Real-time simulation based performance analysis of active filters for oil drilling rigs

In this paper performance analysis of active power filter (APF) is studied for oil drilling rigs through real-time simulation. A typical oil drilling rig consisting of adjustable speed drives powered by diesel engine generators is modelled and simulated. Conventional filters are not suitable for autonomous power systems as the system is not stiff bus system. APF are better suited for this application. Performance of filters can be tuned and assessed accurately if they are tested under actual operating conditions of the rig, particularly weak bus and dynamic loading characteristics. A real-time test procedure to experimentally test the performance of APF connected to a diesel generator and drive system is developed. Then the drives are loaded as per the data collected from rig over a drilling cycle and harmonic filtering performance of APF is studied. In this method, dynamic models of diesel engine, synchronous generator, AC/DC converter and DC drive are solved on a digital signal processor in real time and the solution is fed to current controller controlling a voltage source inverter to emulate the oil rig system. A physical shunt APF is then connected to the setup and its dynamic performance is evaluated while load is changing. Dynamic models of for all the components are presented and simplifications are suggested so as to reduce the computational need of processor. These models are validated through computer simulations by comparing with detailed models.