Study on Simulation System of Relay Protection for Smart Substation

A simulation system of dynamic characteristics of relay protection based on smart substation was exploit in this paper. The necessary information was extracted form SCD configurations file of smart substation and fault recording document, the different frequency of sampled data was transformed and unified, the action process of relay protection equipment is simulated with operating equation and action characteristics which is advance defined or self-defined, the process from normal to fault is reappeared by graphics in this system. The system, which was opening and expansibility, was suitable for reproducing dynamic characteristics of protection in smart substation, also was applicable to develop new principle protection equipment.

An Intelligent Tool Post in a Lathe

An Intelligent Tool Post (ITP) used in lathe is proposed in this study. ITP is designed from the basis of two different cutting force characteristics produced from abnormal cutting generated by tool crashing workpiece and from normal cutting. ITP is capable of sensing and distinguishing the normal cutting signals from the abnormal ones. During normal cutting, ITP is able to resist the cutting torque and continue the cutting. As abnormal cutting occurs, the tool would move away from the workpiece without any damage. The equations for design and operation have been established. With the threshold and the design equation, one can design appropriate ITP. The threshold can be calculated and set up by the operating equation and the cutting conditions. Furthermore, Taguchi method was employed to conduct the experiments and analyze the experimental results. The results showed that the ITP’s functions met the design requirements completely.

A New Device for Field Recovery of Barite: II. Scale-Up and Design

Earlier work on a mud separator for barite recovery is extended to the design and construction of a rugged field unit. Problems associated with scale-up for field use include the use of dilution water and its effect on capacity, power requirements and pressures developed. Equations for these quantities are derived and applied in maximizing the beneficial effects of dilution and minimizing the power required. Tests on the full-size rotor show that its performance can be predicted by theory. The completed unit is compact and lighter than current decanting types. Its capacity is from 10 to 22 gal/min with corresponding barite recovery efficiencies of 92 to 86 per cent. Introduction In an earlier publication a new type of centrifugal device was described for solid-liquid separations. In that paper an operating equation was derived, and its validity demonstrated in laboratory scale experimentation. Some of the features apparent in this new device seem particularly well suited to the conservation of barite in field drilling-mud systems, hence the development was extended to the design and construction of a field unit. In the present paper the design problems associated with scale-up are considered. A full-scale, rugged, self-contained field unit is described, and test results discussed which verify that the performance of the large field unit can be described by a simple operating equation. PRINCIPLE OF OPERATION OF SEPARATOR In principle, the new device is simply a perforated cylinder rotating within a body of fluid which is contained within a stationary case, as in Fig. 1. The frictional drag generated by the rotating cylinder causes part of the fluid to rotate. At the surface of the cylinder, assuming no slip occurs, the angular velocity of fluid and of the cylinder are identical. if there are suspended particles present of greater density than the fluid, the centrifugal force acting on these particles causes them to move radially away from the cylinder at some velocity, vp. Where the Stokes settling equation holds, this velocity may be expressed as: ....................(1) If the case is provided with openings at both ends, a suspension can be pumped in at one end at a fixed rate. Part of the suspension can then be removed at a fixed rate at the other end of the case as underflow, and the remainder forced through the perforations and hollow shaft of the rotor to appear as effluent, also at a fixed rate. the radial component of the flow velocity of this stream as it reaches the rotor surface, is simply effluent flow rate divided by cylindrical surface area: ....................(2) Because vp is a function of particle size, for some particular particle size, the velocities vp and vr will be equal in magnitude. This is defined as the critical particle size and represents the size above which all particles appear in the underflow and below which all particles appear in the effluent. SPEJ P. 100ˆ

A New Device for Field Recovery of Barite From Drilling Mud: I. Theory and Laboratory Results

The inadequate use of centrifugation to economically recover solids from weighted drilling fluids reflects the need for better equipment and techniques for this purpose. Laboratory studies in the development of an improved separator are described in which an operating equation is derived and tested. Results show that the concentric cylinder geometry employed effectively separates barite from a suspension and that the operating equation provides a good approximation for scale-up. Introduction Our current drilling technology frequently requires a high-density drilling fluid obtained by addition of barite. In the course of drilling, formation solids which are too fine to be removed either by screening or settling become suspended in the drilling fluid and gradually the volume of solids in the mud increases. The volume fraction of solids must be limited (if a satisfactory set of rheological parameters are to be maintained). A centrifugal separator provides an economical way of accomplishing this. The barite recovery process can be considered as a separation of two solids. One, the light solids, composed of formation and added solids, has a specific gravity of 2.6 to 2.7; the other, barite, has a specific gravity of 4.2 to 4.3. This density difference, plus the fact that the average light-solids particle size is much smaller than the average barite particle size, permits separation by a centrifuge. In drilling fluids some of the coarse particles of the light-solids-range will settle faster than fine particles of the barite-particle range. As a result a complete separation of the two species is not possible. Since the object of the process is not merely recovering the maximum amount of barite but includes as well removing the maximum amount of light solids, an optimum barite recovery efficiency exists. From a practical standpoint this optimum cannot be determined in the field for each drilling fluid system, and in practice the separation is less than optimum, with some sacrifice of barite. Drilling technology has included centrifugal separators for barite recovery for more than a decade. Results have been reported by a number of investigators indicating that the process is practical and economical. The decision to use a centrifuge is based on economics in which direct cost savings and the indirect benefits in rig time derived from improvement of the drilling fluid are important factors. One would expect that centrifugal separation of barite from drilling fluids would significantly affect barite consumption; however, this is not the case. The Minerals Yearbook shows an annual domestic barite consumption in the drilling industry of nearly I million tons. By rough estimate there are perhaps 80 separators presently in field use. Assuming half of these in use at any one time, operating an, average of four hours per day, at recovery rates averaging 3,000 lb of barite per hour, total annual recovery is about 90,000 tons. This is less than 10 per cent of the total barite used. I conservatively estimate that barite consumption in drilling operations can be reduced by 30 per cent through greater utilization of centrifugal separators. To encourage more wide- spread acceptance of centrifugal separators in the drilling industry, improved equipment and techniques would be very desirable. The present paper, covering theory and results obtained from a laboratory model, is the first in a series on the development of an improved mud separator for field use. THE CONCENTRIC CYLINDER GEOMETRY AS A SEPARATING DEVICE Consider the geometry shown in Fig. 1, consisting of two concentric cylinders separated by an annular space. These are arranged so that the outer cylinder is fixed and the inner one can be rotated about its axis on shafts sealed against the ends of the outer cylinder. SPEJ P. 6ˆ