Schneider Electric s Advanced Water Leakage Detection

Transcription

1 Schneider Electric s Advanced Water Leakage Detection February 2010 / White paper by Ivan Nazzaretto, Schneider Electric solutions manager - water utilities Make the most of your energy SM

2 Summary Executive summary... p 1 Introduction... p 2 Hunting down leaks yields multiple benefits... p 4 What is active leakage control?... p 5 SCADA used for leak detection... p 6 Schneider Electric software tools for leak detection... p 8 Savings with Schneider Electric s leak management solution... p 9 Conclusion... p 10

3 Executive summary There are several reasons why a water utility focuses on water loss control; it might aim for improved performance and service indicators; or compliance with regulatory requirements; or protecting a limited resource; or reducing the costs involved with treating and pumping lost water. In all cases, proactive searching for leaks helps identify new leaks as soon as possible, making the loss control process more efficient. Using a technique popular in oil pipeline management due of its effectiveness, the water utility can perform real-time analysis of hydraulic parameters, such as flow, pressure and level. Software tools using data available in the network supervisory control and data acquisition (SCADA) system can provide analysis for leak detection techniques, such as real-time mass or flow balance, pressure gradients, pressure transients, minimum night flow and trending. These analyses support timely and accurate asset management decisions. Schneider Electric s leak management solution includes the applications that perform network modelling and real-time analysis. This solution reduces the time required to detect a leak and identify its location, the time to repair and, as a result, the amount of water lost. This solution is applied worldwide to help sustain and secure the availability of the world s most valued resource. Water leak detection can help reduce a multitude of issues White paper on Water Leak Detection 01

4 Introduction Water loss is a major concern for most water utilities worldwide, as it affects not only operational processes, but also impacts the financial, social, and environmental aspects of the utility. A 2006 report published by the World Bank declares that the total cost of non-revenue water (NRW) for water utilities worldwide can be conservatively estimated at $14 billion per year, with twothirds of it occurring in the developed countries. 1 Water losses can be classified as real (physical losses) or apparent (economic or commercial losses). Real water losses reflect water lost from the network and not used; these losses result from leaks in the distribution system, overflows from reservoirs, washouts, etc. Apparent water losses reflect water that is actually consumed by users, but unmetered or not correctly metered, and consequently unaccounted for. Here, we refer primarily to real water losses, focusing on the detection of leaks (or leakages) in transmission and distribution mains where most network water is physically lost. In this paper, we discuss how Schneider Electric s leak management solution integrates with the enterprise SCADA system and uses the system s real-time data to promptly identify the presence of leaks or bursts and minimize costs and other adverse impacts for the utility. 1 White paper on Water Leak Detection 02

5 Non-revenue water can cost utilities a collective $14 billion per year

6 Hunting down leaks yields multiple benefits Traditionally, water loss control activities are carried out to minimize the impact of inefficient processes and to support operations stressed by water supply limits. While intermittent supply and process disruptions are still primary instigators for leak detection activities, even well managed utilities and those operating with ample supply of fresh water have reasons to go after water loss. Shareholders continuously seek financial optimization. The reduction of NRW can result in an increase of revenues if the water demand is not entirely satisfied. Further, it reduces the expense of treating and pumping lost water. Finally, leak detection and repair often is a less costly alternative to tapping new water sources. Consider, too, the increasing impact of stakeholders on utilities water loss control policies: Government, via legislation, economic and environmental regulators, setting increasingly stringent leakage guidelines and targets All of these concerns can have a direct or indirect impact on the utilities: at best, they impact corporate image; at worst, they are the basis for imposed penalties, tariff caps, and service contract breaches. Whether a serious operational or financial concern or a matter of reputation, leakage is an issue that simply cannot be ignored. Customers, becoming more cognizant of water usage and leakage White paper on Water Leak Detection 04

7 What is active leakage control? It is commonly accepted that a sustainable strategy to control real water loss must embrace four main tactics: Active Leakage Control (ALC) Pipeline and asset management Speed and quality of repairs Pressure management Active Leakage Control can be defined as the policy of proactively searching for hidden leaks. In its most basic form, ALC consists of periodically sweeping the water network using one or more techniques to identify the presence of leaks in water mains. A more comprehensive approach to ALC is to make network flow measurements on a regular basis to identify new leaks as soon as possible. It is evident that the sooner a leak is detected, the sooner field survey activity can begin to locate and repair the leak. Detecting leaks quickly after they form requires real-time or near-real-time analysis of hydraulic parameters (flow, pressure, and level) throughout the water distribution system. White paper on Water Leak Detection 05

8 SCADA used for leak detection The SCADA system is an ideal platform for performing advanced analysis to promptly identify the presence of a leak. Nevertheless, many water utilities still do not exploit their SCADA system to its full capability in controlling leakage, often limiting the SCADA to collecting periodic flow data to calculate water balances and estimate water loss. In contrast, the oil industry makes extensive use of software tools, when installed on top of the SCADA system, proactively execute leak detection. Leak detection techniques based on SCADA system analysis Leak detection systems based on the data collected from field instruments typically apply one of these leak detection techniques: Balancing of pipeline input versus output: this leak detection technique relies on the simple fact that fluid mass flowing into the pipeline equals the flow out in a leak-free pipeline. A difference between the input and the output suggests the presence of a leak. Hydraulic analysis: measured values of flows and pressures are compared with simulated values of the same variables, calculated by verified hydraulic models. Significant discrepancies might signal the presence of leaks. Monitoring signals generated by a leak: a burst will cause a sudden pressure drop that will create a pressure wave travelling at sonic velocity, both upstream and downstream from the leak. The leak location can be calculated using the time difference in detection by the nearest sensors on either side of the leak. Hydraulic parameters trending analysis: flow (especially minimum night flow) and/or pressure trends can indicate a leak. Typically an increase in the flow and a decrease in the pressure, compared to average conditions, suggest new leaks have appeared. White paper on Water Leak Detection 06

9 SCADA used for leak detection, continued Methods supporting techniques 1, 2, and 3, below, are used primarily to detect and locate bursts in water transmission schemes where metering accuracy is usually high, operations are quite steady, and the presence of nonmetered customers is negligible. However, the negative pressure wave technique presents some inconveniences: it only detects the initiation of a leak and not its presence after it has established. Further, false alarms can be triggered by pressure transients generated by noise-producing installations such as pumps. distribution networks, preferably at a districtmetered-area (DMA) level, integrating data from the DMA inlet meter with the SCADA system. In a typical water supply system, real losses might exist in the distribution networks and in transmission schemes. Therefore, it might be necessary to deploy more than one of the mentioned leak detection techniques in order to achieve comprehensive leak detection. Methods associated with technique 4 are typically applied to determine the presence of leaks within Leak Detection Methods Leak detection technique Method used 1 Balancing of pipeline mass input vs. output Mass balance Flow balance 2 Hydraulic analysis Divergences between measured and calculated flow/pressure valves Pressure gradients analysis 3 Monitoring of signals generated by a leak Pressure transients analysis 4 Trending analysis Minimum night flow analysis Flow/pressure trends analysis White paper on Water Leak Detection 07

10 Schneider Electric software tools for leak detection All the methods described above require analysis of data collected by the SCADA system so that they are available to support informed decisions. Analysis can be simple, such as comparing a single element (i.e., flow or pressure in a single point of the water network) to a threshold limit. Or, analysis might be extensive, involving multiple elements with dynamic thresholds. Without specific software calculations, comparisons with historic data and exchange of information with other enterprise systems would be extremely difficult if not impossible to carry out in a timely manner. With extensive experience and expertise as a SCADA vendor and water loss management consultant, Schneider Electric has developed several applications to perform real-time network analysis and modelling for leakage detection. These applications are packaged as the leak management module of the Schneider Electric Water Management Suite solution. These applications work within a single framework to analyse real-time data from SCADA systems, and allow the water operator to assess the presence of leaks in different areas of the network through: Real-time mass balance calculations Real-time flow balance calculations Adaptable alarm management based on current network operations Minimum night flow periodic calculations Automatic cross-check of real-time measured data vs. hydraulic simulated data These advanced tools are inter-related, adaptable to customer network conditions, easily configurable, and scalable to support operations ranging from simple transmission schemes to complex water distribution networks. White paper on Water Leak Detection 08

11 Savings with Schneider Electric s leak management solution The total lifetime of an active leak can be divided into three distinct phases (see Figure 1): Awareness the time between when a leak first occurs, until the time the utility is aware of its presence Location the time it takes to investigate and pinpoint the location of the leak Repair the time it takes to carry out the repair once the leak location has been specified Burst flow rate Awareness Location Repair Time Figure 1 Schneider Electric s leak management solution reduces the time required to detect the leak the awareness time. After detection, hydraulic analysis tools help investigate and identify with reasonable precision the location of the leak. Burst flow rate Awareness A Location A Repair Time Burst flow rate Awareness Location Repair Water saved with WMS Time White paper on Water Leak Detection 09

12 Conclusion Water leak management in a nutshell: The Schneider Electric leak management solution helps ensure efficient ACL by immediately detecting a new leak occurrence through real-time data collection and analysis. Reports and alarms are issued immediately to the control room. This system allows the user to choose from five leak detection methods, enabling the solution most appropriate for the specific distribution network conditions. White paper on Water Leak Detection 10