模糊支持向量机在轴系振动故障诊断中的应用

机组的振动水平是表征电厂稳定安全最重要的标志之一.本文利用支持向量机的智能方法对机组的轴系故障进行诊断,在小样本集上取得了100%的分类精度.在此基础上,还引入部分噪声数据,统计其分类性能,展示了支持向量机的容错能力.最后分析了支持向量机方法在轴系振动故障振动的优势和缺陷,引入模糊输出支持向量机进行了改进,给设备维修提供了更多的参考信息.     

Finite-element calculation of leakage inductances of a saturated salient-pole synchronous machine with damper circuits

It is important to understand the relationship between leakage flux distributions and machine characteristics for better design of synchronous machines. This paper presents a calculation method for leakage inductances of saturated salient-pole machines with damper circuits. All leakage inductances are divided into the self-leakage, gap leakage, and winding-differential leakage inductances. The leakage inductances correspond directly to the leakage flux distributions in the machines. Cross-magnetizing inductances are also calculated. The method is applied to a 300-MVA class generator. The relationship between the winding distributions, flux distributions, saturation, and inductances is discussed. Weak magnetic influence of the damper circuits on the armature in the d-axis is quantitatively illustrated through values of the winding-differential leakage inductances. The cross-magnetizing inductances, except for the d-axis damper circuits, are relatively large. Variations of the armature self-leakage inductances with saturation are small, and variations of the field and damper self-leakage inductances are larger.     

Interfacing wind energy conversion equipment with utility systems

Technical interface issues between utility systems and solar technology devices are receiving increasing attention from government and industry. These issues arise from the intermittent power generation characteristics of solar systems, in contrast to most utility generation equipment. This paper explores the interface issues for wind energy systems, a solar technology likely to achieve early commercialization. Described are government- and industry-sponsored assessments of the impact of wind energy devices on industry operations, controls, and protective subsystems. The conclusions drawn indicate that: there does not appear to be any major technical interface problem in applying wind energy devices to utility power systems; current utility control and protection design methods are adequate for interfacing wind energy units with a utility system; and, the cost of control and protection for large (over 1 Mw) wind machines appears acceptable but may prove prohibitive for small machines. Several advanced technology options with the potential for reducing the costs for protection and control are also described, for both the wind machines and the utility system.     

Minimum/maximum excitation limiter performance goals for smallgeneration

Small generators connected to the electric utility system often act as followers as they tend to follow power system bus voltage variations. For the lack of kVA capacity, small machines tend to be susceptible to becoming over or underexcited (excessive VArs in or VArs out of the generator) as the voltage regulator tries to maintain its setpoint with variations in system bus voltage. Minimum and maximum excitation limiters are utilized to limit the voltage regulator characteristic response to system bus voltage changes, that can otherwise result in machine overheating and/or pulling out of synchronization. This paper reviews the operating performance of minimum and maximum excitation limiters used on small machines, and provide the user typical performance expectations. The examples shown by the authors highlight both main field and exciter field applications     

ZR176型柴油机的研制

在ZR系列柴油机基础上扩缸、改变行程、提高功率,并保持结构紧凑、质量轻的特点以匹配小型机具。     

The development and testing of a heat pump for heating a single room

A small through-the-wall heat pump unit has been developed and tested to provide information on the problems associated with such machines. It is an air-to-air heat pump based on refrigeration components and is designed to supply sufficient heat for one room of a dwelling. the evaluation has been carried out in an experimental test facility built specifically to handle air source heat pumps.     

Design and construction of a single phase claw pole permanent magnet motor using composite magnetic material

To investigate the application of composite magnetic materials in electrical machines, a small single phase claw pole permanent magnet motor using soft material as the stator core has been designed and constructed. Based on the three-dimensional magnetic field analysis, the induced stator emf, cogging torque, and the steady state motor performance when operated as a synchronous motor are predicted.     

A method for integrated extraction of logging residues and soil scarification on a small scale

A new method for integrated haulage of logging residues and soil scarification on a small-scale has been evaluated. The base machine was a farm tractor to which a grapple loader trailer was attached. The grapple loader had an attachment on the grapple used for the integrated recovery of forest energy from logging residues and soil scarification. The machine was in this case, when hauling the logging residues fresh, also used for hauling round wood. It may even be used for, e.g. spreading wood ashes (only simulated). Conventional machine systems with special machines for all four types of work result in very high fixed costs for moving, etc. which makes cost unacceptable for many small sites.

Effective time per dry ton of logging residues was 28.4 min in the integrated method, of which soil scarification was 14.3 min. Average load size was about 1.3 ton dry matter (about 2.9 m³ solid). The soil scarification plots covered 12% of the surface.

Cost calculations show that the integration of several activities results in substantially lower costs for small harvesting sites. For sites of about 1.5 ha the cost is about the same as for conventional machines. The studied method creates new possibilities for self-employed forest owners to do the work themselves and, in case of lower personal cost and no moving cost, reduce cost further.     

Design and construction of a simple blade pitch measurement system for small wind turbines

For small wind turbines to be reliable they must have in place good mechanisms to protect themselves against very high winds or sudden removal of load. One common protection method in small wind turbines is that of blade feathering. It is important that the blade feathering mechanism of a small wind turbine is tested before the turbine is installed in the field. This paper presents a simple system for monitoring the blade feathering of a turbine with an overall component cost that small wind turbine manufacturers can afford. The Blade Pitch Measurement System (BPMS) has been designed and constructed by the Research Institute of Sustainable Energy (RISE) and aids small wind turbine manufacturers in testing and optimising the settings of the blade feathering mechanisms on their machines. The results show that the BPMS was successful in recording the behaviour of the blade feathering mechanism in field trials with a 20 kW and a 30 kW wind turbine. The BPMS displays significant potential as an effective, inexpensive system for small wind turbine manufacturers to ensure the reliability of their pitch regulating over-speed protection mechanisms.     

Optimum hot water temperature for absorption solar cooling

The hot water temperature that maximizes the overall instantaneous efficiency of a solar cooling facility is determined. A modified characteristic equation model is used and applied to single-effect lithium bromide-water absorption chillers. This model is based on the characteristic temperature difference and serves to empirically calculate the performance of real chillers. This paper provides an explicit equation for the optimum temperature of vapor generation, in terms of only the external temperatures of the chiller. The additional data required are the four performance parameters of the chiller and essentially a modified stagnation temperature from the detailed model of the thermal collector operation. This paper presents and discusses the results for small capacity machines for air conditioning of homes and small buildings. The discussion highlights the influence of the relevant parameters.     

浅谈风幕机节能小改造

通过现场调研及对风幕机工作要求的探索,从节能要求方面提出对风幕机控制方面改造的节能措施,达到降耗节能的目的。尤其适用于风幕机间断工作的场所,具有明显的节能效果。     

Standstill frequency-response methods and salient-pole synchronousmachines

Standstill frequency-response (SSFR) literature to date has primarily focused on turbo-alternators, which have a double-cylindrical topology. Synchronous machines driven by hydraulic turbines or internal combustion engines are salient-pole machines whose electrical constants are somewhat different due to construction differences: (1) the salient-pole topology produces a ratio of L_q/L_d of approximately 0.5 as opposed to unity for cylindrical-rotor machines; (2) the salient poles are constructed of steel-sheet stampings rather than forged steel; (3) salient-pole field windings are concentric whereas those of cylindrical rotor machines are distributed; (4) salient-pole generators often have amortisseur windings embedded in the pole faces; and (5) fractional slot/pole/phase (SPPP) stator windings are commonly employed in salient-pole machines whereas turbo-alternators are more apt to be limited to integral SPPP windings. These differences alter time constants, inductances, and transfer functions. This paper provides needed information for the modeling of salient-pole machines for use in simulation studies using a theoretical approach     

Axial-Field Electrical Machines - Design and Applications

Axial-field electrical machines offer an alternative to the conventional machines. In the axial-field machine, the airgap flux is axial in direction and the active current carrying conductors are radially positioned. This paper presents the design characteristics, special features, manufacturing aspects and potential applications for axial-field electrical machines. The experimental results from several prototypes, including d.c. machines, synchronous machines and single-phase machines are given. The special features of the axial-field machine, such as its planar and adjustable airgap, flat shape, ease of diversification, etc., enable axial-field machines to have distinct advantages over conventional machines in certain applications, especially in special-purpose applications.     

Residue recovery and site preparation in a single operation in regeneration areas

The integration of logging residue extraction, along with the establishment of a new stand and soil preparation is a new idea. A dual-purpose machine has been developed in Finland. It can be used as both a scarifier and a slash forwarder without the need for time-consuming conversion work. According to research results, the machine has proved to be rather competitive. In average conditions, the integration decreases the cost of scarification and residue recovery by about 10%, when compared to separate operations with two machines. Slash forwarder–scarifier is ideally suited for use in small regeneration areas, where the costs of moving two separate machines between sites would constitute a large share of the total costs. By the slash forwarder–scarifier operators exposure to the whole body vibration during the work decreases due to slower driving speed, the machine's greater weight and the position of scarifying plates in the middle of the machine body.     

Methods for determining the intermediate-axis saturation Characteristics of salient-pole synchronous Machines from the measured D-axis Characteristics

In the analysis of the steady-state performances of saturated synchronous machines using the classical two-axis (d- and q-axis) frame model, the accurate calculation of the machine performances depends to a large extent on their saturation conditions. However, the effect of saturation depends not only on the saturation level in the axis of the resultant machine ampere-turns (intermediate-axis) but also on the phase angle between the resultant ampere-turns and the resultant magnetic flux. This work presents four analytical methods for determining the intermediate-axis saturation characteristics of salient-pole synchronous machines from the measured d-axis saturation characteristics. The accuracies of these four methods have been verified by comparing the measured field currents and load angles of two laboratory salient-pole synchronous machines of different designs with those calculated using an innovated approach which uses the intermediate-axis saturation characteristics directly in the modeling of the saturated synchronous machines. Moreover, the calculated intermediate-axis saturation characteristics have been compared with the measurable ones in the case of one of these machines.     

Comparison between analytical and numerical methods of calculatingtooth ripple losses in salient pole synchronous machines

The application of analytical and numerical methods to an electromagnetic problem requiring an accurate representation of saturation is examined. The problem considered is that of tooth-ripple losses in salient-pole synchronous machines for the situation where the pole pitch is much greater than the armature slot pitch so that the applied DC field can be taken as uniform. To calculate these losses, several analytical methods have been developed over a period of many years. Two such methods, one devised by Oberretl (1972) and a modified version of the considerably older one-dimensional approach of Gibbs (1947), are compared with results obtained from the finite-element and finite-difference methods. Using a time-stepping finite-difference calculation, the influence of moving boundaries and the imposed DC field are taken into account for the first time in this tooth-ripple calculation. A saturation factor is defined that allows the designer to calculate the tooth-ripple losses of solid salient-pole synchronous machines for a wide range of machine size taking magnetic saturation into account. To verify the theory, the results are compared with measurements on a small model. These measurements were done using a torque meter placed between the model and a DC drive motor and were cross-checked by the Poynting vector method. Rules and limits are given for the use of the analytical methods     

Two step three time scale reduction of doubly fed machine models

A three time scale reduction method is presented, which consists of two successive two time scale seductions. The advantage is that only small order systems of equations are dealt with. This method is applied to doubly fed synchronous machines, and is compared with other methods. A discussion of the dynamic behavior according to inertia and operating point is also included     

Design of helical coil condenser of small-capacity Water/Lithium Bromide absorption cooling machine

Absorption machines are considered as a good alternative to vapor compression systems in terms of energy efficiency and environmental impacts. However, they use undeveloped resources (industrial waste heat …) and renewable energy (solar energy …) as primary energy sources. These considerations focus on the intent of the market on small-capacity absorption machines for domestic applications. The major problem of absorption machines is the high investment cost, which is mainly due to the prices of different components of the machine. In fact, the current machines implement shell and tube heat exchangers, which are largely incompatible with small-capacity compact machines. In this context, we are interested in the study and the development of a falling film compact condenser which allows meeting these expectations and developing domestic absorption machines. This work aimed to size a new type of a falling film helical coil condenser used in an absorption machine operating with the couple water/Lithium Bromide (H₂O/LiBr) and delivering a thermal power of 10 kW. It also presents a literature review on the transfer phenomena which react during the falling film condensation and various types and modes of condensation. A dimensioning model of helical coil condenser, based on the equations and the empirical correlations of heat transfer, was developed. The proposed configuration of the helical coil condenser has a great potential because of its compact size and the minimal weight for the design of our H₂O/LiBr machine for domestic applications.     

Affinity thermal machines and metallic salt-ammonia-ammoniates systems

The advantages and drawbacks of using monovariant metallic salt-ammonia-ammoniates systems in affinity thermal machines are discussed. These systems might be processed in machines of simple technology especially for solar cooling, heating and energy storage, on a household or industrial scale.     

Modelling of magnetic saturation in smooth air-gap synchronousmachines

Main flux saturation in d-q axis representation of synchronous machines is at present modelled by selecting either all the winding currents or all the winding flux linkages as state-space variables. However, these two available models are just a tiny portion of the complete set of models that can be obtained by selecting other combinations of state-space variables. This paper presents a general procedure for main flux saturation modelling in smooth air-gap synchronous machines, that is applicable for most selections of state-space variables. The method relies on the concept of `generalised flux' and `generalised inductance', that has been successfully applied in modelling of saturated single-cage and double-cage induction machines. The concept is extended to saturation modelling in smooth air-gap synchronous machines. A number of models, that result from the application of the method for different selections of state-space variables, are presented in detail