Multi-time-scale multi-resource collaborative scheduling method for low-voltage interconnected distribution areas

Abstract

The present invention provides a multi-timescale, multi-resource collaborative scheduling method for low-voltage interconnected distribution substations, comprising the following steps: S1, constructing a low-voltage interconnected distribution substation architecture and a loss model for key equipment; S2, constructing a multi-timescale, multi-resource collaborative scheduling model for low-voltage interconnected distribution substations with the objectives of optimizing system operation economy, three-phase imbalance, and overall voltage deviation; S3, collecting long- and short-timescale distribution network source-load data; S4, inputting the long-timescale distribution network source-load data into the collaborative scheduling model to obtain OLTC and CB action schemes; S5, inputting the short-timescale distribution network source-load data and OLTC and CB action schemes into the collaborative scheduling model to obtain F-SOP and commutator action schemes; and S6, integrating the OLTC, CB, F-SOP, and commutator action schemes to obtain the multi-timescale, multi-resource collaborative scheduling result.

Description

Technical Field

[0001] This invention relates to the field of power grid technology, and in particular to a multi-time-scale, multi-resource collaborative scheduling method for low-voltage interconnected distribution areas. Background Technology

[0002] With the rapid development of the social economy and new power systems, the penetration rate of distributed energy and stochastic loads in distribution networks continues to increase, leading to a significant increase in the complexity of power flow control in distribution networks. Low-voltage distribution substations at the 380V level are characterized by strong network topology heterogeneity, diverse load types, and random, time-varying access of single and three-phase loads. This easily leads to typical problems such as abnormal transformer load rates, exceeding three-phase imbalance limits, and increased line loss rates, posing a severe challenge to the safe, stable operation and economic optimization of low-voltage distribution substations.

[0003] Currently, in addressing the issues of light and heavy loads and three-phase imbalance in low-voltage distribution transformer areas, some scholars utilize mechanical equipment such as capacitor banks (CB) and on-load tap changers (OLTC) to macroscopically control these problems, or employ four-leg soft openpoints (F-SOPs) to manage three-phase imbalances and achieve power balance. Commutators can address three-phase imbalances on the line side of the distribution area, thus reducing line losses. However, existing control methods often target only a single problem and cannot achieve comprehensive multi-objective management of interconnected distribution areas. Furthermore, due to the differences in source-load uncertainty fluctuations at different time scales, and the differences in response speeds between traditional mechanical equipment, F-SOPs, and commutators, establishing a multi-time-scale collaborative optimization strategy for these resources is a pressing challenge. Summary of the Invention

[0004] To address the limitations of traditional control methods in simultaneously resolving three-phase imbalance in distribution transformer areas, OLTC light and heavy loads, and excessive network losses, this invention provides a multi-timescale, multi-resource collaborative scheduling method for low-voltage interconnected transformer areas.

[0005] To solve the above-mentioned technical problems, the present invention adopts the following technical method: a multi-time-scale, multi-resource collaborative scheduling method for low-voltage interconnection areas, comprising:

[0006] Step S1: Construct a low-voltage interconnected distribution substation architecture, including multiple adjustable resources such as CB, OLTC, F-SOP, and commutator, as well as a loss model for key equipment.

[0007] Step S2: Construct a multi-timescale, multi-resource collaborative scheduling model for low-voltage interconnected distribution areas with the objectives of optimal system operation economy, optimal three-phase imbalance, and optimal overall voltage deviation. The solution process of this model is divided into a long-timescale optimization stage and a short-timescale optimization stage. In the long-timescale optimization stage, the model is constrained by the characteristics of key system equipment and the power flow security of system operation. In the short-timescale optimization stage, the model is constrained by the characteristics of key system equipment, the power flow security of system operation, and the long-short-timescale adjustment amount.

[0008] Step S3: Collect power distribution network source and load data on both long and short time scales;

[0009] Step S4: Input the long-time scale distribution network source-load data into the multi-time scale multi-resource collaborative scheduling model, solve the long-time scale optimization stage results, and obtain the OLTC and CB action schemes;

[0010] Step S5: Input the short-timescale distribution network source-load data and the obtained OLTC and CB action schemes into the multi-timescale multi-resource collaborative scheduling model, solve the short-timescale optimization stage results, and obtain the F-SOP and commutator action schemes.

[0011] Step S6: Integrate the OLTC and CB action schemes and the F-SOP and commutator action schemes to obtain the multi-timescale multi-resource collaborative scheduling results for low-voltage interconnected distribution areas.

[0012] Furthermore, in the short-timescale optimization stage, a multi-scenario stochastic programming method is adopted to consider the uncertainty of the load of each phase in order to predict the active and reactive loads of each phase.

[0013] Furthermore, the constraints of the long-term optimization phase include three-phase four-wire network operation constraints, F-SOP operation constraints, commutator operation constraints, OLTC operation constraints, CB operation constraints, and power balance constraints.

[0014] Furthermore, the constraints of the short-timescale optimization stage include three-phase four-wire network operation constraints, F-SOP operation constraints, commutator operation constraints, power balance constraints, and long-to-short-timescale adjustment constraints.

[0015] Furthermore, the long-short timescale adjustment constraint is a constraint on the F-SOP and the commutator's short-short timescale operating state change based on the long-time scale operating state, as shown in the following formula:

[0016] (1)

[0017] In the formula: , These are F-SOP access nodes for long and short time scales, respectively. VSC in e Active power transmitted in phase, e Phase refers to phase a, b, or c; For F-SOP access nodes VSC in e The maximum operable active power for long-term, short-timescale transmission; , These are F-SOP access nodes for long and short time scales, respectively. VSC in e The reactive power transmitted in phase; For F-SOP access nodes VSC in e The maximum operable reactive power quantity for long-term, short-time-scale transmission; , They are respectively the long and short time scales. The scalar value representing the operating status of the phase commutator; For the first The maximum operable quantity of the commutator.

[0018] Furthermore, the operating constraints of the three-phase four-wire network include power flow constraints, which are expressed as follows:

[0019] (2)

[0020] In the formula: , They represent Active power and reactive power injected into each phase of the node; , They are respectively Active power and reactive power of the branch circuit; , They are respectively Active power and reactive power of the branch circuit; , They are respectively , Nodes e Phase voltage; Indicates the flow of electricity to the node The set of all upstream nodes to which power is injected; , indicating from node The set of all downstream nodes to which the outflowing power reaches via the power grid; Indicates the reactance of each phase of the circuit; Indicates the resistance of each phase of the circuit; Represented as e Mutually The current in the branch circuit; Indicates the conductance of each phase of the circuit; Indicates the susceptance of each phase of the circuit;

[0021] make Using the second-order cone relaxation method, the non-convex constraint in equation (2) is transformed into a convex constraint, and then solved linearly. The transformed power flow constraint is as follows:

[0022] (3).

[0023] Furthermore, the objective function of the multi-timescale, multi-resource collaborative scheduling model for low-voltage interconnected distribution areas is as follows:

[0024] (4)

[0025] In the formula: These are the weighting factors for the objectives of economy, three-phase imbalance, and overall voltage deviation, respectively. These are the measured overall operating cost of the system, three-phase imbalance, and overall voltage deviation, respectively. The weights for the targets of economy, three-phase imbalance, and overall voltage deviation are respectively. These are the initial values ​​of the economic efficiency, three-phase imbalance, and overall voltage deviation targets before optimization;

[0026] 1) Economic objectives of the distribution area:

[0027] (5)

[0028] In the formula: The overall operating cost of the system; The total operating cost of F-SOP includes F-SOP maintenance costs and depreciation costs; The total operating cost of the commutator includes the cost of commutator operation and loss. The total cost of OLTC includes depreciation costs and operating costs; Cost of CB action; Cost of loss in a three-phase four-wire network;

[0029] ①F-SOP Overall Operating Cost

[0030] (6)

[0031] In the formula: , These represent the maintenance cost and loss cost of F-SOP, respectively. This represents the operation and maintenance cost coefficient; Indicates F-SOP number z porte Apparent power transmitted in phase; Indicates the grid electricity price; Indicates the total loss of F-SOP;

[0032] ②Comprehensive operating cost of commutator

[0033] (7)

[0034] In the formula: , These represent the operating cost and loss cost of the commutator, respectively. This is the commutator operation cost coefficient; A 0-1 variable, representing the first... The operating status of the commutator, 0 and 1 represent the commutator being in operation and not operating, respectively; This indicates the total loss of the commutator;

[0035] ③ OLTC overall operating cost

[0036] (8)

[0037] In the formula: , These represent the operating cost and depreciation cost of OLTC, respectively. This is the cost coefficient for OLTC actions; This is a variable indicating changes in OLTC gear levels between adjacent time periods; This indicates the total power transmission loss of the OLTC;

[0038] ④CB operating costs

[0039] (9)

[0040] In the formula: This is the commutator operation cost coefficient; This is an identifier variable representing the change in CB compensation capacity between adjacent time periods;

[0041] ⑤ Three-phase four-wire network loss cost

[0042] (10)

[0043] In the formula: This represents the total loss of a three-phase four-wire network;

[0044] 2) Three-phase imbalance

[0045] (11)

[0046] In the formula, For the first nThe maximum value of the three-phase output power of the OLTC; For the first n The average value of the three-phase output power of the OLTC unit;

[0047] 3) Overall voltage deviation

[0048] (12)

[0049] In the formula: For nodes of e Phase voltage; This serves as the reference voltage for the power distribution network. Indicates the number of nodes in the distribution radio area; It represents a single moment in the runtime cycle.

[0050] This invention proposes a multi-timescale, multi-resource collaborative scheduling method for low-voltage interconnected distribution areas. Based on establishing mathematical models of multi-resource losses such as F-SOP and OLTC, a multi-timescale, multi-resource collaborative scheduling model for low-voltage interconnected distribution areas is constructed. In the long-timescale optimization stage, this model determines the switching schemes for passive devices such as OLTC and CB and transmits this information to the short-timescale optimization stage. Based on this, the short-timescale stage determines the short-timescale action schemes for active resources such as F-SOP and commutators within the day. Integrating the optimization results of the two stages yields the optimal collaborative scheduling result. When controlling multiple devices, this invention fully considers the differences in source-load uncertainty fluctuations at different timescales, as well as the differences in response speed between traditional mechanical devices, F-SOP, and commutators. A multi-resource, multi-timescale collaborative optimization strategy is established. This strategy not only effectively reduces the overall power loss of low-voltage interconnected distribution areas while ensuring the economic operating range of OLTC and three-phase balance constraints, but also achieves comprehensive management of global three-phase imbalance and light / heavy load issues in the distribution area, thereby realizing multi-objective comprehensive management of interconnected distribution areas. Attached Figure Description

[0051] Figure 1 This is a flowchart of the multi-time-scale, multi-resource collaborative scheduling method for low-voltage interconnected distribution areas provided by the present invention;

[0052] Figure 2 This is the interconnected network architecture of the embodiment of the present invention;

[0053] Figure 3 This is the F-SOP topology in the embodiments of the present invention;

[0054] Figure 4 This is the commutator topology in the embodiments of the present invention;

[0055] Figure 5This is the overall framework for multi-timescale integrated regulation in the embodiments of the present invention;

[0056] Figure 6 This is a diagram of the interconnected station node architecture in an embodiment of the present invention;

[0057] Figure 7 This is a schematic diagram showing the distribution of network losses in various scenarios according to embodiments of the present invention;

[0058] Figure 8 This is a schematic diagram of the total system loss distribution in each scenario of the present invention (in the figure, (a) is a schematic diagram of the total system loss distribution in scenario 1; (b) is a schematic diagram of the total system loss distribution in scenario 2; and (c) is a schematic diagram of the total system loss distribution in scenario 3).

[0059] Figure 9 These are load rate curves of OLTCs in various scenarios according to embodiments of the present invention (in the figure, (a) is the load rate curve of OLTC in scenario 1; (b) is the load rate curve of OLTC in scenario 2; and (c) is the load rate curve of OLTC in scenario 3).

[0060] Figure 10 These are output power three-phase imbalance curves of OLTC in various scenarios according to the embodiments of the present invention (in the figure, (a) is the output power three-phase imbalance curve of OLTC in scenario 1; (b) is the output power three-phase imbalance curve of OLTC in scenario 2; and (c) is the output power three-phase imbalance curve of OLTC in scenario 3). Detailed Implementation

[0061] To facilitate understanding by those skilled in the art, the present invention will be further described below with reference to embodiments and accompanying drawings. The content mentioned in the embodiments is not intended to limit the present invention.

[0062] like Figure 1 As shown, the multi-time-scale, multi-resource collaborative scheduling method for low-voltage interconnected distribution areas provided by this invention mainly includes six steps, as follows:

[0063] Step S1: Construct a low-voltage interconnected distribution substation architecture, including multiple adjustable resources such as CB, OLTC, F-SOP, and commutator, as well as a loss model for key equipment.

[0064] Step S2: Construct a multi-timescale, multi-resource collaborative scheduling model for low-voltage interconnected distribution areas with the objectives of optimal system operation economy, optimal three-phase imbalance, and optimal overall voltage deviation. The solution process of this model is divided into a long-timescale optimization stage and a short-timescale optimization stage. In the long-timescale optimization stage, the model is constrained by the characteristics of key system equipment and the power flow security of system operation. In the short-timescale optimization stage, the model is constrained by the characteristics of key system equipment, the power flow security of system operation, and the long-short-timescale adjustment amount.

[0065] Step S3: Collect power distribution network source and load data on both long and short time scales;

[0066] Step S4: Input the long-term distribution network source-load data into the multi-time-scale multi-resource collaborative scheduling model, solve the long-term optimization stage results, and obtain the OLTC and CB action schemes.

[0067] Step S5: Input the short-timescale distribution network source-load data and the obtained OLTC and CB action schemes into the multi-timescale multi-resource collaborative scheduling model, solve the short-timescale optimization stage results, and obtain the F-SOP and commutator action schemes.

[0068] Step S6: Integrate the OLTC and CB action schemes and the F-SOP and commutator action schemes to obtain the multi-timescale multi-resource collaborative scheduling results for low-voltage interconnected distribution areas.

[0069] Furthermore, in step S1, when constructing the low-voltage interconnected distribution substation architecture and key equipment loss model:

[0070] 1) Determine the network architecture of the interconnected areas

[0071] In this embodiment, the three-phase four-wire low-voltage interconnection network based on F-SOP and commutator is as follows: Figure 2 As shown. Taking a two-port F-SOP as an example, the two low-voltage distribution substation buses are connected to the two ports of the F-SOP respectively. On the line side of the distribution substation, some nodes are connected to commutators. ACLoad1~ACLoad6 represent various types of loads on the two substation buses, and the power of each load is positive in the direction of outflow from the bus. Figure 2 In the diagram, DN1 and DN2 represent 10kV distribution substations; T1 and T2 represent OLTCs with a transformation ratio of 10 / 0.4kV, and CBs are connected at this location. , They represent the first Taiwan OLTC e ( e The active and reactive power output of phases a, b, or c are both positive in the direction of flowing into the busbar. , These represent the F-SOP number z port e The active and reactive power transmitted in each phase are also positively oriented in the direction flowing into the bus.

[0072] 2) Determine the F-SOP topology and loss characteristic model

[0073] F-SOP topology as follows Figure 3 As shown, the ports of the F-SOP are independent of each other, and the loss is mainly determined by the port's transmission power and transmission efficiency. Assuming the transmission efficiency of each arm of the F-SOP is constant, the calculation formula is as follows:

[0074] (13)

[0075] In the formula: Indicates the total loss of F-SOP; This indicates the third phase four-arm F-SOP. z port e Transmission power of the bridge arm; Indicates F-SOP z port e Power transmission efficiency of the bridge arm.

[0076] 3) Determine the commutator topology and loss characteristic model.

[0077] The principle of a commutator can be simplified to a single-pole three-throw switch, such as... Figure 4 As shown in the figure, These represent the three-phase voltage amplitudes at the commutator grid connection point; This represents the amplitude of the current flowing through the user, which remains constant before and after commutation. In practical applications, the losses of the commutator are closely related to the magnitude of the commutation load, and their losses are expressed as:

[0078] (14)

[0079] In the formula: This indicates the total loss of the commutator; This represents the resistance coefficient of the commutator; Indicates the first m Apparent power of the commutation load at the commutator access node.

[0080] 4) Determine the OLTC loss characteristic model

[0081] As an important piece of equipment in a distribution substation, the power loss of an OLTC can account for 40% to 70% of the total system loss. The formulas for calculating its load rate and the lower limit of its economic operating range are as follows:

[0082] (15)

[0083] In the formula: OLTC load rate; This represents the lower limit of the OLTC economic operating range. These represent the total active and reactive power outputs of the OLTC three-phase system, respectively. This refers to the total capacity of the three-phase OLTC. The total no-load power loss of OLTC; The overall power rated load loss of the OLTC; This is the load fluctuation coefficient.

[0084] OLTC total power transmission loss Represented as:

[0085] (16)

[0086] In the formula: For the first n OLTC Taiwan e Phase-to-phase power no-load loss; For the first n OLTC Taiwan e Phase-to-phase power rated load loss; For the first n OLTC load rate; For the first n The zero-sequence loss generated by an unbalanced three-phase load on an OLTC (Optical Logic Controller) is calculated using the following formula:

[0087] (17)

[0088] In the formula: For the first i Taiwan OLTC neutral point current, For the first i OLTC zero-sequence resistor.

[0089] 5) Determine the loss characteristic model of a three-phase four-wire power flow network.

[0090] The formulas for calculating the independent network loss of the three phases and the zero-sequence loss of the neutral line are as follows:

[0091] (18)

[0092] In the formula: express e Phase network loss; This indicates the zero-sequence loss at the neutral line. 、 Indicates the node number; for e Mutually The current in the branch circuit; for e Mutually The resistance of the branch circuit; For nodes Zero-sequence current flowing through the neutral line; For nodes The resistance of the neutral line; the zero-sequence voltage at the node in the formula. and neutral zero-sequence current The calculation formula is as follows:

[0093] (19)

[0094] In the formula: express The three-phase voltages of node a, b, and c; Representing nodes respectively , The zero-sequence voltage; This is the zero-sequence voltage conversion factor.

[0095] Combining equations (18) and (19), the total loss of the three-phase four-wire network is:

[0096] (20)

[0097] In the formula: This represents the total loss of a three-phase four-wire network. for e Mutually The current in the branch circuit; for e Mutually Branch resistance.

[0098] As described above, the multi-timescale, multi-resource collaborative scheduling method for low-voltage interconnected distribution substations proposed in this invention takes low-voltage interconnected distribution substations with multiple adjustable resources such as CB, OLTC, F-SOP, and commutators as the research object. To fully coordinate and utilize the different response speeds of various resources—OLTC and CB being passive devices with slow operating timescales, and FSOP and commutators being active devices with continuously controllable power and fast response speeds—this invention proposes a multi-timescale, multi-resource collaborative scheduling model divided into a long-timescale optimization stage and a short-timescale optimization stage. The long-timescale can be 1 hour, and the short-timescale can be 15 minutes or 5 minutes. For more information on the multi-timescale, multi-resource collaborative scheduling model of this invention, please refer to [link to relevant documentation]. Figure 5First, in the long-term optimization phase, under the characteristic constraints of mechanical passive devices such as OLTC and CB, and the power flow safety constraints of system operation, optimization and control are performed with the goal of achieving the best overall system operation effect. The OLTC and CB action schemes are determined and transmitted to the short-term optimization phase. In the short-term phase, this invention employs a multi-scenario stochastic programming method to consider the uncertainty of each phase load and predict the active and reactive loads of each phase. Based on this, system operation safety constraints and power flow constraints are set under the short-term control cycle, as well as power flow constraints that unify the OLTC node voltage and CB reactive power input in the short-term optimization phase with those in the long-term phase. This determines the F-SOP and commutator action schemes under the short-term phase to address the problems of long OLTC and CB tap changer control cycles and difficulties in real-time source-load matching. Finally, the optimization results of the two phases are integrated to form a multi-time-scale, multi-resource collaborative scheduling model.

[0099] The multi-time-scale, multi-resource collaborative scheduling model in this invention aims to optimize system operation economy, three-phase imbalance, and overall voltage deviation. The objective function obtained is as follows:

[0100] (4)

[0101] In the formula: These are the weighting factors for the objectives of economy, three-phase imbalance, and overall voltage deviation, respectively. These are the measured overall operating cost of the system, three-phase imbalance, and overall voltage deviation, respectively. The weights for the targets of economy, three-phase imbalance, and overall voltage deviation are respectively. These are the initial values ​​of the economic efficiency, three-phase imbalance, and overall voltage deviation targets before optimization;

[0102] 1) Economic objectives of the distribution area

[0103] (5)

[0104] In the formula: The overall operating cost of the system; The total operating cost of F-SOP includes F-SOP maintenance costs and depreciation costs; The total operating cost of the commutator includes the cost of commutator operation and loss. The total cost of OLTC includes depreciation costs and operating costs; Cost of CB action; Cost of loss in a three-phase four-wire network;

[0105] ①F-SOP Overall Operating Cost

[0106] In actual operation, the operating cost of F-SOP needs to take into account both maintenance costs and loss costs.

[0107] (6)

[0108] In the formula: , These represent the maintenance cost and loss cost of F-SOP, respectively. This represents the operation and maintenance cost coefficient; Indicates F-SOP number z port e Apparent power transmitted in phase; Indicates the grid electricity price; Indicates the total loss of F-SOP;

[0109] ②Comprehensive operating cost of commutator

[0110] As a discrete-action device, the cost of a commutator mainly consists of operating costs and loss costs.

[0111] (7)

[0112] In the formula: , These represent the operating cost and loss cost of the commutator, respectively. This is the commutator operation cost coefficient; A 0-1 variable, representing the first... m The operating status of the commutator, 0 and 1 represent the commutator being in operation and not operating, respectively; This indicates the total loss of the commutator;

[0113] ③ OLTC overall operating cost

[0114] (8)

[0115] In the formula: , These represent the operating cost and depreciation cost of OLTC, respectively. This is the cost coefficient for OLTC actions; This is a variable indicating changes in OLTC gear levels between adjacent time periods; This indicates the total power transmission loss of the OLTC;

[0116] ④CB operating costs

[0117] (9)

[0118] In the formula: This is the commutator operation cost coefficient; This is an identifier variable representing the change in CB compensation capacity between adjacent time periods;

[0119] ⑤ Three-phase four-wire network loss cost

[0120] (10)

[0121] In the formula: This represents the total loss of a three-phase four-wire network;

[0122] 2) Three-phase imbalance

[0123] The target for three-phase imbalance is as follows:

[0124] (11)

[0125] In the formula, For the first n The maximum value of the three-phase output power of the OLTC; For the first n The average value of the three-phase output power of the OLTC unit;

[0126] 3) Overall voltage deviation

[0127] (12)

[0128] In the formula: For nodes of e Phase voltage; This serves as the reference voltage for the power distribution network. Indicates the number of nodes in the distribution radio area; It represents a single moment in the runtime cycle.

[0129] The aforementioned preferred embodiment, in this embodiment, has the following constraints for the multi-timescale, multi-resource collaborative scheduling model during the long-timescale optimization phase:

[0130] ① Operational constraints of three-phase four-wire network

[0131] The operational constraints of a three-phase four-wire network include two parts: power flow constraints and operational safety constraints.

[0132] Power flow constraints are represented as follows:

[0133] (2)

[0134] In the formula: , They represent Active power and reactive power injected into each phase of the node; , They are respectively Active power and reactive power of the branch circuit; , They are respectively Active power and reactive power of the branch circuit; , They are respectively , Nodes e Phase voltage; Indicates the flow of electricity to the node The set of all upstream nodes to which power is injected; , indicating from node The set of all downstream nodes to which the outflowing power reaches via the power grid; Indicates the reactance of each phase of the circuit; Indicates the resistance of each phase of the circuit; Represented as e Mutually The current in the branch circuit; Indicates the conductance of each phase of the circuit; Indicates the susceptance of each phase of the circuit;

[0135] The original network power flow model is a nonlinear programming model. To improve the solution rate, this invention performs a two-step relaxation:

[0136] ① Order That is, define new optimization variables - the square of the node voltage magnitude and the square of the current magnitude, thereby eliminating the influence of the phase angle on the power flow calculation;

[0137] ② Using the second-order cone relaxation technique, the original non-convex constraints are transformed into convex constraints, thus becoming linear and solvable. The power flow constraints of the system after transformation are shown below:

[0138] (3).

[0139] The operational safety constraints of each phase in a three-phase four-wire independent network are expressed as follows:

[0140] (twenty one)

[0141] In the formula, and These are the upper and lower limits of the node voltage, respectively. This is the upper limit of the branch current magnitude. and These are the upper and lower limits of the injected node power, respectively.

[0142] ②F-SOP Operating Constraints

[0143] The F-SOP has the ability to independently control the three-phase power, enabling it to achieve power transfer between phases at a single node. Therefore, the operating constraint of the F-SOP only needs to ensure that the sum of the input power and output power of all phases is zero. The difference from the traditional SOP is that it no longer needs to consider the input and output power balance within each phase.

[0144] (twenty two)

[0145] In the formula, Indicates F-SOP number z port e Active power flowing out of the phase; These represent the F-SOP number z port e Apparent power, active power, and reactive power flowing through the bridge arm; Indicates F-SOP number z port e The capacity of the bridge arm.

[0146] ③Commutator operating constraints

[0147] The principle of a commutator is to achieve a more balanced three-phase load by switching the load of one phase to another. Simultaneously, it does not alter the original power flow network architecture of the system. The commutator used in this invention can switch the load of phase a of a corresponding node to phase b or phase c. Its constraints are as follows:

[0148] (twenty three)

[0149] In the formula, For the first m A commutator for a certain node e Active power injected into the phase; For the first m A commutator for a certain node e Phase-injected reactive power; Indicates the first m The scalar value representing the operating status of the phase commutator; and For the first m The active and reactive power of phase a load at the node connected to the phase commutator.

[0150] ④OLTC operating constraints

[0151] According to the "Distribution Network Operation and Maintenance Regulations," to ensure the safe and stable operation of the OLTC, the OLTC load rate should not exceed 75%. Under the collaborative control strategy of this invention, the OLTC needs to meet the economic operating range constraint, as shown below:

[0152] (twenty four)

[0153] In the formula, Indicates the first n The load rate of the OLTC.

[0154] With the addition of OLTC, the substation bus node voltage becomes an adjustable variable, requiring the following replacements:

[0155] (25)

[0156] In the formula: For OLTC high voltage side e The phase voltage value is a constant. The square of the upper and lower limits of the adjustable ratio of OLTC; The squared ratio of OLTC is defined as the ratio of the quadratic side to the linear side. It is actually a discrete-valued variable and can be further processed into the following relationship containing 0-1 variables:

[0157] (26)

[0158] In the formula: Represented as the first SR Each gear's 0-1 identifier variable; This indicates the OLTC gear adjustment change indicator, which is a 0-1 variable. Then the OLTC gear value is in the 1st position. t Time period t The value of the -1 time period is large. similar; This represents the maximum range of gear changes.

[0159] ⑤CB running constraints

[0160] (27)

[0161] In the formula: for Time Node The CB received e The reactive power compensation of the phase; The number of operational groups represents the value of a discrete variable. The compensation power for each CB group is constant; For nodes Maximum number of connected CB groups; The upper limit of the number of groups that node j connects to CB in adjacent time periods.

[0162] Furthermore, the absolute value constraint in the above formula can be addressed by adding an auxiliary variable that characterizes the change in CB compensation capacity between adjacent time periods. Then we can obtain:

[0163] (28)

[0164] ⑥ Power balance constraints

[0165] (29)

[0166] In the formula: These represent the injected active and reactive power at each node of the distribution radio area.

[0167] In the aforementioned preferred embodiment, the constraints of the multi-timescale multi-resource collaborative scheduling model in the short-timescale optimization stage are three-phase four-wire network operation constraints, F-SOP operation constraints, commutator operation constraints, and power balance constraints. These constraints are the same as those in the aforementioned equations (2), (3), (21)-(23), and (29), and will not be repeated here. In addition, long-short timescale adjustment constraints are also considered in this stage. The constraints on the short-timescale operation state changes of F-SOP and commutator based on the long-timescale operation state are as follows:

[0168] (1)

[0169] In the formula: , These are F-SOP access nodes for long and short time scales, respectively. VSC in e Active power transmitted in phase; For F-SOP access nodes VSC in e The maximum operable active power for long-term, short-timescale transmission; , These are F-SOP access nodes for long and short time scales, respectively. VSC in e The reactive power transmitted in phase; For F-SOP access nodes VSC in e The maximum operable reactive power quantity for long-term, short-time-scale transmission; , They are respectively the long and short time scales. m The scalar value representing the operating status of the phase commutator; For the first m The maximum operable quantity of the commutator.

[0170] For solving the multi-timescale, multi-resource collaborative scheduling model in the long- and short-timescale optimization stages, since both stages involve mixed-integer second-order cone programming, the CPLEX commercial solver can be directly used. Based on the long-timescale distribution network source-load data, the OLTC and CB action schemes are determined and transferred to the short-timescale stage. Based on the short-timescale distribution network source-load data, the F-SOP and commutator action schemes are determined. Finally, the action schemes of each device in the long- and short-timescale stages are integrated to form the multi-timescale, multi-resource collaborative scheduling result for low-voltage interconnected distribution areas.

[0171] To verify the effectiveness and superiority of the method involved in this invention, this embodiment uses... Figure 6 Taking the low-voltage interconnected distribution area shown as an example, the method of the present invention is used to formulate the operation strategy of each device and to regulate the power flow of the low-voltage interconnected distribution area. To meet the verification needs of the present invention, the two ends of the F-SOP are connected to the root nodes 22 and 37, and both are connected to the OLTC and CB at the root nodes. The commutators are installed at nodes 12, 17, 34 and 36. The calculation parameters are shown in Table 1.

[0172] Table 1. Parameter Table for Transmission Area

[0173] ;

[0174] To verify the effectiveness and accuracy of the method proposed in this invention, three planning methods and scenarios were set up.

[0175] Scenario 1: This is a blank control group. The system has no OLTC, CB, F-SOP, or commutator.

[0176] Scenario 2: This is a traditional solution where the system only includes F-SOP and commutator, and only performs long-term scheduling.

[0177] Scenario 3: The solution of this invention, the system simultaneously includes OLTC, CB, F-SOP and commutator, and performs multi-timescale coordinated operation.

[0178] Table 2 compares the costs of various items in three scenarios under the IEEE 33-node example. Regarding the operating costs of critical equipment, the maintenance costs increase slightly due to the participation of various devices in scheduling, but the magnitude and proportion of the increase are relatively small. In terms of OLTC loss and network loss costs, the costs controlled by the method of this invention are minimized. The network loss cost of the method of this invention is reduced by 29.63% and 27.16% compared to scenarios 1 and 2, respectively. Therefore, the method proposed in this invention has significant loss reduction and economic optimization effects.

[0179] Table 2. Operating cost results for each scenario

[0180] ;

[0181] Figure 7 The diagrams show the system network loss under three scenarios. As can be seen from the diagrams, although the overall operating cost of F-SOP and the commutator is increased in the scenario described in this invention, the overall system operating cost is also significantly lower than in the other scenarios due to the significantly lower total loss, resulting in optimal economic efficiency. Furthermore, in the long run, this invention effectively addresses the three-phase imbalance and light / heavy load issues across the entire transformer area, improving system operational safety, extending equipment lifespan, and enhancing the long-term economic efficiency of the system.

[0182] Figure 8 The total system loss and loss composition are shown in three scenarios. Scenario 1, such as... Figure 8 As shown in (a), since the two substations are not interconnected by F-SOP and the commutator is not used for phase switching, the OLTC bears the entire load. This leads to the OLTC's zero-sequence loss and line loss being prominent, resulting in a large total loss. In scenario 2, as... Figure 8 As shown in (b), after connecting multiple control devices, the three-phase imbalance and light / heavy load of the OLTC are addressed, and the OLTC loss is significantly reduced. However, long-term planning schemes are insufficient to cope with short-term load fluctuations, and line losses remain prominent. In scenario 3, as... Figure 8 As shown in (c), with the comprehensive management of OLTC, CB, F-SOP and commutator, both OLTC loss and line loss are significantly reduced. During the peak load periods at noon and in the evening, network loss can be reduced by about 30% to 45%, and at other times, network loss can be reduced by 15% to 30%. The total loss is the smallest among the three schemes, and the management effect is the best.

[0183] Figure 9 The graphs show the OLTC load rate curves under three scenarios. Figure 9 As shown in (a), in scenario 1, the OLTC access point lacks power compensation from the control equipment, and during peak electricity consumption periods in the daytime and evening, the load rate of both OLTCs exceeds the economic operating range; Figure 9 As shown in (b), in scenario 2, due to intraday load fluctuations, the day-ahead scheduling schemes F-SOP and CB exhibit no reactive power overcompensation, making it difficult to cope with changes in the OLTC load rate, reaching 67.43% at 20:00; while in scenario 3, as... Figure 9 As shown in (c), the low-voltage busbar of the transformer area is connected to F-SOP, and the OLTC operates within the economic operating range at all times.

[0184] Figure 10 The output power three-phase imbalance curves of the OLTC are shown in three scenarios. Figure 10 As shown in (a), in scenario 1, when there is no adjustable device to address the three-phase imbalance, the three-phase imbalance problem of the OLTC is severe, and the imbalance of the OLTC output power can reach up to 60%; in scenario 2, as Figure 10As shown in (b), the low-voltage buses of the two distribution areas are connected to F-SOP. Under the synergistic effect of OLTC and CB, the three-phase imbalance of OLTC output power is significantly reduced. However, due to the continuous fluctuation of the load in the low-voltage distribution area, the three-phase imbalance often approaches the limit under the long-term scale of the scheme. In scenario 3, as shown in... Figure 10 As shown in (c), the OLTC, CB, F-SOP and commutator work together on multiple time scales to play a role in controlling the imbalance at both the OLTC end and the line load side, so that the three-phase imbalance is within the threshold at all times.

[0185] The above embodiments are preferred implementations of the present invention. In addition, the present invention can be implemented in other ways. Any obvious substitutions without departing from the concept of the present technical solution are within the protection scope of the present invention.

[0186] To facilitate understanding by those skilled in the art of the improvements of this invention over the prior art, some of the accompanying drawings and descriptions have been simplified, and for clarity, some other elements have been omitted from this application. Those skilled in the art should realize that these omitted elements may also constitute the content of this invention.

Claims

1. A multi-time-scale, multi-resource collaborative scheduling method for low-voltage interconnected distribution areas, characterized in that: include: Step S1: Construct a low-voltage interconnected distribution substation architecture that includes multiple adjustable resources such as CB, OLTC, F-SOP, and commutator, as well as a loss model for key equipment. Step S2: With the goals of optimal system operation economy, optimal three-phase imbalance, and optimal overall voltage deviation, a multi-time-scale multi-resource collaborative scheduling model for low-voltage interconnected distribution areas is constructed. The solution process of this model is divided into a long-term optimization stage for solving the OLTC and CB action schemes based on long-term distribution network source and load data, and a short-term optimization stage for solving the F-SOP and commutator action schemes based on short-term distribution network source and load data. Step S3: Collect distribution network source and load data at both long and short time scales. First, input the long-term distribution network source and load data into the multi-time scale multi-resource collaborative scheduling model to solve for the OLTC and CB action schemes. Then, input the short-term distribution network source and load data into the multi-time scale multi-resource collaborative scheduling model to solve for the F-SOP and commutator action schemes. Finally, integrate the OLTC, CB, F-SOP, and commutator action schemes to obtain the multi-time scale multi-resource collaborative scheduling results for low-voltage interconnected distribution areas.

2. The multi-time-scale, multi-resource collaborative scheduling method for low-voltage interconnected distribution areas according to claim 1, characterized in that: In the short-timescale optimization stage, a multi-scenario stochastic programming method is adopted to consider the uncertainty of the load of each phase in order to predict the active and reactive loads of each phase.

3. The multi-time-scale, multi-resource collaborative scheduling method for low-voltage interconnected distribution areas according to claim 2, characterized in that: The constraints of the multi-timescale multi-resource collaborative scheduling model in the long-timescale optimization stage include three-phase four-wire network operation constraints, F-SOP operation constraints, commutator operation constraints, OLTC operation constraints, CB operation constraints, and power balance constraints.

4. The multi-time-scale, multi-resource collaborative scheduling method for low-voltage interconnected distribution areas according to claim 3, characterized in that: The constraints of the multi-timescale multi-resource collaborative scheduling model in the short-timescale optimization stage include three-phase four-wire network operation constraints, F-SOP operation constraints, commutator operation constraints, power balance constraints, and long-short timescale adjustment constraints.

5. The multi-time-scale, multi-resource collaborative scheduling method for low-voltage interconnected distribution areas according to claim 4, characterized in that: The long-short timescale adjustment constraint is a constraint on F-SOP and the commutator's short-timescale operating state changes based on the long-timescale operating state, as shown in the following formula: (1) In the formula: , These are F-SOP access nodes for long and short time scales, respectively. VSC in Active power transmitted in phase, Phase refers to phase a, b, or c; For F-SOP access nodes VSC in The maximum operable active power for long-term, short-timescale transmission; , These are F-SOP access nodes for long and short time scales, respectively. VSC in The reactive power transmitted in phase; For F-SOP access nodes VSC in The maximum operable reactive power quantity for long-term, short-time-scale transmission; , They are respectively the long and short time scales. The scalar value representing the operating status of the phase commutator; For the first The maximum operable quantity of the commutator.

6. The multi-time-scale, multi-resource collaborative scheduling method for low-voltage interconnected distribution areas according to claim 5, characterized in that: The operating constraints of the three-phase four-wire network include power flow constraints, which are expressed as follows: （2） In the formula: , They represent The active and reactive power injected into each phase of the node; , They are respectively Active power and reactive power of the branch circuit; , They are respectively Active power and reactive power of the branch circuit; , They are respectively , Nodes Phase voltage; Indicates the flow of electricity to the node The set of all upstream nodes to which power is injected; , indicating from node The set of all downstream nodes to which the outflowing power reaches via the power grid; Indicates the reactance of each phase of the circuit; Indicates the resistance of each phase of the circuit; Represented as Mutually The current in the branch circuit; Indicates the conductance of each phase of the circuit; Indicates the susceptance of each phase of the circuit; make Using the second-order cone relaxation method, the non-convex constraint in equation (2) is transformed into a convex constraint, and then solved linearly. The transformed power flow constraint is as follows: （3）。

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