G.L. van Harmelen

A control system for optimizing deep hole drilling conditions

An instrumentation and control system has been designed for monitoring and controlling the parameters which determine the performance of a deep hole diamond drill. Bit performance in terms of average penetration rate and life has become extremely important because time-dependent costs have become the major proportion of the total costs per meter drilled due to the deep holes encountered especially in the gold exploration drilling industry. The authors define and discuss the important parameters influencing the drill bit performance. An analysis and simulation done on an assumed model indicated that stable, well-damped, closed-loop control could be maintained over the wide range of system dynamics expected to be encountered in the system. The results obtained so far in terms of the average penetration rate are very promising compared with results obtained prior to implementing the instrumentation and control system. Preliminary results indicate average penetration rates up to 100 m for a 24-h period compared to previous rates of some 50 m for the same period.<<ETX>>

Adaptive control of a TCR for hybrid compensators using the energy distribution optimization approach

An energy related approach for the interpretation and subsequent compensation of electrical power networks is introduced. It is proposed that optimum supply utilization is brought about by the correct time distribution of the energy drawn from the source and supplied to a load. Hybrid compensators are proposed in order to perform cost-effective energy redistribution between the source, the load, and the compensators. A time-domain-based digital adaptive control technique for TCRs (thyristor controlled reactors) in such a compensation system is described. An optimum reactive current is calculated in the time domain, and a linear extrapolation predictor is further implemented in real time to estimate future values of the firing angles for the thyristors. This feature is implemented in order to improve the dynamic response of the system for changing load conditions.<<ETX>>

The Modelling and Control of a Deep Hole Drilling Rig

Abstract Drill bit performance in terms of average penetration rate and life has become extremely important because time dependant costs have become the major proportion of the total costs per meter drilled, due to the deep holes encountered, especially in the gold exploration drilling industry. This paper gives an overview of the important parameters influencing the drill bit performance. An instrumentation and control system has been implemented for controlling these parameters. An analysis and simulation done on an assumed model indicated that stable, well damped, closed loop control could be maintained over the wide range of system dynamics which were expected to be encountered in the system. Practical observational results agree well with the results obtained by the simulation.

Measuring group geyser consumption patterns with a single water heater and a PC-based measurement and control system

A PC-based measurement and control system, connected to a single geyser, is proposed as a hardware based calculation technique in order to experimentally determine the relationship between water and electrical consumption patterns for a large number of users. Under the assumption that the thermostatic controllers present on the geysers deliver an average controlled temperature, the controller set-point (target) is set to that average value. Either the electrical usage pattern (controlled via a phase-controlled triac) or the water usage pattern (controlled via a PWM modulated water control valve) are fed as disturbances to this control system. The controller then varies the opposite parameter (water or electrical energy) in order to keep the temperature constant. This controlled input variable, in conjunction with the disturbance variable, deliver the required correlation between the water and electrical usage patterns as functions of time.<<ETX>>

Intelligent static VAr compensator control for supply loading optimization

A digitally adaptive static Var compensator (SVC) controller for supply-side loading minimization is proposed. The control scheme is based on a model reference control structure where a model (which includes its nonlinear behavior) for the thyristor controller reactor is present within the digital signal processor. This allows minimization software to use time-domain samples of three-phase line voltages and load currents to minimize the supply side loading (i.e., maximize power factor). This type of control uses the minimization of a cost function and therefore this same controller automatically also compensates for imbalance in a multiphase supply.

Real-time, dynamic controller for dynamic power filters in supplies with high contamination

A real-time, closed-loop controller system for controlling active power compensators under rapidly varying load conditions is proposed. With the aid of a dedicated signal processor, using correlation algorithms, real-time, analog compensation reference signals for dynamic power compensators are generated. In order to facilitate a cost-effective compensation system, separate compensation of the fundamental reactive power component and the harmonic components is further proposed. An algorithm time of 312 mu s in a 50 Hz system is achieved, providing an effective controller system bandwidth of 1.6 kHz.<<ETX>>

Power measurements in power systems using a personal computer

The need and operational criteria for an instrument capable of performing time-domain electrical power analysis are investigated and justified. The instrument is linked to a host personal computer, which performs the signal processing and mathematical analysis. This time-domain correlation technique can be used to analyze the different power components in power networks and calculate the effects of distortion. Effective compensation of polluted power systems can be designed using this instrument. Practical results have shown the excellent online operational characteristics of this measurement system, with excellent accuracy being obtained in both the time and the frequency domains.<<ETX>>