Planned and proper validation of new technologies, including driving the correct inference from the validation test results, can help both the service provider and utility to avoid surprises and regrets at a later date. It is recommended to spend time and resources on validation rather than feeling helpless or frustrated later, advises Rajesh Bansal, CEO of BSES Rajdhani Power Limited.
The world over, the power distribution scenario is changing. The greater integration of renewable energy, growth in rooftop solar and need for electric vehicle charging are all leading to larger variation and unpredictability in the net power demand curve. With this, management is now the biggest concern and challenge for the utility.
Further, with the higher levels of engagement, meeting the expectations of consumers and other stakeholders is becoming another big challenge. With this changing scenario, utility objectives are also changing. To address these issues, concerns and expectations, utilities are opting for smart grid technology, with smart metering one of its key components (Figure 1).
Need for smart metering validation
Smart metering is one of the most desirable technologies for utilities and most of them are going for large scale implementation. It is important to note that smart metering is a tool, not a solution; and is also an integrated system, not a standalone product. The key question is how to ensure that the chosen ‘smart metering integrated system tool’ is effective and is the right one with the required capabilities to empower the utility to achieve its desired objectives. The only way, ahead of mass installation, is the process of ‘validation’.
A smart metering system is totally different from a standalone static energy meter. As an integrated system, the validation of a smart metering system is not merely the testing of the meter alone, but far more than that. Before going further, let us refer to some experiences encountered in the past:
- When an LV CT meter and the LV CT box were tested individually, they were accurate, but when coupled, the composite accuracy was out. In other words, the standalone and integrated behaviours can be different.
- When a ‘disconnect’ command was given, many meters did not disconnect. The reason was that the meter feeding power to the network went off first and affected the travel of the command to the remaining meters.
- At a particular location, a smart meter was found malfunctioning with intermittent functioning of load relay. The fault continued even after the meter was replaced and was later tracked to a powerful magnet in the speaker, impacting the performance.
- At a utility, many customers suddenly lost supply. This was tracked to a server having given a command to switch off but the ‘why’ and ‘how’ need investigation.
- A meter reader reported, ‘No display/ display not working’. When checked, the audit team found it working, indicating an intermittent behaviour.
- A smart fire sensor connected to the server was found less effective compared to a conventional sensor connected directly to the relay. Time is critical in protection with delays due to signal travel from sensor to server to the switchgear RTU.
From these incidents, we can conclude that validation of the product alone is not sufficient and needs testing far beyond the applicable standard or specification.
Meters and other components of a smart metering system can experience conditions not covered in the standard. While compliance with a standard can ensure a product works normally in defined conditions, the product should be checked in the conditions that may be experienced in the field. The validation engineer has to imagine the extreme scenario-based on field experience and plan the validation process accordingly.
The limit when a meter/system can malfunction or fail should be identified. This will help to understand the limitation of the system and to compare different product offers. The performance level, e.g. signal response time, can vary with the objective. Validation should be done keeping the objective in consideration.
Utilities are highly staked on their metering systems. Validation should be planned taking this aspect into consideration. An error in a bill can be a headline in the next day’s newspaper.
Finally, there are many parameters of meters, which the utility has no plan to use. A typical metering system life is 10 years and tests related to these parameters should be done. They may be needed at a later date. Cyber and data security are equally critical and should be part of the validation.
Validation is one of the most critical aspects to ensure the success of a smart metering project. It should cover all aspects of system. Any malfunctioning or undesirable behaviour in an integrated system or any lack of features, when found at a later date, may be too costly to rectify.
Role of smart apps
Smart phones are popular as they are frequently used and their popularity can be traced to the ‘smart apps’ which bring benefits to users. Similarly, in order to leverage the maximum benefit from a smart metering system, smart apps are needed to carry out the various functions (Figure 2). Thus, it is equally critical to validate the smart apps.
Planning smart metering system validation
For planning and preparation of the validation process, ask four questions:
- What should be validated? Validation is a process to ensure functioning of the system to meet the objectives without failure or malfunctioning in any field condition and to ensure the ‘return on investment’ and no regrets about the technology.
- How should validation be done? A series of steps are recommended, starting with understanding the objectives, both short term and long term, of the project:
- The first step is to define the process and strategy as to how the technology will be used to address the objectives. This mainly covers the data required and their frequency; logics for events, alerts, etc.; the processing, analysis and storage of data; and then inferring and planning actions.
- The probable conditions for when and what can go wrong should be identified and the system behaviour during extreme conditions checked.
- Who should do the validation? Validation should not be done entirely alone but in partnership with others such as vendors, independent test labs and other utilities. Their data can also be used to validate and certify the smart metering system. As the utility holds the biggest stake, the involvement of the utility engineer is a must in the entire validation process.
- What initial preparation is required? Three basic preparations are recommended:
- Manpower training – to understand the objectives, product, process and strategy.
- Test setup – in general not many instruments are required and rather than simulating field conditions in the lab, validation should be undertaken in real field conditions.
- Interpretation of validation results – to check compliance with the plan and understand behaviour under extreme conditions. These need to be analysed, reviewed and then inferences drawn. This also includes analysis and driving conclusions from similar tests done or actual field experience of other users.
Smart metering system validation is a specialised job and should be carried out before mass installation. The utility should have a dedicated team, which is well trained, and the required resources should be allocated.
For validation of the communication network, HES/DAS, computer system, data storage, MDMS, the services of field experts/vendors can be taken. However, the utility should be directly involved in validation of the smart meter and smart apps.
This description is just a skeleton structure on how to make validation roadmap, with guideline charts to prepare the validation process. Incidentally, there is no complete, structured roadmap is available. To prepare an effective validation process, basic knowledge about meters, the study of abnormal behaviour as observed by utilities and knowledge on how to use data to address objectives is a must.
Based on his past experience with static meters, data usage applications software and on the feedback and experiences of other utilities, the author is preparing a validation roadmap for the smart metering system, detailing a set of validation tests, test methodology and data collection chart and process.
About the author
Rajesh Bansal is an Electronic Engineering graduate, presently working as CEO at BSES Rajdhani Power Ltd, a power utility serving 2.7 million consumers in Delhi, India. He has 10 years’ experience in meter design and manufacture and 17 years’ experience in power distribution. His specialisation is in the field of meter management, meter data usage and network operations management.