Search

A high frequency electromechanical energy conversion option for space power applications is introduced. An induction generator (IG) operating at high frequencies is an excellent option for obtaining high power and energy densities. Various design aspects affect the operating characteristics of the machine. The effects and consequences of specific trade-offs in the design process are explored. The methodology is helpful in evaluating specific choices for materials as well as machine configurations. Use of power semiconductor devices and other power electronic devices is avoided to provide immunity from radiation and electromagnetic interference.

The amount of reactive reserves at generating stations is a measure of the degree of voltage stability. With this perspective, an optimized reactive reserve management scheme based on the optimal power flow is proposed. Detailed models of generator limiters, such as those for armature and field current limiting must be considered in order to utilize the maximum reactive power capability of generators, so as to meet reactive power demands during voltage emergencies. Participation factors for each generator in the management scheme are predetermined based on the voltage-var (V-Q) curve methodology. The Bender's decomposition methodology is applied to the reactive reserve management problem. The resulting effective reserves and the impact on voltage stability are studied on a reduced Western Electric Coordinating Council system. Results prove that the proposed method can improve both static and dynamic voltage stability. Index Terms--Bender's decomposition methodology, optimal power flow, reactive power management, voltage collapse.

Three well-known and widely accepted concepts in educational psychology are revisited. These are 'inventory of learning styles,' 'taxonomy of educational objectives,' and 'metacognition.' Relationships among these concepts are highlighted. Often, a student can develop his (or her) own learning style by the process of metacognition. Ideas are borrowed from these concepts for use in a first-level power systems course. It is beyond a doubt that both cognitive and metacognitive skills are necessary for students to succeed in any course. While a semester-long power systems course leaves little time for critical thinking and passive reflection for students, certain activities may very well serve for some of these learning processes. Index Terms--Bloom's taxonomy, educational objectives, inventory of learning styles, metacognition.

A new method for security-constrained corrective rescheduling of real power using the Hopfield neural network is presented. The proposed method is based on solution of a set of differential equations obtained from transformation of an energy function. Results from this work are compared with the results from a method based on dual linear programming formulation of the optimal corrective rescheduling. The minimum deviations in real power generations and loads at buses are combined to form the objective function for optimization. Inclusion of inequality constraints on active line flow limits and equality constraint on real power generation load balance assures a solution representing a secure system. Transmission losses are also taken into account in the constraint function. Keywords: Feedback ANN, Real power optimal dispatch, corrective strategy, security enhancement.

A photovoltaic-powered water pumping project comprising of several rural electric cooperatives and their customers is described in detail. A number of remote water pumping installations in the state of Wyoming are currently operating as a result of this project. The design, installation and performance monitoring of these systems are discussed. In general, it can be stated that PV-powered water pumping in this state, has been a cost-effective alternative to distribution line extension or other conventional means of water pumping. Customer satisfaction, in terms of functional adequacy and low maintenance requirements of these systems, is high. The benefit for the utilities concerned, are cost savings and better customer relations.

A graphics-oriented, primarily PC-based tool for education, research and training in power engineering is introduced. The tool called COPERITE has all user interfaces resident on an 'IBM-386' microcomputer. Menus and windows are used generously for the interface and attractive graphical representations and displays are used. Application programs that are interfaced are power flow, contingency analysis, economic dispatch, security-constrained dispatch, system stability and fault analysis. These programs are executed on a VAX 8800 computer mainly for speed of execution. Information exchange between the PC and the VAX is made through an ethernet connection which is transparent to the user. Results of execution show up on the graphical front-end accessible to the user. COPERITE has a powerful network editor having the capabilities of adding, deleting, moving and finding symbols with a graphics cursor. Provisions are present for building and using artificial intelligence techniques for system operation enhancement.

Several analysis methods are available for long-term voltage stability. The V-Q curve power flow method is widely used by Western Systems Coordinating Council utilities, and has some advantages. Long-term dynamic simulation with proper modeling, however, is clearly the most accurate simulation method. We compare the two methods for wintertime voltage stability problems in the Portland, Oregon USA load area. Results from the V-Q method can be misleading. The same is true of other power flow program based analysis employing conventional modeling. Results from these, power flow methods may be pessimistic, causing overdesign or overly conservative operation. Index Terms--Long-term dynamic simulation, power flow simulation, voltage collapse, voltage stability.

The amount of reactive reserves at generating stations is a measure of the degree of voltage stability. With this perspective, an optimized reactive reserve management scheme based on the optimal power flow is proposed. Detailed models of generator limiters, such as those for armature and field current limiting must be considered in order to utilize the maximum reactive power capability of generators, so as to meet reactive power demands during voltage emergencies. Participation factors for each generator in the management scheme are predetermined based on the voltage-var (V-Q) curve methodology. The Bender's decomposition methodology is applied to the reactive reserve management problem. The resulting effective reserves and the impact on voltage stability are studied On a reduced Western Electric Coordinating Council systems Results prove that the proposed method can improve both static and dynamic voltage stability. [ABSTRACT FROM AUTHOR]