Unified optimal configuration method of intelligent switch equipment considering comprehensive cost

Abstract

The invention discloses an intelligent switch equipment unified optimization configuration method considering comprehensive cost, and the method comprises the steps: combining an emergency load control system network structure, and analyzing the load shedding execution conditions of an upper-layer dispatching automation system taking a circuit breaker as a main body and a lower-layer power distribution automation system taking a section switch as a main body after a system fault; based on the switch hierarchy of the emergency load control system and the combination effect between different switch devices, constructing a relation constraint; evaluating the optimal configuration comprehensive cost of the intelligent switch equipment; and comprehensively considering the installation cost of the switch equipment and the comprehensive cost of load shedding of the switch equipment, constructing an objective function of the intelligent switch equipment optimal configuration model, taking the relation constraint and the safety and stability constraint as constraint conditions of the intelligent switch equipment optimal configuration model, and solving the objective function under the constraint conditions to obtain a power distribution network switch configuration strategy. The method fully considers the load shedding balance, can be widely applied to power distribution system equipment, and has good expandability.

Description

Technical Field

[0001] The present invention relates to the technical field of power systems, and in particular to a unified optimization configuration method for intelligent switch equipment taking comprehensive costs into account. Background Art

[0002] In order to maximize resource utilization and minimize economic impact, the call value should be measured in combination with the characteristics of industrial loads and the corresponding economic benefits, so that industrial loads and their own accompanying call value can be uniformly included in the resource pool corresponding to the second-level / second-level demand. From the perspective of users or load agents participating in demand response, users can reasonably evaluate the economic effects of actively participating in emergency load demand; from the perspective of power grid dispatch, the construction of second-level demand response is the data support for the dispatch center to formulate scientific and reasonable dispatch plans, and provides a basis for giving full play to the role of demand response in emergency situations. Existing methods cannot effectively measure the call value of interruptible loads in the second-level demand response resource pool, and cannot formulate safer and more economical interruptible load installation and dispatch plans suitable for multiple scenarios. Summary of the invention

[0003] In view of this, the present invention provides a unified optimization configuration method for intelligent switching equipment taking into account comprehensive costs, aiming to provide an interruptible load resource pool construction strategy suitable for multiple scenarios under the premise of taking into account the constraints of intelligent switches, so as to solve the over-cutting problem caused by only considering calling the direct-controlled switches in the scheduling automation system in the existing strategy.

[0004] The present invention discloses a unified optimization configuration method for intelligent switch equipment taking comprehensive costs into account, which comprises:

[0005] Step 1: Combined with the network structure of the emergency load control system, analyze the load shedding performed by the upper dispatching automation system with circuit breakers as the main body and the lower distribution automation system with section switches as the main body after the system failure;

[0006] Step 2: Construct relational constraints based on the switch hierarchy of the emergency load control system and the combined effects between different switchgears;

[0007] Step 3: Evaluate the comprehensive cost of optimizing the configuration of intelligent switchgear;

[0008] Step 4: Considering the installation cost of the switchgear and the comprehensive cost of the load shedding of the switchgear, the objective function of the intelligent switchgear optimization configuration model is constructed, and the switch configuration strategy of the distribution network is obtained by solving the objective function.

[0009] Furthermore, in the network structure of the emergency load control system, the switch equipment is divided into two layers: the dispatching automation system is the upper layer of the emergency load control system, and its components are the circuit breakers in the substation, which are used to achieve unified control of all industrial switches connected to the transformer; the distribution automation system is the lower layer of the emergency load control system, which is connected to the dispatching automation system through a common line, and its components are the section switches in the switchgear / distribution room.

[0010] Furthermore, the step 2 comprises:

[0011] In the switch level of the emergency load control system, the lower-level distribution automation system is equipped with a sectionalizing switch to cut off the connected industrial load. The premise of load cutting is that the switch equipment configured on the feeder is closed, and the cost of installing and operating the switch equipment needs to be included in the comprehensive cost. If the existing circuit breaker of the upper-level dispatching automation system is directly called, all loads connected to the substation will be cut off at the same time, which is consistent with the effect of all feeder sectionalizing switches configured on the lower-level distribution automation system.

[0012] A series of relational constraints between the installation of lower-level switchgear and the function of upper-level switches: When all feeders in the lower-level distribution automation system need to be configured with switchgear, the upper-level configured substation circuit breakers are directly called to perform load shedding without installing section switches on the lower-level switch feeders.

[0013] Furthermore, the following formula is an expression of a series of relational constraints between the installation of the lower switchgear and the action of the upper switch:

[0014] 0≤x i,j,t ≤Z i,j

[0015]

[0016] w i =y i

[0017] y i ≤x i,j,t

[0018] Where i = 1, 2...N, Z i,j is a "0-1" variable, used to indicate whether a switch needs to be installed at the jth switch installation position connected to node i; i is a "0-1" variable, used to indicate whether the switch in the upper-level dispatching automation system connected to node i is in operation; x i,j,t is a "0-1" variable, used to indicate whether the jth switch connected to node i is in action at time t; w i is the “0-1” indicator variable introduced to directly characterize the load shedding of the industrial load at the i-th node: if w iis 1, indicating that all industrial loads connected to the i-th node are shedding loads. i is 0, indicating that the i-th node is connected to the industrial load part to perform load shedding; M is a constant; m represents the number of segment switches configured for a single node i; and N represents the number of nodes.

[0019] Furthermore, the step 3 comprises:

[0020] Comprehensive cost evaluation requires the calculation of two-stage costs. The first stage is the preparation stage, including the installation of switchgear, and the second stage is the action stage, including the comprehensive cost of load shedding and the cost of imbalanced switchgear action. The comprehensive cost of load shedding is determined by the industrial increase cost per kilowatt-hour and the coordinated recovery cost of the industrial chain. Among them, the industrial added value per kilowatt-hour of each industrial category obtained from the economic part is normalized and then matched with the industrial load connected to the node to obtain the industrial growth loss caused by cutting the jth industrial load connected to the i-th node, which is defined as the industrial increase cost per kilowatt-hour, denoted as S i,j,t ; The recovery order of the industrial chain of each industrial category obtained from the economic part is normalized, and then matched with the industrial load connected to the node to obtain the industrial chain recovery caused by cutting the jth industrial load connected to the ith node, which is defined as the collaborative recovery cost of the industrial chain, denoted as R i,j,t .

[0021] Furthermore, the comprehensive cost of load shedding determined by the added cost of the electricity industry and the cost of coordinated recovery of the industrial chain is recorded as d i,j,t , which is the comprehensive cost of load shedding for the jth industrial load connected to the i-th node at time t, and is expressed as:

[0022] d i,j,t =αS i,j,t +βR i,j,t

[0023] In the formula, α and β are the industrial value coefficient of electricity per kilowatt-hour and the coordinated recovery coefficient of the industrial chain, respectively. The two coefficients determine the proportion of the industrial increase cost of electricity per kilowatt-hour and the coordinated recovery cost of the industrial chain in the comprehensive cost of load shedding, and can be appropriately adjusted as external environmental factors change;

[0024] The degree of imbalance is defined as the minimum standard deviation of the load cut by each node when executing the second-level load demand response after the accident occurs, which is expressed as:

[0025]

[0026] Where u represents the unbalanced cost of the switching device operation, E i,t It represents the load removed by the switch device at the i-th node at time t, and n represents the number of nodes.

[0027] Furthermore, the switchgear installation cost is expressed as:

[0028] C A,i -w i M≤C i ≤C A,i +w i M

[0029] C B,i -(1-w i )M≤C i ≤C B,i +(1-w i )M

[0030]

[0031] C B,i =y i γ b

[0032] Among them, C i represents the cost of configuring the switch at node i; γ Z Installation operating costs for lower level sectionalizing switches; γ B is the upper circuit breaker operating cost; C i There are only two possible calculation methods, which are named A and B, and are expressed as: C A,i With C B,i ; The meaning of method A is that in the current scenario, only some of the industrial loads connected to the node i are cut off, and there is no need to call the substation circuit breaker. The switch equipment configuration cost of the node i needs to be calculated according to the actual number of configured switch equipment; the meaning of method B is that in the current scenario, all the industrial loads connected to the node i are cut off, and the existing substation circuit breaker can be directly called without configuring the feeder section switch.

[0033] Furthermore, the objective function of the intelligent switch device optimization configuration model is the comprehensive cost, which is expressed as:

[0034]

[0035] Furthermore, the safety and stability constraints of the intelligent switch device optimization configuration model include power flow balance constraints, branch power flow upper and lower limit constraints, node voltage upper and lower limit constraints, and generator power upper and lower limit constraints.

[0036] Furthermore, the expression of the power flow balance constraint is:

[0037]

[0038] Among them, E i,trepresents the load removed by the switch device at the i-th node at time t, that is, the sum of the loads of the switches connected to the i-th node performing load shedding operations at time t; P q,t represents the resident load at time t; P engin,t represents the total industrial load at time t; P G,t represents the generator power at time t;

[0039] The expressions of the upper and lower limit constraints of branch power flow are:

[0040] P L,t =E i,t ×PTDF

[0041]

[0042] Among them, P L,t is the power transferred by the line power caused by the node power change; PTDF is used to represent the power flow calculation distribution factor; P L,t Used to indicate line flow; P L,min , P L,max They represent the upper and lower limits of the line power flow respectively;

[0043] The expressions of node voltage upper and lower limit constraints are:

[0044]

[0045] Among them, U t represents the node voltage, U min , U max Respectively represent the upper and lower limits of the node voltage;

[0046] The expression of the upper and lower limit constraints of generator power is:

[0047]

[0048] in, Respectively represent the upper and lower limits of generator power.

[0049] Due to the adoption of the above technical solution, the present invention has the following advantages: the present invention fully utilizes the combined action relationship between devices, fully considers the load shedding balance, can be widely applied to power transmission and distribution system equipment, and has good scalability.

[0050] The present invention quantitatively analyzes the call value of interruptible loads: provides a basis for building a resource pool for response to second-level load demand; combines the evaluated economic benefits of second-level load demand response, establishes a second-level load resource pool that takes into account safety and economy in multiple scenarios, and combines the interruptible load resources in the resource pool to provide a scheduling plan for emergency situations. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the embodiments of the present invention. For ordinary technicians in this field, other drawings can also be obtained based on these drawings.

[0052] Figure 1 A schematic flow chart of a unified optimization configuration method for intelligent switch devices taking comprehensive costs into account according to an embodiment of the present invention;

[0053] Figure 2 A schematic diagram of the network structure of an emergency load control system according to an embodiment of the present invention;

[0054] Figure 3 A schematic diagram of the switch level of an embodiment of the present invention;

[0055] Figure 4 The actual industrial load distribution diagram of a power grid in a certain region according to an embodiment of the present invention;

[0056] FIG5( a ) is a schematic diagram of switch configurations for scenarios one, two, and three of an embodiment of the present invention;

[0057] FIG5( b ) is a schematic diagram of switch configuration in scenario 4 of an embodiment of the present invention;

[0058] Figure 6 A schematic diagram of a switch configuration strategy adapted to multiple scenarios according to an embodiment of the present invention. DETAILED DESCRIPTION

[0059] The present invention is further described in conjunction with the accompanying drawings and embodiments, and the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by ordinary technicians in this field should fall within the scope of protection of the embodiments of the present invention.

[0060] See also Figure 1 The present invention provides an embodiment of a unified optimization configuration method for intelligent switch devices taking comprehensive costs into account, which includes:

[0061] S1: Combined with the network structure of the emergency load control system, the upper dispatching automation system with circuit breakers as the main body and the lower distribution automation system with section switches as the main body are analyzed to perform load shedding after system failure;

[0062] In one embodiment, combined with the structure of the emergency load control system, the upper dispatching automation system with circuit breakers as the main body and the lower distribution automation system with section switches as the main body are analyzed to perform load shedding after a system failure. Figure 2, the following key information can be obtained according to the network structure of the emergency load control system:

[0063] ① The switchgear in the emergency load control system is divided into two layers: the dispatching automation system is the upper layer of the emergency load control system, and its components are the circuit breakers in the 10kV substation, which are used to realize the unified control of all industrial switches connected to the transformer; the distribution automation system is the lower layer of the emergency load control system, which is connected to the dispatching automation system through a public line, and its components are the section switches in the switchgear / distribution room; ② In reality, some transformer circuit breakers in the dispatching automation system are directly connected to the industrial load through a dedicated line, which is not considered in the present invention; ③ In the distribution automation system, there are some 10kV tap switches that directly connect the transformer and the industrial load through a public line, which is also not considered in the present invention; ④ In actual situations, the circuit breakers of the substation at the dispatching automation level have all been installed, so the switchgear at this level can be called, and when calculating the total cost of the switchgear configuration, this part of the installation cost can be ignored; ⑤ The present invention presets that the 10kV outgoing line switch in the substation is directly connected to the load node in all scenarios; ⑥ The present invention presets that a number of industrial loads are connected to a load node in all scenarios.

[0064] S2: Construct relational constraints based on the switch hierarchy of the emergency load control system and the combined effects between different switchgears;

[0065] In one embodiment, relationship constraints are constructed based on the switch hierarchy of the emergency load control system and the combined effects between different switch devices. The schematic diagram of the switch hierarchy of the emergency load control system is as follows: Figure 3 ,according to Figure 3 It can be found that: ① The configuration of sectionalizing switches in the lower-level distribution automation system can cut off the connected industrial loads. The premise of load cutting is that the switch equipment must be configured on the feeder, and the cost of installing and operating the switch equipment needs to be included in the comprehensive cost; ② If the existing circuit breaker of the upper-level dispatching automation system is directly called, all loads connected to the substation will be cut off at the same time, which is consistent with the effect of configuring sectionalizing switches on all feeders in the lower-level distribution automation system, thereby saving the cost of configuring switches. A series of relationship constraints between the installation of the lower-level switch equipment and the action of the upper-level switch are as follows:

[0066] 0≤x i,j,t ≤Z i,j

[0067]

[0068] w i =y i

[0069] y i ≤x i,j,t

[0070] Where i = 1, 2...N, Z i,j is a "0-1" variable, used to indicate whether a switch needs to be installed at the jth switch installation position connected to node i; i is a "0-1" variable, used to indicate whether the switch in the upper-level dispatching automation system connected to node i is in operation; x i,j,t is a "0-1" variable, used to indicate whether the jth switch connected to node i is in action at time t; w i is the “0-1” indicator variable introduced to directly characterize the load shedding of the industrial load at the i-th node: if w i is 1, indicating that all industrial loads connected to this node will be shelved. i =0, indicating that the node is connected to the industrial load part to perform load shedding; M represents a sufficiently large constant; m represents the number of segment switches configured for a single node i; N represents the number of nodes. The above formula shows that configuring segment switches is a prerequisite for performing load shedding, and also explains the combined action mechanism of the upper-level dispatching automation circuit breaker and its lower-level distribution automation system segment switches: In a certain scenario, the Z corresponding to the jth industrial load connected to the i-th node i,j When both are 1, the circuit breaker action variable corresponding to the node is 1. The meaning of the constraint in formula (1) is: when all feeders in the lower-level distribution automation system need to be configured with switch devices, the upper-level configured substation circuit breakers are directly called to perform load shedding, without installing section switches on the lower-level switch feeders.

[0071] S3: Evaluate the comprehensive cost of optimizing the configuration of intelligent switchgear;

[0072] In one embodiment, comprehensive cost assessment requires calculation of two-stage costs. The first stage is the preparation stage, including the installation of switchgear. The second stage is the action stage, including the comprehensive cost of load shedding (determined by the increased cost of the power industry and the cost of coordinated recovery of the industrial chain) and the cost of imbalanced operation of switchgear.

[0073] The relevant concepts for measuring comprehensive cost are explained as follows:

[0074] The electricity industry increases the cost of using S i,j,t Indicates that the industrial added value per kilowatt-hour of electricity is defined as the amount of industrial GDP contributed by 1 kilowatt-hour of electricity. In principle, the electricity load with small industrial added value but large volume should be limited first, and then the electricity load with large industrial added value but small volume should be limited. The industrial added value per kilowatt-hour of electricity of each industrial category obtained from the economic part is normalized, and then matched with the industrial load connected to the node to obtain the industrial growth loss caused by cutting the jth industrial load connected to the i-th node, which is defined as the industrial added cost per kilowatt-hour of electricity, recorded as S i,j,t .

[0075] The cost of coordinated recovery of the industrial chain is expressed in Ri,j,t It indicates that, combined with the distribution of the industrial chain, in order to maximize the synergistic benefits of the industrial economy, combined with the past experience of orderly power consumption, the power consumption of some "chain leader" enterprises in the industrial load that implements orderly power consumption has recovered relatively quickly. This shows that under abnormal circumstances, such industrial enterprises can restore production order quickly and the local supporting facilities are relatively complete, and the economic benefit loss of cutting such industrial loads is relatively small. Similarly, the recovery order of the industrial chain of each industrial category obtained from the economic part is normalized, and then matched with the industrial load connected to the node to obtain the recovery of the industrial chain caused by cutting the jth industrial load connected to the i-th node, which is defined as the cost of industrial chain synergy recovery, recorded as R i,j,t .

[0076] The comprehensive cost of load shedding determined by the added cost of the electricity industry and the coordinated recovery cost of the industrial chain is recorded as d i,j,t , which is the comprehensive cost of load shedding for the jth industrial load connected to the i-th node at time t, and can be expressed as:

[0077] d i,j,t =αS i,j,t +βR i,j,t (2)

[0078] Where α and β are the industrial value coefficient per kilowatt-hour and the coordinated recovery coefficient of the industrial chain, respectively. The two coefficients determine the proportion of the industrial increase cost per kilowatt-hour and the coordinated recovery cost of the industrial chain in the comprehensive cost of load shedding, and can be adjusted appropriately with changes in external environmental factors.

[0079] The cost of unbalanced switchgear action is represented by u. After the accident, try to make the nodes with centralized industrial loads bear relatively balanced responsibilities and make the load reduction amount roughly similar, that is, the standard deviation of the load cut by each node in executing the second-level load demand response takes the minimum value, and this indicator is defined as the imbalance degree, which is as follows:

[0080]

[0081] Where: u represents the unbalanced cost of the switching device operation, E i,t It represents the load removed by the switch device at the i-th node at time t, and n represents the number of nodes.

[0082] S4: Considering the installation cost of the switchgear and the comprehensive cost of the load shedding of the switchgear, the objective function of the intelligent switchgear optimization configuration model is constructed, and the switch configuration strategy of the distribution network is obtained by solving the objective function.

[0083] In one embodiment, the switchgear installation cost is expressed as follows by combining the above factors:

[0084] C A,i -w i M≤Ci ≤C A,i +w i M

[0085] C B,i -(1-w i )M≤C i ≤C B,i +(1-w i )M

[0086]

[0087] C B,i =y i γ B

[0088] Formula (4) is used to calculate the cost of configuring the switch at node i, using C i Represents; γ Z Installation operating cost for lower sectionalizing switch, γ B is the upper circuit breaker operating cost, because the switch here has been installed, so the value is 0; C i There are only two possible calculation methods, which are named A and B, and are expressed as: C A,i With C B,i ; The meaning of mode A is that in the current scenario, only some of the industrial loads connected to node i are cut off, and there is no need to call the substation circuit breaker. The configuration cost of the switch equipment of this node needs to be calculated according to the number of switch equipment actually configured; the meaning of mode B is that in the current scenario, all the industrial loads connected to node i are cut off, and the existing substation circuit breaker can be directly called without configuring the feeder section switch. Therefore, at this time, C i It is not difficult to find that the appropriate use of substation circuit breakers will significantly reduce the installation and operation costs of switchgear.

[0089] The purpose of optimizing the configuration of the emergency load control system switches is to minimize the comprehensive cost while meeting the system reliability requirements by determining the location, type and quantity of switchgear such as circuit breakers and section switches. Therefore, the objective function of the intelligent switchgear optimization configuration model established by the present invention is the comprehensive cost, as shown in formula (5):

[0090]

[0091] Based on the switch combination action constraints and objective function of the intelligent switch device optimization configuration model, other safety and stability constraints are considered to ensure the stable operation of the power system.

[0092] The newly added safety and stability constraints are as follows:

[0093] (1) Node load shedding:

[0094]

[0095] E i,t It represents the load removed by the switch device at the i-th node at time t, that is, the sum of the loads cut off by the switches connected to the i-th node at time t.

[0096] (2) Flow balance constraints:

[0097]

[0098] Among them, P q,t represents the resident load at time t; P engin,t represents the total industrial load at time t; P G,t represents the generator power at time t.

[0099] The power flow balance constraint equation stipulates that the amount of load reduction must be balanced with the generator power, other load powers and the load that has not performed demand response operations, which is used to characterize the basic reliability of the load emergency control system.

[0100] (3) Upper and lower limit constraints of branch flow:

[0101]

[0102] Among them, P L,t is the power transferred by the line power caused by the node power change; PTDF is used to represent the power flow calculation distribution factor; P L,t Used to indicate line flow; P L,min , P L,max Respectively represent the upper and lower limits of the line flow. Formula (8) is the upper and lower limit constraints of the branch flow;

[0103] (4) Node voltage upper and lower limit constraints:

[0104]

[0105] Among them, U t represents the node voltage, U min , U max Respectively represent the upper and lower limits of the node voltage.

[0106] (5) Generator power upper and lower limit constraints:

[0107]

[0108] in, Respectively represent the upper and lower limits of generator power.

[0109] The complete model of the unified optimization configuration of the intelligent switch device proposed in the present invention is as follows:

[0110] Objective function (5)

[0111] Constraints (1)-(4), (6)-(10)

[0112] For ease of understanding, the present invention provides a more specific embodiment:

[0113] (1) Test system

[0114] The present invention takes the actual 10kV distribution network in a certain area as an example to compare the effectiveness of the proposed method. Figure 4 As shown in the figure, generators with outputs of 180MW and 100MW are configured at nodes 6 and 8 respectively, variable loads are configured at nodes 2, 4 and 6, and fixed loads of 10MW are configured at the remaining nodes. The department nodes are connected to industrial loads. Assuming that each industrial load is 6.25MW, the distribution of industrial loads at the nodes is shown in Table 1. The parameters in the switchgear configuration model are set as follows: the installation and operation cost of the section switch is 1, the industrial value coefficient α is 0.3, the industry chain synergy recovery coefficient β is 0.7, and the industrial increase cost S is 0. i,j,t And the cost of coordinated recovery of the industrial chain R i,j,t See Table 2.

[0115] Table 1 The added cost of electricity industry in each industrial sector and the cost of coordinated recovery of the industrial chain

[0116]

[0117]

[0118] Table 2 Industrial load distribution of emergency load control system in the example

[0119]

[0120]

[0121]

[0122] Note: (i,j) represents the jth industrial load connected to the i-th node.

[0123] The purpose of configuring switchgear in the distribution network and building an emergency load control system is to effectively deal with the "source-load" imbalance in various emergency situations, which requires the analysis of various fault scenarios. First, four typical fault scenarios (including extreme scenarios) are analyzed, and then the fault scenarios are further expanded to obtain the switchgear configuration strategy of the emergency load control system that comprehensively considers different degrees of fault scenarios and measures the comprehensive cost of configuring and operating the switchgear under different degrees of fault conditions.

[0124] Four typical scenarios considered by the present invention are shown in Table 3:

[0125] Table 3 Typical scenarios

[0126] Scenario Emergency Situations Scenario I Generator output less than 25MW Scene II Load surge 50MW Scene III Generator output 50MW less Scene IV Generator output decreased by 75MW; load increased by 50MW

[0127] Among them, scenario IV is an extreme scenario.

[0128] Figure 5(a) and Figure 5(b) show the distribution network switch configuration strategies obtained by using the commercial solver Gurobi in four scenarios. Table 4 shows the switch equipment configuration, load shedding, switch load shedding imbalance cost, switch installation cost and comprehensive cost corresponding to the four scenarios.

[0129] Table 4 Switch configuration strategies for typical scenarios

[0130]

[0131] As mentioned above, in the typical scenario switch configuration strategy, the switch configuration strategies of scenario II and scenario III are the same, and the "source-load" unbalance deficit caused by their respective faults in the above two scenarios is the same; the "source-load" unbalance deficit in scenario I and scenario IV is different from that in other scenarios, and the corresponding switch configuration strategies are different. It can be seen that the difference between different scenarios is essentially the difference in the "source-load" unbalance deficit caused by faults.

[0132] When a fault occurs, configuring the switch first and then operating the switch obviously cannot solve the "source-load" imbalance in a very short time. Therefore, it is necessary to configure the switch equipment in advance. However, according to each typical scenario and switch configuration strategy, the switch equipment configuration strategy with the best comprehensive cost for different scenarios is different. Therefore, it is necessary to formulate a set of switch equipment configuration strategies suitable for multiple scenarios. When a sudden fault occurs, load shedding is performed according to the configured switch equipment and load shedding plan to ensure the normal operation of the power system. To formulate a switch equipment configuration strategy suitable for multiple scenarios, it is necessary to comprehensively consider the scenarios with different "source-load" imbalance and shortfall, so as to achieve the optimal overall comprehensive cost of the switch equipment configuration strategy in each scenario.

[0133] Consider the overall comprehensive cost in each scenario. The overall cost consideration standard is the average cost of each scenario and the comprehensive cost of extreme scenarios.

[0134] In order to implement the developed switchgear configuration strategy, it is necessary to extensively consider the comprehensive cost of configuring switchgear and performing load shedding operations under various fault conditions, that is, under different "source-load" unbalance shortages. Therefore, it is necessary to construct a wide number of scenarios with different "source-load" unbalance shortages. The switchgear configuration strategy derived based on a wide range of rich scenarios is more universally applicable.

[0135] The method proposed in the present invention comprehensively considers the average cost of each scenario and the comprehensive cost of extreme scenarios, calculates the switch configuration strategy applicable to multiple scenarios, and compares the average cost calculated with the switch configuration strategy with the lowest cost in extreme scenarios. Figure 6 The comprehensive cost of installing switches and executing load shedding under different “source-load” unbalanced shortage situations under this strategy is shown in Table 5.

[0136] Table 5 Switch configuration strategies applicable to multiple scenarios

[0137]

[0138]

[0139] In order to demonstrate the comprehensive cost advantage brought by the method proposed in the present invention of making full use of the functional characteristics and combined advantages of different equipment, the present invention will provide a solution that does not call the substation circuit breaker in the dispatching automation, and only installs the section switch in the distribution systematization system (hereinafter referred to as "Scheme 1"), and compares and analyzes the comprehensive cost of the switch equipment configuration strategy (hereinafter referred to as "Scheme 2") provided by the present invention.

[0140] Without calling the substation circuit breaker in the dispatching automation, in Scheme 1, in order to ensure the reliability of the power system distribution network, it is necessary to install sectionalizers on all feeders connected to industrial loads in the distribution automation system. Using the method proposed in the present invention that comprehensively considers the average cost of each scenario and the comprehensive cost of extreme scenarios, the comprehensive cost of executing load shedding in Scheme 1 under different scenarios of "source-load" imbalance shortage is calculated, and the obtained strategy is shown in Table 6.

[0141] Table 6 Comprehensive cost of plan 1

[0142]

[0143]

[0144] Compare Scheme 1 with Scheme 2, as shown in Table 7:

[0145] Table 7 Comparison of schemes

[0146]

[0147] The comparison of the indicators of the two schemes in Table 7 shows that: ① Compared with Scheme 1, Scheme 2 greatly reduces the switch installation cost; ② Compared with Scheme 1, the average cost of each scenario and the comprehensive cost of extreme scenarios in Scheme 2 are significantly reduced. It can be concluded that by studying and applying the combined action relationship between equipment, the comprehensive cost will be significantly reduced while ensuring the safety and stability of the power system.

[0148] The case analysis shows that the present invention can give full play to the functional characteristics and combined advantages of different switch devices, flexibly, economically and efficiently solve the "source-load" imbalance problem, fully improve the utilization efficiency of equipment, and effectively reduce the total system cost.

[0149] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the relevant field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents. Any modification or equivalent replacement that does not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A unified optimization configuration method for intelligent switchgear considering comprehensive cost, characterized in that: include: Step 1: Combined with the network structure of the emergency load control system, analyze the load shedding performed by the upper dispatching automation system with circuit breakers as the main body and the lower distribution automation system with section switches as the main body after the system failure; Step 2: Construct relational constraints based on the switch hierarchy of the emergency load control system and the combined effects between different switchgears; Step 3: Evaluate the comprehensive cost of optimizing the configuration of intelligent switchgear; Step 4: Considering the installation cost of switchgear and the comprehensive cost of load shedding of switchgear, the objective function of the intelligent switchgear optimization configuration model is constructed. The relationship constraints and safety and stability constraints are used as the constraints of the intelligent switchgear optimization configuration model. Under the constraints, the objective function is solved to obtain the distribution network switch configuration strategy.

2. The method according to claim 1, characterized in that: In the network structure of the emergency load control system, the switch equipment is divided into two layers: the dispatching automation system is the upper layer of the emergency load control system, and its components are the circuit breakers in the substation, which are used to achieve unified control of all industrial switches connected to the transformer; the distribution automation system is the lower layer of the emergency load control system, which is connected to the dispatching automation system through a common line, and its components are the section switches in the switchgear / distribution room.

3. The method according to claim 1, characterized in that The step 2 comprises: In the switch level of the emergency load control system, the lower-level distribution automation system is equipped with a sectionalizing switch to cut off the connected industrial load. The premise of load cutting is that the switch equipment configured on the feeder is closed, and the cost of installing and operating the switch equipment needs to be included in the comprehensive cost. If the existing circuit breaker of the upper-level dispatching automation system is directly called, all loads connected to the substation will be cut off at the same time, which is consistent with the effect of all feeder sectionalizing switches configured on the lower-level distribution automation system. A series of relational constraints between the installation of lower-level switchgear and the function of upper-level switches: When all feeders in the lower-level distribution automation system need to be configured with switchgear, the upper-level configured substation circuit breakers are directly called to perform load shedding without installing section switches on the lower-level switch feeders.

4. The method according to claim 3, characterized in that The following formula is an expression of a series of relationship constraints between the installation of the lower switchgear and the action of the upper switch: 0≤x i,j,t ≤Z i,j w i =y i and i ≤x i,j,t Where i = 1, 2...N, Z i,j is a "0-1" variable, used to indicate whether a switch needs to be installed at the j-th switch installation position connected to node i; i is a "0-1" variable, used to indicate whether the switch in the upper-level dispatching automation system connected to node i is in operation; x i,j,t is a "0-1" variable, used to indicate whether the jth switch connected to node i is in action at time t; w i is the "0-1" indicator variable introduced to directly characterize the load shedding situation of the industrial load at the i-th node: if w i is 1, indicating that all industrial loads connected to the i-th node are shedding loads. i is 0, indicating that the i-th node is connected to the industrial load part to perform load shedding; M is a constant; m represents the number of segment switches configured for a single node i; and N represents the number of nodes.

5. The method according to claim 1, characterized in that The step 3 comprises: Comprehensive cost evaluation requires the calculation of two-stage costs. The first stage is the preparation stage, including the installation of switchgear, and the second stage is the action stage, including the comprehensive cost of load shedding and the cost of imbalanced switchgear action. The comprehensive cost of load shedding is determined by the industrial increase cost per kilowatt-hour and the coordinated recovery cost of the industrial chain. Among them, the industrial added value per kilowatt-hour of each industrial category obtained from the economic part is normalized and then matched with the industrial load connected to the node to obtain the industrial growth loss caused by cutting the jth industrial load connected to the i-th node, which is defined as the industrial increase cost per kilowatt-hour, denoted as S i,j,t ; The recovery order of the industrial chain of each industrial category obtained from the economic part is normalized, and then matched with the industrial load connected to the node to obtain the industrial chain recovery caused by cutting the jth industrial load connected to the i-th node, which is defined as the collaborative recovery cost of the industrial chain, denoted as R i,j,t .

6. The method according to claim 5, characterized in that The comprehensive cost of load shedding determined by the added cost of the electricity industry and the cost of coordinated recovery of the industrial chain is recorded as d i,j,t , which is the comprehensive cost of load shedding for the jth industrial load connected to the i-th node at time t, and is expressed as: d i,j,t =αS i,j,t +βR i,j,t In the formula, α and β are the industrial value coefficient of electricity per kilowatt-hour and the coordinated recovery coefficient of the industrial chain, respectively. The two coefficients determine the proportion of the industrial increase cost of electricity per kilowatt-hour and the coordinated recovery cost of the industrial chain in the comprehensive cost of load shedding, and can be appropriately adjusted as external environmental factors change; The degree of imbalance is defined as the minimum standard deviation of the load cut by each node when executing the second-level load demand response after the accident occurs, which is expressed as: Where u represents the unbalanced cost of the switching device operation, E i,t It represents the load removed by the switch device at the i-th node at time t, and n represents the number of nodes.

7. The method according to claim 1, characterized in that The switchgear installation cost is expressed as: C A,i -w i M≤C i ≤C A,i +w i M C B,i -(1-w i )M≤C i ≤C B,i +(1-w i )M C B,i =y i c B Among them, C i represents the cost of configuring the switch at node i; γ Z Installation operating costs for lower level sectionalizing switches; γ B is the upper circuit breaker operating cost; C i There are only two possible calculation methods, which are named A and B, and are expressed as: C A,i With C B,i ; The meaning of method A is that in the current scenario, only some of the industrial loads connected to the node i are cut off, and there is no need to call the substation circuit breaker. The switch equipment configuration cost of the node i needs to be calculated according to the actual number of configured switch equipment; the meaning of method B is that in the current scenario, all the industrial loads connected to the node i are cut off, and the existing substation circuit breaker can be directly called without configuring the feeder section switch.

8. The method according to claim 6, characterized in that The objective function of the intelligent switch device optimization configuration model is the comprehensive cost, which is expressed as: Where: e i,j,t Represents the power value of the jth switch connected to node i at time t.

9. The method according to claim 1, characterized in that: The safety and stability constraints of the intelligent switch device optimization configuration model include power flow balance constraints, branch power flow upper and lower limit constraints, node voltage upper and lower limit constraints, and generator power upper and lower limit constraints.

10. The method according to claim 9, characterized in that The expression of the power flow balance constraint is: Among them, E i,t represents the load removed by the switch device at the i-th node at time t, that is, the sum of the loads of the switches connected to the i-th node performing load shedding operations at time t; P q,t represents the resident load at time t; P engin,t represents the total industrial load at time t; P G,t represents the generator power at time t; The expressions of the upper and lower limit constraints of branch power flow are: P L,t =And i,t ×PDF Among them, P L,t is the power transferred by the line power caused by the node power change; PTDF is used to represent the power flow calculation distribution factor; P L,t Used to indicate line flow; P L,min , P L,max They represent the upper and lower limits of the line power flow respectively; The expressions of node voltage upper and lower limit constraints are: Among them, U t represents the node voltage, U min , U max Respectively represent the upper and lower limits of the node voltage; The expression of the upper and lower limit constraints of generator power is: in, Respectively represent the upper and lower limits of generator power.

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