Meeting demands for long term HV grid metering precision


As deregulation accelerates and energy is increasingly bought and sold between countries, HV grid operations are becoming more complex, owing to the increasing number of billing points between the different participants in the expanding global electricity market. These players include power generation companies, independent power producers, grid operators, distribution companies, international or regional intertie points and major industrial customers. As a result, increasing numbers of very large bills generated by electricity meters are being exchanged every month.

HV grid metering operators have a major responsibility in this high value billing process and it is essential that they deliver completely reliable data to the market operators. To ensure this, very accurate metering data and 0.2% accuracy class as the basic standard are a fundamental requirement, although the current tendency is to exceed this standard, with better than 0.1% accuracy within the whole operating range, including frequency and temperature variations.

In addition, there are other specific requirements, such as extremely low energy resolution and infallible time keeping for spot pricing. Very high precision also helps significantly with minimising HV grid losses, and various technologies are already available that meet the basic criteria for high accuracy. Stability and long-term accuracy, with low maintenance needs, are just as vital for sound operations. Since major financial investment is required to support current network and HV grid development, guaranteed lifelong meter stability is essential in order to depreciate the investment over as long a period as possible, without significant additional maintenance costs.

While all meters need to preserve their accuracy for years, this is even more critical for an HV grid meter, as disputes arising from inaccurate metering data have a very high financial impact on HV grid operations. An error of only 0.1% dramatically affects a multi-million dollar invoice! Over and above the financial aspects, HV grid metering operators are expected to serve as “trustees” for the grid participants, to prevent the number of disputes, valid or invalid, increasing as these market participants multiply.

Once an HV grid meter is correctly commissioned, the metering operator must be able to have confidence that its data will remain reliable over time.

ACE8000 PowerGrid combines high acuracy and lifelong reliability

To respond to these needs, Actaris sought to produce a high precision meter with 0.1% metrology that could offer power generation plants, utilities, grid owners and other large customers a high precision metrological engine and longterm stability.

Combined with a technically advanced meter reading system (such as Actaris’ ACE Vision), this solution would offer a comprehensive meter management system and portfolio. Actaris development teams aimed to achieve a meter with the necessary high precision and long-term stability by designing a robust front-end built of passive-only components, directly associated with a fast and accurate A/D converter. The current sensor is a passive current transformer with a core made of new, ultra-thin nano-crystalline material to provide excellent linearity within extended current frequency and temperature ranges, and proven long-term stability.

Other components in the front-end metrology include high grade resistors with a very low specific temperature coefficient. This meter’s performance remains consistent over time, securing revenue within 0.1% accuracy over the entire life of the product.

Advanced resolution for high-end applications

The new meter, the ACE8000 PowerGrid, is driven by a powerful microprocessor with 1 mWh energy resolution. This allows recording of large power variations without incurring financial losses and, coupled with a very high stability time clock, provides the highest integrity in billing, which should help to reduce potential disputes caused by a lower resolution and accuracy. With four megabytes of mass data storage in Flash memory, the meter allows multiple recording of load profiles, up to sixteen independent channels in absolute or incremental format, and a comprehensive list of network monitoring events.

It supports multiple communication channels and can communicate on independent ports over several open and standard protocols such as DLMS COSEM over TCP/IP for remote reading and billing or for SCADA systems. Actaris ACE8000 PowerGrid is designed with maximum flexibility in communications techniques that are likely to evolve within its long lifetime.