The need for comprehensive transient analysis of distribution systems

Abstract

Many surge analysis and design rules have evolved over time to help utilities cope with the complexity of transient phenomena. These rules have been widely applied to simplify analysis by restricting both the number and difficulty of the transient cases that need to be evaluated. On further reflection, however, the implicit assumption that elementary and conservative rules are a valid basis for design has often been shown to be questionable and sometimes dangerous. Indeed, many published guidelines are so misleading and so frequently false that they should only be used with extreme caution, if at all. This article specifically reviews a number of guidelines or suggestions found in various AWWA publications for water hammer analysis and provides a set of warnings about the misunderstandings and dangers that can arise from such simplifications. The authors conclude that only systematic and informed water hammer analysis can be expected to resolve complex transient characterizations and adequately protect distribution systems from the vagaries and challenges of rapid transients.

Piece‐wise mixed integer programming for optimal sizing of surge control devices in water distribution systems

“…Appropriate simulation time is a complex parameter that depends on event duration (e.g., valve closure time), wave speed, system length and configuration [Jung et al, 2007]. It is important to mention that proper protection with surge tanks reduces the pressure amplitude, and moves the maximum pressure peak further in time.…”

“…Jung and Karney expressed the similar concerns about useless or even harmful outcomes from the improper siting of SCDs [Jung and Karney, 2003]. More recently, Jung et al [2007] questioned the reliability of design rules and engineering guidelines regarding transients. They suggested that systematically examining the phenomenon is the only means to adequately protect distribution systems.…”

Effect of pressure‐sensitive demand on surge analysis

“…The potential surge aV / g is inaccurate in certain cases and thus is likely to lead to poor design. The inadequacies of this simplistic modeling approach for surge analysis have been described in detail (Jung et al, 2007a). Of interest is the fact that the maximum positive surge of the pressure‐sensitive demand model at junction 5 (26.1 m [85.5 ft]) was almost the same as the potential surge.…”

Comparative study of instantaneous frequency based methods for leak detection in pipeline networks

“…It also indicates the hydrant 3 (H3) and junction 2 (J2) with a very small amplitude peak and fails to locate the other features in the pipeline. As explained by Huang et al [17] the common problem with the EMD is frequent appearance of mode mixing, which is defined as either a single IMF consisting of widely disparate scales, or a signal residing in different IMF components. As a comparison, the result produced are also compared with the method proposed by Taghvaie et al [21] as they used the combination of wavelet and cepstrum.…”

“…In a pipe system with constant steady flow, the pressure rise for instantaneous closure is directly proportional to the fluid velocity at cut off and to the velocity of the predicted surge wave but is independent of the length of pipe [17]. The well known Joukowsky equation has been applied for sudden closures in frictionless pipes and given as: For an instantaneous closure, the head produced ∆H (m) by the surge is:…”