Customer Needs
State Grid Corporation of China (SGCC) is the biggest power grid in China including more than twenty provincial grids. Liaoning power grid is one of them with many heavy industry loads. Donganshan 220kV substation, located in Liaoning province, is a typical substation feeding both heavy industry plants and normal residential areas with the needed electric power.
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Blue curve 66kV Busbar 24h Voltage on May 26th 2008
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Red curve 66kV Busbar 24h Voltage on May 27th 2008
Those heavy industry loads vary randomly all day long with caused big voltage fluctuations which can be observed in the 24h voltage curves as illustrated above. The difference between the highest and lowest voltage within a day can reach up to 10% of the nominal voltage, which made the adjacent residential areas suffering every day.
RXPE Solution
Based on a mutual system study with SGCC, it was proposed that a 66kV directly connected SVC can successfully solve the voltage problem. SVC capacity was finally designed as 140Mvar with TCR, FC and existing MSC branches that were controlled by a common C&P system. This project had made the Donganshan SVC valve become the first 66kV thyristor valves in China.
The TCR thyristor valves were based on LTT thyristors and designed as vertical layout with water/air cooling method. Redundant circulating pumps and redundant control & protection system were designed to achieve high stability and easy maintenance. SVC major control algorithm was designed as constant voltage strategy to maintain a stable voltage at the 66kV busbar.
Customer Benefits
Fig-1 66kV bubar 24h voltage without SVC
Fig-2 66kV busbar 24h voltage with SVC
Donganshan SVC had been commissioned in the year 2009. SGCC measured and compared the 24h voltages at both 220kV and 66kV busbars at the substation, which shows the SVC had successfully solved the voltage fluctuation problem. Adjacent residential areas do not need to suffer from the unstable voltage supply any longer.
Liaoning Rongxin Xingye Power Tech Co., Ltd
108 Keji Rd., Anshan 114051 China
Email: overseas@yxlhw.com
