SOLAR_HYD_CTRL¶
| Available as of PLC runtime system: | V1.3 and above |
| Included in library: | Solar_AC500_V22.lib |
| Type | Function |
| Group | Package of functions to get the sun position |
Function Block to manage two pistons as actuator device.
- Hydraulic system to move the tracker.
Hydraulic system is based in the action of two hydraulic pistons (Piston A and Piston B) that are controlled by four solenoid valves. Each hydraulic piston has two solenoid valves to control its movement. These solenoid valves are two position valves.
A1: Backward piston A (piston A reduces its length).
A2: Forward piston A (piston A increases its length).
B1: Backward piston B (piston B reduces its length).
B2: Forward piston B (piston B increases its length).
Hydraulic system also has an oil pump to get pressure into the hydraulic circuit. This pumps works for a few periods of time, it doesnt work continuously.
Movement range of tracker [-30° - 181°]:
Movement cycle of the hydraulic pistons:
Movement Cycle of the Hydraulic Piston is the Following:
During a part of the movement cycle, both pistons are running in the same direction (both are pulling or pushing at the same time).
During a part of the movement cycle, one piston has reached its singular point. In this position, the piston does not generate any torque in the system.
During a part of the movement cycle, both pistons are running in opposite directions (one of them is pulling and the other one is pushing at the same time).
Graphic below shows the movement cycle of the hydraulic pistons:
X-axis represents the allowed position range of Solar Tracker (these values are configurable by the user).
Y-axis represents the length of the hydraulic pistons.
In this case, singular points are:
- Piston A: 49°.
- Piston B: 130°.
The singular point for piston A. Its value is ±2:
The singular point for piston B. Its value is ±1:
Movement Control:
To control the movement of the hydraulic pistons, it is necessary to operate on the solenoid valves. Depending on tracker position and direction of rotation, from east to west or from west to east, it is necessary to operate on determined solenoid valves.
Table below shows sequence of solenoid valves.
Where:
A1: backward piston A A2: forward piston A.
B1: backward piston B B2: forward piston B.
1: solenoid valve is ON 0: solenoid valve is OFF.
σ: free-window (degrees) ±: angular position of the Solar Tracker (degrees).
Note
All range position values that appear in the table above are configurable and depend on each tracker. A previous geometrical analysis is needed due to there are many kind of trackers. You can use this table as an example.