A power distribution network partition flexible interconnection regulation method and device based on E-SOP

Abstract

The application discloses a power distribution network partition flexible interconnection regulation method and device based on E-SOP, relates to the technical field of power distribution networks, and establishes a same-area flexible interconnection system architecture. A plurality of feeder lines with a distance shorter than a preset distance, a distributed power source penetration rate higher than a preset penetration rate, a load density higher than a preset density, and different time characteristics are used to regulate the same-area flexible interconnection system power flow by using energy storage type flexible soft switches connected at the end of the feeder lines. The application establishes a cross-area flexible interconnection system architecture. Different regional power distribution feeder lines with a distance longer than a preset distance and a large power supply and demand difference greater than a difference threshold are interconnected with other regional power grids through energy storage type flexible soft switches and DC lines for long-distance interconnection of cross-area low-voltage AC feeder lines and other regional power grids, thereby solving the technical problems of power flow reverse transmission, voltage out-of-limit and insufficient distributed power source consumption capacity caused by large-scale access of distributed power sources in the same-area and cross-area power grids.

Description

Technical Field

[0001] This invention relates to the field of power distribution network technology, and in particular to a method and apparatus for flexible interconnection and control of power distribution network zones based on E-SOP (Soft OpenPoints with Energy Storage). Background Technology

[0002] The integration of distributed power sources such as wind and solar power into the distribution network poses challenges to the network's operational efficiency and stability. The intermittency and randomness of distributed power sources can lead to problems such as voltage exceeding limits and power flow reversal, affecting the safe operation of the distribution network. Traditional solutions, such as distribution network upgrades, energy storage system configurations, and demand-side management, can alleviate these problems to some extent, but they still have certain limitations: distribution network upgrades are costly and time-consuming; energy storage system configurations are not only expensive but also involve large land areas and safety hazards; and demand-side management relies on user participation, making its implementation effectiveness uncertain. Against this backdrop, Soft Open Points (SOPs), as an emerging solution, have gradually become a research hotspot due to their high flexibility and economy. By precisely controlling active power exchange and compensating for reactive power, SOPs provide real-time, fine-grained power flow regulation capabilities, effectively improving the operational efficiency of the distribution network.

[0003] Traditional System Operations (SOPs) primarily achieve power flow regulation on a spatial scale by controlling converters. However, their regulation capability is limited by converter capacity and operational constraints, failing to address the problems of power flow backflow, voltage overshooting, and insufficient distributed generation absorption capacity caused by large-scale distributed generation integration in intra-regional and inter-regional power grids. Therefore, how to solve the problems of power flow backflow, voltage overshooting, and insufficient distributed generation absorption capacity caused by large-scale distributed generation integration in intra-regional and inter-regional power grids is a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0004] This invention provides a distribution network zonal flexible interconnection control method and device based on E-SOP, which is used to solve the technical problems of power flow backflow, voltage over-limit and insufficient distributed power absorption capacity caused by the large-scale access of distributed power sources in the same area and cross-area power grids.

[0005] In view of this, the first aspect of the present invention provides a method for flexible interconnection and control of distribution network zones based on E-SOP, comprising:

[0006] Establish a flexible interconnection system architecture in the same area. Several feeders that are close to the preset distance, have a higher than the preset penetration rate of distributed power sources, have a higher than the preset load density, and have different time characteristics are connected to the end of the feeders and have integrated energy storage flexible soft switches to regulate the power flow of the flexible interconnection system in the same area. This allows each feeder in the flexible interconnection system in the same area to jointly bear and collaboratively absorb the grid-connected power of renewable energy.

[0007] Establish a cross-regional flexible interconnection system architecture, and connect the power distribution feeders of different regions that are far from the preset distance and whose power supply and demand differences are greater than the difference threshold through energy storage flexible soft switches and DC lines, so as to achieve long-distance interconnection between the cross-regional low-voltage AC feeders and other regional power grids.

[0008] Optionally, by utilizing a flexible soft switch with integrated energy storage connected to the end of the feeder to regulate the power flow of the flexible interconnected system in the same area, the feeders of the flexible interconnected system in the same area can jointly bear and collaboratively absorb the grid-connected power of renewable energy, including:

[0009] Obtain the remaining capacity of the feeder and energy storage systems of the flexible interconnection system in the same area;

[0010] Based on the feeders of the flexible interconnection system in the same area and the remaining capacity of the energy storage system, the operation modes of the flexible interconnection system in the same area are divided.

[0011] Based on the operating mode of the flexible interconnection system in the same area, a corresponding control strategy is adopted. By using a flexible soft switch with energy storage integrated at the end of the feeder, the voltage of the flexible interconnection system in the same area is regulated, so that each feeder of the flexible interconnection system in the same area can jointly undertake and collaboratively absorb the grid-connected power of renewable energy.

[0012] Optionally, the operating modes of the flexible interconnection system in the same area include the first operating mode, the second operating mode, the third operating mode, the fourth operating mode, and the fifth operating mode;

[0013] The first operating mode is that all feeders and energy storage systems of the flexible interconnection system in the same area have sufficient spare capacity;

[0014] The second operating mode is that one of the feeders of the flexible interconnection system in the same area has insufficient remaining capacity, while the remaining capacity of the other feeders and the remaining capacity of the energy storage system are sufficient.

[0015] The third operating mode is that the remaining capacity of two feeders in the flexible interconnection system in the same area is insufficient, while the remaining capacity of the other feeders and the remaining capacity of the energy storage system are sufficient; or the remaining capacity of three or more feeders in the flexible interconnection system in the same area is insufficient, but there is at least one feeder with sufficient remaining capacity and the remaining capacity of the energy storage system.

[0016] The fourth operating mode is characterized by insufficient remaining capacity of all feeders in the flexible interconnection system within the same area, while sufficient remaining capacity of the energy storage system.

[0017] The fifth operating mode is when all feeders and energy storage systems in the same area of ​​the flexible interconnection system have insufficient remaining capacity.

[0018] Optionally, the preset control strategy for the inter-regional flexible interconnection power distribution system is as follows:

[0019] Obtain the remaining capacity of the feeder and energy storage systems of the inter-regional flexible interconnection system;

[0020] Based on the feeders of the inter-regional flexible interconnection system and the remaining capacity of the energy storage system, the operation modes of the inter-regional flexible interconnection system are divided.

[0021] Based on the operation mode of the inter-regional flexible interconnection system, corresponding control strategies are adopted to achieve long-distance interconnection between inter-regional low-voltage AC feeders and other regional power grids through energy storage-type flexible soft switches and DC lines.

[0022] Optionally, the operation modes of the cross-regional flexible interconnection system include the sixth operation mode, the seventh operation mode, the eighth operation mode, the ninth operation mode, and the tenth operation mode;

[0023] The sixth operating mode ensures that all feeders and energy storage systems in the cross-regional flexible interconnection system have sufficient spare capacity;

[0024] The seventh operating mode is that the remaining capacity of the feeder and the remaining capacity of the energy storage system in the local area of ​​the cross-regional flexible interconnection system are sufficient, while the remaining capacity of at least one feeder in the cross-regional system is insufficient.

[0025] The eighth operating mode is that during the process of adjusting the voltage of the feeder node in the cross-regional flexible interconnection system, the voltage of the common connection point of the feeder in this region may exceed the voltage limit.

[0026] The ninth operating mode is that during the process of adjusting the voltage of the feeder nodes in the cross-regional flexible interconnection system, all feeders in this region may experience a risk of voltage exceeding the limit at the common connection point of all feeders in this region.

[0027] The tenth operating mode is characterized by insufficient remaining capacity in all feeders and energy storage systems of the cross-regional flexible interconnection system;

[0028] The operation modes of the cross-regional flexible interconnection system follow a strict priority of judgment. The operation modes are mutually exclusive, and the judgment order from first to last is: sixth operation mode, seventh operation mode, eighth operation mode, ninth operation mode, and tenth operation mode.

[0029] Optionally, the control strategy corresponding to the first operating mode is as follows: one port of the energy storage flexible soft switch adopts a DC voltage-reactive power control strategy to maintain the DC bus voltage stability, while the other ports of the energy storage flexible soft switch and the energy storage system are in standby mode and do not participate in voltage regulation.

[0030] The control strategy corresponding to the second operating mode is as follows: based on the remaining capacity of the feeder of the flexible interconnection system in the same area and the remaining capacity of the energy storage system, the active power-reactive power control strategy and the DC voltage-reactive power control strategy are respectively adopted for each port of the energy storage type flexible soft switch to maintain the stability of the DC bus voltage.

[0031] The control strategy corresponding to the third operating mode is as follows: the two ports of the energy storage type flexible soft switch of the flexible interconnection system in the same area adopt the active power-reactive power control strategy, and the remaining ports adopt the DC voltage-reactive power control strategy to maintain the DC bus voltage stability. The energy storage system does not participate in the regulation.

[0032] The control strategy corresponding to the fourth operating mode is as follows: the two ports of the energy storage type flexible soft switch of the flexible interconnection system in the same area adopt the active power-reactive power control strategy, and the remaining ports adopt the DC voltage-reactive power control strategy to maintain the DC bus voltage stability. The energy storage system is adjusted to the preset power reference value.

[0033] The power control strategy corresponding to the fifth operating mode is as follows: all energy storage systems in the flexible interconnection system in the same area exit voltage regulation and reduce the grid-connected power of distributed power sources on the feeder in preset steps.

[0034] Optionally, the control strategy corresponding to the sixth operating mode is as follows: one energy storage flexible soft switch port in the local area of ​​the cross-regional flexible interconnection system controls the DC voltage to the DC voltage reference value to maintain the DC bus voltage stability, while the other energy storage flexible soft switch ports in the local area and the cross-regional energy storage flexible soft switch ports and the energy storage system are in standby mode and do not participate in voltage regulation.

[0035] The control strategy corresponding to the seventh operating mode is as follows: the cross-regional energy storage flexible soft switch port of the cross-regional flexible interconnection system controls the voltage of the common connection point, one energy storage flexible soft switch port in this region controls the DC bus voltage, and the other energy storage flexible soft switch ports and energy storage system do not participate in voltage regulation;

[0036] The control strategy corresponding to the eighth operating mode is as follows: one port of the local energy storage type flexible soft switch of the cross-regional flexible interconnection system controls the DC voltage as the DC reference voltage and absorbs the excess power of the local feeder and the cross-regional feeder. The other ports of the local energy storage type flexible soft switch of the cross-regional flexible interconnection system switch from controlling the DC voltage to controlling the voltage of the local feeder. The energy storage system of the cross-regional flexible interconnection system does not participate in voltage regulation.

[0037] The control strategy corresponding to the ninth operating mode is as follows: the energy storage system of the cross-regional flexible interconnection system participates in voltage regulation, one port of the local energy storage type flexible soft switch of the cross-regional flexible interconnection system controls the DC voltage as the DC reference voltage and absorbs the excess power on the local feeder, and the other ports of the local energy storage type flexible soft switch switch are switched from controlling the DC voltage to controlling the voltage of the local feeder.

[0038] The control strategy corresponding to the tenth operating mode is as follows: the energy storage system of the inter-regional flexible interconnection system does not participate in voltage regulation, and the grid-connected power of the distributed power source on the feeder of the inter-regional flexible interconnection system is reduced by a preset increment.

[0039] A second aspect of the present invention provides a distribution network zonal flexible interconnection control device based on E-SOP, comprising:

[0040] The same-area control module is used to establish the same-area flexible interconnection system architecture. It connects several feeders that are close to the preset distance, have a higher than the preset penetration rate of distributed power sources, have a higher than the preset load density, and have different time characteristics. It uses energy storage-type flexible soft switches connected to the end of the feeders to regulate the power flow of the same-area flexible interconnection system, so that each feeder of the same-area flexible interconnection system can jointly bear and collaboratively absorb the grid-connected power of renewable energy.

[0041] The cross-regional control module is used to establish a cross-regional flexible interconnection system architecture. It connects power distribution feeders in different regions that are far apart from a preset distance and whose power supply and demand differences are greater than the difference threshold, through energy storage-type flexible soft switches and DC lines, to achieve long-distance interconnection between cross-regional low-voltage AC feeders and other regional power grids.

[0042] Optionally, the same-zone control module is specifically used for:

[0043] Establish a flexible interconnection system architecture in the same area, connecting several feeders that are close to the preset distance, have a higher than the preset penetration rate of distributed power sources, have a higher than the preset load density, and have different time characteristics;

[0044] Obtain the remaining capacity of the feeder and energy storage systems of the flexible interconnection system in the same area;

[0045] Based on the feeders of the flexible interconnection system in the same area and the remaining capacity of the energy storage system, the operation modes of the flexible interconnection system in the same area are divided.

[0046] Based on the operating mode of the flexible interconnection system in the same area, a corresponding control strategy is adopted. By using a flexible soft switch with energy storage integrated at the end of the feeder, the voltage of the flexible interconnection system in the same area is regulated, so that each feeder of the flexible interconnection system in the same area can jointly undertake and collaboratively absorb the grid-connected power of renewable energy.

[0047] Optionally, the cross-regional control module is specifically used for:

[0048] Establish a flexible interconnection system architecture across regions, connecting power distribution feeders in different areas where the distance is greater than a preset distance and the difference between power supply and demand is greater than a threshold.

[0049] Obtain the remaining capacity of the feeder and energy storage systems of the inter-regional flexible interconnection system;

[0050] Based on the feeders of the inter-regional flexible interconnection system and the remaining capacity of the energy storage system, the operation modes of the inter-regional flexible interconnection system are divided.

[0051] Based on the operation mode of the inter-regional flexible interconnection system, corresponding control strategies are adopted to achieve long-distance interconnection between inter-regional low-voltage AC feeders and other regional power grids through energy storage-type flexible soft switches and DC lines.

[0052] Optionally, the operating modes of the flexible interconnection system in the same area include the first operating mode, the second operating mode, the third operating mode, the fourth operating mode, and the fifth operating mode;

[0053] The first operating mode is that all feeders and energy storage systems of the flexible interconnection system in the same area have sufficient spare capacity;

[0054] The second operating mode is that one of the feeders of the flexible interconnection system in the same area has insufficient remaining capacity, while the remaining capacity of the other feeders and the remaining capacity of the energy storage system are sufficient.

[0055] The third operating mode is that the remaining capacity of two feeders in the flexible interconnection system in the same area is insufficient, while the remaining capacity of the other feeders and the remaining capacity of the energy storage system are sufficient; or the remaining capacity of three or more feeders in the flexible interconnection system in the same area is insufficient, but there is at least one feeder with sufficient remaining capacity and the remaining capacity of the energy storage system.

[0056] The fourth operating mode is characterized by insufficient remaining capacity of all feeders in the flexible interconnection system within the same area, while sufficient remaining capacity of the energy storage system.

[0057] The fifth operating mode is when all feeders and energy storage systems in the same area of ​​the flexible interconnection system have insufficient remaining capacity.

[0058] Optionally, the control strategy corresponding to the first operating mode is as follows: one port of the energy storage flexible soft switch adopts a DC voltage-reactive power control strategy to maintain the DC bus voltage stability, while the other ports of the energy storage flexible soft switch and the energy storage system are in standby mode and do not participate in voltage regulation.

[0059] The control strategy corresponding to the second operating mode is as follows: based on the remaining capacity of the feeder of the flexible interconnection system in the same area and the remaining capacity of the energy storage system, the active power-reactive power control strategy and the DC voltage-reactive power control strategy are respectively adopted for each port of the energy storage type flexible soft switch to maintain the stability of the DC bus voltage.

[0060] The control strategy corresponding to the third operating mode is as follows: the two ports of the energy storage type flexible soft switch of the flexible interconnection system in the same area adopt the active power-reactive power control strategy, and the remaining ports adopt the DC voltage-reactive power control strategy to maintain the DC bus voltage stability. The energy storage system does not participate in the regulation.

[0061] The control strategy corresponding to the fourth operating mode is as follows: the two ports of the energy storage type flexible soft switch of the flexible interconnection system in the same area adopt the active power-reactive power control strategy, and the remaining ports adopt the DC voltage-reactive power control strategy to maintain the DC bus voltage stability. The energy storage system is adjusted to the preset power reference value.

[0062] The power control strategy corresponding to the fifth operating mode is as follows: all energy storage systems in the flexible interconnection system in the same area exit voltage regulation and reduce the grid-connected power of distributed power sources on the feeder in preset steps.

[0063] Optionally, the operation modes of the cross-regional flexible interconnection system include the sixth operation mode, the seventh operation mode, the eighth operation mode, the ninth operation mode, and the tenth operation mode;

[0064] The sixth operating mode ensures that all feeders and energy storage systems in the cross-regional flexible interconnection system have sufficient spare capacity;

[0065] The seventh operating mode is that the remaining capacity of the feeder and the remaining capacity of the energy storage system in the local area of ​​the cross-regional flexible interconnection system are sufficient, while the remaining capacity of at least one feeder in the cross-regional system is insufficient.

[0066] The eighth operating mode is that during the process of adjusting the voltage of the feeder node in the cross-regional flexible interconnection system, the voltage of the common connection point of the feeder in this region may exceed the voltage limit.

[0067] The ninth operating mode is that during the process of adjusting the voltage of the feeder nodes in the cross-regional flexible interconnection system, all feeders in this region may experience a risk of voltage exceeding the limit at the common connection point of all feeders in this region.

[0068] The tenth operating mode is characterized by insufficient remaining capacity in all feeders and energy storage systems of the cross-regional flexible interconnection system;

[0069] The operation modes of the cross-regional flexible interconnection system follow a strict priority of judgment. The operation modes are mutually exclusive, and the judgment order from first to last is: sixth operation mode, seventh operation mode, eighth operation mode, ninth operation mode, and tenth operation mode.

[0070] Optionally, the control strategy corresponding to the sixth operating mode is as follows: one energy storage flexible soft switch port in the local area of ​​the cross-regional flexible interconnection system controls the DC voltage to the DC voltage reference value to maintain the DC bus voltage stability, while the other energy storage flexible soft switch ports in the local area and the cross-regional energy storage flexible soft switch ports and the energy storage system are in standby mode and do not participate in voltage regulation.

[0071] The control strategy corresponding to the seventh operating mode is as follows: the cross-regional energy storage flexible soft switch port of the cross-regional flexible interconnection system controls the voltage of the common connection point, one energy storage flexible soft switch port in this region controls the DC bus voltage, and the other energy storage flexible soft switch ports and energy storage system do not participate in voltage regulation;

[0072] The control strategy corresponding to the eighth operating mode is as follows: one port of the local energy storage type flexible soft switch of the cross-regional flexible interconnection system controls the DC voltage as the DC reference voltage and absorbs the excess power of the local feeder and the cross-regional feeder. The other ports of the local energy storage type flexible soft switch of the cross-regional flexible interconnection system switch from controlling the DC voltage to controlling the voltage of the local feeder. The energy storage system of the cross-regional flexible interconnection system does not participate in voltage regulation.

[0073] The control strategy corresponding to the ninth operating mode is as follows: the energy storage system of the cross-regional flexible interconnection system participates in voltage regulation, one port of the local energy storage type flexible soft switch of the cross-regional flexible interconnection system controls the DC voltage as the DC reference voltage and absorbs the excess power on the local feeder, and the other ports of the local energy storage type flexible soft switch switch are switched from controlling the DC voltage to controlling the voltage of the local feeder.

[0074] The control strategy corresponding to the tenth operating mode is as follows: the energy storage system of the inter-regional flexible interconnection system does not participate in voltage regulation, and the grid-connected power of the distributed power source on the feeder of the inter-regional flexible interconnection system is reduced by a preset increment.

[0075] As can be seen from the above technical solutions, the distribution network zonal flexible interconnection and control method based on E-SOP provided by the present invention has the following advantages:

[0076] The present invention provides a distribution network zonal flexible interconnection control method based on E-SOP. It establishes a flexible interconnection system architecture within the same zone, connecting several feeders that are close to a preset distance, have a higher distributed generation penetration rate than a preset rate, higher load density than a preset rate, and exhibit different time characteristics. This method utilizes flexible soft switches connected to the feeder ends and integrating energy storage to regulate the power flow of the same-zone flexible interconnection system. This allows each feeder in the same-zone flexible interconnection system to jointly bear and collaboratively absorb renewable energy grid-connected power, solving the problem of voltage exceeding limits at the feeder ends. Furthermore, it establishes a cross-zone flexible interconnection system architecture, connecting feeders that are far from a preset distance and exhibit power supply and demand differences greater than a threshold. The system interconnects low-voltage AC feeders in different regions with other regional power grids over long distances via energy storage-type flexible soft switches and DC lines. Leveraging the advantages of low line loss and large transmission capacity of DC lines, and through E-SOPs and DC lines, it achieves long-distance interconnection between low-voltage AC feeders in different regions and other regional power grids. This enables wider regional power complementarity and resource sharing, alleviates the problem of power supply and demand imbalance across regions, improves the overall reliability and anti-disturbance capability of the system, and solves the technical problems of power flow reversal, voltage over-limit, and insufficient distributed power absorption capacity caused by large-scale distributed power source access in the same and cross-regional power grids. Attached Figure Description

[0077] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0078] Figure 1 This is a flowchart illustrating a flexible interconnection and control method for distribution network zones based on E-SOP provided in an embodiment of the present invention.

[0079] Figure 2 This is a schematic diagram of a flexible interconnection system architecture based on E-SOP provided in an embodiment of the present invention;

[0080] Figure 3 This is a block diagram of the E-SOP control scheme for flexible interconnection and coordinated regulation in the same region based on E-SOP provided in this embodiment of the invention.

[0081] Figure 4 This is a schematic diagram of a cross-regional flexible interconnection system architecture based on E-SOP provided in an embodiment of the present invention;

[0082] Figure 5 This is a schematic diagram of the three-feeder cross-regional low-voltage flexible interconnection system architecture provided in an embodiment of the present invention;

[0083] Figure 6 This is a block diagram of the VSC and ESS control scheme in the same-area flexible interconnection and collaborative control scheme based on E-SOP provided in the embodiments of the present invention;

[0084] Figure 7 This is a schematic diagram of a three-feeder co-regional low-voltage flexible interconnection system architecture provided in an embodiment of the present invention;

[0085] Figure 8 This is a simulation waveform diagram of the second operating mode in the E-SOP-based flexible interconnection and collaborative control scheme provided in the embodiments of the present invention.

[0086] Figure 9 This is a simulation waveform diagram of the third operating mode in the E-SOP-based flexible interconnection and collaborative control scheme provided in the embodiments of the present invention.

[0087] Figure 10 This is a schematic diagram of the simulation waveform of the fourth operating mode in the E-SOP-based flexible interconnection and collaborative control scheme provided in the embodiments of the present invention.

[0088] Figure 11 This is a simulation waveform diagram of the seventh operating mode in the cross-regional flexible interconnection and collaborative control scheme based on E-SOP provided in the embodiments of the present invention.

[0089] Figure 12 This is a schematic diagram of the simulation waveform of the eighth mode in the cross-regional flexible interconnection and collaborative control scheme based on E-SOP provided in the embodiments of the present invention.

[0090] Figure 13 This is a simulation waveform diagram of the ninth operating mode in the cross-regional flexible interconnection and collaborative control scheme based on E-SOP provided in the embodiments of the present invention.

[0091] Figure 14 This is a schematic diagram of a flexible interconnection and control device for distribution network zones based on E-SOP provided in an embodiment of the present invention. Detailed Implementation

[0092] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0093] Exemplary embodiments will now be described more fully with reference to the accompanying drawings. However, these exemplary embodiments can be implemented in many forms and should not be construed as limited to the embodiments set forth herein; rather, they are provided so that the invention will be thorough and complete, and the concept of the exemplary embodiments will be fully conveyed to those skilled in the art. The same reference numerals in the drawings denote the same or similar parts, and therefore repeated descriptions of them will be omitted.

[0094] The described features, structures, or characteristics can be combined in any suitable manner in one or more embodiments. Numerous specific details are provided in the following description to give a full understanding of embodiments of this disclosure. However, those skilled in the art will recognize that the technical solutions of this disclosure can be practiced without one or more of these specific details, or other methods, components, materials, devices, etc. In these cases, well-known structures, methods, devices, implementations, materials, or operations will not be shown or described in detail.

[0095] Furthermore, the terms “comprising” and “having”, and any variations thereof, are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or apparatus that includes a series of steps or units is not limited to the steps or units listed, but may optionally include steps or units not listed, or may optionally include other steps or units inherent to such process, method, product, or apparatus.

[0096] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0097] For easier understanding, please refer to Figure 1 This invention provides an embodiment of a distribution network zone flexible interconnection control method based on E-SOP, comprising:

[0098] Step 101: Establish a flexible interconnected system architecture within the same area. For several feeders that are close to a preset distance, have a higher distributed power penetration rate than a preset penetration rate, have a higher load density than a preset density, and have different time characteristics, utilize flexible soft switches connected to the end of the feeders and integrating energy storage to regulate the voltage flow of the flexible interconnected system architecture within the same area. This allows each feeder in the flexible interconnected system architecture to jointly bear and collaboratively absorb the grid-connected power of renewable energy. When an AC feeder voltage exceeds the limit in the flexible interconnected system architecture within the same area, a preset flexible interconnected distribution system control strategy is adopted to utilize the remaining capacity of the interconnected feeders and the energy storage system to regulate the voltage of the AC feeder that exceeds the limit.

[0099] It should be noted that the flexible interconnection system architecture based on E-SOP in the same area is as follows: Figure 2 As shown, in the architecture of a flexible interconnected system within the same area, flexible soft switches (SOPs) composed of dual-port or multi-port voltage source converters (VSCs) are connected to multiple low-voltage AC feeders within the same area. These AC feeders contain elements such as distributed generation (DG) and loads, with an energy storage system (ESS) connected to the DC side of the SOP. For several feeders that are close to a preset distance, have a higher DG penetration rate than a preset rate, higher load density than a preset rate, and exhibit different time characteristics, the SOP, connected to the end of the feeder and integrating the ESS, flexibly adjusts the power flow of the flexible interconnected system within the same area. This allows each feeder in the flexible interconnected system to jointly bear and collaboratively absorb the grid-connected power of renewable energy, thus solving the problem of voltage exceeding limits at the feeder ends.

[0100] In one embodiment, for a flexible interconnected system architecture in the same area, several feeders with an electrical distance between feeders close to a preset distance of 500m, a distributed power penetration rate higher than a preset penetration rate of 30%, a load density higher than a preset density of 0.8MW / km, and different time characteristics are identified. The remaining capacity of the feeders and energy storage system of the flexible interconnected system in the same area is obtained. Based on the remaining capacity of the feeders and energy storage system of the flexible interconnected system in the same area, the operating mode of the flexible interconnected system in the same area is divided. According to the operating mode of the flexible interconnected system in the same area, a corresponding control strategy is adopted. Using flexible soft switches connected to the end of the feeders and integrated with energy storage, the voltage of the flexible interconnected system in the same area is regulated, so that each feeder of the flexible interconnected system in the same area can jointly undertake and collaboratively absorb the grid-connected power of renewable energy.

[0101] by Figure 3 Taking the three-feeder co-zone low-voltage flexible interconnection system as an example, when the voltage of a certain AC feeder exceeds the limit, the co-zone flexible interconnection power distribution system control scheme can be adopted to regulate its voltage using the remaining flux of the interconnection feeder and ESS. Figure 3 In the middle, the PCC (Point of Common Coupling) voltage of feeder n As shown in equation (1).

[0102] (1)

[0103] in, Let be the voltage at the beginning of feeder n. The active power transmitted from the network side to the end of the line. The reactive power transmitted from the grid side to the end of the line. Let n be the line resistance of feeder n. Let n be the line reactance of feeder n. The active power of the user load. The reactive power of the user load, The active power output by the distributed power source. The active power transmitted by the voltage source converter connected via feeder n. The reactive power transmitted by the voltage source converter connected via feeder n.

[0104] Differentiating equation (1), when the voltage source converter connected to feeder n... When the active and reactive power are adjusted to meet the line impedance ratio shown in equation (2), the PCC voltage regulation effect of feeder n is optimal.

[0105] (2)

[0106] From equation (1), we can calculate that when VSC does not participate in voltage regulation, i.e. When the feeder node voltage does not exceed the upper limit, the power that the feeder can continue to absorb is called the remaining capacity. To prevent the SOC (State of Charge) from exceeding the upper limit and reducing the ESS's lifespan, the adjustable power of the ESS when it does not exceed the upper limit can be obtained from the SOC. For ease of description, the adjustable power of the ESS is referred to as the remaining capacity in this invention.

[0107] Based on whether the remaining capacity of the feeders and ESS is sufficient (i.e., whether it meets the preset demand for capacity; if it meets the preset demand, the capacity is considered sufficient; if it does not meet the preset demand, the capacity is considered insufficient), the operating modes of the flexible interconnection system in the same area are divided into five modes: Mode 1, Mode 2, Mode 3, Mode 4, and Mode 5. Among them:

[0108] The first operating mode is that all feeders and energy storage systems of the flexible interconnection system in the same area have sufficient spare capacity;

[0109] The second operating mode is that one of the feeders of the flexible interconnection system in the same area has insufficient remaining capacity, while the remaining capacity of the other feeders and the remaining capacity of the energy storage system are sufficient.

[0110] The third operating mode is that the remaining capacity of two feeders in the flexible interconnection system in the same area is insufficient, while the remaining capacity of the other feeders and the remaining capacity of the energy storage system are sufficient; or the remaining capacity of three or more feeders in the flexible interconnection system in the same area is insufficient, but there is at least one feeder with sufficient remaining capacity and the remaining capacity of the energy storage system.

[0111] The fourth operating mode is characterized by insufficient remaining capacity of all feeders in the flexible interconnection system within the same area, while sufficient remaining capacity of the energy storage system.

[0112] The fifth operating mode is when all feeders and energy storage systems in the same area of ​​the flexible interconnection system have insufficient remaining capacity.

[0113] Different control strategies are used to regulate the flexible interconnection system in the same area for different operating modes:

[0114] The control strategy corresponding to the first operating mode is as follows: one port of the energy storage flexible soft switch uses a DC voltage-reactive power control strategy to maintain the DC bus voltage stability, while the remaining ports of the energy storage flexible soft switch and the energy storage system are in standby mode and do not participate in voltage regulation. The control block diagram of the control strategy corresponding to the first operating mode is as follows: Figure 3 As shown, Figure 3 In this context, PI stands for PI controller. This is the reference value for the active power at port k. The output active power of port k, This is the inner loop reference value for the d-axis current at port k. Let d be the d-axis current at port k. This is the reactive power reference value for port k. The output reactive power of port k, This is the inner loop reference value for the q-axis current at port k. Let q be the q-axis current at port k. It is an E-SOP DC bus. This is the reference value for the DC bus voltage of E-SOP. This is the inner loop reference value for the d-axis current at port 3. This represents the d-axis current at port 3. This is the reactive power reference value for port 3. This represents the q-axis current at port 3. This is the inner loop reference value for the q-axis current at port 3. The q-axis current at port 3. This is a reference value for the active power of the energy storage system. The active power of the energy storage system. This is the reference value for the inner current loop of the energy storage system. This refers to the charging and discharging current of the energy storage system. Figure 3In this configuration, E-SOP port 3 employs a DC voltage-reactive power control strategy to maintain stable DC bus voltage, while ports 1, 2, and the ESS are in standby mode and do not participate in voltage regulation. This reduces unnecessary power interaction within the system, minimizes line losses, and extends the ESS's lifespan. Under special circumstances, AC feeders and ESSs that do not participate in voltage regulation can also utilize multi-timescale optimization scheduling methods to predict load and assess the uncertainties of distributed generation, achieving economical system operation.

[0115] The control strategy corresponding to the second operating mode is as follows: based on the remaining capacity of the feeders of the flexible interconnection system in the same area and the remaining capacity of the energy storage system, active power-reactive power control strategy and DC voltage-reactive power control strategy are respectively adopted for each port of the energy storage type flexible soft switch to maintain the stability of the DC bus voltage. Figure 2 Taking the insufficient capacity of feeder 1 as an example, in the second operating mode, E-SOP port 1 adopts an active power-reactive power control strategy, using a combined active and reactive power regulation method to adjust the voltage at the end of feeder 1. Reactive power is compensated locally, while active power is transferred to interconnected feeders 2 and 3. If the remaining capacity of feeders 2 and 3 is insufficient to adjust the voltage of feeder 1 to the normal range, then ESS (Electronic Power Supply) is used to absorb this excess power. When the voltage at the end of feeder 1 exceeds the limit, the active power and reactive power adjustment reference values ​​of E-SOP port 1 can be obtained from equations (1) and (2) as follows:

[0116] (3)

[0117] in, This is the active power adjustment reference value for E-SOP port 1. This is the reference value for reactive power adjustment at port 1 of E-SOP. The node voltage of feeder 1 When the voltage exceeds the upper limit, adjust the node voltage of feeder 1 to the amount of change in node voltage of feeder 1 when the voltage exceeds the upper limit. , This represents the upper limit of the node voltage for feeder 1. For the line resistance of feeder 1, For the line reactance of feeder 1, To adjust the node voltage of feeder 1 using only active power regulation The active power adjusted when the power is adjusted from the upper limit to the upper limit.

[0118] In the second operating mode, if the remaining capacity of feeder 2 and feeder 3 is greater than This indicates that the remaining capacity of feeder 2 and feeder 3 is sufficient to maintain the voltage at the node of feeder 1. Within the normal range, E-SOP ports 2 and 3 jointly regulate the voltage of feeder 1 and allocate the active power of feeder 1 relocation according to the remaining capacity of each feeder. Port 2 adopts an active power-reactive power control strategy, and its active power and reactive power adjustment reference values ​​are:

[0119] (4)

[0120] in, This is the active power adjustment reference value for E-SOP port 2. This is the reference value for reactive power adjustment at port 2 of E-SOP. The node voltage of feeder 2 When the voltage exceeds the upper limit, adjust the node voltage of feeder 2 to the amount of change in node voltage of feeder 2 when the voltage exceeds the upper limit. , This is the upper limit of the node voltage for feeder 2. To adjust the node voltage of feeder 2 using only active power regulation The active power adjusted when the power is adjusted from the upper limit to the upper limit, i.e. This refers to the active power that feeder 2 can absorb while ensuring that the voltage does not exceed the upper limit. The expression is:

[0121] (5)

[0122] in, For regulating the active power of E-SOP port 2, The line resistance of feeder 2 is... This is the voltage at the beginning of the feeder.

[0123] E-SOP port 3 employs a DC voltage-reactive power control strategy to maintain DC bus voltage stability. The outer loop control reference value and its regulated active power for port 3 are as follows:

[0124] (6)

[0125] in, The node voltage of feeder 3 When the voltage exceeds the upper limit, adjust the node voltage of feeder 3 to the amount of change in node voltage of feeder 3 when the voltage exceeds the upper limit. , This represents the upper limit of the node voltage for feeder 3. This is the reference value for adjusting the outer loop voltage at port 3. This is the reference value for reactive power adjustment at port 3. This represents the active power that feeder 3 can absorb while ensuring that the voltage does not exceed the upper limit. The active power is adjusted for port 3 of E-SOP.

[0126] The expression is:

[0127] (7)

[0128] in, For regulating the active power of E-SOP port 3, The line resistance of feeder 3.

[0129] In the second operating mode, if the remaining capacity of feeder 2 and feeder 3 is less than This indicates that the remaining capacity of feeders 2 and 3 is insufficient to reduce the voltage at the node of feeder 1. When adjusted to the normal range, the ESS participates in voltage regulation. At this time, the regulation power reference values ​​of E-SOP port 1, port 2 and ESS are shown in Equation (3), Equation (8) and Equation (10) respectively, and the outer loop reference value and regulation power reference value of port 3 are shown in Equation (9).

[0130] (8)

[0131] (9)

[0132] (10)

[0133] The control strategy corresponding to the third operating mode is as follows: the two ports of the energy storage type flexible soft switch of the flexible interconnection system in the same area adopt the active power-reactive power control strategy, and the remaining ports adopt the DC voltage-reactive power control strategy to maintain the DC bus voltage stability. The energy storage system does not participate in the regulation. Taking the insufficient capacity of feeder 1 and feeder 2 as an example, both ports 1 and 2 adopt the active power-reactive power control strategy, and prioritize the transmission of excess power to feeder 3. Port 3 adopts the DC voltage-reactive power control strategy to maintain the DC bus voltage stability. If the remaining capacity of feeder 3 is sufficient to adjust the node voltage of the other two feeders to the normal range, the power reference values ​​of ports 1 and 2 are shown in Equation (11) and Equation (12) respectively, and the outer loop control reference value of port 3 and its adjusted power reference value are shown in Equation (13). At this time, the ESS does not participate in the regulation.

[0134] (11)

[0135] (12)

[0136] (13)

[0137] in, This is the rated voltage of the DC bus.

[0138] If the remaining capacity of feeder 3 is insufficient to regulate the node voltage of the other two feeders to the normal range, then ESS participates in voltage regulation. The power reference values ​​of port 1 and port 2 remain unchanged. The outer loop reference value of port 3 and its regulated power are shown in equation (9). The power regulation reference value of ESS is shown in equation (14).

[0139] (14)

[0140] When the remaining capacity of three or more feeders in the same area of ​​the flexible interconnection system is insufficient, but at least one feeder has sufficient remaining capacity and the energy storage system has sufficient remaining capacity, the third operating mode control approach is continued. The E-SOP AC port corresponding to the feeder with sufficient remaining capacity is selected as the main power absorption body to accept the excess power of multiple feeders with insufficient capacity; the ports corresponding to multiple feeders with insufficient capacity adopt a combined active and reactive power voltage regulation strategy to prioritize moving excess power to the surplus feeders; the DC port maintains DC bus voltage stabilization, and energy storage is not temporarily put into regulation. When there are no feeders with sufficient remaining capacity, the system switches to the fourth operating mode.

[0141] The control strategy corresponding to the fourth operating mode is as follows: the two ports of the energy storage type flexible soft switch of the flexible interconnection system in the same area adopt the active power-reactive power control strategy, and the remaining ports adopt the DC voltage-reactive power control strategy to maintain the DC bus voltage stability. The energy storage system is adjusted to the preset power reference value. In the fourth operating mode, the control mode and the power reference value of port 1 and port 2 are the same as those of the third operating mode. Port 3 still adopts the DC voltage-reactive power control strategy, but the outer loop reference value and its power adjustment reference value are as shown in Equation (15), and the power adjustment reference value of ESS is as shown in Equation (16).

[0142] (15)

[0143] (16)

[0144] The power control strategy corresponding to the fifth operating mode is as follows: all energy storage systems in the flexible interconnection system in the same area exit voltage regulation and reduce the grid-connected power of distributed power sources on the feeder in preset steps.

[0145] The operating modes of the flexible interconnection system in the same area are divided according to whether the remaining capacity of the feeder and ESS is sufficient, as shown in Table 1. In Table 1, "√" indicates that the remaining capacity is sufficient, and "×" indicates that the remaining capacity is insufficient.

[0146] Table 1

[0147]

[0148] The above-mentioned flexible interconnection and coordinated control scheme in the same area can effectively manage voltage over-limit of power distribution feeders in the same area under various operating modes.

[0149] Step 102: Establish a cross-regional flexible interconnection system architecture. For distribution feeders in different regions that are farther than the preset distance and whose power supply and demand differences are greater than the difference threshold, long-distance interconnection between cross-regional low-voltage AC feeders and other regional power grids is achieved through energy storage-type flexible soft switches and DC lines. When the AC feeder voltage exceeds the limit in the cross-regional flexible interconnection system architecture, the preset cross-regional flexible interconnection distribution system control strategy is adopted to use the remaining capacity of the interconnected feeder and energy storage system to regulate the voltage of the AC feeder that exceeds the limit.

[0150] It should be noted that the cross-regional flexible interconnection system architecture based on E-SOP is as follows: Figure 4 As shown, the cross-regional flexible interconnection system architecture based on E-SOP, building upon the intra-regional flexible interconnection system based on E-SOP, extends the DC side of the VSC at the far-end feeder to a DC bus, enabling power and voltage regulation over a wider area. It is suitable for cross-regional interconnection and mutual support, achieving high-capacity, high-efficiency power transmission through the DC bus. For distribution feeders in different areas with long distances and significant differences in power supply and demand, leveraging the advantages of low line loss and large transmission capacity of DC lines, cross-regional low-voltage AC feeders can be interconnected with other regional power grids over long distances via E-SOP and DC lines. This achieves wider-area power complementarity and resource sharing, alleviating cross-regional power supply and demand imbalances and improving the overall reliability and disturbance rejection capability of the system. Figure 5 Taking the three-feeder cross-regional low-voltage flexible interconnection system as an example, this paper analyzes the operation mode and voltage over-limit management strategy of the cross-regional flexible interconnection system. Figure 5 In the three-feeder cross-regional low-voltage flexible interconnection system shown, feeders 1 and 2 are far from feeder d, and they cannot achieve local communication. However, feeder 2 and the ESS are located in the same area, and they can communicate locally. The cross-regional flexible interconnection system is divided into operating modes based on whether the feeders and ESS have sufficient remaining capacity. The operating modes of the cross-regional flexible interconnection system include the sixth, seventh, eighth, ninth, and tenth operating modes.

[0151] The sixth operating mode ensures that all feeders and energy storage systems in the cross-regional flexible interconnection system have sufficient spare capacity.

[0152] The seventh operating mode is characterized by sufficient remaining capacity of the feeders and energy storage systems within the local area of ​​the inter-regional flexible interconnection system, but insufficient remaining capacity of one feeder across regions. When two or more inter-regional feeders in the inter-regional flexible interconnection system have insufficient remaining capacity, but all feeders and energy storage systems within the local area have sufficient remaining capacity, the control logic of the seventh operating mode is reused: for each inter-regional feeder with insufficient capacity, the voltage at the common coupling point of the inter-regional feeder is adjusted by the E-SOP port corresponding to the surplus feeder in the local area.

[0153] In the eighth operating mode, during the adjustment of the voltage of the feeder node in the cross-regional flexible interconnection system, the voltage of the common connection point of the feeder in this region may exceed the voltage limit.

[0154] The ninth operating mode is that during the process of adjusting the voltage of the feeder nodes in the cross-regional flexible interconnection system, all feeders in this region may experience a risk of voltage exceeding the limit at the common connection point of all feeders in this region.

[0155] The tenth operating mode is characterized by insufficient remaining capacity in all feeders and energy storage systems of the cross-regional flexible interconnection system.

[0156] The different operating modes and their control strategies are as follows:

[0157] The control strategy corresponding to the sixth operating mode is as follows: One energy storage flexible soft-switching port (i.e., a single port within any single E-SOP device in the local area) of the inter-regional flexible interconnection system controls the DC voltage to the DC voltage reference value to maintain DC bus voltage stability. The remaining energy storage flexible soft-switching ports in the local area and the inter-regional energy storage flexible soft-switching ports, as well as the energy storage system, are in standby mode and do not participate in voltage regulation. Only a single voltage regulation control point is allowed for the same DC interconnection bus segment. If all ports of a single E-SOP are used for simultaneous voltage regulation, or if multiple E-SOP ports are used for joint voltage regulation, problems such as DC voltage command conflicts, DC circulating current, and power oscillations will occur. Therefore, only a single port within a single E-SOP is selected as the sole voltage regulation control point. Port 1 controls the DC bus voltage. DC voltage regulation reference value To maintain the stability of the DC bus voltage, the control block diagram is as follows: Figure 6 As shown, Figure 6 middle, For the system's DC bus, This is the reference value for the DC bus voltage. This is the inner loop reference value for the d-axis current at port k. This is the reference value for the inner current loop of the energy storage system. Let d be the d-axis current at port k. For the current of the energy storage system, Let Q be the reactive power reference value for port k, and let Q be the output reactive power of port k. This is the inner loop reference value for the q-axis current at port k. Let q be the q-axis current at port k. This is the reference value for the node voltage at port n. Let n be the node voltage at port n. This is the inner loop reference value for the d-axis current at port n. Let n be the d-axis current. Let n be the line reactance of feeder n. Let n be the line resistance of feeder n. This is the inner loop reference value for the q-axis current at port n. This represents the q-axis current at port n. Ports 2, d, and the ESS are in standby mode and do not participate in voltage regulation to reduce unnecessary power interaction in the system, minimize line loss, and extend the lifespan of the ESS.

[0158] The control strategy corresponding to the seventh operating mode is as follows: The cross-regional energy storage flexible soft-switching port of the cross-regional flexible interconnection system controls the voltage of the point of common coupling (PCC). One energy storage flexible soft-switching port in this region controls the DC bus voltage, while the remaining energy storage flexible soft-switching ports and the energy storage system do not participate in voltage regulation. To alleviate the PCC point voltage over-limit problem of feeder d, port d controls the PCC voltage. Its control block diagram is as follows Figure 6 As shown. Due to the incomplete communication between feeder 1, feeder 2, and feeder d, the power information transmitted by feeder d cannot be directly obtained. Therefore, port 1 still controls... for The excess power of feeder d is absorbed, and port 2 and ESS do not participate in voltage regulation.

[0159] The control strategy corresponding to the eighth operating mode is as follows: One port of the local energy storage flexible soft switch in the inter-regional flexible interconnection system controls the DC voltage to the DC reference voltage and absorbs excess power from the local feeder and the inter-regional feeder. The remaining ports of the local energy storage flexible soft switch in the inter-regional flexible interconnection system switch from controlling the DC voltage to controlling the voltage of the local feeder. The energy storage system of the inter-regional flexible interconnection system does not participate in voltage regulation. During the adjustment of the voltage at node d of feeder 1, a risk of over-limit voltage occurs in the PCC voltage of feeder 1. At this time, feeder 2 participates in voltage regulation, and port 2 controls... for To maintain DC bus voltage stability and absorb excess power from feeder 1 and feeder d, port 1 is controlled by... Switch to control Its control block diagram is as follows Figure 6 As shown, ESS does not participate in voltage regulation.

[0160] The control strategy corresponding to the ninth operating mode is as follows: The energy storage system of the inter-regional flexible interconnection system participates in voltage regulation. One port of the local energy storage flexible soft switch of the inter-regional flexible interconnection system controls the DC voltage as the DC reference voltage and absorbs excess power on the local feeder. The remaining ports of the local energy storage flexible soft switch switch switch switch from controlling the DC voltage to controlling the voltage of the local feeder. During the adjustment of the voltage at node d of feeder 1 and feeder 2, the PCC voltage may exceed the limit. At this time, the ESS participates in voltage regulation and controls... for To maintain DC bus voltage stability and absorb excess power on the feeder, port 2 is controlled by... Switch to control Its control block diagram is as follows Figure 6 As shown.

[0161] The control strategy corresponding to the tenth operating mode is as follows: the energy storage system of the inter-regional flexible interconnection system does not participate in voltage regulation, and the grid-connected power of distributed power sources on the feeders of the inter-regional flexible interconnection system is reduced by a preset increment. In the tenth operating mode, the ESS (Energy Storage System) exits voltage regulation, reduces the grid-connected power of distributed power sources on the feeders, and solves the problem of feeder voltage exceeding limits.

[0162] The operating modes of the cross-regional flexible interconnection system are divided according to whether the remaining capacity of the feeder and ESS is sufficient, as shown in Table 2. In Table 2, "√" indicates that the remaining capacity is sufficient, and "×" indicates that the remaining capacity is insufficient.

[0163] Table 2

[0164]

[0165] The cross-regional flexible interconnection system operates according to a strict priority system, with each mode mutually exclusive. The order of selection, from first to last, is: Mode 6, Mode 7, Mode 8, Mode 9, and Mode 10. The priority determination rule is as follows:

[0166] 1) First, determine whether there is a need to manage overvoltage in the feeder system; if there is no risk of overvoltage in any feeder, directly determine the sixth operating mode, keep all ports in standby, and do not start active voltage regulation;

[0167] 2) If there is a need to address over-limit voltage issues in cross-regional feeders, further assess whether voltage regulation of cross-regional feeders causes PCC over-limit risks in feeders within this region; if voltage regulation does not induce over-limit voltage risks in this region, it should be classified as the seventh operating mode.

[0168] 3) If adjusting the cross-regional feeder voltage induces a risk of voltage over-limit in the feeders in this region, then based on the number of affected local feeders, it will be determined as the eighth operating mode and the ninth operating mode in sequence.

[0169] 4) When all feeders or energy storage systems lose their regulation margin and are unable to complete voltage management, it is determined to be the tenth operating mode.

[0170] The complete implementation path of power interaction in cross-regional flexible interconnection systems relies on the aforementioned E-SOP port control strategy, and the overall principle can be summarized as follows:

[0171] (1) The local E-SOP selects a port according to the operating mode and adopts a DC voltage-reactive power control strategy to stabilize the local DC bus voltage; the cross-regional E-SOP synchronously stabilizes its own DC bus.

[0172] (2) The DC bus on both sides forms a stable voltage reference, and the DC line relies on the bus voltage difference to realize the bidirectional flow of active power;

[0173] (3) The E-SOP AC port corresponding to the surplus feeder in this area outputs / absorbs the regulating power. The power is transmitted to the cross-regional DC bus via the local DC bus and DC line. Finally, the cross-regional E-SOP port acts on the cross-regional feeder to complete the cross-regional power flow mutual assistance and voltage management, and realize the cross-regional flexible interconnection.

[0174] The above-mentioned flexible interconnection and coordinated control scheme in the same area can achieve the suppression of harmonic currents, compensation of unbalanced currents, and management of line voltage exceeding limits in low-voltage distribution networks.

[0175] The present invention provides a distribution network zonal flexible interconnection control method based on E-SOP. It establishes a flexible interconnection system architecture within the same zone, connecting several feeders that are close to a preset distance, have a higher distributed generation penetration rate than a preset rate, higher load density than a preset rate, and exhibit different time characteristics. This method utilizes flexible soft switches connected to the feeder ends and integrating energy storage to regulate the power flow of the same-zone flexible interconnection system. This allows each feeder in the same-zone flexible interconnection system to jointly bear and collaboratively absorb renewable energy grid-connected power, solving the problem of voltage exceeding limits at the feeder ends. Furthermore, it establishes a cross-zone flexible interconnection system architecture, connecting feeders that are far from a preset distance and exhibit power supply and demand differences greater than a threshold. The system interconnects low-voltage AC feeders in different regions with other regional power grids over long distances via energy storage-type flexible soft switches and DC lines. Leveraging the advantages of low line loss and large transmission capacity of DC lines, and through E-SOPs and DC lines, it achieves long-distance interconnection between low-voltage AC feeders in different regions and other regional power grids. This enables wider regional power complementarity and resource sharing, alleviates the problem of power supply and demand imbalance across regions, improves the overall reliability and anti-disturbance capability of the system, and solves the technical problems of power flow reversal, voltage over-limit, and insufficient distributed power absorption capacity caused by large-scale distributed power source access in the same and cross-regional power grids.

[0176] To verify the feasibility and effectiveness of the proposed E-SOP-based flexible interconnection control method for distribution network zones, separate systems were built in Matlab / Simulink. Figure 5 , Figure 7 The simulation model of the three-feed low-voltage flexible interconnection system is shown.

[0177] Figure 7 The schematic diagram of the three-feeder co-regional low-voltage flexible interconnection system architecture provided in this embodiment of the invention, with parameters set in Matlab / Simulink as shown in Table 3.

[0178] Table 3

[0179]

[0180] In the first operating mode, to reduce transmission power loss, the feeders are not interconnected and the system does not perform voltage regulation. In the second, third, and fourth operating modes, the system's ability to absorb distributed power sources is maximized while achieving voltage over-limit. Distributed power sources are controlled at maximum power, and the flexible interconnection system utilizes the remaining capacity of interconnected feeders and ESS for voltage regulation. In the fifth operating mode, each feeder and ESS reaches the upper limit of the distributed power source absorption capacity, and the system limits the grid-connected power of distributed power sources to avoid feeder voltage over-limit.

[0181] The simulated voltage regulation waveforms of the system in the second, third, and fourth operating modes are as follows: Figures 8-10As shown. Figure 8 Figures (a) and (b) show the PCC voltage waveforms of feeders 1, 2, and 3, and the power regulation waveform of the E-SOP device, respectively, under the second operating mode. Figure 8 In the simulation, the timing is as follows: 0~0.2s, the system does not use voltage regulation, the feeders are not interconnected, the regulation power of each port is 0, the voltage of feeder 1 exceeds the limit, and the voltages of feeder 2 and feeder 3 are within the allowable range; 0.2~0.5s, the system adopts the second operating mode voltage regulation strategy, and feeder 2 and feeder 3 absorb the excess power of feeder 1 according to their remaining capacity, thus solving the problem of feeder 1 voltage exceeding the limit.

[0182] Figure 9 Figures (a) and (b) show the PCC voltage waveforms of feeders 1, 2, and 3, and the power regulation waveform of the E-SOP device, respectively, under the third operating mode. Figure 9 In the simulation, the timing is as follows: 0~0.2s, the voltage of feeder 1 and feeder 2 exceeds the limit, while the voltage of feeder 3 is within the allowable range; 0.2~0.5s, the system adopts the third operating mode voltage regulation strategy. Feeder 3 uses its remaining capacity to regulate the excess power of feeder 1 and feeder 2, thus solving the problem of the voltage exceeding the limit of feeder 1 and 2. During this process, the ESS does not participate in voltage regulation, and its regulation power is 0.

[0183] Figure 10 Figures (a) and (b) show the PCC voltage waveforms of feeders 1, 2, and 3, and the power regulation waveform of the E-SOP device, respectively, under the fourth operating mode. Figure 10 In the simulation, the timing is as follows: 0~0.2s, the PCC voltage of feeders 1, 2, and 3 exceeds the limit; 0.2~0.5s, the system adopts the fourth operating mode voltage regulation strategy. The ESS uses its remaining capacity to regulate the excess power of feeders 1, 2, and 3, solves the problem of the voltage exceeding the limit of feeders 1, 2, and 3, and adjusts the PCC voltage of each feeder to the allowable range.

[0184] Figures 8-10 Simulation results show that the E-SOP-based flexible interconnection control method for distribution network zones proposed in this invention can effectively address the problem of feeder voltage exceeding limits in the same distribution network and improve the distribution system's ability to absorb distributed power sources.

[0185] Figure 5 The diagram below shows the architecture of the three-feeder cross-regional low-voltage flexible interconnection system provided in this embodiment of the invention. The parameters set in Matlab / Simulink are shown in Table 4.

[0186] Table 4

[0187]

[0188] Referring to the national standard GB / T 12325-2008 "Power Quality - Supply Voltage Deviation", the upper limit of AC feeder voltage is 1.07 pu. When VSC1, VSC2, and VSCd control the AC side voltage, the reference values ​​for the voltage of the three feeders are as follows: , , Set to 1.043 pu, DC side voltage reference value Set to 1.0 pu.

[0189] In the sixth operating mode, to reduce transmission power loss, the feeders are not interconnected and the system does not perform voltage regulation. In the seventh, eighth, and ninth operating modes, the system's ability to absorb distributed power sources is maximized while achieving voltage over-limit. Distributed power sources are controlled at maximum power, and the flexible interconnection system utilizes the remaining capacity of interconnected feeders and ESS for voltage regulation. In the tenth operating mode, each feeder and ESS reaches the upper limit of the distributed power source absorption capacity, and the system limits the grid-connected power of distributed power sources to avoid feeder voltage over-limit.

[0190] The simulated voltage regulation waveforms of the system in the seventh, eighth, and ninth operating modes are as follows: Figures 11 to 13 As shown.

[0191] Figure 11 Figures (a) and (b) show the PCC voltage waveforms and VSC and ESS regulating power waveforms for feeders 1, 2, and d, respectively, under the seventh operating mode. Figure 10 In the simulation, the timing is as follows: 0~1.8s, the system does not use voltage regulation, the feeders are not interconnected, and the regulation power at each port is 0; 1.8s, the voltage d of the cross-regional feeder. Exceeding limits, port d control for (1.043 pu), the DC voltage controlled by feeder 1 is (1.0 pu), utilizing its remaining capacity for adjustment .

[0192] Figure 12 Figures (a) and (b) show the PCC voltage waveforms and VSC and ESS regulated power waveforms for feeders 1, 2, and d, respectively, under the eighth operating mode. Figure 12 In the simulation, the timing is as follows: 0~1.8s, feeder 1 uses its remaining capacity to adjust the voltage of cross-region feeder d. ; 1.8s, insufficient remaining capacity of feeder 1 caused the PCC voltage of feeder 1 to decrease. When the upper limit is reached, because feeder 1 and feeder 2 are located in the same area, feeder 2 senses the voltage of feeder 1. When the upper limit is reached, port 2 engages voltage regulation to control the DC voltage. (1.0pu), feeder 1 switches to control the PCC voltage of this feeder. ,prevent If the limit is exceeded, the ESS does not participate in voltage regulation during this process, and its regulation power is 0.

[0193] Figure 13 Figures (a) and (b) show the PCC voltage waveforms and VSC and ESS regulated power waveforms for feeders 1, 2, and d, respectively, under the ninth operating mode. Figure 13 In the simulation, the timing is as follows: 0~2.6s, feeder 2 uses its remaining capacity to regulate the PCC voltage of feeder 1 and cross-region feeder d; 2.6s, feeder 2's remaining capacity is insufficient, causing the PCC voltage of feeder 2 to decrease. Upon reaching the upper limit, the ESS senses that the voltage VP2 of feeder 2 has reached the upper limit. The ESS then participates in voltage regulation, controlling the DC voltage to... (1.0 pu), absorb excess power on the feeder, feeder 2 switches to control the PCC voltage of this feeder. ,prevent Exceeding the limit.

[0194] Figures 11 to 13 Simulation results show that the cross-regional flexible interconnection and coordinated control scheme based on E-SOP proposed in this paper can effectively address the problem of cross-regional distribution network feeder voltage exceeding limits and improve the distribution system's ability to absorb distributed generation (DG).

[0195] In summary, the flexible interconnection and control method for distribution network zones based on E-SOP proposed in this invention can effectively solve problems such as power flow backflow, voltage over-limit, and insufficient distributed power absorption capacity caused by large-scale access of distributed power sources in the same or different regions of the power grid.

[0196] For easier understanding, please refer to Figure 14 This invention provides an embodiment of a flexible interconnection and control device for distribution network zones based on E-SOP, comprising:

[0197] The same-area control module is used to establish a flexible interconnected system architecture in the same area. For several feeders that are close to a preset distance, have a higher than preset penetration rate of distributed power sources, higher than preset load density, and have different time characteristics, the module uses energy storage-type flexible soft switches connected to the end of the feeders to regulate the voltage flow of the flexible interconnected system architecture in the same area. This allows each feeder in the flexible interconnected system architecture to jointly bear and collaboratively absorb the grid-connected power of renewable energy. When the AC feeder voltage exceeds the limit in the flexible interconnected system architecture in the same area, the preset flexible interconnected distribution system control strategy in the same area is adopted to regulate the voltage of the AC feeder with the voltage exceeding the limit using the remaining capacity of the interconnected feeders and the energy storage system.

[0198] The cross-regional control module is used to establish a cross-regional flexible interconnection system architecture. For distribution feeders in different regions that are far from the preset distance and whose power supply and demand differences are greater than the difference threshold, long-distance interconnection between cross-regional low-voltage AC feeders and other regional power grids is achieved through energy storage-type flexible soft switches and DC lines. When the AC feeder voltage exceeds the limit in the cross-regional flexible interconnection system architecture, the preset cross-regional flexible interconnection distribution system control strategy is adopted to regulate the voltage of the AC feeder with the voltage exceeding the limit by utilizing the remaining capacity of the interconnected feeder and the energy storage system.

[0199] In one embodiment, the preset control strategy for the flexible interconnected power distribution system in the same area is:

[0200] Obtain the remaining capacity of the feeder and energy storage systems of the flexible interconnection system in the same area;

[0201] Based on the feeders of the flexible interconnection system in the same area and the remaining capacity of the energy storage system, the operation modes of the flexible interconnection system in the same area are divided.

[0202] Based on the operating mode of the flexible interconnection system in the same area, a control strategy corresponding to the operating mode is adopted. By using a flexible soft switch with energy storage integrated at the end of the feeder, the voltage of the flexible interconnection system in the same area is regulated, so that each feeder of the flexible interconnection system in the same area can jointly undertake and collaboratively absorb the grid-connected power of renewable energy.

[0203] In one embodiment, the operating modes of the flexible interconnection system in the same area include a first operating mode, a second operating mode, a third operating mode, a fourth operating mode, and a fifth operating mode;

[0204] The first operating mode is that all feeders and energy storage systems of the flexible interconnection system in the same area have sufficient spare capacity;

[0205] The second operating mode is that one of the feeders of the flexible interconnection system in the same area has insufficient remaining capacity, while the remaining capacity of the other feeders and the remaining capacity of the energy storage system are sufficient.

[0206] The third operating mode is that the remaining capacity of two feeders in the flexible interconnection system in the same area is insufficient, while the remaining capacity of the other feeders and the remaining capacity of the energy storage system are sufficient; or the remaining capacity of three or more feeders in the flexible interconnection system in the same area is insufficient, but there is at least one feeder with sufficient remaining capacity and the remaining capacity of the energy storage system.

[0207] The fourth operating mode is characterized by insufficient remaining capacity of all feeders in the flexible interconnection system within the same area, while sufficient remaining capacity of the energy storage system.

[0208] The fifth operating mode is when all feeders and energy storage systems in the same area of ​​the flexible interconnection system have insufficient remaining capacity.

[0209] In one embodiment, the preset control strategy for the inter-regional flexible interconnection power distribution system is as follows:

[0210] Obtain the remaining capacity of the feeder and energy storage systems of the inter-regional flexible interconnection system;

[0211] Based on the feeders of the inter-regional flexible interconnection system and the remaining capacity of the energy storage system, the operation modes of the inter-regional flexible interconnection system are divided.

[0212] Based on the operation mode of the inter-regional flexible interconnection system, a control strategy corresponding to the operation mode is adopted, and long-distance interconnection between inter-regional low-voltage AC feeders and other regional power grids is carried out through energy storage-type flexible soft switches and DC lines.

[0213] In one embodiment, the control strategy corresponding to the first operating mode is as follows: one port of the energy storage flexible soft switch adopts a DC voltage-reactive power control strategy to maintain the DC bus voltage stability, while the other ports of the energy storage flexible soft switch and the energy storage system are in standby mode and do not participate in voltage regulation.

[0214] The control strategy corresponding to the second operating mode is as follows: based on the remaining capacity of the feeder of the flexible interconnection system in the same area and the remaining capacity of the energy storage system, the active power-reactive power control strategy and the DC voltage-reactive power control strategy are respectively adopted for each port of the energy storage type flexible soft switch to maintain the stability of the DC bus voltage.

[0215] The control strategy corresponding to the third operating mode is as follows: the two ports of the energy storage type flexible soft switch of the flexible interconnection system in the same area adopt the active power-reactive power control strategy, and the remaining ports adopt the DC voltage-reactive power control strategy to maintain the DC bus voltage stability. The energy storage system does not participate in the regulation.

[0216] The control strategy corresponding to the fourth operating mode is as follows: the two ports of the energy storage type flexible soft switch of the flexible interconnection system in the same area adopt the active power-reactive power control strategy, and the remaining ports adopt the DC voltage-reactive power control strategy to maintain the DC bus voltage stability. The energy storage system is adjusted to the preset power reference value.

[0217] The power control strategy corresponding to the fifth operating mode is as follows: all energy storage systems in the flexible interconnection system in the same area exit voltage regulation and reduce the grid-connected power of distributed power sources on the feeder in preset steps.

[0218] In one embodiment, the operating modes of the cross-regional flexible interconnection system include a sixth operating mode, a seventh operating mode, an eighth operating mode, a ninth operating mode, and a tenth operating mode;

[0219] The sixth operating mode ensures that all feeders and energy storage systems in the cross-regional flexible interconnection system have sufficient spare capacity;

[0220] The seventh operating mode is that the remaining capacity of the feeder and the remaining capacity of the energy storage system in the local area of ​​the cross-regional flexible interconnection system are sufficient, while the remaining capacity of at least one feeder in the cross-regional system is insufficient.

[0221] The eighth operating mode is that during the process of adjusting the voltage of the feeder node in the cross-regional flexible interconnection system, the voltage of the common connection point of the feeder in this region may exceed the voltage limit.

[0222] The ninth operating mode is that during the process of adjusting the voltage of the feeder nodes in the cross-regional flexible interconnection system, all feeders in this region may experience a risk of voltage exceeding the limit at the common connection point of all feeders in this region.

[0223] The tenth operating mode is characterized by insufficient remaining capacity in all feeders and energy storage systems of the cross-regional flexible interconnection system;

[0224] The operation modes of the cross-regional flexible interconnection system follow a strict priority of judgment. The operation modes are mutually exclusive, and the judgment order from first to last is: sixth operation mode, seventh operation mode, eighth operation mode, ninth operation mode, and tenth operation mode.

[0225] In one embodiment, the control strategy corresponding to the sixth operating mode is as follows: one energy storage flexible soft switch port in the local area of ​​the cross-regional flexible interconnection system controls the DC voltage to the DC voltage reference value to maintain the DC bus voltage stability, while the other energy storage flexible soft switch ports in the local area and the cross-regional energy storage flexible soft switch ports and the energy storage system are in standby mode and do not participate in voltage regulation.

[0226] The control strategy corresponding to the seventh operating mode is as follows: the cross-regional energy storage flexible soft switch port of the cross-regional flexible interconnection system controls the voltage of the common connection point, one energy storage flexible soft switch port in this region controls the DC bus voltage, and the other energy storage flexible soft switch ports and energy storage system do not participate in voltage regulation;

[0227] The control strategy corresponding to the eighth operating mode is as follows: one port of the local energy storage type flexible soft switch of the cross-regional flexible interconnection system controls the DC voltage as the DC reference voltage and absorbs the excess power of the local feeder and the cross-regional feeder. The other ports of the local energy storage type flexible soft switch of the cross-regional flexible interconnection system switch from controlling the DC voltage to controlling the voltage of the local feeder. The energy storage system of the cross-regional flexible interconnection system does not participate in voltage regulation.

[0228] The control strategy corresponding to the ninth operating mode is as follows: the energy storage system of the cross-regional flexible interconnection system participates in voltage regulation, one port of the local energy storage type flexible soft switch of the cross-regional flexible interconnection system controls the DC voltage as the DC reference voltage and absorbs the excess power on the local feeder, and the other ports of the local energy storage type flexible soft switch switch are switched from controlling the DC voltage to controlling the voltage of the local feeder.

[0229] The control strategy corresponding to the tenth operating mode is as follows: the energy storage system of the inter-regional flexible interconnection system does not participate in voltage regulation, and the grid-connected power of the distributed power source on the feeder of the inter-regional flexible interconnection system is reduced by a preset increment.

[0230] The distribution network zonal flexible interconnection control device based on E-SOP provided in this invention is used to execute the distribution network zonal flexible interconnection control method based on E-SOP provided in this invention. Its principle and the technical effects achieved are the same as those of the distribution network zonal flexible interconnection control method based on E-SOP provided in this invention, and will not be repeated here.

[0231] The terms “first,” “second,” “third,” “fourth,” “fifth,” “sixth,” “seventh,” “eighth,” “ninth,” “tenth,” etc., used in the specification and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that embodiments of the invention described herein can be implemented, for example, in orders other than those illustrated or described herein. Furthermore, the terms “comprising” and “having,” and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0232] In the embodiments provided by this invention, it should be understood that the disclosed systems, apparatuses, and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative; for instance, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be an indirect coupling or communication connection between devices or units through some interfaces, and may be electrical, mechanical, or other forms.

[0233] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0234] Furthermore, the functional units in the various embodiments of the present invention can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit.

[0235] If the integrated unit is implemented as a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art, or all or part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of the present invention. The aforementioned storage medium includes: USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, optical disks, and other media capable of storing program code.

[0236] The above-described embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for flexible interconnection and control of distribution network zones based on E-SOP, characterized in that, include: A flexible interconnected system architecture is established within the same area. For several feeders that are close to a preset distance, have a higher distributed power penetration rate than a preset penetration rate, a higher load density than a preset density, and different time characteristics, the voltage flow of the flexible interconnected system architecture within the same area is regulated by using flexible soft switches connected to the end of the feeders and integrating energy storage. This allows each feeder in the flexible interconnected system architecture to jointly bear and collaboratively absorb the grid-connected power of renewable energy. When the AC feeder voltage exceeds the limit in the flexible interconnected system architecture within the same area, a preset control strategy for the flexible interconnected distribution system within the same area is adopted, using the remaining capacity of the interconnected feeders and the energy storage system to regulate the voltage of the AC feeder that exceeds the limit. A cross-regional flexible interconnection system architecture is established. For distribution feeders in different regions that are far from the preset distance and whose power supply and demand differences are greater than the difference threshold, long-distance interconnection between cross-regional low-voltage AC feeders and other regional power grids is achieved through energy storage-type flexible soft switches and DC lines. When the AC feeder voltage exceeds the limit in the cross-regional flexible interconnection system architecture, the preset cross-regional flexible interconnection distribution system control strategy is adopted to regulate the voltage of the AC feeder with the voltage exceeding the limit by utilizing the remaining capacity of the interconnected feeder and the energy storage system.

2. The method for flexible interconnection and control of distribution network zones based on E-SOP according to claim 1, characterized in that, The preset control strategy for the flexible interconnected power distribution system in the same area is as follows: Obtain the remaining capacity of the feeder and energy storage systems of the flexible interconnection system in the same area; Based on the feeders of the flexible interconnection system in the same area and the remaining capacity of the energy storage system, the operation modes of the flexible interconnection system in the same area are divided. Based on the operating mode of the flexible interconnection system in the same area, a control strategy corresponding to the operating mode is adopted. By using a flexible soft switch with energy storage integrated at the end of the feeder, the voltage of the flexible interconnection system in the same area is regulated, so that each feeder of the flexible interconnection system in the same area can jointly undertake and collaboratively absorb the grid-connected power of renewable energy.

3. The method for flexible interconnection and control of distribution network zones based on E-SOP according to claim 2, characterized in that, The operating modes of the flexible interconnection system in the same area include the first operating mode, the second operating mode, the third operating mode, the fourth operating mode, and the fifth operating mode; The first operating mode is that all feeders and energy storage systems of the flexible interconnection system in the same area have sufficient spare capacity; The second operating mode is that one of the feeders of the flexible interconnection system in the same area has insufficient remaining capacity, while the remaining capacity of the other feeders and the remaining capacity of the energy storage system are sufficient. The third operating mode is that the remaining capacity of two feeders in the flexible interconnection system in the same area is insufficient, while the remaining capacity of the other feeders and the remaining capacity of the energy storage system are sufficient; or the remaining capacity of three or more feeders in the flexible interconnection system in the same area is insufficient, but there is at least one feeder with sufficient remaining capacity and the remaining capacity of the energy storage system. The fourth operating mode is characterized by insufficient remaining capacity of all feeders in the flexible interconnection system within the same area, while sufficient remaining capacity of the energy storage system. The fifth operating mode is when all feeders and energy storage systems in the same area of ​​the flexible interconnection system have insufficient remaining capacity.

4. The method for flexible interconnection and control of distribution network zones based on E-SOP according to claim 1, characterized in that, The preset control strategy for the inter-regional flexible interconnection power distribution system is as follows: Obtain the remaining capacity of the feeder and energy storage systems of the inter-regional flexible interconnection system; Based on the feeders of the inter-regional flexible interconnection system and the remaining capacity of the energy storage system, the operation modes of the inter-regional flexible interconnection system are divided. Based on the operation mode of the inter-regional flexible interconnection system, a control strategy corresponding to the operation mode is adopted, and long-distance interconnection between inter-regional low-voltage AC feeders and other regional power grids is carried out through energy storage-type flexible soft switches and DC lines.

5. The distribution network zone flexible interconnection and control method based on E-SOP according to claim 4, characterized in that, The operation modes of the cross-regional flexible interconnection system include the sixth operation mode, the seventh operation mode, the eighth operation mode, the ninth operation mode, and the tenth operation mode; The sixth operating mode ensures that all feeders and energy storage systems in the cross-regional flexible interconnection system have sufficient spare capacity; The seventh operating mode is that the remaining capacity of the feeder and the remaining capacity of the energy storage system in the local area of ​​the cross-regional flexible interconnection system are sufficient, while the remaining capacity of at least one feeder in the cross-regional system is insufficient. The eighth operating mode is that during the process of adjusting the voltage of the feeder node in the cross-regional flexible interconnection system, the voltage of the common connection point of the feeder in this region may exceed the voltage limit. The ninth operating mode is that during the process of adjusting the voltage of the feeder nodes in the cross-regional flexible interconnection system, all feeders in this region may experience a risk of voltage exceeding the limit at the common connection point of all feeders in this region. The tenth operating mode is characterized by insufficient remaining capacity in all feeders and energy storage systems of the cross-regional flexible interconnection system; The operation modes of the cross-regional flexible interconnection system follow a strict priority of judgment. The operation modes are mutually exclusive, and the judgment order from first to last is: sixth operation mode, seventh operation mode, eighth operation mode, ninth operation mode, and tenth operation mode.

6. The distribution network zone flexible interconnection and control method based on E-SOP according to claim 3, characterized in that, The control strategy corresponding to the first operating mode is as follows: one port of the energy storage flexible soft switch adopts the DC voltage-reactive power control strategy to maintain the DC bus voltage stability, while the other ports of the energy storage flexible soft switch and the energy storage system are in standby mode and do not participate in voltage regulation. The control strategy corresponding to the second operating mode is as follows: based on the remaining capacity of the feeder of the flexible interconnection system in the same area and the remaining capacity of the energy storage system, the active power-reactive power control strategy and the DC voltage-reactive power control strategy are respectively adopted for each port of the energy storage type flexible soft switch to maintain the stability of the DC bus voltage. The control strategy corresponding to the third operating mode is as follows: the two ports of the energy storage type flexible soft switch of the flexible interconnection system in the same area adopt the active power-reactive power control strategy, and the remaining ports adopt the DC voltage-reactive power control strategy to maintain the DC bus voltage stability. The energy storage system does not participate in the regulation. The control strategy corresponding to the fourth operating mode is as follows: the two ports of the energy storage type flexible soft switch of the flexible interconnection system in the same area adopt the active power-reactive power control strategy, and the remaining ports adopt the DC voltage-reactive power control strategy to maintain the DC bus voltage stability. The energy storage system is adjusted to the preset power reference value. The power control strategy corresponding to the fifth operating mode is as follows: all energy storage systems in the flexible interconnection system in the same area exit voltage regulation and reduce the grid-connected power of distributed power sources on the feeder in preset steps.

7. The method for flexible interconnection and control of distribution network zones based on E-SOP according to claim 5, characterized in that, The control strategy corresponding to the sixth operating mode is as follows: In the cross-regional flexible interconnection system, one energy storage type flexible soft switch port in this region controls the DC voltage to the DC voltage reference value to maintain the stability of the DC bus voltage. The other energy storage type flexible soft switch ports in this region and the cross-regional energy storage type flexible soft switch ports, as well as the energy storage system, are in standby mode and do not participate in voltage regulation. The control strategy corresponding to the seventh operating mode is as follows: the cross-regional energy storage flexible soft switch port of the cross-regional flexible interconnection system controls the voltage of the common connection point, one energy storage flexible soft switch port in this region controls the DC bus voltage, and the other energy storage flexible soft switch ports and energy storage system do not participate in voltage regulation; The control strategy corresponding to the eighth operating mode is as follows: one port of the local energy storage type flexible soft switch of the cross-regional flexible interconnection system controls the DC voltage as the DC reference voltage and absorbs the excess power of the local feeder and the cross-regional feeder. The other ports of the local energy storage type flexible soft switch of the cross-regional flexible interconnection system switch from controlling the DC voltage to controlling the voltage of the local feeder. The energy storage system of the cross-regional flexible interconnection system does not participate in voltage regulation. The control strategy corresponding to the ninth operating mode is as follows: the energy storage system of the cross-regional flexible interconnection system participates in voltage regulation, one port of the local energy storage type flexible soft switch of the cross-regional flexible interconnection system controls the DC voltage as the DC reference voltage and absorbs the excess power on the local feeder, and the other ports of the local energy storage type flexible soft switch switch are switched from controlling the DC voltage to controlling the voltage of the local feeder. The control strategy corresponding to the tenth operating mode is as follows: the energy storage system of the inter-regional flexible interconnection system does not participate in voltage regulation, and the grid-connected power of the distributed power source on the feeder of the inter-regional flexible interconnection system is reduced by a preset increment.

8. A flexible interconnection and control device for distribution network zones based on E-SOP, characterized in that, include: The same-area control module is used to establish the same-area flexible interconnection system architecture. It connects several feeders that are close to the preset distance, have a higher than the preset penetration rate of distributed power sources, have a higher than the preset load density, and have different time characteristics. It uses energy storage-type flexible soft switches connected to the end of the feeders to regulate the power flow of the same-area flexible interconnection system, so that each feeder of the same-area flexible interconnection system can jointly bear and collaboratively absorb the grid-connected power of renewable energy. The cross-regional control module is used to establish a cross-regional flexible interconnection system architecture. It connects power distribution feeders in different regions that are far apart from a preset distance and whose power supply and demand differences are greater than the difference threshold, through energy storage-type flexible soft switches and DC lines, to achieve long-distance interconnection between cross-regional low-voltage AC feeders and other regional power grids.

9. The distribution network zone flexible interconnection and control device based on E-SOP according to claim 8, characterized in that, The same-area control module is specifically used for: Establish a flexible interconnection system architecture in the same area, connecting several feeders that are close to the preset distance, have a higher than the preset penetration rate of distributed power sources, have a higher than the preset load density, and have different time characteristics; Obtain the remaining capacity of the feeder and energy storage systems of the flexible interconnection system in the same area; Based on the feeders of the flexible interconnection system in the same area and the remaining capacity of the energy storage system, the operation modes of the flexible interconnection system in the same area are divided. Based on the operating mode of the flexible interconnection system in the same area, a corresponding control strategy is adopted. By using a flexible soft switch with energy storage integrated at the end of the feeder, the voltage of the flexible interconnection system in the same area is regulated, so that each feeder of the flexible interconnection system in the same area can jointly undertake and collaboratively absorb the grid-connected power of renewable energy.

10. The distribution network zone flexible interconnection and control device based on E-SOP according to claim 8, characterized in that, The cross-regional control module is specifically used for: Establish a flexible interconnection system architecture across regions, connecting power distribution feeders in different areas where the distance is greater than a preset distance and the difference between power supply and demand is greater than a threshold. Obtain the remaining capacity of the feeder and energy storage systems of the inter-regional flexible interconnection system; Based on the feeders of the inter-regional flexible interconnection system and the remaining capacity of the energy storage system, the operation modes of the inter-regional flexible interconnection system are divided. Based on the operation mode of the inter-regional flexible interconnection system, corresponding control strategies are adopted to achieve long-distance interconnection between inter-regional low-voltage AC feeders and other regional power grids through energy storage-type flexible soft switches and DC lines.

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