Voltage source type energy storage and new energy collaborative active grid-connected operation method and system

Abstract

The invention discloses a voltage source type energy storage and new energy collaborative active grid-connected operation method and system, and belongs to the technical field of grid connection. The method comprises the steps that new energy grid-connected node parameters are acquired, and a voltage source type energy storage power station / new energy hybrid power system Thevenin equivalent circuit is constructed; according to a Thevenin equivalent circuit of the voltage source type energy storage power station / new energy hybrid power system, static stability limits of output power of different new energy power stations are calculated; based on the static stability limit, constructing a relationship between virtual impedance and reactive output of the energy storage system when new energy output approaches the static limit; based on the relation between virtual impedance and reactive power output of an energy storage system, for a new energy power station with low static operation margin, virtual impedance parameters and reactive power output values of a matched voltage source type energy storage power station are changed, so that the stability limit of new energy grid-connected operation is improved. The method not only can improve the stability and adaptability of the system, but also can optimize the economical efficiency of the system and promote the wide application of new energy.

Description

Technical Field

[0001] The present invention proposes a method and system for active grid connection in coordination with voltage source energy storage and new energy, belonging to the technical field of grid connection. Background Art

[0002] A high proportion of new energy power systems is the trend of future development. New energy usually uses current source inverters to connect to the grid and needs sufficient voltage support from the grid. With the continuous grid connection of large-scale new energy, the operation characteristics of the power grid have changed, especially the problem of voltage stability has gradually become prominent. The current tolerance of the power converter in the new energy is not high, and it cannot provide sufficient fault current when the new energy station fails. The large-scale grid connection of new energy will reduce the new energy multi-station short-circuit ratio (MRSCR) and cannot actively support the grid. With the development of new energy and energy storage technology, in order to provide sufficient voltage source support, the inverter network control technology will be the future development trend.

[0003] With the rapid development of energy internet and renewable energy, in order to solve the bottleneck problem of transmission and consumption of new energy power generation, large-scale energy storage is often required to participate in the cluster control and dispatching operation of new energy power generation. The voltage source control adopted by new energy stations has strong adaptability to weak power grids, but the random volatility of wind power and photovoltaics makes it difficult to build a stable voltage / frequency. Energy storage has stable power supply support conditions and is suitable for voltage source control, which is conducive to improving the adaptability of new energy stations to weak power grids. In addition, although some new energy stations are equipped with energy storage, they have not fully played their active supporting role for the power grid. Therefore, it is urgent to carry out research on voltage source energy storage to improve the adaptability of new energy stations to weak power grids, and provide theoretical support and engineering practice for the safe grid connection and operation of large-scale new energy power generation. Summary of the invention

[0004] In view of the shortcomings of the prior art, the present invention provides a method and system for active grid-connected operation of voltage source energy storage and new energy. The method can not only improve the stability and adaptability of the system, but also optimize the economy of the system and promote the widespread application of new energy.

[0005] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0006] In a first aspect, the present invention provides a method for active grid-connected operation of voltage source energy storage and new energy in coordination, comprising:

[0007] Obtain the parameters of the new energy grid-connected nodes and construct the Thevenin equivalent circuit of the voltage source energy storage power station / new energy hybrid power system;

[0008] According to the Thevenin equivalent circuit of the voltage source energy storage power station / new energy hybrid power system, the static stability limit of the output power of different new energy power stations is calculated;

[0009] Based on the static stability limit, the relationship between the virtual impedance and reactive output of the energy storage system is constructed when the output of new energy approaches the static limit;

[0010] Based on the relationship between the virtual impedance and reactive output of the energy storage system, for new energy power stations with low static operation margin, the virtual impedance parameters and reactive output values ​​of their supporting voltage source energy storage power stations are changed to improve the stability limit of new energy grid-connected operation.

[0011] As a further improvement of the present invention, the method of obtaining the parameters of the new energy grid-connected node and constructing the Thevenin equivalent circuit of the voltage source energy storage power station / new energy hybrid power system includes:

[0012] Obtain new energy grid-connected node parameters, including: voltage, current, frequency, and impedance;

[0013] Assume that the current injected into the AC system by each renewable energy grid-connected bus is Then the voltage of each grid-connected bus node Expressed as

[0014]

[0015] In the formula, is the AC grid equivalent impedance matrix Z at the new energy grid-connected busbar eq The i-th row and j-th column element of

[0016] The short-circuit ratio MRSCR of the new energy multi-station at the i-th new energy grid-connected busbar is:

[0017]

[0018] Where: is the nominal voltage of the i-th grid-connected bus node; is the voltage generated by the power generated by the new energy equipment at the i-th node, and the subscript RE represents the new energy power generation equipment / station; is the short-circuit current provided by the i-th renewable energy power generation equipment / station; let the actual operating voltage of the i-th grid-connected bus node be

[0019] Based on the equivalent circuit of voltage source energy storage power station / new energy hybrid power system, a multi-port Thevenin equivalent circuit is constructed:

[0020] After node 1 is connected to the energy storage, it is equivalent to connecting the ground branch z0 in parallel at node 1; after the energy storage is connected to node 1, the equivalent impedance matrix Z eq becomes the equivalent node impedance matrix Z e ' q , whose expression is

[0021]

[0022] Where: is the transpose of Z1, Z1 is the equivalent impedance matrix Z eq The first row vector of , z0 is the equivalent impedance of the grid-type energy storage;

[0023] Z eq After expansion, the formula for any element is as follows:

[0024]

[0025] In the formula, is the AC grid equivalent impedance matrix Z at the new energy grid-connected busbar eq is the i-th row and j-th column element of ; z0 is the equivalent impedance of the grid-type energy storage.

[0026] As a further improvement of the present invention, the calculation of the static stability limit of the output power of different renewable energy power stations includes calculating the static limit current and the static limit power angle of the renewable energy grid-connected node.

[0027] As a further improvement of the present invention, the static stability limit of the output power of different new energy power stations is calculated according to the Thevenin equivalent circuit of the voltage source energy storage power station / new energy hybrid power system; including:

[0028] The grid-connected converter output voltage vector is U t ∠0;X g is the equivalent inductance L between the grid-connected converter and the grid g The fundamental wave equivalent impedance of the grid voltage vector is U g ∠-δ t , then the voltage amplitude of the grid-connected node of the new energy grid-connected converter is U t The expression is:

[0029]

[0030] Active power exchanged between the new energy grid-connected converter and the infinite power grid:

[0031]

[0032] Calculate the d-axis current I d With phase angle δ t The relationship between:

[0033] I d X g =U g sinδ t

[0034] Get P out With δ t The relationship between:

[0035]

[0036] On the AC side under weak grid conditions, the grid base frequency impedance X g , the corresponding maximum transmittable active power is

[0037]

[0038] When I q = 0, find

[0039]

[0040] When I q =0 when the static limiting current I d_cr With SCR, rated current I d_rated The relationship is

[0041]

[0042] Where U g is the grid voltage vector amplitude; X g is the equivalent inductance L between the grid-connected converter and the grid g The fundamental wave equivalent impedance; SCR is the short circuit ratio; I d_rated is the rated current.

[0043] As a further improvement of the present invention, the relationship between the virtual impedance and reactive output of the energy storage system when the output of new energy approaches the static limit is constructed, including:

[0044] The voltage generated by the virtual impedance is added as feedback to the output of the droop link to generate a new reference voltage. The virtual impedance is expressed as:

[0045]

[0046] Among them, R v is the virtual resistance component, L v is the virtual inductance component;

[0047] After adding the virtual impedance control loop, the output voltage expression of the inverter is:

[0048] U0(s)=G(s)U ref -(G(s)Z v (s)+Z0(s))I0(s)

[0049] G(s) is the voltage closed-loop transfer function of the inverter, and Z0(s) is the inverter output impedance.

[0050] As a further improvement of the present invention, for a new energy power station with low static operation margin, the virtual impedance parameters and reactive output value of its supporting voltage source energy storage power station are changed to improve the stability limit of the new energy grid-connected operation, including:

[0051] When a new energy source fails and its output approaches the static limit, the energy storage system’s virtual resistance and reactive output are increased to actively support the grid;

[0052] When the fault of the new energy source is eliminated, the virtual impedance of the energy storage system is reduced when the output static limit margin is large.

[0053] As a further improvement of the present invention, the increasing of the virtual impedance and reactive output of the energy storage system refers to increasing the short-circuit ratio of the system when the short-circuit ratio decreases due to a fault in the power grid, so as to actively support the power grid.

[0054] In a second aspect, the present invention provides a voltage source type energy storage and new energy coordinated active grid-connected operation system, comprising:

[0055] The acquisition module is used to obtain the parameters of the new energy grid-connected nodes and construct the Thevenin equivalent circuit of the voltage source energy storage power station / new energy hybrid power system;

[0056] A calculation module, used to calculate the static stability limit of the output power of different renewable energy power stations based on the Thevenin equivalent circuit of the voltage source energy storage power station / new energy hybrid power system;

[0057] A construction module is used to construct the relationship between the virtual impedance and reactive output of the energy storage system when the output of new energy is close to the static limit based on the static stability limit;

[0058] The improvement module is used to change the virtual impedance parameters and reactive output values ​​of the supporting voltage source energy storage power station based on the relationship between the virtual impedance and reactive output of the energy storage system, for new energy power stations with low static operation margin, so as to improve the stability limit of new energy grid-connected operation and realize active grid-connected support.

[0059] In a third aspect, the present invention provides an electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the method for active grid-connected operation of voltage source energy storage and new energy in coordination when executing the computer program.

[0060] In a fourth aspect, the present invention provides a computer-readable storage medium, wherein the computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the method for actively connecting the voltage source energy storage and new energy to the grid is implemented.

[0061] In a fifth aspect, the present invention provides a computer program product, which includes computer instructions, characterized in that the computer instructions instruct a computer to execute the method for active grid-connected operation of voltage source energy storage and new energy in coordination.

[0062] The beneficial effects of the present invention compared with the prior art are as follows:

[0063] The present invention proposes a method for active grid-connected operation of voltage source energy storage and new energy in coordination. The method calculates the static stability limit of the output power of different new energy power stations based on the Thevenin equivalent circuit of the voltage source energy storage power station / new energy hybrid power system. For new energy power stations with low static operation margin, the virtual impedance parameters and reactive output values ​​of their supporting voltage source energy storage power stations are changed to improve the stability limit of new energy grid-connected operation. Finally, the virtual impedance of the voltage source converter is adjusted according to the static operation margin of the new energy system. BRIEF DESCRIPTION OF THE DRAWINGS

[0064] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the embodiments of the present invention or the drawings of related technical solutions in the prior art are introduced below. It should be understood that the drawings introduced below are only for the convenience of clearly describing some embodiments of the technical solutions of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative work.

[0065] Figure 1 A flow chart of a method for active grid-connected operation of voltage source energy storage and new energy in coordination provided by the present invention;

[0066] Figure 2 It is the equivalent circuit of voltage source energy storage power station / new energy hybrid power system;

[0067] Figure 3 It is the AC side equivalent circuit of voltage source energy storage power station / new energy hybrid power system;

[0068] Figure 4 A voltage source type energy storage and new energy coordinated active grid-connected operation device provided by the present invention;

[0069] Figure 5 A schematic diagram of an electronic device provided by the present invention. DETAILED DESCRIPTION

[0070] The embodiments of the present invention are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and are not to be construed as limitations of the present invention. For the step numbers in the following embodiments, they are only provided for the convenience of explanation, and the order between the steps is not limited in any way, and the execution order of each step in the embodiment can be adaptively adjusted according to the understanding of those skilled in the art.

[0071] In the description of the present invention, unless otherwise clearly defined, terms such as setting, installing, connecting, etc. should be understood in a broad sense, and technicians in the relevant technical field can reasonably determine the specific meanings of the above terms in the present invention based on the specific content of the technical solution.

[0072] Terminology explanation:

[0073] High proportion of new energy power system: refers to a power system composed of a large number of new energy power generation equipment, such as wind turbines, solar photovoltaic generators, etc. As the proportion of new energy in primary energy consumption continues to increase, accelerating the replacement of fossil energy, the core feature of the new power system is that new energy occupies a dominant position. High proportion of new energy and extensive access: It is estimated that by 2060, the total installed capacity of wind power and photovoltaic power generation will reach about 60%, and the total power generation will reach about 35%.

[0074] The voltage source energy storage system is an innovative energy storage technology. Its core lies in the efficient storage and release of energy by precisely controlling the voltage level. The working principle of this system is based on the synergy of capacitors, inductors and switching components. The storage and extraction of electromagnetic field energy is achieved through the process of charging and discharging capacitors to inductors. Compared with traditional energy storage methods, voltage source energy storage has significant advantages, such as high charging rate, long cycle life, higher energy storage density and power density. These advantages make the voltage source energy storage system not only suitable for efficient energy storage of electric vehicles, ships, aircraft and other means of transportation, but also for energy balance and regulation of smart grids, as well as energy storage needs of small equipment such as power tools and household appliances. In addition, in the field of new energy power generation, the system will also play an important role in helping to achieve stable storage and efficient utilization of energy.

[0075] A high-proportion new energy grid refers to a power system composed of a large number of new energy power generation equipment (such as wind turbines, solar photovoltaic generators, etc.), in which the proportion of new energy power generation has increased significantly. With the continuous development and application of new energy technologies, the proportion of new energy in the power system has gradually increased, forming a high-proportion new energy grid. This kind of grid has the following characteristics: High proportion of new energy power generation: New energy power generation equipment has become an important part of the power grid, and its power generation accounts for a large proportion of the total power generation of the power grid. Difficulty in balancing power and electricity: Due to the randomness and volatility of new energy power generation, the difficulty of balancing power and electricity has increased, and a more flexible and intelligent scheduling method is needed. The challenges of safe and stable operation of the system are great: The access of new energy power generation equipment will affect the voltage, frequency, etc. of the power grid, making it more difficult to maintain the stability of the system. At the same time, the power adjustment range of new energy power generation equipment is small, which also has a great impact on the small disturbance stability of the system.

[0076] Virtual impedance refers to an impedance implemented on a digital signal processor (DSP) or similar device through software. It can be used to simulate components such as resistors, inductors, and capacitors in actual circuits to achieve specific functions. The principle of virtual impedance is to convert digital signals into analog signals through digital signal processing and apply virtual impedance to the analog signals. There are many ways to implement virtual impedance, the most common of which is through digital filters.

[0077] like Figure 1 As shown, the present invention provides a method for active grid-connected operation of voltage source energy storage and new energy in coordination, based on voltage source energy storage adaptive virtual impedance, comprising the following steps:

[0078] S100, obtaining the parameters of the new energy grid-connected node, and constructing the Thevenin equivalent circuit of the voltage source energy storage power station / new energy hybrid power system;

[0079] In the above step S100, the Thevenin equivalent circuit is constructed to obtain key parameters such as voltage, current, frequency and impedance of the new energy grid-connected node. These parameters are used to construct the Thevenin equivalent circuit of the voltage source energy storage power station / new energy hybrid power system. This circuit can simulate the electrical characteristics of the new energy grid-connected system under specific conditions, providing a basis for subsequent calculations and analysis.

[0080] S200. Calculate the static stability limit of the output power of different new energy power stations based on the Thevenin equivalent circuit of the voltage source energy storage power station / new energy hybrid power system;

[0081] In the above step S200, the static stability limit is calculated. Based on the constructed Thevenin equivalent circuit, the static stability limit of the output power of different renewable energy power stations can be calculated. This limit is the maximum output power that the renewable energy grid-connected system can withstand without external disturbance.

[0082] S300, based on the static stability limit, construct the relationship between the virtual impedance and reactive output of the energy storage system when the output of new energy is close to the static limit;

[0083] In the above step S300, a relationship model is constructed, and a relationship model between the virtual impedance and reactive output of the energy storage system when the output of new energy is close to the static limit is constructed according to the static stability limit. This model can reflect the dynamic relationship between the output of new energy, the virtual impedance of the energy storage system and the reactive output.

[0084] S400. Based on the relationship between the virtual impedance and reactive output of the energy storage system, for new energy power stations with low static operation margin, the virtual impedance parameters and reactive output values ​​of the supporting voltage source energy storage power stations are changed to improve the stability limit of new energy grid-connected operation, including:

[0085] When a new energy source fails and its output approaches the static limit, the virtual impedance and reactive output of the energy storage system are increased to actively support the grid;

[0086] When the fault of the new energy source is eliminated, the virtual impedance of the energy storage system is reduced when the output static limit margin is large.

[0087] In the above step S400, the virtual impedance and reactive output are adaptively adjusted. When a new energy fails and the output approaches the static limit, in order to maintain the stability of the system, it is necessary to increase the virtual impedance and reactive output of the energy storage system to actively support the power grid. The increase in virtual impedance can reduce the short-circuit current of the system and reduce the impact of the fault on the system; the increase in reactive output can enhance the voltage support capacity of the system and improve the stability of the system. When the new energy fault is eliminated, if the system's output static limit margin is large, that is, the system still has a large safety margin from the static limit, then the virtual impedance of the energy storage system can be appropriately reduced to reduce the operating cost of the system and improve the economy. At the same time, the charging and discharging strategy of the energy storage system can also be optimized to further improve the efficiency of the system.

[0088] The voltage source type energy storage and new energy coordinated active grid-connected operation method based on voltage source type energy storage adaptive virtual impedance provided by the present invention obtains the parameters of the new energy grid-connected node, constructs the Thevenin equivalent circuit, calculates the static stability limit, and constructs the relationship between the virtual impedance, reactive output and new energy output of the energy storage system accordingly. When the new energy output approaches the static limit, the virtual impedance parameters and reactive output value of the energy storage system are changed to improve the stability limit of the new energy grid-connected operation.

[0089] This method can effectively improve the stability of the new energy grid-connected system by adaptively adjusting the virtual impedance and reactive output of the energy storage system. According to the Thevenin equivalent circuit of the voltage source energy storage power station / new energy hybrid power system, the static stability limit of the output power of different new energy power stations is calculated. For new energy power stations with low static operating margins due to faults, the virtual impedance parameters and reactive output values ​​of their supporting voltage source energy storage power stations are changed to improve the stability limit of new energy grid-connected operation and actively support the power grid.

[0090] Specifically, this adjustment method can cope with various faults and abnormal situations, ensuring that the system remains stable in a complex and changeable operating environment. The method can flexibly adjust the control strategy of the energy storage system according to different fault types and severity. This enables the new energy grid-connected system to better adapt to various operating conditions and improve the flexibility and reliability of the system. After the fault is eliminated, the operating cost of the system can be reduced by reducing the virtual impedance of the energy storage system. At the same time, the method can also optimize the charging and discharging strategy of the energy storage system and further improve the economy of the system. The method of actively supporting the operation of the power grid at the time of fault of a high proportion of new energy power grid based on voltage source energy storage adaptive virtual impedance has significant principles and advantages. It can not only improve the stability and adaptability of the system, but also optimize the economy of the system and promote the widespread application of new energy.

[0091] The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments. The control method will be described in detail below in conjunction with specific implementation steps:

[0092] Step 1: Measure the voltage, frequency, and impedance of the new energy grid-connected node and construct a multi-port Thevenin equivalent circuit; Figure 2 As shown, it is the equivalent circuit of voltage source energy storage power station / new energy hybrid power system.

[0093] Assume that the current injected into the AC system by each renewable energy grid-connected bus is Then the voltage of each grid-connected bus node It can be expressed as

[0094]

[0095] In the formula is the AC grid equivalent impedance matrix Z at the new energy grid-connected busbar eq The i-th row and j-th column element of .

[0096] The MRSCR (renewable energy multi-station short-circuit ratio) at the i-th renewable energy grid-connected bus in the system is:

[0097]

[0098] Where: is the nominal voltage of the i-th grid-connected bus node; is the voltage generated by the power generation of the equipment (new energy) at the i-th node, and the subscript RE represents the new energy power generation equipment / station; The short-circuit current provided by the i-th renewable energy power generation equipment / station. Let the actual operating voltage of the i-th grid-connected bus node be

[0099] After node 1 is connected to the energy storage, it is equivalent to connecting the ground branch z0 in parallel at node 1.

[0100] After the energy storage is connected to node 1, the equivalent impedance matrix Z eq becomes the equivalent node impedance matrix Z e ' q , whose expression is

[0101]

[0102] Where: is the transpose of Z1, Z1 is the equivalent impedance matrix Z eq The first row vector of , z0 is the equivalent impedance of the grid-type energy storage.

[0103] Z eq After expansion, the formula for any element is as follows:

[0104]

[0105] In the formula, is the AC grid equivalent impedance matrix Z at the new energy grid-connected busbar eq is the i-th row and j-th column element of ; z0 is the equivalent impedance of the grid-type energy storage.

[0106] After node 1 is connected to energy storage, the equivalent impedance matrix Z eq All elements in will decrease, and the self-impedance Z of node 1 eq11 The impedance provided by the grid-type storage can enhance the short-circuit ratio of the new energy system.

[0107] Step 2: Calculate the static limit current and static limit power angle of the new energy grid-connected node, refer to Figure 3 , which is the AC side equivalent circuit of the voltage source energy storage power station / new energy hybrid power system.

[0108] The grid-connected converter output voltage vector is U t ∠0;X g is the equivalent inductance L between the grid-connected converter and the grid g The fundamental wave equivalent impedance of the grid voltage vector is U g ∠-δ t .

[0109] The voltage amplitude U of the grid-connected node of the new energy grid-connected converter t The expression is:

[0110]

[0111] Active power exchanged between the new energy grid-connected converter and the infinite power grid:

[0112]

[0113] At the same time, the d-axis current I can also be obtained d With phase angle δ t The relationship between:

[0114] I d X g =U g sinδ t

[0115] Substituting into the above, we can get P out With δ t The relationship between .

[0116]

[0117] Under weak grid conditions, the output active power of the renewable energy grid-connected converter with current source characteristics on the AC side is limited, and its maximum value (at I q = 0), as the grid base frequency impedance X g As the value of increases, the maximum transmittable active power decreases.

[0118]

[0119] Whether it is P out -I d The curve is still P out -δ t The curve has an extreme point, the static limiting current I d_cr , when I q = 0, we can find

[0120]

[0121] Therefore, when I q =0 when the static limiting current I d_cr With SCR, rated current I d_rated The relationship is

[0122]

[0123] Where U g is the grid voltage vector amplitude; X gis the equivalent inductance L between the grid-connected converter and the grid g The fundamental wave equivalent impedance; SCR is the short circuit ratio; I d_rated is the rated current.

[0124] When the new energy grid-connected converter outputs rated current, its static stability margin becomes smaller and smaller as the SCR decreases.

[0125] Step 3: When the output of new energy approaches the static limit, increase the virtual impedance and reactive output of the energy storage system.

[0126] The voltage generated by the virtual impedance is added as feedback to the output of the droop link to generate a new reference voltage. The virtual impedance is expressed as follows:

[0127]

[0128] Among them, R v is the virtual resistance component, L v is the virtual inductance component.

[0129] After adding the virtual impedance control loop, the output voltage expression of the inverter is:

[0130] U0(s)=G(s)U ref -(G(s)Z v (s)+Z0(s))I0(s)

[0131] G(s) is the voltage closed-loop transfer function of the inverter, and Z0(s) is the inverter output impedance.

[0132]

[0133] The equivalent output impedance is composed of the inverter output impedance and the virtual impedance, and the expression is:

[0134]

[0135] Therefore, increasing the virtual impedance parameters of the energy storage system can increase the output impedance of the energy storage system; when the short-circuit ratio decreases due to a fault in the power grid, the system short-circuit ratio can be increased, the grid-connected stability limit of the new energy system can be improved, and the power grid can be actively supported.

[0136] Step 4: When the static limit margin of the new energy output is large, the virtual impedance of the energy storage system is reduced;

[0137] Virtual impedance simulates the effect of actual line impedance, and its impact on the stability of the energy storage system is the same as that of the transmission line impedance. As the virtual impedance value increases, the inverter output voltage decreases rapidly, which is not conducive to the normal operation of electrical equipment in the power grid. When the fault is eliminated and the static stability margin of the new energy power generation system is large, reducing the virtual impedance parameter value is conducive to system operation.

[0138] The virtual impedance of the voltage source converter is adjusted according to the static operation margin of the new energy system. The present invention proposes a method for actively supporting the operation of a high-proportion new energy power grid at the time of fault based on the adaptive virtual impedance of the voltage source energy storage. According to the Thevenin equivalent circuit of the voltage source energy storage power station / new energy hybrid power system, the static stability limit of the output power of different new energy power stations is calculated. For new energy power stations with low static operation margins, the virtual impedance parameters and reactive output values ​​of their supporting voltage source energy storage power stations are changed to improve the stability limit of new energy grid-connected operation.

[0139] like Figure 4 As shown, the second object of the present invention is to provide a system for actively supporting operation of a high-proportion new energy power grid at fault time, comprising:

[0140] An acquisition module 100 is used to acquire parameters of new energy grid-connected nodes and construct a Thevenin equivalent circuit of a voltage source energy storage power station / new energy hybrid power system;

[0141] A calculation module 200 is used to calculate the static stability limit of the output power of different new energy power stations according to the Thevenin equivalent circuit of the voltage source energy storage power station / new energy hybrid power system;

[0142] A construction module 300 is used to construct the relationship between the virtual impedance and reactive output of the energy storage system when the output of the new energy is close to the static limit based on the static stability limit;

[0143] The improving module 400 is used to change the virtual impedance parameters and reactive output values ​​of the supporting voltage source energy storage power station based on the relationship between the virtual impedance and reactive output of the energy storage system, for the new energy power station with low static operation margin, so as to improve the stability limit of the new energy grid-connected operation.

[0144] The system is based on the above-mentioned voltage source energy storage and new energy coordinated active grid-connected operation method.

[0145] The present invention effectively improves the short-circuit capacity and power receiving capacity of the system in the new power system. When disturbance or failure occurs, it actively builds system stability, improves the power grid's absorption level of renewable energy power generation, improves the power grid's regulation capability, promotes the absorption of new energy and distributed power sources, and improves the vulnerability of the new power system due to the access of a high proportion of renewable energy and a high proportion of power electronic equipment.

[0146] like Figure 5 As shown, the third purpose of the embodiment of the present invention is to provide an electronic device, including a memory 701, a processor 702, and a computer program stored in the memory 701 and executable on the processor, wherein the processor implements the method for actively supporting the operation of a power grid at the time of a high proportion of new energy power grid failure when executing the computer program. It also includes a communication interface 703 and a bus 704.

[0147] The fourth objective of an embodiment of the present invention is to provide a computer-readable storage medium, wherein the computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the method for actively connecting the voltage source energy storage to the grid in coordination with new energy is implemented.

[0148] The fifth objective of an embodiment of the present invention is to provide a computer program product, which includes computer instructions, characterized in that the computer instructions instruct a computer to execute the method for active grid-connected operation of voltage source energy storage and new energy in coordination.

[0149] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0150] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0151] The present invention may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Moreover, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, readable storage media, optical storage, etc.) containing computer-usable program codes.

[0152] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0153] Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0154] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the relevant field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents. Any modification or equivalent replacement that does not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A method for active grid-connected operation of voltage source energy storage and new energy, characterized in that: include: Obtain the parameters of the new energy grid-connected nodes and construct the Thevenin equivalent circuit of the voltage source energy storage power station / new energy hybrid power system; According to the Thevenin equivalent circuit of the voltage source energy storage power station / new energy hybrid power system, the static stability limit of the output power of different new energy power stations is calculated; Based on the static stability limit, the relationship between the virtual impedance and reactive output of the energy storage system is constructed when the output of new energy approaches the static limit; Based on the relationship between the virtual impedance and reactive output of the energy storage system, for new energy power stations with low static operation margin, the virtual impedance parameters and reactive output values ​​of their supporting voltage source energy storage power stations are changed to improve the stability limit of new energy grid-connected operation and achieve active grid-connected support.

2. The method for active grid-connected operation of voltage source energy storage and new energy in coordination according to claim 1 is characterized in that: The obtaining of new energy grid-connected node parameters and the construction of the Thevenin equivalent circuit of a voltage source energy storage power station / new energy hybrid power system include: Obtain new energy grid-connected node parameters, including: voltage, current, frequency, and impedance; Assume that the current injected into the AC system by each renewable energy grid-connected bus is Then the voltage of each grid-connected bus node Expressed as In the formula, is the AC grid equivalent impedance matrix Z at the new energy grid-connected busbar eq The i-th row and j-th column element of The short-circuit ratio MRSCR of the new energy multi-station at the i-th new energy grid-connected busbar is: Where: is the nominal voltage of the i-th grid-connected bus node; is the voltage generated by the power generated by the new energy equipment at the i-th node, and the subscript RE represents the new energy power generation equipment / station; is the short-circuit current provided by the i-th renewable energy power generation equipment / station; let the actual operating voltage of the i-th grid-connected bus node be Based on the equivalent circuit of voltage source energy storage power station / new energy hybrid power system, a multi-port Thevenin equivalent circuit is constructed: After node 1 is connected to the energy storage, it is equivalent to connecting the ground branch z0 in parallel at node 1; after the energy storage is connected to node 1, the equivalent impedance matrix Z eq becomes the equivalent node impedance matrix Z e ' q , whose expression is Where: is the transpose of Z1, Z1 is the equivalent impedance matrix Z eq The first row vector of , z0 is the equivalent impedance of the grid-type energy storage; Z eq After expansion, the formula for any element is as follows: In the formula, is the AC grid equivalent impedance matrix Z at the new energy grid-connected busbar eq is the i-th row and j-th column element of ; z0 is the equivalent impedance of the grid-type energy storage.

3. The method for active grid-connected operation of voltage source energy storage and new energy in coordination according to claim 1 is characterized in that: The calculation of the static stability limits of the output power of different new energy power stations includes calculating the static limit current and the static limit power angle of the new energy grid-connected node.

4. The method for active grid-connected operation of voltage source energy storage and new energy in coordination according to claim 1 is characterized in that: The method of calculating the static stability limit of the output power of different new energy power stations according to the Thevenin equivalent circuit of the voltage source energy storage power station / new energy hybrid power system includes: The grid-connected converter output voltage vector is U t ∠0;X g is the equivalent inductance L between the grid-connected converter and the grid g The fundamental wave equivalent impedance of the grid voltage vector is U g ∠-δ t , then the voltage amplitude of the grid-connected node of the new energy grid-connected converter is U t The expression is: Active power exchanged between the new energy grid-connected converter and the infinite power grid: Calculate the d-axis current I d With phase angle δ t The relationship between: I d X g =U g sinδ t Get P out With δ t The relationship between: On the AC side under weak grid conditions, the grid base frequency impedance X g , the corresponding maximum transmittable active power is When I q = 0, find When I q =0 when the static limiting current I d_cr With SCR, rated current I d_rated The relationship is Where U g is the grid voltage vector amplitude; X g is the equivalent inductance L between the grid-connected converter and the grid g The fundamental wave equivalent impedance; SCR is the short circuit ratio; I d_rated is the rated current.

5. The method for active grid-connected operation of voltage source energy storage and new energy in coordination according to claim 1 is characterized in that: The relationship between the virtual impedance and reactive output of the energy storage system when the output of new energy is close to the static limit is constructed, including: The voltage generated by the virtual impedance is added as feedback to the output of the droop link to generate a new reference voltage. The virtual impedance is expressed as: Among them, R v is the virtual resistance component, L v is the virtual inductance component; After adding the virtual impedance control loop, the output voltage expression of the inverter is: U0(s)=G(s)U ref -(G(s)Z v (s)+Z0(s))I0(s) G(s) is the voltage closed-loop transfer function of the inverter, and Z0(s) is the inverter output impedance.

6. The method for active grid-connected operation of voltage source energy storage and new energy in coordination according to claim 1 is characterized in that: For the new energy power station with low static operation margin, the virtual impedance parameters and reactive output value of the supporting voltage source energy storage power station are changed to improve the stability limit of the new energy grid-connected operation, including: When a new energy source fails and its output approaches the static limit, the energy storage system’s virtual resistance and reactive output are increased to actively support the grid; When the fault of the new energy source is eliminated, the virtual impedance of the energy storage system is reduced when the output static limit margin is large.

7. The method for active grid-connected operation of voltage source energy storage and new energy in coordination according to claim 1 is characterized in that: Increasing the virtual impedance and reactive output of the energy storage system refers to increasing the system short-circuit ratio when the short-circuit ratio decreases due to a fault in the power grid, and actively supporting the power grid.

8. A voltage source energy storage and new energy coordinated active grid-connected operation system, characterized in that: include: The acquisition module is used to obtain the parameters of the new energy grid-connected nodes and construct the Thevenin equivalent circuit of the voltage source energy storage power station / new energy hybrid power system; A calculation module, used to calculate the static stability limit of the output power of different renewable energy power stations based on the Thevenin equivalent circuit of the voltage source energy storage power station / new energy hybrid power system; A construction module is used to construct the relationship between the virtual impedance and reactive output of the energy storage system when the output of new energy is close to the static limit based on the static stability limit; The improvement module is used to change the virtual impedance parameters and reactive output values ​​of the supporting voltage source energy storage power station based on the relationship between the virtual impedance and reactive output of the energy storage system, for new energy power stations with low static operation margin, so as to improve the stability limit of new energy grid-connected operation.

9. An electronic device, characterized in that: It includes a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, it implements the method for active grid-connected operation of voltage source type energy storage and new energy in coordination as described in any one of claims 1 to 7.

10. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the method for coordinated active grid-connected operation of voltage source energy storage and new energy as described in any one of claims 1 to 7 is implemented.

11. A computer program product, comprising computer instructions, characterized in that: The computer instructions instruct the computer to execute the method for coordinated active grid-connected operation of voltage source energy storage and new energy as described in any one of claims 1-7.

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