China has developed a world-first high-voltage synchronous condenser, reviving a century-old grid stabiliser technology to support the country’s rapid transition to renewable energy, according to a state media report.
The state-run China Electric Power News said on April 10 that a 35-kilovolt direct-connection rotating machine developed by Dongfang Electric Machinery had successfully passed testing earlier that day.
The successful test made Dongfang’s synchronous condenser the first in the world to reach such a high voltage, eliminating the need for intermediate step-up transformers to achieve direct grid connection, the report said.
The achievement comes at a time when China is undergoing an unprecedented renewable energy transition, spurred by its dual goals of reaching peak carbon emissions by 2030 and achieving carbon neutrality by 2060.
This has been driven by the rapid installation of wind and solar power, particularly in the country’s northern and western regions, with their abundant natural energy resources.
Synchronous condensers were first used in the 1920s to handle the unused reactive power that oscillates between source and load in hydroelectricity generation, according to energy equipment manufacturer GE Vernova.
Essentially large rotating machines used to stabilise fluctuating voltages, synchronous condensers fell out of use as technology developed and reactive power was increasingly handled by semiconductor-based systems.
But the rapid expansion of distributed renewable energies – namely wind and solar power – is presenting challenges to grids that were built to handle more centralised energy sources.
These challenges include intermittency, as power generation from renewables fluctuates because of inconsistent weather, and the decrease in inertia, or resistance to sudden changes in flow, compared with traditional fossil fuel-based and nuclear power plants.
“Without adequate inertia and reactive power support, grids face increased risks of frequency fluctuations, voltage instability, and potential blackouts,” technology corporation ABB said.
The power industry has returned to synchronous condensers because of their ability to handle reactive power, inertia and short-circuits all at once, according to energy technology company Baker Hughes.
Conventional synchronous condensers rely on step-up transformers, which act as adaptors for voltage mismatches but require more devices to be connected to the grid for stable renewable energy delivery.
China Electric Power News reported that the Chinese team was able to develop a high-voltage unit that bypassed the need for step-up transformers and surpassed the previous limit of 27kV.
Dongfang partnered with several institutions, including Tsinghua University and the China Electric Power Research Institute, to overcome the technical challenges of insulation and cooling at high voltage levels, it said.
The team’s 35kV synchronous condenser can provide the same short-circuit capacity as two conventional distributed units, while consuming only 45 per cent of the power used by existing distributed condensers with the same short-circuit capacity.
By eliminating the need for step-up transformers, the team’s units allow for the use of fewer devices, reducing the cost of operation and maintenance by 50 per cent, according to the report. -- SOUTH CHINA M ORNING POST
