Flexible interconnected power distribution network planning method and system considering and generating electric energy quality problem treatment

Abstract

The invention discloses a flexible interconnection power distribution network planning method and system considering and generating electric energy quality problem treatment. The method comprises the steps that according to a target power distribution network area topological structure, a target power distribution network area electric energy quality transfer constraint containing a flexible interconnection device is established; establishing a flexible interconnected power distribution network planning model considering and generating power quality problem treatment based on the target power distribution network area power quality transfer constraint; and solving the flexible interconnected power distribution network planning model considering and solving the power energy quality problem in combination with a genetic algorithm containing an elitism strategy and a second-order cone to obtain a planning strategy, and establishing a simulation model to verify the regulation and control effect of the solved flexible interconnected power distribution network planning strategy considering and solving the power energy quality problem. The flexible interconnected power distribution network planning method and system considering and generating power quality problem treatment provided by the invention not only have theoretical innovativeness and advancement, but also have wide prospects and important significance in practical application.

Description

Technical Field

[0001] The present invention relates to the technical field of flexible interconnected distribution network planning, and in particular to a flexible interconnected distribution network planning method and system that takes into account and manages power quality issues. Background Art

[0002] In recent years, with the large-scale access of distributed renewable energy to medium and low voltage distribution networks, the traditional radial AC distribution network has problems such as insufficient new energy access capacity and insufficient power dispatching capacity, which has caused great difficulties for photovoltaic consumption. On the other hand, due to the long-term problems of long lines and aging equipment in low-voltage distribution networks, especially rural distribution networks, power quality problems such as voltage over-limit, three-phase imbalance, heavy overload, harmonics, and voltage sag have long existed. The difficulty in photovoltaic consumption and the weak distribution network structure itself have led to the characteristics of concurrent, coupled, complex causes, and difficult governance of power quality problems in low-voltage distribution areas.

[0003] In response to the above problems, the capacity of traditional AC distribution networks is insufficient. On the one hand, the AC distribution network is limited by the radial topology of "closed-loop design, open-loop operation", and the power dispatching capacity is insufficient. When the source and load power do not match during photovoltaic power generation, a large amount of power will be returned, which will lead to voltage limit, imbalance and reverse overload of transformers. In order to enhance the power dispatching capacity of the distribution network, as the application scenarios of power electronics technology in new power systems continue to expand, various new rectifier inverters such as voltage source inverters are constantly being used, and establishing a flexible interconnected distribution network topology through back-to-back converters has become an industry development trend. Compared with traditional low-voltage AC distribution networks, flexible interconnected distribution networks can break the radial restrictions, have more flexible regulation, and are convenient for new source and load access. They can also solve concurrent power quality problems through power dispatching, dynamic reactive power compensation and other methods.

[0004] There are still some deficiencies in the existing research on flexible interconnected distribution network planning: on the one hand, the existing power system planning has little research on concurrent power quality issues, especially short-time scale issues such as voltage sag, which are difficult to characterize in the model; on the other hand, most of the existing research focuses on one or two power quality issues, and there is a lack of research on concurrent and coupled issues from the planning level. Summary of the invention

[0005] The purpose of this section is to summarize some aspects of embodiments of the present invention and briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this section and the specification abstract and the invention title of this application to avoid blurring the purpose of this section, the specification abstract and the invention title, and such simplifications or omissions cannot be used to limit the scope of the present invention.

[0006] In view of the above existing problems, the present invention is proposed.

[0007] Therefore, the present invention provides a flexible interconnected distribution network planning method and system that takes into account and manages power quality issues, which can solve the problems mentioned in the background technology.

[0008] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0009] In a first aspect, the present invention provides a flexible interconnected distribution network planning method that takes into account and manages power quality issues, including:

[0010] According to the topological structure of the target distribution network area, the power quality transfer constraints of the target distribution network area with flexible interconnection devices are established;

[0011] Based on the power quality transfer constraints of the target distribution network area, a flexible interconnected distribution network planning model that takes into account power quality problem management is established;

[0012] The flexible interconnected distribution network planning model that takes into account and manages power quality issues is a two-layer planning model, including an upper model and a lower model;

[0013] The flexible interconnected distribution network planning model considering the management of parallel power quality issues is solved by combining a genetic algorithm with an elite retention strategy and a second-order cone, and a flexible interconnected distribution network planning strategy considering the management of parallel power quality issues is obtained. A simulation model is established to verify the regulatory effect of the solved flexible interconnected distribution network planning strategy considering the management of parallel power quality issues.

[0014] As a preferred solution of the flexible interconnected distribution network planning method considering and managing power quality issues described in the present invention, wherein: the upper model includes: a first objective function and a first constraint condition;

[0015] The first objective function includes construction cost and operation cost;

[0016] The first constraint includes setting a cost cap.

[0017] As a preferred solution of the flexible interconnected distribution network planning method considering and managing power quality issues described in the present invention, wherein: the lower model includes: a second objective function and a second constraint condition;

[0018] The second objective function is to minimize the sum of the total amount of photovoltaic daily cutting and the total daily network loss in the low-voltage AC / DC hybrid distribution network;

[0019] The second constraint conditions include power flow constraint, node voltage constraint, three-phase imbalance constraint, transformer heavy overload constraint and flexible interconnection device related operation constraints.

[0020] As a preferred solution of the flexible interconnected distribution network planning method considering concurrent power quality problem management described in the present invention, wherein: the combination of the genetic algorithm with the elite retention strategy and the second-order cone to solve the flexible interconnected distribution network planning model considering concurrent power quality problem management includes:

[0021] The upper model in the flexible interconnected distribution network planning model that takes into account and manages power quality issues is solved by combining a genetic algorithm with an elite retention strategy;

[0022] The lower model in the flexible interconnected distribution network planning model that takes into account and manages power quality issues is solved by combining the second-order cone.

[0023] As a preferred solution of the flexible interconnected distribution network planning method considering and managing power quality issues described in the present invention, the first objective function is expressed as:

[0024]

[0025] Among them, C build is the construction cost, including the civil engineering cost of equipment C basic , the cost brought by equipment capacity, that is, the unit capacity cost C power With capacity S VSC The product of the cost of the new line at the important load port, that is, the cost per unit length of the line C line and the total line length ∑d line The product of operation is the operating cost, which is fed back by the lower model.

[0026] As a preferred solution of the flexible interconnected distribution network planning method considering and managing power quality issues described in the present invention, the second objective function is expressed as:

[0027] minF=f1ΔP PV +f2P loss

[0028] Among them, ΔP PV Represents the amount of photovoltaic cutting machine; P loss Represents the total network loss; f1 and f2 are weights. When setting, please note that the sum of the weights is 1.

[0029] As a preferred solution of the flexible interconnected distribution network planning method considering and managing power quality issues described in the present invention, the second objective function also includes:

[0030]

[0031] Among them, Φ represents the set of three phases; N ACPVrepresents the set of nodes in the low-voltage AC distribution network; v(i) represents the node directly connected to node i; represents the phase, i.e., phase A, phase B, or phase C; Tmax represents the time node number, i.e., 24 hours; and They represent the branch between node i and node j in the AC distribution network. The resistance and current of each phase at time t; and They represent the amount of photovoltaic power generation and the amount connected to the grid in the AC distribution network respectively.

[0032] In a second aspect, the present invention provides a flexible interconnected distribution network planning system that takes into account and manages power quality issues, including:

[0033] A structural analysis module is used to establish power quality transfer constraints of the target distribution network area including flexible interconnection devices according to the topological structure of the target distribution network area;

[0034] A model building module, used to establish a flexible interconnected distribution network planning model that takes into account power quality problem management based on the power quality transfer constraints of the target distribution network area;

[0035] The flexible interconnected distribution network planning model that takes into account and manages power quality issues is a two-layer planning model, including an upper model and a lower model;

[0036] The model solving module is used to solve the flexible interconnected distribution network planning model considering the management of parallel power quality problems by combining a genetic algorithm with an elite retention strategy and a second-order cone, obtain a flexible interconnected distribution network planning strategy considering the management of parallel power quality problems, and establish a simulation model to verify the regulatory effect of the solved flexible interconnected distribution network planning strategy considering the management of parallel power quality problems.

[0037] In a third aspect, the present invention provides a computer device, comprising a memory and a processor, wherein the memory stores a computer program, and the processor implements the steps of the above-mentioned method when executing the computer program.

[0038] In a fourth aspect, the present invention provides a computer-readable storage medium having a computer program stored thereon, wherein the computer program implements the steps of the method described above when executed by a processor.

[0039] Compared with the prior art, the beneficial effects of the present invention are as follows: the present invention proposes a flexible interconnected distribution network planning method and system considering the management of parallel power quality problems. According to the topological structure of the target distribution network area, the target distribution network area power quality transfer constraints containing flexible interconnected devices are established; based on the target distribution network area power quality transfer constraints, a flexible interconnected distribution network planning model considering the management of parallel power quality problems is established; the flexible interconnected distribution network planning model considering the management of parallel power quality problems is a two-layer planning model, including an upper model and a lower model; the flexible interconnected distribution network planning model considering the management of parallel power quality problems is solved by combining a genetic algorithm containing an elite retention strategy and a second-order cone to obtain a flexible interconnected distribution network planning strategy considering the management of parallel power quality problems, and establish a simulation model to verify the control effect of the solved flexible interconnected distribution network planning strategy considering the management of parallel power quality problems. Specifically, when solving the upper model, the genetic algorithm gradually optimizes the model parameters by simulating the steps of selection, crossover and mutation in the biological evolution process, with the goal of minimizing construction costs and operating costs. At the same time, the elite retention strategy ensures that the optimal solution in each generation will not be destroyed, thereby improving the stability and convergence speed of the algorithm. For the solution of the lower model, the second-order cone programming method is adopted to deal with the nonlinear constraints and complex objective functions that may exist in the model. Second-order cone programming is an effective mathematical programming technique that can handle optimization problems containing linear equations and inequalities, as well as second-order cone (i.e., quadratic inequalities) constraints. In the application of the present invention, it helps to solve specific parameters related to power quality management, such as photovoltaic machine cutting quantity, total network loss, etc., thereby achieving effective management of parallel power quality problems. In addition, the planning method proposed in the present invention also fully considers the actual situation of photovoltaic power generation and power grid operation. By introducing relevant parameters of photovoltaic power generation and online quantity, as well as information such as resistance and current of branches between nodes of the AC distribution network, the planning results are closer to the actual operating conditions, and the feasibility and practicality of the planning strategy are improved. In summary, the flexible interconnected distribution network planning method and system considering the management of parallel power quality problems proposed in the present invention not only have theoretical innovation and advancement, but also have broad prospects and important significance for practical application. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative labor. Among them:

[0041] Figure 1A method flow chart of a flexible interconnected distribution network planning method and system that considers and manages power quality issues provided by an embodiment of the present invention;

[0042] Figure 2 A schematic diagram of a flexible interconnection device including important load ports of a flexible interconnection distribution network planning method and system for considering and managing power quality issues provided by an embodiment of the present invention;

[0043] Figure 3 A schematic diagram of the basic principle of virtual synchronous machine control of a flexible interconnected distribution network planning method and system taking into account and managing power quality issues provided by an embodiment of the present invention;

[0044] Figure 4 A schematic diagram of a VSG control simulation example of a flexible interconnected distribution network planning method and system that takes into account and manages power quality issues provided by an embodiment of the present invention;

[0045] Figure 5 An internal structural diagram of a computer device of a flexible interconnected distribution network planning method and system that takes into account and manages power quality issues, provided in accordance with an embodiment of the present invention. DETAILED DESCRIPTION

[0046] In order to make the above-mentioned purposes, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the drawings of the specification. Obviously, the described embodiments are part of the embodiments of the present invention, but not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary persons in the art without creative work should fall within the scope of protection of the present invention.

[0047] Example 1

[0048] Reference Figure 1-Figure 3 , which is the first embodiment of the present invention, and provides a flexible interconnected distribution network planning method and system that considers and manages power quality issues, including:

[0049] In related technologies, power quality problems are complex and changeable, and often multiple problems coexist, posing a threat to the stability and security of the distribution network. Traditional distribution network planning methods often only focus on the management of a single power quality problem, and are unable to cope with the challenges of concurrent power quality problems.

[0050] This application provides a method that can effectively solve the above-mentioned problems. Next, we will combine multiple embodiments to explain in detail how to implement the flexible interconnected distribution network planning method that takes into account and manages power quality issues;

[0051] Figure 1A method flow chart of a flexible interconnected distribution network planning method and system considering and managing power quality issues is shown, including:

[0052] S101, establishing power quality transfer constraints for a target distribution network area including a flexible interconnection device according to a target distribution network area topology structure;

[0053] It should be noted that, in order to further improve the power quality of important loads, load ports can be added to the interconnection devices on both sides to address the problems existing in the current application of two-port flexible interconnection devices, such as Figure 2 As shown. It shows two circuit blocks with AC power input and DC output connected by a connecting line. Each circuit block contains a diode (indicated by a slash), which represents a rectifier or directional component used to process the AC signal and produce a DC output. In the circuit block on the left, the AC power supply (AC) is connected to the input of the diode, and the output of the diode is connected to the DC power supply (DC). The same structure also appears in the circuit block on the right. The two blocks are connected to each other by a horizontal connecting line, which may be used to transmit information or control signals.

[0054] Important loads with high power quality requirements are connected to the load port, and the port is used as the balancing node of the branch below, and mesh control is adopted. The advantage of this control method is that it can provide inertia support for the distribution line to which it belongs, and it is more sensitive to voltage changes and can make adjustments quickly. Since low-voltage substations are often flexibly interconnected in a back-to-back manner, the loss mainly comes from the inside of the equipment, which is generally about 2% of the power passing through the equipment. Therefore, it can be ignored during planning. In summary, at the steady-state level, for the flexible interconnected equipment at time t Phase, each port satisfies the following power quality transfer constraints:

[0055]

[0056] It should be noted that the first equation represents the Phase, active power from the grid and the active power from the load The sum is equal to the negative active power from the grid and the active power from the load This means that during this period, the net active power of the entire system is zero. The second equation shows that at time t, Phase, reactive power from the grid and reactive power from the load The sum is also equal to the negative reactive power from the grid and reactive power from the load Similarly, this also means that during this time period, the net reactive power of the entire system is also zero. The third inequality is a constraint condition, indicating that at time t, Phase, active power from the grid and reactive power The sum of the squares must be less than or equal to a maximum value Where S VSC is the rated capacity of the voltage source converter (VSC). This constraint ensures that the system does not exceed its design capacity.

[0057] In particular, for important load ports, due to the use of grid-type control, the voltage and frequency at the head end can be stabilized at the set value. In this model, since the subsequent Distflow form of the power flow model is used, the phase angle change is ignored, and the port constraints only consider the voltage:

[0058] V load1 =V load2 =V ref

[0059] Among them, V load1 Represents the voltage at load port 1, V load2 Represents the voltage at load port 2, V ref Represents the reference voltage. From the above description, it can be seen that flexible interconnection equipment can realize power transfer between multiple ports within the substation and power transfer between substations. However, in order to ensure the power quality of the downstream loads, important load ports are not suitable for connecting too many loads. If there are many important loads in the substation, the joint planning of flexible equipment and energy storage should be considered.

[0060] S102: Based on the power quality transfer constraints of the target distribution network area, a flexible interconnected distribution network planning model is established that takes into account the power quality problem governance;

[0061] In the embodiment of the present application, the flexible interconnected distribution network planning model considering the concurrent power quality problem management is a two-layer planning model, including an upper model and a lower model;

[0062] In an optional embodiment, the upper model includes: a first objective function and a first constraint condition;

[0063] The first objective function includes construction cost and operation cost;

[0064] The first constraint involves setting an upper limit on the cost.

[0065] In an optional embodiment, the lower model includes: a second objective function and a second constraint condition;

[0066] The second objective function is to minimize the sum of the total amount of photovoltaic daily cutting and the total daily network loss in the low-voltage AC / DC hybrid distribution network;

[0067] The second constraint conditions include power flow constraint, node voltage constraint, three-phase unbalance constraint, transformer heavy overload constraint and flexible interconnection device related operation constraints.

[0068] In an optional embodiment, the first objective function is expressed as:

[0069]

[0070] Among them, C build is the construction cost, including the civil engineering cost of equipment C basic , the cost brought by equipment capacity, that is, the unit capacity cost C power With capacity S VSC The product of the cost of the new line at the important load port, that is, the cost per unit length of the line C line and the total line length ∑d line The product of operation is the operating cost, which is fed back by the lower model.

[0071] The constraints of the upper model are relatively simple, mainly considering that the cost does not exceed the predetermined upper limit, that is, the first constraint is expressed as:

[0072] C up ≤C MAX

[0073] Since the location and capacity of the equipment are non-continuous variables and the upper model involves nonlinear variables and constraints, the upper model is suitable for solving by an intelligent algorithm. The present invention adopts a genetic algorithm (NSGA-Ⅱ) with an elite retention strategy.

[0074] It should be noted that the use of a genetic algorithm with an elite retention strategy to solve the above upper model can effectively handle complex nonlinear problems and search for the optimal solution by simulating the natural evolution process. This algorithm can search extensively in the solution space while maintaining the diversity of the population, thereby avoiding falling into a local optimal solution. In addition, the elite retention strategy ensures that the excellent individuals in each generation can be directly passed to the next generation, thereby accelerating the convergence speed of the algorithm.

[0075] During the solution process, the algorithm first randomly generates a certain number of initial populations, each of which represents a possible device configuration solution. Then, the algorithm evaluates these individuals according to the objective function and constraints, and selects individuals with higher fitness for crossover and mutation operations based on the evaluation results to generate new populations. This process will be repeated until the termination condition is met (such as reaching a predetermined number of iterations or the quality of the solution is no longer significantly improved).

[0076] Through this method, a series of equipment configuration schemes can be obtained, and the optimal scheme can be selected according to actual needs. This optimal scheme not only takes into account the construction cost and operation cost, but also takes into account the operation constraints of the flexible interconnection device and the need to manage the power quality issues, thereby achieving a balance between the economy and reliability of distribution network planning.

[0077] The second objective function is expressed as:

[0078] minF=f1ΔP PV +f2P loss

[0079] Among them, ΔP PV Represents the amount of photovoltaic cutting machine; P loss Represents the total network loss; f1 and f2 are weights. When setting, please note that the sum of the weights is 1.

[0080] In an optional embodiment, the second objective function further includes:

[0081]

[0082] Among them, Φ represents the set of three phases; N ACPV represents the set of nodes in the low-voltage AC distribution network; v(i) represents the node directly connected to node i; represents the phase, i.e., phase A, phase B, or phase C; Tmax represents the time node number, i.e., 24 hours; and They represent the branch between node i and node j in the AC distribution network. The resistance and current of each phase at time t; and They represent the amount of photovoltaic power generation and the amount connected to the grid in the AC distribution network respectively.

[0083] In the embodiment of the present application, the second constraint condition includes power flow constraint, node voltage constraint, three-phase imbalance constraint, transformer heavy overload constraint and flexible interconnection device related operation constraint.

[0084] Among them, since the phase of the low-voltage distribution network does not change much from the beginning to the end of the line, and considering the phase angle will greatly increase the difficulty of model solution and affect the solution speed, the power flow model used in the present invention adopts the Distflow form. In the process of calculating the power flow, the phase angle of the voltage is ignored and only the amplitude of the voltage is considered, so as to simplify the calculation process and reduce the time required for solution. The power flow constraints are as follows:

[0085] For the node j and branch ij in the low voltage AC distribution network, at time t:

[0086]

[0087]

[0088] Wherein, the set u(j) represents the set of first nodes of the branch with node j as the end node in the network; the set v(j) represents the set of last nodes of the branch with node j as the first node in the network; and It represents the active and reactive power of branch ij without deducting the network loss; is the voltage amplitude of the three phases at node i; and represents the resistance and reactance of branch ij; and are the injected amounts of three-phase active and reactive power of node j respectively.

[0089] It should be noted that in order to ensure the power quality of the interconnected substations, the node voltage needs to be limited within the qualified range. For low-voltage substations, according to national standards, the node voltages in all substations need to be maintained at 90% to 107% of the nominal voltage, that is, the constraints in the node voltage constraint below need to be satisfied:

[0090]

[0091] Among them, V max and V min are the upper and lower limits of the node voltage amplitude respectively.

[0092] It should be noted that for each node in the low-voltage AC distribution network, the voltage three-phase imbalance cannot exceed the maximum value of the three-phase imbalance, that is, it must satisfy the constraints in the following three-phase imbalance constraint:

[0093]

[0094] in, represents the voltage imbalance at node i, It represents the maximum permissible value of the three-phase voltage imbalance of the distribution network, which is 4% in this application.

[0095] It should be noted that in order to solve a series of power quality problems caused by heavy overload, when photovoltaic power cannot be fully absorbed, it is necessary to ensure that the transformers of each interconnected area are not overloaded in both directions within a day. That is, for each area, the constraints in the following transformer heavy overload constraints must be met:

[0096]

[0097] Among them, S N is the transformer capacity.

[0098] It should be noted that in order to use flexible interconnected devices to achieve power mutual assistance between stations, it is necessary to model the dispatching capacity of flexible devices and establish relevant constraints. That is, the power quality transfer constraint needs to be considered in the optimization model. It should be noted that V load1 =V load2 =V ref The corresponding constraints only take effect on important load ports that need to be balancing nodes.

[0099] It should be noted that through the iterative solution process, various constraints can be fully considered to ensure that the planning scheme not only meets the economic requirements, but also effectively manages and solves the power quality problems. In addition, this method also improves the flexibility of the solution, allowing the weights and constraints of the objective function to be adjusted according to actual needs at different iteration stages to further optimize the planning scheme. In the end, the optimal solution obtained not only helps to improve the reliability and economy of the distribution network, but also provides a strong reference and reference for future distribution network planning.

[0100] S103, combining the genetic algorithm with the elite retention strategy and the second-order cone to solve the flexible interconnected distribution network planning model considering the management of parallel power quality problems, obtain the flexible interconnected distribution network planning strategy considering the management of parallel power quality problems, and establish a simulation model to verify the regulatory effect of the solved flexible interconnected distribution network planning strategy considering the management of parallel power quality problems.

[0101] In the embodiment of the present application, the flexible interconnected distribution network planning model considering the management of power quality issues is solved by combining a genetic algorithm with an elite retention strategy and a second-order cone, including:

[0102] The upper model of the flexible interconnected distribution network planning model considering power quality issues is solved by combining a genetic algorithm with an elite retention strategy.

[0103] The lower model in the flexible interconnected distribution network planning model that takes into account the management of power quality issues is solved by combining the second-order cone.

[0104] In the embodiment of the present application, the lower model is converted into a second-order cone solution. The lower model is a typical mixed integer nonlinear nonconvex programming problem, which belongs to a non-deterministic polynomial problem. The power flow constraints and node voltage constraints are nonlinear or non-convex equations, which cannot be directly solved using commercial solvers. Therefore, these equations are converted into second-order cones. The transformed form is as follows:

[0105]

[0106] in, These are the phases of the AC network from node i to node j. Active and reactive power flows at time t. Represents the phase from node to node j The value of the current at time after second-order cone transformation. are the resistance component and reactance component of the line impedance, corresponding to the phase from node i to node j. The situation at time t. Indicates that after the transformation, node i is in phase The voltage amplitude at time t. The set u(j) contains all upstream nodes connected to node j, while the set v(j) contains all downstream nodes. k∈v(j) refers to any element K in the set v(j), that is, a downstream neighbor node of node j. ∥·∥2 represents the Euclidean norm, that is, the L2 norm of the vector. ∑ represents the summation operation of the items in the specified range.

[0107] Since the node voltage constraints and are themselves in the form of cones, they can be directly retained in the second-order cone programming model. At this point, the model convexification is completed, and the final structure of the optimization model proposed in this application can be solved using commercial solvers such as CPLEX.

[0108] In the embodiment of the present application, in order to solve the power quality problem of voltage sag on a smaller time scale, it is necessary to stabilize the voltage of important load ports by control on the basis of scheduling. Therefore, the present invention adopts meshed control to achieve this goal. The meshed control block diagram based on the virtual synchronous machine is as follows: Figure 3 Shown: ω ref is the reference speed, which is generated by an external controller or a predetermined strategy. k0 is the proportional constant; ω n is the natural oscillation frequency of the system; the function of this link is to adjust the speed deviation to keep the system frequency constant. D represents the differential term, which is used to eliminate the error; this link is used to calculate the required active power P and reactive power Q. U ref is the reference voltage, which is generated by an external controller or a predetermined strategy; E0 is the electromotive force of the generator. m and θ e are the mechanical angle and electromagnetic angle of the motor respectively; ω m is the actual speed of the motor; L and R are the inductance and resistance of the motor respectively; i abc is the three-phase current; i set is the set current value; PR and SVPWM refer to sinusoidal wave modulation (PR) and space vector pulse width modulation (SVPWM) in pulse width modulation (PWM) technology. abc is the three-phase voltage; U is the total voltage; I is the total current; this link is responsible for decomposing the total voltage and current into the voltage and current of each phase for independent control. There are multiple feedback loops in the system, such as the actual speed of the motor ωm to the frequency controller, and from the actual current i abc to virtual synchronous motor models, etc. These feedback loops help optimize system stability and dynamic performance. This system achieves real-time compensation for grid voltage fluctuations by simulating the behavior of synchronous generators, thereby ensuring voltage stability at important load ports. Through reasonable parameter settings and control strategies, voltage sags can be effectively addressed and power quality can be improved.

[0109] In order to verify the effect of this control method, a typical virtual synchronous machine control model was built in Simulink. Figure 4 As shown in the figure, the effect of the proposed method is verified.

[0110] It should be noted that the present invention analyzes the power dispatching capability of the flexible interconnection device containing important load ports in the distribution network topology of large-scale photovoltaic access; based on the capacity constraints of the flexible equipment, a two-layer planning model considering the management of parallel power quality issues is established to solve the voltage over-limit, three-phase voltage imbalance, and heavy overload problems at the steady-state level; for short-term voltage sag problems, a grid-type inverter simulation model for voltage sag is built to stabilize the voltage of the port. In summary, the present invention can consider the management of parallel power quality issues, give full play to the capabilities of flexible interconnection equipment in power dispatching, voltage support, etc., and ensure the power quality of the substation.

[0111] This embodiment also provides a flexible interconnected distribution network planning system that takes into account and manages power quality issues, including:

[0112] A structural analysis module is used to establish power quality transfer constraints of the target distribution network area including flexible interconnection devices according to the topological structure of the target distribution network area;

[0113] A model building module is used to establish a flexible interconnected distribution network planning model that takes into account power quality issues and manages them based on the power quality transfer constraints of the target distribution network area;

[0114] The flexible interconnected distribution network planning model that considers power quality problem management is a two-layer planning model, including an upper model and a lower model.

[0115] The model solving module is used to solve the flexible interconnected distribution network planning model considering the management of parallel power quality problems by combining the genetic algorithm with the elite retention strategy and the second-order cone, obtain the flexible interconnected distribution network planning strategy considering the management of parallel power quality problems, and establish a simulation model to verify the regulatory effect of the solved flexible interconnected distribution network planning strategy considering the management of parallel power quality problems.

[0116] The above-mentioned unit modules may be embedded in or independent of the processor in the computer device in the form of hardware, or may be stored in the memory in the computer device in the form of software, so that the processor can call and execute the operations corresponding to the above-mentioned modules.

[0117] This embodiment also provides a computer device, which may be a terminal, and its internal structure diagram may be as shown in FIG. Figure 5 As shown. The computer device includes a processor, a memory, a communication interface, a display screen and an input device connected through a system bus. Among them, the processor of the computer device is used to provide computing and control capabilities. The memory of the computer device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system and a computer program. The internal memory provides an environment for the operation of the operating system and the computer program in the non-volatile storage medium. The communication interface of the computer device is used to communicate with an external terminal in a wired or wireless manner, and the wireless manner can be achieved through WIFI, an operator network, NFC (near field communication) or other technologies. When the computer program is executed by the processor, a flexible interconnected distribution network planning method that considers and manages power quality issues is implemented. The display screen of the computer device can be a liquid crystal display screen or an electronic ink display screen, and the input device of the computer device can be a touch layer covered on the display screen, or a button, trackball or touchpad set on the computer device housing, or an external keyboard, touchpad or mouse.

[0118] This embodiment further provides a computer-readable storage medium, on which a computer program is stored. When the computer program is executed by a processor, the following steps are implemented:

[0119] According to the topological structure of the target distribution network area, the power quality transfer constraints of the target distribution network area with flexible interconnection devices are established;

[0120] Based on the power quality transfer constraints of the target distribution network area, a flexible interconnected distribution network planning model is established that takes into account the power quality problem governance.

[0121] The flexible interconnected distribution network planning model that considers power quality problem management is a two-layer planning model, including an upper model and a lower model.

[0122] The genetic algorithm with elite retention strategy and the second-order cone are used to solve the flexible interconnected distribution network planning model considering the management of parallel power quality problems, and the flexible interconnected distribution network planning strategy considering the management of parallel power quality problems is obtained. A simulation model is established to verify the regulatory effect of the solved flexible interconnected distribution network planning strategy considering the management of parallel power quality problems.

[0123] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

[0124] Those skilled in the art will appreciate that the embodiments of the present application can be provided as methods, systems, or computer program products. Therefore, the present application can adopt the form of complete hardware embodiments, complete software embodiments, or embodiments in combination with software and hardware. Moreover, the present application can adopt the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) that contain computer-usable program code. The scheme in the embodiments of the present application can be implemented in various computer languages, for example, object-oriented programming language Java and literal scripting language JavaScript, etc.

[0125] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0126] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture including an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0127] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1The steps for the functions specified in one or more boxes.

[0128] Although the preferred embodiments of the present application have been described, those skilled in the art may make other changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications falling within the scope of the present application.

[0129] Obviously, those skilled in the art can make various changes and modifications to the present application without departing from the spirit and scope of the present application. Thus, if these modifications and variations of the present application fall within the scope of the claims of the present application and their equivalents, the present application is also intended to include these modifications and variations.

Claims

1. A flexible interconnected distribution network planning method considering and managing power quality issues, characterized in that: include: According to the topological structure of the target distribution network area, the power quality transfer constraints of the target distribution network area with flexible interconnection devices are established; Based on the power quality transfer constraints of the target distribution network area, a flexible interconnected distribution network planning model that takes into account power quality problem management is established; The flexible interconnected distribution network planning model that takes into account and manages power quality issues is a two-layer planning model, including an upper model and a lower model; The flexible interconnected distribution network planning model considering the management of parallel power quality issues is solved by combining a genetic algorithm with an elite retention strategy and a second-order cone, and a flexible interconnected distribution network planning strategy considering the management of parallel power quality issues is obtained. A simulation model is established to verify the regulatory effect of the solved flexible interconnected distribution network planning strategy considering the management of parallel power quality issues.

2. The flexible interconnected distribution network planning method considering and managing power quality issues as claimed in claim 1 is characterized in that: The upper model includes: a first objective function and a first constraint condition; The first objective function includes construction cost and operation cost; The first constraint includes setting a cost cap.

3. The flexible interconnected distribution network planning method considering and managing power quality issues as claimed in claim 2 is characterized in that: The lower model includes: a second objective function and a second constraint condition; The second objective function is to minimize the sum of the total amount of photovoltaic daily cutting and the total daily network loss in the low-voltage AC / DC hybrid distribution network; The second constraint conditions include power flow constraint, node voltage constraint, three-phase imbalance constraint, transformer heavy overload constraint and flexible interconnection device related operation constraints.

4. The flexible interconnected distribution network planning method considering and managing power quality issues as claimed in claim 3 is characterized in that: The solution of the flexible interconnected distribution network planning model considering and managing power quality issues by combining the genetic algorithm with the elite retention strategy and the second-order cone includes: The upper model in the flexible interconnected distribution network planning model that takes into account and manages power quality issues is solved by combining a genetic algorithm with an elite retention strategy; The lower model in the flexible interconnected distribution network planning model that takes into account and manages power quality issues is solved by combining the second-order cone.

5. The flexible interconnected distribution network planning method considering and managing power quality issues as claimed in claim 4 is characterized in that: The first objective function is expressed as: Among them, C build is the construction cost, including the civil engineering cost of equipment C basic , the cost brought by equipment capacity, that is, the unit capacity cost C power With capacity S VSC The product of the cost of the new line at the important load port, that is, the cost per unit length of the line C line and the total line length ∑d line The product of operation is the operating cost, which is fed back by the lower model.

6. The flexible interconnected distribution network planning method considering and managing power quality issues as claimed in claim 5 is characterized in that: The second objective function is expressed as: minF=f1ΔP PV +f2P loss Among them, ΔP PV Represents the amount of photovoltaic cutting machine; P loss Represents the total network loss; f1 and f2 are weights. When setting, please note that the sum of the weights is 1.

7. The flexible interconnected distribution network planning method considering and managing power quality issues as claimed in claim 6, characterized in that: The second objective function also includes: Among them, Φ represents the set of three phases; N ACPV represents the set of nodes in the low-voltage AC distribution network; v(i) represents the node directly connected to node i; Represents phase, i.e. phase A, phase B or phase C; T max Represents the number of time nodes, i.e. 24 hours; and They represent the branch between node i and node j in the AC distribution network. The resistance and current of each phase at time t; and They represent the amount of photovoltaic power generation and the amount connected to the grid in the AC distribution network respectively.

8. A flexible interconnected distribution network planning system that considers and manages power quality issues, characterized in that: include: A structural analysis module is used to establish power quality transfer constraints of the target distribution network area including flexible interconnection devices according to the topological structure of the target distribution network area; A model building module, used to establish a flexible interconnected distribution network planning model that takes into account power quality problem management based on the power quality transfer constraints of the target distribution network area; The flexible interconnected distribution network planning model that takes into account and manages power quality issues is a two-layer planning model, including an upper model and a lower model; The model solving module is used to solve the flexible interconnected distribution network planning model considering the management of parallel power quality problems by combining a genetic algorithm with an elite retention strategy and a second-order cone, obtain a flexible interconnected distribution network planning strategy considering the management of parallel power quality problems, and establish a simulation model to verify the regulatory effect of the solved flexible interconnected distribution network planning strategy considering the management of parallel power quality problems.

9. A computer device comprising a memory and a processor, wherein the memory stores a computer program, wherein: When the processor executes the computer program, the steps of the method according to any one of claims 1 to 7 are implemented.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the method according to any one of claims 1 to 7 are implemented.

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