A two-way power quality control system for a distributed power supply-oriented intelligent power distribution cabinet

Abstract

The application relates to a bidirectional power quality control system of a smart power distribution cabinet facing distributed power supply and a control method thereof. The control system comprises multiple micro-grid units, each of which is provided with a power distribution cabinet, and the multiple power distribution cabinets are connected to a common DC bus, are used for converting AC and DC power of respective micro-grids, and perform frequency regulation control based on power quality requirements. Each power distribution cabinet is provided with a frequency regulation unit used for collecting local power transmission frequency and calculating a frequency standard index. The system determines a regulation sequence according to the frequency standard indexes of the multiple micro-grid units and preset regulation weight values of the multiple micro-grid units, preferentially takes the frequency standard index of a high-weight node as a regulation reference, and adjusts active output of the remaining micro-grids in a sequential transmission mode.

Description

Technical Field

[0001] This invention belongs to the field of power control technology, and more specifically, relates to a two-way power quality control system for intelligent distribution cabinets for distributed power supply. Background Technology

[0002] In distributed power supply systems, microgrids, as regional independent energy supply units, possess characteristics such as self-generation, self-balancing, and self-control. They have been widely applied in offline power grids for parks, communities, data centers, and remote areas powered by renewable energy. Multiple microgrid units are connected to a common DC bus via distribution equipment to form a multi-node parallel structure, which helps improve the system's power supply flexibility and the proportion of renewable energy integration. However, due to the different service targets of each microgrid, their power quality requirements vary significantly, especially in terms of frequency stability, where different load levels have inconsistent tolerances for frequency regulation accuracy. Traditional microgrid control methods often aim for a unified frequency, ignoring differences between nodes, which can easily lead to instability in certain critical load areas due to frequency disturbances. Furthermore, current regulation and control are mostly static responses, lacking a dynamic quantitative description of the system's internal frequency state, making it difficult to achieve hierarchical and orderly regulation among multiple nodes. Therefore, there is an urgent need for a standardized index that can characterize the frequency state of a microgrid, combined with the load level and weight of each node, to implement a coordinated frequency control strategy within the system, thereby enhancing the dynamic adaptability and power quality assurance capabilities of multi-microgrid systems.

[0003] A review of relevant publicly available technologies reveals several key solutions. CN116780639B proposes a distributed photovoltaic grid-connected control method, which determines subsequent processing strategies for photovoltaic modules by acquiring transient electrical parameter values ​​when switches trip in the distribution network. EP3079027A4 proposes a monitoring system for a distributed generation air conditioning system, which calculates the operating status of each component in the air conditioning system by arranging multiple monitoring elements in the air conditioning ducts to control the power transmission strategy of the power generation modules. US20170012428A1 proposes a system for effective operational control between distributed power sources, which provides virtual current in the same direction as the forward power flow by setting up a virtual current output unit.

[0004] The above technical solutions all propose various control methods or systems for distributed power supply systems, aiming to improve the power supply quality or utilization efficiency of distributed systems. However, for power consumption scenarios in microgrids where actual power consumption has specific requirements, there is still a need to propose relevant control methods.

[0005] The foregoing description of the background art is intended only to facilitate understanding of the invention. This description does not endorse or acknowledge any common general knowledge in the materials mentioned. Summary of the Invention

[0006] The purpose of this invention is to provide a bidirectional power quality control system and method for intelligent distribution cabinets in distributed power supply. The control system includes multiple microgrid units, each equipped with a distribution cabinet. These distribution cabinets are connected to a common DC bus and are used to convert AC and DC power for their respective microgrids, and to perform frequency regulation control based on power quality requirements. Each distribution cabinet has a frequency adjustment unit for acquiring the local transmission frequency and calculating the frequency standard index. The system determines the adjustment sequence based on the frequency standard indices of the multiple microgrid units and their preset adjustment weight values, prioritizing the frequency standard index of high-weight nodes as the adjustment benchmark, and adjusting the active power output of the remaining microgrids level by level using a sequential transmission method.

[0007] The present invention adopts the following technical solution: a two-way power quality control system for intelligent distribution cabinets for distributed power supply, wherein the control system is used to control the operation of multiple microgrid units in the power supply network system;

[0008] Each of the microgrid units includes one or more power sources and energy storage devices, as well as at least one distribution cabinet; multiple microgrid units are connected to a common DC bus through the configured distribution cabinet; the distribution cabinet is used to perform AC-DC conversion on the power input or output of the connected, AC-operated microgrid units, and to 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, which is configured as follows:

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

[0011] The frequency standard index is calculated using the real-time power transmission frequency.

[0012] Obtain the 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 the frequency standard index using the real-time transmission frequency, and the calculation method is as follows:

[0015]

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

[0017] The above calculation method standardizes the real-time frequency to a control index between [-1, 1].

[0018] Preferably, in the control system, a regulation weight value is set for each microgrid unit; based on the regulation weight value of the microgrid unit, the frequency standard index of at least one microgrid unit is selected as the power quality regulation benchmark; the distribution cabinets of the remaining microgrid units adjust the internal power quality of their respective microgrid units based on the regulation benchmark.

[0019] Furthermore, a bidirectional power quality control method for intelligent distribution cabinets oriented towards distributed power supply is proposed. This control method is applied to the aforementioned bidirectional power quality control system for intelligent distribution cabinets oriented towards distributed power supply. The control method includes the following steps:

[0020] S100: Standardizes the transmission frequency in the microgrid unit, converting the transmission frequency into the frequency standard index f. st ;

[0021] S200: Select the frequency standard index f of a microgrid unit st As an adjustment benchmark, the frequency standard index f st The value is assigned to the distribution cabinet of one or more other microgrid units;

[0022] S300: The distribution cabinet of each microgrid unit regulates 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 .

[0023] Preferably, the control method further includes performing two processing stages; wherein,

[0024] In the first processing stage, the frequency standard index of a microgrid unit is selected as the adjustment benchmark, and the adjustment benchmark is sent to the distribution cabinets of the remaining microgrid units. Each distribution cabinet performs power quality adjustment on the corresponding microgrid unit based on the same adjustment 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) The data is sent to the (i+1)th microgrid unit; subsequently, the (i+1)th microgrid unit combines the analysis with the local frequency standard index f. st(i+1) with f st(i)This allows for the regulation of power quality in local microgrid units.

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

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

[0028] When there are two or more microgrid units, the frequency standard index f st When the value is not equal to 0, select the microgrid unit with the highest adjustment weight value.

[0029] The beneficial effects achieved by this invention are:

[0030] 1. This technical solution introduces a frequency standard index as a unified dimensionless control indicator, which can accurately reflect the real-time frequency status of each microgrid unit and perform differentiated adjustments based on the power quality level of each microgrid. Compared with traditional unified frequency control methods, it can more effectively ensure frequency stability in highly sensitive load areas and improve system reliability and service capabilities.

[0031] 2. The control system of this technical solution constructs a control priority chain by setting the adjustment weight values ​​of the microgrid units, thereby realizing an orderly power adjustment process from the master control node to the slave nodes. This sequential conduction method can avoid the disorderly propagation of frequency anomalies within the system, optimize the allocation of adjustment resources, and effectively improve 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, featuring independent structure, low communication requirements, and modular algorithms. This system can be flexibly deployed in various types of microgrid scenarios, adapting to different power load levels and regulation strategies, and has good engineering application prospects.

[0033] 4. The control system of this technical solution adopts a modular design in both hardware and software. Each working module and component of the hardware part, as well as the instructions, parameters and algorithms of the software part, can be easily replaced and / or upgraded later, thereby reducing the construction cost and maintenance cost of this system. Attached Figure Description

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

[0035] Explanation of reference numerals: 110 - Microgrid unit; 120 - 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 described in this invention;

[0037] Figure 2 This is a flowchart illustrating the steps of the control method described in an embodiment of the present invention;

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

[0039] Figure 4 This is a schematic diagram of the frequency and power output curves during the adjustment process of two microgrid units in an embodiment of the present invention. Detailed Implementation

[0040] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to its embodiments. It should be understood that the specific embodiments described herein are for illustrative purposes only and are not intended to limit the invention. Other systems, methods, and / or features of this embodiment will become apparent to those skilled in the art after reviewing the following detailed description. All such additional systems, methods, features, and advantages are intended to be included within this specification, within the scope of the invention, and protected by the appended claims. Further features of the disclosed embodiments are described in the following detailed description, and these features will become apparent from the following detailed description.

[0041] In the accompanying drawings of this invention, the same or similar reference numerals correspond to the same or similar components. In the description of this invention, it should be understood that if terms such as "upper," "lower," "left," and "right" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, they are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or component referred to must have a specific orientation. Because the invention is constructed and operated in a specific orientation, the terms describing positional relationships in the drawings are for illustrative purposes only and should not be construed as limiting this patent. Those skilled in the art can understand the specific meaning of the above terms according to the specific circumstances.

[0042] Example 1: By way of example, a two-way power quality control system for intelligent distribution cabinets for distributed power supply is proposed. The control system is used to control the operation of multiple microgrid units in the power supply network system.

[0043] Each of the microgrid units includes one or more power sources and energy storage devices, as well as at least one distribution cabinet; multiple microgrid units are connected to a common DC bus through the configured distribution cabinet; the distribution cabinet is used to perform AC-DC conversion on the power input or output of the connected, AC-operated microgrid units, and to 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, which is configured as follows:

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

[0046] The frequency standard index is calculated using the real-time power transmission frequency.

[0047] Obtain the 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 the frequency standard index using the real-time transmission frequency, and the calculation method is as follows:

[0050]

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

[0052] The above calculation method standardizes the real-time frequency to a control index between [-1, 1].

[0053] Preferably, in the control system, a regulation weight value is set for each microgrid unit; based on the regulation weight value of the microgrid unit, the frequency standard index of at least one microgrid unit is selected as the power quality regulation benchmark; the distribution cabinets of the remaining microgrid units adjust the internal power quality of their respective microgrid units based on the regulation benchmark.

[0054] Furthermore, a bidirectional power quality control method for intelligent distribution cabinets oriented towards distributed power supply is proposed. This control method is applied to the aforementioned bidirectional power quality control system for intelligent distribution cabinets oriented towards distributed power supply. The control method includes the following steps:

[0055] S100: Standardizes the transmission frequency in the microgrid unit, converting the transmission frequency into the frequency standard index f. st ;

[0056] S200: Select the frequency standard index f of a microgrid unit st As an adjustment benchmark, the frequency standard index f st The value is assigned to the distribution cabinet of one or more other microgrid units;

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

[0058] Preferably, the control method may further include execution in two processing phases; wherein,

[0059] In the first processing stage, the frequency standard index of a microgrid unit is selected as the adjustment benchmark, and the adjustment benchmark is sent to the distribution cabinets of the remaining microgrid units. Each distribution cabinet performs power quality adjustment on the corresponding microgrid unit based on the same adjustment 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) The data is sent to the (i+1)th microgrid unit; subsequently, the (i+1)th microgrid unit combines the analysis with the local frequency standard index f. st(i+1) with f st(i) This allows for the regulation of power quality in local microgrid units.

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

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

[0063] When there are two or more microgrid units, the frequency standard index f st When the value is not equal to 0, select the microgrid unit with the highest adjustment weight value.

[0064] In the following, 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 can adjust or substitute the specific forms without departing from the spirit and essence of the present invention.

[0065] The control system proposed in this technical solution is applicable to distributed power supply systems in remote residential communities. Specifically, it includes a control method based on intelligent distribution cabinets. This method dynamically adjusts the output frequency or voltage parameters of each microgrid unit according to the power quality requirements within each microgrid unit's area, thereby optimizing output quality for the main grid and ensuring input quality for end-loads. The system determines 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 regulates the effective output power, and coordinates the operating status of multiple microgrids through a frequency / voltage standardization mechanism, thus achieving stable bidirectional power quality control in a multi-microgrid interconnected structure. The following will describe in detail the composition of the multi-frequency control system for multiple independent microgrids in this embodiment of the invention, with reference to the accompanying drawings.

[0066] As attached Figure 1 The following diagram illustrates an exemplary implementation of the control system. In this exemplary implementation, the distributed power supply network system includes three microgrid units 110 (labeled 110a, 110b, and 110c for ease of description) and three distribution cabinets 120 (labeled 120a, 120b, and 120c for ease of description) connected to their respective microgrid units. However, this technical solution does not limit the number of microgrid units; the number of microgrid units is merely illustrative and provided for ease of explanation.

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

[0068] For example, each microgrid unit 110 is an independently deployed local power supply unit, which may typically include one or more distributed power 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 residential loads.

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

[0070] Each distribution cabinet 120 is located at the transmission interface of the corresponding microgrid unit to handle bidirectional power transmission and conversion between the DC bus 130 and the microgrid unit 110. The distribution cabinet 120 includes functions for converting AC power generated within the microgrid unit (e.g., AC power generated by wind power generation) into DC power and outputting it to the DC grid connection line; conversely, it can also convert received DC power back into AC power to supply the electrical appliances within the microgrid unit. Furthermore, the distribution cabinet 120 also has a frequency coordination control function, which can dynamically adjust the power load range based on the frequency operation of the substation it serves.

[0071] Preferably, each intelligent distribution cabinet is equipped with a frequency adjustment unit (not shown in the figure). The frequency adjustment unit interacts with the distribution cabinets of adjacent microgrid units via communication line 140. Each 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 improve the coordination and 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 power absorbed by the load side is affected by power balance. Specifically, 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 remains basically stable at a set value, such as 50Hz.

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

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

[0075] In Equation 1, P out P0 represents the active power output of the microgrid unit controlled by the current distribution cabinet; P0 is the reference power output of the system at the reference frequency (commonly 50Hz or 60Hz), which is the default output under the condition of no frequency deviation; f is the actual operating frequency of the current microgrid. ref That is, the reference frequency; K P () represents the adjustment strategy function of the power distribution cabinet, which can be programmed by relevant technical personnel based on f. refThe deviation from the actual operating frequency f is used to adjust and control the active power output value. Furthermore, different microgrid units have different power consumption equipment and power quality requirements in their power supply areas. For example, residential electricity demand is low, allowing for larger power quality fluctuations and slower power quality adjustment responses; while applications such as data centers and medical facilities require higher power quality and faster power quality adjustment responses. Therefore, in the preferred embodiment, the adjustment strategy function K of each distribution cabinet is... P () can also be designed specifically to adapt to the requirements of different microgrid areas, such as adjusting the strategy function K P () can be a proportional or integral control algorithm function to ensure a stable dynamic response of the system.

[0076] Preferably, in an exemplary embodiment, this 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 these ranges as the basis for the microgrid's participation in system frequency coordination. Specifically, based on the specific power consumption conditions within each microgrid unit, different power quality requirements are set for each unit's distribution area. For example, microgrid unit 110a can be set to a wider frequency tolerance of 59.4–60.6 Hz, microgrid unit 110b can be set to a medium regulation range of 59.7–60.3 Hz, and microgrid unit 110c can be set to a precise regulation range of 59.5–60.5 Hz. The frequency range is set by the distribution cabinet according to the load type of each power consumption area and its tolerance for frequency fluctuations.

[0077] Further details are attached. Figure 2 The diagram illustrates the steps of the control method employed in the bidirectional power quality control system for intelligent distribution cabinets designed for distributed power supply.

[0078] For example, in step S100, the transmission frequency of each of the multiple microgrid units is standardized using the frequency adjustment unit of the distribution cabinet.

[0079] More specifically, the frequency standard index f of 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 LThese are the upper and lower saturation values, respectively, and can preferably be set to a standard frequency (50Hz or 60Hz).

[0082] ±0.1Hz, making f U and f L This creates a zero-response region, preventing the control system from making unnecessary frequent adjustments to minor frequency fluctuations.

[0083] After calculation using Equation 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 Equation 3;

[0085] Among them, K p-st () represents the frequency standard index f st The control function can be obtained through the original K. p The result obtained after conversion ( ); frequency standard index f st The meaning of ∈[-1,1] is that although multiple microgrid units in the power supply network system may be set with different allowable frequency ranges, if the dynamic coordination adjustment of multiple microgrid units in the power supply network system is only dynamically controlled and adjusted by the difference between the absolute real-time frequency and the standard frequency, it is difficult to coordinate the power quality changes of the entire power supply network system at the same time, and there may be a situation where one thing is taken into account but another is not.

[0086] Using Equation 2, the actual frequency values ​​of each microgrid unit are converted into a frequency standard index under a unified dimension. Based on the frequency standard index, coordinated control is carried out among multiple microgrid units, 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 is selected for a microgrid unit. st As an adjustment benchmark, the frequency standard index f st The value is assigned 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 the value is 0.1, the frequency standard index of the remaining microgrid units is also adjusted to 0.1.

[0088] Furthermore, in step S300, the 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 includes the following sub-steps:

[0089] S310: Acquire three-phase current and perform coordinate transformation; specifically, measure the three-phase current i inside the microgrid unit. a i b i c And through Clarke transform and Park transform, it is converted into d-axis and q-axis current components in a rotating coordinate system (i d i q );

[0090] S320: Reference d-axis current calculation: based on the desired active power output P e Given 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: Control signal u d The command is converted into a three-phase voltage command, and the output voltage is adjusted by the inverter in the distribution cabinet, thereby controlling the d-axis current i. d Approximating the reference value i d_ref .

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

[0095] Specifically, when an upward trend in the frequency standard index is detected in a microgrid unit (e.g., a master node with a high adjustment weight), indicating that the node has excess power, the system initiates a sequential adjustment mechanism. Based on the adjustment weights set for each microgrid unit, a logical link is constructed with weights arranged in descending order, and frequency standard index synchronization control is performed sequentially downwards, starting from the node with the highest weight.

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

[0097] This sequential adjustment method can fully mobilize the dispatchability of low-weight microgrids without disrupting the power quality stability of high-load areas, thereby achieving orderly convergence of the overall system frequency standard index, optimizing the distribution and utilization efficiency of power, and improving the stability and responsiveness of microgrid collaborative operation.

[0098] Example 2: This example should be understood as including at least all the features of any of the foregoing examples, and further improving upon them.

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

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

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

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

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

[0104] microgrids <![CDATA[Lower frequency limit f min > <![CDATA[Upper frequency limit f max > Current frequency Adjusting weight values 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, microgrid unit B is selected as the reference microgrid unit based on the adjustment weight value. Since its service target is a medical station, requiring highly stable power frequency, it is prioritized as the system's frequency target benchmark. Currently, the actual frequency of microgrid unit B is 49.8Hz, and its frequency standard index value f falls within the set range. st(B) A value of -0.67 indicates a certain degree of underfrequency operation. Therefore, the regulation strategy should be to increase the power generation within the microgrid or reduce the power consumption of the distribution area, with the goal of increasing the frequency.

[0107] Simultaneously, in the first processing stage, the control system uses this frequency standard index as the adjustment target. For the other two microgrid units, A and C, for microgrid unit C, f... st(B) =-0.67 assigned to f st(C) , making 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 capacity within the microgrid or reduce the power consumption of the distribution area, allowing more power to be output to the power grid, thereby assisting microgrid unit B in meeting its power demand. The adjustment effect is shown in the attached figure. Figure 4 As shown.

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

[0109] Furthermore, in the second processing stage, the frequency standard index of each of the three microgrid units is calculated. 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 cabinets then implement regulation strategies to improve the corresponding power quality.

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

[0114] While this application has been described above with reference to various embodiments, it should be understood that many changes and modifications can be made without departing from the scope of this application. That is, the methods, systems, and devices discussed above are examples. Various configurations can be appropriately omitted, substituted, or added to various processes or components. For example, in alternative configurations, methods can be performed in a different order than those described, and / or various components can be added, omitted, and / or combined. Moreover, features described with respect to certain configurations can be combined in various other configurations, such as different aspects and elements of the configuration can be combined in a similar manner. Furthermore, the elements therein can be updated as the technology develops; that is, many elements are examples and do not limit the scope of this disclosure or the claims.

[0115] Specific details are provided in the specification to offer a thorough understanding of exemplary configurations, including implementations. However, 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 configuration. This description provides only exemplary configurations and does not limit the scope, applicability, or configuration of the claims. Rather, the foregoing description of the configurations will provide those skilled in the art with an enabling description for implementing the described techniques. Various changes can be made to the function and arrangement of the elements without departing from the spirit or scope of this disclosure.

[0116] In summary, the above detailed description is intended to be illustrative rather than restrictive, and it should be understood that these embodiments are for illustrative purposes only and not for limiting the scope of protection of the invention. After reading the description of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent changes and modifications also fall within the scope defined by the claims of this 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 of the microgrid units includes one or more power sources and energy storage devices, as well as at least one distribution cabinet; multiple microgrid units are connected to a common DC bus through the configured distribution cabinet; the distribution cabinet is used to perform AC-DC conversion on the power input or output of the connected, AC-operated microgrid units, and to 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, which is configured as follows: Obtain the real-time transmission frequency of the local microgrid unit; The frequency standard index is calculated using the real-time power transmission frequency. Obtain the 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, adjust the power generation or load power of the local microgrid unit. The frequency adjustment unit is configured to calculate the frequency standard index using the real-time transmission frequency, the calculation method being... for: ， Among them, f st Here, f is the frequency standard index, and f is the real-time transmission frequency. min and f max The lower and upper limits of the transmission frequency set for the user areas of the microgrid unit; f U and f L These are the upper and lower saturation values, respectively. The above calculation method standardizes the real-time frequency to a control index between [-1, 1]. In the control system, a regulation weight value is set for each microgrid unit; based on the microgrid unit's... The adjustment weight value selects at least one microgrid unit's frequency standard index as the power quality adjustment benchmark; the distribution cabinets of the remaining microgrid units adjust the internal power quality of their respective microgrid units based on the adjustment benchmark.

2. 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 intelligent distribution cabinets oriented towards distributed power supply as described in claim 1; the control method includes the following steps: S100: Standardizes the transmission frequency in the microgrid unit, converting the transmission frequency into the frequency standard index f. st ; S200: Select the frequency standard index f of a microgrid unit st As an adjustment benchmark, the frequency standard index f st The value is assigned to the distribution cabinet of one or more other microgrid units; S300: The distribution cabinet of each microgrid unit regulates 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 .

3. The control method as described in claim 2, characterized in that, The control method further includes performing two processing phases; wherein... In the first processing stage, the frequency standard index of a microgrid unit is selected as the adjustment benchmark, and the adjustment benchmark is sent to the distribution cabinets of the remaining microgrid units. Each distribution cabinet performs power quality adjustment on the corresponding microgrid unit based on the same adjustment 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) The data is sent to the (i+1)th microgrid unit; subsequently, the (i+1)th microgrid unit combines the analysis with the local frequency standard index f. st(i+1) with f st(i) This allows for the regulation of power quality in local microgrid units.

4. The control method as described in claim 3, characterized in that, In the first processing stage, a frequency standard index of a microgrid unit is selected as the adjustment benchmark based on one of the following conditions: When there is only one microgrid unit, the frequency standard index f st When ≠0, select this microgrid unit; When there are two or more microgrid units, the frequency standard index f st When the value is not equal to 0, select the microgrid unit with the highest adjustment weight value.

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