Interturn Faults Detection of Transformers by Diagnosis of Neutral Current

Abstract

 Abstract-Interturn short circuit faults are the leading cause of power transformer's failure. If not detected at incipient stage, these faults usually develop into more severe faults that would result in irreversible damage to the transformer, unexpected outages and the consequential losses. This paper presents transformer interturn fault detection system (TIFDS) for the detection of interturn fault at inception stage in power transformer. TIFDS is immune to supply voltage imbalance, constructional asymmetries and instrumental errors. It also takes care of unequal load distribution. TIFDS algorithm makes the transformer symmetrical in its entire three phases and sets primary side neutral current to zero value. This is achieved by computing and applying various correction coefficients. However, under interturn fault condition, TIFDS characterizes the behavior of neutral current. Simulation and experimentation studies are carried out on 400/110V, 3x2.5 kVA power transformer. Presented test results demonstrate the effectiveness of the proposed system.Index Terms--Interturn fault, Neutral current, Transformer, Transformer interturn fault detection system (TIFDS).

Power transformers monitoring based on electrical measurements: state of the art

“…Analysis with no-load or low load [61] relay: negative sequence currents 1% turns short circuited (4 turns) Results not generalised (they treated a particular configuration and a single condition of the system) [57] fuzzy logic 1, 3, 5, 10, 15, and 25% turns short circuited Simple and robust but requires expert criteria. Detects incipient faults in an early stage [36] negative sequence components 1% turns in dead short-circuit Serious fault condition [43] adaptation of conventional differential protection 1% turns in dead short-circuit or more It is not applicable to detect faults in the incipient stage [58] relay: negative sequence currents 1% turns short-circuited (2 turns) Evaluated for different operating conditions, numbers of turns in short circuit, and different connections of the power transformer [69] neutral current of the primary side 4 turns short-circuited Immune to supply voltage unbalance, constructive asymmetries, and instrumental errors and unequal distribution [82,83] ΔV-I 1 locus 2 turns short-circuited Small variations make difficult to realise the fault [96] phase difference between U 1 and I 1 1 or 2 turns short-circuited Applicable only with no-load (and low power factor). Next step: operation with load and with OLTC measurement of currents in an online manner, although their calculation and response time depends on the failure.…”

“…The main characteristic of this method of faults detection by means of the use of components of negative sequence is that it does not depend on the load or disturbances such as unbalanced loads, unbalanced supply voltages, and external short circuits. On the other hand, the technique is immune to constructive asymmetries and measurement errors [58,68,69].…”

Turn-to-turn fault monitoring methods in electrical power transformers-State of the art

“…The requirement here is that the supply voltage harmonics should be in the specified IEEE limits. A coefficient calculation method using primary current and voltage data has been proposed in Ballal et al The algorithm calculates the coefficients for healthy condition, and during online application, it monitors the calculated neutral current to identify the presence of TTF. However, the method requires prior knowledge of load profile.…”

Frequency and time fault diagnosis methods of power transformers

“…Fault diagnosis of power transformers using dissolved gas analysis was presented in the literature [3]- [7]. Electrical parameters of transformers were analyzed [8]- [10]. Signal processing and classification methods were also used for proper fault diagnosis of transformers [11]- [14] and other types of machines [15]- [18].…”