This paper will focus on the utilization of advanced pipeline simulation software to proactively identify and rank distribution regulator stations based on their criticality to meet customer demand in an interconnected distribution system. A particularly complex distribution network modeled as a single system containing multiple subsystems operating at various pressure levels is analyzed over a large number of scenarios using PG&E's Batch Analysis Tool (BAT).
BAT has the capability to run numerous simulations in a time efficient manner to discover critical regulator stations within an interconnected distribution system in one hydraulic model. A fundamental issue with performing regulator station failure analysis is shutting in regulator stations can cause the system to "crash," that is, the model will not balance. If the model does not balance, it is not necessarily clear which portion of the system is affected based off of the software's error log. For example, if a model doesn't balance when an upstream regulator station is shut in, it may be difficult to conclude whether the upstream or the downstream subsystem is creating the hydraulic problem from the closure. With the help of BAT, system performance can be observed as temperatures decrease (demand increases) and the point at which the system crashes can be recorded. Furthermore, BAT can track the pressure at multiple locations to check at what point a certain area crashes.
Proactive gas system planning is to understand operating risks before they occur on the system. It is a goal of PG&E's Gas System Planning department to utilize hydraulic simulation to gain broad system intelligence over a range of conditions and to identify facilities that are the most critical to system operations.
Hydraulic simulation requires the usage/input of Heating Degree Day (HDD), Peak Hour Hactor (PHF) and a demands file containing customer usage loads. PG&E designs its gas hydraulic system to Abnormal Peak Day (APD) conditions, which is an extremely cold day that has been recorded once in a 90 year time frame. From a previous PG&E paper presented on the BAT, it was shown that BAT can automate the entire loading process of an individual simulation. This paper will look at the impact of BAT on critical distribution regulator stations.