SA Ras Al Khair O&M Project Solves HRSG Side BJC Busbar Frequently Auto Switching Problem
There are 10 BJC busbars on the HRSG side of Ras Al Khair Power Plant, so the frequent auto switching problem on BJC has significant influence to the safe and steady operation. Since the GT32 going into commercial operation, the problem of HRG32 distribution room’s BJC incoming switches happened many times.
In order to find out the reason and eliminate the danger, the project set a specific technical team, used the methods of system technical analysis and optimizing LV set value, finally solve the problem within 7 months.
The technical team gathered related commissioning and DCS switch curves, integrated ideas from all parties and proposed the agreed rectification plan. With the project’s approval, the team grasped the opportunity of unit shutdown and checked and rectified the HRSG side BJC control loop.
The team firstly checked the busbars’ incoming switches DCS control interface channel and signals with the I&C staffs, verified the switch closing and command signal, excluded the problem of DCS distance control command leading to switch malfunction.
After that, the electrical staffs fastened all the connectors on control loop and checked the numbers, checked the breakers of control loop, the coil resistance and auxiliary contacts, the voltage transducer input and output signals and the switch condition loop, excluded the related problems.
The team then analyzed the switching phenomena by using the switch curves recorded by DCS and found that when the outside grid fluctuating, the busbars voltage valley value closed to 360V set by voltage supervisory relay. The team changed the set value to 350V to avoid the problem. After optimizing the LV set value, the team tested the BJC switches and simulated one incoming switch black out to test the other incoming switch, the test was successful.
Up to the beginning of August, the team had finished the checking and rectification works for all units’ HRSG side BJC control loop. After that, there was no more incoming switches frequent auto switching problem, which insured the steady operation of HRSG and the ‘Meeting Summer Peak’ work.