Applicability of linear models in modeling dynamic behavior of alkaline water electrolyzer stack

Linear equivalent circuit models are commonly used to estimate the effect of current ripple on the performance of water electrolyzers, thus it is important that the validity of this approach is examined. The effect of the amplitude and frequency of the sinusoidal current ripple on the performance of the alkaline water electrolyzer stack is studied experimentally. The increased current ripple amplitude produces additional losses in the electrolyzer stack, while the effect of ripple frequency appears to be insignificant. Linear models based on an equivalent circuit and polarization curve tangent are compared with waveform measurements with differing ripple amplitudes and frequencies to study their dynamic modeling capabilities. Under dynamic operation the experimental results show that operating voltage differs considerably from the static polarization curve, especially at low operating currents, due to nonlinear behavior. It is also shown that the dynamic equivalent circuit model using only linear components is not enough to accurately model electrolyzer behavior under dynamic operation. •Effect of power quality on the alkaline electrolyzer is experimentally studied.•Power consumption increases as a function of current ripple amplitude.•Current ripple frequency does not have an observable effect on the stack performance.•Randles equivalent circuit model is studied under dynamic operation.•Tangent based approximations are developed based on the observations.