic capacity combination Gbest is obtained, where the sum of all photovoltaic capacities is the maximum access capacity of photovoltaics, that is, the applicable boundary of current protection; if it is not reached, set k=k+1 and j=1, and then return to step 2 to continue iteration;

[0058] Step 3, when calculating the maximum access capacity of new energy sources for the current segment line e and the downstream segment line e+1 (1≤e≤n-1) under the current section III remote backup sensitivity constraint, aggregate the current segment line e and the downstream segment line e+1 to the exit of the current segment line e, and the new energy sources connected from the first segment line on the current feeder to the downstream segment lines 1 to e-1 of the current segment line should be shut down, while the new energy sources on the next-level segment line from the downstream segment line of the current segment line to the last segment line e+2 to n are negligible. Similarly, the particle swarm algorithm-based protection applicable boundary calculation method proposed in the invention "Method for evaluating the applicable boundary of current protection in the distribution network under distributed photovoltaic access" (i.e., steps 2.2 to 2.8) is used to calculate the maximum value of the sum of the new energy capacities of the first segment line and the second-to-last segment line under the current protection section III remote backup sensitivity constraint from the first segment line to the second-to-last segment line 1 to n-1, recorded as S l_1 Ⅲ ~S l_n-1 Ⅲ ;

[0059] Step 4: Calculate the current protection CB at the end of the feederl_n The maximum value of the new energy access capacity of the segmented line under the constraint of no false operation in the reverse direction S l_n B At this time, the maximum new energy access capacity S of the feeder end segment line n l_n =S l_n B ; First, let the current segmented line be the second to last segmented line e=n-1;

[0060] Step 5: If the upper limit of the capacity of the downstream segment circuit e+1 of the current segment line is greater than the upper limit of the capacity of the current protection segment III on the current segment line, that is, S l_e+1 >S l_e Ⅲ , then let S l_e+1 =S l_e Ⅲ , since the new energy capacity connected to the downstream segment circuit e+1 of the current segment line has reached the upper limit of access under the sensitivity constraint of the upper level current protection III section remote backup, the upper limit of the new energy access capacity of the current segment line e is S l_e =0, jump directly to step 8; if S l_e+1 ≤S l_e Ⅲ , then go to step 6;

[0061] Step 6: Connect the access capacity S of new energy to the downstream segment line e+1 of the current segment line l_e+1 Substitute and calculate the current segment line current protection CB l_e The new energy access capacity S on the current segment line e under the constraint of no false operation of the current protection section III in the reverse direction l_e B , at this time, the new energy access capacity S of the current segment line e l_e =min{S l_e B ,S l_e Ⅱ};

[0062] Step 7, if S l_e +S l_e+1 >S l_e Ⅲ , it means that the access to new energy on the current segment line e and the downstream segment e+1 exceeds the limit of the current protection III section remote backup sensitivity constraint of the current segment line e. Therefore, the new energy access capacity S of the current segment line e is set to l_e =S l_e Ⅲ -S l_e+1 Otherwise, the new energy access capacity S of the current segment line e l_e remain unchanged;

[0063] Step 8, determine whether the current segmented line is the first segmented line, that is, whether e is equal to 1: If not, that is, e is not equal to 1, then set the upstream segmented line as the current segmented line, that is, set e = e-1, and return to step 5; if e is equal to 1, then the applicable boundary of the current protection on feeder l, that is, the maximum total capacity of new energy allowed to be connected to feeder l is S l =S l_1 +S l_2 +…+S l_n , the feeder protection applicable boundary calculation is completed, and the process goes to step 9;

[0064] Step 9: Whether the calculation of protection applicable boundaries of all feeders has been completed: Determine whether l is equal to m: If not, set l = l + 1 and return to step 1; If equal, it is completed, and the maximum total capacity S of new energy allowed to be connected to all feeders on the substation is obtained. max =S1+S2+…+S m .

[0065] The above 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 shall be included in the protection scope of the present invention. The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications made without departing from the principle of the present invention should also be regarded as falling within the protection scope of the present invention.

Claims

1. A method for calculating the operating boundary of current protection based on new energy aggregation and protection constraints, characterized in that: include: The feeders connected to the same busbar of the substation are split into single feeder lines as segmented lines; The step-by-step round-robin verification process further includes: (i) Calculate the maximum access capacity of new energy sources on the segmented lines from the first segmented line to the second to last segmented line under the sensitivity constraint of the current protection section II; (ii) Calculate the maximum value of the sum of the new energy capacity on the first segmented line and the second to last segmented line under the remote backup sensitivity constraint of the current protection III section from the first segmented line to the second to last segmented line; (iii) Calculate the maximum allowed capacity of new energy on the segmented line under the constraint that the reverse current protection at the end of the current feeder will not malfunction; (iv) The current segmented line is set as the second-to-last segmented line, and a judgment is made based on the access capacity of the downstream segmented circuit of the current segmented line and the access capacity of the current protection section III on the current segmented line: if the upper limit of the access capacity of the downstream segmented circuit of the current segmented line is greater than the upper limit of the access capacity of the current protection section III on the current segmented line and the current segmented line is the first segmented line, the maximum total capacity of the new energy allowed to be connected to the feeder is taken as the applicable boundary of the current protection on the feeder, and the maximum total capacity of the new energy allowed to be connected to all feeders on the substation is obtained; otherwise, the access capacity of the new energy on the current segmented line is calculated under the constraint that the current protection section III at the current protection of the current segmented line does not malfunction in the reverse direction; (v) The new energy connected to the current segment line and its downstream segment exceeds the current line current protection section III remote backup sensitivity constraint, calculate the new energy access capacity of the current segment line; (vi) Until the maximum total capacity of renewable energy allowed to be connected to all feeders of the substation is obtained as the applicable boundary of current protection.

2. The current protection operation boundary calculation method based on new energy aggregation and protection constraints according to claim 1 is characterized in that: The (i) further includes placing the new energy connected to the upstream segment line from the first segment line to the current segment line in an out-of-operation state, and placing the new energy on the downstream segment line from the current segment line to the last segment circuit in a shielding state.

3. The current protection operation boundary calculation method based on new energy aggregation and protection constraints according to claim 1 is characterized in that: The above (ii) further includes aggregating the current segmented route and its downstream segmented route to the exit position of the current segmented route, placing the new energy connected from the first segmented route to the downstream segmented route of the current segmented route in an exit operation state, and placing the new energy on the next-level segmented route from the downstream segmented route of the current segmented route to the last segmented route in a shielded state.

4. The current protection operation boundary calculation method based on new energy aggregation and protection constraints according to claim 1 is characterized in that: In (iv), the new energy capacity connected to the downstream segment circuit e+1 of the current segment line has reached the upper limit of access under the sensitivity constraint of the upper-level current protection section III remote backup.

5. The current protection operation boundary calculation method based on new energy aggregation and protection constraints according to claim 1 is characterized in that: In (iv), the new energy access capacity S of the current segmented line l_e =min{S l_e B ,S l_e Ⅱ }, where S l_e B It represents the new energy access capacity on the current segment line under the constraint that the current protection III section of the current protection of the current segment line will not be misoperated in the reverse direction, S l_e Ⅱ It represents the maximum value of the new energy access capacity of the line under the sensitivity constraint of the sectional line current protection section II.

6. The current protection operation boundary calculation method based on new energy aggregation and protection constraints according to claim 1 is characterized in that: In (v), the new energy access capacity S of the current segment line l_e =S l_e Ⅲ -S l_e+1 , S l_e Ⅲ Indicates the upper limit of the current protection capacity of the current segment III on the current segment line, S l_e+1 Indicates the new energy capacity connected to the upstream segment line of the current segment line.

7. The current protection operation boundary calculation method based on new energy aggregation and protection constraints according to claim 1 is characterized in that: In (iv), the applicable boundary of the current protection on feeder l is the maximum total capacity of new energy sources allowed to be connected to feeder l, which is S l =S l_1 +S l_2 +…+S l_n , S l_1 +S l_2 +…+S l_n It represents the new energy capacity connected to the 1, 2, ...n segments of feeder l.

8. The current protection operation boundary calculation method based on new energy aggregation and protection constraints according to claim 1 is characterized in that: In (v), the maximum total capacity of renewable energy that can be connected to all feeders on the substation is S max =S1+S2+…+S m , S1+S2+…+S m It represents the renewable energy capacity connected to the 1st, 2nd, ..., mth feeders in the substation.

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