CN101630840B - Intelligent control system for microgrid energy - Google Patents

Abstract

The invention relates to a micro power supply and utilization system including multiple distributed power sources. The invention discloses an intelligent energy control system capable of controlling a microgrid by using prediction information. The microgrid energy intelligent control system of the present invention includes a microgrid system and a control system; the microgrid system includes a power supply unit, an energy storage unit and a load unit; the control system includes an information collection system and a central processing unit. The central processing unit includes: load forecasting module; microgrid online state estimation module; intermittent power supply energy forecasting, energy storage unit energy forecasting module; microgrid system analysis module; microgrid multi-objective optimization operation and comprehensive coordination control module. The microgrid energy intelligent control system of the present invention can control the microgrid according to the prediction information, and realize the intelligent operation of the microgrid.

Description

Micro grid energy intelligent control system

technical field

The invention relates to a power system, in particular to a micro power supply and consumption system including multiple distributed power sources.

Background technique

After the North American blackout in August 2003, countries such as Europe and the United States deeply realized the importance of power system reliability. A micro-grid technology that combines generators, loads, energy storage devices, and control devices to form a single controllable unit that simultaneously supplies electricity and heat to users has emerged as the times require. Most of the power sources in the microgrid are micro power sources, that is, small units (generally less than 100kW) with power electronic interfaces, including micro gas turbines, fuel cells, solar power generation devices, wind power generators, biomass power generation devices, supercapacitors, and flywheels. These power generation devices are connected to each other through power electronic devices to complete the functions required by the microgrid system. They are connected to the user side and have the characteristics of low cost, low voltage, and low pollution. The system capacity is 20kW ~ 10MW; the user distribution voltage level in the network is 380V, or including 10.5kV (such as energy exchange with the external grid, the voltage level is determined by the specific application of the microgrid).

In addition to European and American countries, Japan has also attached great importance to the research of micro-grids in recent years. For example, at the 2005 Aichi World Expo, Mitsubishi Corporation demonstrated an energy supply system based on fuel cells, using autonomous load-following control to reduce the impact on the grid. The system uses advanced energy technologies such as fuel cells, solar power, and NaS storage batteries, and uses wood and waste to produce gas fuel for fuel cells. The heat generated by fuel cells is used for air-conditioning systems in buildings. Experiments have proved that this energy The system is a very environmentally friendly power supply and heating system. The ecological energy project in Kyoto, Japan, uses biogas engines, dissolved carbonic acid fuel cells, solar power, wind power, batteries, etc. to form a micro-grid system, which is connected to the public power grid. The impact of grid time on the power system, using biogas-fueled engines and fuel cells to generate electricity to provide electricity to buildings, the total installed capacity of this project reaches 850kW. In July 2006, Shimizu Corporation of Japan built a micro-grid system consisting of gas engines, nickel-metal hydride batteries, and electrical double-layer capacitors. Remote control is used to operate switches such as circuit breakers, and constant power control is performed at grid-connected points. Stabilization control of voltage and frequency is carried out when the system is running independently.

Based on the research results of micro-grids in various countries in the world, micro-grids have the following characteristics:

1) Microgrid usually refers to a distribution network that contains one or more distributed micro power sources near the load center, including but not limited to micro gas turbines, fuel cells, solar power generation devices, wind turbines, biomass power generation devices And supercapacitors, flywheel batteries, storage batteries and other energy storage devices. Microgrids can be connected to large power grids or run independently (such as microgrids built in special geographical environments such as islands and deserts).

2) There are two networks in the microgrid. One consists of busbars, transmission lines, switches, switches, power supplies, loads, heating pipelines, heat sources, etc. It is a network for energy generation, transmission and consumption. The other is between the micro-grid control system and multiple micro-energy sources, loads, switches, lines, pipelines and other controlled objects, relying on protocols such as MODBUS or field bus or Ethernet (but not limited to the above-mentioned protocols, which can be wired It can also be a wireless) information transmission network constructed. The micro-grid control system is the core of the micro-grid. It monitors the status of the micro-grid and automatically realizes the real-time control of the overall operation according to the actual situation according to the pre-established control strategy.

3) The microgrid contains one or more electrical loads. According to the importance of power loads and different requirements for power supply reliability, such loads can be divided into first-class loads, second-class loads and third-class loads, and the importance is in descending order. Microgrids can also include heat loads and heating lines.

4) The microgrid can supply cold, heat and electricity to users, or it can only provide electric energy.

5) The microgrid also includes busbars, switches, knife switches, transmission lines, relay protection devices, energy meters and other devices and units used for electric energy transmission, metering and ensuring the safe operation of the distribution network. Switches, knife switches, relay protection devices, etc. are combined with the control system to become part of the execution unit of the entire microgrid energy intelligent management.

The micro-grid control system is the core of the micro-grid. It monitors the operating status of the entire micro-grid system and manages the operation of the micro-grid according to the pre-established control strategy according to the actual situation. For patents on microgrid control technology, please refer to Chinese patents CN101207284A and CN1964152A.

Both of the above two patents focus on the energy management system of the microgrid. Although some control methods are proposed, they both ignore an important issue - the energy consumption of the load, the energy level and energy storage capacity of the energy storage unit, and the system supply. The prediction of the energy level (all kinds of power generation units) does not take into account the special role of the controllability of the energy storage unit in improving the reliability and power quality of the microgrid. For a complex distributed system like a microgrid, its control is difficult without prediction. At the same time, these two patents do not explicitly mention the automatic early warning and emergency control of dangerous situations.

Contents of the invention

The technical problem to be solved by the present invention is to provide an intelligent energy control system capable of controlling the microgrid by using forecast information.

The present invention solves the technical problem, and adopts the technical solution that the micro-grid energy intelligent control system includes a micro-grid system and a control system; the micro-grid system includes a power supply unit, an energy storage unit and a load unit; the control system includes An information collection unit and a central processing unit; it is characterized in that the central processing unit includes:

Load forecasting module: use the following methods or their combination to predict the ultra-short-term power consumption of large-capacity loads in the microgrid: expert system, fuzzy logic technology, artificial neural network, time series method;

Microgrid online state estimation module: estimate the working state of each unit in the microgrid according to the measured data of the information collection unit;

Intermittent power supply energy prediction, energy storage unit energy prediction module: this part will analyze the energy conversion and storage capacity of the microgrid according to the weather information and the state information of the energy storage unit collected by the information collection unit;

Microgrid system analysis module: on the basis of state estimation, fault analysis, stability analysis, power quality analysis and economic analysis of microgrid are carried out to ensure the safe, stable and economical operation of the whole system;

Micro-grid multi-objective optimal operation and comprehensive coordination control module: According to the different operation modes and control requirements of the micro-grid, on the basis of micro-grid state estimation and system analysis, analyze the intermittent power supply and energy storage unit control under different operating modes of the micro-grid system According to the relationship between strategies and system performance indicators, specific quantitative instructions are given to each unit according to the pre-established control objectives; joint optimal control is performed on each unit within the entire microgrid to realize the closed-loop operation of the microgrid;

The information collection unit includes:

Power supply unit information acquisition module: used to detect the working status of various power supplies and transmit information to the central processing unit;

Energy storage unit information acquisition module: used to detect the parameters and working status of the storage battery, super capacitor and flywheel battery in the energy storage unit, and transmit information to the central processing unit;

Load unit information collection module: used to detect the output power and power consumption parameters of various loads in the load unit, and transmit information to the central processing unit;

Further, the central processing unit also includes a distributed flexible energy storage control module, which is used to analyze the difference in operating characteristics of the system energy storage units, the current state and its impact on the system, and the future period of time based on the system analysis. According to the data of load forecasting and intermittent power output power forecasting, according to the principle of coordinated operation, determine which energy storage unit is used to dynamically store and release energy, so as to achieve the optimal energy matching of the system;

Specifically, the large-capacity load refers to a load that consumes power ≥ 5% of the capacity of the microgrid;

Specifically, the ultra-short-term power consumption prediction refers to the power consumption prediction within 5 minutes to 1 hour;

Specifically, the intermittent power supply includes, but is not limited to, wind power generation devices, solar power generation devices, and small hydroelectric power generation devices;

Further, the central processing unit also includes: an emergency control unit, configured to handle emergency failures of the entire microgrid;

Further, the microgrid system and the control system constitute an autonomous system, which can operate independently, or operate under human intervention through human-computer interaction through the computer of the control system.

The beneficial effects of the present invention are that a method for predictive control of the micro-grid is proposed, the control function of the micro-grid is further improved, the distributed control of a system with a complex structure is more easily realized, and the control accuracy and effectiveness of the micro-grid are improved.

Description of drawings

Figure 1 is a schematic diagram of the microgrid structure;

Figure 2 is a schematic diagram of the working principle of the control system;

Figure 3 is a schematic diagram of the multi-objective optimal operation and comprehensive coordination control process of the microgrid.

Detailed ways

The technical solution of the present invention will be described in detail below in conjunction with the accompanying drawings and embodiments.

The microgrid energy intelligent control system of the present invention is the control center for the normal operation of the microgrid. It uses MODBUS or other communication protocols to connect the monitoring parts of power generation, energy storage, heating, load, transmission lines, relay protection devices, switch switches and other units in the microgrid, and can be connected with the energy management system of the large grid ( EMS) exchange information to realize the status monitoring of microgrid operation and automatic multi-objective comprehensive optimal operation. The refresh time of the control system is about seconds.

Example

The structure of the entire microgrid system is shown in Figure 1, and only the parts related to electric energy are drawn in the figure. The working principle of the control system in this example is shown in Figure 2.

To effectively control the complex system shown in Figure 1, the control system of the present invention adds functions such as predictive control of each unit in addition to some control functions of the conventional system. The control system of this example can be divided into information collection units, Communication network and central processing unit and other parts, the corresponding functional modules and working principles of each part are as follows:

Information collection unit:

In general, the collected information includes status detection information of each unit in the microgrid, data from the energy management system of the large power grid, and weather information. The latter two sources of information are mainly used for load forecasting of microgrids and forecasting of power generation devices that are greatly affected by meteorological factors. If the monitoring device in the microgrid system can detect the electrical parameter information of the nodes connected to the microgrid and the large grid in real time, and the energy exchange between the microgrid and the large grid is not large (has no major impact on the operation of the microgrid) In this case, the data from the EMS of the large power grid may not be required. In addition, if the load in the microgrid is not sensitive to weather and does not include solar energy and other power sources that are greatly affected by weather factors, there is no need to input weather information. Therefore, the information collection unit may only contain the state detection information of each unit in the microgrid.

The units of the microgrid include power supply units, energy storage units, switch switches, relay protection devices, load units, AC/DC rectifiers or inverters, transmission lines, and other monitoring devices in the microgrid. For these units and devices, information such as voltage, current, active power, reactive power, system frequency and other information detected by the sensors in the information collection unit, as well as the status of each unit (such as the switch is closed or disconnected, the active power output by the power supply unit, and the external Exchanged reactive power, load power factor, etc.) information, and then transmit these data to the control system through the communication network, see Figure 1.

The communication network is mainly responsible for transmitting the information from the information acquisition unit to the control system, and at the same time sending the control commands of the control system to each controlled unit, and the relevant information is displayed on the human-computer interaction interface, and it can also support remote Web browsing.

Communication protocols for information transmission include but are not limited to protocols such as MODBUS, Fieldbus, and Ethernet. In terms of implementation, it can be wired or wireless, and it can use optical fiber communication or other communication methods such as microwave communication or power line carrier.

central processing unit

The central processing unit of the microgrid control system receives the detection information from each unit through the information transmission unit, and then the computer control software in it will analyze and control according to these information. The specific functional modules of the central processing unit include:

(1) Load forecasting module: provide 5-minute to 1-hour load forecasting data to the central processing unit. The characteristic of microgrid is to use renewable energy and provide targeted energy services for various loads. Since the output power of renewable energy such as wind energy and solar energy is greatly affected by meteorological conditions, during the operation of the microgrid, special attention must be paid to the ultra-short-term forecasting of loads, so that control measures can be taken early to ensure the reliability of power supply.

For a microgrid, usually, the number of loads and power consumption characteristics are often predictable. For example, the loads in a microgrid can be divided into urban residential loads, commercial loads, rural loads, industrial loads and other loads ( Other loads include municipal electricity, public utilities, government offices, railways and trams, military, etc.). These different types of loads are connected to different buses in the microgrid, and each has different power consumption characteristics. In load forecasting, according to the characteristics of these loads (such as sensitivity to weather temperature and time, etc.), appropriate load forecasting methods or combinations of different methods (such as artificial neural networks, time series, fuzzy logic and expert system, wavelet analysis, etc.), predict the load on each microgrid bus, and compare and analyze the predicted results and the load on the actual bus, and adjust some coefficients of the load forecasting tool online, so as to obtain a suitable Load forecasting tool on load characteristics. At the same time, the actual bus load results should also be classified and stored in the database in combination with the weather conditions, holiday factors, and load industry characteristics at that time. In this way, in future load forecasting, when encountering similar weather and holidays, these measured data can be used as historical data to participate in forecasting.

For a general microgrid, the number of microgrid loads controlled by its control system is usually less than a few hundred (usually dozens of loads), which makes a certain large and medium-capacity load (such as power consumption ≥ 5% of the microgrid capacity) load), the change of its power consumption often has a significant impact on the entire microgrid (especially when the microgrid operates independently). At the same time, the characteristics of these loads (such as which industry they belong to, power consumption characteristics, etc.) can often be known in advance. Therefore, compared with the large power grid, the microgrid control center can adjust the load forecasting tool and its parameters online according to the characteristics of the load when modeling the load.

(2) Microgrid online state estimation module: the system state is the basis of microgrid management and operation control, and system analysis is the premise of microgrid operation control. Due to the working characteristics of the intermittent power supply and energy storage unit in the microgrid system, as well as the complexity of the operation mode of the entire system, the existing power system analysis theories and methods cannot be directly applied to the state estimation and system analysis of the microgrid. Considering the random fluctuation of intermittent power output power and the impact of distributed energy storage units, it is necessary to use state estimation technology based on random power flow. Different from the EMS of the large power grid, the EMS of the micro grid needs to be refreshed in a few seconds. Therefore, this also puts forward higher requirements for the communication network and calculation of the system.

Intermittent power supply energy prediction, energy storage unit energy prediction module: this part will analyze the energy conversion and storage capacity of the microgrid according to the weather information and the state information of the energy storage unit transmitted back from the information collection unit, so as to facilitate the power supply Reliability analysis and realization of distributed flexible energy storage technology. The intermittent power supply in the microgrid generally includes wind power generation devices, solar power generation devices, small hydropower generation devices, tidal power generation devices, etc.

Considering that the capacity of the power supply in the microgrid is usually relatively small and comes from different manufacturers, and the application environment of the microgrid is changeable (such as islands, deserts, residential communities, etc., the application objects of the microgrid control system are also Therefore, in terms of energy prediction of microgrids, it is usually not to establish an accurate mathematical model, but to consider the use of measured historical data, combined with the relationship between weather forecast data and power output power, and apply statistical methods to predict. Commonly used prediction methods include artificial neural networks (ANN), expert systems (ES), and support vector machines (SVM).

For energy storage units such as batteries, flywheel batteries, and supercapacitors, the stored energy and the energy that can be released (including stored) mainly rely on the equipment characteristic curve provided by the manufacturer or the equipment characteristic curve determined in advance by the microgrid control center. Prediction of energy storage status and prediction of releasable (including stored) energy. Typically, these characteristic curves take into account the effects of changes in weather information, total operating time of the equipment, rate of change in energy output, equipment efficiency, etc.

(3) Microgrid system analysis module: Similar to the large power grid, the microgrid can perform fault analysis, stability analysis, power quality analysis and economic analysis of the microgrid on the basis of state estimation.

Fault analysis is to analyze the system overvoltage, overcurrent and other states in the steady state after losing (or putting in) any intermittent power supply or energy storage device or load under the current operating state of the microgrid to ensure the safety and security of the system operation. Power supply is reliable. If the above situation occurs, the system will have safety problems, you can take measures such as adjusting the operation mode of the system, releasing/increasing the energy in the energy storage unit, cutting off the energy of some unimportant loads, etc. to change the operation mode of the system, Ensure the safe operation of the system. The loads in the microgrid are mostly small and medium loads, and their switching and switching may not be issued by the control center. Therefore, similar to the large power grid, the microgrid needs to meet the N-1 principle in the scheduling process, that is, the power system N-1 analyze. That is, any device (such as lines, generators, transformers, loads, etc.) in the power system under normal operation mode is not faulty or disconnected due to faults (these disconnected lines, transformers, generators, loads, etc. are the expected fault set ), the power system should be able to maintain stable operation and normal power supply, other devices should not be overloaded, and the voltage and frequency should be within the allowable range. However, considering that the switching and switching of loads in the microgrid may not be controlled by the control center, and compared with the capacity of the microgrid, the switching of these loads has a relatively large impact on the operation of the microgrid. During fault analysis, it is also necessary to consider the situation of a certain load input, that is, the situation of N+1.

Stability analysis is the ability of the system to recover to the original operating state or transition to a new stable state after the microgrid is subjected to slight or large disturbances in the current operating state. The small disturbance here includes the output power of an intermittent power supply or energy storage device, the small changes in the impedance of the transmission line, the power consumption of the load, and so on. Large disturbances refer to transmission line outage, three-phase short circuit, one-phase grounding, loss of a certain power source or energy storage device in the system, loss of a certain load in the system, etc. If the result of the stability analysis is unstable, the control center should formulate corresponding emergency control measures according to the operating state of the system, and ensure the system’s stability by means of load shedding, energy storage unit release or increase energy storage, and adjustment of system operation mode. Stablize.

The power quality analysis is based on the current power quality monitoring data to analyze the current situation of the power quality of the microgrid, and to formulate a strategy for the online compensation and control of the power quality.

Economic analysis is a method to study the lowest operating cost and the highest benefit of the system under a certain operating state. Due to the different generation costs of different intermittent power sources, the differences in energy storage costs of different types of energy storage devices, and the different economic and social benefits generated by different load operations, for microgrids, through economic analysis, we can Realize the operation mode with the lowest operating cost and the highest benefit for the entire system.

(4) Micro-grid multi-objective optimal operation and comprehensive coordination control module: According to the different operation modes and control requirements of micro-grid, on the basis of micro-grid state estimation and system analysis theory, analyze the micro-grid under grid-connected/stand-alone operation mode The relationship between the system state, intermittent power supply and energy storage unit control strategy, and system performance indicators, the joint optimal control of each unit in the entire micro-grid system, and specific quantitative instructions for each unit, to achieve micro-grid Closed-loop operation of the grid. At the same time, according to the real-time status and forecast information of the system, the control strategy is adjusted online according to the pre-established control objectives. Common control objectives include: optimal system economy, reliability of power supply, optimal distribution of energy storage, etc. Under normal circumstances, the priority is to consider the optimal system economy. But for some important loads, if there are special requirements for power supply reliability and power quality, these specific requirements can be listed as priority control targets and set on the human-computer interface. The flowchart of multi-objective optimal operation and comprehensive coordination control of microgrid is shown in Fig. 3.

The central processing unit in this example also includes a distributed flexible energy storage control module and a power quality joint compensation control module. Distributed flexible energy storage is proposed based on the controllability of energy conversion of energy storage units and considering the differences in dynamic characteristics of different energy storage devices in different spaces of the microgrid. The basic principle is based on system analysis, according to the differences in the operating characteristics of each energy storage device and the current state (such as the current energy storage efficiency of each energy storage device, charging and discharging characteristics, predicted current remaining electric energy, etc.) The impact of the system, as well as the data of load forecasting and intermittent power output forecasting for a period of time in the future, according to the principle of coordinated operation, determine which energy storage unit is used to dynamically store and release energy, so as to achieve the optimal energy of the system Matching, so as to ensure that the system can run in an optimized state at present or in the future.

Power quality is the focus of some important power users, and it is also the characteristic and advantage of microgrid. The real-time detection and joint compensation technology of power quality aims at the typical power quality problems of microgrid (frequency deviation, voltage amplitude deviation and waveform quality), according to the dynamic characteristics and spatial relationship of different compensation units (power supply, energy storage unit and compensation equipment), Determine the optimal power quality compensation strategy.

The energy storage unit in the microgrid can be divided into two types. One is the energy storage unit that is not controlled by the control system. The control strategy of this type of energy storage unit is generally the local control strategy of the device itself. The other is the energy storage unit controlled by the control system, whose energy flow direction and size are controlled by the control system. In order to make full use of the controllability of energy output/input of energy storage devices located in different spatial positions and different dynamic response characteristics of the microgrid, and to give full play to the advantages of energy storage devices in providing support for the reliability and power quality of nearby loads, the storage In the energy status assessment link, relying on the rules formulated by the small expert system to implement the strategy of distributed flexible energy storage, to ensure the optimal coordination of the load unit, energy storage unit and power unit of the system.

The first factor that needs to be considered by the distributed flexible energy storage control module is to ensure that the energy stored in the energy storage unit can match the load and power generation forecast of the system; the second factor is to consider the impact of load characteristics on the control of the energy storage unit; The third factor is to consider that the different dynamic characteristics of the energy storage unit may have an impact on the load power supply; the fourth factor is to consider the economic factors of energy storage; the fifth factor is the limit of the charge and discharge times of the energy storage unit, Discharging time limit, etc. (for example, the battery energy storage unit cannot perform frequent charging and discharging operations, otherwise it will affect the life of the battery). All these need to be considered in the distributed flexible energy storage control module.

After the power quality assessment and energy storage state assessment, if adjustment measures need to be taken, such adjustment measures generally issue instructions to adjust energy storage for certain controlled energy In general, the delayed execution of such instructions will not seriously affect the stability and security of the system, so fault checking and stability analysis are not directly performed in the current control cycle. Since the energy management system implements automatic closed-loop control, and the refresh time is about seconds, such control instructions can be included in the system state changes in the next cycle evaluation, and then the fault check and stability analysis can be performed.

Another additional control module of the central processing unit in this example is an emergency control unit, which is used to handle emergency failures of the entire microgrid. It has the functions of automatic warning of dangerous situations, auxiliary decision-making and emergency control. It can automatically evaluate the security status of the system according to the current operating status and control strategy of the system. If a dangerous situation occurs in the system due to some reasons (such as the system hazard caused by sudden lightning), or it is predicted that a dangerous situation may occur, the computer-aided decision-making will be automatically carried out, and the relevant staff will be prompted by means of sound and light alarms, and then Information such as hazard sources and solution suggestions are displayed on the man-machine interface, and emergency control of the system can be implemented automatically or with manual intervention.

Compared with the above multi-objective optimal operation and comprehensive coordination control, emergency control has the highest priority.

Usually, the protection switch device can judge the opening and closing by itself in the event of an accident, and then communicate its own state with the central processing unit, and accept and execute control instructions.

The human-computer interaction interface module of this example:

During the operation of the microgrid, there will be some technical information, such as the system status, the working status of the renewable power generation device, the relevant conclusions of the microgrid system analysis, the early warning analysis conclusions of the microgrid and the auxiliary decision-making strategies, etc. These information will be displayed on the control panel. on the computer screen in the center. At the same time, remote monitoring of microgrid operation can also be realized by means of Web browsing with the help of existing programming languages and networks.

Control System Workflow

The control system realizes online closed-loop control according to the process of information collection, analysis and decision-making, execution unit action, and information display on the man-machine interface.

First of all, the information collection unit is responsible for collecting data from various units of the microgrid, EMS of the large power grid, weather forecast information, etc., and then input these information into the control system through the field bus or other communication methods.

According to the input information, the control system automatically implements load forecasting, energy storage situation analysis, and state estimation, and then performs fault analysis, reliability analysis, economic analysis, stability analysis, and automatic early warning analysis of the microgrid. out microgrid control strategy.

Information such as the status, control strategy, and emergency control measures of the microgrid will be displayed on the man-machine interface for reference by operation monitoring personnel.

Compared with the control system of the microgrid in the prior art, the present invention has several characteristics:

1. Intelligence. Modules and algorithms such as load forecasting, power generation forecasting, online learning and dynamic adjustment of optimization parameters, expert system, multi-objective optimization, fault analysis and emergency control have been added to ensure that the system can operate autonomously without human intervention.

2. Distributed coordinated closed-loop control. The comprehensive and coordinated control information is transmitted to each control unit after the microgrid system level control and each subunit control module, and then the system state of the microgrid is reacquired through system state estimation, and used to formulate a new control strategy. In this way, a distributed coordinated closed-loop control system is formed, which helps to overcome the influence of the dynamic characteristics of each unit in the microgrid system on the system, and ensures the real-time optimal operation of the system. Considering that there are fast-response units in the microgrid and the operation mode of the microgrid is changeable, the refresh time of the control system is at the second level.

3. It is clearly stated that the load forecasting in the microgrid is ultra-short-term/real-time load forecasting. The way of load forecasting can be based on the characteristics of each load, choose the appropriate load forecasting method, and adjust some parameters in the forecasting method or forecasting tool online according to the forecast error.

4. Clearly put forward the power generation prediction method and the energy storage analysis method of the energy storage unit in the microgrid.

5. It is clearly stated that the input of large and medium capacity loads should be considered in the fault analysis of the microgrid. And it is pointed out that the mathematical models and analysis tools used in failure analysis and stability analysis are different.

6. Clearly put forward online analysis and joint compensation of power quality: due to the changeable operation mode of the microgrid, the energy management system realizes online analysis and joint compensation of power quality by coordinating and controlling energy storage units and other power quality supplementary units.

7. Clearly put forward the distributed and flexible energy storage control: the energy storage unit is the controllable energy output unit in the microgrid, which plays an important role in the safe operation of the microgrid. The energy management system will realize the optimal storage of energy according to the real-time status of the system and the control objectives.

8. Added automatic early warning and auxiliary decision-making functions for dangerous situations in the system, and displayed relevant information on the man-machine interface.

Claims (6)

1. The microgrid energy intelligent control system includes a microgrid system and a control system; the microgrid system includes a power supply unit, an energy storage unit and a load unit; the control system includes an information collection unit and a central processing unit; it is characterized in that, The central processing unit includes: Load forecasting module: use the following methods or their combination to predict the ultra-short-term power consumption of large-capacity loads in the microgrid: expert system, fuzzy logic technology, artificial neural network, time series method; Microgrid online state estimation module: estimate the working state of each unit in the microgrid according to the measured data of the information collection unit; Intermittent power supply energy prediction, energy storage unit energy prediction module: this part will analyze the energy conversion and storage capacity of the microgrid according to the weather information and the state information of the energy storage unit collected by the information collection unit; Microgrid system analysis module: on the basis of state estimation, fault analysis, stability analysis, power quality analysis and economic analysis of microgrid are carried out to ensure the safe, stable and economical operation of the entire system; Micro-grid multi-objective optimal operation and comprehensive coordination control module: According to the different operation modes and control requirements of the micro-grid, on the basis of micro-grid state estimation and system analysis, analyze the intermittent power supply and energy storage unit control under different operating modes of the micro-grid system According to the relationship between strategies and system performance indicators, specific quantitative instructions are given to each unit according to the pre-established control objectives; joint optimal control is performed on each unit within the entire microgrid to realize the closed-loop operation of the microgrid; The information collection unit includes: Power supply unit information acquisition module: used to detect the working status of various power supplies and transmit information to the central processing unit; Energy storage unit information acquisition module: used to detect the parameters and working status of the storage battery, super capacitor and flywheel battery in the energy storage unit, and transmit information to the central processing unit; Load unit information collection module: used to detect the output power and electric energy consumption parameters of various loads in the load unit, and transmit information to the central processing unit. 2. The microgrid energy intelligent control system according to claim 1, wherein the central processing unit also includes a distributed flexible energy storage control module, which is used to operate according to the system energy storage unit on the basis of system analysis The difference in characteristics and the current state and its impact on the system, as well as the data of load forecasting and intermittent power output forecasting for a period of time in the future, according to the principle of coordinated operation, determine which energy storage unit will dynamically store and release energy. The technology realizes the optimal energy matching of the system. 3. The micro-grid energy intelligent control system according to claim 1, wherein the large-capacity load refers to a load whose power consumption is greater than or equal to 5% of the capacity of the micro-grid. 4 . The microgrid energy intelligent control system according to claim 1 , wherein the ultra-short-term power consumption prediction refers to the power consumption prediction within 5 minutes to 1 hour. 5 . The microgrid energy intelligent control system according to claim 1 , wherein the central processing unit further comprises: an emergency control unit, configured to handle emergency failures of the entire microgrid. 6. The micro-grid energy intelligent control system according to claim 1, wherein the micro-grid system and the control system constitute an autonomous system, which can operate independently, or perform human-computer interaction through the computer of the control system, run with human intervention.

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