Method for optimizing development balance degree of alternating-current and direct-current series-parallel subarea power grid

Abstract

The invention discloses a method for optimizing development balance degree of an alternating current and direct current hybrid subarea power grid, which relates to the technical field of power system planning and comprises the following steps: constructing a subarea power grid development refinement model, realizing model interconnection through alternating current and direct current coupling nodes, and forming a power grid topological structure description file comprising an admittance matrix and an equipment parameter library; carrying out controllable phase shifter configuration and scene control, constructing a controllable phase shifter model, configuring a phase shifter at a node of a partition tie line, and setting a typical scene to carry out multi-scene control; and inputting a current operation scene, calling phase shifter parameters, obtaining a phase shifter model optimization target and constraint conditions, carrying out multi-factor collaborative optimization through a direct current operation mode, a phase shifter adjustment mode and a unit operation mode, and outputting an optimized operation scheme. The method can adapt to the alternating current and direct current series-parallel partition power grid, the development requirements of all the partitions are remarkably balanced, and the partition mutual aid capacity and the large-scale benefit of the power grid are brought into play.

Description

Technical Field

[0001] The present invention relates to the technical field of power system planning, and particularly to an optimization method for the development balance degree of an AC-DC hybrid partitioned power grid. Background Art

[0002] With the large-scale grid connection of high-proportion renewable energy sources such as wind power and photovoltaic power, the power system is rapidly developing towards a high-proportion new energy direction. The strong volatility and uncertainty of new energy pose higher requirements for the real-time balancing ability of the power grid. At the same time, with the multi-DC fed power grid, multiple DC power sources are connected through the high-voltage DC transmission system, significantly improving the power cross-regional allocation ability, and the power grid forms an AC-DC hybrid pattern. However, the superposition effect of high new energy penetration and multi-DC feeding leads to the complication of the power grid power flow distribution. Traditional regulation methods based on deterministic models are difficult to adapt to bidirectional stochastic power fluctuations, exacerbating risks such as voltage instability and frequency over-limit. It is urgent to explore new operation control strategies to improve the flexibility and robustness of the power grid.

[0003] Under the background of the expansion of the scale of new energy and DC feeding, the problems of unbalanced power flow, load, and power source distribution among partitions of the power grid are becoming increasingly prominent. Some partitions face transmission channel congestion due to the concentrated access of new energy or the sharp increase in receiving-end load, while other partitions may cause resource waste due to redundant regulation capabilities. The core of optimizing the partition balance degree lies in coordinating the power interaction between regions and improving the overall operation efficiency. It is urgent to relieve the over-limit of the power flow at key sections, reduce network losses, enhance the power support ability under faults, and take into account economy and security. In addition, there are differences in the resource patterns and regulation characteristics of different partitions, such as the new energy-rich sending end area and the multi-DC landing receiving end area, and differential modeling is also required to achieve global dynamic balance.

[0004] The current mainstream optimization adjustment method based on sensitivity analysis only changes the power flow at key sections by adjusting the generator output or DC power, relying on linear assumptions, and is difficult to handle non-linear scenarios. Phase shifters can balance line loads, prevent overloads, reduce network losses, and improve system stability. However, the existing methods based on phase shifters only consider installing on a single tie line and cannot ensure the maximization of the transmission capacity under the coordinated operation of multiple tie lines, and the mutual assistance ability between partitions cannot be exerted. At the same time, a single phase shifter has little effect on the balance degree of high-voltage level main transformers, and the scale benefit of the partitioned power grid cannot be exerted. The demands of different interconnected partitions for the development direction of the power grid vary greatly.

[0005] Therefore, it is urgent to study how to adopt an optimization method based on multiple phase shifters to balance the development demands among partitions and exert the partition mutual assistance ability and the scale benefit of the power grid. Summary of the Invention

[0006] In view of the problems existing in the existing methods for optimizing the development balance degree of AC-DC hybrid partitioned power grids, the present invention is proposed. Therefore, the problem to be solved by the present invention is how to provide a method for optimizing the development balance degree of AC-DC hybrid partitioned power grids.

[0007] To solve the above technical problems, the present invention provides the following technical solutions:

[0008] In a first aspect, the present invention provides a method for optimizing the development balance degree of an AC-DC hybrid partitioned power grid, which includes constructing a refined model of the development of the partitioned power grid, realizing model interconnection through AC-DC coupling nodes, and forming a power grid topology structure description file including an admittance matrix and an equipment parameter library; the refined model of the development of the partitioned power grid includes a load model, a power source model, a DC model, a substation model, and a line model.

[0009] Conduct controllable phase shifter configuration and scenario control, construct a controllable phase shifter model, configure phase shifters at the partitioned tie-line nodes, and set typical scenarios for multi-scenario control.

[0010] Input the current operation scenario, call the phase shifter parameters, obtain the optimization objectives and constraint conditions of the phase shifter model, and conduct multi-factor collaborative optimization through the DC operation mode, the phase shifter adjustment mode, and the unit operation mode, and output the optimized operation plan.

[0011] As a preferred scheme of the method for optimizing the development balance degree of the AC-DC hybrid partitioned power grid according to the present invention, wherein: the load model includes a public transformer model and a user transformer model, and the expression of the public transformer model is:

[0012]

[0013] a p +b p +c p =1

[0014] In the formula, L P represents the constant power of the public transformer, L P0 represents the active power base value of the public transformer under the rated voltage, V P represents the actual voltage value of the public transformer node, V P0 represents the rated voltage value of the public transformer, a p , b p , c p correspond to the weight coefficients of the constant impedance, constant current, and constant power of the public transformer respectively; σ P and n respectively represent the annual growth rate of the public transformer load and the current round of power grid planning deduction year;

[0015] The expression of the user transformer model is:

[0016]

[0017] a p +b p +c p =1

[0018] In the formula, L U represents the constant power of the user transformer, L U0 represents the base value of the active power of the user transformer under the rated voltage, V U represents the actual voltage value of the user transformer node, V U0 represents the rated voltage value of the user transformer, a p 、b p 、c p correspond to the weight coefficients of the constant impedance, constant current, and constant power of the user transformer respectively, σ U and n represent the annual growth rate of the user transformer load and the year of the current round of power grid planning deduction respectively;

[0019] The power source model includes a thermal power model, a wind power model, a photovoltaic model, and an energy storage model; the expression of the thermal power model is:

[0020] G T,min ≤G T ≤G T,max ,

[0021] |G T (t + 1)-G T (t)|≤ΔG T,max ,

[0022] C(G T )=a g G T 2 +b g G T +c g .

[0023] a g +b g +c g =1

[0024] In the formula, G T,min and G T,max respectively represent the minimum and maximum active power outputs of the thermal power unit per unit time, G T is the active power output of the thermal power unit per unit time, G T (t) is the active power output of the thermal power unit per unit time at time t, G T (t + 1) is the active power output of the thermal power unit per unit time at time t + 1, ΔG T,max represents the maximum ramp power per unit time, reflecting the regulation speed of the unit; a g 、b g and cg respectively represent the marginal cost coefficient reflecting the fuel efficiency, the linear cost coefficient of the fuel, and the fixed cost;

[0025] The wind power model expression is:

[0026] G W = 0, v < v cut-in or v > v cut-out ,

[0027]

[0028] G W = P rated , v rated ≤ v ≤ v cut-out .

[0029] In the formula, G W is the wind power output, v is the wind speed, P rated represents the rated power of the wind turbine, v cut-in is the cut-in wind speed, indicating the lowest wind speed at which the wind turbine starts generating electricity; v rated is the rated wind speed, indicating the wind speed at which the wind turbine reaches its rated power; v cut-out is the cut-out wind speed, indicating the maximum wind speed at which the wind turbine shuts down for protection;

[0030] The photovoltaic model expression is:

[0031]

[0032] In the formula, G P is the photovoltaic output, P STC represents the rated power under standard test conditions, G is the actual light intensity, G STC represents the light intensity under standard test conditions, k is the temperature coefficient, T cell is the photovoltaic cell temperature, T STC represents the photovoltaic cell temperature under standard test conditions;

[0033] The energy storage model expression is:

[0034] 0 ≤ G Sch ≤ P max , 0 ≤ G Sdis ≤ P max ,

[0035]

[0036] In the formula, G Sch and G Sdis respectively represent the charging power and discharging power of the energy storage system; P max represents the maximum charge-discharge power of the energy storage system, η ch and ηdis respectively represent the charging efficiency and discharging efficiency of the energy storage system; E max is the energy storage capacity, representing the maximum energy output of the energy storage system; SOC(t) represents the state of charge of the energy storage system at time t, and SOC(t + 1) represents the state of charge of the energy storage system at time t + 1.

[0037] As a preferred embodiment of the method for optimizing the development balance degree of the AC-DC hybrid partitioned power grid according to the present invention, wherein: the DC model includes an external region DC model, an inter-region DC model, and an urban DC model; the expression of the external region DC model is:

[0038] D O = V O I O ,

[0039] P loss = a + bI O + CI O 2 .

[0040] In the formula, D O represents the external region DC power, P loss represents the power loss, V O and I O respectively represent the voltage and current of the external region DC; a is the fixed loss, b is the conduction loss coefficient, and c is the resistance loss coefficient;

[0041] The expression of the inter-region DC model is:

[0042] D P = V P I P ,

[0043] P loss = a + bI P + CI P 2 .

[0044] In the formula, D P represents the inter-region DC power, V P and I P respectively represent the voltage and current of the inter-region DC; a is the fixed loss, b is the conduction loss coefficient, and c is the resistance loss coefficient;

[0045] The expression of the urban DC model is:

[0046] D C = V C I C ,

[0047] P loss = a + bI C + CIC 2 .

[0048] In the formula, D C represents the DC power of the city, V C and I C represent the voltage and current of the city DC respectively; a

[0049] is the fixed loss, b is the conduction loss coefficient, and c is the resistance loss coefficient;

[0050] The substation model includes a 500 kV substation with a power supply capacity greater than the demand area and a 500 kV substation with a power supply capacity less than the demand area;

[0051] The model expression of the 500 kV substation with a power supply capacity greater than the demand area is:

[0052] V1 = kV2,

[0053] T S = V1I1 * = V2I2 * ,

[0054] Z tr = R tr + jX tr .

[0055] In the formula, V1 represents the voltage on the high-voltage side of the transformer, V2 represents the voltage on the low-voltage side of the transformer, k is the transformer turns ratio, representing the voltage ratio between the high-voltage side and the low-voltage side; Z tr is the short-circuit impedance of the transformer, R tr is the equivalent resistance of the transformer, and X tr is the leakage reactance of the transformer;

[0056] The model expression of the 500 kV substation with a power supply capacity less than the demand area is:

[0057] V1 = kV2,

[0058] T N = V1I1 * = V2I2 * ,

[0059] Z tr = R tr + jX tr .

[0060] In the formula, k is the transformer turns ratio, representing the voltage ratio between the high-voltage side and the low-voltage side;

[0061] The line model includes a main power flow distribution path model and a sectional tie line model; The expression of the main power flow distribution path model is:

[0062]

[0063] R F = V i 2 G ij -V i V j (G ij cosθ ij + B ij sinθ ij ).

[0064] Wherein, R and X respectively represent the resistance and reactance of the line; B is the susceptance of the line to the ground; G ij and B ij are respectively the real part and the imaginary part of the line admittance, and θ ij represents the voltage phase angle difference between nodes i and j;

[0065] The expression of the sectional tie-line model is:

[0066]

[0067] R L = V i 2 G ij -V i V j (G ij cosθ ij + B ij sinθ ij ).

[0068] Wherein, R and X respectively represent the resistance and reactance of the line; B is the susceptance of the line to the ground; G ij and B ij are respectively the real part and the imaginary part of the line admittance, and θ ij represents the voltage phase angle difference between nodes i and j.

[0069] As a preferred scheme of the method for optimizing the development balance degree of the AC-DC hybrid sectional power grid described in the present invention, wherein: the phase shifter is an ideal transformer, and the phase shifter updates the original admittance matrix of the line through the nodes on the connecting line. If the line is a pure reactance, the admittance matrix remains complex symmetric; if the line has resistance, the admittance matrix is asymmetric, indicating that the phase shifter is regarded as an active element.

[0070] As a preferred scheme of the method for optimizing the development balance degree of the AC-DC hybrid sectional power grid described in the present invention, wherein: the typical scenarios include summer noon peak, summer evening peak, winter noon peak, winter evening peak, spring and autumn low valley;

[0071] When the typical scenario is the summer noon peak scenario, the grid power flow is controlled to be 1.0 p.u. of the load, the wind power does not output, the photovoltaic power output is 0.1 p.u., the energy storage discharges 1.0 p.u., the extra-provincial DC output is 1.0 p.u., and the provincial DC output is 0.3 p.u.;

[0072] When the typical scenario is the summer evening peak scenario, the grid power flow is controlled to be 1.0 p.u. of the load, the wind power does not output, the photovoltaic power does not output, the energy storage discharges 1.0 p.u., the extra-provincial DC output is 1.0 p.u., and the provincial DC output is 1.0 p.u.;

[0073] When the typical scenario is the winter noon peak scenario, the grid power flow is controlled to be 0.9 p.u. of the load, the wind power output is 0.1 p.u., the photovoltaic power output is 0.1 p.u., the energy storage discharges 1.0 p.u., the extra-provincial DC output is 1.0 p.u., and the provincial DC output is 0.3 p.u.;

[0074] When the typical scenario is the winter evening peak scenario, the grid power flow is controlled to be 0.9 p.u. of the load, the wind power output is 0.1 p.u., the photovoltaic power does not output, the energy storage discharges 1.0 p.u., the extra-provincial DC output is 1.0 p.u., and the provincial DC output is 1.0 p.u.;

[0075] When the typical scenario is the spring and autumn low valley scenario, the grid power flow is controlled to be 0.8 p.u. of the load, the wind power does not output, the photovoltaic power does not output, the energy storage pumps electricity 1.0 p.u., the extra-provincial DC does not output, and the provincial DC output is 1.0 p.u.

[0076] As a preferred embodiment of the method for optimizing the development balance degree of the AC-DC hybrid partitioned power grid according to the present invention, wherein: the phase shifter is installed on the partition connection line, and the adjustable angle, impedance range, capacity and current of the phase shifter are set; the optimization objectives of the phase shifter model include minimizing the network active power loss, balancing the line load and minimizing the cost; the constraint conditions include the generator power balance and physical limitations.

[0077] In a second aspect, the present invention provides a computer device, including a memory and a processor, where: when the processor executes the computer program, the steps of the method for optimizing the development balance degree of the AC-DC hybrid partitioned power grid are implemented.

[0078] In a third aspect, the present invention provides a computer-readable storage medium, on which a computer program is stored, where: when the computer program is executed by a processor, the steps of the method for optimizing the development balance degree of the AC-DC hybrid partitioned power grid are implemented.

[0079] Based on the characteristics of controllable phase shifters and the power flow distribution characteristics of the power grid, the present invention proposes a control strategy that coordinates multiple factors such as DC operation mode, phase shifter adjustment mode, and unit operation mode, optimizes the development balance degree of the partitioned power grid, and improves the development demand direction of the power grid. It can be adapted to the AC-DC hybrid partitioned power grid, significantly balance the development demands among different partitions, and give play to the partition mutual assistance ability and the scale benefit of the power grid. BRIEF DESCRIPTION OF THE DRAWINGS

[0080] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0081] Figure 1 It is a refined model diagram for the development of an AC-DC hybrid partitioned power grid in a power system.

[0082] Figure 2 It is a simulated development model diagram for the AC-DC hybrid partitioned power grid in a power system. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0083] In order to make the above objects, features, and advantages of the present invention more understandable, the following will make a detailed description of the specific embodiments of the present invention with reference to the accompanying drawings of the specification. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of them. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the scope of protection of the present invention.

[0084] In the following description, many specific details are set forth in order to fully understand the present invention. However, the present invention can also be implemented in other ways different from those described herein. Those skilled in the art can make similar extensions without departing from the connotation of the present invention. Therefore, the present invention is not limited by the specific embodiments disclosed below.

[0085] Secondly, the so-called "one embodiment" or "embodiment" herein refers to a specific feature, structure, or characteristic that can be included in at least one implementation manner of the present invention. The "in one embodiment" that appears in different places in this specification does not necessarily refer to the same embodiment, nor is it an embodiment that is separately or selectively mutually exclusive with other embodiments.

[0086] Referring to Figure 1 and Figure 2 , it is the first embodiment of the present invention. This embodiment provides a method for optimizing the development balance degree of an AC-DC hybrid partitioned power grid, including:

[0087] S1: Construct a refined model for the development of a regional power grid, interconnect the models through AC / DC coupling nodes, and form a grid topology description file containing an admittance matrix and a device parameter library;

[0088] The refined model of regional power grid development includes load model, power supply model, DC model, substation model and line model;

[0089] Specifically, the refined model for regional power grid development includes load model, power supply model, DC model, substation model and line model.

[0090] The load model includes the public transformer model and the user transformer model. The public transformer model is expressed as:

[0091]

[0092] a p +b p +c p =1

[0093] Where, L P Indicates common variable constant power, L P0 Indicates the active power base value of the utility transformer at rated voltage, V P Indicates the actual voltage value of the common transformer node, V P0 Indicates the rated voltage of the public transformer, a p , b p 、c p The weight coefficients corresponding to the constant impedance, constant current and constant power of the common transformer respectively; σ P and n represent the annual growth rate of utility variable load and the year of this round of power grid planning deduction respectively;

[0094] The user variable model expression is:

[0095]

[0096] a p +b p +c p =1

[0097] Where, L U Indicates that the user changes the constant power, L U0 Indicates the active power base value of the user transformer under rated voltage, V U Indicates the actual voltage value of the user node, V U0 Indicates the rated voltage value of the user transformer, a p , b p 、c p The weight coefficients corresponding to the user's constant impedance, constant current, and constant power, σ Um and n represent the annual growth rate of user load variation and the year of this round of power grid planning deduction respectively;

[0098] The power source model includes a thermal power model, a wind power model, a photovoltaic model, and an energy storage model; the expression of the thermal power model is:

[0099] G T,min ≤G T ≤G T,max ,

[0100] |G T (t + 1) - G T (t)| ≤ ΔG T,max ,

[0101] C(G T ) = a g G T 2 + b g G T + c g .

[0102] a g + b g + c g = 1

[0103] In the formula, G T,min and G T,max respectively represent the minimum and maximum active power outputs of the thermal power unit per unit time, G T is the active power output of the thermal power unit per unit time, G T (t) is the active power output of the thermal power unit per unit time at time t, G T (t + 1) is the active power output of the thermal power unit per unit time at time t + 1, ΔG T,max represents the maximum ramp rate per unit time, reflecting the regulation speed of the unit; a g , b g and c g respectively represent the marginal cost coefficient reflecting fuel efficiency, the linear cost coefficient of fuel, and the fixed cost (such as maintenance cost);

[0104] The expression of the wind power model is:

[0105] G W = 0, v < v cut-in or v > v cut-out ,

[0106]

[0107] G W = P rated , v rated ≤ v ≤ v cut-out .

[0108] Wherein, G W is the wind power output, v is the wind speed, and P rated represents the rated power of the wind turbine. v cut-in is the cut-in wind speed, which represents the lowest wind speed at which the wind turbine starts generating electricity; v rated is the rated wind speed, which represents the wind speed at which the wind turbine reaches its rated power; v cut-out is the cut-out wind speed, which represents the maximum wind speed at which the wind turbine shuts down for protection;

[0109] The photovoltaic model expression is:

[0110]

[0111] Wherein, G P is the photovoltaic power output, and P STC represents the rated power under standard test conditions. G is the actual light intensity, and G STC represents the light intensity under standard test conditions. k is the temperature coefficient, usually negative, indicating that the output power decreases when the temperature rises; T cell is the temperature of the photovoltaic cell, and T STC represents the temperature of the photovoltaic cell under standard test conditions; STC refers to the light intensity G STC = 1000 W / m 2 and the temperature T STC = 25 °C.

[0112] The energy storage model expression is:

[0113] 0 ≤ G Sch ≤ P max , 0 ≤ G Sdis ≤ P max ,

[0114]

[0115] Wherein, G Sch and G Sdis respectively represent the charging power and discharging power of the energy storage system; P max represents the maximum charging and discharging power of the energy storage system, η ch and η dis respectively represent the charging efficiency and discharging efficiency of the energy storage system; E max is the energy storage capacity, which represents the maximum output energy of the energy storage system; SOC(t) represents the state of charge of the energy storage system at time t, and SOC(t + 1) represents the state of charge of the energy storage system at time t + 1, with a range between 0 and 1.

[0116] The DC model includes an external DC model, an inter-regional DC model, and an urban DC model. The expression of the external DC model is:

[0117] D O = V O I O ,

[0118] P loss = a + bI O + cI O 2 .

[0119] In the formula, D O represents the DC power outside the area, and P loss represents the power loss, V O and I O respectively represent the voltage and current of the DC outside the area; a is the fixed loss, b is the conduction loss coefficient, and c is the resistance loss coefficient;

[0120] The expression of the cross - area DC model is:

[0121] D P = V P I P ,

[0122] P loss = a + bI P + cI P 2 .

[0123] In the formula, D P represents the cross - area DC power, V P and I P respectively represent the voltage and current of the cross - area DC; a is the fixed loss, b is the conduction loss coefficient, and c is the resistance loss coefficient;

[0124] The expression of the urban DC model is:

[0125] D C = V C I C ,

[0126] P loss = a + bI C + cI C 2 .

[0127] In the formula, D C represents the urban DC power, V C and I C respectively represent the voltage and current of the urban DC; a is the fixed loss, b is the conduction loss coefficient, and c is the resistance loss coefficient;

[0128] The substation model includes 500 kV substations with power supply capacity greater than that of the demand zone and 500 kV substations with power supply capacity less than that of the demand zone; the model expression of the 500 kV substation with power supply capacity greater than that of the demand zone is:

[0129] V1 = kV2,

[0130] T S = V1I1 * = V2I2 * ,

[0131] Z tr = R tr + jX tr .

[0132] In the formula, V1 represents the voltage on the high - voltage side of the transformer, and V2 represents the voltage on the low - voltage side of the transformer,

[0133] k is the transformation ratio of the transformer, representing the voltage ratio between the high - voltage side and the low - voltage side; Z tr is the short - circuit impedance of the transformer, R tr is the equivalent resistance of the transformer, X tr is the leakage reactance of the transformer; the model expression of the 500 kV substation with power supply capacity less than that of the demand zone is:

[0134] V1 = kV2,

[0135] T N = V1I1 * = V2I2 * ,

[0136] Z tr = R tr + jX tr .

[0137] In the formula, k is the transformation ratio of the transformer, representing the voltage ratio between the high - voltage side and the low - voltage side.

[0138] The line model includes the main power flow distribution path and the sectional tie line.

[0139] The model expression of the main power flow distribution path is:

[0140]

[0141] R F = V i 2 G ij - V i V j (G ij cosθ ij + B ij sinθ ij .

[0142] Wherein, R and X respectively represent the resistance and reactance of the line, which are determined by the conductor material and the line length; B is the susceptance of the line to the ground, which is caused by the capacitance effect of the line; G ij and B ij are respectively the real part (conductance) and the imaginary part (susceptance) of the line admittance, and θ ij represents the voltage phase angle difference between nodes i and j.

[0143] The expression of the sectional tie-line model is:

[0144]

[0145] R L = V i 2 G ij - V i V j (G ij cosθ ij + B ij sinθ ij ).

[0146] Wherein, R and X respectively represent the resistance and reactance of the line, which are determined by the conductor material and the line length; B is the susceptance of the line to the ground, which is caused by the capacitance effect of the line; G ij and B ij are respectively the real part (conductance) and the imaginary part (susceptance) of the line admittance, and θ ij represents the voltage phase angle difference between nodes i and j.

[0147] S2: Configure the controllable phase shifter and conduct scenario control, construct the controllable phase shifter model, configure the phase shifter at the sectional tie-line node, and set typical scenarios for multi-scenario control;

[0148] Specifically, the phase shifter model can be regarded as an ideal transformer, and its complex turns ratio is, where φ is the phase shift angle. This turns ratio only changes the voltage phase and does not change the amplitude. Suppose the phase shifter is connected to nodes i and j, and the original line admittance is Y = G + jB, then its contribution to the admittance matrix is:

[0149] Self-admittance: The self-admittance from node i to j increases by Y each.

[0150] Mutual admittance: The mutual admittance from node i to j is Y ij = -Ye -jφ , and the mutual admittance from node j to i is Y ji = -Ye jφ .

[0151] Therefore, the update formula of the admittance matrix is:

[0152] Y ii←Y ii +Y,

[0153] Y jj ←Y jj +Y,

[0154] Y ij ←Y ij -Ye -jφ ,

[0155] Y ji ←Y ji -Ye jφ .

[0156] The phase shifter affects the power flow by changing the equivalent phase difference between nodes. Considering the node voltages V i =V i ∠θ i and V j =V j ∠θ j , the complex powers S ij and S ji are:

[0157] S ij =V i (Ye -jφ (V i -V j e jφ )) * ,

[0158] S ji =V j (Ye jφ (V j -V i e -jφ )) * .

[0159] After expansion, the expressions for the active power P ij and the reactive power Q ij are:

[0160] P ij =V i V j [Gcos(θ i -θ j -φ)+Bsin(θ i -θ j -φ)]-GV i 2 ,

[0161] Q ij =V i V j [Gsin(θ i-θ j -φ)-Bcos(θ i -θ j -φ)]+BV i 2 .

[0162] If the line is purely reactive (G = 0), then Y = jB, and in this case Y ji = Y ij * , and the admittance matrix remains complex symmetric.

[0163] If the line has resistance (G ≠ 0), then Y ji ≠ Y ij * , and the admittance matrix is asymmetric, indicating that the phase shifter needs to be regarded as an active component.

[0164] Typical scenarios include summer noon peak, summer evening peak, winter noon peak, winter evening peak, spring and autumn valleys;

[0165] When the typical scenario is the summer noon peak scenario, the grid power flow is controlled to be 1.0 p.u. of load, the wind power does not output, the photovoltaic output is 0.1 p.u., the energy storage discharges 1.0 p.u., the extra-provincial DC output is 1.0 p.u., and the provincial DC output is 0.3 p.u.;

[0166] When the typical scenario is the summer evening peak scenario, the grid power flow is controlled to be 1.0 p.u. of load, the wind power does not output, the photovoltaic does not output, the energy storage discharges 1.0 p.u., the extra-provincial DC output is 1.0 p.u., and the provincial DC output is 1.0 p.u.;

[0167] When the typical scenario is the winter noon peak scenario, the grid power flow is controlled to be 0.9 p.u. of load, the wind power output is 0.1 p.u., the photovoltaic output is 0.1 p.u., the energy storage discharges 1.0 p.u., the extra-provincial DC output is 1.0 p.u., and the provincial DC output is 0.3 p.u.;

[0168] When the typical scenario is the winter evening peak scenario, the grid power flow is controlled to be 0.9 p.u. of load, the wind power output is 0.1 p.u., the photovoltaic does not output, the energy storage discharges 1.0 p.u., the extra-provincial DC output is 1.0 p.u., and the provincial DC output is 1.0 p.u.;

[0169] When the typical scenario is the spring and autumn valley scenario, the grid power flow is controlled to be 0.8 p.u. of load, the wind power does not output, the photovoltaic does not output, the energy storage pumps 1.0 p.u., the extra-provincial DC does not output, and the provincial DC output is 1.0 p.u.

[0170] S3: Input the current operating scenario, call the phase shifter parameters, obtain the optimization objectives and constraints of the phase shifter model, and perform multi-factor collaborative optimization through the DC operation mode, phase shifter adjustment mode, and unit operation mode, and output the optimized operation plan.

[0171] Calculate parameters reflecting the grid development balance, such as the transmission capacity of the grid tie line and the balance degree of the main transformers in the sub-region, to reflect the optimization effect of the present invention;

[0172] Specifically, the phase shift angle is used as a control variable and can be adjusted in the optimal power flow or static security analysis to achieve the following objectives: balance the line load, prevent overload, reduce network losses, and improve system stability.

[0173] The phase shifter is installed on the sub-region tie line, and the adjustable angle, impedance range, capacity, and current of the phase shifter are set; the adjustable angle of the installed phase shifter is 20° to 20°, the impedance range is 14Ω to 20Ω, the capacity is 260MVA, and the current is 2500A.

[0174] The optimization objectives of the phase shifter model include minimizing network active power losses, balancing line loads, and minimizing costs; the constraints include generator power balance and physical limitations;

[0175] The expression for minimizing network active power losses is:

[0176]

[0177] In the formula, P loss,ij is the loss of the active power of the line, G ij represents the conductance of the line, characterizing the resistance loss of the line; V i and V j respectively represent the voltage amplitudes of nodes i and j; θ i and θ j respectively represent the voltage phase angles of nodes i and j.

[0178] The expression for balancing the line load is:

[0179]

[0180] In the formula, P ij is the actual active power of the line, obtained through power flow calculation; is the maximum allowable transmission power of the line, determined by the thermal stability limit of the line.

[0181] The expression for minimizing costs is:

[0182]

[0183] In the formula, C k (P ST) is the cost function of the phase shifter, usually a quadratic function; λ is the weight coefficient used to balance the equipment cost and the loss cost.

[0184] The constraint conditions include the generator power balance and physical limitations; the generator power balance satisfies the active and reactive power balance, and the expression is:

[0185]

[0186] Q Gi -Q Di =∑ j V i V j [G ij sin(θ i -θ j -φ)-B ij cos(θ i -θ j -φ)].

[0187] In the formula, P Gi and Q Gi are the active and reactive power outputs of the generator respectively; B ij is the susceptance of the line, which is determined by the reactance of the line.

[0188] The expression of the physical limitation is:

[0189] φ min ≤φ≤φ max ,

[0190] V i min ≤V i ≤V i max ,

[0191]

[0192] In the formula, φ, V i 、P ij 、P Gk respectively represent the range of the phase angle of the phase shifter, the node voltage amplitude, the line power capacity, and the generator output limitation.

[0193] According to the above optimization objectives, multiple phase shifters are configured in a certain simulated power grid, and the output of thermal power units and the output of urban direct current are finely adjusted. Through the simulation of the software PSDBPA, the following results are obtained: After configuring a phase shifter on a sectional tie line, the inter-sectional power transmission capacity is increased by 59%, and the balance degree of the sectional main transformer is increased by 34%; after configuring multiple phase shifters on each sectional tie line, the inter-sectional power transmission capacity is increased by 114%, the balance degree of the sectional main transformer is increased by 62%, and the balance degree of the power grid development is significantly optimized.

[0194] This embodiment also provides a computer device, which is applicable to the situation of the optimization method for the development balance degree of an AC / DC hybrid partitioned power grid, and includes: a memory and a processor; the memory is used to store computer-executable instructions, and the processor is used to execute the computer-executable instructions to implement all or part of the steps of the method described in the embodiments of the present invention as proposed in the above embodiments.

[0195] This embodiment also provides a storage medium, on which a computer program is stored. When the computer program is executed by a processor, it executes the method in any optional implementation manner of the above embodiments. Among them, the storage medium can be implemented by any type of volatile or non-volatile storage device or a combination thereof, such as static random access memory (abbreviated as SRAM), electrically erasable programmable read-only memory (abbreviated as EEPROM), erasable programmable read-only memory (abbreviated as EPROM), programmable read-only memory (abbreviated as PROM), read-only memory (abbreviated as ROM), magnetic memory, flash memory, a magnetic disk or an optical disc.

[0196] The storage medium proposed in this embodiment and the data storage method proposed in the above embodiments belong to the same inventive concept. For technical details not described in detail in this embodiment, reference can be made to the above embodiments, and this embodiment has the same beneficial effects as the above embodiments.

[0197] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the spirit and scope of the technical solutions of the present invention, and they should all be covered within the scope of the claims of the present invention.

Claims

1. An optimization method for the development balance degree of an AC / DC hybrid partitioned power grid, characterized in that: including Construct a refined model for the development of the regional power grid, interconnect the models through AC-DC coupling nodes, and form a power grid topology description file containing the admittance matrix and equipment parameter library; The refined model for the development of the regional power grid includes a load model, a power source model, a DC model, a substation model, and a line model; Configure the controllable phase shifter and perform scenario control, construct a controllable phase shifter model, configure the phase shifter at the regional tie-line node, and set typical scenarios for multi-scenario control; Input the current operating scenario, call the phase shifter parameters, obtain the optimization objectives and constraints of the phase shifter model, and perform multi-factor collaborative optimization through the DC operation mode, phase shifter adjustment mode, and unit operation mode, and output the optimized operation plan.

2. The method for optimizing the development balance degree of the AC / DC hybrid partitioned power grid according to claim 1, wherein: The load model includes a public transformer model and a user transformer model. The expression of the public transformer model is: a p +b p +c p =1 Where, L P represents the constant power of the public transformer, and L P0 represents the base value of the active power of the public transformer under the rated voltage. V P represents the actual voltage value of the public transformer node, and V P0 represents the rated voltage value of the public transformer. a p , b p , c p correspond to the weight coefficients of the constant impedance, constant current, and constant power of the public transformer respectively; σ P and n represent the annual growth rate of the public transformer load and the current round of power grid planning deduction year respectively; The expression of the user transformer model is: a p +b p +c p =1 Where, L U represents the user's constant power, L U0 represents the base value of the active power of the user transformer under the rated voltage, V U represents the actual voltage value of the user transformer node, V U0 represents the rated voltage value of the user transformer, a p , b p , c p respectively correspond to the weight coefficients of the constant impedance, constant current, and constant power of the user transformer, σ U and n respectively represent the annual growth rate of the user transformer load and the current round of power grid planning deduction year; The power source model includes a thermal power model, a wind power model, a photovoltaic model, and an energy storage model. The expression of the thermal power model is: G T,min ≤G T ≤G T,max , |G T (t + 1)-G T (t)| ≤ ΔG T,max , C(G T ) = a g G T 2 + b g G T + c g . a g +b g +c g =1 where, G T,min and G T,max respectively represent the minimum and maximum active power outputs of the thermal power unit per unit time, G T is the active power output of the thermal power unit per unit time, G T (t) is the active power output of the thermal power unit per unit time at time t, G T (t + 1) is the active power output of the thermal power unit per unit time at time t + 1, ΔG T,max represents the maximum ramp rate per unit time, reflecting the unit regulation speed; a g , b p and c g respectively represent the marginal cost coefficient reflecting fuel efficiency, the linear cost coefficient of fuel, and the fixed cost; The expression of the wind power model is: G W = 0, v < v cut-in or v > v cut-out , G W = P rated , v rated ≤ v ≤ v cut-out . Where, G W is the wind power output, v is the wind speed, and P rated represents the rated power of the wind turbine. v cut-in is the cut-in wind speed, which represents the lowest wind speed at which the wind turbine starts generating electricity; v rated is the rated wind speed, which represents the wind speed at which the wind turbine reaches its rated power; v cut-out is the cut-out wind speed, which represents the maximum wind speed at which the wind turbine shuts down for protection; The expression of the photovoltaic model is: Where, G P is the photovoltaic output, P STC represents the rated power under standard test conditions, G is the actual light intensity, G STC represents the light intensity under standard test conditions, k is the temperature coefficient, T cell is the temperature of the photovoltaic cell, T STC represents the temperature of the photovoltaic cell under standard test conditions; The expression of the energy storage model is: 0 ≤ G Sch ≤ P max , 0 ≤ G Sdis ≤ P max , Wherein, G Sch and G Sdis respectively represent the charging power and discharging power of the energy storage system; P max represents the maximum charge-discharge power of the energy storage system, η ch and η dis respectively represent the charging efficiency and discharging efficiency of the energy storage system; E max is the energy storage capacity, representing the maximum discharge energy of the energy storage system; SOC(t) represents the state of charge of the energy storage system at time t, and SOC(t + 1) represents the state of charge of the energy storage system at time t + 1.

3. The method for optimizing the development balance degree of the AC / DC hybrid partitioned power grid according to claim 2, wherein: The DC model includes an external DC model, an inter-regional DC model, and an urban DC model. The expression of the external DC model is: D O = V O I O , P loss = a + bI O + CI O 2 . where D O represents the off-region DC power, P loss represents the power loss, V O and I O respectively represent the voltage and current of the off-region DC; a is the fixed loss, b is the conduction loss coefficient, and c is the resistance loss coefficient; The expression of the inter-regional DC model is: D P = V P I P , P loss = a + bI P + CI P 2 . Where D P represents the cross-region DC power, V P and I P represent the voltage and current of the cross-region DC respectively; a is the fixed loss, b is the conduction loss coefficient, and c is the resistance loss coefficient; The expression of the urban DC model is: D C = V C I C , P loss = a + bI C + CI C 2 . where D C represents the DC power of the city, V C and I C represent the voltage and current of the city DC respectively; a is the fixed loss, b is the conduction loss coefficient, and c is the resistance loss coefficient; The substation model includes a 500 kV substation with a power supply capacity greater than the demand area and a 500 kV substation with a power supply capacity less than the demand area; The expression of the 500 kV substation model with a power supply capacity greater than the demand area is: V1 = kV2, T S = V1I1 * = V2I2 * , Z tr = R tr + jX tr . Wherein, V1 represents the voltage on the high-voltage side of the transformer, V2 represents the voltage on the low-voltage side of the transformer, k is the transformer turns ratio, representing the voltage ratio between the high-voltage side and the low-voltage side; Z tr is the short-circuit impedance of the transformer, R tr is the equivalent resistance of the transformer, X tr is the leakage reactance of the transformer; The expression of the 500 kV substation model with a power supply capacity less than the demand area is: V1 = kV2, T N = V1I1 * = V2I2 * , Z tr = R tr + jX tr . where k is the transformer turns ratio, representing the voltage ratio between the high-voltage side and the low-voltage side; The line model includes a model of the main power flow distribution path and a regional tie-line model. The expression of the model of the main power flow distribution path is: R F = V i 2 G ij -V i V j (G ij cosθ ij + B ij sinθ ij ). wherein, R and X respectively represent the resistance and reactance of the line; B is the susceptance of the line to the ground; G ij and B ij are respectively the real part and the imaginary part of the line admittance, and θ ij represents the voltage phase angle difference between nodes i and j; The expression of the regional tie-line model is: R L = V i 2 G ij -V i V j (G ij cosθ ij + B ij sinθ ij ). wherein, R and X respectively represent the resistance and reactance of the line; B is the susceptance of the line to the ground; G ij and B ij are respectively the real part and the imaginary part of the line admittance, and θ ij represents the voltage phase angle difference between nodes i and j.

4. The method for optimizing the development balance degree of an AC / DC hybrid partitioned power grid according to claim 3, wherein: The phase shifter is an ideal transformer. The phase shifter updates the original admittance matrix of the line through the nodes on the connected line. If the line is a pure reactance, the admittance matrix remains complex symmetric; if the line has resistance, the admittance matrix is asymmetric, indicating that the phase shifter is regarded as an active component.

5. The method for optimizing the development balance degree of the AC / DC hybrid partitioned power grid according to claim 4, wherein: The typical scenarios include summer noon peak, summer evening peak, winter noon peak, winter evening peak, and spring and autumn low valley; When the typical scenario is the summer noon peak scenario, then control the power grid power flow to be 1.0 p.u. of the load, the wind power does not output, the photovoltaic output is 0.1 p.u., the energy storage discharges 1.0 p.u., the external DC output is 1.0 p.u., and the provincial DC output is 0.3 p.u.; When the typical scenario is the summer evening peak scenario, then control the power grid power flow to be 1.0 p.u. of the load, the wind power does not output, the photovoltaic does not output, the energy storage discharges 1.0 p.u., the external DC output is 1.0 p.u., and the provincial DC output is 1.0 p.u.; When the typical scenario is the winter noon peak scenario, then control the power grid power flow to be 0.9 p.u. of the load, the wind power output is 0.1 p.u., the photovoltaic output is 0.1 p.u., the energy storage discharges 1.0 p.u., the external DC output is 1.0 p.u., and the provincial DC output is 0.3 p.u.; When the typical scenario is the winter peak scenario, the power grid flow is controlled as follows: load 0.9 p.u., wind power output 0.1 p.u., PV power output is zero, energy storage discharges 1.0 p.u., DC power output from outside the province is 1.0 p.u., and DC power output within the province is 1.0 p.u. When the typical scenario is the spring and autumn low valley scenario, the power grid flow is controlled as follows: load 0.8 p.u., wind power output is zero, PV power output is zero, energy storage pumps 1.0 p.u., DC power output from outside the province is zero, and DC power output within the province is 1.0 p.u.

6. The method for optimizing the development balance degree of the AC / DC hybrid partitioned power grid according to claim 5, wherein: The phase shifter is installed on the sectionalizing tie line, and the adjustable angle, impedance range, capacity, and current of the phase shifter are set. The optimization objectives of the phase shifter model include minimizing network active power loss, balancing line loads, and minimizing costs. The constraint conditions include generator power balance and physical limitations.

7. A computer device, comprising a memory and a processor, the memory storing a computer program, characterized in that: When the processor executes the computer program, it implements the steps of the method for optimizing the development balance degree of the AC-DC hybrid sectionalized power grid according to any one of claims 1 to 6.

8. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by the processor, it implements the steps of the method for optimizing the development balance degree of the AC-DC hybrid sectionalized power grid according to any one of claims 1 to 6.

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