Abstract: The present invention relates to a method for determining the state of an electrochemical reactor (1), having the steps of: operating an electrode section (2) of the electrochemical reactor (1) for the purpose of generating a harmonic current and voltage signal by means of the electrode section (2), and estimating the amplitude and/or phase of the harmonic current and voltage signal in a model-based manner, wherein the state of the electrochemical reactor (1) is determined on the basis of the estimation, wherein a recursive, time-series-based method is used to estimate the amplitude and/or phase of the harmonic current and voltage signal. The invention also relates to a diagnostic system (3), to a computer program product (5) and to a storage means (6).

Abstract: The present invention relates to a method for determining the state of an electrochemical reactor (1), having the steps of: operating an electrode section (2) of the electrochemical reactor (1) for the purpose of generating a harmonic current and voltage signal by means of the electrode section (2), and estimating the amplitude and/or phase of the harmonic current and voltage signal in a model-based manner, wherein the state of the electrochemical reactor (1) is determined on the basis of the estimation, wherein a recursive, time-series-based method is used to estimate the amplitude and/or phase of the harmonic current and voltage signal. The invention also relates to a diagnostic system (3), to a computer program product (5) and to a storage means (6).

Abstract: Aspects of the disclosure are directed to a technical system modelled as a Volterra series with Volterra kernel (Hn(?1 . . . , ?n)). In a fault-free state of the technical system a Volterra kernel (Hn,nom(?1, . . . , ?n)) of the nth order is determined for the fault-free state. For a defined fault state of the technical system a Volterra kernel (Hn,fault(?1, . . . , ?n)) of the nth order is determined for the fault state. An evaluation kernel (Hn,diff(?1 . . . , ?n)) of the nth order is determined as a function of the Volterra kernel (Hn,nom(?1, . . . , ?n)) of the nth order for the fault-free state and of the Volterra kernel (Hn,fault(?1, . . . , ?n) of the nth order for the fault state. The evaluation kernel (Hn,diff(?1 . . . , ?n)) of the nth order is evaluated to determine a frequency range in which the amplification of the evaluation kernel (Hn,diff(?1 . . . , ?n)) exceeds a predefined limit value and an excitation frequency (?m) is selected from this range for an excitation signal (a(t)).