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.
This paper will present actual use cases of batch analysis technology using PG&E’s Batch Analysis Tool (BAT) on gas distribution systems. This paper supplements the PG&E paper Pipeline Simulation Modeling Advancements – Numerous Scenarios Analyzed Simultaneously.
PG&E Distribution and Transmission Planning Engineers use the BAT for a variety of functions. This paper will examine the details of specific distribution focused use cases and consider future applications for the BAT. The use cases that will be examined include:
System intelligence, operational optimization, and efficiency of analyses will be demonstrated.
Overview of the Distribution Batch Analysis Tool
As discussed in PSIG paper 1613 Pipeline Simulation Modeling Advancements – Numerous Scenarios Analyzed Simultaneously, the volume of hydraulic simulations performed by Gas System Planning has dramatically increased due to an unprecedented increase in the amount of reliability work across PG&E’s service territory. This has resulted in a substantial workload increase for Planning Engineers. In order to keep pace with this increased workload and provide complete and comprehensive hydraulic analyses, PG&E’s Gas System Planning has developed a Batch Analysis Tool (BAT). This is an Excel® based tool that allows for user defined batch simulations of hydraulic models. This tool enables Planning Engineers to set up a series of simulations to be performed in an automated, sequential order rather than manually performing each simulation one at a time. This allows Gas System Planning to devote more time to evaluating hydraulic analysis results and gaining system intelligence, rather than performing simulations manually.
When conducting a hydraulic analysis, multiple input parameters influence a system’s performance. For example, during a system outage analysis, the system will perform differently depending on various factors including the specified ambient temperature, the system’s operating pressure, valving operations, etc. If every possible combination of these parameters were to be examined, the total number of simulations would increase geometrically. Performing an analysis of this magnitude manually would require a significant amount of time. The BAT allows the Planning Engineer to examine and vary each of these parameters, creating simulations ranging from 10 runs to thousands of runs, if desired. Performing such detailed analysis is both comprehensive and time efficient.