“Wah, wah, wah…” The alarm in the central control room rings out with shrill urgency as red lights on the control panel flash insistently. Alert messages begin to fill the monitor screen signalling a power failure at the flood gates, a malfunction of dam control equipment, and an interruption in the 10kV power transmission lines.
Deputy plant manager of Jiangbian Hydro Power Station Hu Quan looks intently at the panel to decipher the avalanche of signals and messages. He then picks up his wireless device and delivers a calm message to emergency staff in the dam duty room: “Transmit the reservoir water level information to central control.”
The meter shows the reservoir has reached dangerous levels, meaning the rising water will breach the embankment if the flow continues. Minutes later, Hu breathes a sigh of relief as he receives a reassuring response from the emergency staff. “Back-up diesel power generator operating normally. No 1 and 2 flood gates open. Equipment back to normal.”
It may sound like the plot of a TV drama but in fact this was the scene of an emergency drill held in May at Jiangbian, CLP’s largest hydro power station in Mainland China. The 330MW power station, located in an alpine valley in Jiulong county of Sichuan province, is exposed to flooding, mudslide, and landslide risks during the rainy season from June to October. To make sure employees are prepared at all times for sudden crises, about 20 drills are held every year simulating different emergencies.
For Hu, the drill has a special significance. “It reminds me of the incident four years ago which I still remember vividly today,” he says.
On 29 August 2014, Jiangbian was cut off from the outside world by landslides after days of downpours. It was impossible to assess the damage because the road to the dam was blocked by huge boulders. Hu was duty leader but he was unable to contact the dam duty staff from the central control room and was deeply worried for their safety.
The plant was effectively shut down as the base tower of a 220kV transmission line had collapsed, cutting off power transmission. No one was injured but it took almost a month before the station returned to normal operations.
“Even though we got safely through that crisis, there were lessons to be learned,” says Hu. “We worked hard to identify our deficiencies, and changed our mindset to focus more on prevention to ensure the safety and reliable operation of the plant. Thankfully, we were able to maintain a high reliability standard and have not experienced any unplanned outages since.”
Hu and his team have put in place solutions and upgrades over the past four years, including a three-way wireless communication system connecting the central control room, the security room, and the dam duty room to maintain real-time communication at all times even if the external network breaks down.
In addition, the automatic control system for the flood gates has been upgraded. The back-up diesel power generator now automatically powers up the flood gates to discharge water when control is lost due to power failure. Meanwhile, the power station has introduced automatic cleaning machines to remove floating objects from the reservoir, greatly improving efficiency and ensuring the safe operation of the power generators.
In the process of improving operational reliability, Jiangbian often relies on its own engineers to devise solutions since most of its system software and control processes are not commonly used in the industry. The engineers sometimes spend weeks working with the suppliers to deliver unique solutions.
Jiangbian plant manager Wu Xun says that although there has been no major incident in the past four years, prevention is the best guarantee of safety and reliability.
The station has enhanced its landslide monitoring and alarm systems to provide real-time data and early warnings. It also has its own ambulance and fire engine and a volunteer fire brigade. A health consultant has been appointed to advise employees on daily health issues and first aid.
“It is important for us to cultivate a vigilant attitude and to constantly improve our preventive measures so that we are always prepared for the unexpected,” Wu says.
Albeit satisfied with the drill results, Hu, together with his team at the Jiangbian plant, never lets his guard down. Before leaving the central control room, he quickly makes a note in his diary: “Post-drill evaluation to be scheduled.”