A case study of electro-hydraulic loading and testing technology for composite insulators based on iterative learning control

In order to simulate the vibrating condition of composite insulators in breeze, and carry out its fatigue test under loading and vibrating conditions, the electro-hydraulic loading and testing technology for the composite insulators is researched in this study. A compound electro-hydraulic loading system is first designed, including two subsystems, the static proportional loading system and the dynamic servo loading system. Then, the working principle based on this system is analyzed, and the mathematic model of electro-hydraulic servo system is also built, proved to be an inertial element with high gain. The control method based on proportional-derivative-type iterative learning control has been applied to such a dynamic servo loading system, to achieve the high-precision control for dynamic load force with repetitive regularity. Both mathematic simulation and actual experiments have been designed and carried out, and their results proved that the load principle and the control method are feasible and applicable and have the ability of achieving high-precision control effects. Based on this discussed electro-hydraulic technology, an actual electro-hydraulic loading and testing system for different kinds of composite insulators has been researched and developed, with the advanced technology indices of six loading channels, 20kN maximum dynamic force, 0.3kN force control precision and 100 Hz maximum vibrating frequency.