Introduction: Photo-voltaic power generation is using solar cells to convert sunlight directly into electricity according to the principle of photo-voltaic effect. It is widely used in the field of transportation , Communication, Oil, Ocean , meteorology and residential life, not only because of its safety and reliability but also Eco-friendly. The example what we are going to introduce below : How does Haiwell PLC work in the field of photo-voltaic power generation. system etc. Photo-voltaic power generation system consists of solar cell phalanx, galvanic battery charge and discharge controller, inverter, ac power distribution cabinet, solar tracking control system and other equipment.
Solar-tracker system Principle
The sun trajectory tracking system. The sun moves all the time, so the direction of the sunlight changes all the time , if the solar panel can face the sun all the time, then the generating efficiency will be the biggest. For the time being , the common sun tracking control system need to work out the exact local direction of the sunlight at any time of any day in a year and save the data of position of the sun in the PLC. The tracking is based on the calculation data of the local sunlight direction.
The sensor tracking . The sensor tracking is to sense the sunlight direction , if the sunlight is deviating from the vertical plane of the solar panel,then the sensor would give out a signal, this signal will be amplified and converted to standard signal,which is going to be sent to PLC via Analog input channel. And the PLC will process the signal and give out the digital signal output to control the system , so that the tracking system could face the sunlight again. .
Introduction of square solar cells network
1. The frame of the Solar cells
The frame of the networking of thousands of Solar-trackers. There are thousands of Solar-tracker in one solar power station, Haiwell PLC and Haiwell H04TCP-4 protocol gateway are very powerful in networking, many squares of solar cells are connected to Ethernet-fiber optic switch, and in the central control room, thousands of haiwel plc can be monitored by the Ethernet transmission.
2. Mainly systematic hardware equipments
2.1 Haiwell PLC
Haiwell PLC,using AI input (ranging 0~10V) with 12-bit AD conversion (Common 0~20mA ). Haiwell plc can connect to Light sensor directly. And Haiwell plc CPU has built-in 2 communication ports and can be extended to maximum 5communication ports, each communication port can be used for programming and can work as slave or host station. The networking mode of haiwell plc can be like 1:N, N:1, N:N, it supports HMI and could be connected to any third-party communication equipment . (like transducer, instrument Bar-code scanner etc.)
2.2 H01TCP-4 protocol gateway modulo.
a. Support transforming different protocols into standard Modbus TCP protocol or Modbus RTU protocol simultaneously
b. Support multiple upper PC clients access the gateway to monitor the equipment simultaneously
c. Using Use address mapping mode in order to realize the rapid response to the TCP client request
d. Built-in WEB server, the user can use the browser to view real-time state of communication and the change of the data, convenient for debugging on site
e. Support analog linear transformation, fetch bit, high and low byte exchange, etc
f. Two Ethernet ports, 4 isolated RS485 communication port
2.3 Fiber optics-Ethernet switch, Central Control Room SCADA System
3. Data acquisition and control principle
Every Sloar-tracker contains one haiwell PLC, Haiwell plc is receiving the signal of sunlight position from sensor via the analog input channel. After processing by the user program , the plc will give out signal to control the rotation of the sunlight receiver to face the velocity direction of the sunlight to work more efficently .
H01TCP has four RS485 communication ports,each port connect with 15 sets of plc. The ports of the H01TCP collects the data from PLC and save it to the internal memory of the gateway. And the upper PC can collect and monitor the data from the gateway. The upper PC can also give out control instruction to the protocol gateway to control the plc via the RS485 port. Many square solar cells. can connect to one same fiber optic ethernet switch. In this way thousands of solar-tracker can be controlled and monitored.
1. Haiwell H01TCP-4 gateway module’s networking capacity is very strong. Compared to the traditional networking ,the cost of haiwell connecting way is very low. One H01TCP-4 gateway module can monitor at least 60 sets of plc.
2. The H01TCP Gateway has Communication break alarm for all the slave plcs in the big network, very convenient compared to the traditional network management. It’s much easier than the traditional networking in troubleshooting and saves much time.
3. Haiwell PLC programming software has internal simulator inside, it reduces the programming time and debugging time. The analog input value can be the engineering value directly,needless to transform the engineering value to a middle value.