A review of utility issues for the integration of wind electric generators

A review of issues and concerns of the electric utility industry for the integration of wind electric generation is offered. The issues have been categorized in three major areas: planning, operations, and dynamic interaction. Representative studies have been chosen for each area to illustrate problems and to alleviate some concerns. The emphasis of this paper is on individual large wind turbines (WTs) and WT arrays for deployment at the bulk level in a utility system

Experimental investigation of a variable speed constant frequency electric generating system from a utility perspective

As efforts are accelerated to improve the overall capability and performance of wind electric systems, increased attention to variable speed configurations has developed. A number of potentially viable configurations have emerged. Various attributes of variable speed systems need to be carefully tested to evaluate their performance from the utility points of view. With this purpose, the NASA experimental variable speed constant frequency (VSCF) system has been tested. In order to determine the usefulness of these systems in utility applications, tests are required to resolve issues fundamental to electric utility systems. Legitimate questions exist regarding how variable speed generators will influence the performance of electric utility systems; therefore, tests from a utility perspective, have been performed on the VSCF system and an induction generator at an operating power level of 30 kW on a system rated at 200 kVA and 0.8 power factor

A conceptual framework for evaluating variable speed generator options for wind energy applications

Interest in variable speed generating technology has accelerated as greater emphasis on overall efficiency and superior dynamic and control properties in wind-electric generating systems are sought. This paper reviews variable speed technology options providing advantages and disadvantages of each. Furthermore, the dynamic properties of variable speed systems are contrasted with synchronous operation. Finally, control properties of variable speed systems are examined

The future for follow-up of gynaecological cancer in Europe. Summary of available data and overview of ongoing trials

After completing treatment, most patients follow a pre-determined schedule of regular hospital outpatient appointments, which includes clinical examinations, consultations and routine tests. After several years of surveillance, patients are transferred back to primary care. However, there is limited evidence to support the effectiveness and efficiency of this approach. This paper examines the current rationale and evidence base for hospital-based follow-up after treatment for gynaecological cancer. We investigate what alternative models of care have been formally evaluated and what research is currently in progress in Europe, in order to make tentative recommendations for a model of follow-up. The evidence base for traditional hospital based follow-up is limited. Alternative models have been reported for other cancer types but there are few evaluations of alternative approaches for gynaecological cancers. We identified five ongoing European studies; four were focused on endometrial cancer patients and one feasibility study included all gynaecological cancers. Only one study had reached the reporting stage. Alternative models included nurse-led telephone follow-up and comparisons of more intensive versus less intensive regimes. Outcomes included survival, quality of life, psychological morbidity, patient satisfaction and cost effectiveness of service. More work is needed on alternative strategies for all gynaecological cancer types. New models will be likely to include risk stratification with early discharge from secondary care for early stage disease with fast track access to specialist services for suspected cancer recurrence or other problems

Analysis Methodology for Industrial Load Profiles

A methodology is provided for evaluating the impact of various demand-side management (DSM) options on industrial customers. The basic approach uses customer metered load profile data as a basis for the customer load shape. DSM technologies are represented as load shapes and are used as a basis for altering the customers existing measured load shape. The impact of load shape changes on the customer is evaluated in terms of a change in the electric bill by using a software analytical tool called LOADEXPERT™. The software calculates the customer's bill for a particular rate structure and a given load shape. The output data from LOADEXPERT™ are used to calculate the rate of return on the DSM technology investment. Other uses of load profile data are provided

A new casting defect healing technology

A new technology is presented for healing of defects in 356 aluminium alloys that provides economic upgrading of these cast alloys. It uses pneumatic isostatic forging (PIF) to produce high quality Al alloys products with enhanced mechanical properties uniform throughout the part, allowing higher design allowables and increased usage of Al alloy castings. The fundamental mechanism underlying PIF is a single mode plastic deformation process that uses isostatic application of pressures for 10-30 seconds at temperature. The process can be integrated in-line with other production operations, i.e., using the latent heat from the previous casting step. Results of applying the PIF process indicate lower cost and significant improvement in mechanical properties that rival and often exceed corresponding properties of other technologies like hot isostatic pressing and related processes. This process offers many advantages that are described in this paper in addition to presenting case histories of property enhancement by PIF and the mechanism responsible for property enhancement

Electron spin resonance (ESR) investigation of the structure of methyl radical trapping sites in methanol glass

Measurements are reported of ESR spectra of methyl radicals trapped in methanol glasses. In these spectra, forbidden lines appear as satellites of the lines of the methyl quartet as a result of dipolar coupling of the unpaired electron with protons of neighboring methanol molecules. The relative intensity of the satellites is used to study the structure of the sites where the radicals are trapped. Comparison of intensities observed in CH3OH, CH 3OD, CHD2OD, CD3OH, and CD3OD indicates a structure that is locally similar to the (disordered) \u3b2-phase crystal structure of methanol, with the methyl radical replacing a methanol molecule and occupying a position close to its methyl position. The resulting methyl-methyl distances are compared with those deduced from the observed rate constants of the hydrogen abstraction reaction taking place at the trapping sites. If volume changes due to cooling and phase transitions are taken into account, the distances obtained in the two experiments are found to be compatible. This confirms earlier conclusions that methanol glass has many structural features in common with the \u3b2-phase crystal.Peer reviewed: YesNRC publication: Ye