Meter and billing auditing of commercial and industrial electricity customers in a Metro Municipal Electricity Utility

Transcription

1 Meter and billing auditing of commercial and industrial electricity customers in a Metro Municipal Electricity Utility SARPA Conference: July 2010, Johannesburg By: Kobus van den Berg (Pr Eng) Principal Engineer, NETGroup

2 1. Introduction Revenue protection processes are normally designed to reduce possible loss of revenue to a utility due to technical and more frequently non-technical losses. The aim will normally be to ensure that technical standards are adhered to and that quality control processes are in place to ensure that the systems are functioning reliably and correctly. There are however many loopholes in the processes and in numerous cases these anomalies and errors slip through and result in major losses to either the customer or the utility. In the case of large power users a small error in for example the meter or billing processes could result in major cost implications. This paper will attempt to highlight some of these problem areas actually experienced in the field during a process to clean up errors and thus a loss of revenue to the utility in the commercial and industrial sectors. The approach is not the conventional blanket meter auditing or screening process but rather a procedural and data mining analysis. The paper will also highlight the necessity to combine technical, financial and operational processes and skills. In this process a silent killer from within was discovered as skills decline, automation increase and the sense of ownership disappears. Our utilities are not very aware of the specific problems, and thus loss in revenue, facing them due to the fact that in many cases the different sections and departments work in silos. One often finds that the financial officials do not understand the tariff and technical issues whilst the technical staff is only concerned with the metering installation and ignores the financial implication of what they are doing. Customers find it very difficult to obtain information (experienced in more than one electricity utility) from the various sections and it makes it virtually impossible to trace problems ranging from metering, reading and eventually billing problems. Customers are merely ignored in the process and more than often are literally left in the dark. 2. Bulk meter AMR (Automated Meter Reading) system the solution to all your problems? So you have convinced management that manual meter readings are unreliable, the utility is losing a lot of revenue and the latest automated meter reading equipment will solve all your metering and billing problems and thus result in timeous, 100% correct bills to all customers? All readings are electronically collected and transferred to the billing system with very little human intervention and thus less chance for errors to creep in. Customers can now track their meter readings and consumption on a website and pay their bills with a smile. RIGHT??? WRONG!!!!! 3. Problem Statement The following problems have been identified and in the rest of the paper a brief description will be given as to how the challenge was approached. a. AMR electronic metering systems are not infallible

3 b. Data bases are not reliable due to inconsistent/ incorrect data capturing processes c. Billing systems bill what ever readings are submitted d. Electricity tariffs are not applied correctly. e. Meters are not installed and maintained effectively f. Metering processes allow incorrect installations and failures to exist for quite some time before faults are corrected g. Not withstanding all the NRS standards and code of practices ( NRS 047, 049, 057, 055, 071 etc), a host of IEC and SANS specifications and NERSA distribution license requirements errors still occur on a larger than expected scale. h. Very few overall quality management processes are used i. Metering and billing errors are costing utilities dearly in the bulk supply sector j. Customers are at the mercy of utilities as far as correct billing and metering is concerned and it is a major project to convince a utility to talk to the customer and assist with corrections. The end result is major cost implications to either the customer or the utility. 4. Correction strategy a. Identify the sources of possible revenue collection losses b. Design monitoring triggers to flag a problem when it occurs c. Use appropriate analysis methodologies to identify and correct problem d. Use appropriated reading/ data correction methods e. Establish customer liaison process f. Establish bill correction process. g. Ensure that effective quality control is used when meter is installed. h. Ensure that all processes from the application to the monthly billing are effectively linked and data integrity maintained. i. Communicate with the customer to obtain his inputs and consent j. Ensure that a comprehensive over-all meter management process is in place k. Integrate technical, tariff and financial skills in the management team to ensure that the total problem is analyzed and corrected. 5. Errors encountered in meter reading and billing processes. The following errors were encountered during the project and serves as a representative but not exhaustive list of problems occurring in bulk customer metering and billing systems: a. Incorrect billing readings due to metering or reading errors. b. Gaps (not all 1/2h data received) in data and bills caused by data collection and billing problems c. Meter time change spikes due to technical processes can cost the customer a significant amount if it affects the demand or NAC readings. d. Communication errors form a major part of the problems encountered. The communication system (mainly GPRS) and modems are simply not reliable enough to ensure that data will be available when required.

4 Communication network failures as well as modem failures are common issues to address continuously. e. Tariffs incorrect due to the fact that tariff determination and the implementation of tariffs on the AMR and billing systems lack a procedural and reliable process. Some staff members who are responsible for tariff implementation simply do not understand more complex tariff structures and the interaction between tariff components. f. Meter installation incorrect due to technical and installation data capturing. These problems include incorrect CT/ VT installation as well as ratio implementation. The electronic metering systems do not all operate in the same way and where a large number of different makes and model of meters are used one often finds that the setups and ratio data are different causing confusion when the systems are implemented. The system should rather be standardized on only two or three systems making maintenance and operation significantly less complicated. g. VT/CT failures. These problems can normally be identified effectively if the AMR system also reads the meter events as well as phasor diagram information and instantaneous voltage and current readings during normal customer operational times. Many AMR systems only read profile data that makes remote monitoring of the meter system very difficult. It is absolutely essential that this information be retrieved from the metering system for management purposes. h. Billing components incorrect (units corrected but not MD and NAC) 6. Monitoring triggers To ensure that problem areas are detected timeously and the corrective action taken, a monitoring system with trigger points to identify and raise the problem with the correct team should be implemented: a. Customer complaints should be logged and referred to the appropriate section (technical, finance, management etc) with effective feedback mechanisms. b. Bill transaction trend anomalies can be used to visualize possible problem areas. Fig 1 shows a typical transaction trend indicating the inconsistencies. This method serves as a trigger for additional investigations due to the fact that the problem could be anywhere in the reading/ billing chain. c. Reading trend anomalies can be identified by screening AMR and manual readings before it is submitted for the billing cycles. The billing readings can be affected by technical, communication, tariff change, meter fault, readings and database errors. These deviations can be sudden changes in demand or energy consumption. These trend deviations can often be linked to a technical failure, meter change or tariff change. If the tariff is for example changed from a standard unit plus demand tariff to a Time of Use (TOU) tariff the appropriate readings for Off Peak and Peak units should also be transferred to the billing system. It could also involve the establishment of additional tariff components like network access charges. Fig 2 and 4 in the

5 annexure shows typical examples of demand and unit trend reading problems. d. Profile disturbances can normally be visualized on the profile graph. The profile graph provides an excellent screening tool to visually see possible error conditions to trigger further investigation. In Fig 6,7,8 meter failures can be seen (communication, VT, CT or meter itself). Fig 9 and 10 show a disturbance affecting two ½ readings increasing the demand significantly and thus also the Network Access Charge for the next 12 months (the additional demand alone would cost this customer R54k). The problem was apparently caused by a meter time set operation. Without detailed AMR profile and meter event recording it would have been impossible to spot this problem. e. Missing 1/2h data, gaps in data should be reported by the AMR system. To distinguish between missing data and a power failure is normally difficult but the meter events recording will give an indication of a power failure and restore event. Data could be lost in the communication or database storage process and the meter would then not be aware of the problem. A gap in data as shown in figure 7 could be costly loss revenue to the utility (this particular case amounted to R483k in the case of a major customer) f. The power factor can also be used as a filter mechanism to indicate possible problem at a metering installation. The power factor could indicate a CT/ VT problem or a genuine problem on the customer s side in terms of the actual load. The customer could use power factor correction equipment to rectify the situation. The average power factor could be calculated from ½ readings but an instantaneous reading could be valuable if taken during operational times and not during the night when the load is very low. g. By monitoring the customer s load factor one can identify changes in consumption. Low load factor could be an indicator of a meter reading problem. h. An incorrect phasor diagram should be a giveaway that a problem exists. Problems in the installation like, VT/ CT failure or an initial faulty installation can be identified. Be however sure that the variables for the phasor diagram has been read during normal operation times and conditions. A low load on a transformer can lead to confusing phasor diagrams. Fig 11, 12, 13 and 14 are typical examples of actual problems encountered. i. When a meter is changed due to failure, tariff change or upgrading one should check the installation from a quality control point of view. What is however also important is that the readings from the old meter and the new meter are synchronized on the billing to ensure that all energy is billed, the demand is only billed once during a month and that no units are lost during the transition period. This problem has been encountered in numerous cases where readings do no fit into the normal demand and unit trends and should be adjusted. j. Tariff changes provide an excellent opportunity to get the billing wrong during the first month at least. A mid-month transition or meter change makes it difficult for officials, meter reading systems and

6 billing to ensure that the customer are billed fairly, especially with more complicated tariff systems like TOU systems. k. Peer group comparisons can also be used as a tool to verify that a certain type of business is using a realistic amount of power and the demand is acceptable for the type of installation. In an actual case a big hotel was billed for a demand 30kVA (see fig 8). In this case it was obvious that something serious was wrong. The metering system was correct but a mistake was made in the calculations of factors in the AMR system. 7. Reading correction methods and process Legislation, standards and code of practices in South Africa is fairly silent on corrective processes and algorithms. At best it recommends that it should be based on historic data and a method agreed upon by the customer and utility. The legislation and codes of practices are discussed in the next section. In typical municipal bylaws historical data of three months before, three months after the problem period as well as the same period in the previous year is recommended. Although this is a solution it does not cover all situations nor is it always fair towards the utility or the customer. The following methods were used under different situations. To ensure that the process is successful a few rules (constitution of meter reading correction) have been defined namely: a. Rule number one : Be fair in the process b. Rule number two : Involve the customer and the utility in the process c. Rule number three: If a customer wants to involve an external consultant allow this and discuss the issues with this person. d. Rule number four: Compile a detailed report (technical as well as financial) to ensure that every body understands the issues and it can be used to explain to municipal technical, financial managers and especially auditors what the issues were at the time of correction. The information used for the corrections were obtained from the following sources: e. Historic data from billing system (bills, readings, journals) f. Historic data from AMR system ( ½ hour readings, profiles, monthly bills, meter data, phasor diagrams) g. Meter commissioning sheets. (meter installation parameters) h. Feedback from Metering section (historic and maintenance problems) i. Feedback from AMR operator ( installation, calculation, data, errors) j. Feedback from financial sections ( billing and customer information) k. Meter reading management database (monthly readings uploads, account information, meter information, location information, GIS information) l. Data from fault logging system ( faults, history, correction progress) m. Information from customer (the customers consumption, internal metering system data if available, operational processes, tariff options)

7 Correction techniques used n. Averages of long term consumption as well as three month consumption data as prescribed in bylaws. o. Averages over a few years for example for December months when consumption is different from the period before an after. p. Raw data to correct short term gaps and recalculation of trends and hourly consumption. With raw data days of the week can be replaced with corresponding ½ readings of the previous or following day. q. Regression methods to determine trending information r. Excel trending facility (example 3 month trend) super-imposed on actual readings to ensure that corrected data fit into trending curve. s. Where VTs or CTs failed it is often possible to correct the faulty existing data with a multiplication factor depending on what failed. t. Graphing the before and after correction values (refer to figs 3 and 5 in the annexure) will normally generate a good visual inspection model for the corrected values. This method also explains what has been done very effectively and can easily be explained to all stakeholders. u. After the reading reconstruction has been completed the recalculation of the bills will provide the cost implication that can also be trend graphed to again verify the integrity of the correction. v. Compile a detailed report to explain the interaction between technical financial and customer related issues. 8. Codes of practices regarding correction methods The existing documentation in South African distribution industry namely legislation, municipal bylaws, distribution grid code as well as NRS code of practices have been scanned for a standardized procedure to correct faulty meter readings. Most of these documents are very vague and merely states that correction should be based on agreed methods using historic data. a. Electricity Regulation Act 4 of 2006 The Act is silent on readings and correction methods b. Municipal Bylaws; Typical Bylaws on meter data correction: (1) When the Council is satisfied that a meter has ceased to register correctly the reading shown thereby shall be disregarded and the consumer:- (a) Shall be charged in respect of the current meter reading period the same amount as he paid in respect of the corresponding period in the preceding year, subject to adjustment necessitated by an alteration to the electrical installation of the tariff; or (b) if he was not in occupation of the premises during the corresponding period referred to in 11(1)(a) he shall be charged on the basis of his consumption during the 3 months preceding the date on which the meter was found to be registering incorrectly; or (c) if he was not in occupation of the premises during the whole of the period referred to in 11(1)(b) he shall be charged on the basis of his consumption during the 3 months following the date from which the meter was again registering correctly.

8 (2) If it can be established that the meter had been registering incorrectly for a longer period than the meter reading period referred to in 11(1)(a), the consumer may similarly be charged for the corresponding meter reading periods, provided that no amount shall be so charged with respect to a period in excess of 36 months prior to the date on which the meter was found to be registering incorrectly. c. NRS 057 (Code of Practice for Metering) merely states the following: Data estimation Data estimation will be required where actual meter readings are not available. NRS specifies the requirements for estimating meter readings. Raw meter data integrity In correcting any working data, the raw meter data shall be protected from being changed. In cases where raw meter data needs to be changed, it shall be archived As far as data integrity is concerned NRS 057 states the following. The utility should thus ensure that the AMR system complies with these requirements Data checks: All raw meter data shall be checked for validity at regular intervals or at a frequency that will allow a further interrogation of the meter (or both) before the data is overwritten within the meter and before this data can be used for any purpose. Validity checks shall include the following, as a minimum: a) checks for missing data; b) checks for invalid dates and times; c) checks of zero consumption levels; d) comparisons with standard or previous consumption patterns; e) checks of the sum of demand values against the register advance; and f) investigations of any meter error codes. d. NRS 047 (Code of Practice for Quality of Service) states the following : Estimated energy consumption In cases where it is necessary to estimate electricity consumption for a particular period, the method of estimation shall be based on historical data or, in the absence of such data, on a method agreed upon between the customer and the licensee. e. NRS 055 (Code of practice for Revenue Protection) is currently silent on data correction methods f. NRS 071 (AMR systems) states the following The master station software shall make provision for the estimation of corrupt data only. The software shall be able to distinguish between corrupt data and data recorded during power interruptions. Estimation algorithms shall be submitted to the users or potential users of the software for scrutiny and acceptance

9 The consumer may similarly be charged for the corresponding meter reading periods, provided that no amount shall be so charged with respect to a period in excess of 36 months prior to the date on which the meter was found to be registering incorrectly. 9. Summary a. Technology can be of great assistance but good management practices are required to ensure that utility meter reading and billing processes are successful b. The loss of skills is costing utilities and customer a massive amount of money and utilities will have to embark on processes to ensure that metering and billing is performed correctly. The integration of technical, financial and customer skills is essential to address the problem effectively. c. Appoint a dedicated team (internal or contractual) to supervise and manage all metering related activities. d. Even if AMR system are used with electronic bulk meters the supporting quality and supporting processes are essential e. Set up trigger mechanisms to identify and report any failure in the metering and billing system f. Correct the incorrect readings and bills as swiftly as possible g. Involve the customer throughout the process h. Be fair towards he customer and utility. i. Ensure that the AMR system used, collect all relevant meter reading and technical information from meters to assist with meter management

10 Annexure: Fig 1: Transaction trend: Fig2: Demand trend Fig3: Corrected Demand Trend Fig4: Unit trend

11 Fig 5: Corrected Unit Trend Fig6: Profile VT failure (before and after correction) Fig 7: Profile gap causing a loss in units Fig 8: Incorrect VT/CT ratios causing a major hotel to register MD of 30kVA

12 Fig 9: Spike on normal MD trend Fig 10 : Spike clearly shows an abnormal event Fig 11 3Phase 3wire Phasor diagram with a problem

13 Fig 12: 3 Phase 3wire phasor diagram with current and voltage nearly 90 out of phase Fig 13: 3 Phase 4wire system with incorrect CT connections. Fig14: 3phase 3wire system with Blue phase VT failure