In order to meet the application needs for electrical energy metering, customer service management, trade settlement, power supply contracts, tariffs and so on, several standards have been developed and are in force in China. These application needs cover all the commercial business processes of the utility, starting with metering and ending with billing, and include system integration, demand for energy metering management and power generation, transportation and distribution in China’s power market.
These standards apply to multi-function Watt hour meters; data exchange for electricity metering (Companion Specification for Energy Metering, COSEM); and reliability standards for mechanical and static electricity meters.
MULTI-FUNCTION WATT HOUR METER
The standard currently in use for multi-function electricity meters is DL/T614 Multi-function Watt hour Meter, which was published in 1997. It relates mainly to electromechanical meters, and does not include specifications for electronic multi-function electricity meters. Specifications are not yet available for multi-function electricity meters in the IEC standard systems, as different functionality is required in different countries.
However, countries where the reform of the electric power market began comparatively earlier all have their own corresponding standards and specifications. Examples are Germany’s PTB-A 50.7 Anforderungen an elektronische und software-gesteuerte Messgeräte und Zusatzeinrichtungen für Elektrizität, Gas, Wasser und Wärme; Britain’s Code of practice five; and Australia’s national standard AS1284.12-1995 Electricity metering Part 12: Poly phase multifunction (non-demand) watt hour meters (class 1).
In China, the Particular Requirements for Multi-function Electricity Meters is now being drafted by the National Committee of Standardisation Techniques for Electrical Measuring Instruments. The standard specifies particular requirements for multi-function electricity meters which can measure and display more than one type of power, such as active and reactive power, while being integrated with some additional functions.
The features of China’s power market deregulation, the demands for metering management and power generation and distribution in China’s market, as well as the use of multi-function electricity meters in China, are all taken into account during the formulation of standards. The standard is expected to clearly define the requirements for multi-function electricity meters in the following aspects: basic and additional functions, display, security, event log and software requirements, and to standardise the display format and the auxiliary connection terminal.
DATA EXCHANGE FOR ELECTRICITY METERING
More and more commercial firms are using intelligent meters in their metering and billing systems. Previously, the commercial value of meters was based on their data acquisition and processing abilities. Now the value depends on their interoperability and system integration. Therefore IEC TC13 published the IEC 62056 series of standards: Electricity metering - Data exchange for meter reading, tariff and load control. The COSEM (Companion Specification for Energy Metering) is a set of international standards which consist of six parts.
The release of these technical specifications enables all relevant meters, support tools and other system devices to be interoperable and easily integrated. The National Committee of the Standardisation Techniques for Electrical Measuring Instruments (TC104) is arranging for experts to translate these standards into Chinese and to prepare them for transfer to China’s national standards.
RELIABILITY STANDARDS FOR MECHANICAL AND STATIC ELECTRICITY METERS
Since 1998, China has invested a great deal of money in constructing and rebuilding power grids in cities and rural areas, and to implement a ‘one house, one meter’ policy for urban and suburban residents. Demand for residential single-phase electricity meters has thus dramatically increased. The number of installed single-phase electricity meters in China is over 30 billion units – the largest in the world.
However, China lags far behind industry-leading countries such as Switzerland, England, Germany and the United States in both meter reliability and sampling survey standards of the electricity meters in service. At present, electricity meters in the countries mentioned must periodically be sampled for certification to detect errors and determine the replacement period. In China, electricity meters are still being replaced on a fixed cycle.
In a deregulated environment, the fixed cycle method of meter replacement hampers technological progress. The IEC has published two reports in recent years: Dependability – Part 11: General concepts and TR62059-21 Dependability – Part 21: Collection of meter dependability data from the field. The reports include the basic concept of reliability and the acquisition and analysis of on-site failure data of static electricity meters. In addition another three standards, related to accelerated testing for reliability, reliability prediction and software reliability, are in progress.
Until now, China has only had one mechanical meter industry standard: JB/T50070-2002 ‘Reliability Requirements And Compliance Test for Electricity Meters’. This standard specified methods for testing electricity meters in a laboratory environment, to ascertain whether they met reliability requirements as laid out in the product contract and product specification. There are different failure modes for mechanical meters and static electricity meters. Countries like Switzerland and England have accumulated rich experience of on-site mechanical electricity meter sampling, and much progress in this area has been made in recent years.
Several Chinese manufacturers have now designed and produced long-life (up to 25 years) electricity meters. If the old certification technologies continue to be used, it could prevent wide-scale application of these advanced technology meters. To solve problems of regular (short-term) replacement of numbers of residential electricity meters, a working group is drafting the Verification Regulations of Residential Single-phase Electricity Meters.
This document sets out the sampling solutions and sampling result determination for electricity meters in the field. On the basis of extensive research and participation from industry players, the draft of the regulation has been completed and submitted to the National Metrology Technical Committee on Electromagnetic Meters for approval.