Plug-and-play distribution network system, networking method and access point selection method

Abstract

A plug-and-play distribution network system, a networking method and an access point selection method. The distribution network system includes a distribution network automation master station, a fusion terminal, a plurality of primary devices and a plurality of secondary devices. The high-speed carrier cco communication module and the STA module are connected by a carrier signal, enabling the system to determine the online / offline status of each distribution device and calculate the optimized access point conditions for distributed power sources in the distribution network. The fusion terminal is signal-connected to each primary device and secondary device in the distribution network, communicates regularly, and establishes a mapping between primary and secondary devices. Whether a distribution device is a newly added device is determined by whether the mapping can be established to continuously monitor the online / offline status of nodes. This design can not only determine the online / offline status and optimized access point conditions of each distribution device through carrier signals to realize the automatic networking of the distribution network, but also be applicable to various controllable resources in the distribution network, effectively expanding the applicable scope of the networking method.

Description

Technical Field

[0001] The present invention relates to a distribution network system, and more particularly to a plug-and-play distribution network system, a networking method, and an access point selection method. Background Art

[0002] To adapt to the large-scale access of distributed power sources and improve the acceptance capacity of the distribution network, it is necessary to increase the transmission capacity of the distribution network, which will result in a significant reduction in the operating efficiency of the distribution network. In addition, with the in-depth development of electric energy substitution, the penetration rate of electric vehicles continues to increase. New emerging clean energy supply stations, user-side demand response loads, directly controlled loads, etc. have put forward new requirements for the power supply reliability of the distribution network. However, due to the different application scenarios and working principles of various loads, there is no clear standard for the requirements of the distribution network. The existing low-voltage distribution network planning methods do not adequately consider emerging loads and are prone to becoming the main factors restricting the development of new loads, which is not conducive to the construction and development of the new power system. Currently, the load response mechanism is still unclear, the uncertainty on the power supply side is becoming increasingly prominent, the distribution of source-load resources at the substation level is uneven, and the weakness of distribution facilities seriously restricts the high-quality development of the low-voltage distribution network in the direction of carbon-electricity coordination.

[0003] The "plug-and-play" of intelligent devices means that when a new device is physically connected to the power grid, the grid management platform can automatically identify the newly connected device and manage and control the device. To accurately serve the energy consumption needs of various typical regions, improve the new energy consumption capacity and the integrated operation level of the source-network-load-storage, and contribute to the construction of the new power system, it is urgent to conduct research on the architecture system of the "plug-and-play" energy flow and information flow levels of the distribution network, propose a "plug-and-play" implementation solution based on HPLC technology for adapting to flexible resources, realize two-way communication and intelligent control between power equipment and power consumption terminals, promote the optimization and upgrading of the low-voltage distribution network, guide the construction and access of low-voltage distributed photovoltaics, energy storage, and electric vehicles, and contribute to the intelligent upgrading of the power grid.

[0004] Although these methods can all achieve the plug-and-play of some controllable resources in the distribution network, they still have the following defects:

[0005] 1. The existing plug-and-play methods for controllable resources in the distribution network cannot be applied to all types of controllable resources in the distribution network due to the lack of standardization of the distribution terminals in the current distribution substations and the lack of a unified model for the plug-and-play function, resulting in a small scope of application.

[0006] 2. The existing plug-and-play methods for controllable resources in the distribution network cannot obtain the optimal access point positions of the controllable resources, and a large number of maintenance personnel are required for on-site communication debugging after installation, increasing the operating cost of the distribution network.

[0007] Disclosing the information of this background art section is only intended to enhance the overall understanding of the background of this application, and should not be construed as an admission or any form of implication that this information constitutes prior art already known to those of ordinary skill in the art. Summary of the Invention

[0008] The object of the present invention is to overcome the disadvantages of a relatively small scope of application and a relatively high operating cost of the distribution network in the prior art, and to provide a plug-and-play distribution network system, a networking method and an access point selection method with a relatively large scope of application and a relatively low operating cost of the distribution network.

[0009] To achieve the above object, the technical solution of the present invention is as follows:

[0010] A plug-and-play distribution network system, the distribution network system includes: a distribution network automation master station, a fusion terminal, a plurality of primary devices and a plurality of secondary devices;

[0011] A high-speed carrier cco communication module is provided on the fusion terminal, and the fusion terminal is signal-connected to the high-speed carrier cco communication module provided thereon.

[0012] Each of the primary devices and secondary devices is provided with a STA module, and each of the primary devices and secondary devices is signal-connected to the STA module provided thereon;

[0013] The distribution network automation master station is signal-connected to the fusion terminal, the fusion terminal is signal-connected to the high-speed carrier cco communication module, and the high-speed carrier cco communication module is simultaneously signal-connected to all STA modules in the distribution network;

[0014] The distribution network automation master station is used for ledger confirmation and file distribution, the fusion terminal is used for setting access rules and identifying characteristic currents, and the high-speed carrier cco communication module and the STA module are used to implement high-speed carrier communication in the distribution network;

[0015] The fusion terminal is used to automatically identify newly connected secondary devices in the distribution network and manage and control the secondary devices.

[0016] The fusion terminal is also used to select the optimal access point position of secondary devices in the distribution network.

[0017] A networking method for a plug-and-play distribution network system, characterized in that:

[0018] The networking method includes the following steps:

[0019] S1. Device registration. The fusion terminal sends registration information to the distribution network automation master station. When the distribution network automation master station receives the registration information, it proceeds to S2;

[0020] S2. Send the device description file. After the distribution network automation master station receives the registration information, it sends the next device description file of the substation area to the integrated terminal. When the integrated terminal receives the next device description file of the substation area, it proceeds to S3;

[0021] S3. Device description file parsing. The integrated terminal parses the received next device description file of the substation area to obtain the PMS_ID. After the integrated terminal obtains the PMS_ID, it sends the PMS_ID to each secondary device in the distribution network. When the secondary device receives the PMS_ID, it proceeds to S4;

[0022] S4. Device mapping. After each primary device and secondary device in the distribution network receives the PMS_ID, the STA module on the primary device and secondary device sends feedback information to the integrated terminal through the carrier signal. After the integrated terminal receives the feedback information, it performs registration discovery on the newly connected secondary devices and proceeds to S5;

[0023] S5. Establish device mapping. The communication module of the integrated terminal performs primary-secondary device mapping on all secondary devices respectively, generates an intelligent electronic device capability description file based on the mapping results of the primary-secondary devices, and instantiates the intelligent electronic device capability description file at the same time. When the instantiation of the intelligent electronic device capability description file is completed, it proceeds to S6;

[0024] S6. The communication module of the integrated terminal communicates normally with the secondary device and transmits the IED instance configuration file of this type of device generated by the communication module to the integrated terminal. The integrated terminal forms the total IED instance configuration file of the substation area and uploads it to the distribution network automation master station. The total IED instance configuration file of the substation area contains all the data points in the substation area and the data points default to be uploaded to the master station. When the distribution network automation master station receives the total IED instance configuration file of the substation area, it proceeds to S7;

[0025] S7. Generate the CID file. The distribution network automation master station receives the IED instance configuration file uploaded by the integrated terminal, parses the IED instance configuration file uploaded by the integrated terminal, establishes a communication model on the master station side according to the parsing result, and automatically completes the subscription to the data set, generating the CID file. The data set includes the operation data of the distribution transformer corresponding to the substation area of the integrated terminal, the device conditions and operation data of each primary device connected to the low-voltage power grid.

[0026] The device mapping in S4 includes the following steps:

[0027] After each primary device and secondary device in the distribution network receives the PMS_ID, the STA module on the primary device and secondary device sends feedback information to the integrated terminal through the carrier signal. After the integrated terminal receives the feedback information, it performs registration discovery on the newly connected secondary devices and proceeds to S5.

[0028] The mapping of the S4 device includes the following steps:

[0029] When a newly added secondary device is installed in the distribution network, the secondary device sends a request message to the high-speed carrier cco communication module set on the fusion terminal through the STA module set on it. The request message includes that when the fusion terminal receives the request message, it sends the registration communication address, device type, and the corresponding primary device PMS_ID to the secondary device that sent the request message through the high-speed carrier cco communication module.

[0030] The networking method further includes the following steps:

[0031] S8. Identify the node access location and line. The distribution network automation master station sends the CID file with the dataset set to the fusion terminal. The fusion terminal parses the received CID file, generates a communication model for the information interaction between the fusion terminal and the distribution network automation master station according to the parsing result, and conducts information interaction with the master station through the standard protocol.

[0032] The communication model on the master station side includes a master station layer, a regional layer, and a local layer. The master station layer is the distribution network automation master station, the regional layer is the fusion terminal, and the local layer is the secondary device. The master station layer, the regional layer, and the local layer jointly form a three-level communication architecture through their corresponding high-speed carrier cco communication modules and STA modules.

[0033] The S8 for identifying the node access location and line includes the following steps:

[0034] Collect the voltage U of each transformer in the distribution network a and the voltage u b ′ of each terminal device. Perform dimensionless processing on the voltage information U a and u b ′ to obtain the normalized value U a ′ of the low-voltage side voltage of transformer a and the normalized value U″ of the access point voltage of dimensionless terminal device b b , and the expressions of U a ′ and u″ b are:

[0035]

[0036]

[0037] In the above formula, t is the t-th acquisition point of the voltage data, and 1 represents the first voltage data acquisition point in the distribution network;

[0038] Calculate the voltage fluctuation similarity coefficient θ ab (t) of the terminal device and the transformer. The expression of the voltage fluctuation similarity coefficient θ ab (t) is:

[0039]

[0040] In the above formula, Δu ab (t) = |u″ b (t) - U′ a (t)|, σ is the resolution coefficient, min a min b Δu ab (t) is the value of Δu ab (t) corresponding to the minimum voltage on the low - voltage side of the t - th transformer, that is, the minimum tap ratio; max a max b Δu ab (t) is the value of Δu ab (t) corresponding to the maximum voltage on the low - voltage side of the t - th transformer, that is, the maximum tap ratio;

[0041] Calculate the voltage fluctuation correlation degree between the terminal device and the transformer The said voltage fluctuation correlation degree The expression is:

[0042]

[0043] Any terminal device belongs to the transformer sub - station where the transformer with the highest correlation degree is located.

[0044] The said S5 establishing device mapping includes the following steps:

[0045] After the fusion terminal receives the feedback information, it establishes the primary - secondary device mapping for all secondary devices. If the PMS_ID information of the secondary device can be found in the primary device PMS_ID list, the primary - secondary device mapping of this secondary device is successfully established. If the PMS_ID information of any secondary device cannot be found in the primary device PMS_ID list, the primary - secondary device mapping of this secondary device fails. After all secondary devices have been mapped, the fusion terminal generates a list of secondary devices with successful mapping and a list of secondary devices with failed mapping according to the mapping results, and generates a smart electronic device capability description file according to the mapping results, and instantiates the smart electronic device capability description file at the same time. After the instantiation of the smart electronic device capability description file is completed, it enters S6.

[0046] A method for selecting an access point of a plug - and - play distribution network system, characterized in that:

[0047] When the distribution network system needs to newly access secondary devices, the fusion terminal runs the access point selection method;

[0048] The said access point selection method includes the following steps:

[0049] First step, establish a distributed power optimization access point model. The distributed power optimization access point model includes the node power flow balance condition under critical conditions, the reactive power limit condition under critical conditions, the power reverse flow limit condition under critical conditions, the voltage deviation limit condition under critical conditions, and the line capacity limit condition under critical conditions. Define the total number of nodes in the distributed power optimization access point model as N, and sort them from 1 to N. Let the node where the distributed power is connected during the calculation of the distributed power optimization access point model be node i, and the j-th node among the N nodes of the distributed power optimization access point model be node j. The node power flow balance condition under critical conditions includes the active power and reactive power injected by node i. The expression for the active power injected by the node is:

[0050]

[0051] The expression for the reactive power injected by the node is:

[0052]

[0053] In the above formula, P s,i is the active power injected by node i, Q s,i is the reactive power injected by node i, U i is the voltage amplitude of node i, U j is the voltage amplitude of node j, G i,j is the real part of the system admittance matrix, B i,j is the imaginary part of the system admittance matrix, θ i,j is the voltage phase angle difference between node i and j;

[0054] The expression for the reactive power limit condition under critical conditions is:

[0055]

[0056] The S DGk is the capacity of the distributed power connected at the voltage data acquisition point k, P DGk is the active power generated by the distributed power at the voltage data acquisition point k, Q DGk is the reactive power generated by the distributed power at the voltage data acquisition point k;

[0057] The expression for the power reverse flow limit condition under critical conditions is:

[0058] η DG，t P DGk，max ≤η Load ,P Load，max +βR Load，max ;

[0059] In the above formula, PDGk,max is the maximum output power of the distributed power source, P Load,max is the maximum load of the distributed power source, η DG,t is the ratio of the active power output of the distributed power source at time t to its maximum output, η load,t is the ratio of the load at time t to the maximum load of the network, β is the power flow reverse coefficient, and when β = 0, reverse power flow at the head end is not allowed;

[0060] The expression for the voltage deviation limit condition under the critical condition is:

[0061] ΔU% min ≤(U i -U e ) / U e ≤ΔU% max ;

[0062] In the above formula, U e is the rated voltage, ΔU% min is the upper limit of the voltage deviation, ΔU% max is the lower limit of the voltage deviation;

[0063] The expression for the line capacity limit condition under the critical condition is:

[0064] S Lm ≤S Lm，max ;

[0065] S Lm is the apparent power of line m at present, S Lm,max is the maximum allowable capacity of line m;

[0066] In the second step, simplify the optimized access point model of the distributed power source. By replacing the leading power factor in the distributed power source with the lagging power factor, the expression for the reactive power injected at the node after simplification is:

[0067]

[0068] In the above formula is the maximum lagging power factor during the operation of the distributed power source;

[0069] Take the moment corresponding to the minimum load and the maximum output of the distributed power source in the prediction curve as the critical condition of the power flow reverse limit condition, and the expression for the power flow reverse limit condition under the simplified critical condition is:

[0070]

[0071] By selecting nodes, the branch load is equivalent to the connection point, simplifying the tree-like topological structure to a single-radiation topology. During the calculation of the voltage drop, the influence of the transverse component is ignored, and at the same time, it is assumed that the denominator of the longitudinal component of the voltage drop is the rated voltage Ue , the approximate expression of the voltage deviation at the grid connection point k is obtained:

[0072]

[0073] In the above formula, ΔU k % is the voltage deviation at the voltage data acquisition point k, N is the total number of nodes, and P L,k is the maximum active load of node k, and Q L,k is the maximum reactive load of the voltage data acquisition point k;

[0074] In the third step, calculate the functional relationship between the maximum access power of the distributed power source and the voltage deviation. Substitute the simplified reactive power expression injected into the node into the approximate expression of the voltage deviation at the grid connection point k, and the expression of the functional relationship between the maximum access power of the distributed power source and the voltage deviation is obtained as:

[0075]

[0076] In the above formula, P DGk,max(V) is the estimated value of the plug-and-play critical condition of the distributed power source. α is the loss correction coefficient, which is used to compensate for the underestimated value caused by ignoring the losses in the network. The loss correction coefficient α is equal to the ratio of the total power supply to the total power consumption in the network before the distributed power source is connected;

[0077] In the fourth step, calculate the power flow flowing through each node after the distributed power source is connected to the grid. Assume that the capacity of each section of the line is S L , ignoring the losses in the network, the approximate expression of the power flow flowing through each node after the distributed power source is connected to the grid is;

[0078]

[0079] In the above formula, is the approximate value of the node power corresponding to the end node of the line model, is the approximate value of the node power corresponding to the node adjacent to the end node in the line model, is the approximate value of the node power corresponding to the node adjacent to the end node in the direction of the voltage data acquisition point k in the line model, is the approximate value of the node power corresponding to the voltage data acquisition point k in the line model, is the approximate value of the node power corresponding to the starting node of the line model;

[0080] In the fifth step, simplify the line capacity constraint. Only consider that the power flow at the access point k does not exceed the allowable line capacity, and the expression of the simplified line capacity constraint is obtained as:

[0081]

[0082] In the above formula, is the estimated value of the plug-and-play critical condition of the distributed power source, and S L is the line capacity, is the minimum power factor allowed for the line;

[0083] Step 6: Obtain the access point location. By solving the optimized access point model of the distributed power source, the optimal power corresponding to the nearest access point for the device to be connected is obtained. The expression of the optimal power is:

[0084]

[0085] In the above formula, maxP DG is the optimal power corresponding to the nearest access point for the device to be connected. Comparing the maximum output of the distributed power source and the optimal power corresponding to the nearest access point, when the optimal power corresponding to the nearest access point is greater than the maximum output of the distributed power source, this nearest access point is the optimal access location;

[0086] If the optimal power corresponding to the nearest access point is less than the maximum output of the distributed power source, then the access points on both sides of this nearest access point are selected for optimal power calculation until the optimal power corresponding to the selected access point is greater than the maximum output of the distributed power source.

[0087] Compared with the prior art, the beneficial effects of the present invention are:

[0088] 1. In the plug-and-play distribution network system of the present invention, the signals of the high-speed carrier cco communication module and the STA module can be connected through the carrier signal, so that the system can determine the online / offline status of each distribution device and calculate the optimized access point conditions of the distributed power source in the distribution network. Therefore, this design can determine the online / offline status and optimized access point conditions of each distribution device through the carrier signal, and realize the automatic networking of the distribution network.

[0089] 2. In the networking method of the plug-and-play distribution network system of the present invention, the fusion terminal is connected to the signals of each primary device and secondary device in the distribution network through the high-speed carrier cco communication module. By communicating regularly and establishing a mapping between the primary and secondary devices, it is determined whether the distribution device is a newly added device by whether the mapping between the primary and secondary devices can be established, achieving the effect of continuously monitoring the online / offline status of the nodes, and there is no need to standardize the controllable resources such as distribution terminals. Therefore, this design can be applied to various controllable resources in the distribution network and effectively expand the applicable range of the networking method.

[0090] 3. In the networking method of the plug-and-play distribution network system of the present invention, the topological relationship between the intelligent terminal in the edge-side substation area and the end devices such as the underlying intelligent electricity meters is automatically checked and maintained in a polling manner. The location of the end devices is identified by the pulse voltage fluctuation law with strong similarity among users powered by the same substation area and the same phase. Therefore, this design can fully automatically complete the online / offline status monitoring of distribution equipment and identify the location of newly connected distribution equipment, effectively improving the automation level of the system.

[0091] 4. In the access point selection method of the plug-and-play distribution network system of the present invention, a distributed power source optimal access point model is established through the node power flow balance condition under critical conditions, the reactive power limitation condition under critical conditions, the power reverse transmission limitation condition under critical conditions, the voltage deviation limitation condition under critical conditions, and the line capacity limitation condition under critical conditions. Then, the model is simplified and solved to obtain the optimal power of the access point and the optimal access point location of the controllable resources. Therefore, this design can obtain the optimal access point location of the controllable resources through the distributed power source optimal access point model, effectively reducing the operation cost of the distribution network. BRIEF DESCRIPTION OF THE DRAWINGS

[0092] Figure 1 It is a schematic structural diagram of the present invention.

[0093] Figure 2 It is a plug-and-play structure diagram of the distribution network of the present invention.

[0094] Figure 3 It is a key technology diagram of HPLC in the present invention.

[0095] Figure 4 It is a plug-and-play flow chart of the fusion terminal in the present invention.

[0096] Figure 5 It is a simplified schematic diagram of the tree-like topological structure in the present invention.

[0097] In the figure: the distribution network automation master station 1, the fusion terminal 2, the high-speed carrier cco communication module 21, the primary equipment 3, the secondary equipment 4, and the STA module 5. DETAILED DESCRIPTION OF THE INVENTION

[0098] The present invention will be further described in detail below in conjunction with the accompanying drawings and the detailed implementation manners.

[0099] The principle of the present invention is described as follows:

[0100] The distribution network networking method in the present invention runs in real time during the operation of the distribution network to monitor the online / offline status of each secondary equipment 4 in the distribution network in real time, and at the same time confirm whether each secondary equipment 4 is a newly added device;

[0101] The feedback information is that the signal corresponding to the PMS_ID has been confirmed to be received, and the discrimination coefficient σ takes a value of 0.5;

[0102] In the present invention, the primary equipment 3 is a high-voltage electrical equipment directly used in the production process of generating, transmitting, and distributing electric energy, including generators, transformers, circuit breakers, disconnectors, automatic switches, contactors, knife switches, busbars, transmission lines, power cables, reactors, motors, etc.; the secondary equipment 4 is a low-voltage electrical equipment required for monitoring, controlling, regulating, protecting the operation of the primary equipment 3 and providing operating conditions or production command signals for operators and maintenance personnel, including fuses, buttons, indicator lights, control switches, relays, control cables, instruments, signal devices, automatic devices, etc.;

[0103] See Figure 3 , after the power grid in this design is powered on, the high-speed carrier cco communication module 21 sends a central beacon. After the sub-node STA module 5 receives the beacon, the STA module 5 makes an association request, and the high-speed carrier cco communication module 21 makes an association confirmation or rejects network access;

[0104] This design adopts a distributed routing. The sub-nodes in the network participate in decision-making for their respective paths and dynamically update according to the power line environment;

[0105] This design also has an inter-network coordination mechanism and a concurrent meter reading mechanism. The inter-network coordination mechanism is for an environment where multiple networks coexist. The high-speed carrier cco communication module 21 of this network will listen to the high-speed carrier cco communication module 21 of the neighboring network to coordinate the bandwidth usage time and ensure normal communication of multiple networks.

[0106] The concurrent meter reading mechanism adopts the principle of sending multiple frames of meter reading messages at one time, and each frame of message contains multiple data items, significantly improving the meter reading efficiency.

[0107] Embodiment 1:

[0108] See Figures 1 to 2 , a plug-and-play distribution network system, the distribution network system includes: a distribution network automation master station 1, a fusion terminal 2, a plurality of primary equipment 3 and a plurality of secondary equipment 4;

[0109] The fusion terminal 2 is provided with a high-speed carrier cco communication module 21, and the fusion terminal 2 is signal-connected to the high-speed carrier cco communication module 21 provided thereon,

[0110] Each of the primary equipment 3 and the secondary equipment 4 is provided with a STA module 5, and each of the primary equipment 3 and the secondary equipment 4 is signal-connected to the STA module 5 provided thereon;

[0111] The distribution network automation master station 1 is signal-connected to the fusion terminal 2, the fusion terminal 2 is signal-connected to the high-speed carrier cco communication module 21, and the high-speed carrier cco communication module 21 is simultaneously signal-connected to all STA modules 5 in the distribution network;

[0112] The distribution network automation master station 1 is used for ledger confirmation and file distribution. The fusion terminal 2 is used for access rule setting and characteristic current identification. The high-speed carrier cco communication module 21 and the STA module 5 are used to implement high-speed carrier communication in the distribution network;

[0113] The fusion terminal 2 is used to automatically identify newly connected secondary equipment 4 in the distribution network and manage and control the secondary equipment 4.

[0114] The fusion terminal 2 is also used to select the optimal access point location of the secondary equipment 4 in the distribution network.

[0115] Embodiment 2:

[0116] See Figure 4 , a networking method for a plug-and-play distribution network system, the networking method comprising the following steps:

[0117] S1. Device registration. The fusion terminal 2 sends registration information to the distribution network automation master station 1. When the distribution network automation master station 1 receives the registration information, it enters S2;

[0118] S2. Issuing a device description file. After receiving the registration information, the distribution network automation master station 1 sends the next device description file in the substation area to the fusion terminal 2. When the fusion terminal 2 receives the next device description file in the substation area, it enters S3;

[0119] S3. Device description file parsing. The fusion terminal 2 parses the received next device description file in the substation area to obtain the PMS_ID. After obtaining the PMS_ID, the fusion terminal 2 sends the PMS_ID to each secondary device 4 in the distribution network. When the secondary device 4 receives the PMS_ID, it enters S4;

[0120] S4. Device mapping. After each primary device 3 and secondary device 4 in the distribution network receives the PMS_ID, the STA module 5 on the primary device 3 and secondary device 4 sends feedback information to the fusion terminal 2 through a carrier signal. After receiving the feedback information, the fusion terminal 2 performs registration discovery on the newly connected secondary device 4 and enters S5;

[0121] S5. Establish device mapping. The communication module of the fusion terminal 2 performs primary and secondary device mapping on all secondary devices 4 respectively, generates an intelligent electronic device capability description file based on the mapping results of the primary and secondary devices, and instantiates the intelligent electronic device capability description file. After the instantiation of the intelligent electronic device capability description file is completed, proceed to S6;

[0122] S6. The communication module of the fusion terminal 2 communicates with the secondary device normally, and transmits the IED instance configuration file of this type of device generated by the communication module to the fusion terminal 2. The fusion terminal 2 forms a total IED instance configuration file for the substation area and uploads it to the distribution network automation master station 1. The total IED instance configuration file for the substation area contains all data points in the substation area and the data points default to be uploaded to the master station. After the distribution network automation master station 1 receives the total IED instance configuration file for the substation area, proceed to S7;

[0123] S7. Generate a CID file. The distribution network automation master station 1 receives the IED instance configuration file uploaded by the fusion terminal 2, parses the IED instance configuration file uploaded by the fusion terminal 2, establishes a communication model on the master station side according to the parsing results, and automatically completes the subscription to the data set to generate a CID file. The data set includes the operation data of the distribution transformer corresponding to the fusion terminal 2 in the substation area, the device conditions and operation data of each primary device 3 connected to the low-voltage power grid.

[0124] The device mapping in S4 includes the following steps:

[0125] After each primary device 3 and secondary device 4 in the distribution network receives the PMS_ID, the STA module 5 on the primary device 3 and secondary device 4 sends feedback information to the fusion terminal 2 through a carrier signal. After the fusion terminal 2 receives the feedback information, it registers and discovers the newly connected secondary device 4 and proceeds to S5.

[0126] The device mapping in S4 includes the following steps:

[0127] When the newly added secondary device 4 is installed in the distribution network, the secondary device 4 sends a request message to the high-speed carrier cco communication module 21 set on the fusion terminal 2 through the STA module 5 set on it. The request message includes. After the fusion terminal 2 receives the request message, it sends the registration communication address, device type, and the corresponding primary device PMS_ID to the secondary device 4 that sent the request message through the high-speed carrier cco communication module 21.

[0128] The networking method further includes the following steps:

[0129] S8. Identify the node access location and line. The distribution network automation master station 1 sends the CID file with the set data set to the fusion terminal 2. The fusion terminal 2 parses the received CID file, generates a communication model for information interaction between the fusion terminal 2 and the distribution network automation master station 1 according to the parsing result, and conducts information interaction with the master station through the standard protocol.

[0130] The communication model on the master station side includes the master station layer, the regional layer, and the local layer. The master station layer is the distribution network automation master station 1, the regional layer is the fusion terminal 2, and the local layer is the secondary equipment 4. The master station layer, the regional layer, and the local layer jointly form a three-level communication architecture through their corresponding high-speed carrier cco communication modules 21 and STA modules 5.

[0131] The S8 for identifying the node access location and line includes the following steps:

[0132] Collect the voltages U of each transformer in the distribution network a and the voltages u b ′ of each terminal device. Perform dimensionless processing on the voltage information U a and u b ′ to obtain the normalized value U a ′ of the low-voltage side voltage of transformer a and the normalized value U″ of the access point voltage of dimensionless terminal device b. b The expressions for U a ′ and u″ b are:

[0133]

[0134]

[0135] In the above formula, t is the t-th acquisition point of the voltage data, and 1 represents the first voltage data acquisition point in the distribution network;

[0136] Calculate the voltage fluctuation similarity coefficient θ ab (t) of the terminal device and the transformer. The expression for the voltage fluctuation similarity coefficient θ ab (t) is:

[0137]

[0138] In the above formula, Δu ab (t) = |u″ b (t) - U′ a (t)|, σ is the discrimination coefficient, min a min b Δu ab (t) means taking the value of Δu ab (t) corresponding to the minimum voltage of the low-voltage side of the t-th transformer, that is, the minimum tap ratio, maxa max b Δu ab (t) is the Δu corresponding to the maximum voltage at the low-voltage side of the t-th transformer, i.e., when the tap ratio is the largest. ab (t);

[0139] Calculate the voltage fluctuation correlation degree between the terminal device and the transformer. The voltage fluctuation correlation degree The expression is:

[0140]

[0141] Any terminal device belongs to the transformer substation where the transformer with the highest correlation degree is located.

[0142] The S5 device mapping establishment includes the following steps:

[0143] After the fusion terminal 2 receives the feedback information, it establishes the primary-secondary device mapping for all secondary devices 4. If the PMS_ID information of the secondary device 4 can be found in the primary device PMS_ID list, the primary-secondary device mapping of this secondary device 4 is successfully established. If the PMS_ID information of any secondary device 4 cannot be found in the primary device PMS_ID list, the primary-secondary device mapping of this secondary device 4 fails. After all secondary devices 4 have completed the primary-secondary device mapping, the fusion terminal 2 generates a list of secondary devices with successful mapping and a list of secondary devices with failed mapping according to the mapping results, and generates a smart electronic device capability description file according to the mapping results. At the same time, it instantiates the smart electronic device capability description file. After the instantiation of the smart electronic device capability description file is completed, it enters S6.

[0144] Embodiment 3:

[0145] Refer to Figure 5 , a method for selecting an access point of a plug-and-play distribution network system. When the distribution network system needs to newly access a secondary device 4, the fusion terminal 2 runs the access point selection method;

[0146] The access point selection method includes the following steps:

[0147] Step 1: Establish a distributed power optimization connection point model. The distributed power optimization connection point model includes the node power flow balance condition under critical conditions, the reactive power limit condition under critical conditions, the power reverse flow limit condition under critical conditions, the voltage deviation limit condition under critical conditions, and the line capacity limit condition under critical conditions. Define the total number of nodes in the distributed power optimization connection point model as N, and sort them from 1 to N. Assume that the node where the distributed power is connected during the calculation of the distributed power optimization connection point model is node i, and the j-th node among the N nodes of the distributed power optimization connection point model is node j. The node power flow balance condition under critical conditions includes the active power and reactive power injected by node i. The expression for the active power injected by the node is:

[0148]

[0149] The expression for the reactive power injected by the node is:

[0150]

[0151] In the above formula, P s,i is the active power injected by node i, Q s,i is the reactive power injected by node i, U i is the voltage amplitude of node i, U j is the voltage amplitude of node j, G i,j is the real part of the system admittance matrix, B i,j is the imaginary part of the system admittance matrix, θ i,j is the voltage phase angle difference between node i and j;

[0152] The expression for the reactive power limit condition under critical conditions is:

[0153]

[0154] The S DGk is the capacity of the distributed power connected at the voltage data acquisition point k, P DGk is the active power generated by the distributed power at the voltage data acquisition point k, Q DGk is the reactive power generated by the distributed power at the voltage data acquisition point k;

[0155] The expression for the power reverse flow limit condition under critical conditions is:

[0156] η DG，t P DGk，max ≤η Load ,P Load，max +βR Load，max ;

[0157] In the above formula, P DGk，max$P$ is the maximum output power of the distributed power source. Load，max $\eta$ is the maximum load of the distributed power source. DG，t $\eta$ is the ratio of the active power output of the distributed power source at time $t$ to its maximum output. load，t $\beta$ is the ratio of the load at time $t$ to the maximum load of the network. $\beta$ is the power flow reverse coefficient. When $\beta = 0$, reverse power flow at the head end is not allowed.

[0158] The expression for the voltage deviation limit condition under the critical condition is:

[0159] $\Delta U\%$ min $\leq (U$ i $- U$ e ) / U e $\leq \Delta U\%$ max ;

[0160] In the above formula, $U$ e is the rated voltage, $\Delta U\%$ min is the upper limit of the voltage deviation, $\Delta U\%$ max is the lower limit of the voltage deviation;

[0161] The expression for the line capacity limit condition under the critical condition is:

[0162] $S$ Lm $\leq S$ Lm，max ;

[0163] $S$ Lm is the current apparent power of line $m$, $S$ Lm，max is the maximum allowable capacity of line $m$;

[0164] Second step, simplify the optimized access point model of the distributed power source. By replacing the leading power factor in the distributed power source with a lagging power factor, the expression for the reactive power injected into the node after simplification is:

[0165]

[0166] In the above formula is the maximum lagging power factor during the operation of the distributed power source;

[0167] Take the moment corresponding to the minimum load and the maximum output of the distributed power source in the prediction curve as the critical condition for the power flow reverse limit condition. The expression for the power flow reverse limit condition under the simplified critical condition is:

[0168]

[0169] By selecting nodes, the branch load is equivalent to the connection point, simplifying the tree - shaped topological structure to a single - radiation topology. During the calculation of voltage drop, the influence of the transverse component is ignored, and at the same time, it is assumed that the denominator of the longitudinal component of the voltage drop is the rated voltage $U$ e, obtain the approximate expression of the voltage deviation at the grid connection point k:

[0170]

[0171] In the above formula, ΔU k % is the voltage deviation at the voltage data acquisition point k, N is the total number of nodes, P L,k is the maximum active load of node k, Q L,k is the maximum reactive load of the voltage data acquisition point k;

[0172] In the third step, calculate the functional relationship between the maximum access power of the distributed power source and the voltage deviation. Substitute the simplified reactive power expression injected into the node into the approximate expression of the voltage deviation at the grid connection point k to obtain the expression of the functional relationship between the maximum access power of the distributed power source and the voltage deviation as:

[0173]

[0174] In the above formula, P DGk,max(V) is the estimated value of the plug-and-play critical condition of the distributed power source. α is the loss correction coefficient, which is used to compensate for the underestimated value caused by ignoring the losses in the network. The loss correction coefficient α is equal to the ratio of the total power supply to the total power consumption of the network before the distributed power source is connected;

[0175] In the fourth step, calculate the power flow flowing through each node after the distributed power source is connected to the grid. Assume that the capacity of each section of the line is S L , ignoring the losses in the network, the power flow flowing through each node after the distributed power source is connected to the grid, and the approximate expression of the power flow flowing through each node after the distributed power source is connected to the grid is;

[0176]

[0177] In the above formula, is the approximate value of the node power corresponding to the end node of the line model, is the approximate value of the node power corresponding to the node adjacent to the end node in the line model, is the approximate value of the node power corresponding to the node adjacent to the end node in the direction of the voltage data acquisition point k in the line model, is the approximate value of the node power corresponding to the voltage data acquisition point k in the line model, is the approximate value of the node power corresponding to the starting node of the line model;

[0178] In the fifth step, simplify the line capacity constraint. Only consider that the power flow at the access point k does not exceed the line allowable capacity, and obtain the simplified expression of the line capacity constraint as:

[0179]

[0180] In the above formula, is the estimated value of the plug-and-play critical condition of distributed power sources, and S L is the line capacity, is the minimum power factor allowed for the line;

[0181] Step 6: Obtain the access point location. By solving the optimized access point model of distributed power sources, the optimal power corresponding to the nearest access point for the device to be connected is obtained. The expression of the optimal power is:

[0182]

[0183] In the above formula, maxP DG is the optimal power corresponding to the nearest access point for the device to be connected. Compare the maximum output of the distributed power source with the optimal power corresponding to the nearest access point. When the optimal power corresponding to the nearest access point is greater than the maximum output of the distributed power source, this nearest access point is the optimal access location;

[0184] If the optimal power corresponding to the nearest access point is less than the maximum output of the distributed power source, then select the access points on both sides of this nearest access point to calculate the optimal power until the optimal power corresponding to the selected access point is greater than the maximum output of the distributed power source.

[0185] The above is only the preferred embodiment of the present invention, and the protection scope of the present invention is not limited to the above embodiment. Any equivalent modification or change made by those of ordinary skill in the art according to the content disclosed by the present invention shall be included in the protection scope recorded in the claims.

Claims

1. A plug-and-play distribution network system, characterized in that: The distribution network system comprises: a distribution network automation master station (1), a fusion terminal (2), a plurality of primary devices (3) and a plurality of secondary devices (4); The fusion terminal (2) is provided with a high-speed carrier CCO communication module (21), and the fusion terminal (2) is signal-connected to the high-speed carrier CCO communication module (21) provided thereon. Each of the primary devices (3) and the secondary devices (4) is provided with a STA module (5), and each of the primary devices (3) and the secondary devices (4) is signal-connected to the STA module (5) provided thereon; The distribution network automation master station (1) is signal-connected to the fusion terminal (2), the fusion terminal (2) is signal-connected to the high-speed carrier cco communication module (21), and the high-speed carrier cco communication module (21) is simultaneously signal-connected to all STA modules (5) in the distribution network; The distribution network automation master station (1) is used for confirming the ledger and issuing the file, the fusion terminal (2) is used for setting the network access rules and identifying the characteristic current, and the high-speed carrier cco communication module (21) and the STA module (5) are used for realizing high-speed carrier communication in the distribution network; The fusion terminal (2) is used to automatically identify a secondary device (4) newly connected to the distribution network, and to manage and control the secondary device (4); The fusion terminal (2) is also used to select the optimal access point location of the secondary equipment (4) in the distribution network; The fusion terminal (2) collects the voltage U of each transformer in the distribution network from the characteristic current a And the voltage of each terminal device u b ′, and the voltage information U a and u b ′ is processed dimensionlessly to obtain the normalized value U of the low-voltage side voltage of transformer a a ′ and dimensionless normalized voltage value U″ at the access point of terminal device b b , through the normalized value U of the low-voltage side voltage of transformer a a ′ and dimensionless normalized voltage value U″ at the access point of terminal device b b Calculate the voltage fluctuation similarity coefficient θ between the terminal device and the transformer ab (t), the voltage fluctuation similarity coefficient θ ab The expression of (t) is: In the above formula, Δu ab (t)=|u″ b (t)-U′ a (t)|, σ is the resolution coefficient, min a min b Δu ab (t) is the Δu corresponding to the minimum voltage on the low-voltage side of the t-th transformer, that is, the minimum tap ratio. ab (t) value, max a max b Δu ab (t) is the Δu corresponding to the maximum voltage on the low-voltage side of the t-th transformer, that is, the maximum tap ratio. ab The value of (t); Calculate the correlation between voltage fluctuations of the terminal equipment and the transformer The voltage fluctuation correlation The expression is: Any end device belongs to the substation where the transformer with the highest correlation degree is located.

2. A networking method for a plug-and-play power distribution network system according to claim 1, characterized in that: The networking method comprises the following steps: S1, device registration, the fusion terminal (2) sends registration information to the distribution network automation master station (1), and when the distribution network automation master station (1) receives the registration information, it enters S2; S2, issuing the device description file. After receiving the registration information, the distribution network automation master station (1) sends the next device description file of the substation to the fusion terminal (2). After the fusion terminal (2) receives the next device description file of the substation, it enters S3; S3, device description file parsing, the fusion terminal (2) parses the received next device description file of the substation to obtain the PMS_ID. After obtaining the PMS_ID, the fusion terminal (2) sends the PMS_ID to each secondary device (4) in the distribution network. When the secondary device (4) receives the PMS_ID, it enters S4; S4, device mapping. After each primary device (3) and secondary device (4) in the distribution network receives the PMS_ID, the STA module (5) on the primary device (3) and the secondary device (4) sends feedback information to the fusion terminal (2) through a carrier signal. After receiving the feedback information, the fusion terminal (2) registers and discovers the newly connected secondary device (4) and enters S5. S5, establishing device mapping, the communication module of the fusion terminal (2) performs primary and secondary device mapping on all secondary devices (4) respectively, and generates an intelligent electronic device capability description file according to the primary and secondary device mapping establishment results, and instantiates the intelligent electronic device capability description file at the same time. When the instantiation of the intelligent electronic device capability description file is completed, enter S6; S6, the communication module of the fusion terminal (2) communicates normally with the secondary device, and transmits the IED instance configuration file of this type of device generated by the communication module to the fusion terminal (2), and the fusion terminal (2) generates a total IED instance configuration file of the substation area and sends it to the distribution network automation master station (1), wherein the total IED instance configuration file of the substation area includes all data points in the substation area and the data points sent to the master station by default. When the distribution network automation master station (1) receives the total IED instance configuration file of the substation area, it enters S7; S7, generating a CID file, the distribution network automation master station (1) receives the IED instance configuration file sent by the fusion terminal (2), and parses the IED instance configuration file sent by the fusion terminal (2), establishes a master station side communication model according to the parsing result, and automatically completes the subscription of the data set to generate a CID file, wherein the data set includes the distribution transformer operation data corresponding to the fusion terminal (2), and the equipment status and operation data of each primary device (3) connected to the corresponding low-voltage power grid.

3. The networking method of a plug-and-play power distribution network system according to claim 2, characterized in that: The S4 device mapping includes the following steps: After each primary device (3) and secondary device (4) in the distribution network receives the PMS_ID, the STA module (5) on the primary device (3) and the secondary device (4) sends feedback information to the fusion terminal (2) through a carrier signal. After receiving the feedback information, the fusion terminal (2) registers and discovers the newly connected secondary device (4) and enters S5.

4. The networking method of a plug-and-play power distribution network system according to claim 2, characterized in that: The S4 device mapping includes the following steps: When a newly added secondary device (4) is installed in the distribution network, the secondary device (4) sends a request message to a high-speed carrier cco communication module (21) provided on the fusion terminal (2) through a STA module (5) provided thereon, wherein the request message includes, when the fusion terminal (2) receives the request message, sending a registered communication address, a device type and a corresponding primary device PMS_ID to the secondary device (4) that sends the request message through the high-speed carrier cco communication module (21).

5. A method for networking a plug-and-play power distribution network system according to claim 3 or 4, characterized in that: The networking method further comprises the following steps: S8, identifying the node access location and line, the distribution network automation master station (1) sends the CID file of the set data set to the fusion terminal (2), the fusion terminal (2) parses the received CID file, and generates a communication model for information interaction between the fusion terminal (2) and the distribution network automation master station (1) according to the parsing result, and exchanges information with the master station through standard protocols.

6. The networking method of a plug-and-play power distribution network system according to claim 5, characterized in that: The master station side communication model comprises a master station layer, a regional layer and a local layer, wherein the master station layer is a distribution network automation master station (1), the regional layer is a fusion terminal (2), and the local layer is a secondary device (4). The master station layer, the regional layer and the local layer together form a three-level communication architecture through their corresponding high-speed carrier cco communication modules (21) and STA modules (5).

7. The networking method of a plug-and-play power distribution network system according to claim 6, characterized in that: The step S8 of identifying the node access location and line includes the following steps: The U a ′ and u″ b The expression is: In the above formula, t is the tth voltage data collection point, and 1 represents the first voltage data collection point in the distribution network.

8. The networking method of a plug-and-play power distribution network system according to claim 7, characterized in that: The S5 device mapping establishment comprises the following steps: After receiving the feedback information, the fusion terminal (2) establishes a primary and secondary device mapping for all secondary devices (4). If the PMS_ID information of the secondary device (4) can be found in the primary device PMS_ID list, the primary and secondary device mapping of the secondary device (4) is successfully established. If the PMS_ID information of any secondary device (4) cannot be found in the primary device PMS_ID list, the primary and secondary device mapping of the secondary device (4) fails to be established. After all secondary devices (4) have been mapped to the primary and secondary devices, the fusion terminal (2) generates a list of successfully mapped secondary devices and a list of unmapped secondary devices according to the results of the primary and secondary device mapping, and generates an intelligent electronic device capability description file according to the mapping results, and instantiates the intelligent electronic device capability description file at the same time. After the instantiation of the intelligent electronic device capability description file is completed, enter S6.

9. A method for selecting an access point of a plug-and-play distribution network system according to claim 1, characterized in that: When the distribution network system needs to newly access a secondary device (4), the fusion terminal (2) runs an access point selection method; The access point selection method comprises the following steps: The first step is to establish a distributed power supply optimization access point model, which includes node power flow balance conditions under critical conditions, reactive power restriction conditions under critical conditions, power flow reverse restriction conditions under critical conditions, voltage deviation restriction conditions under critical conditions, and line capacity restriction conditions under critical conditions. The total number of nodes in the distributed power supply optimization access point model is defined as N, and they are sorted from 1-N. The node to which the distributed power supply is connected during the calculation of the distributed power supply optimization access point model is node i, and the jth node among the N nodes of the distributed power supply optimization access point model is node j. The node power flow balance condition under critical conditions includes the active power and reactive power injected by node i, and the expression of the active power injected by the node is: The reactive power expression injected by the node is: In the above formula, P s,i is the active power injected into node i, Q s,i is the reactive power injected into node i, U i is the voltage amplitude at node i, U j is the voltage amplitude at node j, G i,j is the real part of the system admittance matrix, B i,j is the imaginary part of the system admittance matrix, θ i,j is the voltage phase angle difference between nodes i and j; The expression of the reactive power limitation condition under the critical condition is: The S DGk is the capacity of the distributed power source connected to the voltage data collection point k, P DGk is the active power generated by the distributed power source at the voltage data collection point k, Q DGk is the reactive power generated by the distributed power source at the voltage data collection point k; The expression of the power flow backflow restriction condition under the critical condition is: or DG，t P DGk,max ≤η Load ,P Load,max +βP Load,max ; In the above formula, P DGk,max is the maximum output power of distributed power source, P Load,max is the maximum load of distributed generation, η DG,t is the ratio of the active output of the distributed generation to its maximum output at time t, η load,t is the ratio of the load at time t to the maximum load of the network, β is the power flow reverse transmission coefficient, when β = 0, the head-end power flow reverse transmission is not allowed; The expression of the voltage deviation limiting condition under the critical condition is: ΔU% min ≤(U i -U e ) / U e ≤ΔU% max ; In the above formula, U e is the rated voltage, △U% min Is the upper limit of voltage deviation, △U% max is the lower limit of voltage deviation; The expression of the line capacity limitation condition under the critical condition is: S Lm ≤S Lm，max ; S Lm is the current apparent power of line m, S Lm,max is the maximum allowed capacity of line m; In the second step, the optimized access point model of distributed power sources is simplified by replacing the leading power factor in the distributed power sources with the lagging power factor. The expression of the reactive power injected by the simplified node is obtained as follows: In the above formula Maximum lagging power factor for distributed power generation operation; The time corresponding to the minimum load and maximum output of distributed generation in the prediction curve is taken as the critical condition of the power flow backfeed restriction condition, and the expression of the power flow backfeed restriction condition under the simplified critical condition is obtained as follows: By selecting nodes to equate the branch load to the access point, the tree topology is simplified to a single radial topology. The influence of the horizontal component is ignored in the calculation of the voltage drop, and the denominator of the vertical component of the voltage drop is assumed to be the rated voltage U e , we get the approximate expression of the voltage deviation at the grid connection point k: In the above formula, ΔU k % is the voltage deviation at the voltage data collection point k, N is the total number of nodes, P L,k is the maximum active load of node k, Q L,k is the maximum reactive load at the voltage data collection point k; The third step is to calculate the functional relationship between the maximum access power of the distributed generation and the voltage deviation. Substitute the simplified reactive power expression injected by the node into the approximate expression of the voltage deviation at the grid connection point k, and the functional relationship between the maximum access power of the distributed generation and the voltage deviation is obtained as follows: In the above formula, P DGk,max(V) is the estimated value of the plug-and-play critical condition of distributed generation, α is the loss correction coefficient, which is used to compensate for the smaller estimated value caused by ignoring the loss in the network. The loss correction coefficient α is equal to the ratio of the total power supply to the total power consumption of the network before the distributed generation is connected; The fourth step is to calculate the power flow at each node after the distributed generation is connected to the grid, assuming that the capacity of each section of the line is S L , ignoring the loss in the network, the approximate expression of the power flow flowing on each node after the distributed generation is connected to the grid is; In the above formula, is the approximate value of the node power corresponding to the end node of the line model, is the approximate value of the node power corresponding to the node adjacent to the end node in the line model, is the approximate value of the node power corresponding to the node adjacent to the terminal node in the voltage data collection point k in the line model, is the approximate value of the node power corresponding to the voltage data collection point k in the line model, is the approximate value of the node power corresponding to the starting node of the line model; The fifth step is to simplify the line capacity constraint, and only consider that the flow at access point k does not exceed the allowed capacity of the line. The expression of the simplified line capacity constraint is: In the above formula, is the estimated value of the critical condition of distributed generation plug and play, S L is the line capacity, is the minimum power factor allowed by the line; The sixth step is to obtain the access point location, and obtain the optimal power corresponding to the nearest access point corresponding to the device to be connected by solving the distributed power supply optimization access point model. The expression of the optimal power is: In the above formula, max P DG The optimal power corresponding to the nearest access point corresponding to the device to be connected is compared with the maximum output of the distributed power source and the optimal power corresponding to the nearest access point. When the optimal power corresponding to the nearest access point is greater than the maximum output of the distributed power source, the nearest access point is the optimal access location; If the optimal power corresponding to the nearest access point is less than the maximum output of the distributed power source, the access points on both sides of the nearest access point are selected to calculate the optimal power until the optimal power corresponding to the selected access point is greater than the maximum output of the distributed power source.

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