Intelligent power distribution network emergency stability control method of communication architecture based on time label

Abstract

The invention discloses an intelligent power distribution network emergency stability control method of a communication architecture based on a time label. The method comprises the following steps: step 1) constructing a load flow calculation model containing dynamic characteristics of power electronic equipment; 2) measuring state data information of power electronic equipment in different areas of the power distribution network, and determining a fault state of the power electronic equipment and whether an auxiliary service instruction needs to be issued to the power electronic equipment according to the state data information of each power electronic equipment; and (3) controlling the inverter according to a set method after the fault state of each power electronic device is obtained in the step (2). According to the method, the power distribution network is accurately monitored through real-time load flow calculation, the line crossing condition is rapidly identified, high-speed transmission and accurate positioning of fault information are realized in combination with a time label communication architecture, the system stability is rapidly recovered, and the influence of faults on the power distribution network is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of power systems, and in particular to an emergency stability control method for an intelligent distribution network based on a communication architecture of a time tag. Background Art

[0002] The distribution network is an important part of the power system. It is responsible for transmitting electricity from the source (such as distributed photovoltaic, distributed wind power, energy storage, etc.) to the load (electric vehicles, charging piles and fixed loads, etc.) to ensure the safe, reliable and efficient supply of electricity. The distribution network generally includes a variety of power electronic equipment, such as rectifiers, inverters, frequency converters, reactive power compensation devices, and power electronic transformers.

[0003] In modern distribution networks, power flow calculation is a key tool for evaluating the operating status of distribution networks and ensuring the safety and stability of the system. Traditional power flow calculation methods rely on static analysis, and determine the operating status of the system by solving the voltage, current and power flow conditions of each node in the distribution network. With the expansion of the scale and increase in complexity of the distribution network, the traditional power flow calculation method has certain limitations under high load, nonlinear and time-varying conditions. Especially in the face of complex working conditions such as frequent fluctuations in the distribution network, dynamic changes in loads and high-voltage faults, the power flow calculation cannot reflect the status of the distribution network in real time, and the calculation process is relatively lengthy and the response speed is insufficient. This delayed power flow calculation result often cannot detect the line crossing in the distribution network (such as voltage overlimit, current abnormality, power flow imbalance, etc.) in time at the early stage of the fault, thereby delaying the system's early warning and emergency response, and increasing the risk of large-scale failures in the power system. Therefore, how to achieve more real-time and accurate power flow calculation in complex power networks is a very worthy issue to study.

[0004] In addition, the stability and response speed of the distribution network are closely related to the performance of the communication architecture. In traditional power systems, the communication system is mainly responsible for tasks such as fault detection, control command transmission and monitoring data feedback. However, in practical applications, traditional communication architectures generally have problems such as limited bandwidth, high transmission delay and information asymmetry. Especially in complex distribution networks, the stability and real-time performance of the communication network directly affect the emergency response capability of the system. When a fault occurs, the communication delay between the sensor and the control unit in the distribution network may cause information lag, thereby delaying the start of fault diagnosis and stable control. The traditional point-to-point communication architecture and a single communication protocol cannot support cross-regional and cross-device collaboration, resulting in the difficulty in ensuring the real-time and accuracy of information transmission in complex fault scenarios. In addition, the existing communication system has weak anti-interference ability when encountering high load or harsh environment, and often cannot ensure the rapid transmission of key information under extreme conditions. Therefore, improving the real-time, reliability and cross-system collaboration capabilities of the power system communication architecture has become an urgent need to improve the emergency stability and response speed of the distribution network.

[0005] Furthermore, the emergency stability control methods of traditional distribution networks mainly include overcurrent protection and reclosing technology. Although they can effectively deal with power system faults to a certain extent, they have significant limitations under the complexity and dynamic requirements of modern power systems. Overcurrent protection technology identifies short-circuit faults by real-time monitoring of abnormal current increases and quickly disconnects the faulty line to reduce damage to equipment. However, the main drawback of this method is that its recovery process is relatively slow. After the fault is removed, the system needs to be restarted and synchronized. This process is often accompanied by long-term oscillations, resulting in drastic fluctuations in voltage and frequency, which affects the stability and power supply quality of the power system. Reclosing technology aims to quickly restore power supply through an automatic closing mechanism, reduce power outage time, and improve system reliability. However, if the fault is not completely eliminated or there are unstable factors in the system recovery process, reclosing may cause secondary faults, further exacerbating the volatility and uncertainty of the system. Especially in the case of high load or complex power networks, the reliability of reclosing technology is low, and it may not be able to effectively restore the stability of the system, or even cause a larger range of system failures. For complex power networks or high load conditions, this low reliability makes it difficult for power systems to meet modern needs for high stability and rapid response. Summary of the invention

[0006] In view of the above-mentioned deficiencies in the prior art, the technical problem to be solved by the present invention is: how to provide an emergency stability control method for an intelligent distribution network based on a time tag communication architecture, which can accurately monitor the distribution network through real-time power flow calculation, quickly identify line crossing situations, and combine the time tag communication architecture to achieve high-speed transmission and precise positioning of fault information, and quickly restore system stability and reduce the impact of faults on the distribution network.

[0007] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0008] A method for emergency stability control of a smart distribution network based on a communication architecture of a time tag comprises the following steps:

[0009] Step 1) constructing a power flow calculation model including dynamic characteristics of power electronic equipment;

[0010] Step 2) measuring the status data information of power electronic devices in different areas of the distribution network, and determining the fault status of the power electronic devices according to the status data information of each power electronic device, and whether an auxiliary service instruction needs to be issued to the power electronic devices;

[0011] Step 3) After the fault status of each power electronic device is obtained in step 2), the inverter is controlled according to the setting method.

[0012] Preferably, step 1) includes the following steps:

[0013] Step 1.1) Establish a dynamic characteristic model of power electronic equipment in power flow calculation;

[0014] Step 1.2) construct a power flow calculation model based on the electrical characteristics and control characteristics of multiple types of converters in power electronic equipment;

[0015] Step 1.3) Use the power flow calculation model to monitor and analyze the operating status of the distribution network in real time.

[0016] Preferably, step 2) includes the following steps:

[0017] Step 2.1) The local server in each area continuously samples the status data information of the power electronic equipment in the corresponding area at the set time to obtain a sampled value, and obtains the current time as the time tag of the sampled value, and uploads the sampled value and the time tag to the cloud;

[0018] Step 2.2) The cloud selects the valid sampling value sequence of each power electronic device based on the sampling values ​​sent by the local servers in each region and the time tags;

[0019] Step 2.3) After obtaining the valid sampling value sequence of the power electronic equipment in each area, the power flow calculation of each power electronic equipment is performed according to step 1), and it is determined whether to send auxiliary service instructions to the power electronic equipment in each area according to the power flow calculation results.

[0020] Preferably, in step 2.1), the cloud sends a sampling signal, and after receiving the sampling signal, the local server in each area starts to sample the status data information of the power electronic equipment in the corresponding area for a period of T to obtain a sampling value, and at the same time obtains the current time as a time tag. After the sampling time T ends, the data is uploaded to the cloud, and the cloud retains the data with the same sampling time.

[0021] Preferably, in step 2.1), when the set of power electronic devices to be sampled is D, there is

[0022] D=[D1,D2,D3,D4,...D i ...]

[0023] Where D is the set of power electronic devices to be sampled, D i It is the status data information of specific power electronic equipment.

[0024] The sampling results of each power electronic device within T time are:

[0025]

[0026] in, D i Power electronics in t ii The sampling value at the time, D T for A collection of .

[0027] Preferably, in step 2.2), when the cloud screens out j At time , when each power electronic device has a corresponding sampling value, the effective sampling value sequence is:

[0028]

[0029] When the cloud cannot filter out all power electronic devices with sampling values, j At time t, find the time t when each power electronic device has the most sampling values f , and the rest at time t f Power electronic equipment without sampling value is f Find the effective time around the time. If the power electronic equipment D i No f time, and t ii satisfy:

[0030] |t f -t ii |≤ε

[0031] Among them, ε is the effective threshold, then the power electronic device is ii Sampling value at time Add to the effective value sampling value sequence;

[0032] At this time, the effective sampling value sequence of each power electronic device is:

[0033]

[0034] Preferably, in step 2.3), after obtaining the valid sampling value sequence of each power electronic device, the power flow calculation of each power electronic device is performed according to step 1) to obtain:

[0035]

[0036] in, is the effective sampling value of the i-th power electronic device after power flow calculation;

[0037] The safety threshold of each power electronic device is set as:

[0038]

[0039] in, is the safety threshold corresponding to the i-th power electronic device;

[0040] if The elements in D are greater than s The elements in can get the following control sequence:

[0041]

[0042] in, The execution logic meets the following process:

[0043] when hour, is True, indicating that the i-th power electronic device requires an auxiliary service instruction;

[0044] when hour, is False, indicating that the i-th power electronic device does not require an auxiliary service instruction.

[0045] Preferably, the setting method in step 3) comprises the following steps:

[0046] Step 3.1) Obtain the three-phase voltage V on the inverter side abc , three-phase voltage U on the distribution network sideabc And the three-phase current I abc , and perform coordinate transformation on these electrical signals;

[0047] Step 3.2) Calculate the phase angle on the inverter side and the phase angle on the distribution network side according to the converted three-phase voltage on the inverter side, the three-phase voltage on the distribution network side, and the three-phase current on the distribution network side;

[0048] Step 3.3) Calculate the power angle difference and the phase compensation angle according to the phase angle on the inverter side and the phase angle on the distribution network side;

[0049] Step 3.4) The power angle is adjusted according to the calculated phase compensation angle to generate an inverter control signal.

[0050] Preferably, in step 3.2), the converted three-phase voltage on the inverter side, the three-phase voltage on the distribution network side, and the three-phase current on the distribution network side are input into a phase-locked loop to calculate the phase angle on the inverter side and the phase angle on the distribution network side;

[0051] The phase-locked loop module includes a PI controller and an integral operation module. The PI controller adjusts the phase of the input voltage, and then inputs the adjusted voltage into the integral operation module to obtain the phase angle θ on the inverter side. v and the phase angle θ on the grid side u .

[0052] Preferably, in step 3.3), a fuzzy PID controller is used to calculate the phase compensation angle δ of the power angle, and the calculation formula of δ is:

[0053]

[0054] e δ =δ ref -(θ v -θ u )

[0055]

[0056] Where: ref is the phase angle reference value, e δ is the power angle error, Δe δ is the rate of change of the power angle error, δe δ dt is the integral of the power angle error, μ i is the membership degree of the corresponding fuzzy rule, δ i is the output of the corresponding fuzzy rule.

[0057] Preferably, in step 1.1), a dynamic characteristic model of a virtual synchronous generator is established, and the adopted virtual synchronous generator model mainly includes a dual-loop control structure for controlling frequency and voltage amplitude, wherein a power control loop is used for frequency regulation, and a reactive power control loop is used for voltage amplitude regulation;

[0058] Among them, the power angle calculation formula of the virtual synchronous generator is:

[0059]

[0060] Where: T m is the mechanical torque of the virtual synchronous generator, T e is the virtual synchronous generator and electromagnetic torque, D p is the damping coefficient of the virtual synchronous generator, J is the inertia coefficient of the virtual synchronous generator, and θ is the power angle;

[0061] The reactive power calculation formula of virtual synchronous generator is:

[0062]

[0063] Where: e q is the q-axis modulation voltage of the virtual synchronous generator, K a is the voltage gain coefficient, V set is the set value of the node voltage, U0 is the actual voltage value of the current node, Q set is the set reactive power value, Q is the actual reactive power value, n q is the reactive gain.

[0064] Preferably, in step 1.2), a power flow calculation model with multiple optimization objectives is established, which is expressed as:

[0065] F min =(f1(x,u),f2(x,u),f3(x,u),f4(x,u)…,f n (x,u)),u=[u1,u2,…,u D ]

[0066] The constraints are:

[0067] G i (x,u)≥0,i=1,2

[0068] H i (x,u)=0,i=1,2

[0069] Where: F min is the total set of optimization targets, f1(x,u) is optimization target 1, f2(x,u) is optimization target 2, and f n(x,u) is the optimization target n, x is the state variable, u is the control variable, D is the dimension of the control variable, G i (x,u) is the inequality constraint set of the i-th optimization objective, H i (x,u) is the set of equality constraints for the i-th optimization objective;

[0070] Among them, the active power and reactive power of power electronic equipment satisfy the following relationship:

[0071]

[0072] Where: U i is the voltage of the sending node i, is the voltage vector of the sending node i, U j is the voltage at the receiving node j, is the voltage vector of receiving node j, is the conjugate of the voltage at the receiving node j; R ij is the resistance of the branch between the sending node i and the receiving node j, X ij is the reactance of the branch between the sending node i and the receiving node j; P j is the active power of receiving node j, Q j is the reactive power of receiving node j;

[0073] To ensure the existence of a feasible power flow solution for the distribution network, we have

[0074]

[0075] Therefore, the static voltage stability index of the receiving node j can be defined as:

[0076]

[0077] The steady-state operation of the receiving node j must satisfy the following formula:

[0078]

[0079] Specifically, the set of equality constraints for each optimization objective includes:

[0080]

[0081] Where: P j is the active power of the jth receiving node, P j+1 is the active power of the j+1th receiving node, P L(j+1) is the active power of the distributed energy storage connected to the j+1th receiving node, R j,j+1 is the impedance between the jth receiving node and the j+1th receiving node, Q j is the reactive power of the jth receiving node, Xk,k+1 is the reactance between the jth receiving node and the j+1th receiving node, V j is the voltage per unit value of the jth receiving node.

[0082] Compared with the prior art, the present invention has the following advantages:

[0083] 1. The present invention establishes a virtual synchronous generator model that takes into account the influence of power electronics in the distribution network, and combines it with a specific communication architecture to achieve emergency stability control of the distribution network. Through real-time information transmission and sampling between the cloud server and each power electronic device, it can accurately restore the state of each power electronic device after a short-circuit fault in the power system, and generate a control sequence based on the sampled information, thereby improving the recovery speed and accuracy of the system. At the same time, a phase-locked loop is used to calculate the phase angle, and the power angle is adjusted by a PI controller to complete the power system fault recovery process. This control method can effectively improve the recovery ability of the power system when encountering a short-circuit fault, and ensure the safe and stable operation of the system.

[0084] 2. The present invention accurately monitors the distribution network through real-time power flow calculation, quickly identifies line crossing conditions (such as voltage overlimit, current anomaly, etc.), and combines the time tag communication architecture to achieve high-speed transmission and precise positioning of fault information. Through efficient information transmission, the system can start the intelligent decision-making algorithm as soon as a fault occurs, and select appropriate stability control measures such as load regulation, reactive power compensation, and power supply path reconstruction according to the state of the distribution network, so as to quickly restore system stability and reduce the impact of faults on the distribution network. This method can significantly improve the emergency response capability and system stability of the distribution network, especially under high load and complex environments.

[0085] 3. The present invention can realize the rapid detection, precise positioning and intelligent decision-making control of distribution network faults by introducing an intelligent control method based on a time tag communication architecture, thereby significantly improving the emergency response capability and stability of the distribution network. At the same time, the method shortens the fault recovery time, reduces system oscillations and voltage and frequency fluctuations, reduces the probability of secondary faults, and effectively improves the reliability and stability of the power system through intelligent dynamic reconfiguration and control strategy optimization. In addition, the continuous real-time monitoring and feedback mechanism ensures that the system can continue to optimize operation after a fault, further improving the long-term operation efficiency of the distribution network. Therefore, the present invention not only optimizes the stable control of the distribution network, but also enhances its recovery and self-adaptation capabilities in the event of sudden faults, and can ensure that the system maintains stability under high load and complex operating conditions, thereby enhancing the overall reliability and adaptability of the power system. The method of the present invention improves the overall reliability and adaptability of the power system, and also provides a wider range of application scenarios, adapting to the diversified needs of modern power systems.

[0086] 4. The present invention improves the power angle control of the inverter, and can quickly adjust the phase angle of the inverter output voltage after a short-circuit fault occurs, so that the phase angle difference between the inverter output voltage and the synchronous generator or the infinite power grid quickly approaches a stable state, thereby significantly shortening the system recovery time. This design greatly improves the response efficiency of the power system in emergencies. In addition, the present invention adopts a hierarchical control architecture and an optimized control strategy, which can effectively suppress voltage and frequency fluctuations during the recovery process, reduce system oscillations, improve power supply quality, and ensure the stable operation of the power system. This method is applicable to a variety of complex power system scenarios, including high loads and complex network conditions, and can ensure the stability and reliability of the system. The present invention is applicable to distribution network models, broadens the scope of practical application, and fully meets the requirements of modern power systems for rapid response and high reliability. BRIEF DESCRIPTION OF THE DRAWINGS

[0087] Attached Figure 1 It is a flow chart of the emergency stability control method of the smart distribution network based on the communication architecture of the time tag of the present invention;

[0088] Attached Figure 2 A radial structure diagram of a distribution network in an emergency stability control method for an intelligent distribution network based on a communication architecture of a time tag according to the present invention;

[0089] Attached Figure 3 A flow chart of communication sampling and uploading to the cloud in the method for emergency stability control of a smart distribution network based on a communication architecture of a time tag of the present invention;

[0090] Attached Figure 4 It is a structural block diagram of the phase-locked loop and power angle calculation compensation module in the intelligent distribution network emergency stability control method based on the communication architecture of the time tag of the present invention. DETAILED DESCRIPTION

[0091] In order to make the purpose, technical scheme and advantages of the embodiments of the present invention clearer, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. The components of the embodiments of the present invention generally described and shown in the drawings here can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the claimed invention, but merely represents selected embodiments of the present invention. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work belong to the scope of protection of the present invention.

[0092] It should be noted that similar numbers and letters represent similar items in the following drawings, so once an item is defined in one drawing, it does not need to be further defined and explained in the subsequent drawings. In the description of the present invention, it should be noted that the orientation or position relationship indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inside", "outside", etc. is based on the orientation or position relationship shown in the drawings, or the orientation or position relationship in which the invention product is usually placed when used, which is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation of the present invention. In addition, the terms "first", "second", "third", etc. are only used to distinguish the description, and cannot be understood as indicating or implying relative importance. In addition, the terms "horizontal", "vertical", etc. do not mean that the components are absolutely horizontal or suspended, but can be slightly tilted. For example, "horizontal" only means that its direction is more horizontal than "vertical", and does not mean that the structure must be completely horizontal, but can be slightly tilted. In the description of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "set", "install", "connect", and "connect" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0093] In this specific embodiment, a smart distribution network emergency stability control method based on a communication architecture of a time tag is provided, as shown in the attached Figure 1 As shown, the following steps are included:

[0094] Step 1) Construct a power flow calculation model that includes the dynamic characteristics of power electronic equipment. Combined with the voltage regulation, reactive power compensation and frequency control characteristics of power electronic equipment, a dynamic power flow equation is constructed to record the node voltage, line current and power flow crossing conditions.

[0095] Specifically, step 1) includes the following steps:

[0096] Step 1.1) Establish a dynamic characteristic model of power electronic equipment in power flow calculation.

[0097] This solution fully considers the dynamic impact of power electronic equipment on power transmission in the distribution network during the modeling process. Based on the virtual synchronous generator model, combined with the common converter control strategies in the source-side (such as distributed photovoltaic, distributed wind power, energy storage) and load-side (electric vehicles, charging piles and fixed loads, etc.) equipment, a single-unit model is constructed and applied to network simulation analysis.

[0098] The dynamic characteristic model of the virtual synchronous generator is established. The virtual synchronous generator model mainly includes a dual-loop control structure for controlling frequency and voltage amplitude, in which the power control loop is used for frequency regulation and the reactive power control loop is used for voltage amplitude regulation.

[0099] Among them, the power angle calculation formula of the virtual synchronous generator is:

[0100]

[0101] Where: T m is the mechanical torque of the virtual synchronous generator, T e is the virtual synchronous generator and electromagnetic torque, D p is the damping coefficient of the virtual synchronous generator, J is the inertia coefficient of the virtual synchronous generator, θ is the power angle; the damping coefficient D p The introduction of the inertia coefficient J enables the model to provide damping and inertia during the transition process, reduce frequency oscillations, and improve the dynamic stability of the system by suppressing the rapid change of stored energy.

[0102] The reactive power calculation formula of virtual synchronous generator is:

[0103]

[0104] Where: e q is the q-axis modulation voltage of the virtual synchronous generator, reflecting the regulation effect of the power electronic equipment on the system node voltage; K a is the voltage gain coefficient, V set is the set value of the node voltage, U0 is the actual voltage value of the current node, and reactive power regulation is achieved through Q set and Q expression, where Q set is the set reactive power value, Q is the actual reactive power value, n q The model combines the dynamic relationship between node voltage and reactive power, and can effectively reflect the role of power electronic equipment in power flow regulation.

[0105] Step 1.2) Based on the electrical and control characteristics of multiple types of converters in power electronic equipment (such as static VAR compensator SVC, static synchronous compensator STATCOM, flexible AC transmission system FACTS and inverter, etc.), a power flow calculation model is constructed.

[0106] Specifically, a power flow calculation model with multiple optimization objectives is established, which can be expressed as:

[0107] F min =(f1(x,u),f2(x,u),f3(x,u),f4(x,u)…,fn (x,u)),u=[u1,u2,…,u D ]

[0108] The constraints are:

[0109] G i (x,u)≥0,i=1,2

[0110] H i (x,u)=0,i=1,2

[0111] Where: F min is the total set of optimization targets, f1(x,u) is optimization target 1, f2(x,u) is optimization target 2, and f n (x,u) is the optimization target n, x is the state variable. In this embodiment, the state variables include the voltage of each node in the distribution network, the initial load of each node, and the power and impedance of each branch. u is the control variable. In this embodiment, the control variable is determined according to the decision of the optimization subject (such as power plant, distribution network, operator, etc.), D is the dimension of the control variable, and G i (x,u) is the inequality constraint set of the i-th optimization objective, H i (x,u) is the set of equality constraints for the i-th optimization objective;

[0112] Among them, as attached Figure 2 As shown, the active power and reactive power of power electronic equipment satisfy the following relationship:

[0113]

[0114] Where: U i is the voltage of the sending node i, is the voltage vector of the sending node i, U j is the voltage at the receiving node j, is the voltage vector of receiving node j, is the conjugate of the voltage at the receiving node j; R ij is the resistance of the branch between the sending node i and the receiving node j, X ij is the reactance of the branch between the sending node i and the receiving node j; P j is the active power of receiving node j, Q j is the reactive power of receiving node j;

[0115] To ensure the existence of a feasible power flow solution for the distribution network, we have

[0116]

[0117] Therefore, the static voltage stability index of the receiving node j can be defined as:

[0118]

[0119] The steady-state operation of the receiving node j must satisfy the following formula:

[0120]

[0121] use The size of is used to determine the static voltage stability level of the distribution network. The smaller it is, the lower the static voltage stability level of the distribution network. The node with the smallest static voltage stability index in the distribution network is also the node that is most likely to experience voltage collapse.

[0122] Specifically, the set of equality constraints for each optimization objective includes:

[0123]

[0124] Where: P j is the active power of the jth receiving node, P j+1 is the active power of the j+1th receiving node, P L(j+1) is the active power of the distributed energy storage connected to the j+1th receiving node, R j,j+1 is the impedance between the jth receiving node and the j+1th receiving node, Q j is the reactive power of the jth receiving node, X k,k+1 is the reactance between the jth receiving node and the j+1th receiving node, V j is the voltage per unit value of the jth receiving node.

[0125] Step 1.3) Use the power flow calculation model to monitor and analyze the operation status of the distribution network in real time. Specifically, the operation status of the distribution network is analyzed in real time through the line crossing monitoring module to monitor whether key parameters such as node voltage, line current and power flow exceed the preset safety thresholds, such as whether the node voltage exceeds the upper and lower limits, whether the line current exceeds the rated capacity, whether the power flow is unbalanced, etc. Once a line crossing is detected, the system will record the line crossing type (such as voltage crossing, current crossing or power crossing), line crossing location (node ​​number or line number), line crossing value (actual voltage, current or power value) and the timestamp of the line crossing.

[0126] Step 2) Measure the status data information of power electronic equipment in different areas of the distribution network, and determine the fault status of the power electronic equipment and whether it is necessary to issue auxiliary service instructions to the power electronic equipment based on the status data information of each power electronic equipment. Specifically, measure the voltage and current of power electronic facilities such as distributed power sources or charging piles in different geographical locations of the distribution network, including amplitude frequency, phase, sampling frequency, and time interval for uploading data.

[0127] Specifically, step 2) includes the following steps:

[0128] Step 2.1) The local servers in each area continuously sample the status data information of the power electronic equipment in the corresponding area for a set period of time to obtain the sampling value, and obtain the current time as the time tag of the sampling value, and upload the sampling value and time tag to the cloud; specifically, the cloud sends a sampling signal, and after the local servers in each area receive the sampling signal, they start to continuously sample the status data information of the power electronic equipment in the corresponding area for a period of T to obtain the sampling value, and obtain the current time as the time tag. After the sampling time T ends, the data is uploaded to the cloud, and the cloud retains the data with the same sampling time. Figure 3 shown.

[0129] When the set of power electronic devices to be sampled is D, we have

[0130] D=[D1,D2,D3,D4,...D i ...]

[0131] Where D is the set of power electronic devices to be sampled, D i It is the status data information of specific power electronic equipment, such as voltage V, current I, active power P, reactive power Q, and line crossing of power electronic equipment such as distributed power supply or charging pile.

[0132] The sampling results of each power electronic device within T time are:

[0133]

[0134] in, D i Power electronics in t ii The sampling value at the time, D T for A collection of .

[0135] Step 2.2) The cloud selects the valid sampling value sequence of each power electronic device based on the sampling values ​​sent by the local servers in each region and the time tags.

[0136] When the cloud filters out j At time , when each power electronic device has a corresponding sampling value, the effective sampling value sequence is:

[0137]

[0138] When the cloud cannot filter out all power electronic devices with sampling values, j At time t, find the time t when each power electronic device has the most sampling values f , and the rest at time tf Power electronic equipment without sampling value is f Find the effective time around the time. If the power electronic equipment D i No f time, and t ii satisfy:

[0139] |t f -t ii |≤ε

[0140] Among them, ε is the effective threshold, which means that it will not affect the effectiveness of the program flow. ii Sampling value at time Add to the effective value sampling value sequence;

[0141] At this time, the effective sampling value sequence of each power electronic device is:

[0142]

[0143] Step 2.3) After obtaining the valid sampling value sequence of the power electronic equipment in each area, the power flow calculation of each power electronic equipment is performed according to step 1), and it is determined whether to send auxiliary service instructions to the power electronic equipment in each area according to the power flow calculation results.

[0144] After obtaining the valid sampling value sequence of each power electronic device, the power flow calculation of each power electronic device is performed according to step 1) to obtain:

[0145]

[0146] in, is the effective sampling value of the i-th power electronic device after power flow calculation;

[0147] The safety threshold of each power electronic device is set as:

[0148]

[0149] in, is the safety threshold corresponding to the i-th power electronic device;

[0150] if The elements in D are greater than s The elements in can get the following control sequence:

[0151]

[0152] in, The execution logic meets the following process:

[0153] when hour, is True, indicating that the i-th power electronic device requires an auxiliary service instruction;

[0154] when hour, is False, indicating that the i-th power electronic device does not require an auxiliary service instruction.

[0155] Step 3) After the fault status of each power electronic device is obtained in step 2), the inverter is controlled according to the setting method.

[0156] The setting method in step 3) includes the following steps:

[0157] Step 3.1) Obtain the three-phase voltage V on the inverter side abc , obtain the three-phase voltage U on the distribution network side through communication abc And the three-phase current I abc , and perform coordinate transformation on these electrical signals;

[0158] Step 3.2) Calculate the phase angle on the inverter side and the phase angle on the distribution network side according to the converted three-phase voltage on the inverter side, the three-phase voltage on the distribution network side, and the three-phase current on the distribution network side.

[0159] The converted three-phase voltage on the inverter side, the three-phase voltage on the distribution network side, and the three-phase current on the distribution network side are input into the phase-locked loop module to calculate the phase angle on the inverter side and the phase angle on the distribution network side;

[0160] As attached Figure 4 As shown, the phase-locked loop includes a PI controller and an integral operation module. The input of the phase-locked loop module is the q-axis voltage V on the inverter side. q and the q-axis voltage U on the distribution network side q , the phases of the inverter side and the distribution network side are tracked through the PI controller;

[0161] Among them, the output equation of the PI controller is:

[0162]

[0163] Where: PI v is the inverter side output, K pv is the proportional gain of the PI controller, K iv is the integral gain, K p is the scale parameter, K i is the integral parameter, PI u Output from the distribution network side;

[0164] The phase angle θ on the inverter side is obtained by integrating the module and taking the remainder. v and the phase angle θ on the distribution network sideu :

[0165]

[0166] Step 3.3) Calculate the power angle difference and the phase compensation angle based on the phase angle on the inverter side and the phase angle on the distribution network side.

[0167] The power angle calculation and compensation module is used to adjust the power angle through the fuzzy PID controller and output the phase compensation angle δ. The calculation formula of δ is:

[0168]

[0169] e δ =δ ref -(θ v -θ u )

[0170]

[0171] Where: ref is the phase angle reference value, e δ is the power angle error, Δe δ is the rate of change of the power angle error, ∫e δ dt is the integral of the power angle error, μ i is the membership degree of the corresponding fuzzy rule, δ i is the output of the corresponding fuzzy rule.

[0172] The input variable e of the membership function of the fuzzy PID controller δ , Δe δ , ∫e δ dt defines the language variables (NB, NM, NS, ZE, PS, PM, PB). The input variables are fuzzified using triangular membership functions, and the expression is:

[0173]

[0174] Definition of fuzzy rules for fuzzy PID controller The control signal output of power angle compensation δ i , and its output rules are shown in the following table:

[0175]

[0176]

[0177] After the output is based on the fuzzy rules, the weighted average method is used to transform the fuzzy results into clear outputs:

[0178]

[0179] Where: μi and δ i are both intermediate variables in fuzzy control, μ i is the membership degree of the corresponding fuzzy rule, δ i is the output of the corresponding fuzzy rule, that is, the phase compensation angle before defuzzification.

[0180] Step 3.4) The power angle is adjusted according to the calculated phase compensation angle to generate the inverter control signal to achieve precise control of the inverter. After the normal operation of the power system is restored, the system normal signal is sent to the power dispatching center.

[0181] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit the technical solution. Those skilled in the art should understand that those modifications or equivalent substitutions of the technical solution of the present invention that do not depart from the purpose and scope of the technical solution should be included in the scope of the claims of the present invention.

Claims

1. A method for emergency stability control of a smart distribution network based on a communication architecture of a time tag, characterized in that: The following steps are involved: Step 1) constructing a power flow calculation model including dynamic characteristics of power electronic equipment; Step 2) measuring the status data information of power electronic devices in different areas of the distribution network, and determining the fault status of the power electronic devices according to the status data information of each power electronic device, and whether an auxiliary service instruction needs to be issued to the power electronic devices; Step 3) After the fault status of each power electronic device is obtained in step 2), the inverter is controlled according to the setting method.

2. According to claim 1, the method for emergency stability control of a smart distribution network based on a communication architecture of a time tag is characterized in that: Step 1) includes the following steps: Step 1.1) Establish a dynamic characteristic model of power electronic equipment in power flow calculation; Step 1.2) construct a power flow calculation model based on the electrical characteristics and control characteristics of multiple types of converters in power electronic equipment; Step 1.3) Use the power flow calculation model to monitor and analyze the operating status of the distribution network in real time.

3. The method for emergency stability control of a smart distribution network based on a communication architecture of a time tag according to claim 1, characterized in that: Step 2) includes the following steps: Step 2.1) The local server in each area continuously samples the status data information of the power electronic equipment in the corresponding area at the set time to obtain a sampled value, and obtains the current time as the time tag of the sampled value, and uploads the sampled value and the time tag to the cloud; Step 2.2) The cloud selects the valid sampling value sequence of each power electronic device based on the sampling values ​​sent by the local servers in each region and the time tags; Step 2.3) After obtaining the valid sampling value sequence of the power electronic equipment in each area, the power flow calculation of each power electronic equipment is performed according to step 1), and it is determined whether to send auxiliary service instructions to the power electronic equipment in each area according to the power flow calculation results.

4. The method for emergency stability control of a smart distribution network based on a communication architecture of a time tag according to claim 1, characterized in that: The setting method in step 3) includes the following steps: Step 3.1) Obtain the three-phase voltage V on the inverter side abc , obtain the three-phase voltage U on the distribution network side through communication abc And the three-phase current I abc , and perform coordinate transformation on these electrical signals; Step 3.2) Calculate the phase angle on the inverter side and the phase angle on the distribution network side according to the converted three-phase voltage on the inverter side, the three-phase voltage on the distribution network side, and the three-phase current on the distribution network side; Step 3.3) Calculate the power angle difference and the phase compensation angle according to the phase angle on the inverter side and the phase angle on the distribution network side; Step 3.4) The power angle is adjusted according to the calculated phase compensation angle to generate an inverter control signal.

5. The method for emergency stability control of a smart distribution network based on a communication architecture of a time tag according to claim 3 is characterized in that: In step 2.1), when the set of power electronic devices to be sampled is D, we have <h2 style=";text-align:left;direction:ltr">D=[D1,D2,D3,D4,...D<h2 style=";text-align:left;direction:ltr"> i <h2 style=";text-align:left;direction:ltr"> ...] Where D is the set of power electronic devices to be sampled, D i It is the status data information of specific power electronic equipment; The sampling results of each power electronic device within T time are: in, D i Power electronic equipment in t ii The sampling value at the time, D T for A collection of .

6. The method for emergency stability control of a smart distribution network based on a communication architecture of a time tag according to claim 5 is characterized in that: Step 2.2) When the cloud filters out j At time , when each power electronic device has a corresponding sampling value, the effective sampling value sequence is: When the cloud cannot filter out all power electronic devices with sampling values, j At time t, find the time t when each power electronic device has the most sampling values f , and the rest at time t f Power electronic equipment without sampling value is f Find the effective time around the time. If the power electronic equipment D i No f time, and t ii satisfy: |t f -t ii |≤ε Among them, ε is the effective threshold, then the power electronic device is ii Sampling value at time Add to the effective value sampling value sequence; At this time, the effective sampling value sequence of each power electronic device is:

7. The method for emergency stability control of a smart distribution network based on a communication architecture of a time tag according to claim 6 is characterized in that: In step 2.3), after obtaining the valid sampling value sequence of each power electronic device, the power flow calculation of each power electronic device is performed according to step 1) to obtain: in, is the effective sampling value of the i-th power electronic device after power flow calculation; The safety threshold of each power electronic device is set as: in, is the safety threshold corresponding to the i-th power electronic device; if The elements in D are greater than s The elements in can get the following control sequence: in, The execution logic meets the following process: when hour, is True, which means that the i-th power electronic device requires an auxiliary service instruction; when hour, is False, which means that the i-th power electronic device does not require an auxiliary service instruction.

8. The method for emergency stability control of a smart distribution network based on a communication architecture of a time tag according to claim 4 is characterized in that: In step 3.2), the converted three-phase voltage on the inverter side, the three-phase voltage on the distribution network side, and the three-phase current on the distribution network side are input into the phase-locked loop module to calculate the phase angle on the inverter side and the phase angle on the distribution network side; The phase-locked loop module includes a PI controller and an integral operation module. The PI controller adjusts the phase of the input voltage, and then inputs the adjusted voltage into the integral operation module to obtain the phase angle θ on the inverter side. v and the phase angle θ on the grid side u .

9. The method for emergency stability control of a smart distribution network based on a communication architecture of a time tag according to claim 8, characterized in that: In step 3.3), the fuzzy PID controller is used to calculate the phase compensation angle δ of the power angle. The calculation formula of δ is: e δ =d ref -(θ v -θ u ) Where: ref is the phase angle reference value, e δ is the power angle error, Δe δ is the rate of change of the power angle error, δe δ dt is the integral of the power angle error, μ i is the membership degree of the corresponding fuzzy rule, δ i is the output of the corresponding fuzzy rule.

10. The method for emergency stability control of a smart distribution network based on a communication architecture of a time tag according to claim 2, characterized in that: In step 1.2), a power flow calculation model with multiple optimization objectives is established, which is expressed as: F min =(f1(x,u),f2(x,u),f3(x,u),f4(x,u)…,f n (x,u)),u=[u1,u2,…,u D ] The constraints are: G i (x,u)≥0,i=1,2 H i (x,u)=0,i=1,2 Where: F min is the total set of optimization targets, f1(x,u) is optimization target 1, f2(x,u) is optimization target 2, and f n (x,u) is the optimization target n, x is the state variable, u is the control variable, D is the dimension of the control variable, G i (x,u) is the inequality constraint set of the i-th optimization objective, H i (x,u) is the set of equality constraints for the i-th optimization objective; Among them, the active power and reactive power of power electronic equipment satisfy the following relationship: Where: U i is the voltage of the sending node i, is the voltage vector of the sending node i, U j is the voltage at the receiving node j, is the voltage vector of receiving node j, is the conjugate of the voltage at the receiving node j; R ij is the resistance of the branch between the sending node i and the receiving node j, X ij is the reactance of the branch between the sending node i and the receiving node j; P j is the active power of receiving node j, Q j is the reactive power of receiving node j; To ensure the existence of a feasible power flow solution for the distribution network, we have Therefore, the static voltage stability index of the receiving node j can be defined as: The steady-state operation of the receiving node j must satisfy the following formula: Specifically, the set of equality constraints for each optimization objective includes: Where: nbus is the number of nodes in the distribution network, P j is the active power of the jth receiving node, P j+1 is the active power of the j+1th receiving node, P L(j+1) is the active power of the distributed energy storage connected to the j+1th receiving node, R j,j+1 is the impedance between the jth receiving node and the j+1th receiving node, Q j is the reactive power of the jth receiving node, X k,k+1 is the reactance between the jth receiving node and the j+1th receiving node, V j is the voltage per unit value of the jth receiving node.

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