An adaptive controller for Wolsong NGS bulk liquid zone control of RRS

The study was done to identify the vulnerable devices or control parameters on stability. The time constant of LZC valve was analyzed as the critical parameter among the candidates. With limited simulation results, we have confirmed that no fundamental barriers of RRS bulk control exist for Wolsong 2/3/4. The first order lag term of the actuator, LZC valve, is the most critical among all sensing and actuating devices. With the help of MRAS (model reference adaptive system) regulator in this study, the adaptive controller with an aged actuator has a capability to deal with the worst situation successfully, with which the DCC program could not cope. This study will give guidance for the plant engineer when either tuning is necessary or preventive maintenance is planned against aging. If a fault tolerant control scheme is applied, an unstable operation of the RRS will be relieved from such an unexpected malfunction. We suggest an adaptive controller to follow the Reference Model to cope with the aging and degraded effect of the LZC controller.