Multi-point network construction type converter optimal configuration method capable of meeting synchronous supporting capacity requirement

Abstract

The invention discloses a multi-point networking type converter optimal configuration method capable of meeting a synchronous supporting capability requirement, and relates to the field of power system planning, and the multi-point networking type converter optimal configuration method comprises the following steps: determining a rapid frequency response capability and a frequency modulation performance requirement of a networking converter; establishing an optimal configuration model meeting the requirement of the synchronous supporting capability, and constructing an objective function based on the minimization of the reconstruction cost of the network-constructing converter; and according to performance requirements of the new energy power station, constraint conditions of control parameters of the network-forming converter are set, and optimal parameter configuration is solved through an optimization algorithm based on the optimal configuration model. According to the method, the control parameters of the grid-forming converter are analyzed and coupled, comprehensive parameter constraint conditions are established, it is ensured that the converter can provide stable frequency response and frequency modulation performance while meeting the synchronous supporting capacity of the power grid, and the overall stability and response capacity of the power grid are improved.

Description

Technical Field

[0001] The present invention relates to the field of power system planning, and in particular to a method for optimizing configuration of a multi-point grid-connected converter that meets synchronous support capability requirements. Background Art

[0002] With the large-scale development of intermittent renewable energy power generation represented by wind power and photovoltaic power generation, grid-connected converters are increasingly used in modern power systems. However, the capacity configuration and transformation of converters is crucial. On the one hand, it is necessary to meet the synchronous support capacity requirements of the power system; on the other hand, the economic cost of converter transformation should be considered under the premise of meeting the system performance requirements.

[0003] At present, the research on multi-point grid-connected converters mainly focuses on control, and there is less research on optimal configuration. The traditional configuration is mainly based on experience and simple calculations, which lacks systematicity and easily leads to unreasonable configuration, affecting the dynamic performance of the system and having poor economy.

[0004] In order to optimize the configuration of the networking units reasonably, the equality and inequality constraints for the control parameters are established on the basis of considering the system frequency support capacity requirements; on the basis of considering the converter transformation cost, an objective function with minimizing the transformation cost as the optimization goal is established; and an optimization configuration model for the multi-point networking control unit of new energy stations that meets the grid synchronization support capacity requirements is established.

[0005] Currently, no effective solution has been proposed for the problems in the related technologies. Summary of the invention

[0006] In view of the shortcomings of the prior art, the present invention proposes an optimization configuration method for a multi-point meshed converter that meets the requirements of synchronous support capability, which solves the problem proposed in the above background technology that the research on the existing multi-point meshed converter mainly focuses on control, and there is less research on optimization configuration. The traditional configuration is mainly based on experience and simple calculations, lacks systematicity, and easily leads to unreasonable configuration, affecting the dynamic performance of the system and having poor economy.

[0007] To achieve the above objectives, the present invention is implemented through the following technical solutions:

[0008] A multi-point grid-type converter optimization configuration method that meets the synchronous support capability requirements, the multi-point grid-type converter optimization configuration method comprising the following steps:

[0009] S1. Build a multi-point network unit control architecture and establish an active power-frequency droop formula to determine the fast frequency response capability and frequency modulation performance requirements of the network converter;

[0010] S2. Control parameters of coupled grid-type converters are established to establish an optimal configuration model that meets the requirements of synchronous support capacity, and an objective function based on minimizing the transformation cost of grid-type converters is constructed;

[0011] S3. According to the performance requirements of the new energy power station, the constraints of the control parameters of the grid-connected converter are established, and the optimal parameter configuration is solved through the optimization algorithm based on the optimization configuration model.

[0012] Furthermore, building a multi-point network unit control architecture and establishing an active power-frequency droop formula to determine the fast frequency response capability and frequency modulation performance requirements of the network converter includes the following steps:

[0013] S11. Obtain the control architecture of the multi-point network unit for the new energy power generation unit, energy storage unit, network-building converter, load and power grid;

[0014] S12. Analyze the virtual synchronous generator of the grid-connected converter and establish the active power-frequency droop formula of the new energy power station;

[0015] S13. According to the frequency regulation performance requirements when the power grid frequency is disturbed, the fast frequency response capability of the grid-connected converter is set;

[0016] Among them, the fast frequency response capability includes the primary frequency modulation coefficient, response time and frequency modulation deviation of the grid-connected converter.

[0017] Furthermore, the virtual synchronous generator of the grid-connected converter is analyzed, and the active power-frequency droop formula of the new energy power station is established, which includes the following steps:

[0018] S121. Establishing the active power-frequency droop formula for virtual synchronous generators participating in primary frequency regulation of the power grid;

[0019] S122. By establishing a signal model of a virtual synchronous generator, the influence of the virtual moment of inertia and virtual damping coefficient of the virtual synchronous generator on the overshoot and regulation time of the power system is analyzed.

[0020] Furthermore, the active power-frequency droop formula of the new energy power station is established as:

[0021] Po=(Kpf+D·ω)·Δω+Pref;

[0022] Where P o It is expressed as the theoretical output active power of the grid-connected converter;

[0023] K pf It is represented as the droop control parameter of the grid-connected converter;

[0024] Δω is expressed as the difference between the rated angular frequency and the actual angular frequency;

[0025] D represents the virtual damping coefficient;

[0026] P ref It is expressed as the active power reference value of the grid-connected converter;

[0027] ω is the output angular frequency.

[0028] Furthermore, by establishing a signal model of a virtual synchronous generator, analyzing the influence of the virtual moment of inertia and virtual damping coefficient of the virtual synchronous generator on the overshoot and adjustment time of the power system includes the following steps:

[0029] S1221. Establishing a dynamic equation of the virtual synchronous generator according to the operating characteristics of the virtual synchronous generator;

[0030] S1222. Based on the signal model, establish an active power signal model transfer function of the virtual synchronous generator;

[0031] S1223. Based on the transfer function, determine the natural oscillation angular frequency and damping coefficient of the virtual synchronous generator to evaluate the inertia and damping characteristics of the power system;

[0032] S1224. If the power system is in an under-damped state, based on a preset error band, determine the influence of the virtual moment of inertia and the virtual damping coefficient on the overshoot and adjustment time of the power system.

[0033] Furthermore, the control parameters of the coupled grid-type converter are used to establish an optimal configuration model that meets the requirements of synchronous support capability, and an objective function based on minimizing the transformation cost of the grid-type converter is constructed, including the following steps:

[0034] S21, respectively coupling the active power, droop control parameters, virtual damping coefficient and virtual rotation inertia of multiple grid-type converters to obtain the total active power, total droop control parameters, total virtual damping coefficient and total virtual rotation inertia of all grid-type converters in the power system;

[0035] S22. Based on the total active power, total droop control parameters, total virtual damping coefficient and total virtual moment of inertia of the grid-forming converter, an optimization configuration model that meets the synchronous support capacity requirements is established;

[0036] S23. Based on the optimization configuration model, an objective function is constructed, with minimizing the transformation cost of the grid-connected converter as the optimization configuration goal.

[0037] Furthermore, the formulas for coupling the active power, droop control parameters, virtual damping coefficients and virtual moments of inertia of multiple grid-connected converters are as follows:

[0038]

[0039] Where P n It is expressed as the total active power after all grid-connected converters are coupled;

[0040] K pf It is represented as the total droop control parameter after all grid-connected converters are coupled;

[0041] D represents the total virtual damping coefficient after all grid-type converters are coupled;

[0042] J represents the total virtual moment of inertia after all grid-type converters are coupled;

[0043] n represents the total number of grid-type converters;

[0044] i represents the i-th grid-connected converter.

[0045] Furthermore, the formula for constructing the objective function is:

[0046] min C=(a·P n +b·K pf +c·D·J);

[0047] Where C represents the transformation cost of the grid-connected converter;

[0048] P n It is expressed as the total active power after all grid-connected converters are coupled;

[0049] K pf It is represented as the total droop control parameter after all grid-connected converters are coupled;

[0050] D represents the total virtual damping coefficient after all grid-type converters are coupled;

[0051] J represents the total virtual moment of inertia after all grid-type converters are coupled;

[0052] n represents the total number of grid-connected converters;

[0053] a represents the transformation cost coefficient of active power of grid-connected converter;

[0054] b represents the transformation cost coefficient of the droop control parameters of the grid-connected converter;

[0055] c represents the transformation cost coefficient of the damping inertia of the grid-type converter.

[0056] Furthermore, according to the performance requirements of the new energy power station, the constraints of the control parameters of the grid-connected converter are established, and based on the optimization configuration model, the optimal parameter configuration is solved by the optimization algorithm, including the following steps:

[0057] S31, randomly generating multiple groups of initial transformation capacities, droop control parameters, virtual damping coefficients and virtual moments of inertia through an optimization algorithm;

[0058] S32, bringing the transformation capacity, droop control parameter, virtual damping coefficient and virtual moment of inertia into the objective function to calculate the fitness value;

[0059] S33. Find a solution that satisfies all constraints and has the minimum fitness, and through multiple iterations, obtain the optimal parameter configuration of the network control unit that meets the set goals and constraints in a given search space.

[0060] Furthermore, the constraints of the control parameters of the grid-forming converter include inequality constraints and equality constraints;

[0061] The formula for the inequality constraint is:

[0062]

[0063] D min ≤D≤D max ;

[0064] J min ≤J≤J max ;

[0065] Where ω0 represents the rated angular frequency of the power system;

[0066] Δω is expressed as the difference between the rated angular frequency and the actual angular frequency;

[0067] ΔP e It represents the primary frequency modulation active output demand of the grid-connected converter;

[0068] D max , D min They are respectively represented as the upper and lower limits of the virtual damping coefficient;

[0069] J max , J min They are respectively represented as the upper and lower limits of the virtual moment of inertia;

[0070] The formula for the equality constraint is:

[0071]

[0072] In the formula, P1, P2 and P i They are respectively represented as the active power of the first grid-type converter, the active power of the second grid-type converter and the active power of the i-th grid-type converter;

[0073] k1, k2 and k irepresent the droop control parameters of the first grid-type converter, the droop control parameters of the second grid-type converter, and the droop control parameters of the i-th grid-type converter respectively;

[0074] D1, D2 and D i denote the virtual damping coefficient of the first grid-type converter, the virtual damping coefficient of the second grid-type converter and the virtual damping coefficient of the i-th grid-type converter respectively;

[0075] J1, J2 and J i They respectively represent the virtual moment of inertia of the first grid-type converter, the virtual moment of inertia of the second grid-type converter and the virtual moment of inertia of the i-th grid-type converter.

[0076] The beneficial effects of the present invention are:

[0077] 1. The present invention establishes a control architecture of a multi-point networking unit, combines the active power-frequency droop control strategy of a new energy station, clarifies the system's requirements for fast frequency response and frequency modulation performance, and establishes comprehensive parameter constraints by analyzing and coupling the control parameters of the networking converter. These constraints ensure that the converter can provide stable frequency response and frequency modulation performance while meeting the synchronous support capability of the power grid, which helps to improve the overall stability and responsiveness of the power grid.

[0078] 2. The present invention constructs an optimization configuration model that meets the synchronous support capability of the power grid. The objective function takes minimizing the transformation cost of the converter as the core, and comprehensively considers the transformation costs of the active power, droop control parameters, virtual damping coefficient and virtual moment of inertia of the grid-forming converter. It not only meets the requirements of system stability and performance, but also greatly reduces the transformation cost of the converter, achieving dual optimization of technology and economy. The optimization algorithm is applied to solve the model, which can quickly find the optimal control parameter configuration, so that multiple grid-forming converters have good synchronous support and load distribution capabilities when operating in parallel. In practical applications, the optimal parameter configuration scheme ensures the rapid response capability of the new energy station when the grid frequency fluctuates, so that the new energy power generation system can effectively participate in the frequency regulation of the grid, thereby improving the stability and reliability of the system.

[0079] 3. The present invention can effectively operate the inverter after optimized configuration within the frequency response dead zone of new energy stations (such as wind power and photovoltaic power stations), thereby enhancing the dynamic performance of the system. By meeting the regulation requirements of the power grid frequency response limit, the present invention improves the frequency regulation effect of the new energy station in the power grid, enhances the adaptability and support capacity of the new energy to the power grid, and provides a guarantee for large-scale new energy access to the power grid. BRIEF DESCRIPTION OF THE DRAWINGS

[0080] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. 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 paying creative work.

[0081] Figure 1 is a flow chart of a method for optimizing configuration of a multi-point grid-connected converter that meets synchronization support capability requirements according to an embodiment of the present invention;

[0082] Figure 2 It is a control architecture diagram of a networking control unit in a multi-point networking type converter optimization configuration method that meets synchronization support capability requirements according to an embodiment of the present invention;

[0083] Figure 3 is a schematic diagram of active power-frequency droop characteristics of a photovoltaic power station with fast frequency response according to an embodiment of the present invention;

[0084] Figure 4 is a schematic diagram of active power-frequency droop characteristics of a wind farm with fast frequency response according to an embodiment of the present invention;

[0085] Figure 5 4 is a block diagram of active power-frequency control of a virtual synchronous generator according to an embodiment of the present invention. DETAILED DESCRIPTION

[0086] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0087] In the description of the present invention, unless otherwise specified, the meaning of "plurality" is two or more. In addition, the terms "first", "second", "third", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0088] According to an embodiment of the present invention, a method for optimizing configuration of a multi-point grid-connected converter that meets synchronization support capability requirements is provided.

[0089] The present invention is further described with reference to the accompanying drawings and specific embodiments. Figure 1 As shown, according to an embodiment of the present invention, a multi-point meshed converter optimization configuration method that meets the synchronization support capability requirement includes the following steps:

[0090] S1. Build a multi-point network unit control architecture and establish an active power-frequency droop formula to determine the fast frequency response capability and frequency modulation performance requirements of the network converter;

[0091] It needs to be explained that the control architecture of the multi-point grid-forming unit is built by taking into account the new energy power generation unit, energy storage unit, grid-forming inverter, load and grid; the control strategy of the grid-forming inverter is analyzed through new energy, and the active power-frequency droop formula of the new energy power station is established; according to the performance requirements such as the primary frequency modulation coefficient, response time, adjustment time and response deviation of the new energy station in response to the grid frequency change when the grid is disturbed, the rapid frequency response capability of the grid-forming control unit is determined.

[0092] Specifically, the control strategy refers to Virtual Synchronous Generator (VSG) control.

[0093] S2. Control parameters of coupled grid-type converters are established to establish an optimal configuration model that meets the requirements of synchronous support capacity, and an objective function based on minimizing the transformation cost of grid-type converters is constructed;

[0094] It needs to be explained that the droop control parameters, virtual damping coefficients and virtual moments of inertia of multiple grid-connected converters are coupled; and on the premise of meeting the synchronous support capacity requirements of the power system, an objective function based on minimizing the converter transformation cost is established.

[0095] It needs to be explained that the demand for synchronous support capacity is mainly the demand for primary frequency regulation support capacity; if the configured parameters can meet the set constraints, then when the power system suffers a frequency disturbance, the new energy stations that have undergone grid construction and transformation can actively adjust the output active power to maintain the stability of the power system frequency.

[0096] S3. According to the performance requirements of the new energy power station, the constraints of the control parameters of the grid-connected converter are established, and the optimal parameter configuration is solved through the optimization algorithm based on the optimization configuration model.

[0097] It needs to be explained that according to the performance requirements of the new energy power station, the inequalities and equality constraints of the droop control parameters, virtual damping coefficient and virtual moment of inertia of the grid-connected converter are established; the proposed model is optimized and solved through the optimization algorithm to obtain the optimal parameter configuration of the grid-connected control unit.

[0098] It should be explained that the performance requirements refer to the fast frequency response requirements of new energy stations, which specifically include:

[0099] 1) The VSG active frequency modulation start-up time is no more than 100ms;

[0100] 2) The VSG active frequency regulation time is no more than 1s;

[0101] 3) The maximum value of the active power regulation of VSG participating in primary frequency regulation should not be less than 10% of the rated power.

[0102] Preferably, building a multi-point network unit control architecture and establishing an active power-frequency droop formula to determine the fast frequency response capability and frequency modulation performance requirements of the network converter includes the following steps:

[0103] S11. Obtain the control architecture of the multi-point network unit for the new energy power generation unit, energy storage unit, network-building converter, load and power grid;

[0104] It should be explained that the control architecture of the network control unit is as follows Figure 2 As shown in the figure, it consists of a new energy power generation unit, an energy storage unit, a converter, a load and a power grid. By equipping the grid-connected side of the new energy inverter with an energy storage module of a certain capacity, the entire power system has a primary frequency regulation control function. In the case of frequency fluctuations on the grid or load side and fluctuations in the output of new energy, the energy storage regulation module compensates for the power demand of the power system. New energy stations, especially wind and solar power stations, need to provide grid synchronization support capabilities through a network control unit to ensure dynamic response when the grid frequency fluctuates and meet the needs of rapid frequency response.

[0105] It needs to be explained that the energy storage module refers to battery energy storage. After a certain capacity of energy storage is configured on the DC side, when the frequency of the grid-connected point crosses the frequency modulation dead zone, the active power target value is calculated according to the active power-frequency droop characteristics of the VSG, and the control instructions are distributed and issued to the DC / DC converter connected to the energy storage system according to the active power control strategy. By adjusting the duty cycle, the voltage and current of the energy storage battery are changed, the output power is changed, and the primary frequency modulation function is realized.

[0106] It needs to be explained that Figure 3-Figure 4 As shown, 49.94Hz~50.06Hz is the non-effective area of ​​the fast frequency response of the photovoltaic power station, and 49.8Hz and 50.2Hz are the fast frequency response limits of the photovoltaic power station; 49.9Hz~50.1Hz is the non-effective area of ​​the fast frequency response of the wind farm, and 49.8Hz and 50.2Hz are the fast frequency response limits of the wind farm. In the power system, Pn refers to the rated active power after all grid-connected converters are coupled, and P (MW) refers to the actual output active power.

[0107] S12. Analyze the virtual synchronous generator of the grid-connected converter and establish the active power-frequency droop formula of the new energy power station;

[0108] S13. According to the frequency regulation performance requirements when the power grid frequency is disturbed, the fast frequency response capability of the grid-connected converter is set;

[0109] Among them, the fast frequency response capability includes the primary frequency modulation coefficient, response time and frequency modulation deviation of the grid-connected converter.

[0110] Preferably, analyzing the virtual synchronous generator of the grid-connected converter and establishing the active power-frequency droop formula of the new energy power station includes the following steps:

[0111] S121. Establishing the active power-frequency droop formula for virtual synchronous generators participating in primary frequency regulation of the power grid;

[0112] It needs to be explained that the active power-frequency droop formula for establishing a virtual synchronous generator to participate in the primary frequency regulation of the power grid is:

[0113] Pm=Kpf·Δω+Pref;

[0114] Where P m It is expressed as the theoretical output active power of the grid-connected converter;

[0115] K pf It is represented as the droop control parameter of the grid-connected converter;

[0116] Δω is expressed as the difference between the rated angular frequency and the actual angular frequency;

[0117] P ref It is expressed as the active power reference value of the grid-connected converter.

[0118] S122. By establishing a signal model of a virtual synchronous generator, the influence of the virtual moment of inertia and virtual damping coefficient of the virtual synchronous generator on the overshoot and regulation time of the power system is analyzed.

[0119] Preferably, the active power-frequency droop formula of the new energy power station is established as:

[0120] Po=(Kpf+D·ω)·Δω+Pref;

[0121] Where P o It is expressed as the theoretical output active power of the new energy power station;

[0122] K pf It is represented as the droop control parameter of the grid-connected converter;

[0123] Δω is expressed as the difference between the rated angular frequency and the actual angular frequency;

[0124] D represents the virtual damping coefficient;

[0125] P ref It is expressed as the active power reference value of the grid-connected converter;

[0126] ω is the output angular frequency.

[0127] Preferably, by establishing a signal model of a virtual synchronous generator, analyzing the influence of the virtual moment of inertia and virtual damping coefficient of the virtual synchronous generator on the overshoot and adjustment time of the power system includes the following steps:

[0128] S1221. Establishing a dynamic equation of the virtual synchronous generator according to the operating characteristics of the virtual synchronous generator;

[0129] It should be explained that since the grid-type converter adopts the control method of VSG, the synchronous support capability of the grid-type converter is analyzed through the rotor motion equation of VSG, which reflects the inertia and damping characteristics of VSG. The rotor motion equation of VSG is:

[0130]

[0131] Where, J represents the virtual moment of inertia;

[0132] D represents the virtual damping coefficient;

[0133] ω0 is expressed as the rated angular frequency;

[0134] ω is the output angular frequency;

[0135] P m It is expressed as the theoretical output active power of the grid-connected converter;

[0136] P e It is expressed as the output active power of the grid-connected converter.

[0137] S1222. Based on the signal model, establish an active power signal model transfer function of the virtual synchronous generator;

[0138] It should be explained that the formula for establishing the transfer function is:

[0139]

[0140] Where, J represents the virtual moment of inertia;

[0141] D represents the virtual damping coefficient;

[0142] E represents the output voltage of VSG;

[0143] U represents the grid voltage;

[0144] Z represents the line impedance;

[0145] ω0 is expressed as the rated angular frequency;

[0146] K pf It is represented as the droop control parameter of the grid-connected converter;

[0147] G(s) is represented as a transfer function.

[0148] S1223. Based on the transfer function, determine the natural oscillation angular frequency and damping coefficient of the virtual synchronous generator to evaluate the inertia and damping characteristics of the power system;

[0149] It should be explained that the formula for obtaining the natural oscillation angular frequency and damping coefficient of the corresponding second-order model according to the transfer function is:

[0150]

[0151] In the formula, ω n Expressed as the natural oscillation angular frequency;

[0152] ξ is the damping coefficient;

[0153] J represents the virtual moment of inertia;

[0154] D represents the virtual damping coefficient;

[0155] E represents the output voltage of VSG;

[0156] U represents the grid voltage;

[0157] Z represents the line impedance;

[0158] ω0 is represented as the rated angular frequency.

[0159] S1224. If the power system is in an under-damped state, based on a preset error band, determine the influence of the virtual moment of inertia and the virtual damping coefficient on the overshoot and adjustment time of the power system.

[0160] It should be explained that, assuming that the system is in an underdamped state and the error band Δ=2%, the overshoot and adjustment time of the system are:

[0161]

[0162] In the formula, σ% represents the overshoot;

[0163] t s It is expressed as adjustment time;

[0164] J represents the virtual moment of inertia;

[0165] K pf It is represented as the droop control parameter of the grid-connected converter;

[0166] ω0 is expressed as the rated angular frequency;

[0167] e represents a natural constant, and its value is approximately 2.718.

[0168] Preferably, coupling the control parameters of the grid-forming converter, establishing an optimization configuration model that meets the synchronization support capability requirements, and constructing an objective function based on minimizing the transformation cost of the grid-forming converter include the following steps:

[0169] S21, respectively coupling the active power, droop control parameters, virtual damping coefficient and virtual rotation inertia of multiple grid-type converters to obtain the total active power, total droop control parameters, total virtual damping coefficient and total virtual rotation inertia of all grid-type converters in the power system;

[0170] S22. Based on the total active power, total droop control parameters, total virtual damping coefficient and total virtual moment of inertia of the grid-forming converter, an optimization configuration model that meets the synchronous support capacity requirements is established;

[0171] S23. Based on the optimization configuration model, an objective function is constructed, with minimizing the transformation cost of the grid-connected converter as the optimization configuration goal.

[0172] Preferably, the formula for coupling the active power, droop control parameter, virtual damping coefficient and virtual moment of inertia of multiple grid-connected converters is:

[0173]

[0174] Where P n It is expressed as the total active power after all grid-connected converters are coupled;

[0175] K pf It is represented as the total droop control parameter after all grid-connected converters are coupled;

[0176] D represents the total virtual damping coefficient after all grid-type converters are coupled;

[0177] J represents the total virtual moment of inertia after all grid-type converters are coupled;

[0178] n represents the total number of grid-connected converters;

[0179] i represents the i-th grid-connected converter.

[0180] Preferably, the formula for constructing the objective function is:

[0181] min C=(a·P n +b·K pf +c·D·J);

[0182] Where C represents the transformation cost of the grid-connected converter;

[0183] P n It is expressed as the total active power after all grid-connected converters are coupled;

[0184] K pf It is represented as the total droop control parameter after all grid-connected converters are coupled;

[0185] D represents the total virtual damping coefficient after all grid-type converters are coupled;

[0186] J represents the total virtual moment of inertia after all grid-type converters are coupled;

[0187] n represents the total number of grid-connected converters;

[0188] a represents the transformation cost coefficient of active power of grid-connected converter;

[0189] b represents the transformation cost coefficient of the droop control parameters of the grid-connected converter;

[0190] c represents the transformation cost coefficient of the damping inertia of the grid-type converter.

[0191] Specifically, the damping inertia refers to a virtual damping coefficient and a virtual rotational inertia.

[0192] Preferably, according to the performance requirements of the new energy power station, the constraints of the control parameters of the grid-connected converter are established, and based on the optimization configuration model, the optimal parameter configuration is solved by the optimization algorithm, including the following steps:

[0193] S31, randomly generating multiple groups of initial transformation capacity (i.e., active power), droop control parameters, virtual damping coefficients, and virtual moments of inertia through an optimization algorithm;

[0194] S32, bringing the transformation capacity, droop control parameter, virtual damping coefficient and virtual moment of inertia into the objective function to calculate the fitness value;

[0195] S33. Find a solution that satisfies all constraints and has the minimum fitness, and through multiple iterations, obtain the optimal parameter configuration of the network control unit that meets the set goals and constraints in a given search space.

[0196] Preferably, the constraints of the control parameters of the grid-connected converter include inequality constraints and equality constraints;

[0197] The formula for the inequality constraint is:

[0198]

[0199] D min ≤D≤D max ;

[0200] J min ≤J≤J max ;

[0201] Where ω0 represents the rated angular frequency of the power system;

[0202] Δω is expressed as the difference between the rated angular frequency and the actual angular frequency;

[0203] ΔP e It represents the primary frequency modulation active output demand of the grid-connected converter;

[0204] D max , D min They are respectively represented as the upper and lower limits of the virtual damping coefficient;

[0205] J max , J min They are respectively represented as the upper and lower limits of the virtual moment of inertia;

[0206] The formula for the equality constraint is:

[0207]

[0208] In the formula, P1, P2 and P i They are respectively represented as the active power of the first grid-type converter, the active power of the second grid-type converter and the active power of the i-th grid-type converter;

[0209] k1, k2 and k i represent the droop control parameters of the first grid-type converter, the droop control parameters of the second grid-type converter, and the droop control parameters of the i-th grid-type converter respectively;

[0210] D1, D2 and D i denote the virtual damping coefficient of the first grid-type converter, the virtual damping coefficient of the second grid-type converter and the virtual damping coefficient of the i-th grid-type converter respectively;

[0211] J1, J2 and J i They respectively represent the virtual moment of inertia of the first grid-type converter, the virtual moment of inertia of the second grid-type converter and the virtual moment of inertia of the i-th grid-type converter.

[0212] It should be explained that when grid-connected converters of different capacities are connected in parallel, in order to reasonably distribute power among the converters, it is necessary to analyze the parameter setting principles when multiple converters of different capacities are connected in parallel. Figure 5 As shown, the frequency deviation is 0 in steady state, and the configuration principles of J1, J2 and D1, D2 in the system are as follows:

[0213]

[0214] Wherein, J1 and J2 represent the virtual moment of inertia of the first grid-type converter and the virtual moment of inertia of the second grid-type converter, respectively;

[0215] D1 and D2 represent the virtual damping coefficient of the first grid-type converter and the virtual damping coefficient of the second grid-type converter, respectively.

[0216] It should be explained that m is just a ratio, which means that the ratio of the current formula is the same as that of the following formula.

[0217] When the capacities of the two converters are set in proportion, it is obvious that their output active power should also be distributed in the same proportional relationship. On the other hand, according to the active power-frequency expression, the proportional relationship of active power and the active power droop formula are combined to obtain:

[0218]

[0219] Wherein, P1 and P2 represent the active power of the first grid-connected converter and the active power of the second grid-connected converter respectively;

[0220] k1 and k2 represent the droop control parameters of the first grid-type converter and the second grid-type converter, respectively;

[0221] Δω is expressed as the difference between the rated angular frequency and the actual angular frequency;

[0222] P ref1 , P ref2 They are respectively represented as the active power reference value of the first grid-connected converter and the active power reference value of the second grid-connected converter.

[0223] Since the angular frequencies of the converters are consistent, the configuration principles of the droop control parameters k1 and k2 in the system are as follows:

[0224]

[0225] Wherein, k1 and k2 represent the droop control parameters of the first grid-connected converter and the second grid-connected converter, respectively.

[0226] According to the above analysis, in order to make each converter perform reasonable power distribution and have better operating characteristics, the equality constraint conditions of the network control parameters are established.

[0227] In summary, with the help of the above technical scheme of the present invention, the present invention constructs an optimization configuration model that meets the synchronous support capability of the power grid. The objective function takes the minimization of the transformation cost of the converter as the core, comprehensively considers the transformation cost of the active power, droop control parameters, virtual damping coefficient and virtual moment of inertia of the grid-type converter, not only meets the requirements of system stability and performance, but also greatly reduces the transformation cost of the converter, and realizes the dual optimization of technology and economy. The optimization algorithm is applied to solve the model, and the optimal control parameter configuration can be quickly found, so that multiple grid-type converters have good synchronous support and load distribution capabilities when running in parallel. The optimal parameter configuration scheme ensures the rapid response capability of the new energy station when the power grid frequency fluctuates in practical applications, so that the new energy power generation system can effectively participate in the frequency regulation of the power grid, and improves the stability and reliability of the system. The converter after the optimized configuration of the present invention can effectively work within the frequency response dead zone of the new energy station (such as wind power and photovoltaic power stations), enhances the dynamic performance of the system, and by meeting the regulation requirements of the power grid frequency response limit, the present invention improves the frequency modulation effect of the new energy station in the power grid, enhances the power grid adaptability and support capability of new energy, and provides a guarantee for large-scale new energy access to the power grid.

[0228] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A multi-point grid-type converter optimization configuration method that meets the requirements of synchronous support capability, characterized in that: The multi-point grid-type converter optimization configuration method comprises the following steps: S1. Build a multi-point network unit control architecture and establish an active power-frequency droop formula to determine the fast frequency response capability and frequency modulation performance requirements of the network converter; S2. Control parameters of coupled grid-type converters are established to establish an optimal configuration model that meets the requirements of synchronous support capacity, and an objective function based on minimizing the transformation cost of grid-type converters is constructed; S3. According to the performance requirements of the new energy power station, the constraints of the control parameters of the grid-connected converter are established, and the optimal parameter configuration is solved through the optimization algorithm based on the optimization configuration model.

2. The multi-point grid-type converter optimization configuration method that meets the synchronous support capability requirements according to claim 1 is characterized in that: The construction of a multi-point network unit control architecture and the establishment of an active power-frequency droop formula to determine the fast frequency response capability and frequency modulation performance requirements of the network converter include the following steps: S11. Obtain the control architecture of the multi-point network unit for the new energy power generation unit, energy storage unit, network-building converter, load and power grid; S12. Analyze the virtual synchronous generator of the grid-connected converter and establish the active power-frequency droop formula of the new energy power station; S13. According to the frequency regulation performance requirements when the power grid frequency is disturbed, the fast frequency response capability of the grid-connected converter is set; Among them, the fast frequency response capability includes the primary frequency modulation coefficient, response time and frequency modulation deviation of the grid-connected converter.

3. The method for optimizing configuration of multi-point grid-connected converters that meets the synchronous support capability requirement according to claim 2, characterized in that: The analysis of the virtual synchronous generator of the grid-connected converter and the establishment of the active power-frequency droop formula of the new energy power station include the following steps: S121. Establishing the active power-frequency droop formula for virtual synchronous generators participating in primary frequency regulation of the power grid; S122. By establishing a signal model of a virtual synchronous generator, the influence of the virtual moment of inertia and virtual damping coefficient of the virtual synchronous generator on the overshoot and regulation time of the power system is analyzed.

4. The method for optimizing configuration of multi-point grid-connected converters that meets the synchronous support capability requirement according to claim 3, characterized in that: The formula for establishing the active power-frequency droop of the new energy power station is: Po=(Kpf+D·ω)·Δω+Pref; Where P o It is expressed as the theoretical output active power of the grid-connected converter; K pf It is represented as the droop control parameter of the grid-connected converter; Δω is expressed as the difference between the rated angular frequency and the actual angular frequency; D represents the virtual damping coefficient; P ref It is expressed as the active power reference value of the grid-connected converter; ω is the output angular frequency.

5. The method for optimizing configuration of multi-point grid-connected converters that meets the synchronous support capability requirement according to claim 4, characterized in that: The method of establishing a signal model of a virtual synchronous generator and analyzing the influence of the virtual moment of inertia and the virtual damping coefficient of the virtual synchronous generator on the overshoot and adjustment time of the power system comprises the following steps: S1221. Establishing a dynamic equation of the virtual synchronous generator according to the operating characteristics of the virtual synchronous generator; S1222. Based on the signal model, establish an active power signal model transfer function of the virtual synchronous generator; S1223. Based on the transfer function, determine the natural oscillation angular frequency and damping coefficient of the virtual synchronous generator to evaluate the inertia and damping characteristics of the power system; S1224. If the power system is in an under-damped state, based on a preset error band, determine the influence of the virtual moment of inertia and the virtual damping coefficient on the overshoot and adjustment time of the power system.

6. The method for optimizing configuration of multi-point grid-connected converters that meets the synchronous support capability requirement according to claim 1, characterized in that: The control parameters of the coupled grid-type converter are established to establish an optimal configuration model that meets the requirements of synchronous support capability, and to construct an objective function based on minimizing the transformation cost of the grid-type converter, including the following steps: S21, respectively coupling the active power, droop control parameters, virtual damping coefficient and virtual rotation inertia of multiple grid-type converters to obtain the total active power, total droop control parameters, total virtual damping coefficient and total virtual rotation inertia of all grid-type converters in the power system; S22. Based on the total active power, total droop control parameters, total virtual damping coefficient and total virtual moment of inertia of the grid-forming converter, an optimization configuration model that meets the synchronous support capacity requirements is established; S23. Based on the optimization configuration model, an objective function is constructed, with minimizing the transformation cost of the grid-connected converter as the optimization configuration goal.

7. The method for optimizing configuration of multi-point grid-connected converters that meets the synchronous support capability requirement according to claim 6, characterized in that: The formula for coupling the active power, droop control parameter, virtual damping coefficient and virtual moment of inertia of multiple grid-connected converters is: Where P n It is expressed as the total active power after all grid-connected converters are coupled; K pf It is represented as the total droop control parameter after all grid-connected converters are coupled; D represents the total virtual damping coefficient after all grid-type converters are coupled; J represents the total virtual moment of inertia after all grid-type converters are coupled; n represents the total number of grid-type converters; i represents the i-th grid-connected converter.

8. The method for optimizing configuration of multi-point grid-connected converters that meets the synchronous support capability requirement according to claim 7, characterized in that: The formula for constructing the objective function is: min C=(a·P n +b·K pf +c·D·J); Where C represents the transformation cost of the grid-connected converter; P n It is expressed as the total active power after all grid-connected converters are coupled; K pf It is represented as the total droop control parameter after all grid-connected converters are coupled; D represents the total virtual damping coefficient after all grid-type converters are coupled; J represents the total virtual moment of inertia after all grid-type converters are coupled; n represents the total number of grid-type converters; a represents the transformation cost coefficient of active power of grid-connected converter; b represents the transformation cost coefficient of the droop control parameters of the grid-connected converter; c represents the transformation cost coefficient of the damping inertia of the grid-type converter.

9. The method for optimizing configuration of multi-point grid-connected converters that meets the synchronous support capability requirement according to claim 1, characterized in that: According to the performance requirements of the new energy power station, setting the constraints of the control parameters of the grid-connected converter, and solving the optimal parameter configuration through the optimization algorithm based on the optimization configuration model includes the following steps: S31, randomly generating multiple groups of initial transformation capacities, droop control parameters, virtual damping coefficients and virtual moments of inertia through an optimization algorithm; S32, bringing the transformation capacity, droop control parameter, virtual damping coefficient and virtual moment of inertia into the objective function to calculate the fitness value; S33. Find a solution that satisfies all constraints and has the minimum fitness, and through multiple iterations, obtain the optimal parameter configuration of the network control unit that meets the set goals and constraints in a given search space.

10. The method for optimizing configuration of multi-point grid-connected converters that meets the synchronous support capability requirement according to claim 9, characterized in that: The constraints of the control parameters of the grid-connected converter include inequality constraints and equality constraints; The formula for the inequality constraint is: D min ≤D≤D max ; J min ≤J≤J max ; Where ω0 represents the rated angular frequency of the power system; Δω is expressed as the difference between the rated angular frequency and the actual angular frequency; ΔP e It represents the primary frequency modulation active output demand of the grid-connected converter; D max , D min They are respectively represented as the upper and lower limits of the virtual damping coefficient; J max , J min They are respectively represented as the upper and lower limits of the virtual moment of inertia; The formula for the equality constraint is: In the formula, P1, P2 and P i They are respectively represented as the active power of the first grid-type converter, the active power of the second grid-type converter and the active power of the i-th grid-type converter; k1, k2 and k i represent the droop control parameters of the first grid-type converter, the droop control parameters of the second grid-type converter, and the droop control parameters of the i-th grid-type converter respectively; D1, D2 and D i denote the virtual damping coefficient of the first grid-type converter, the virtual damping coefficient of the second grid-type converter and the virtual damping coefficient of the i-th grid-type converter respectively; J1, J2 and J i They respectively represent the virtual moment of inertia of the first grid-type converter, the virtual moment of inertia of the second grid-type converter and the virtual moment of inertia of the i-th grid-type converter.

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