By sion932 
With the rapid development of high-voltage direct current (HVDC) transmission technology, especially the large-scale construction of ultra-high voltage (UHV) HVDC projects, the accuracy and reliability of DC voltage measurement devices have become crucial to the safe and stable operation of power systems. GB/T 26217-2019, titled DC Voltage Measuring Device for HVDC Transmission System, is a key national recommended standard in China that regulates the technical requirements, test methods, and structural design of DC voltage measuring devices for HVDC transmission systems. This article elaborates on the core content, technical characteristics, and industry significance of this standard.
1. General Information of the Standard
GB/T 26217-2019 was issued by the State Administration for Market Regulation and the Standardization Administration of the People’s Republic of China on December 10, 2019, and officially implemented on July 1, 2020. It replaces the previous version GB/T 26217-2010, adapting to the technical progress of HVDC transmission systems and the increasing demand for higher voltage levels. The standard is classified under China National Standard Classification (CCS) K41 (Transformers) and International Classification for Standards (ICS) 29.180 (Transformers, Reactors, Inductors), with a total word count of approximately 22,219 words.
The standard is proposed by the China Electrical Equipment Industrial Association and supervised by the National Technical Committee on High-Voltage Direct Current Transmission Equipment of Standardization Administration of China (SAC/TC 333). It was drafted by multiple well-known enterprises and research institutions in the power industry, including Xi’an XD Power System Co., Ltd., Xi’an High Voltage Apparatus Research Institute Co., Ltd., China Southern Power Grid Science Research Institute Co., Ltd., and Tsinghua University, ensuring its authority and practicality.
2. Scope and Core Technical Requirements
2.1 Application Scope
GB/T 26217-2019 applies to DC voltage measuring devices with a voltage level of ±1100 kV and below. These devices are typically installed in key positions of HVDC transmission systems, such as DC pole buses, midpoint buses of double twelve-pulse converter valve groups (if applicable), neutral buses, ground electrode leads, and bridge arm circuits of flexible HVDC transmission systems. The expansion of the voltage level from 800 kV (specified in the 2010 version) to 1100 kV aligns with the development of China’s UHV HVDC projects, such as the Changji-Guquan ±1100 kV UHV HVDC project.
2.2 Key Technical Provisions
The standard specifies detailed requirements for DC voltage measuring devices in terms of operating conditions, rated values, design and structure, tests, and nameplates.
In terms of operating conditions, the standard defines normal and special operating environments, including temperature, humidity, and altitude, to ensure the device can work stably under complex on-site conditions. For example, the temperature range for type tests is adjusted from -25 °C~75 °C (2010 version) to -40 °C~85 °C, enhancing the device’s adaptability to extreme climates.
Regarding rated values, the standard clarifies key parameters such as rated primary voltage (Udr), maximum continuous operating voltage (Udm), analog output rated value, digital output rated value, and insulation level. A new term “maximum continuous operating voltage” is added, and the digital output rated value corresponding to the rated primary DC voltage is modified from “2D41H” to “3A98H”, which is more in line with the technical characteristics of modern digital measurement devices. The insulation level requirements are also updated, with the maximum continuous operating voltage and corresponding withstand voltage values adjusted to match the ±1100 kV voltage level.
In design and structure, the standard puts forward requirements for general design, digital design, external insulation, anti-corrosion painting, electromagnetic compatibility (EMC), radio interference voltage (RIV), enclosure protection level, and maximum attenuation of optical fiber transmission. For instance, the static withstand load of primary circuit terminals is redefined, and the protection level of the enclosure is specified to ensure the device’s mechanical strength and environmental adaptability. The EMC and RIV requirements are crucial to preventing electromagnetic interference and ensuring the accuracy of measurement signals.
For tests, the standard classifies tests into type tests, routine tests, on-site tests, and special tests, and redefines the test items and criteria. The transient response and frequency response requirements, which were previously part of performance requirements, are incorporated into the type test criteria. The transient response test evaluates the response speed of the secondary voltage to the transient change of the primary voltage, while the frequency response test verifies the device’s measurement accuracy within a specified frequency range. Additionally, the accuracy class requirement specifies that the voltage error should be within the limit under specified operating conditions, with the voltage error calculated by the formula: ε = [(KU – U)/U] × 100%, where K is the rated voltage division ratio, U is the actual primary DC voltage, and U is the actual secondary DC voltage.
3. Main Changes from the 2010 Version
Compared with GB/T 26217-2010, GB/T 26217-2019 has undergone significant technical revisions to adapt to the development of HVDC technology and engineering needs. The main changes are as follows:
- Voltage level expansion: The applicable voltage level is increased from ±800 kV to ±1100 kV, covering the latest UHV HVDC projects.
- Terminology adjustment: Terms such as “step response”, “amplitude”, “phase”, “cut-off frequency”, and “IP code” are deleted; “rated DC voltage” is renamed “rated primary voltage”, and the new term “maximum continuous operating voltage” is added.
- Rated value optimization: The digital output rated value is updated, and the insulation level parameters are adjusted to match the ±1100 kV voltage level.
- Structural design revision: The static withstand load of primary circuit terminals is redefined, the temperature range for type tests is expanded, and the installation requirements chapter is deleted.
- Test system improvement: Type test and routine test items are redefined, and transient response and frequency response are incorporated into type test criteria, enhancing the comprehensiveness of performance verification.
4. Industry Significance and Application Value
GB/T 26217-2019 plays a vital role in promoting the standardization, upgrading, and high-quality development of China’s HVDC transmission industry. Firstly, it unifies the technical requirements and test methods for DC voltage measuring devices, solving the problem of uneven product performance among different manufacturers and standardizing the market order. This ensures the interchangeability and compatibility of devices, reducing the difficulty of project construction and operation and maintenance.
Secondly, the standard supports the safe and stable operation of UHV HVDC projects. As the core measurement equipment of HVDC systems, DC voltage measuring devices provide accurate data for system control, protection, and monitoring. The strict requirements of the standard on accuracy, stability, and environmental adaptability effectively improve the reliability of measurement signals, laying a solid foundation for the safe operation of power grids.
Furthermore, the standard promotes technological innovation and industrial upgrading. By incorporating the latest technical achievements and engineering experience, it guides manufacturers to optimize product design, improve production processes, and enhance the technical level and international competitiveness of domestic DC voltage measuring devices. It also provides a technical benchmark for the research and development of new measurement technologies, facilitating the development of smart grids and energy Internet.
GB/T 26217-2019 is a key standard adapting to the development of China’s UHV HVDC transmission technology. It comprehensively regulates DC voltage measuring devices from multiple aspects, including technical requirements, test methods, and structural design, and has significant guiding significance for the production, application, and supervision of related products. With the continuous advancement of HVDC transmission technology and the expansion of application scenarios, this standard will continue to play an important role in ensuring the safe, efficient, and stable operation of power systems, and contribute to the optimization of energy allocation and the development of a low-carbon economy in China.