Playing the "trilogy" of technical support for high-altitude UHV DC power grid phase shifter

China Energy Storage Network News: Qinghai has a vast territory and a special geographical location. It is rich in water energy, solar energy, wind energy, geothermal energy and other resources. It is an important renewable energy base in China with huge development potential.

"Red, orange, yellow, green, blue, and purple, who is dancing in the sky with colorful streamers?" With the efficient implementation of the national energy revolution and energy development plan, the hydropower stations competing on the plateau rumble on the green rivers, the rows of wind turbines operate vigorously, the photovoltaic ocean shines brightly, and the powerful electricity is continuously transmitted to the distance along the ultra-high voltage power grid. Everywhere, there is a grand scene of the people of the plateau working hard on green energy construction...

In accordance with the requirements put forward by General Secretary Xi Jinping during his inspection of Qinghai to build Qinghai into a highland of clean energy industry, a vigorous energy revolution and a grand project of new energy planning and construction are booming. In recent years, Qinghai Province has actively responded to the national energy planning and development strategy, guided the rational layout of power sources, and orderly promoted the large-scale development of new energy such as solar energy and wind power in the province. The construction and development of new energy in Qinghai power grid has made rapid progress, and the proportion of installed capacity has increased significantly. Affected by the characteristics of new energy power generation, the hydropower and thermal power that perform frequency regulation and peak regulation tasks in Qinghai are limited in installed capacity, and the voltage support capacity cannot meet the requirements of large-capacity, ultra-high voltage, and long-distance transmission of new energy with a high proportion, which seriously troubles the safe and stable operation of the power grid and the new energy absorption capacity. Synchronous phase regulators have excellent transient and steady-state characteristics and reactive power regulation capabilities, which play an important role in maintaining the voltage stability of the power system; at the same time, they can improve the system short-circuit capacity and short-circuit ratio, strongly support the large-scale transmission of new energy, and provide support for the safe and stable operation of the large power grid. Qinghai Electric Power Company has successively built two head-end converter stations in two 10 million kilowatt bases in the province (Haixi and Hainan), equipped with 6 300Mvar large-scale synchronous phase regulators. It has also put into use 21 distributed phase regulators in Hainan Prefecture this year. In the future, a large number of centralized and distributed phase regulators will be planned and built and put into grid operation.

In order to further enhance the security and resource optimization capabilities of the Qinghai power grid, effectively ensure the transmission of clean energy on a larger scale and in a wider range in Qinghai Province, accelerate the development of energy transformation, continuously consolidate the clean energy consumption and security capabilities, and help Qinghai build a national clean energy industry highland and contribute the wisdom and strength of Qinghai Power. State Grid Qinghai Electric Power Research Institute played a "trilogy" around the commissioning of the power grid phase regulator, which played a role in protecting the safe and stable operation of the Qinghai power grid phase regulator.

"Tough Battle"---Meet challenges head-on and explore new paths

In 2019, State Grid Qinghai Electric Power Research Institute received the task of commissioning the 2×300Mvar phase condensers at the Qaidam Converter Station. Faced with two new equipment and new technologies, the commissioning of the first phase condenser on the plateau was "the first time for a young lady to get married". The Electric Power Research Institute selected senior commissioning experts to form a commissioning team. Through learning and research, hard work and practical work, they formulated a strict commissioning schedule, commissioning plan, defect elimination plan, acceptance plan, safety plan, commissioning work instructions, and organizational guarantees. After a year and a half, more than a thousand defects in design, installation, and manufacturing were discovered and handled, and the phase condenser commissioning task was successfully completed, accumulating valuable experience in technical commissioning, operation and maintenance, and characteristic research of the first set of phase condensers.

With the debugging experience accumulated in the first time, the State Grid Qinghai Electric Power Research Institute undertook and completed the debugging of the 4×300Mvar phase condenser at the Qingnan Converter Station in 2020, and completed the debugging of the new air-cooled salient pole 7×50MVar distributed phase condenser in Hainan Prefecture, Qinghai in 2021. At the same time, at the request of the State Grid, an expert group was sent to provide technical assistance to the first UHV converter station phase condenser in Jiangxi Province and the first 2×100Mvar phase condenser at the Lhasa Converter Station. It took the lead in conducting the investigation of the operating safety and anti-false operation (refusal to operate) hidden dangers of the non-electrical protection device of the phase condenser, and the investigation results were promoted across the national network. At the same time, the analysis and processing of the abnormal vibration protection signal tripping fault of the Qingnan Converter Station and the Qaidam Converter Station and the analysis and processing of the water cut protection tripping accident were completed; actively cooperated with the State Grid Equipment Department to carry out technical research and research on the thermal protection migration of the condenser, the redundant configuration of the vibration protection hardware of the condenser, and the standardization of the thermal protection of the condenser; also completed the special mechanical tests of the condenser stator and rotor of the Qingnan Converter Station, supervised the treatment of the tungsten gold pits and wear problems of the condenser bearings, and supervised and warned the problems of incomplete overhaul projects and non-standard tests. In the past three years, after all-round inspection, debugging and troubleshooting of the condenser body, various subsystems, automatic control, electrical testing, etc., and actively carried out professional management and technical research on the installation, testing, acceptance and debugging of the condenser, not only accumulated a large amount of performance test data, debugging experience, troubleshooting skills and operation and maintenance management experience, but also overcome and solved some condenser equipment design, manufacturing, installation defects and technical problems, and played a technical support role for the safe and stable operation of the condenser in the Qinghai Power Grid.

"Tamping the song"--strengthening the foundation

In 2021, the world's first Qinghai-Henan ±800kV ultra-high voltage DC project, which mainly transmits new energy, was fully completed and put into operation. Phase-shifting phases are the "magic weapon" to ensure the stability of grid voltage, improve the system power supply quality, and enhance the stability of the power system. Studying their operating characteristics, participating in fault diagnosis, and formulating standardized standards to ensure that phase-shifting phases fully play the role of "voltage stabilizer" of the grid is another key task of the State Grid Qinghai Electric Power Research Institute.

"Without rules, there is no order". While undertaking and completing the commissioning tasks of different types of centralized and distributed phase condensers, State Grid Qinghai Electric Power Research Institute has taken the lead in completing the compilation of "Measures of State Grid Corporation to Prevent Phase condenser Accidents" based on phase condenser countermeasures and relevant technical standards, in order to continue to provide technical support for phase condensers in Qinghai Power Grid, standardize the standards and key supervision contents for the key stages of design, acceptance, commissioning, operation and maintenance, and overhaul of each system of Qinghai Power Grid synchronous phase condensers, and participate in the compilation of "Compilation of Typical Defects of Phase condensers of State Grid Corporation"; and take the lead in compiling the compilation of "Technical Supervision Guidelines for Synchronous Phase condensers of Qinghai Power Grid". The formulation of the above specifications fills the gap in the technical specifications of phase condensers of State Grid Corporation and Qinghai Provincial Company.

"There is always a reward for hard work." On December 27, 2021, State Grid Corporation of China sent a "good news" and announced the outstanding experts and consultants of State Grid's phase-shifting power plant in 2021. Two experts from Qinghai Electric Power Research Institute were rated as outstanding experts in phase-shifting power plant maintenance and outstanding experts in excitation, respectively, and were also appointed as the leader and member of the expert group of the State Grid Phase-shifting Technology Center. Qinghai Electric Power Research Institute took advantage of the situation and, in order to play a good role in the technical support of the power grid, promptly studied and prepared to build a phase-shifting power plant technical room, configured the corresponding technical team and expert group, and continued to deepen the research on the development of phase-shifting power plant technical support work.