Hierarchical Planning Method for Distribution Network Voltage and Reactive Power of Pumped Storage Power Generation Construction Power Supply System

Abstract

A method for hierarchical planning of distribution network voltage and reactive power in a pumped-storage power construction power supply system, which successively passes through steps of overall model, objective function, constraint conditions, operation constraints and solution. The upper investment layer adopts a planning scheme that focuses on planning and constructing equipment, with the goal of minimizing the total investment cost and operation cost. The lower layer is the voltage and reactive power optimization layer, which focuses on optimizing the optimal operation scheme of the distribution network, considering equipment and system operation constraints, and aiming at minimizing the operation cost of the distribution network. Finally, through repeated iteration and solution of IPSO, the optimal planning scheme result of the distribution network is obtained, so as to solve the problems of large reactive power loss in the distribution network lines and unstable terminal voltage in the pumped-storage power station construction power supply system, improve the terminal voltage level and improve the power quality of the system.

Description

Technical Field

[0001] The present invention belongs to the technical field of pumped-storage power supply, and relates to a method for hierarchical planning of distribution network voltage and reactive power of a construction power supply system for pumped storage. Background Art

[0002] To ensure the normal operation of the power system and provide reliable electric energy, a large number of adjustable power sources are often required. As a relatively mature, economical, and large-scale developable green and highly flexible adjustable power source at present, pumped-storage power stations play an important role in peak shaving and frequency modulation, accident response, local energy consumption, energy conservation and emission reduction. However, the construction of pumped-storage power stations generally has the characteristics of large scale, long construction period, relatively scattered layout of construction facilities, many load points and large capacity during the construction period, and scattered layout, long power supply distance, etc.

[0003] Generally speaking, the construction power supply system of a pumped-storage power station mainly undertakes the construction electricity consumption of projects such as the upper reservoir, the lower reservoir, the camp area, and the sand and gravel area system. The construction power supply system of a pumped-storage power station is mainly responsible for the stable power supply of various types of loads such as construction machinery, lighting, compressed air, water supply and drainage, sand and gravel processing, and concrete production at the end of each area. The long power supply radius and complex fluctuating loads are likely to cause reactive power loss in the line and unstable terminal voltage. Special equipment such as rotating equipment and electric welders need to absorb active and reactive power from the power system during normal operation to generate the necessary alternating magnetic field for the equipment. However, when the system transmits a certain amount of active power, the increase in reactive power will reduce the power factor of the system and reduce the energy utilization rate. Therefore, solving the above-mentioned terminal power quality support will provide a great development foundation for the development of the key technologies of the construction power supply system of pumped-storage power stations. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a method for hierarchical planning of distribution network voltage and reactive power of a construction power supply system for pumped storage, which mainly includes a high-voltage construction access substation, a medium-voltage distribution network unit, a low-voltage distribution transformer corresponding to different electrical loads, various types of electrical loads in some areas of the upper reservoir area, the camp area, the lower reservoir area, the sand and gravel area, and the end of each area. At the same time, it includes various voltage and reactive power compensation devices such as DG, capacitor banks, SVG, and OLTC, so as to realize the economic design of the entire construction power supply system, and a flexible diesel generator backup power supply is used in the construction power supply system to compensate the energy of the entire power supply system.

[0005] To solve the above technical problems, the technical solution adopted by the present invention is: a method for hierarchical planning of distribution network voltage and reactive power of a construction power supply system for pumped storage, which includes the following steps:

[0006] S1, overall model, the objective function mainly includes the planning investment cost ( CINV ) and the planned operation cost ( C OPE ) The upper-layer model is a planning scheme that makes decisions with the goal of minimizing the investment cost for the siting and sizing problems of DG, capacitor banks, SVG, and OLTC equipment in the distribution network. The lower-layer model optimizes the operation variables of the distribution network with the goal of minimizing the planned operation cost based on the upper-layer decision results. The hierarchical planning model of the distribution network is expressed as:

[0007] (1)

[0008] In the formula: and are the upper and lower layer objective functions; and and and are the upper and lower layer constraint conditions; x inv and x ope are the investment decision variable and the simulation operation variable respectively. It can be seen from formula (1) that this model is a one-way two-layer model, that is, the upper-layer model transmits state variables to the lower layer, and the variable decision of the lower layer affects the upper layer, which is reflected by adding the operation cost to the upper-layer constraints;

[0009] S2, objective function, (2)

[0010] In the formula: L ij is the length of branch ij ; l is the equipment type identifier; and and and and and are the sets of candidate nodes for the corresponding investment equipment; and and and and and are the sets of candidate types for the corresponding investment equipment; and and and and and are the unit investment cost coefficients of the corresponding investment equipment; and and and and and Indicates whether the corresponding investment equipment is installed or the installation quantity. This item is the decision variable corresponding to the investment layer, where is an integer variable, and the rest are all 0-1 variables. represents whether to invest in the transformer tap;

[0011] S3, constraint conditions

[0012] S3-1, equipment selection constraint

[0013] (4)

[0014] This constraint indicates that the selection of transformer capacity, line, BESS, and SVG is unique, and each node can only select one model from the set of candidate types for investment;

[0015] S3-2, limit on the number of installation nodes of grouped capacitors;

[0016] (5)

[0017] In the formula is the installation quantity of CB at j the node, M CB is the limit value of the installation quantity of CB at each node;

[0018] S4, operation constraints, including power flow constraints, security constraints, transformer node power constraints, OLTC constraints, BESS operation constraints, CB operation constraints, static var compensator SVG operation constraints, DG-related constraints, and load shedding constraints;

[0019] S5, solution

[0020] S5-1, with the goal of minimizing the planned investment cost, use IPSO to solve the equipment investment site selection and capacity determination model to obtain the results related to the investment planning cost and the distribution network decision-making plan;

[0021] S5-2, based on the distribution network decision-making plan in S5-1, with the goal of minimizing the planned operation cost, use IPSO to solve the equipment investment operation cost to obtain the lower-layer optimization results, including the results related to the distribution network operation plan and the investment operation cost;

[0022] S5-3, according to the results related to the distribution network operation plan in S5-2, solve the equipment investment site selection and capacity determination model considering the distribution network investment operation to obtain the planned cost, the upper-layer optimization results, and the total investment cost;

[0023] S5-4, iterative optimization of the upper and lower layers until the termination condition is met.

[0024] In S2, the curtailment of wind power, curtailment of solar power, and load shedding costs are mainly added to the operating costs, and the operating costs of each active management unit (OLTC, BESS, CB, and SVG) of the distribution network are also considered.

[0025] (3)

[0026] Where: ω is the conversion factor between the operating cost and the investment cost; E is the set of lines; B TR , B WTG , B PVG , B Load are the sets of all transformer nodes, wind power nodes, photovoltaic power nodes, and load nodes in the system, respectively; and are the branch current and resistance, respectively; ∆ t is the time interval; , are the wind power and photovoltaic power generation data; , , , , , , , , are the unit prices of network loss, main grid power purchase, wind power curtailment, solar power curtailment, load shedding penalty, OLTC regulation, CB switching, SVG operation, and BESS operation, respectively; , , and represent the main grid output, wind power output, photovoltaic power output, and load shedding active power, respectively, and are part of the decision variables corresponding to the operation layer. In addition, the decision variables also include control variables based on the distribution network equipment such as OLTC, BESS, CB, and SVC; , , , are the OLTC regulation amount, CB switching amount, SVG regulation amount, and BESS regulation amount, respectively.

[0027] In S4, the power flow constraint,

[0028] (6)

[0029] (7)

[0030] (8)

[0031] Wherein: x ij is the reactance of branch ij ; B is the set of all nodes in the system, B BESS , B OLTC , B CB and B SVC are the sets of nodes connected with BESS, OLTC, CB and SVG respectively; is the set of end nodes of the branch with j as the start node; is the set of start nodes of the branch with j as the end node; is the voltage of node j at the t th time period; , are the active power and reactive power of branch ij at the t th time period respectively; , are the charging power and discharging power of the BESS connected to node j at the t th time period respectively; is the transformation ratio of the OLTC connected to node i at the t th time period, the ratio of the secondary side to the primary side; , , are the reactive power values of the fan, CB and SVG respectively; , are the predicted reactive power value of the load and the reactive power of the load loss respectively.

[0032] In S4, the security constraint,

[0033] (9)

[0034] Wherein: , , are the upper and lower limits of the node voltage amplitude and the upper limit of the current amplitude respectively.

[0035] In S4, the power constraint of the transformer node,

[0036] (10)

[0037] Wherein: , , and are the upper and lower limits of the active power and reactive power of the transformer, respectively.

[0038] In S4, the OLTC constraint

[0039] (11)

[0040] In the formula: and are the upper and lower limits of the adjustable transformation ratio of the OLTC, respectively, is the transformation ratio of the OLTC at t time period.

[0041] In S4, the BESS operation constraints include charge and discharge constraints, power constraints, and capacity constraints;

[0042] Charge and discharge constraints;

[0043] (12)

[0044] Power constraints;

[0045] (13)

[0046] Capacity constraints;

[0047] (14)

[0048] In the formula: and are the charge and discharge states of the BESS, respectively; , , and are the upper and lower limits of the charge and discharge power of the BESS, respectively; is the state of charge of the BESS at the t time period, and are the upper and lower limits considering factors such as the BESS life; and are the charge and discharge efficiencies, respectively.

[0049] In S4, the CB operation constraint

[0050] (15)

[0051] In the formula: is the number of operating groups of the CB connected to node j at t time period; is the upper limit of the number of CB groups connected to node j ; is the compensation capacity for each group of CBs; is the upper limit of the number of operations.

[0052] In S4, the operating constraints of the static var compensator SVG

[0053] (16)

[0054] where: and are the upper and lower limits of the SVC compensation power respectively.

[0055] In S4, DG-related constraints and load shedding constraints;

[0056] DG-related constraints

[0057] (17)

[0058] takes into account the reactive power compensation capacity of DG, and its reactive power compensation capacity and are determined according to the maximum capacity of the DG converter and and the output of the DG connected to the current node j in the t time period and respectively; and are the upper limits of PV and WT outputs respectively;

[0059] Load shedding constraints

[0060] (18)

[0061] 、 are the reactive and active powers of load shedding respectively, is the upper limit value of the active power ratio of load shedding.

[0062] The main beneficial effects of the present invention are as follows:

[0063] It takes into account the voltage and reactive power optimization of the distribution network of the construction power supply system of the pumped-storage power station, realizes the economic optimal planning of the distribution network control equipment, effectively adapts to the needs of the distribution network to access DG and load growth, improves the economy of the overall planning and operation of the distribution network, and promotes the orderly economic construction investment of the distribution network.

[0064] It solves the problems of large reactive power loss in the distribution network lines and unstable terminal voltage in the construction power supply system of the pumped-storage power station; through analyzing by considering the characteristics of the construction power supply load, it optimizes the reactive power and voltage of the planning and design of the construction power supply system, thereby improving the terminal voltage level and improving the power quality of the system.

[0065] It mainly includes a high-voltage construction access substation, medium-voltage distribution network network units, low-voltage distribution transformers corresponding to different electrical loads, various types of electrical loads in the upper reservoir area, camp area, lower reservoir area, sand and gravel area, and at the end of each area.

[0066] It also includes various voltage and reactive power compensation devices such as DG, capacitor banks, SVG, and OLTC, so as to achieve an economic design of the entire construction power supply system. In the construction power supply system, a flexible diesel generator backup power supply is used to compensate the energy of the entire power supply system. BRIEF DESCRIPTION OF THE DRAWINGS

[0067] The present invention will be further described below in conjunction with the drawings and embodiments.

[0068] Figure 1 It is a structural diagram of the construction power supply system of the pumped-storage power station of the present invention.

[0069] Figure 2 It is a solution architecture diagram of the voltage and reactive power hierarchical planning method for the distribution network of the present invention.

[0070] Figure 3 It is a solution flow chart of the improved particle swarm optimization algorithm of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0071] As Figures 1 - 3 in, a voltage and reactive power hierarchical planning method for the distribution network of a pumped-storage construction power supply system includes the following steps:

[0072] S1. Overall model. The objective function mainly includes the planned investment cost ( C INV ) and the planned operation cost ( C OPE ). The upper-layer model addresses the site selection and capacity determination problems of DG, capacitor banks, SVG, and OLTC devices in the distribution network, and makes a planning scheme with the minimum investment cost as the goal. The lower-layer model, based on the upper-layer decision results, optimizes the distribution network operation variables with the minimum planned operation cost as the goal. The distribution network hierarchical planning model is expressed as:

[0073] (1)

[0074] In the formula: , are the upper and lower layer objective functions; , , and are the upper and lower layer constraint conditions; x inv , x opeThey are the investment decision variables and the simulation operation variables respectively; As can be seen from Equation (1), this model is a one-way two-layer model, that is, the upper layer model transfers state variables to the lower layer, and the variable decisions of the lower layer affect the upper layer, which is reflected by adding operating costs to the upper layer constraints;

[0075] S2, the objective function, (2)

[0076] In the formula: L ij is the length of the branch ij ; l is the equipment type identifier; , , , , , is the set of candidate nodes for the corresponding investment equipment; , , , , , is the set of candidate types for the corresponding investment equipment; , , , , , is the unit investment cost coefficient of the corresponding investment equipment; , , , , and represent whether the corresponding investment equipment is installed or the installation quantity. This item is the decision variable corresponding to the investment layer, where is an integer variable, and the rest are all 0-1 variables, is whether to invest in transformer tap changers;

[0077] S3, the constraint conditions,

[0078] S3-1, equipment type selection constraint,

[0079] (4)

[0080] This constraint indicates that the selection of transformer capacity, line, BESS, and SVG is unique, and each node can only select one model from the set of candidate types for investment;

[0081] S3-2, the limit on the number of installed nodes of grouped capacitors;

[0082] (5)

[0083] In the formula is the installation quantity of CB at j the node installation quantity, M CB is the limit value of the installation quantity of each node of CB;

[0084] S4. Operating constraints, including power flow constraints, security constraints, transformer node power constraints, OLTC constraints, BESS operating constraints, CB operating constraints, static var compensator SVG operating constraints, DG-related constraints, and load shedding constraints;

[0085] S5. Solving

[0086] S5-1. Taking the minimum of the planned investment cost as the goal, use IPSO to solve the equipment investment site selection and capacity determination model, and obtain the results related to the investment planning cost and the distribution network decision-making plan;

[0087] S5-2. Based on the distribution network decision-making plan of S5-1, taking the minimum of the planned operating cost as the goal, use IPSO to solve the equipment investment operating cost, and obtain the lower-layer optimization results, including the results related to the distribution network operation plan and the investment operating cost;

[0088] S5-3. According to the results related to the distribution network operation plan of S5-2, solve the equipment investment site selection and capacity determination model considering the distribution network investment operation, and obtain the planned cost, the upper-layer optimization results, and the total investment cost;

[0089] S5-4. Iterative optimization of the upper and lower layers until the termination condition is met.

[0090] In the preferred solution, in S2, the operating cost mainly adds the costs of wind curtailment, light curtailment, and load shedding, and at the same time considers the operating costs of each active management unit (OLTC, BESS, CB, and SVG) of the distribution network;

[0091] (3)

[0092] In the formula: ω is the conversion factor between the operating cost and the investment cost; E is the line set; B TR , B WTG , B PVG , B Load are respectively the set of all transformer nodes, the set of wind power nodes, the set of photovoltaic power generation nodes, and the set of load nodes in the system; and are respectively the branch current and resistance; ∆ t is the time interval; , are wind power and photovoltaic power generation data; 、 、 、 、 、 、 、 、 are the unit prices of network loss, main grid power purchase, wind abandonment, light abandonment, load loss penalty, OLTC regulation, CB switching, SVG operation, and BESS operation respectively; 、 、 and represent the main grid output, wind power output, photovoltaic power output, and load loss active power respectively, which are part of the decision variables corresponding to the operation layer. In addition, the decision variables also include control variables based on the equipment of the distribution network itself, such as OLTC, BESS, CB, and SVC; 、 、 、 are the OLTC regulation amount, CB switching amount, SVG regulation amount, and BESS regulation amount respectively.

[0093] In the preferred solution, in S4, the power flow constraint,

[0094] (6)

[0095] (7)

[0096] (8)

[0097] In the formula: x ij is the reactance of branch ij ; B is the set of all nodes in the system, B BESS 、 B OLTC 、 B CB and B SVC are the node sets with BESS, OLTC, CB, and SVG connected respectively; is the set of the end nodes of the branch with j as the head node; is the set of the head nodes of the branch with j as the end node; is the voltage of node j at the t th time period; 、 are the branches respectivelyij The t active power and reactive power in the time period; 、 are respectively the j charging power and discharging power of the BESS connected to node t in the time period; is the tap ratio of the OLTC connected to node i in the t time period, the ratio of the secondary side to the primary side; 、 、 are respectively the reactive power values of the wind turbine, CB, and SVG; 、 are respectively the predicted reactive power value of the load and the reactive power of the load loss.

[0098] In the preferred solution, in S4, the security constraint,

[0099] (9)

[0100] In the formula: 、 、 are respectively the upper and lower limits of the node voltage amplitude and the upper limit of the current amplitude.

[0101] In the preferred solution, in S4, the transformer node power constraint,

[0102] (10)

[0103] In the formula: 、 、 and are respectively the upper and lower limits of the active power and reactive power of the transformer.

[0104] In the preferred solution, in S4, the OLTC constraint,

[0105] (11)

[0106] In the formula: and are respectively the upper and lower limits of the adjustable tap ratio of the OLTC, is the tap ratio of the OLTC in the t time period.

[0107] In the preferred solution, in S4, the BESS operation constraints include charge and discharge constraints, power constraints, and capacity constraints;

[0108] Charge and discharge constraints;

[0109] (12)

[0110] Power constraint;

[0111] (13)

[0112] Capacity constraint;

[0113] (14)

[0114] Where: and are the charge and discharge states of the BESS respectively; 、 、 and are the upper and lower limits of the charge and discharge power of the BESS respectively; is the state of charge of the BESS at the t time period, and are the upper and lower limits considering factors such as the life of the BESS; and are the charge and discharge efficiencies respectively.

[0115] In the preferred solution, in S4, the CB operation constraint,

[0116] (15)

[0117] Where: is the number of CBs connected to node j operated during the t time period; is the upper limit of the number of CBs connected to node j ; is the compensation capacity of each CB; is the upper limit of the number of operations.

[0118] In the preferred solution, in S4, the static var compensator SVG operation constraint,

[0119] (16)

[0120] Where: and are the upper and lower limits of the SVC compensation power respectively.

[0121] In the preferred solution, in S4, the DG-related constraints and the load shedding constraints;

[0122] DG-related constraints,

[0123] (17)

[0124] The reactive power compensation ability of the DG is considered, and its reactive power compensation ability and respectively according to the maximum capacity of the DG converter and and the output power of the DG connected to the current node j during t period output and determine; and are the upper limits of PV and WT output power respectively;

[0125] Load shedding constraint,

[0126] (18)

[0127] 、 are the reactive and active powers of load shedding respectively, is the upper limit value of the active power ratio of load shedding.

[0128] It mainly includes the high-voltage construction access substation, the medium-voltage distribution network network unit, the low-voltage distribution transformers corresponding to different electrical loads, the upper reservoir area, the camp area, the lower reservoir area, some areas of the sand and gravel area, and various types of electrical loads at the end of each area.

[0129] At the same time, it includes various voltage and reactive power compensation devices such as DG, capacitor banks, SVG, and OLTC, so as to realize the economic design of the entire construction power supply system. A flexible and mobile diesel generator backup power supply is used in the construction power supply system to compensate for the energy of the entire power supply system.

[0130] The voltage and reactive power optimization of the distribution network in the construction power supply system of the pumped-storage power station is considered, the economic optimal planning of the distribution network control equipment is realized, the demand for the access of DG and the load growth in the distribution network is effectively adapted, the economy of the overall planning and operation of the distribution network is improved, and the orderly economic construction investment of the distribution network is promoted.

[0131] It solves the problems of large reactive power loss in the distribution network lines and unstable terminal voltage in the construction power supply system of the pumped-storage power station; through the analysis considering the characteristics of the construction power supply load, the reactive power and voltage of the construction power supply system are optimized in the planning and design, so as to improve the terminal voltage level and improve the power quality of the system.

[0132] The problem of hierarchical planning and optimization of distribution network voltage and reactive power has complex objectives and many constraints, and it is a multi-dimensional non-linear optimization problem. The improved particle swarm optimization (IPSO) is used to solve it.

[0133] In order to meet the needs of the construction power supply system of pumped-storage power stations for the access of distributed power sources and the growth of loads in the distribution network, a planning scheme is adopted in which the upper investment layer focuses on the planning and construction of equipment, with the goal of minimizing the total investment cost and operating cost. The lower layer is the voltage and reactive power optimization layer, which focuses on optimizing the optimal operation scheme of the distribution network, considering the operation constraints of equipment and systems, and aiming at minimizing the operation cost of the distribution network. Finally, through repeated iteration and solution by IPSO, the optimal planning scheme result of the distribution network is obtained, so as to solve the problems of large reactive power loss in the distribution network lines and unstable terminal voltage in the construction power supply system of pumped-storage power stations, improve the terminal voltage level, and improve the power quality of the system.

[0134] The above embodiments are only the preferred technical solutions of the present invention and should not be regarded as limitations on the present invention. The embodiments in this application and the features in the embodiments can be arbitrarily combined with each other without conflict. The protection scope of the present invention should be the technical solutions recorded in the claims, including the equivalent replacement solutions of the technical features in the technical solutions recorded in the claims. That is, the equivalent replacement improvements within this scope are also within the protection scope of the present invention.

Claims

1. A method for hierarchical planning of distribution network voltage and reactive power in a pumped-storage power construction power supply system, characterized in that It includes the following steps: S1, the overall model, and the objective function includes the planned investment cost C INV and the planned operating cost C OPE ; The upper-layer model makes a planning scheme with the goal of minimizing the investment cost for the siting and sizing problems of DG, capacitor banks, SVG, and OLTC equipment in the distribution network; the lower-layer model optimizes the operation variables of the distribution network with the goal of minimizing the planning operation cost based on the upper-layer decision results. The distribution network hierarchical planning model is expressed as: (1) In the formula: and are the upper and lower layer objective functions; and , and are the upper and lower layer constraint conditions; x inv and x ope are the investment decision variable and the simulation operation variable respectively; as can be seen from Equation (1), this model is a unidirectional two-layer model, that is, the upper layer model transfers state variables to the lower layer, and the variable decision of the lower layer affects the upper layer, which is reflected by adding the operation cost to the upper layer constraint; S2, objective function (2) Wherein: L ij is the length of the branch ij ; l is the equipment type identifier; 、 、 、 、 、 are the sets of candidate nodes for the corresponding investment equipment; 、 、 、 、 、 are the sets of candidate types for the corresponding investment equipment; 、 、 、 、 、 are the unit investment cost coefficients of the corresponding investment equipment; 、 、 、 、 and represent whether the corresponding investment equipment is installed or the installation quantity. This item is the decision variable corresponding to the investment layer, where is an integer variable, and the rest are all 0-1 variables, is whether to invest in the transformer tap; S3, constraint conditions S3-1, equipment type selection constraint (4) This constraint indicates that the type selections of transformers, lines, BESS, and SVG are unique, and each node can only select one model from the set of candidate types for investment. S3-2, limit on the number of installation nodes of grouped capacitors (5) In the formula is the installation quantity of CB at j the number of node installations, M CB is the limit value of the installation quantity of each node of CB; S4, operation constraints, including power flow constraints, security constraints, transformer node power constraints, OLTC constraints, BESS operation constraints, CB operation constraints, static var compensator SVG operation constraints, DG-related constraints, and load loss constraints S5, solution S5-1, with the goal of minimizing the planned investment cost, use IPSO to solve the equipment investment siting and sizing model to obtain the results related to the investment planning cost and the distribution network decision-making scheme S5-2, based on the distribution network decision-making scheme in S5-1, with the goal of minimizing the planned operation cost, use IPSO to solve the equipment investment operation cost to obtain the lower-layer optimization results, including the results related to the distribution network operation scheme and the investment operation cost S5-3, according to the results related to the distribution network operation scheme in S5-2, solve the equipment investment siting and sizing model considering the distribution network investment operation to obtain the planned cost, the upper-layer optimization results, and the total investment cost S5-4, iterative optimization of the upper and lower layers until the termination condition is met 2. The voltage and reactive power hierarchical planning method for the distribution network of the pumped-storage power generation construction power supply system according to claim 1, characterized in that: In S2, the operation cost mainly adds the costs of wind curtailment, PV curtailment, and load loss, and at the same time considers the operation costs of each active management unit OLTC, BESS, CB, and SVG in the distribution network (3) Wherein: ω is the conversion factor between the operating cost and the investment cost; E is the line set; B TR , B WTG , B PVG , B Load are respectively the sets of all transformer nodes, wind power nodes, photovoltaic power generation nodes and load nodes in the system; and are respectively the branch current and resistance; ∆ t is the time interval; , are the wind power and photovoltaic power generation data; , , , , , , , , are respectively the unit prices of network loss, main network power purchase, wind power curtailment, photovoltaic power curtailment, load shedding penalty, OLTC regulation, CB switching, SVG operation, and BESS operation; , , and respectively represent the main network output, wind power output, photovoltaic power generation output and load shedding active power, which are partial decision variables corresponding to the operation layer. In addition, the decision variables also include control variables mainly composed of OLTC, BESS, CB and SVC distribution network equipment; , , , are respectively the OLTC regulation amount, CB switching amount, SVG regulation amount and BESS regulation amount.

3. The voltage and reactive power hierarchical planning method for the distribution network of the pumped-storage power generation construction power supply system according to claim 1, characterized in that: In S4, power flow constraints (6) (7) (8) Wherein: x ij is the branch ij reactance; B is the set of all nodes in the system, B BESS , B OLTC , B CB and B SVC are the node sets connected with BESS, OLTC, CB and SVG respectively; is the set of the end nodes of the branches with j as the head nodes; is the set of the head nodes of the branches with j as the end nodes; is the voltage of node j at the t time period; , are the active power and reactive power of branch ij at the t time period respectively; , are the charging power and discharging power of the BESS connected to node j at the t time period respectively; is the transformation ratio of the OLTC connected to node i at the t time period, which is the ratio of the secondary side to the primary side; , , are the reactive power values of the wind turbine, CB and SVG respectively; , are the predicted reactive power value of the load and the reactive power of the load loss respectively.

4. The voltage and reactive power hierarchical planning method for the distribution network of the pumped-storage power generation construction power supply system according to claim 1, characterized in that: In S4, security constraints (9) Where: , , are the upper and lower limits of the node voltage amplitude and the upper limit of the current amplitude, respectively.

5. The voltage and reactive power hierarchical planning method for the distribution network of the pumped-storage power generation construction power supply system according to claim 1, characterized in that: In S4, transformer node power constraints (10) In the formula: , , and are respectively the upper and lower limits of the active power and reactive power of the transformer.

6. The voltage and reactive power hierarchical planning method for the distribution network of the pumped-storage power generation construction power supply system according to claim 1, characterized in that: In S4, OLTC constraints (11) Wherein: and are respectively the upper and lower limits of the adjustable transformation ratio of the OLTC, is the transformation ratio of the OLTC at t time period.

7. The voltage and reactive power hierarchical planning method for the distribution network of the pumped-storage power generation construction power supply system according to claim 1, characterized in that: In S4, BESS operation constraints, including charge and discharge constraints, power constraints, and capacity constraints Charge and discharge constraints (12) Power constraints (13) Capacity constraints (14) where: and are the charge and discharge states of the BESS, respectively; , , and are the upper and lower limits of the charge and discharge power of the BESS, respectively; is the state of charge of the BESS at the t th time period, and and are the upper and lower limits considering the BESS life factor; and are the charge and discharge efficiencies, respectively.

8. The voltage and reactive power hierarchical planning method for the distribution network of the pumped-storage power generation construction power supply system according to claim 1, characterized in that: In S4, CB operation constraints (15) Wherein: is the node j The number of CBs connected at the t operation period; is the node j The upper limit of the number of CBs connected; is the compensation capacity of each CB; is the upper limit of the number of operations.

9. The method for hierarchical planning of distribution network voltage and reactive power of the pumped-storage power generation construction power supply system according to claim 1, wherein: In S4, the operation constraints of the static var compensator SVG (16) Wherein: and are respectively the upper and lower limits of the SVC compensation power.

10. The method for hierarchical planning of distribution network voltage and reactive power of the pumped-storage power generation construction power supply system according to claim 1, wherein: In S4, the DG-related constraints and the load shedding constraints; DG-related constraints (17) Considering the reactive power compensation capacity of DG, its reactive power compensation capacity and are determined respectively according to the maximum capacity of the DG converter and and the output j of the DG connected to the current node t during the period; It is determined; and are the upper limits of PV and WT output respectively; Load shedding constraints (18) , are the lost load reactive power and active power respectively, is the upper limit value of the proportion of lost load active power.

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