摘要:

This paper is concerned with the use of electromagnetic linear actuators for the suspension and position control of the cast-iron seals employed in large regenerative air preheaters. The function and operation of power-station air preheaters are discussed and the problems arising from differential expansion and thermal distortion in the large steel structures are explained. A solution for seal-wear and air-to-gas leakage, using a composite magnet/spring suspension system, is presented and the design, construction, supply and control of suitable electromagnets are described. Particular attention is paid to the problems posed by the extreme severity of the working environment during both design and operation of the electrical equipment. The paper concludes with attempts to assess the effectiveness of the modified seal suspension system and to quantify the benefits which might be expected as a result of improved preheater performance.

DOI:10.1049/ip-c.1987.0001

出版商:IEE    

年代:1987

数据来源: IET

摘要:

Failure events originating in terminal stations can result in multiple outages of generators and/or lines or loads in a power system. Failures of breakers, transformers and busbar sections are major causes of these multiple outages. The effect of these outages in composite-system reliability evaluation can be quite significant. The effect of station-related multiple outages can be quite dominant and may, therefore, obviate the need to consider higher-order independent outages of major components such as generating units, transmission lines and transformers. In this paper, models are presented and discussed for various possible failure events originating in the stations. Expressions in terms of probability and frequency of appropriate states are developed for each of the failure events. These expressions are then utilised in the adequacy assessment of a composite 6 busbar test system.

DOI:10.1049/ip-c.1987.0002

出版商:IEE    

年代:1987

数据来源: IET

摘要:

Adequacy evaluation of a composite power system normally only considers independent outages of elements such as generating units and transmission lines/transformers. The adequacy indices are calculated after examining a predetermined sequence of outage events. The computation time increases tremendously, if the number of outage events is large. It may be possible to avoid examining high-level contingencies in relatively small power-system networks. As the size of the system increases, testing of higher-level simultaneous independent outages, particularly those of generating units, becomes an important factor. The computation time increases tremendously as the system size increases because of both the number of outages that are to be examined and the time required to solve the network under each outage situation. It becomes important therefore to appreciate the effect of contingency level selection on the calculated adequacy indices. This paper illustrates the effect of including higher-level outages on the adequacy of three power systems, a small hypothetical 6-busbars test system, the standard IEEE Reliability Test System (RTS) and a model of the existing power-system network of the Saskatchewan Power Corporation in Canada.

DOI:10.1049/ip-c.1987.0003

出版商:IEE    

年代:1987

数据来源: IET

摘要:

The steady-state and dynamic simulation models currently proposed for the derivation of AC/DC system waveforms are described. Their application to the prediction of harmonic distortion is compared with reference to accuracy, general applicability and computational efficiency. It is concluded that generally the use of an iterative steady-state algorithm provides the most accurate and efficient solution. However, such an algorithm often presents convergence problems and in such cases dynamic simulation provides the necessary back up to obtain a solution.

DOI:10.1049/ip-c.1987.0005

出版商:IEE    

年代:1987

数据来源: IET

摘要:

A simplified analysis of the effect of a static reactive-power (VAr) compensator (SVC) on the stability of a two-machine system is presented. This analysis shows that the SVC's damping effectiveness is greatly affected by a self-feedback term, whereby a change in SVC suceptance changes the measurement signal which is used to control the SVC. Recognition of this term explains why some control signals are superior to others, and why an SVC might offer limited damping improvement, even with a high-gain damping control. Results of a transient simulation are presented which show that, with a suitable control and a suitable location, an SVC can offer a marked improvement to the damping of rotor-angle oscillations in a power system. The high effectiveness of the SVC in rapidly changing the power flow makes the correct control decision essential during the fault period; guidelines for the control strategy during the fault are presented.

DOI:10.1049/ip-c.1987.0006

出版商:IEE    

年代:1987

数据来源: IET

摘要:

Improved mathematical models of transmission lines are used to develop a fault location method which copes with high-frequency transients. The telegraph equations used for a line model are solved by the method of characteristics using voltage and current samples as boundary conditions taken at one end of the line within the first few milliseconds of fault inception. Estimates of voltage and current profiles for the entire length of the transmission line during the fault are obtained. Criteria for fault location are based on a formulation involving these voltage and current estimates. For fault location on multiphase systems the concept of modal analysis is used in enhancing the fault-locating capability of this algorithm.

DOI:10.1049/ip-c.1987.0007

出版商:IEE    

年代:1987

数据来源: IET

摘要:

BC Hydro's Cathedral Square substation is a major 230/12 kV underground station in the heart of downtown Vancouver. The civil design of the substation, including site investigation, excavation, structural design and construction, is described. In addition, the mechanical design is described covering fire protection systems, station drainage, sewage and water supply, cooling systems and heating ventilation and air-conditioning and a unique transformer handling system. The electrical design of the substation is the subject of two companion papers.

DOI:10.1049/ip-c.1987.0009

出版商:IEE    

年代:1987

数据来源: IET

摘要:

Cathedral Square substation is a major 230/12 kV underground substation in the heart of downtown Vancouver. The 230 kV electrical design incorporates a number of unique features and is described in this paper. The civil, mechanical and related electrical design features of the substation are described in companion papers [1, 2].

DOI:10.1049/ip-c.1987.0010

出版商:IEE    

年代:1987

数据来源: IET

摘要:

Cathedral Square substation is a major 230/12 kV underground substation in the heart of downtown Vancouver. The 12 kV electrical, station-service, grounding, protection and control and fire-detection design features are described in this paper. The civil, mechanical and other related electrical design features are described in companion papers [1, 2].

DOI:10.1049/ip-c.1987.0011

出版商:IEE    

年代:1987

数据来源: IET

摘要:

The paper presents the results of the analysis of the main HV/MV(LV) substation earthing system parameters. Typical parallel driven four- and three-rod earth electrodes are analysed, including the effects of the horizontal, connecting conductors. The influence of metallic objects buried in close proximity to the earth electrodes on the main system characteristics and on the transferred potential is also studied. The results are presented in a generalised form, and can be used in practical design.

DOI:10.1049/ip-c.1987.0012

出版商:IEE    

年代:1987

数据来源: IET