Movable energy storage and electric energy quality comprehensive treatment device and method thereof

Abstract

The invention discloses a movable energy storage and electric energy quality comprehensive treatment device and method, and relates to the technical field of electric power systems, the movable energy storage device comprises an energy type energy storage system and a power type energy storage system, and the movable energy storage device has bidirectional charging and discharging capability; the electric energy quality comprehensive treatment device is connected with an intelligent electric energy meter of a user and the movable energy storage device, systematic application is achieved through effective combination of the movable energy storage device and the electric energy quality comprehensive treatment device, and therefore electric energy quality in remote areas is effectively improved; according to the invention, protection of electric equipment can be facilitated, power supply pressure of lines / transformer areas can be reduced, loss of electric energy in a transmission process can be effectively reduced, load balance in three-phase lines can be ensured, utilization rate of electric power assets can be improved, energy cost can be saved, energy-saving, environment-friendly and safe development concepts can be realized, and user satisfaction can be greatly improved.

Description

Technical Field

[0001] The present invention relates to the technical field of electric power systems, and in particular to a portable energy storage and power quality comprehensive management device and a method thereof. Background Art

[0002] With the development of economy, the living standard of urban and rural residents is constantly improving, and the electricity load of people's production and life is also steadily increasing year by year; people's requirements for electricity dependence, power supply quality, power supply reliability, etc. are also constantly increasing. As the terminal carrier of power transmission and distribution, the distribution network carries important power transmission and distribution work. Therefore, the stability, power quality and power supply reliability of the distribution network system will be the most intuitive experience of power grid users.

[0003] The distribution network is widely used in daily life. According to the actual application, the distribution network is divided into urban distribution network and remote distribution network. Since the economic benefits brought by the distribution network in remote areas are relatively poor, the stability of the distribution network in remote areas is relatively weak, so it is necessary to strengthen the research efforts to improve the stability of the distribution network in remote areas. In the low-voltage distribution substation in remote areas, the biggest limiting factor of the entire substation is the low quality of the output power in the system. The output quality of the entire power supply is very poor, and the voltage is relatively unstable, which can easily cause material losses to local residents. Another factor is that the distribution system may also have unreasonable single-phase load during the power supply process, which may cause three-phase imbalance in the entire low-voltage distribution substation. This phenomenon may cause huge uncertainty in electricity consumption and greatly reduce the power factor of the distribution substation. In addition, in the low-voltage distribution substation throughout the year, there are generally low voltage quality, three-phase imbalance and low power factor at the end of the power supply radius. With the continuous improvement of the level of urban and rural electrification, the problems of high load pressure on the power grid and aging of the lines that cannot be transformed in time have gradually become prominent.

[0004] Traditional means of improving low voltage, such as expanding transformer capacity or installing reactive power compensation devices, have the defect of low asset utilization. At present, the common solutions to the low voltage problem in the terminal area of ​​rural power grid include reducing the power supply radius, increasing the conductor cross-section, installing reactive power compensation equipment, and increasing the number of substations, but the above methods often have problems such as long construction period, low investment benefits, and low asset utilization; in addition, due to environmental conditions, it is extremely difficult to increase the number of substations or increase the interval between outgoing lines. Therefore, the end of the distribution network urgently needs flexible power sources to optimize power flow distribution and improve voltage quality.

[0005] Moreover, in the current design process of the entire low-voltage distribution area, the fixed energy storage system can improve the transmission and distribution quality of the low-voltage distribution area, which mainly includes load transfer, grid fluctuation and peak shaving. In addition, the fixed energy storage system can improve the voltage quality by providing reactive power to the grid. However, with the surge in the number of distributed renewable energy sources, the traditional fixed energy storage system has great limitations in application scenarios.

[0006] Therefore, it is necessary to design a portable energy storage and power quality comprehensive management device and method to solve the above technical problems. Summary of the invention

[0007] In response to the above problems, the present application provides a portable energy storage and comprehensive power quality management device and a method thereof. Through the effective combination of the portable energy storage device and the comprehensive power quality management device, a systematic application is formed, thereby achieving effective improvement of power quality in remote areas, which can be beneficial to the protection of electrical equipment, reduce the power supply pressure of lines / substations, effectively reduce the loss of electric energy during transmission, ensure load balance in three-phase lines, improve the utilization rate of power assets and save energy costs, realize the development concept of energy saving, environmental protection, and safety, and greatly improve user satisfaction.

[0008] To achieve the above object, the present invention provides the following technical solution: a mobile energy storage and power quality comprehensive management device, comprising:

[0009] Mobile energy storage devices, including energy storage systems and power storage systems, are used to store and release electrical energy, and the mobile energy storage devices have bidirectional charging and discharging capabilities, and the mobile energy storage devices can be flexibly dispatched according to power quality management requirements; and

[0010] The comprehensive power quality management device is connected to the user's smart power meter and the movable energy storage device.

[0011] Further, preferably, the power quality comprehensive management device comprises:

[0012] Power quality detection module, which is used to collect and analyze power consumption data in remote areas, identify power quality problems, extract features, and classify disturbance signals;

[0013] An energy storage capacity configuration module, including a capacity configuration model constructed according to components in the power distribution system, for optimizing the configuration of the energy storage capacity of the mobile energy storage device;

[0014] An optimization control strategy module is used to formulate a control strategy for the mobile energy storage device based on the source-grid coordination concept and the constraints of the capacity configuration model operation layer, and in combination with the charging and discharging characteristics and the spatiotemporal coupling characteristics of the mobile energy storage device, so as to improve the power quality; and

[0015] The monitoring and early warning system includes an intelligent monitoring system for real-time monitoring of the power quality and the operating status of the movable energy storage device, and providing early warning and alarm functions.

[0016] Furthermore, preferably, the movable energy storage devices all use lithium iron phosphate battery packs, charging equipment and discharging equipment connected to the lithium iron phosphate battery packs as energy storage battery systems, and the energy storage battery systems perform bidirectional energy conversion with the user power grid through energy storage inverters and isolation transformers in turn, and the energy storage inverters are connected to voltage sampling modules and current sampling modules, and the voltage sampling modules and the current sampling modules are connected to the upper power grid, and the energy storage inverters and the energy storage battery systems are connected to the intelligent monitoring system, and the intelligent monitoring system is communicatively connected to the remote platform.

[0017] Further, preferably, the intelligent monitoring system comprises:

[0018] A charging control module, installed in the charging device;

[0019] A voltage, current and temperature detection module connected to the lithium iron phosphate battery pack;

[0020] a discharge control module, installed in the discharge device; and

[0021] The main control chip is connected to the charging control module, the voltage, current and temperature detection module and the discharge control module, and is used to upload the working status and detection data of the charging control module, the voltage, current and temperature detection module and the discharge control module to the main control chip for unified management and control by the main control chip.

[0022] Further, as a preference, the remote platform includes a computer, a main control board is installed inside the computer, and the main control board is communicatively connected with the communication module and the main control chip in sequence, and the computer is used for remote monitoring of voltage data, data transmission and system control functions.

[0023] Further, preferably, the power quality detection module includes a data acquisition unit, a signal processing unit and a classification and identification unit, the data detected by the data acquisition unit includes power quality detection, flow information detection and equipment operating condition detection, and the signal processing unit and the classification and identification unit are used to realize the extraction, classification and identification of power quality disturbances.

[0024] Further, preferably, the power quality detection module is respectively connected to each line of the user's power grid, and the power quality detection module is connected to the energy management software, the energy management software is connected to the power conversion module, the power conversion module is connected to the hybrid energy storage unit, and the hybrid energy storage unit is connected to the energy management software.

[0025] Further, as a preference, the power conversion module includes a VSC inverter, one end of which is connected to the user power grid line by a filter circuit, the number of the VSC inverters is twice the number of the user power grid lines, and the other end of each of the VSC inverters is connected to a common DC bus, the energy-type energy storage system is connected to the common DC bus through the VSC inverter, the power-type energy storage system is also connected to the common DC bus through the VSC inverter, and the energy-type energy storage system, the VSC inverter connected to the energy-type energy storage system, the power-type energy storage system and the VSC inverter connected to the power-type energy storage system together constitute the hybrid energy storage unit.

[0026] Furthermore, preferably, the energy storage capacity configuration module adopts a multi-objective optimization algorithm to optimize the configuration of the energy storage capacity.

[0027] A method for managing a mobile energy storage and power quality comprehensive management device, comprising the following steps:

[0028] S1. First determine the installation location of the mobile energy storage device and connect it to the user's smart energy meter, collect and monitor the three-phase current value of the installation location of the mobile energy storage device, calculate the average value of the lowest voltage of the low-voltage user, analyze the power quality problem, extract features, and classify the disturbance signal;

[0029] S2. Construct a capacity configuration model of a mobile energy storage device according to various components existing in the distribution network system;

[0030] S3. Based on the source-grid coordination concept and the constraints of the capacity configuration model operation layer, combined with the charging and discharging characteristics and spatiotemporal coupling characteristics of the mobile energy storage device, formulate the control strategy of the mobile energy storage device, determine the installation capacity of the mobile energy storage device and optimize the energy storage time of the comprehensive power quality management device;

[0031] S4. According to the user's minimum voltage value, a target voltage value is set;

[0032] S5. The monitoring and early warning system monitors the power quality and the operating status of the mobile energy storage device in real time, and provides early warning and alarm functions;

[0033] S5. According to the monitoring results and warning information, when all user voltages are qualified, the process ends; when the user voltage is unqualified, return to S4.

[0034] Compared with the prior art, the present invention provides a mobile energy storage and power quality comprehensive management device and method thereof, which has the following beneficial effects:

[0035] 1. The present invention can achieve systematic application through the effective combination of a movable energy storage device and a comprehensive power quality management device, thereby realizing effective improvement of power quality in remote areas, which can be beneficial to the protection of electrical equipment, reduce the power supply pressure of lines / substations, effectively reduce the loss of electric energy in the transmission process, ensure the load balance in three-phase lines, improve the utilization rate of power assets and save energy costs, realize the development concept of energy saving, environmental protection and safety, and greatly improve user satisfaction.

[0036] 2. The present invention utilizes the characteristics of movable energy storage devices that can provide active and reactive power, realizes voltage regulation of rural power grids, improves power quality on the user side, and reduces line losses in distribution networks. In addition, “low storage and high generation” can effectively alleviate the tight power supply situation while realizing energy arbitrage, and can bring extensive social and economic benefits to the operation of rural power grids in remote areas.

[0037] 3. The present invention configures a movable energy storage device at the terminal station of the distribution network, which can effectively improve the power supply quality of the low-voltage station, optimize the power flow distribution by utilizing the energy storage charging and discharging characteristics, improve the load rate of the heavily overloaded line, thereby delaying the expansion and reconstruction of the line, reducing the power supply company's investment in the construction of the agricultural low-voltage distribution network, and realizing the benefits of power asset substitution. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] The accompanying drawings are used to provide a further understanding of the present application and constitute a part of the specification. Together with the embodiments of the present application, they are used to explain the present application and do not constitute a limitation to the present application.

[0039] Figure 1 A schematic diagram of the topological structure of integrated power quality management in remote areas of a mobile energy storage and integrated power quality management device;

[0040] Figure 2 A schematic diagram of the structure of a remote area integrated power quality management system of a mobile energy storage and power quality integrated management device;

[0041] Figure 3 A schematic diagram of a mobile energy storage device in a mobile energy storage and power quality comprehensive management device being connected to the grid;

[0042] Figure 4It is a schematic diagram of the overall framework of a movable energy storage device in a movable energy storage and power quality comprehensive management device;

[0043] Figure 5 A flowchart diagram of targeted management measures and solutions for a mobile energy storage and power quality comprehensive management device; DETAILED DESCRIPTION

[0044] In order to make the purpose, technical solutions and advantages of this application clearer, the technical solutions in this application will be clearly and completely described below in conjunction with the drawings in this application. Obviously, the described embodiments are part of the embodiments of this application, not all of them. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0045] The terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features; in the description of this application, unless otherwise specified, "plurality" means two or more.

[0046] See also Figure 1-Figure 5 The embodiment of the present invention provides a mobile energy storage and power quality comprehensive management device, which includes:

[0047] Mobile energy storage devices, including energy storage systems and power storage systems, are used to store and release electrical energy, and the mobile energy storage devices have bidirectional charging and discharging capabilities, and the mobile energy storage devices can be flexibly dispatched according to power quality management requirements; and

[0048] The comprehensive power quality management device is connected to the user's smart power meter and the movable energy storage device.

[0049] It needs to be explained that power quality problems are generally divided into two categories: steady-state and dynamic. Steady-state power quality problems generally include frequency deviation, voltage deviation, harmonics, three-phase imbalance, etc., and dynamic power quality problems generally include voltage fluctuation, voltage sag, etc., and the actual power grid may be a combination of the above-mentioned problems, which are generally called comprehensive power quality problems. The comprehensive power quality management device can collect data by installing smart meters on the user side, and modify the smart meters to add the "voltage qualification rate and power supply reliability rate" collection function. Combined with the user's electricity consumption information collection system, it can monitor the "voltage qualification rate and power supply reliability rate" of all power supply users, and realize the statistical analysis of the power supply reliability rate and voltage qualification rate of all-caliber clients.

[0050] Based on the above technical solutions, the configuration of mobile energy storage devices is limited by the investment and construction costs and the actual technical level. When selecting the energy storage configuration solution, relevant constraints need to be considered, including the rated power and capacity constraints of the energy storage configuration:

[0051] P ESS,min ≤P ESS ≤P ESS,max

[0052] E ESS,min ≤E ESS ≤E ESS,max

[0053] Where P ESS , P ESS,min , P ESS,max E are the rated power of the mobile energy storage device configured in the system and the lower and upper limits of the rated power; ESS , E ESS,min , E ESS,max They are respectively the capacity of the movable energy storage device configured for the system and the lower and upper limits of the capacity.

[0054] Installation quantity limit of mobile energy storage:

[0055] n ins ≤n max

[0056] Where n ins is the actual number of installed mobile energy storage devices; n max The maximum number of movable energy storage devices that can be installed.

[0057] Based on the energy storage operation characteristics, the charging and discharging rules and related constraints of energy storage are analyzed. The energy storage capacity E(t+1) depends on the energy storage capacity E(t) at the previous moment and the charging or discharging power P(t) of the energy storage at each moment:

[0058] When the mobile energy storage is in the charging process (P ch，i (t)<0):

[0059] E(t+1)=E(t)-η c ·P ch，i ·Δt

[0060] When the mobile energy storage is in the charging process (P dis，i (t)>0):

[0061]

[0062] Where, t = 1, 2, ..., T (T = 24); i represents the i-th movable energy storage; P ch,i(t) is the charging power of the energy storage at time t; P dis,i (t) is the discharge power of the energy storage at time t; η c is the charging efficiency; η d is the discharge efficiency; Δt is the time interval.

[0063] Energy storage charging / discharging power:

[0064] P ch,i (t)≤P ch,max

[0065] P dis,i (t)≤P dis,max

[0066] Where P ch,i (t) and P ch,max are energy storage charging power and maximum charging power respectively; P dis,i (t) and P dis,max They are the energy storage discharge power and the maximum discharge power respectively; in addition, the energy storage cannot work in the charging and discharging states at the same time.

[0067] State of charge of energy storage:

[0068]

[0069] Because the dispatch of the power grid is cyclical, it is stipulated that the charge state (stored electricity) of the energy storage at the initial and final time of the dispatch is the same:

[0070] SOC i (T) = SOC i (0)

[0071] In the formula, SOC i (0) and SOC i (T) represents the charge state of the i-th mobile energy storage at the initial and end times of scheduling, respectively.

[0072] The life of energy storage is closely related to the working mode of energy storage. Other constraints that need to be considered include the charge and discharge depth of energy storage (i.e. the upper and lower limits of the SOC of energy storage), the number of charge and discharge times of energy storage within a certain period of time, etc.

[0073] Energy storage state of charge constraints:

[0074] SOC min ≤SOC i (t)≤SOC max

[0075] In the formula, SOC min and SOC maxIt is the minimum and maximum value of the state of charge. The minimum value is generally between 10% and 30%, and the maximum value is generally between 80% and 100%.

[0076] The total number of charge and discharge cycles in the entire life cycle of the energy storage is a constant. In order to prevent frequent charge and discharge of energy storage from accelerating the attenuation of energy storage life, the number of charge and discharge cycles of energy storage in the scheduling period will be constrained according to actual conditions:

[0077] n cyc ≤n cyc，max

[0078] Where n cyc and n cyc,max They are respectively the number of charge and discharge times of energy storage within a scheduling cycle and the maximum number of charge and discharge cycles allowed within a scheduling cycle.

[0079] In view of the special properties of the mobile energy storage device, it is also necessary to mathematically describe the mobility of the device and construct a linear model based on the time-varying decomposition matrix to describe the operating characteristics of the mobile energy storage.

[0080] Assuming that in the scheduling period, the mobile energy storage is transferred from one access point to another access point, and its access point is located at the coupling position of the power grid and the transportation network. First, the time matrix H is established to describe the transmission time required between each mobile energy storage access point under the consideration of traffic road congestion:

[0081]

[0082] In the formula, h ijk It represents the normalized transmission time from access point i to access point j if the mobile energy storage starts at time k.

[0083] Secondly, a time-varying decomposition matrix T is established to include all transmission conditions of mobile energy storage:

[0084]

[0085] Where: I and O are the unit matrix and zero matrix of size S×S respectively; S is the maximum number of access points of mobile energy storage; represents the full action matrix with a transmission time of Δh at time k, whose diagonal elements are zero and is defined as follows:

[0086]

[0087]

[0088] Where R represents the maximum transmission time in the time matrix; f ijk (Δt) is the prediction element in the full action matrix, when Δt>h ijk, indicating that Δt exceeds the prediction range, that is, exceeds the actual transmission time of the mobile energy storage from access point i to access point j at time k. The mobile energy storage will no longer perform transmission actions in the subsequent period, so the prediction element is 0. When Δt≤h ijk , the predicted elements will all be 1, indicating that the full action matrix retains all the transmission conditions of the mobile energy storage during the scheduling period. Then, the time-varying decomposition matrix T is combined with the mobile energy storage position flag matrix Z to limit the actual transmission conditions of the mobile energy storage.

[0089]

[0090] Where: U is a unit column vector of size S(K-1); the position flag matrix Z contains the position status of each access point of the mobile energy storage in each time period, and the element z ik is a binary variable. When the element value is 1, the mobile energy storage is located at access point i at time period k.

[0091] Furthermore, in order to improve the description of the mobile energy storage transmission action, the mobile flag c is added ijk and pre-action flag y sk :

[0092]

[0093] Δh ijk ∈{1,2,...,h ijk},c ijk ≤z ik

[0094]

[0095] Δh ijk ∈{1,2,...,h ijk},y sk =z s(k+1) -z sk

[0096]

[0097] Among them, the mobile flag c ijk is a binary variable, indicating whether the mobile energy storage is ready to be transmitted from access point i to access point j at time k. When the mobile flag is 1, it means that the mobile energy storage is ready to act; the pre-action flag y sk is an integer variable, which indicates the preparation action of the mobile energy storage at access point s at time k in the next period. When its value is -1, it means that the mobile energy storage is ready to leave access point s. When its value is 0, it means that the mobile energy storage is in the transmission state or stays at access point s. When its value is 1, it means that the mobile energy storage will arrive at access point s at the next moment.

[0098] In order to prevent the mobile energy storage from being transmitted on the spot, the pre-action flag y sk After absolute value processing, a new flag bit a is generated s :

[0099]

[0100] Where: a s Indicates the absolute value of the corresponding pre-action flag. ik = -1, |a1-a2-…-a S-1 | indicates the action state corresponding to the transmission of mobile energy storage from access point i to other access points, among which there must be a flag bit a s The value of y is 1; ik =1 or y ik = 0, it means that the mobile energy storage is about to arrive at the access point i, the mobile energy storage is in the transmission state or waiting at the original location. s There is no restriction. Figure 3 and Table 1 show an example of the transmission process of a mobile energy storage vehicle and the value of each flag bit, respectively.

[0101] The operating cost includes the cost of the distribution network purchasing electricity from the upper power grid (when the purchase amount is negative, it is considered to be selling electricity to the upper power grid), as well as the power generation costs of other generators in the distribution network. In order to maximize the utilization of renewable energy, renewable energy generation such as wind power and photovoltaic power generation is generally connected to the distribution network in the form of maximum power tracking and is regarded as an uncontrollable distributed power source, so its dispatching cost is not counted. At the same time, when formulating the charging and discharging strategy of energy storage, considering the total number of charging and discharging times during the life cycle of the energy storage, the dispatching model must meet the constraint of the number of charging and discharging times of the energy storage during the dispatching cycle, so the operating cost of the energy storage is not included in the dispatching cost. Accordingly, the economic goal is to minimize various comprehensive costs under the constraints of meeting the safety and stable operation of the system. The economic objective function is the average daily total cost of the distribution network f1, which is defined as:

[0102]

[0103] In the formula, f inv is the investment cost of energy storage; f ope is the system operation cost; C E is the price related to capacity; C P is the price related to power; n ESS N is the number of energy storage installations; y Plan the life of the system; r (t) is the upper grid electricity price; P up (t) is the amount of electricity purchased by the upper power grid; n DG is the amount of distributed renewable energy; C i(t) and P DG,i (t) is the output cost and active output of the i-th distributed generator in the t-th time period.

[0104] The volatility of renewable energy and load is an important factor affecting the safety and stability of the system. The configuration scheme of the mobile energy storage device is related to the power flow of the system and has a direct impact on the voltage quality. The voltage index is regulated by combining the charging and discharging rules of energy storage and reactive power optimization methods. The optimization objective function f2 for the voltage index is the average daily voltage deviation, which is defined as (the voltage deviation index is a comprehensive quantity rather than an actual quantity):

[0105]

[0106] Where N bus is the number of nodes; U i (t) is the voltage amplitude of the i-th node at time t; is the expected voltage amplitude of the i-th node; is the maximum allowable voltage deviation of the i-th node at time t.

[0107] When a year selects n day When calculating the objective function for a typical working day, the objective functions f1 and f2 need to be rewritten as:

[0108]

[0109] Where, d i is the number of days in a year that can be replaced by typical working day i; f1(i) is the average daily total cost of the i-th typical working day; f2(i) is an indicator related to the voltage deviation of the i-th typical working day.

[0110] On the basis of the above technical solutions, through the effective combination of mobile energy storage devices and comprehensive power quality management devices, a systematic application is achieved, thereby realizing the effective improvement of power quality in remote areas, which can be beneficial to the protection of electrical equipment, reduce the power supply pressure of lines / substations, effectively reduce the loss of electric energy in the transmission process, ensure the load balance in three-phase lines, improve the utilization rate of power assets and save energy costs, realize the development concept of energy saving, environmental protection and safety, and greatly improve user satisfaction.

[0111] In addition, the use of mobile energy storage devices can provide active and reactive power, realize voltage regulation of rural power grids, improve power quality on the user side, and reduce line losses in distribution networks. The "low storage and high generation" can effectively alleviate the tight power supply situation while realizing energy arbitrage, and can bring extensive social and economic benefits to the operation of rural power grids in remote areas.

[0112] In a possible implementation manner, the power quality comprehensive management device includes:

[0113] Power quality detection module, which is used to collect and analyze power consumption data in remote areas, identify power quality problems, extract features, and classify disturbance signals;

[0114] An energy storage capacity configuration module, including a capacity configuration model constructed according to components in the power distribution system, for optimizing the configuration of the energy storage capacity of the mobile energy storage device;

[0115] Optimizing the control strategy module, based on the source-grid coordination concept and the constraints of the capacity configuration model operation layer, such as the mobile energy storage operation characteristic model, the distributed power supply operation characteristic model, etc., and combining the charging and discharging characteristics and the time-space coupling characteristics of the mobile energy storage device, formulate the control strategy of the mobile energy storage device to improve the power quality; and

[0116] The monitoring and early warning system includes an intelligent monitoring system for real-time monitoring of the power quality and the operating status of the movable energy storage device, and providing early warning and alarm functions.

[0117] In a possible implementation, the movable energy storage device uses a lithium iron phosphate battery pack, a charging device and a discharging device connected to the lithium iron phosphate battery pack as an energy storage battery system, and the energy storage battery system performs bidirectional energy conversion with the user power grid through an energy storage inverter and an isolation transformer in turn, and the energy storage inverter is connected to a voltage sampling module and a current sampling module, and the voltage sampling module and the current sampling module are connected to a superior power grid, and the energy storage inverter and the energy storage battery system are connected to the intelligent monitoring system, and the intelligent monitoring system is communicatively connected to a remote platform.

[0118] It should be explained that since the mobile energy storage device for comprehensive power quality management in remote areas needs to be charged repeatedly, the requirements for the battery's cycle capacity are relatively high. Lithium-ion batteries are widely used in energy storage systems due to their superior performance. Among them, lithium iron phosphate batteries perform the best and can be charged repeatedly more than 2,000 times. In addition, the requirements for safety of mobile energy storage devices are relatively high. At the same time, lithium iron phosphate battery technology is relatively mature, and the operating temperature range is 20-75°C, which can meet the system temperature requirements, improve the safety of the energy storage system, and the cost is not high. It is very suitable for mobile energy storage devices. In summary, the energy storage battery system selects lithium iron phosphate battery packs, and needs to select a reasonable charging method based on the charging characteristics of lithium iron phosphate batteries. On this basis, the remaining power of the battery is estimated as accurately as possible, so as to design a reasonable charge and discharge controller for the energy storage device.

[0119] In a possible implementation, the intelligent monitoring system includes:

[0120] A charging control module, installed in the charging device;

[0121] A voltage, current and temperature detection module connected to the lithium iron phosphate battery pack;

[0122] a discharge control module, installed in the discharge device; and

[0123] The main control chip is connected to the charging control module, the voltage, current and temperature detection module and the discharge control module, and is used to upload the working status and detection data of the charging control module, the voltage, current and temperature detection module and the discharge control module to the main control chip for unified management and control by the main control chip.

[0124] In a possible implementation, the remote platform includes a computer, a main control board is installed inside the computer, and the main control board is in communication connection with the communication module and the main control chip in turn, and the computer is used for remote monitoring of voltage data, data transmission and system control functions.

[0125] With the above technical solution, the design of the mobile energy storage device is a systematic project. In terms of the application of basic energy storage functions, it can monitor the status of each component in the energy storage system and the current value of the voltage and parallel network load feeder. If the system detects that there is a power quality problem in the system, the intelligent monitoring system completes the collection of information on the distribution network in remote areas and publishes it to the computer through the main control chip. The computer should change the operating mode according to the instructions and adjust the active and reactive values ​​of each phase output until the load rate of the distribution station area is within a reasonable range and the power quality problem is solved.

[0126] In a possible implementation, the power quality detection module includes a data acquisition unit, a signal processing unit and a classification and identification unit. The data detected by the data acquisition unit includes power quality detection, power flow information detection and equipment operating condition detection. The signal processing unit and the classification and identification unit are used to extract, classify and identify power quality disturbances.

[0127] In a possible implementation, the power quality detection module is respectively connected to each line of the user's power grid, and the power quality detection module is connected to the energy management software, the energy management software is connected to the power conversion module, the power conversion module is connected to the hybrid energy storage unit, and the hybrid energy storage unit is connected to the energy management software.

[0128] In a possible implementation, the power conversion module includes a VSC inverter, one end of which is connected to the user grid line by a filter circuit, the number of the VSC inverters is twice the number of the user grid lines, and the other end of each of the VSC inverters is connected to a common DC bus, the energy-type energy storage system is connected to the common DC bus through the VSC inverter, the power-type energy storage system is also connected to the common DC bus through the VSC inverter, and the energy-type energy storage system, the VSC inverter connected to the energy-type energy storage system, the power-type energy storage system and the VSC inverter connected to the power-type energy storage system together constitute the hybrid energy storage unit.

[0129] Through the above technical solution, before comprehensive power quality management is carried out in remote areas, it is necessary to collect relevant data through the power quality detection module in the early stage, and combine the corresponding basic data to conduct a detailed analysis of the operation status of the distribution network. The data detected by the power quality detection module includes power quality detection, flow information detection, and equipment operation status, so as to obtain the goal of power quality management. During steady-state operation, the energy-type energy storage system performs conventional energy interaction and steady-state power quality regulation through the parallel-side converter. When a dynamic power quality disturbance occurs, the power quality detection module and energy management software will issue a drive instruction to the series / parallel-side converter, and quickly adjust the voltage and current of different phase lines in a targeted manner, and use a frequency division strategy to control the power-type energy storage system / energy-type energy storage system to support the DC bus voltage. At the same time, the constraints of the system's flow, node voltage, branch current, and energy storage core charge state must be met.

[0130] In a possible implementation, the energy storage capacity configuration module uses a multi-objective optimization algorithm to optimize the configuration of the energy storage capacity.

[0131] It should be noted that in order to meet the actual conditions of the distribution network and the basic conditions for safe and stable operation, the optimization model needs to consider the power flow balance of the power grid (including active balance and reactive balance), the upper and lower power limits of the transmission line, the generator and node voltage constraints, the adjustable transformer ratio constraints, the generator output power and climbing rate constraints, and all constraints related to the operation of the mobile energy storage device.

[0132] Equality constraints: The power flow constraints of the system, that is, the active power balance and reactive power balance of the system:

[0133]

[0134]

[0135] Where P Gi , and are the generator active output, RDG active output, and load active demand of node i respectively; Q Gi , are the generator reactive output, RDG reactive output, and load reactive demand of node i respectively; U i is the voltage of node i; G ij and B ij Represent the conductance and susceptance between nodes i and j respectively; θ ij is the phase difference between nodes i and j.

[0136] An inequality constraint consists of the following parts:

[0137] Transmission line power constraints:

[0138] P k ≤P k,max

[0139] Where P k is the active power transmitted by the kth line, P k,max is the upper limit of active power transmitted by the kth line;

[0140] Generator voltage constraints:

[0141] U G,min ≤U G,i ≤U G,max

[0142] Where U G,i is the voltage amplitude of generator i, U G,max and U G,min are the lower and upper limits of the voltage of generator i respectively;

[0143] Node voltage constraints:

[0144] U min ≤U i ≤U max

[0145] Where U i is the voltage amplitude of generator i, U min and U max are the lower and upper limits of the voltage of generator i respectively;

[0146] Adjustable transformer ratio constraints:

[0147] T min ≤T i ≤T max

[0148] Where, T i is the transformation ratio of transformer i, T min and T maxThey are the lower and upper limits of the transformer ratio respectively (Note: When selecting the transformer ratio, select the i closest gear).

[0149] By adopting the above technical scheme, according to the various components existing in the distribution network system, after constructing the corresponding mathematical model, considering that the comprehensive management of power quality has different tendencies in different scenarios, multi-objective optimization is used to characterize the influence of various factors on the capacity configuration of the mobile energy storage device. Then, the multi-objective optimization problem is solved by methods such as vector method or scalar method to obtain the Pareto optimal solution set. On this basis, the entropy weight method or fuzzy comprehensive evaluation method is used to select the compromise optimal solution of the multi-objective optimization problem. In addition, considering the uncertainty of load demand and renewable energy in the context of actual engineering applications, random optimization or robust optimization methods are used to ensure that the optimization results are applicable to a variety of data scenarios. Finally, combined with the constraints of the operating layer in the configuration model, the optimization control strategy of mobile energy storage under the source-grid collaboration idea is formulated for different optimization objectives.

[0150] On the basis of the above technical scheme, the configuration of movable energy storage devices at the terminal substation of the distribution network can effectively improve the power supply quality of the low-voltage substation, optimize the power flow distribution by utilizing the charging and discharging characteristics of energy storage, improve the load rate of heavily overloaded lines, thereby delaying the expansion and transformation of the line, reducing the power supply company's investment in the construction of agricultural low-voltage distribution networks, and realizing the benefits of power asset substitution.

[0151] A method for managing a mobile energy storage and power quality comprehensive management device, comprising the following steps:

[0152] S1. First determine the installation location of the mobile energy storage device and connect it to the user's smart energy meter, collect and monitor the three-phase current value of the installation location of the mobile energy storage device, calculate the average value of the lowest voltage of the low-voltage user, analyze the power quality problem, extract features, and classify the disturbance signal;

[0153] S2. Construct a capacity configuration model of a mobile energy storage device according to various components existing in the distribution network system;

[0154] S3. Based on the source-grid coordination concept and the constraints of the capacity configuration model operation layer, combined with the charging and discharging characteristics and spatiotemporal coupling characteristics of the mobile energy storage device, formulate the control strategy of the mobile energy storage device, determine the installation capacity of the mobile energy storage device and optimize the energy storage time of the comprehensive power quality management device;

[0155] S4. According to the user's minimum voltage value, a target voltage value is set;

[0156] S5. The monitoring and early warning system monitors the power quality and the operating status of the mobile energy storage device in real time, and provides early warning and alarm functions;

[0157] S5. According to the monitoring results and warning information, when all user voltages are qualified, the process ends; when the user voltage is unqualified, return to S4.

[0158] What is described above is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A portable energy storage and power quality comprehensive management device, characterized in that: include: Mobile energy storage devices, including energy storage systems and power storage systems, are used to store and release electrical energy, and the mobile energy storage devices have bidirectional charging and discharging capabilities, and the mobile energy storage devices can be flexibly dispatched according to power quality management requirements; and The comprehensive power quality management device is connected to the user's smart power meter and the movable energy storage device.

2. According to claim 1, a portable energy storage and power quality comprehensive management device is characterized by: The comprehensive power quality control device comprises: Power quality detection module, which is used to collect and analyze power consumption data in remote areas, identify power quality problems, extract features, and classify disturbance signals; An energy storage capacity configuration module, including a capacity configuration model constructed according to components in the power distribution system, for optimizing the configuration of the energy storage capacity of the mobile energy storage device; An optimization control strategy module is used to formulate a control strategy for the mobile energy storage device based on the source-grid coordination concept and the constraints of the capacity configuration model operation layer, and in combination with the charging and discharging characteristics and the spatiotemporal coupling characteristics of the mobile energy storage device, so as to improve the power quality; and The monitoring and early warning system includes an intelligent monitoring system for real-time monitoring of the power quality and the operating status of the movable energy storage device, and providing early warning and alarm functions.

3. According to claim 1, a portable energy storage and power quality comprehensive management device is characterized by: The movable energy storage devices all use lithium iron phosphate battery packs, charging equipment and discharging equipment connected to the lithium iron phosphate battery packs as energy storage battery systems. The energy storage battery systems perform bidirectional energy conversion with the user power grid through energy storage inverters and isolation transformers in turn, and the energy storage inverters are connected to voltage sampling modules and current sampling modules, and the voltage sampling modules and current sampling modules are connected to the upper power grid, and the energy storage inverters and the energy storage battery systems are connected to the intelligent monitoring system, and the intelligent monitoring system is communicatively connected to the remote platform.

4. The portable energy storage and power quality comprehensive management device according to claim 3 is characterized by: The intelligent monitoring system comprises: A charging control module, installed in the charging device; A voltage, current and temperature detection module connected to the lithium iron phosphate battery pack; a discharge control module, installed in the discharge device; and The main control chip is connected to the charging control module, the voltage, current and temperature detection module and the discharge control module, and is used to upload the working status and detection data of the charging control module, the voltage, current and temperature detection module and the discharge control module to the main control chip for unified management and control by the main control chip.

5. The portable energy storage and power quality comprehensive management device according to claim 3 is characterized by: The remote platform includes a computer, a main control board is installed inside the computer, and the main control board is in communication connection with the communication module and the main control chip in sequence. The computer is used for remote monitoring of voltage data, data transmission and system control functions.

6. The portable energy storage and power quality comprehensive management device according to claim 1 is characterized by: The power quality detection module includes a data acquisition unit, a signal processing unit and a classification and identification unit. The data detected by the data acquisition unit includes power quality detection, power flow information detection and equipment operating condition detection. The signal processing unit and the classification and identification unit are used to realize the extraction, classification and identification of power quality disturbances.

7. A portable energy storage and power quality comprehensive management device according to claim 6, characterized in that: The power quality detection module is connected to each line of the user's power grid respectively, and the power quality detection module is connected to the energy management software, the energy management software is connected to the power conversion module, the power conversion module is connected to the hybrid energy storage unit, and the hybrid energy storage unit is connected to the energy management software.

8. The portable energy storage and power quality comprehensive management device according to claim 7 is characterized by: The power conversion module includes a VSC inverter, one end of which is connected to the user power grid line by a filter circuit. The number of the VSC inverters is twice that of the user power grid lines, and the other end of each of the VSC inverters is connected to a common DC bus. The energy-type energy storage system is connected to the common DC bus through the VSC inverter, and the power-type energy storage system is also connected to the common DC bus through the VSC inverter. The energy-type energy storage system, the VSC inverter connected to the energy-type energy storage system, the power-type energy storage system and the VSC inverter connected to the power-type energy storage system together constitute the hybrid energy storage unit.

9. The portable energy storage and power quality comprehensive management device according to claim 1 is characterized by: The energy storage capacity configuration module uses a multi-objective optimization algorithm to optimize the configuration of energy storage capacity.

10. A method for managing a mobile energy storage and power quality comprehensive management device according to any one of claims 1 to 9, characterized in that: The following steps are involved: S1. First determine the installation location of the mobile energy storage device and connect it to the user's smart energy meter, collect and monitor the three-phase current value of the installation location of the mobile energy storage device, calculate the average value of the lowest voltage of the low-voltage user, analyze the power quality problem, extract features, and classify the disturbance signal; S2. Construct a capacity configuration model of a mobile energy storage device according to various components existing in the distribution network system; S3. Based on the source-grid coordination concept and the constraints of the capacity configuration model operation layer, combined with the charging and discharging characteristics and spatiotemporal coupling characteristics of the mobile energy storage device, formulate the control strategy of the mobile energy storage device, determine the installation capacity of the mobile energy storage device and optimize the energy storage time of the comprehensive power quality management device; S4. According to the user's minimum voltage value, a target voltage value is set; S5. The monitoring and early warning system monitors the power quality and the operating status of the mobile energy storage device in real time, and provides early warning and alarm functions; S5. According to the monitoring results and warning information, when all user voltages are qualified, the process ends; when there is an unqualified user voltage, return to S4.

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