Method and system for optimizing capacity coordination of reactive power compensation device and hvdc station

Abstract

This invention belongs to the field of power system planning and operation, and particularly relates to a method and system for optimizing the coordinated capacity configuration of flexible DC converter stations and reactive power compensation devices. It includes constructing a flexible DC interconnection model and establishing a flexible DC converter station... P - Q The coupling characteristic curve is calculated. Based on the real-time reactive power demand of the system and the dynamic response weight of the flexible DC-DC converter station, the equivalent substitution coefficient of the flexible DC-DC interconnection for the traditional reactive power compensation device is calculated. Using the marginal cost analysis method, the marginal impact index of active and reactive power regulation demand on the overall net benefit of the system is calculated, and it is determined whether the flexible DC-DC interconnection device alone can meet the system's reactive power demand. If not, the reactive power gap is calculated and the traditional reactive power compensation device is configured. If it meets the demand, the optimal capacity configuration result of the flexible DC-DC converter station and the reactive power compensation device is obtained by maximizing the overall net benefit function of the system. This invention significantly improves the utilization rate of power electronic assets and the economy of power grid construction while ensuring the transient security support of the power grid.

Description

Technical Field

[0001] This invention belongs to the field of power system planning and operation technology, and particularly relates to a method and system for optimizing the capacity coordinated configuration of flexible DC converter stations and reactive power compensation devices. Background Technology

[0002] With the construction of new power systems, AC / DC hybrid distribution networks have become an important trend in distribution network development. Voltage Source Converters (VSCs), as core equipment connecting AC and DC power grids, not only have the ability to control active power flow but also possess four-quadrant operation characteristics, enabling them to independently regulate reactive power, thereby providing voltage support for the AC system.

[0003] From the perspective of steady-state operation of new power distribution systems, existing converter capacity configurations often suffer from functional fragmentation and resource idleness. Traditional power grid planning typically anchors the capacity configuration of voltage source converters primarily to the expected DC load level or the maximum external transmission demand of distributed energy, focusing mainly on their active power transmission channel function. However, for the reactive power required for steady-state system operation, planners tend to configure dedicated compensation equipment such as capacitor banks, static var compensators (SVCs), or static var generators according to traditional AC distribution network design specifications. This configuration model ignores the fact that voltage source converters often do not reach full load under most steady-state operating conditions, resulting in the ineffective utilization of the converter's remaining apparent power capacity for reactive power regulation, leading to a hidden waste of power electronic assets and redundancy in power grid construction investment.

[0004] In the transient operation of new power distribution systems, with the increasing level of power electronics, the requirements for dynamic voltage support capabilities are becoming increasingly stringent. Although traditional reactive power compensation devices can maintain voltage stability to some extent, mechanically switched devices have slow response speeds and are unable to cope with rapid voltage drops; even static var generators with faster response speeds have relatively high configuration costs. Voltage source converters, with their fully controlled device characteristics, possess extremely fast dynamic response speeds and can theoretically replace traditional devices in emergency transient voltage support. However, during transient impacts such as short-circuit faults, the system often requires huge reactive current support. If the capacity of the voltage source converter is designed only based on steady-state active power demand, its current limiting circuit is easily triggered during transient processes, resulting in limited reactive power output and inability to meet the requirements for low-voltage ride-through or transient recovery.

[0005] Therefore, how to quantitatively analyze the substitution efficiency of voltage source converters for traditional reactive power compensation devices from the perspective of the economics of functional substitution, while ensuring the steady-state operation and transient safety support of the distribution network, and how to calculate the marginal balance point between the expansion cost of converters and the cost savings of traditional equipment based on the equivalent substitution coefficient, has become a key technical problem that urgently needs to be solved in the planning of AC / DC hybrid distribution networks. Summary of the Invention

[0006] To overcome the shortcomings of the prior art, this invention provides a method and system for optimizing the capacity coordination of flexible DC converter stations and reactive power compensation devices. By establishing a PQ coupled operation model of flexible DC interconnection, the equivalent substitution relationship of flexible DC interconnection for traditional reactive power compensation devices is derived. Marginal effect analysis is introduced to construct a comprehensive model that includes equipment investment costs and substitution benefits, thereby determining the optimal economic ratio between VSC capacity and traditional reactive power compensation capacity.

[0007] To achieve the above objectives, one or more embodiments of the present invention provide the following technical solutions: The first aspect of this invention provides a method for optimizing the capacity coordination of flexible DC converter stations and reactive power compensation devices.

[0008] The method for optimizing the capacity coordination of flexible DC converter stations and reactive power compensation devices includes the following steps: Obtain the distribution network topology and operating parameters, and construct a flexible DC interconnection model; Building a flexible DC converter station P - Q The coupling characteristic curves are used to determine the apparent power capacity constraints, power flow constraints, and physical constraints of the power equipment at the flexible DC converter station. Based on the real-time reactive power demand of the system and the dynamic response weight of the flexible DC converter station, the equivalent substitution coefficient of the flexible DC interconnection for the traditional reactive power compensation device is calculated. Using marginal cost analysis, the marginal impact index of active and reactive power regulation demand on the overall net revenue of the system is calculated, and the marginal impact index is used to determine whether the reactive power demand of the system can be met by using the flexible DC interconnect device alone. If the conditions are not met, calculate the reactive power deficit and configure a traditional reactive power compensation device. If the conditions are met, there is no need to configure a traditional reactive power compensation device, and the optimal capacity configuration result of the flexible DC converter station and the reactive power compensation device can be obtained by maximizing the system's optimized net benefit function.

[0009] The second aspect of the present invention provides a system for the coordinated configuration optimization of the capacity of flexible DC converter stations and reactive power compensation devices.

[0010] The system for coordinated configuration optimization of flexible DC converter stations and reactive power compensation devices includes: The interconnection modeling module is configured to: acquire the distribution network topology and operating parameters, and construct a flexible DC interconnection model; The constraint establishment module is configured to: establish the constraints of the flexible DC converter station. P - Q The coupling characteristic curves are used to determine the apparent power capacity constraints, power flow constraints, and physical constraints of the power equipment at the flexible DC converter station. The equivalent substitution analysis module is configured to calculate the equivalent substitution coefficient of the flexible DC interconnect for the traditional reactive power compensation device based on the real-time reactive power demand of the system and the dynamic response weight of the flexible DC converter station. The marginal benefit assessment module is configured to: use the marginal cost analysis method to calculate the marginal impact index of active and reactive power regulation demand on the overall net revenue of the system, and determine whether the flexible DC interconnection device alone can meet the reactive power demand of the system based on the marginal impact index. The capacity collaborative optimization module is configured as follows: If the conditions are not met, calculate the reactive power deficit and configure a traditional reactive power compensation device. If the conditions are met, there is no need to configure a traditional reactive power compensation device, and the optimal capacity configuration result of the flexible DC converter station and the reactive power compensation device can be obtained by maximizing the system's optimized net benefit function.

[0011] The above one or more technical solutions have the following beneficial effects: This invention provides a method and system for optimizing the capacity coordination of flexible DC converter stations and reactive power compensation devices, by establishing a flexible DC interconnection. P - Q A coupled operation model was developed to accurately derive the dynamic equivalent substitution coefficient of flexible DC converter equipment for traditional reactive power compensation devices. By introducing marginal effect analysis from engineering economics, a comprehensive net benefit model was constructed, incorporating equipment lifecycle costs, land shadow price costs, and reliability benefits. Furthermore, the marginal impact index of active and reactive power regulation demand on investment returns was quantified. This invention can effectively identify the reactive power regulation potential of flexible DC converter stations under non-full-load conditions, determine the optimal capacity ratio between the converter station and traditional reactive power equipment based on the marginal cost equilibrium point, and effectively solve the problems of resource idleness and redundant investment caused by functional fragmentation in AC / DC distribution networks. While ensuring the transient security support of the power grid, it significantly improves the utilization rate of power electronic assets and the economic efficiency of power grid construction.

[0012] Advantages of additional aspects of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0013] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0014] Figure 1 This is a flowchart illustrating the method steps of Example 1.

[0015] Figure 2 This is a flowchart of the method in Example 1.

[0016] Figure 3 This is the physical topology circuit diagram of VSC interconnection in Example 1.

[0017] Figure 4 Example 1 Figure 3 The equivalent circuit diagram.

[0018] The attached diagram lists the components represented by each number as follows: 1. DC interconnection line; 2. First AC side; 3. First circuit breaker; 4. First transformer; 5. First disconnect switch; 6. First synchronous compensator; 7. First DC side VSC; 8. Second AC side; 9. Second circuit breaker; 10. Second transformer; 11. Second disconnect switch; 12. Second synchronous compensator; 13. Second DC side VSC; 14. First terminal equivalent AC signal source; 15. First terminal AC equivalent impedance; 16. First AC side common coupling point PCC equivalent voltage source; 17. First DC side VSC output equivalent voltage source; 18. Second terminal equivalent AC signal source; 19. Second terminal AC equivalent impedance; 20. Second AC side common coupling point PCC equivalent voltage source; 21. Second DC side VSC output equivalent voltage source. Detailed Implementation

[0019] It should be noted that the following detailed descriptions are exemplary and intended to provide further illustration of the invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0020] It should be noted that the terminology used herein is for the purpose of describing particular implementations only and is not intended to limit the exemplary implementations of the present invention.

[0021] Where there is no conflict, the embodiments and features in the embodiments of the present invention can be combined with each other.

[0022] Example 1 This embodiment discloses an optimization method for the coordinated capacity configuration of flexible DC converter stations and reactive power compensation devices, considering the functional substitution effect. This method establishes a flexible DC interconnection... P - QA coupled operation model was developed to accurately derive the dynamic equivalent substitution coefficient of flexible DC converter equipment for traditional reactive power compensation devices. By introducing marginal effect analysis from engineering economics, a comprehensive net benefit model was constructed, incorporating equipment lifecycle costs, land shadow price costs, and reliability benefits. Furthermore, the marginal impact index of active and reactive power regulation demand on investment returns was quantified. This invention can effectively identify the reactive power regulation potential of flexible DC converter stations under non-full-load conditions, determine the optimal capacity ratio between the converter station and traditional reactive power equipment based on the marginal cost equilibrium point, and effectively solve the problems of resource idleness and redundant investment caused by functional fragmentation in AC / DC distribution networks. While ensuring the transient security support of the power grid, it significantly improves the utilization rate of power electronic assets and the economic efficiency of power grid construction.

[0023] like Figure 1 As shown, the method for optimizing the capacity coordination of flexible DC converter stations and reactive power compensation devices includes the following steps: Obtain the distribution network topology and operating parameters, and construct a flexible DC interconnection model; Building a flexible DC converter station P - Q The coupling characteristic curves are used to determine the apparent power capacity constraints, power flow constraints, and physical constraints of the power equipment at the flexible DC converter station. Based on the real-time reactive power demand of the system and the dynamic response weight of the flexible DC converter station, the equivalent substitution coefficient of the flexible DC interconnection for the traditional reactive power compensation device is calculated. Using marginal cost analysis, the marginal impact index of active and reactive power regulation demand on the overall net revenue of the system is calculated, and the marginal impact index is used to determine whether the reactive power demand of the system can be met by using the flexible DC interconnect device alone. If the conditions are not met, calculate the reactive power deficit and configure a traditional reactive power compensation device. If the conditions are met, there is no need to configure a traditional reactive power compensation device, and the optimal capacity configuration result of the flexible DC converter station and the reactive power compensation device can be obtained by maximizing the system's optimized net benefit function.

[0024] The apparent power capacity constraints mentioned above correspond to the active-reactive power circle constraints described by the PQ coupling characteristic curve, as well as the reactive power limit, etc. Power flow constraints correspond to the AC-side power balance equations; Physical constraints on power equipment include VSC current limits, voltage operating range, and switching frequency limits.

[0025] Overall, this embodiment establishes a PQ-coupled operation model for flexible DC-DC interconnection to derive the equivalent substitution relationship between flexible DC-DC interconnection and traditional reactive power compensation devices. It introduces marginal effect analysis to construct a comprehensive model that includes equipment investment costs and substitution benefits, thereby determining the optimal economic ratio between VSC capacity and traditional reactive power compensation capacity. The technical solution of this embodiment will be further explained in detail below with reference to the accompanying drawings.

[0026] For medium-voltage distribution networks, a flexible interconnection topology model based on chain-type reactive power compensation is first established. Figure 3 This is the single-phase equivalent circuit diagram of the VSC interconnect proposed in this embodiment. (See diagram below.) Figure 3 As shown, the topology consists of two sets of chained static synchronous compensators connected to two feeders respectively, and a small-capacity back-to-back voltage source converter connected between the neutral points of the two sets of chained static synchronous compensators.

[0027] In this topology, the H-bridge modules of each phase of the chain-type static synchronous compensator serve as the main withstand voltage and current-carrying components, while also handling the reactive power regulation current within the feeder and the active power transmission current between feeders; the flexible DC interconnect is mainly used to maintain the neutral point potential and control the direction of active power flow.

[0028] For ease of description, one side of DC interconnection line 1 will be referred to as the first terminal, and the other side of DC interconnection line 1 will be referred to as the second terminal. Specifically, Figure 3 The left side of DC interconnection line 1 is called the first terminal, and the right side of DC interconnection line 1 is called the second terminal. Wherein: The first end, along the direction gradually approaching the DC interconnection line 1, includes the first AC side 2, the first circuit breaker 3, the first transformer 4, the first disconnect switch 5, the first synchronous compensator 6, and the first DC side VSC7 in sequence; The second end of the DC interconnection line 1 has the same structure, and in sequence along the direction gradually approaching the DC interconnection line 1, it includes a second AC side 8, a second circuit breaker 9, a second transformer 10, a second disconnect switch 11, a second synchronous compensator 12, and a second DC side VSC 13.

[0029] Figure 4 for Figure 3 Equivalent model diagram of the topology component. Figure 4 In the middle, Figure 3 The equivalent model of the first end of the DC interconnection line 1 is called feeder 1. Figure 3 The equivalent model of the second end of the DC interconnection line 1 is called feeder 2. Wherein: The feeder includes a first-end equivalent AC signal source 14, a first-end equivalent AC impedance 15, an equivalent voltage source 16 of the first AC side common connection point PCC, and an equivalent voltage source 17 of the first DC side VSC output. Feeder 2 includes a second-terminal equivalent AC signal source 18, a second-terminal equivalent AC impedance 19, a second-terminal equivalent voltage source 20 of the second AC side common connection point PCC, and a second-terminal equivalent voltage source 21 of the second DC side VSC output.

[0030] Furthermore, Figure 4 middle: and These are the voltage phasors on both sides of the interconnection AC circuit. This represents the equivalent AC voltage phasor of the feeder. This represents the equivalent voltage amplitude of the feeder. This indicates the phase angle of the equivalent voltage of the feeder. Indicates the angle symbol; This represents the equivalent AC voltage phasor of the feeder. This indicates the equivalent voltage amplitude of the feeder. This indicates the phase angle of the second equivalent voltage of the feeder; X 1 and X 2 represents the equivalent impedance of feeder one and feeder two, respectively; , This represents the equivalent voltage phasor at the PCC point on the AC side of the feeder. This indicates the voltage amplitude at point PCC on the feeder. This indicates the voltage phase angle at point PCC on the feeder. , This represents the equivalent voltage phasor at the PCC point on the AC side of feeder two. This indicates the voltage amplitude at point PCC of feeder two. This indicates the voltage phase angle at point PCC of the feeder. and This represents the fundamental voltage vector referred from the AC side to the primary side output, where n represents the transformer turns ratio. This represents the fundamental voltage phasor of the first DC-side VSC. This indicates the output voltage amplitude of the first DC side VSC. This indicates the output voltage phase angle of the first DC side VSC; This represents the fundamental voltage phasor of the second DC-side VSC. This indicates the output voltage amplitude of the second DC side VSC. This indicates the phase angle of the output voltage of the second DC side VSC; This represents the alternating current on one side of the feeder, where, This indicates the magnitude of the alternating current on one side of the feeder. The current phase angle represents the alternating current on one side of the feeder. This represents the alternating current on both sides of the feeder, where, This indicates the current amplitude of the alternating current on both sides of the feeder. This represents the phase angle of the alternating current on both sides of the feeder.

[0031] The power on one side of the feeder can be calculated using formula (1): (1) In formula (1): P 1. Q 1 represents the active and reactive power of feeder 1, respectively; j is the imaginary unit; "*" indicates conjugate; It represents the conjugate phasor of the alternating current on one side of the feeder.

[0032] As can be seen from formula (1), the active power on one side of the feeder can be adjusted through flexible DC interconnection. P C1 With reactive power Q C1 Expressed by the following formula (2): (2) Formula (2) shows that by controlling the output of the VSC flexible DC interconnect on one side of the feeder, the amplitude of the fundamental voltage can be increased. U C1 and phase α 1. This allows for the decoupling and continuous adjustment of the active and reactive power absorbed (generated) by the flexible DC interconnect on one side of the feeder. Specifically, when... α 1 and θ 1. In-phase or out-of-phase, flexible DC interconnection outputs maximum reactive power, while active power... P ref Under confirmed conditions, the theoretical limit of reactive power compensation is expressed by formula (3): (3) In formula (3), This represents the theoretical limit capacity of the converter's reactive power compensation. This indicates the maximum allowable output current on the AC side of the converter. P ref This indicates the active power reference command value for the flexible DC converter station.

[0033] The active power regulated by the STATCOM on the same side P p1 reactive power Q p1 Expressed by formula (4): (4) In formula (4), P p1 This indicates the active power regulated by the first-end synchronous compensator.Q p1 This indicates the reactive power regulated by the first-end synchronous compensator.

[0034] The actual total voltage vector applied to the system is To maximize reactive power, adjustments are needed. phase , so that the current vector generated by it With system voltage They form a 90-degree angle.

[0035] This invention introduces engineering economics and resource constraint theory to construct a comprehensive benefit evaluation model, namely a comprehensive net benefit function. NBS (NetBenefitSurplus, NBS). Overall Net Income Function NBS It integrates the lifecycle value difference of flexible DC-DC interconnection facilities, the land resource constraint costs based on land shadow prices, and the reliability improvement benefits, specifically: The difference in the total lifecycle value of flexible direct current interconnection facilities Δ LCC : Calculate the cost difference between the flexible DC solution and the equivalent traditional solution in terms of initial investment, operation and maintenance, and time value of money.

[0036] Land resource constraint cost Δ based on land shadow price C Land To address the scarcity of land resources in urban load centers, this paper introduces the theory of land opportunity cost and constructs a system based on land shadow prices. λ shadow The nonlinear penalty model quantifies the cost triggered by the expansion scheme of auxiliary adjustment equipment due to excessive land occupation, as shown in formula (5): (5) In formula (5), This represents the function that takes the maximum value. β It is the equivalent floor space factor per unit capacity, used to characterize the average floor space intensity of different types of traditional regulating equipment; This indicates the configuration capacity of the equivalent replacement traditional reactive power compensation equipment. A avail This represents the available area at the existing site.

[0037] The capacity coordination optimization process introduces a nonlinear penalty model for the scarcity of land in urban load centers, and incorporates the equipment footprint intensity into the spatial cost as an optimization objective.

[0038] Furthermore, the NetBenefitSurplus (NBS) function integrates the value of equipment, the value of space, and the benefits of improved reliability. B Rel It can be expressed by formula (6): (6) In formula (6), each Δ is defined as "traditional solution cost - flexible DC solution cost". If NBS A value >0 indicates that the flexible straight-line solution is economically viable as an alternative.

[0039] To avoid blind expansion, sensitivity analysis is used to analyze the coupling relationship between safety requirements and investment costs. The required capacity of a single converter station is defined. S req Let be the envelope value of the steady-state operating requirements and the transient limit requirements. Based on Lagrange duality analysis in optimization theory, solve for the Lagrange multipliers corresponding to the transient frequency / voltage safety constraints of the system. λ * P and λ * Q A quantitative index of the marginal impact of active / reactive power adjustment demand on overall net income. MII P and MII Q As shown in formula (7): (7) In formula (7), This represents the optimal overall net profit value of the system; This represents the required active power regulation capacity under system transient frequency security constraints. This indicates the required reactive power regulation capacity under system voltage safety constraints. λ * P This indicates the Lagrange multiplier corresponding to the system's transient frequency; λ * Q This indicates the Lagrange multiplier corresponding to the voltage safety constraint; MII P This index represents the marginal impact of active power regulation demand on overall net income. MII Q This index represents the marginal impact of reactive power regulation demand on overall net income.

[0040] In this embodiment, the active power adjustment marginal impact index is obtained by solving the Lagrange multipliers corresponding to the system security constraints. MII P and reactive power adjustment marginal impact index MII Q Quantify the marginal contribution of various adjustment demands to investment returns.

[0041] Based on the above analysis, a multi-dimensional collaborative model that balances economy and security is constructed: To optimize the net return functionF With the goal of maximizing the system's safety and stability margin, a preliminary rated capacity is established. S nom Nonlinear programming model As shown in formula (8): (8) In formula (8), Indicates initial rated capacity S nom Let be the objective function for maximizing the decision variables; This represents a nonlinear constraint penalty term that includes the marginal impact index.

[0042] The optimal solution when the model converges S * nom This represents the preliminary result of the converter station capacity configuration.

[0043] Based on the preliminary results of the flexible DC converter station capacity configuration, determine whether using the flexible DC interconnect device alone can meet the system's reactive power requirements, specifically including: Based on a single converter station i The initial capacity configuration is as follows S nom,i The proposed solution is to optimize capacity to determine the optimal interconnection capability for a given network. P ij In this case, a single-site VSC for flexible direct connection i Optimal capacity S i It can be expressed by formula (9): (9) in, S nom,i Indicates a single converter station i The initial rated capacity; P ij Converter station i and j Available power capacity for interconnection between them j Indicates the converter station i The node index number of the connected peer converter station, where n represents the total number of converter stations participating in the interconnection in the system. γ ij ∈[0,1] represents the effective coefficients of interconnect power available in extreme scenarios.

[0044] It can be understood that DC interconnection has VSCs on both sides (i.e. Figure 3 The first DC-side VSC and the second DC-side VSC are mentioned. Here, formula (9) calculates the optimal capacity of a single-side VSC. i Indicates the first DC-side VSC or the second DC-side VSC.i The value can be 1 or 2.

[0045] To conduct an economic comparison, it is necessary to define the equivalent substitution coefficient η for traditional reactive power equipment using flexible DC-DC interconnection. sub The calculation incorporates the system's reactive power demand curve. Q demand ( t ) and dynamic response weighting coefficient ζ resp This is used to quantify the ability of a flexible DC converter station to replace traditional reactive power equipment under transient and steady-state operating conditions.

[0046] Based on the preliminary rated capacity of each converter station S nom,i and current active power transmission demand P ref,i ( t ), calculate the converter station at time t i The available reactive power capacity is expressed by formula (10): (10) Indicates the converter station at time t i Available reactive power capacity.

[0047] Because flexible DC-DC interconnects prioritize active power transmission, their reactive power output is time-varying. The equivalent substitution coefficient of this invention... η sub The definition is shown in formula (11): (11) in Q demand ( t ( ) represents the system's reactive power demand curve. ζ resp For dynamic response weighting coefficients, T represents the selected steady-state and transient evaluation integration time period.

[0048] Ultimately, the problem is transformed into finding the optimal rated capacity. S opt Mathematical problems.

[0049] The objective function is shown in formula (12): (12) in, This indicates the solution for the optimal rated capacity. S opt The objective function; B rel To improve efficiency and reliability, C vsc ( S) represents the total cost function of flexible DC interconnection; S represents the capacity variable.

[0050] It can be understood that the above formula (12) has the same meaning as formula (6), except that in formula (12), the final determined capacity S of the flexible DC converter station is used as the independent variable to obtain the maximum value of NBS.

[0051] For the steady-state active power requirement, satisfy S > P max,flow To ensure maximum active power transmission, P max,flow This represents the maximum active power flow transmission demand under the operating scenario of the distribution network; similarly, the minimum dynamic voltage support needs to be provided during transient faults.

[0052] From formula (12) for capacity S Taking the derivative, to satisfy the optimal capacity configuration condition, the following formula (13) should hold according to formula (9): (13) The optimal rated capacity S is finally obtained. opt .

[0053] In this embodiment, the optimal capacity configuration result is obtained by taking the derivative of the comprehensive net benefit function and setting the derivative to zero, thus ensuring that the economic efficiency is optimal while satisfying the constraints of maximum active power transmission and minimum dynamic voltage support.

[0054] This embodiment first inputs the distribution network parameters and establishes a flexible DC interconnection and its... P - Q The coupling characteristic model is then used; subsequently, the dynamic equivalent substitution coefficient of the flexible DC interconnect for the traditional reactive power compensation device is calculated; then, the marginal impact index of active / reactive power regulation on the overall net benefit is calculated, and the balance between the expansion cost of the converter station and the cost savings of traditional equipment is quantified; finally, a nonlinear programming model that takes into account both economy and safety is constructed and solved, and the optimal rated capacity of the converter station and the reactive power compensation device is output.

[0055] Example 2 This embodiment discloses a system for coordinating and optimizing the capacity of flexible DC converter stations and reactive power compensation devices.

[0056] The system for coordinated configuration optimization of flexible DC converter stations and reactive power compensation devices includes: The interconnection modeling module is configured to: acquire the distribution network topology and operating parameters, and construct a flexible DC interconnection model; The constraint establishment module is configured to: establish the constraints of the flexible DC converter station. P - QThe coupling characteristic curves are used to determine the apparent power capacity constraints, power flow constraints, and physical constraints of the power equipment at the flexible DC converter station. The equivalent substitution analysis module is configured to calculate the equivalent substitution coefficient of the flexible DC interconnect for the traditional reactive power compensation device based on the real-time reactive power demand of the system and the dynamic response weight of the flexible DC converter station. The marginal benefit assessment module is configured to: use the marginal cost analysis method to calculate the marginal impact index of active and reactive power regulation demand on the overall net revenue of the system, and determine whether the flexible DC interconnection device alone can meet the reactive power demand of the system based on the marginal impact index. The capacity collaborative optimization module is configured as follows: If the conditions are not met, calculate the reactive power deficit and configure a traditional reactive power compensation device. If the conditions are met, there is no need to configure a traditional reactive power compensation device, and the optimal capacity configuration result of the flexible DC converter station and the reactive power compensation device can be obtained by maximizing the system's optimized net benefit function.

[0057] Those skilled in the art will understand that the modules or steps of the present invention described above can be implemented using general-purpose computer devices. Optionally, they can be implemented using computer-executable program code, thereby allowing them to be stored in a storage device for execution by a computer device, or they can be fabricated as separate integrated circuit modules, or multiple modules or steps can be fabricated as a single integrated circuit module. The present invention is not limited to any particular combination of hardware and software.

[0058] While the specific embodiments of the present invention have been described above in conjunction with the accompanying drawings, this is not intended to limit the scope of protection of the present invention. Those skilled in the art should understand that various modifications or variations that can be made by those skilled in the art without creative effort based on the technical solutions of the present invention are still within the scope of protection of the present invention.

Claims

1. A method for optimizing the capacity coordination of flexible DC converter stations and reactive power compensation devices, characterized in that, Includes the following steps: Obtain the distribution network topology and operating parameters, and construct a flexible DC interconnection model; Building a flexible DC converter station P - Q The coupling characteristic curves are used to determine the apparent power capacity constraints, power flow constraints, and physical constraints of the power equipment at the flexible DC converter station. Based on the real-time reactive power demand of the system and the dynamic response weight of the flexible DC converter station, the equivalent substitution coefficient of the flexible DC interconnection for the traditional reactive power compensation device is calculated. Using marginal cost analysis, the marginal impact index of active and reactive power regulation demand on the overall net revenue of the system is calculated, and the marginal impact index is used to determine whether the reactive power demand of the system can be met by using the flexible DC interconnect device alone. If the conditions are not met, calculate the reactive power deficit and configure a traditional reactive power compensation device. If the conditions are met, there is no need to configure a traditional reactive power compensation device, and the optimal capacity configuration result of the flexible DC converter station and the reactive power compensation device can be obtained by maximizing the system's optimized net benefit function.

2. The method for coordinating and optimizing the capacity configuration of flexible DC converter stations and reactive power compensation devices as described in claim 1, characterized in that, The flexible DC interconnection model consists of two sets of chain-type static synchronous compensators connected to two feeders respectively, and a back-to-back voltage source converter connected between the neutral points of the two sets of chain-type static synchronous compensators.

3. The method for coordinating and optimizing the capacity configuration of flexible DC converter stations and reactive power compensation devices as described in claim 1, characterized in that, The equivalent substitution coefficient of flexible DC-DC interconnection for traditional reactive power compensation devices is calculated using the following formula: ； in, Q demand ( t () represents the system's reactive power demand curve; ζ resp For dynamic response weighting coefficients; η sub The equivalent substitution coefficient; T represents the integral time period for steady-state and transient evaluations; Indicates the converter station at time t i Available reactive power capacity i This indicates the i-th element.

4. The method for coordinating and optimizing the capacity configuration of flexible DC converter stations and reactive power compensation devices as described in claim 1, characterized in that, The marginal impact index of active and reactive power regulation demand on the overall net revenue of the system is calculated, specifically including: By integrating the life-cycle value difference of flexible DC-DC interconnection facilities, the land resource constraint costs based on land shadow prices, and the reliability improvement benefits, the system achieves a comprehensive net benefit. By solving for the Lagrange multipliers corresponding to the system security constraints, the marginal impact index is obtained, which includes the active power adjustment marginal impact index and the reactive power adjustment marginal impact index.

5. The method for coordinating and optimizing the capacity configuration of flexible DC converter stations and reactive power compensation devices as described in claim 4, characterized in that, The land resource constraint cost based on the shadow price of land is specifically: ； in, Costs constrained by land resources; This represents the function that takes the maximum value. β The equivalent land area coefficient per unit capacity; A avail This refers to the available area of ​​the existing site. λ shadow For shadow land prices; The configuration capacity of traditional reactive power compensation equipment that is an equivalent replacement.

6. The method for coordinating and optimizing the capacity configuration of flexible DC converter stations and reactive power compensation devices as described in claim 4, characterized in that, The specific formulas for calculating the marginal impact index of active power regulation and the marginal impact index of reactive power regulation are as follows: ； in, MII P and MII Q These are the active power adjustment marginal impact index and the reactive power adjustment marginal impact index, respectively. λ * P and λ * Q These are the Lagrange multipliers corresponding to the system safety constraints; This represents the required active power regulation capacity under system transient frequency security constraints. This represents the optimal overall net profit value of the system; This indicates the required reactive power regulation capacity under system voltage safety constraints.

7. The method for coordinating and optimizing the capacity configuration of flexible DC converter stations and reactive power compensation devices as described in claim 1, characterized in that, The determination of whether the system's reactive power requirements can be met solely by utilizing the flexible DC interconnect device, based on the marginal impact index, is as follows: Based on the marginal impact index, a multi-dimensional collaborative model that balances economic efficiency and security is constructed. The optimal solution at the convergence of the multidimensional collaborative model is obtained, yielding preliminary results for the capacity configuration of the flexible DC converter station; Based on the preliminary results of the capacity configuration of the flexible DC converter station, it is determined whether the reactive power requirements of the system can be met by using the flexible DC interconnection device alone.

8. The method for coordinating and optimizing the capacity configuration of flexible DC converter stations and reactive power compensation devices as described in claim 3, characterized in that, By maximizing the system's net benefit function, the optimal capacity configuration of the flexible DC converter station and reactive power compensation device is obtained, including: The objective function is determined as follows: ； in To improve efficiency and reliability, C vsc ( S ) represents the total cost function of flexible DC interconnection; Indicates the cost of land resource constraints; S This indicates the configured capacity of the flexible DC converter station; This indicates the optimization of the net profit function; The optimal capacity configuration of the flexible DC converter station and reactive power compensation device is obtained by differentiating the objective function and setting the extreme value condition that makes the derivative zero.

9. The method for coordinating and optimizing the capacity configuration of flexible DC converter stations and reactive power compensation devices as described in claim 4, characterized in that, By calculating the cost differences between the flexible DC-DC solution and the equivalent traditional solution in terms of initial investment, operation and maintenance, and time value of money, the difference in the total life cycle value of the flexible DC-DC interconnection facility is obtained.

10. A system for coordinated configuration optimization of the capacity of a flexible DC converter station and a reactive power compensation device, characterized in that: include: The interconnection modeling module is configured to: acquire the distribution network topology and operating parameters, and construct a flexible DC interconnection model; The constraint establishment module is configured to: establish the constraints of the flexible DC converter station. P - Q The coupling characteristic curves are used to determine the apparent power capacity constraints, power flow constraints, and physical constraints of the power equipment at the flexible DC converter station. The equivalent substitution analysis module is configured to calculate the equivalent substitution coefficient of the flexible DC interconnect for the traditional reactive power compensation device based on the real-time reactive power demand of the system and the dynamic response weight of the flexible DC converter station. The marginal benefit assessment module is configured to: use the marginal cost analysis method to calculate the marginal impact index of active and reactive power regulation demand on the overall net revenue of the system, and determine whether the flexible DC interconnection device alone can meet the reactive power demand of the system based on the marginal impact index. The capacity collaborative optimization module is configured as follows: If the conditions are not met, calculate the reactive power deficit and configure a traditional reactive power compensation device. If the conditions are met, there is no need to configure a traditional reactive power compensation device, and the optimal capacity configuration result of the flexible DC converter station and the reactive power compensation device can be obtained by maximizing the system's optimized net benefit function.

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