In the wind solar complementary LED street lamp, the controller mainly includes three parts: wind power control unit, photoelectric control unit and battery charge and discharge control unit. The control part controls the operation mode and disconnection of the wind turbine and solar cell array according to the sunshine intensity, wind power and load changes, and the charging condition of the battery, and constantly switches and adjusts the working state of the battery. On the one hand, the adjusted electric energy is directly sent to the DC load, on the other hand, the excess electric energy is sent to the battery pack for storage. When the power generation cannot meet the needs of the load, the controller sends the electric energy of the battery to the load, so as to ensure the normal power supply of the load, the safe operation of all parts of the system and the continuity and stability of the whole system.
The wind solar complementary LED street lamp controller is composed of some electronic components, such as resistors, capacitors, semiconductor devices, relays, etc. Simply put, the controller is a “switch”. For the wind power generation part, when the AC generated by the wind turbine generator is rectified, when the battery voltage is lower than the set voltage of the system, the controller turns on the charging circuit to charge the battery. When the battery voltage rises to the protection voltage, the charging control switch circuit stops charging the battery to avoid overcharging the battery. However, according to the charging characteristics of the battery, at this time, the battery voltage will slowly drop. In order to prevent insufficient charging of the battery, when the voltage drops to a certain value, the charging control switch will be turned on, and the battery will be automatically recharged. This state will remain until the next charging protection.
The controller is the key component of the management and control of the wind solar complementary LED street lamp. Its biggest function is to comprehensively manage the battery. The high-performance controller should set various key parameter points according to the characteristics of the battery, such as the overcharge point, discharge point, recovery connection point, etc. When selecting the controller, special attention should be paid to the parameters of the controller’s recovery connection point. Due to the voltage self recovery characteristics of the battery, when the battery is in the over discharge state, the controller cuts off the load, and then the battery voltage recovers. If the parameter points of the controller are not set properly, the service life of the battery and the electrical load may be shortened.
The controller in the wind solar complementary LED street lamp must have the protection functions of battery overcharge protection, over discharge protection, anti reverse connection and so on. In places with large temperature difference, the controller should also have the function of temperature compensation, light control and time control, and should have the function of automatic load switching at night, so as to extend the working time of the street lamp in rainy days. For the design of wind solar complementary LED street lamp, the success or failure often depends on the type selection and design of the controller. Without a controller with good performance, it is impossible to have a wind solar complementary LED street lamp with good performance.
The realization method of the anti reverse charging function of the controller is to connect a diode in series in the charging circuit to prevent reverse charging. This diode should be Schottky diode, and the voltage drop of Schottky diode is lower than that of ordinary diode. In addition, field effect transistor can also be used to prevent reverse charging, and its tube voltage drop is lower than that of Schottky diode. The realization method of the anti overcharge control function of the controller is to connect a discharge transistor in series or in parallel in the input circuit, and the voltage identification circuit controls the switch of the transistor to discharge the excess electric energy generated by the wind solar complementary power generation part through the transistor, so as to ensure that there is no excessive voltage to charge the battery.
The realization method of the anti over discharge function of the controller is to set the discharge cut-off voltage. Because the load power of the wind solar complementary LED street lamp is discharged at a small rate relative to the battery, the discharge cut-off voltage should not be too low. As the battery voltage control point changes with the ambient temperature, the controller of wind solar complementary LED street lamp should have a reference voltage controlled by temperature. For a single lead-acid battery, it is -3~-7mv/ ℃, which is usually -4mv/ ℃.
The MOSFET charging module driven by the controller can select MOSFETs with different voltage levels according to different systems to realize the charge and discharge management of the battery by the system. The control module is designed according to different MOSFET gate voltages, and the output state of the MOSFET module is controlled by the intelligent controller. The controller is composed of LCD liquid crystal display module, keyboard and MCU. It is the core of wind solar complementary LED street lamp control and management. It drives the MOSFET charging module to realize the double standard and three-stage charging of the battery, as well as real-time protection and data reproduction and transmission. At the same time, it provides the magnetoelectric speed limit protection of the wind turbine generator. When the wind turbine generator is over powered, it gives the wind turbine generator the reverse reluctance torque and reduces the speed of the wind turbine generator.
The wind solar complementary LED street lamp controller should be able to use solar energy and wind energy at the same time, so as to improve the comprehensive utilization efficiency of wind energy and solar energy. The controller must have wind power charging circuit and photovoltaic charging circuit, and the two charging channels should be independent and effectively isolated. The maximum power of the wind power charging circuit of the controller shall be greater than or equal to 2 times the rated output power of the wind turbine. The maximum power of the photovoltaic charging circuit of the controller shall be greater than 1.5 times the power of the photovoltaic system. The controller shall have communication interface and reserve DC charging interface. The electromagnetic compatibility of the controller shall meet the requirements of relevant specifications.
The wind solar complementary LED street lamp controller is an intelligent controller integrating wind and solar power generation control. The controller can not only efficiently convert the electric energy generated by wind turbines and solar cells to charge the battery, but also provide various control and protection functions required by the system.
The controller adopts PWM stepless unloading method to control the wind turbine and solar cell to intelligently charge the battery. When the electric energy generated by the solar cell and wind turbine exceeds the storage capacity of the battery, the control system must consume the excess energy. The common control method is to connect the whole unloaded load. At this time, the battery is generally not full, but all the energy is consumed on the unloaded load, resulting in a waste of energy. Some of them connect the unloading load in stages. The more stages, the better the control effect. But generally, it can only achieve about five or six levels, so the effect is still not ideal. The best control method is to use PWM (pulse width modulation) for stepless unloading. Under normal unloading conditions, it can ensure that the battery voltage is always stable at the floating charge voltage point, and only release the excess electric energy to the unloaded load. Thus, the best charging characteristics of the battery are guaranteed, and the electric energy is fully utilized.
Because the battery can only withstand a certain charging current and floating voltage, over-current and over-voltage charging will cause serious damage to the battery. The wind solar complementary controller detects the charging voltage and current of the battery in real time through the microprocessor, and limits the charging voltage and current of the battery by controlling the output current of the wind turbine generator and the output current of the photovoltaic power generation unit, so as to ensure that the battery can be fully charged without damage, thus ensuring the service life of the battery.
The wind solar complementary controller takes microprocessor as the core and adopts modern power electronic modular technology to make the peripheral circuit structure simple, and the control mode and control strategy flexible and powerful, so as to achieve excellent performance such as high charging efficiency and low no-load loss. The main functions of the wind solar complementary controller are:
(1) Start the wind turbine automatically according to the preset wind speed (generally 3~4m/s), and realize automatic shutdown when the wind speed is greater than the maximum operating speed (generally set as 25m/s).
(2) The control of photovoltaic power generation adopts microprocessor as the main controller to realize various control and protection functions through the detection and determination of battery voltage, ambient temperature, solar cell voltage and other parameters. Based on the intelligent maximum power tracking mode, ensure the highest utilization of electric energy. By controlling the output voltage of the step-up / step-down dcidc converter, the output current of the wind turbine generator and solar cell array is controlled. By adjusting the output current of the dc/dc converter, the wind turbine generator unit always works at the maximum power point, which is the so-called maximum power point tracking (MPPT) control.
(3) The control of wind power generation adopts microprocessor and PWM charging mode, which can efficiently charge the battery. At the same time, it has perfect functions such as battery voltage monitoring, controller temperature monitoring, manual fan shutdown and charging indication.
(4) The wind solar complementary power generation adopts interleaved parallel control, and the two converters are controlled by DSP respectively. The PWM pulse phase difference of their output voltage is 180 “. Compared with the traditional control mode, its current fluctuation amplitude and electromagnetic interference can be reduced.
(5) DC bus voltage control. The stability control of DC bus voltage is completed by the battery, which is connected to the DC bus through a dcidc converter with bidirectional energy flow.
(6) Intelligently control the discharge current to ensure the maximum output current.
(7) It has a DSP data acquisition and storage system, which can collect and process the power generation data and power consumption data of solar cell array and wind turbine, and has the yaw / braking control function, data remote transmission function and remote control function in case of strong wind.
(8) Data monitoring. The data monitoring of the wind solar complementary LED street lamp can obtain the operation data of the wind solar complementary power generation part in real time through the monitoring system and monitor various alarms, so as to provide basic operation data for equipment maintenance and management.
The controller of wind solar complementary power generation takes microprocessor as the control core, which can operate independently, and communicates with the upper computer through RS-485 to form a monitoring system. In the system, the upper computer is mainly used to complete the control of keyboard, LCD and indicator light, as well as the functions of data exchange and communication. The block diagram of wind solar complementary power generation control system is shown in Figure 1-1.
According to the changes of wind and solar radiation, the wind solar complementary power generation part can realize three operation modes: wind turbine generator unit supplying power to the load alone, photovoltaic power generation unit supplying power to the load alone, and wind turbine generator unit and photovoltaic power generation unit supplying power to the load jointly. The wind solar complementary power generation part is divided into charging state, load state (discharge state) and protection state according to the operation state. The system simultaneously monitors the status of photovoltaic power generation units, wind power generation units, loads and battery packs, and enters the corresponding state under corresponding conditions. In each state, not only the work of its own stage is completed, but also the corresponding system parameter display, communication between multiple systems and communication between the system and the upper computer can be given as needed. The system state flow chart is shown in Figure 1-2.
During initialization, the system completes the setting of parameters, such as voltage, current, load, overvoltage and overcurrent parameters of photovoltaic power generation unit; Magnetoelectric protection parameters of wind turbine; Charging coefficient of double standard three-stage charging of lead-acid battery. At the same time, it also completes the initialization of human-machine communication (keyboard, LCD module, led, etc.) and the setting of universal serial communication module of the system.
The system judges the state of the system through real-time sampling module, upper computer trigger signal and user control signal. First, the real-time voltage and current of the system are collected by the real-time sampling module to judge the status of photovoltaic power generation unit, wind power generation unit, lead-acid battery and load, so as to determine the state of the system. Secondly, the upper computer trigger signal and user control signal also jointly control the system state, which can forcibly control the system from one state to another.
In the charging state, the system charges the lead-acid battery with the double standard three-stage charging method, collects the status of the photovoltaic power generation unit, wind power generation unit, battery and load in the system online, reasonably completes the charging and overvoltage constant charging, and maintains the voltage and capacity of the battery in the floating state. In the load state (discharge state), DC power is provided to the load as required by the load.
At the same time, monitor the state of the battery pack to avoid damage to the lead-acid battery caused by excessive discharge.
When the photovoltaic power generation unit, wind power generation unit, battery, load and the internal state parameters of the system in the wind solar complementary LED street lamp controller reach the set protection value, the system enters the protection state, avoiding the harm to the system caused by short circuit, overvoltage, overcurrent and so on, and ensuring the normal operation of the system, such as the magnetoelectric speed limit protection of the wind turbine, the over discharge protection of the battery, and the overvoltage protection of the load.
At the same time, the system provides a convenient man-machine interface, which can obtain the charging / discharging current, voltage parameters and system state parameters online. The universal serial communication module provides communication between systems and between the system and the upper computer. Convenient input control, multiple display outputs and flexible communication not only ensure the safe operation of the system, but also facilitate the maintenance, overhaul and management of the system.
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