Distributed power supply-oriented intelligent power distribution cabinet bidirectional power quality control system

Abstract

The invention relates to an intelligent power distribution cabinet bidirectional power quality control system for distributed power supply and a control method thereof. The control system comprises a plurality of micro-grid units, each micro-grid unit is provided with a power distribution cabinet, and the plurality of power distribution cabinets are connected to a common direct current bus and are used for converting alternating current and direct current electric energy of respective micro-grids and executing frequency modulation control based on electric energy quality requirements. Each power distribution cabinet is provided with a frequency adjusting unit which is used for collecting local power transmission frequency and calculating a frequency standard index. And the system determines an adjustment sequence according to the frequency standard indexes of the plurality of micro-grid units and preset adjustment weight values thereof, preferentially takes the frequency standard index of a high-weight node as an adjustment reference, and adjusts the active power output of the rest micro-grids step by step in a sequential transmission mode.

Description

Technical Field

[0001] The present invention belongs to the technical field of electric energy control, and in particular relates to a bidirectional power quality control system for an intelligent power distribution cabinet for distributed power supply. Background Art

[0002] In distributed power supply systems, microgrids, as regional, independent energy supply units, offer self-generation, self-balancing, and self-control. They have been widely used in off-grid power systems powered by renewable energy, such as parks, communities, data centers, and remote areas. Multiple microgrid units are connected to a common DC bus via power distribution equipment to form a multi-node parallel structure, which helps improve the system's power supply flexibility and the proportion of renewable energy access. However, due to the diverse needs of each microgrid, their power quality requirements vary significantly. In particular, frequency stability is crucial, as different load levels have varying tolerances for frequency regulation accuracy. Traditional microgrid control methods often target a uniform frequency, ignoring inter-node variations. This can easily lead to instability in critical load areas due to frequency disturbances. Furthermore, current control methods are mostly static responses, lacking a dynamic, quantitative description of the system's internal frequency state, making it difficult to achieve hierarchical, orderly regulation across multiple nodes. Therefore, a standardized metric is urgently needed to characterize the frequency state of a microgrid. This metric, combined with the load level and weight of each node, can be used to implement a coordinated frequency control strategy within the system, enhancing the dynamic adaptability and power quality assurance capabilities of multi-microgrid systems.

[0003] According to the relevant public technologies, the technical solution with the publication number CN116780639B proposes a distributed photovoltaic grid-connected control method, which determines the subsequent processing strategy for the photovoltaic components by obtaining the transient electrical parameter value when the switch in the distribution network trips. The technical solution with the publication number EP3079027A4 proposes a monitoring system for a distributed power generation air-conditioning system, which calculates the working status of each link in the air-conditioning system by arranging multiple monitoring elements in the air-conditioning duct to control the power transmission strategy of the power generation component. The technical solution with the publication number US20170012428A1 proposes a system for effective operation control between distributed power sources, which provides a virtual current in the same direction as the forward power flow by setting a virtual current output unit.

[0004] The above technical solutions all propose various control methods or control systems for distributed power supply systems, aiming to improve the power supply quality or power utilization efficiency of distributed systems. However, for the actual power consumption scenarios with focused requirements in microgrids, relevant control methods are still needed.

[0005] The foregoing discussion of the background art is intended only to facilitate an understanding of the present invention. This discussion does not acknowledge or admit that any of the material referred to is part of the common general knowledge. Summary of the Invention

[0006] The object of the present invention is to provide a bidirectional power quality control system for an intelligent distribution cabinet for distributed power supply and a control method thereof. The control system includes a plurality of microgrid units, each of which is provided with a distribution cabinet. The plurality of distribution cabinets are connected to a common DC bus for converting the AC and DC power of their respective microgrids and performing frequency modulation control based on power quality requirements. Each distribution cabinet is provided with a frequency adjustment unit for collecting the local transmission frequency and calculating the frequency standard index. The system determines the adjustment order based on the frequency standard indexes of the plurality of microgrid units and their preset adjustment weight values, prioritizes the frequency standard index of the high-weight node as the adjustment benchmark, and adjusts the active output of the remaining microgrids step by step in a sequential transmission manner.

[0007] The present invention adopts the following technical solutions: a bidirectional power quality control system for an intelligent power distribution cabinet for distributed power supply, wherein the control system is used to control the operation of multiple microgrid units in a power supply network system;

[0008] Each microgrid unit includes one or more power generation sources and energy storage devices, and at least one power distribution cabinet; multiple microgrid units are connected to a common DC bus through the configured power distribution cabinet; the power distribution cabinet is used to convert the power input or output of the connected microgrid units operating in AC form into AC / DC, and perform frequency regulation control based on the power quality level of the microgrid units;

[0009] Each of the power distribution cabinets is equipped with a frequency adjustment unit, and the frequency adjustment unit is configured as follows:

[0010] Obtain the real-time transmission frequency of the local microgrid unit;

[0011] Calculating a frequency standard index using the real-time power transmission frequency;

[0012] Obtain frequency standard index of each microgrid unit in the power supply network system;

[0013] Based on the local frequency standard index and the frequency standard index of each microgrid unit in the power supply network system, the power generation or load power of the local microgrid unit is adjusted.

[0014] Preferably, the frequency adjustment unit is configured to calculate a frequency standard index using the real-time power transmission frequency, using the following calculation method:

[0015]

[0016] Among them, f st is the frequency standard index, f is the real-time transmission frequency, f min and f maxThe lower and upper limits of the transmission frequency set for the user area of the microgrid unit; f U and f L are the upper and lower saturation values, respectively;

[0017] Through the above calculation method, the real-time frequency is standardized to a control index between [-1, 1].

[0018] Preferably, in the control system, an adjustment weight value is set for each microgrid unit; based on the adjustment weight value of the microgrid unit, the frequency standard index of at least one microgrid unit is selected as the adjustment benchmark for power quality; and the distribution cabinets of the remaining microgrid units adjust the internal power quality of the microgrid units to which they belong based on the adjustment benchmark.

[0019] Furthermore, a bidirectional power quality control method for an intelligent distribution cabinet for distributed power supply is proposed. The control method is applied to the bidirectional power quality control system for an intelligent distribution cabinet for distributed power supply; the control method comprises the following steps:

[0020] S100: Standardize the transmission frequency in the microgrid unit and convert the transmission frequency into a frequency standard index f st ;

[0021] S200: Select a frequency standard index f of a microgrid unit st As the adjustment basis, the frequency standard index f st Assign to the distribution cabinet of one or more other microgrid units;

[0022] S300: The power distribution cabinet of each microgrid unit adjusts the active power P of the microgrid unit by controlling the d-axis current based on the local frequency standard index. e Output.

[0023] Preferably, the control method further comprises executing two processing stages; wherein,

[0024] In the first processing stage, a frequency standard index of a microgrid unit is selected as a regulation benchmark, and the regulation benchmark is sent to the distribution cabinets of the remaining microgrid units. Each distribution cabinet performs power quality regulation for the corresponding microgrid unit based on the same regulation benchmark;

[0025] In the second processing stage, following the first processing stage, the adjustment weight values of each microgrid unit are sorted in descending order, and the frequency standard index f of the i-th microgrid unit is st(i) Send it to the i+1th microgrid unit; thereafter, the i+1th microgrid unit combines and analyzes the local frequency standard index f st(i+1) With f st(i), thereby regulating the power quality of the local microgrid unit.

[0026] Preferably, in the first processing stage, a frequency standard index of a microgrid unit is selected as a regulation benchmark based on one of the following conditions:

[0027] When there is only one microgrid unit, the frequency standard index f st When ≠0, this microgrid unit is selected;

[0028] When there are two or more microgrid units, the frequency standard index f st When ≠0, the microgrid unit with the highest adjustment weight value is selected.

[0029] The beneficial effects achieved by the present invention are:

[0030] 1. This technical solution introduces a frequency standard index as a unified, dimensionless control indicator that accurately reflects the real-time frequency status of each microgrid unit and enables differentiated frequency regulation based on the power quality level of each microgrid. Compared to traditional unified frequency control methods, this approach more effectively ensures frequency stability in highly sensitive load areas, improving system reliability and service capabilities.

[0031] 2. The control system of this technical solution establishes a control priority chain by setting the regulation weights of microgrid units, achieving an orderly power regulation process from the master node to the slave nodes. This sequential transmission method prevents the disorderly spread of frequency anomalies within the system, optimizes the allocation of regulation resources, and effectively improves the coordination efficiency and dynamic response performance of the entire distributed power supply system.

[0032] 3. The frequency standard index calculation method proposed in this technical solution is applicable to any set frequency range. The distribution cabinet control logic module can be embedded in existing microgrid systems and operate independently. It features independent structure, low communication requirements, and modular algorithms. This system can be flexibly deployed in various microgrid scenarios, adapting to different load levels and regulation strategies, and has promising engineering application prospects.

[0033] 4. The software and hardware parts of the control system of this technical solution adopt a modular design. The various working modules and components of the hardware part of the system, as well as the instructions, parameters, and algorithms of the software part can be easily replaced and / or upgraded at a later stage, thereby reducing the construction cost and maintenance cost of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] The present invention can be further understood from the following description in conjunction with the accompanying drawings. The components in the figures are not necessarily drawn to scale, but rather the emphasis is placed on illustrating the principles of the embodiments. In different views, the same reference numerals designate corresponding parts.

[0035] Description of the accompanying drawings: 110 - microgrid unit; 120 - power distribution cabinet; 130 - DC bus; 131 - sub-model; 140 - communication line; 122 - microgrid unit with weight i; 124 - microgrid unit 1 with weight i+1;

[0036] Figure 1 This is a schematic diagram of the architecture of the control system of the present invention;

[0037] Figure 2 is a step diagram of the control method described in an embodiment of the present invention;

[0038] Figure 3 Schematic diagram of the process of adjusting two microgrid units based on the frequency standard index value in an embodiment of the present invention;

[0039] Figure 4 Schematic diagram of frequency and power output curves during the regulation of two microgrid units in an embodiment of the present invention. DETAILED DESCRIPTION

[0040] In order to make the purpose, technical solutions and advantages of the present invention clearer, the present invention is further described in detail below in conjunction with its embodiments; it should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention. For those skilled in the art, other systems, methods and / or features of the present embodiment will become apparent after reviewing the following detailed description. It is intended that all such additional systems, methods, features and advantages are included in this specification. Included within the scope of the present invention and protected by the appended claims. Additional features of the disclosed embodiments are described in the following detailed description, and these features will be apparent from the following detailed description.

[0041] The same or similar reference numerals in the drawings of the embodiments of the present invention correspond to the same or similar components. In the description of the present invention, it should be understood that if there are terms such as "upper", "lower", "left", "right", etc. indicating an orientation or positional relationship, they are based on the orientation or positional relationship shown in the drawings. This is only for the convenience of describing the present invention and simplifying the description, and does not indicate or imply that the device or component referred to must have a specific orientation. The terms used in the drawings to describe the positional relationship are only for illustrative purposes and cannot be understood as limiting this patent. For those skilled in the art, the specific meanings of the above terms can be understood according to the specific circumstances.

[0042] Example 1: For example, a bidirectional power quality control system for an intelligent power distribution cabinet for distributed power supply is proposed, wherein the control system is used to control the operation of multiple microgrid units in a power supply network system;

[0043] Each microgrid unit includes one or more power generation sources and energy storage devices, and at least one power distribution cabinet; multiple microgrid units are connected to a common DC bus through the configured power distribution cabinet; the power distribution cabinet is used to convert the power input or output of the connected microgrid units operating in AC form into AC / DC, and perform frequency regulation control based on the power quality level of the microgrid units;

[0044] Each of the power distribution cabinets is equipped with a frequency adjustment unit, and the frequency adjustment unit is configured as follows:

[0045] Obtain the real-time transmission frequency of the local microgrid unit;

[0046] Calculating a frequency standard index using the real-time power transmission frequency;

[0047] Obtain frequency standard index of each microgrid unit in the power supply network system;

[0048] Based on the local frequency standard index and the frequency standard index of each microgrid unit in the power supply network system, the power generation or load power of the local microgrid unit is adjusted.

[0049] Preferably, the frequency adjustment unit is configured to calculate a frequency standard index using the real-time power transmission frequency, using the following calculation method:

[0050]

[0051] Among them, f st is the frequency standard index, f is the real-time transmission frequency, f min and f max The lower and upper limits of the transmission frequency set for the user area of the microgrid unit; f U and f L are the upper and lower saturation values, respectively;

[0052] Through the above calculation method, the real-time frequency is standardized to a control index between [-1, 1].

[0053] Preferably, in the control system, an adjustment weight value is set for each microgrid unit; based on the adjustment weight value of the microgrid unit, the frequency standard index of at least one microgrid unit is selected as the adjustment benchmark for power quality; and the distribution cabinets of the remaining microgrid units adjust the internal power quality of the microgrid units to which they belong based on the adjustment benchmark.

[0054] Furthermore, a bidirectional power quality control method for an intelligent distribution cabinet for distributed power supply is proposed. The control method is applied to the bidirectional power quality control system for an intelligent distribution cabinet for distributed power supply; the control method comprises the following steps:

[0055] S100: Standardize the transmission frequency in the microgrid unit and convert the transmission frequency into a frequency standard index f st ;

[0056] S200: Select a frequency standard index f of a microgrid unit st As the adjustment basis, the frequency standard index f st Assign to the distribution cabinet of one or more other microgrid units;

[0057] S300: The power distribution cabinet of each microgrid unit adjusts the active power P of the microgrid unit by controlling the d-axis current based on the current frequency standard index. e Output.

[0058] Preferably, the control method may also be performed in two processing stages; wherein,

[0059] In the first processing stage, a frequency standard index of a microgrid unit is selected as a regulation benchmark, and the regulation benchmark is sent to the distribution cabinets of the remaining microgrid units. Each distribution cabinet performs power quality regulation for the corresponding microgrid unit based on the same regulation benchmark;

[0060] In the second processing stage, following the first processing stage, the adjustment weight values of each microgrid unit are sorted in descending order, and the frequency standard index f of the i-th microgrid unit is st(i) Send it to the i+1th microgrid unit; thereafter, the i+1th microgrid unit combines and analyzes the local frequency standard index f st(i+1) With f st(i) , thereby regulating the power quality of the local microgrid unit.

[0061] Preferably, in the first processing stage, a frequency standard index of a microgrid unit is selected as a regulation benchmark based on one of the following conditions:

[0062] When there is only one microgrid unit, the frequency standard index f st When ≠0, this microgrid unit is selected;

[0063] When there are two or more microgrid units, the frequency standard index f st When ≠0, the microgrid unit with the highest adjustment weight value is selected.

[0064] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. It should be understood that the specific structures and components involved are only used to better illustrate the technical concept of the present invention, and those skilled in the art may adjust or replace the specific forms without departing from the spirit of the present invention.

[0065] The control system proposed in this technical solution is suitable for distributed power supply systems in remote living communities. Specifically, it includes proposing a control method based on an intelligent distribution cabinet. This control method dynamically adjusts the output frequency or voltage parameters of each microgrid unit according to the power quality requirements within the substation of each microgrid unit, so as to achieve output quality optimization for the main power grid and input quality assurance for the terminal load. The system judges the power supply and demand status of each microgrid, adjusts the power control module in the intelligent distribution cabinet connected to each microgrid interface, dynamically adjusts the effective output power, and coordinates the operating status of multiple microgrids through a frequency / voltage standardization mechanism, thereby achieving stable two-way power quality control under a multi-microgrid interconnected structure. The following will describe in detail the composition of the multi-frequency control system of multiple independent microgrids in the embodiment of the present invention in conjunction with the accompanying drawings.

[0066] As attached Figure 1 , illustrating an exemplary embodiment of the control system. In this exemplary embodiment, the distributed power supply network system includes three microgrid units 110 (labeled 110a, 110b, and 110c for ease of presentation) and three power distribution cabinets 120 (labeled 120a, 120b, and 120c for ease of presentation) connected to each corresponding microgrid unit. However, this technical solution does not limit the number of microgrid units; the number of microgrid units is set as an example for ease of presentation only.

[0067] Preferably, each microgrid unit 110 is connected to a corresponding power distribution cabinet 120. Each power distribution cabinet 120 is respectively provided at the interface of the corresponding microgrid to facilitate independent regulation and coordinated control of the power input / output of the microgrid unit 110.

[0068] Exemplarily, each microgrid unit 110 is an independently deployed local power supply unit, which can generally include one or more distributed power supply modules such as photovoltaic arrays, wind turbines and other power generation equipment, as well as corresponding energy storage equipment, to provide self-generation and peak-shaving capabilities for basic life loads.

[0069] Exemplarily, each microgrid unit 110 may further include conventional energy storage units, emergency backup energy storage devices, static transfer switches, conventional circuit breakers, automatic load switches, and other equipment to meet actual power supply needs. Furthermore, exemplary distributed power generation equipment installed in microgrid units 110 may include wind power generation equipment, photovoltaic power generation equipment, hydropower generation equipment, and other new energy generation technology equipment; and may also include traditional energy generation equipment such as small diesel generators.

[0070] Each distribution cabinet 120 is arranged at the power transmission interface of the corresponding microgrid unit to handle the two-way transmission and conversion of electric energy between the DC bus 130 and the microgrid unit 110. The distribution cabinet 120 includes converting the AC power generated inside the microgrid unit (such as the AC power generated by wind power generation) into DC power and outputting it to the DC grid-connected line; on the other hand, it can also convert the received DC power into AC power and supply it back to the electrical appliances inside the microgrid unit. In addition, the distribution cabinet 120 also has a frequency coordination control function, which can dynamically adjust the power load range based on the frequency operation conditions of the substation it serves.

[0071] Preferably, each intelligent power distribution cabinet is internally equipped with a frequency adjustment unit (not shown in the figure). The frequency adjustment unit exchanges information with the power distribution cabinets of adjacent microgrid units via the communication line 140. Each power distribution cabinet 120 is configured to obtain the current operating frequency information of other microgrid units and dynamically standardize the allowed frequency range set by the local microgrid unit to enhance the coordinated control capability of the entire power supply network system.

[0072] In a microgrid power supply system, the frequency of the output power of a microgrid unit or the absorbed power on the load side is affected by power balance. If the power generation exceeds the load demand, the transmission frequency fluctuates positively, meaning the frequency value increases. If the power generation is less than the load demand, the transmission frequency fluctuates negatively, meaning the frequency value decreases. When the power generation matches the load demand, the frequency stabilizes at a set value, such as 50Hz.

[0073] In the microgrid unit in island mode, the inverter configured in the power distribution cabinet 120 can dynamically adjust the power output of the power generation equipment according to the real-time measured transmission frequency error. That is:

[0074] P out =P0+K p (f ref -f), formula 1;

[0075] In formula 1, P out is the active power output value of the microgrid unit controlled by the current distribution cabinet; P0 is the system's reference power output at the reference frequency (commonly 50Hz or 60Hz), which is the default output when the frequency has no deviation; f is the actual operating frequency of the current microgrid, f ref That is, the reference frequency; K P () is the regulation strategy function of the distribution cabinet, which can be programmed by relevant technical personnel based on f refThe deviation value from the actual operating frequency f is used to regulate the active power output value. In addition, for different microgrid units, the power equipment and power quality requirements of their power supply areas are different. For example, for daily electricity demand, the power demand is not high, allowing for larger power quality fluctuations and slower power quality regulation response; while for application scenarios such as data centers and medical facilities, higher power quality and faster power quality regulation response are required. Therefore, in a preferred embodiment, the regulation strategy function K of the equipment in each distribution cabinet is P () can also be designed specifically to adapt to different microgrid area requirements, such as the regulation strategy function K P () can be a function based on proportional or integral control algorithm to ensure smooth dynamic response of the system.

[0076] Preferably, in an exemplary embodiment, the present technical solution can implement differentiated frequency adaptive regulation control for multiple microgrid units. During the regulation process, the power supply network system sets different allowable operating frequency ranges for each microgrid through the distribution cabinet, and uses the range as the basis for the microgrid to participate in the system frequency coordination. Specifically, based on the specific power consumption within the microgrid unit, different power quality requirements are imposed on the unit substation. For example, for example, microgrid unit 110a can be set to a wider frequency tolerance of 59.4 to 60.6 Hz, microgrid unit 110b can be set to a medium regulation range of 59.7 to 60.3 Hz, and microgrid unit 110c can be set to a fine regulation range of 59.5 to 60.5 Hz. The frequency range is set by the distribution cabinet for differential configuration according to the load type of each power consumption area and its tolerance to frequency fluctuations.

[0077] Further, as attached Figure 2 As shown, a step diagram of the control method adopted by the bidirectional power quality control system of the intelligent distribution cabinet for distributed power supply is shown.

[0078] Exemplarily, in step S100 , a frequency adjustment unit of a power distribution cabinet is used to standardize the power transmission frequency of each of the plurality of microgrid units.

[0079] More specifically, the frequency standard index f after each independent microgrid standard is calculated using the following formula: st .

[0080]

[0081] In the above formula, f min and f max The lower and upper limits of the transmission frequency set for the user area of a microgrid unit; f U and f LThe upper and lower saturation values are respectively, preferably set to the standard frequency (50Hz or 60Hz)

[0082] ±0.1Hz, so that f U and f L A zero response area is formed between the two frequency components to avoid unnecessary frequent adjustments of the control system to small frequency fluctuations.

[0083] After calculation by formula 2, the control method of the distribution cabinet based on the frequency standard index is as follows:

[0084] P out =P0+K p-st (f st ), formula 3;

[0085] Among them, K p-st () is the frequency standard index f st The control function can be obtained by the original K p () is converted; the frequency standard index f st ∈[-1,1], which means that although multiple microgrid units in the power supply network system may be set with different allowed frequency ranges, if the dynamic coordination adjustment of multiple microgrid units in the power supply network system only independently adopts the difference between the absolute real-time frequency and the standard frequency for dynamic control and adjustment, it will be difficult to coordinate the power quality changes of the entire power supply network system at the same time, and a situation of losing sight of one thing while focusing on another may occur.

[0086] The standardized calculation of Formula 2 is used to convert the actual frequency value of each microgrid unit into a frequency standard index under a unified dimension. Based on the frequency standard index, multiple microgrid units are coordinated and controlled, so that each microgrid can achieve logically consistent dynamic adjustment based on different original frequencies.

[0087] Furthermore, in step S200, a frequency standard index f of a microgrid unit is selected. st As the adjustment basis, the frequency standard index f st Assign to the distribution cabinets of other microgrid units. For example, the frequency standard index f of the selected i-th microgrid unit st(i) When it is 0.1, the frequency standard indexes of the remaining microgrid units are also adjusted to 0.1.

[0088] Furthermore, in step S300, the power distribution cabinet of each microgrid unit adjusts the active power P of the microgrid unit by controlling the d-axis current based on the local frequency standard index. e The output of , which includes executing the following substeps:

[0089] S310: Collect three-phase current and perform coordinate transformation; specifically, measure the three-phase current i inside the microgrid unit a ,i b ,i c and transform it into the d-axis and q-axis current components (i d ,i q );

[0090] S320: Reference d-axis current calculation: According to the expected active power output P e and the current voltage amplitude V, calculate the reference d-axis current i d_ref ;

[0091] S330: The actual d-axis current i d Reference value i d_ref Compare and calculate the error Δe=i d_ref -i d ;

[0092] S340: The distribution cabinet calculates the voltage control signal u based on the error Δe according to the existing control strategy. d ;

[0093] S350: The control signal u d Converted into three-phase voltage instructions, the output voltage is adjusted by the inverter in the distribution cabinet to control the d-axis current i d Approximation reference value i d_ref .

[0094] Preferably, in an exemplary embodiment, for each microgrid unit in the power supply network system, an adjustment weight value is set according to the importance of the application scenario of the microgrid unit, and sequential adjustment is performed on multiple microgrid units based on the adjustment weight value.

[0095] Specifically, when the frequency standard index of a microgrid unit (such as a master node with a high regulation weight) is detected to be rising, indicating excess power at that node, the system initiates a sequential regulation mechanism. Based on the regulation weights assigned to each microgrid unit, a logical link is constructed in descending order of weight, starting with the highest-weighted node and proceeding downwards to synchronize the frequency standard index.

[0096] In the specific control process, as shown in the attached Figure 3 As shown, the distribution cabinet of the microgrid unit 122 with the weight i sets its frequency standard index to the current value f st(i) , and f st(i) The value is passed as the target synchronization index to the next weighted microgrid unit 124 with the weight of i+1. The distribution cabinet of the microgrid unit 124 with the weight of i+1 combines its own current frequency standard index fst(i+1) and the received target index f st(i) , through the optimized control function K p-st () adjusts its active power output so that its own frequency standard index gradually approaches the microgrid unit 122 with the i-th weight.

[0097] Through this sequential adjustment method, the dispatchability of low-weight microgrids can be fully mobilized without disrupting the power quality stability in high-level load areas, achieving orderly convergence of the system's overall frequency standard index, optimizing the distribution and utilization efficiency of electric energy, and improving the stability and response adaptability of the coordinated operation of microgrids.

[0098] Embodiment 2: This embodiment should be understood to include at least all the features of any one of the aforementioned embodiments and to be further improved thereon.

[0099] In an exemplary embodiment, the power supply network system includes three microgrid units, namely:

[0100] Microgrid A: Serving residential areas, with average power quality requirements;

[0101] Microgrid B: Serving the medical station, requiring high frequency stability;

[0102] Microgrid C: Serving commercial electricity consumption areas, medium requirements.

[0103] The operating frequency range allowed for each microgrid is as follows:

[0104] microgrids <![CDATA[Lower frequency limit f min > <![CDATA[Upper frequency limit f max > Current frequency Adjust weight value A 49.2 50.8 50.0 0.6 B 49.7 50.3 49.8 1 C 49.5 50.5 50.0 0.8

[0105] The control system then performs the following adjustment steps:

[0106] First, based on the adjustment weight value, microgrid unit B is used as the reference microgrid unit. Because its service object is a medical station, the power frequency is required to be highly stable, so it is given priority as the frequency target benchmark of the system. Currently, the actual frequency of microgrid unit B is 49.8Hz, which is within the set frequency standard index value f st(B) The value is -0.67, indicating a certain degree of underfrequency. Therefore, the regulation strategy should increase the power generation within the microgrid or reduce the power consumption of the substation, with increasing the frequency as the regulation target.

[0107] At the same time, in the first processing stage, the control system uses this frequency standard index as the adjustment target, and for the other two microgrid units A and C, for microgrid unit C, f st(B) =-0.67 assigned to f st(C) , so that f st(C) =-0.67. Therefore, the distribution cabinet of microgrid unit C is based on the current fst(C) =-0.67, which will correspondingly increase the power generation within the microgrid or reduce the power consumption of the substation to allow more power to be output to the power supply network, thereby assisting the microgrid unit B to meet the power demand. The regulation effect is shown in the attached figure. Figure 4 shown.

[0108] Similarly, in the first processing stage, the frequency standard index of the distribution cabinet of microgrid unit A is also assigned to f st(A) =-0.67, and execute the corresponding adjustment strategy to assist microgrid unit B in meeting the electricity demand.

[0109] Furthermore, in the second processing stage, the frequency standard indexes of the three current microgrid units are calculated respectively. Based on the adjustment weight values, the values are assigned in the following order:

[0110] f st(B) →f st(C) ;

[0111] f st(C) →f st(A) ;

[0112] The corresponding microgrid distribution cabinet executes the regulation strategy to improve the corresponding power quality.

[0113] Preferably, in the second processing stage, each microgrid unit performs the above assignment process at a certain time interval; for example, the assignment process can be updated every 20 seconds or every 60 seconds, until the transmission frequency of each microgrid unit is stable and meets the standard frequency.

[0114] Although the present application has been described above with reference to various embodiments, it will be understood that many changes and modifications may be made without departing from the scope of the present application. That is, the methods, systems, and devices discussed above are examples. Various configurations may omit, replace, or add various processes or components as appropriate. For example, in alternative configurations, the methods may be performed in an order different from that described, and / or various components may be added, omitted, and / or combined. Moreover, features described with respect to certain configurations may be combined in various other configurations, such as different aspects and elements of the configurations may be combined in a similar manner. Furthermore, as technology develops, the elements therein may be updated, i.e., many of the elements are examples and do not limit the scope of the present disclosure or the claims.

[0115] Specific details are given in the description to provide a thorough understanding of the exemplary configurations, including implementations. However, the configurations can be practiced without these specific details. For example, well-known circuits, processes, algorithms, structures, and techniques have been shown without unnecessary detail to avoid obscuring the configurations. This description provides only example configurations and does not limit the scope, applicability, or configurations of the claims. Instead, the foregoing description of the configurations will provide those skilled in the art with an enabling description for implementing the described techniques. Various changes may be made to the function and arrangement of the elements without departing from the spirit or scope of the present disclosure.

[0116] In summary, it is intended that the above detailed description be considered illustrative rather than restrictive, and it should be understood that the above embodiments are intended to be merely illustrative of the present invention and not to limit the scope of protection of the present invention. After reading the contents of the present invention, a skilled person may make various changes or modifications to the present invention, and these equivalent changes and modifications also fall within the scope defined by the claims of the present invention.

Claims

1. A bidirectional power quality control system for intelligent distribution cabinets for distributed power supply, characterized in that: The control system is used to control the operation of multiple microgrid units in the power supply network system; Each microgrid unit includes one or more power generation sources and energy storage devices, and at least one power distribution cabinet; multiple microgrid units are connected to a common DC bus through the configured power distribution cabinet; the power distribution cabinet is used to convert the power input or output of the connected microgrid units operating in AC form into AC / DC, and perform frequency regulation control based on the power quality level of the microgrid units; Each of the power distribution cabinets is equipped with a frequency adjustment unit, and the frequency adjustment unit is configured as follows: Obtain the real-time transmission frequency of the local microgrid unit; Calculating a frequency standard index using the real-time power transmission frequency; Obtain frequency standard index of each microgrid unit in the power supply network system; Based on the local frequency standard index and the frequency standard index of each microgrid unit in the power supply network system, the power generation or load power of the local microgrid unit is adjusted.

2. The control system according to claim 1, wherein: The frequency adjustment unit is configured to calculate a frequency standard index according to the real-time power transmission frequency, and the calculation method is: Among them, f st is the frequency standard index, f is the real-time transmission frequency, f min and f max The lower and upper limits of the transmission frequency set for the user area of the microgrid unit; f U and f L are the upper and lower saturation values, respectively; The above calculation method is used to normalize the real-time frequency to a control index between [-1, 1].

3. The control system according to claim 1, wherein: In the control system, a regulation weight value is set for each microgrid unit; based on the regulation weight value of the microgrid unit, a frequency standard index of at least one microgrid unit is selected as a regulation benchmark for power quality; The power distribution cabinets of the remaining microgrid units adjust the internal power quality of the microgrid units to which they belong based on the adjustment benchmark.

4. A bidirectional power quality control method for intelligent distribution cabinets for distributed power supply, characterized in that: The control method is applied to a bidirectional power quality control system for an intelligent distribution cabinet for distributed power supply as described in any one of claims 1 to 3; the control method comprises the following steps: S100: Standardize the transmission frequency in the microgrid unit and convert the transmission frequency into a frequency standard index f st ; S200: Select a frequency standard index f of a microgrid unit st As the adjustment benchmark, the frequency standard index f st Assign to the distribution cabinet of one or more other microgrid units; S300: The power distribution cabinet of each microgrid unit adjusts the active power P of the microgrid unit by controlling the d-axis current based on the local frequency standard index. e Output.

5. The control method according to claim 4, wherein: The control method also includes performing two processing stages; wherein, In the first processing stage, a frequency standard index of a microgrid unit is selected as a regulation benchmark, and the regulation benchmark is sent to the distribution cabinets of the remaining microgrid units. Each distribution cabinet performs power quality regulation for the corresponding microgrid unit based on the same regulation benchmark; In the second processing stage, following the first processing stage, the adjustment weight values of each microgrid unit are sorted in descending order, and the frequency standard index f of the i-th microgrid unit is st(i) Send it to the i+1th microgrid unit; thereafter, the i+1th microgrid unit combines and analyzes the local frequency standard index f st(i+1) With f st(i) , thereby regulating the power quality of the local microgrid unit.

6. The control method according to claim 5, wherein: In the first processing stage, a frequency standard index of a microgrid unit is selected as a regulation benchmark based on one of the following conditions: When there is only one microgrid unit, the frequency standard index f st When ≠0, this microgrid unit is selected; When there are two or more microgrid units, the frequency standard index f st When ≠0, the microgrid unit with the highest adjustment weight value is selected.

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