DESC:TECHNICAL FIELD
The present disclosure generally relates to systems and methods of electronic circuit fault detection. The present invention specifically relates to a system and a method for early detection of faulty condition; specially short-circuit condition, in an electronic circuit and accurately issuing a trip command to isolate the faulty component or section.

BACKGROUND
Background description includes information that may be useful in understanding the present invention. It is not an admission that any of the information provided herein is prior art or relevant to the presently claimed invention, or that any publication specifically or implicitly referenced is prior art.
In general, every electrical power supply system must be protected against short circuit conditions and other faulty conditions that may harm the system. In industry, in particular for electrical installations or machines, this protection is achieved by protective devices in the form of fuses or circuit breakers or other overload protection devices which are opened via appropriate tripping units during a short circuit condition.
In the event of a short circuit, protective devices such as circuit breaker, first of all limit the current flowing in order to protect both the electrical installations (cables, busbars, etc.) and the connected loads (machines, etc.). The current limiting reduces the electro dynamic loads (resulting from the square of the current) and the thermal loads (resulting from the integral of the square of the current) on an electrical installation during the time of a short circuit. The load depends on the response time of the switch. The response time depends in particular on the time (self response time) which the electronic evaluation unit requires to identify a short circuit.
In many electronic releases, a short circuit is identified by comparing the instantaneous value of the current flowing with a threshold value, and this could take a relatively long time, depending on the nature of the short circuit. In order to reduce the time before identification of a short circuit, it has already been proposed that the gradient of the current curve (first time derivative of the current) be considered as an alternative criterion. This type of tripping responds only to the gradient of the current curve, but not to the current level that is reached. Initially, this criterion was applied only to shorten the switching-off times of quick-action direct-current switches, since the relationship between the rate of current rise, the short-circuit current and the voltage in single-phase and poly-phase systems is dependent on the time of the short circuit and on the power factor in the power supply system.
Short-circuit detection devices that presently exist use current differential signals and real current signals to detect a short circuit. These devices use a non-trip zone represented in an orthogonal coordinates system with a current differential axis and a real current axis. As soon as a passage outside the zone occurs, a short circuit is detected. If a current represented by a differential signal and a real component signal remains inside the zone, there is no short-circuit detection.
The methods used in state-of-the-art devices enable simple short-circuit detection to be achieved, but the speed of decision is not sufficient for very fast detection devices. For certain switchgears, known methods are unable to detect a short circuit where the current is already too high. Such a delay is liable to reduce the performances of a switchgear apparatus such as a circuit breaker.
US Patent No. 6437576 discloses a short-circuit identification method based on estimating the electrical characteristics of the short-circuit load and calculating the peak value of the current on the basis of N successive samples of the instantaneous current and its first derivative. This patent relates to a method which is able to rapidly detect the initiation of short-circuit conditions in an electrical network. In addition to short circuit detection, simultaneous calculation of the short circuit power factor and of the phase of the voltage at the moment of short circuit has also been talked about.
US Patent No. 6313639 and 6844737 discloses method for short-circuit condition detection based on the root locus approach which involves the current and its first and second derivative or any two of them continuously and successively at the same time and are processed as a digital numerical sequence. The basic idea behind these patents is to plot root loci for determination of thresholds, also called ‘limit curves’. Short circuit condition detection is based on the numerical sequences crossing their respective limit curves.
Another literature by Feng Du et. al (Journal of Power and Energy Engineering, 2014, 2, 432-437) discloses detection of a short circuit based on regression method which involves sequence of the current and it’s integral in time for determining the prospective current peak. Short circuit is identified when estimated current peak exceeds the preset threshold.
Major drawbacks associated with the aforementioned prior art documents include involvement of second derivative in determining the current peak, which makes the method more sensitive to high frequency noise and harmonic interference in the current signal, resulting in false detection of short-circuits in electrical networks. Some of the methods disclosed in aforementioned prior art documents are suitable only for sinusoidal signal at a given frequency for a resistive-inductive network and are incapable of precise detection of current level in case of any capacitor switching or transient occurring in the system.
In light of the limitations of the aforesaid prior art documents, there is therefore a need for an improved short-circuit fault prediction method and system that efficiently detects the faults in the microsecond range in electrical power supply systems, and also enables accurate detection of faults in any circuit configuration even in case of capacitor switching and nonlinear loads.
All publications herein are incorporated by reference to the same extent as if each individual publication or patent application were specifically and individually indicated to be incorporated by reference. Where a definition or use of a term in an incorporated reference is inconsistent or contrary to the definition of that term provided herein, the definition of that term provided herein applies and the definition of that term in the reference does not apply.
In some embodiments, the numbers expressing quantities of ingredients, properties such as concentration, reaction conditions, and so forth, used to describe and claim certain embodiments of the invention are to be understood as being modified in some instances by the term “about.” Accordingly, in some embodiments, the numerical parameters set forth in the written description and attached claims are approximations that can vary depending upon the desired properties sought to be obtained by a particular embodiment. In some embodiments, the numerical parameters should be construed in light of the number of reported significant digits and by applying ordinary rounding techniques. Notwithstanding that the numerical ranges and parameters setting forth the broad scope of some embodiments of the invention are approximations, the numerical values set forth in the specific examples are reported as precisely as practicable. The numerical values presented in some embodiments of the invention may contain certain errors necessarily resulting from the standard deviation found in their respective testing measurements.
As used in the description herein and throughout the claims that follow, the meaning of “a,” “an,” and “the” includes plural reference unless the context clearly dictates otherwise. Also, as used in the description herein, the meaning of “in” includes “in” and “on” unless the context clearly dictates otherwise.
The recitation of ranges of values herein is merely intended to serve as a shorthand method of referring individually to each separate value falling within the range. Unless otherwise indicated herein, each individual value is incorporated into the specification as if it were individually recited herein. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g. “such as”) provided with respect to certain embodiments herein is intended merely to better illuminate the invention and does not pose a limitation on the scope of the invention otherwise claimed. No language in the specification should be construed as indicating any non-claimed element essential to the practice of the invention.

OBJECTS OF THE INVENTION
It is an object of the present invention to provide a system and method for early short circuit detection.
It is an object of the present invention to provide an accurate short circuit detection method based on prediction of prospective current peak by regression technique.
A further object of the present invention is to provide for a short circuit detection method that accurately recognizes the fault in any system configuration i.e. even with capacitor switching and non-linear loads.
A further object of the present invention is to provide system and method for a short circuit detection that accurately recognizes the fault in any electrical system avoiding false positives and issues a trip signal only when predicted peak crosses the preset threshold.
Various objects, features, aspects and advantages of the present invention will become more apparent from the detailed description of the invention herein below along with the accompanying drawing figures in which like numerals represent like components.

SUMMARY
The present disclosure generally relates to a system and method for short-circuit detection in electrical circuit. The present invention specifically relates to a system and method for early detection of faulty condition; specially short-circuit condition, in an electronic circuit and accurately issuing a trip command to isolate the faulty component or section.
Aspects of the present disclosure relates to a system and a method for early detection of fault condition, for example short circuit condition, in an electronic circuit that raises a ZSI flag governed by ellipse approach and issues a trip signal when a predicated peak value of current crosses a predefined threshold. The system and method of present disclosure is configured to use regression technique, where N successive samples of the current, its derivative and the integral of current are used as parameters for raising the ZSI flag and issuing the trip signal.
An aspect of the present disclosure relates to a method for detecting fault in an electronic circuit. The method can include the steps of sensing, by a current sensor, the current signal to generate derivatives associated with the of current signal; integrating, by an integrator, the derivatives of the of current signal to obtain the current signal (i(t)); extracting, by an integrator, integral of current signal ? i(??) from the current signal (i(t)); determining, by an length estimation module, radial distance from origin for the root locus of i(t) and ????(??)/????, comparing the radial distance determined with a pre-determined threshold value to identify occurrence of the fault; and determining, by a processing module, a current peak associated with the current signal based on the current signal (i(t)), the integral of current signal ? i(??), and the radial distance to issue the trip signal.
In an aspect, the pre-determined threshold value is associated with maximum radius of an ellipse threshold envelope for each time interval of the current signal. In an aspect, the trip signal is issued if the current peak determined exceeds a pre-determined/ pre-set threshold value for current peak.
In an aspect, if the radial distance determined exceeds the pre-determined/ pre-set threshold value indicates the occurrence of the fault, or if the radial distance determined exceeds the pre-determined threshold value a detection flag, preferably a zone selective interlocking (ZSI), is raised by the length estimation module indicates the occurrence of the fault.
In an aspect, the step of determining can further include determining the values the current signal (i(t)), the integral of current signal ? i(??), and the radial distance to obtain a prospective current peak value; comparing the prospective current peak value with a tripping threshold value of current peak; incrementing a threshold exceed counter every time the prospective current peak value exceeds the tripping threshold value of current peak; and issuing the trip signal to a trip device when the threshold exceed counter exceeds a predefined threshold value.
An aspect of the present disclosure relates to a fault detection system in an electronic circuit. The fault detection system includes a current sensor, an integrator, a length estimation module, and a processing module. In an aspect, the current sensor can sense the current signal to generate derivatives associated with the current signal. The integrator can integrate the derivatives of the of current signal to obtain the current signal (i(t)) and extract integral of current signal ? i(??) from the current signal (i(t)). The length estimation module can determine a radial distance from origin for the root locus of i(t) and ????(??)/????, comparing the radial distance determined with a pre-determined threshold value to identify occurrence of the fault, wherein the pre-determined threshold value is associated with maximum radius of an ellipse threshold envelope for each time interval of the current signal. The processing module determine a current peak associated with the current signal based on the current signal (i(t)), the integral of current signal ? i(??), and the radial distance to issue the trip signal, wherein the trip signal is issued if the current peak determined exceeds a pre-determined/ pre-set threshold value for current peak.
An aspect of the present disclosure relates to a method for detecting short-circuit condition in an electrical circuit including the steps of:
Determining, for an electronic circuit, values of a current flowing and its first derivative taken at successive time intervals, for example at time t, t+ 1, t+2, and likewise for t+(N-1);
calculating radial length of root locus for each successive sample from origin;
comparing the calculated radial length to a predefined max radius of an ellipse threshold envelope at each time interval; and
raising zone selective interlocking (ZSI) detection flag, indicative of potential fault condition, when the calculated radial lengths breach the ellipse threshold for N successive samples.
In an aspect, the method can further includes the steps of detecting prospective current peak and issuing a trip signal to a trip device in an electronic circuit. The step of detecting prospective current peak and issuing trip signal includes sub-steps of:
determining the values of three input parameters including current flowing in the electronic circuit, its first derivative and integral of the current for N successive samples, wherein the successive samples are taken at a particular frequency (or time interval);
comparing the prospective current peak with a tripping threshold value of current peak;
incrementing a threshold exceed counter every time the prospective current peak exceeds the tripping threshold value of current peak;
issuing a trip signal to the trip device when the threshold exceed counter exceeds a predefined threshold value.
In an aspect, the detection of prospective current peak and issuance of trip signal is initiated when the ZSI detection flag is raised.
In an aspect, the present disclosure provides an improved ZSI coordinated distribution system to limit stress on the electronic circuit by reducing the time it takes to clear the fault.
Various objects, features, aspects and advantages of the present invention will become more apparent from the detailed description of the invention herein below along with the accompanying drawing figures in which like numerals represent like components.

BRIEF DESCRIPTION OF THE DRAWINGS
The accompanying drawings are included to provide a further understanding of the present disclosure, and are incorporated in and constitute a part of this specification. The drawings illustrate exemplary embodiments of the present disclosure and, together with the description, serve to explain the principles of the present disclosure.
FIG. 1 illustrates an exemplary schematic diagram of a power system network consisting of RLC load along with shunt capacitor switching in accordance with embodiments of the present disclosure.
FIG. 2 illustrates an exemplary block diagram for short circuit detection in accordance with an embodiment of the present disclosure.
FIG. 3 illustrates exemplary flow of a method for detecting fault condition and issuing trip signal in accordance with embodiments of the present disclosure.

DETAILED DESCRIPTION OF THE INVENTION
Unless the context requires otherwise, throughout the specification and claims which follow, the word “comprise” and variations thereof, such as, “comprises” and “comprising” are to be construed in an open, inclusive sense that is as “including, but not limited to.”
Reference throughout this specification to “one embodiment” or “an embodiment” means that a particular feature, structure or characteristic described in connection with the embodiment is included in at least one embodiment. Thus, the appearances of the phrases “in one embodiment” or “in an embodiment” in various places throughout this specification are not necessarily all referring to the same embodiment. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner in one or more embodiments.
As used in the description herein and throughout the claims that follow, the meaning of “a,” “an,” and “the” includes plural reference unless the context clearly dictates otherwise. Also, as used in the description herein, the meaning of “in” includes “in” and “on” unless the context clearly dictates otherwise.
The headings and abstract of the disclosure provided herein are for convenience only and do not interpret the scope or meaning of the embodiments.
Reference will now be made in detail to the exemplary embodiments of the present disclosure, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers are used in the drawings and the description to refer to the same or like parts.
The following discussion provides many example embodiments of the inventive subject matter. Although each embodiment represents a single combination of inventive elements, the inventive subject matter is considered to include all possible combinations of the disclosed elements. Thus if one embodiment comprises elements A, B, and C, and a second embodiment comprises elements B and D, then the inventive subject matter is also considered to include other remaining combinations of A, B, C, or D, even if not explicitly disclosed.
The present disclosure generally relates to a system and method for short-circuit detection in electrical circuit. The present invention specifically relates to a system and method for early detection of faulty condition; specially short-circuit condition, in an electronic circuit and accurately issuing a trip command to isolate the faulty component or section.
Aspects of the present disclosure relates to a system and a method for early detection of fault condition, for example short circuit condition, in an electronic circuit that raises a ZSI flag governed by ellipse approach and issues a trip signal when a predicated peak value of current crosses a predefined threshold. The system and method of present disclosure is configured to use regression technique, where N successive samples of the current, its derivative and the integral of current are used as parameters for raising the ZSI flag and issuing the trip signal.
An aspect of the present disclosure relates to a method for detecting fault in an electronic circuit. The method can include the steps of sensing, by a current sensor, the current signal to generate derivatives associated with the of current signal; integrating, by an integrator, the derivatives of the of current signal to obtain the current signal (i(t)); extracting, by an integrator, integral of current signal ? i(??) from the current signal (i(t)); determining, by an length estimation module, radial distance from origin for the root locus of i(t) and ????(??)/????, comparing the radial distance determined with a pre-determined threshold value to identify occurrence of the fault; and determining, by a processing module, a current peak associated with the current signal based on the current signal (i(t)), the integral of current signal ? i(??), and the radial distance to issue the trip signal.
In an aspect, the pre-determined threshold value is associated with maximum radius of an ellipse threshold envelope for each time interval of the current signal. In an aspect, the trip signal is issued if the current peak determined exceeds a pre-determined/ pre-set threshold value for current peak.
In an aspect, if the radial distance determined exceeds the pre-determined/ pre-set threshold value indicates the occurrence of the fault, or if the radial distance determined exceeds the pre-determined threshold value a detection flag, preferably a zone selective interlocking (ZSI), is raised by the length estimation module indicates the occurrence of the fault.
In an aspect, the step of determining can further include determining the values the current signal (i(t)), the integral of current signal ? i(??), and the radial distance to obtain a prospective current peak value; comparing the prospective current peak value with a tripping threshold value of current peak; incrementing a threshold exceed counter every time the prospective current peak value exceeds the tripping threshold value of current peak; and issuing the trip signal to a trip device when the threshold exceed counter exceeds a predefined threshold value.
An aspect of the present disclosure relates to a fault detection system in an electronic circuit. The fault detection system includes a current sensor, an integrator, a length estimation module, and a processing module. In an aspect, the current sensor can sense the current signal to generate derivatives associated with the current signal. The integrator can integrate the derivatives of the of current signal to obtain the current signal (i(t)) and extract integral of current signal ? i(??) from the current signal (i(t)). The length estimation module can determine a radial distance from origin for the root locus of i(t) and ????(??)/????, comparing the radial distance determined with a pre-determined threshold value to identify occurrence of the fault, wherein the pre-determined threshold value is associated with maximum radius of an ellipse threshold envelope for each time interval of the current signal. The processing module determine a current peak associated with the current signal based on the current signal (i(t)), the integral of current signal ? i(??), and the radial distance to issue the trip signal, wherein the trip signal is issued if the current peak determined exceeds a pre-determined/ pre-set threshold value for current peak.
In an aspect, a method for detecting short circuit condition in an electronic circuit includes the steps of, determining, for an electronic circuit, values of a current flowing and its first derivative taken at successive time intervals, for example at time t, t+1, t+2, and likewise for t+(N-1), calculating radial length for root locus of current and its derivative at each time interval from origin , comparing the calculated radial lengths to a predefined max radius of an ellipse threshold envelope, and raising zone selective interlocking (ZSI) detection flag, indicative of potential fault condition, when the calculated radial lengths breach the ellipse threshold for N successive samples. Once the ZSI detection is raised, the method further includes the steps of detecting prospective current peak and issuing trip signal to a tripping device in an electronic circuit. In an exemplary implementation, the step of detecting prospective current peak and issuing trip signal includes sub-steps of, a) determining the values of three input parameters including current flowing in the electronic circuit, its first derivative and integral of the current at each time interval, wherein the successive samples are taken at a particular frequency (or time interval) using, for example a DSP controller, comparing the prospective current peak with a tripping threshold value of current peak, incrementing a threshold exceed counter every time the prospective current peak exceeds the tripping threshold value of current peak, and issuing a trip signal to the tripping device when the threshold exceed counter exceeds a predefined threshold value.
As described above, the present invention provides an early short circuit detection method to be used in electronic circuit(s). The method includes the following two stages: (a) detection of short-circuit that relies on the sudden change in the current level and its derivative, and (b) prediction of RMS (or estimated peak current) of a current signal.
Under normal operating condition, the root locus of i(t) and (di(t)/dt) lies inside a threshold envelope. The threshold envelope for detection can be formed by encompassing all the loci into two intersecting ellipses. The envelope boundary is the maxima of the radii of the two intersecting ellipse.
The radius of the ellipse can be given by:

Where, a, b are the intercepts of the ellipse.
In a non-limiting embodiment, the detection is carried out when radius at any instant of root locus exceeds the threshold envelope for N successive samples. A ZSI flag is raised when the root locus exceeds the threshold envelope for N successive samples. As one may appreciate, the trip signal is not generated at this stage to avoid the false positive. In an exemplary implementation, trip signal can be issued when estimated/predicted RMS (peak value) breaches the predefined RMS threshold. The challenge is to discriminate between normal transients (during switching operations like load switching on and off, motor loads etc.) from the fault condition.
An exemplary schematic diagram of a power system network consisting RLC load along with shunt capacitor switching is shown in the FIG. 1. As shown in FIG. 1, a circuit breaker 100 is provided with an electronic tripping unit, for example a switch 104. A shunt capacitor 106 can be connected with a resistor, inductor and capacitor (RLC) network through a switch 104. Current from source 102 can be monitored and trip signal can be generated in accordance with an embodiment of the present disclosure to protect the circuit using switch 104. In an exemplary implementation, differential equations for switching-on process of the single-phase RLC circuit at a given frequency ? can be derived from the equivalent circuit at a rated voltage (root mean square value) v as a function of the time t:
V_m cos?(?t+f)= Ri + L di/dt + 1/C ?_0^t¦idt
The above system equation can be solved for current i(t) and can be written in matrices form as:
[i(t)]= [? X Y Z][¦(A@B@C@D)]
Figure 2 shows exemplary block diagram for carrying out the method for early short circuit detection in an electrical network. In an exemplary implementation, a Rogowski coil 202 can preferably be used as a current sensor that outputs derivative of current signal. The output signal from the Rogowski coil can be numerically integrated by an integrator 204 to obtain the current signal (i(t)). The current signal obtained is further integrated by an integrator 206 to extract integral of current signal ? i(??). These signals are then fed to the stage 1 block 208 and the calculation of radial distance r from origin for the root locus of i(t) and ????(??)/???? is carried out and a detection flag is raised when the calculated r exceeds the ellipse threshold envelope for N consecutive samples. Flag raising is preliminary information of the fault so the trip signal is issued when the condition is satisfied for the 2nd stage. The evaluation of current peak is carried out within processing block 210 using the formula given by the following equation, and whenever the estimated current peak exceeds the preset threshold, the trip signal is issued by the tripping unit 212.
I_peak= v((Y^2+Z^2)/(1+ ?(X-?)?^2 ))
The flow chart for the present invention is given in FIG. 3. The present algorithm involves two stages:
estimation of radial length of root locus for detection and
estimation of prospective current peak for tripping
In an exemplary implementation, the Radial length r can be calculated on the basis of the current i(t), its first derivative determined successively at the same time. The integral of current along with the two inputs (current value and first derivative) can be used for peak computation/estimation and trip signal generation.
Since the Rogowski coil produces derivative of current as the output, the current i can be determined by numerical or digital integrator, and the integral of current can be measured by further feeding the current sequence to another digital integrator. High frequency filtering can be carried out prior to the digitizing process to compensate for the errors resulting from numerical integration. The detection method can be closely associated with the digital interface.
The numerical sequences thus obtained can be fed to the input channels of the processing unit of stage 1 where radial length can be calculated for each instance and obtained radius can then be compared to predefined max radius of the threshold envelope. Detection flag can be raised when the r breaches the threshold for successive samples, for example 10 successive samples. Once the short circuit is detected, ZSI flag can be raised and a signal can be sent for the estimation of current peak (stage 2). This involves four successive samples of each of the three input parameters for estimation of prospective current peak using DSP controller. Sampling can be carried out at a preferred frequency to achieve the desired result. Estimated current peak can then be compared with the first threshold (i.e. tripping threshold). Every time the estimated current peak exceeds the set threshold, the threshold exceed counter is incremented. The comparison process can continue till the counter value exceeds a predefined numerical value, for example 3. Threshold for the current peak can be chosen such that the detection takes place when the estimated current peak exceeds the set threshold for at least three successive times to prevent the system from nuisance tripping which could arise in the case of any capacitor switching or transient occurring in the system.
In an exemplary embodiment, the process, function and /or operations performed in stage 1 and stage 2 as discussed in this disclosure may be performed by analog /op-amp based circuitry along with the microcontroller/ DSP. However, it would be appreciated that any device having capabilities like analog /op-amp based circuitry along with the microcontroller / DSP for can be use to perform the present invention.
FIG. 3 illustrates exemplary flow of a method for detecting fault condition and issuing trip signal in accordance with embodiments to the present disclosure. The method includes steps of acquiring value of current signal as shown at step 304, and computing its numerical integration for N successive samples as shown at step 306. The method includes the step of determining root locus using current i and derivative di/dt as shown at step 308 and calculating radial distance R from the origin as shown at step 310. At step 312, comparison is made to determine whether the R is greater than a root locus value threshold Rth of a threshold envelop. If R> Rth, a counter c can be incremented by 1, as shown at step 314, and a ZSI flag, indicative of potential fault condition, can be raised if counter value C is greater than counter threshold. In an exemplary implementation, the method include step 324 of calculating estimated peak value of current (Ipeak), taking current value, its first derivative and integral of N successive samples calculated at step 320, comparing Ipeak with peak threshold value (Ith) as shown at step 326 and generating a trip signal when Ipeak exceeds the Ith for a predefined peak exceed threshold count as shown at step 328.
In an exemplary implementation, a method for detection of fault condition can include steps of detecting sudden change in the current level and its derivatives, calculating predicated peak value (RMS of current signal) for N successive samples and generating a trip signal when the calculated predicated peak value exceeds a predefined threshold peak value.
In an exemplary implementation, a digital signal processing (DSP) controller that allows high end processing for sophisticated control logic can be used to enable reliable fault detection. It can also be used to sample the signals at high frequency (about 20 KHz or higher) for faster detection and can support high end filtering to make the method and system of present disclosure less sensitive to noisy signal (derivative of current in particular). As one may appreciate, the fault condition detection method and system of the present disclosure can work for any circuit arrangement and load. In an exemplary implementation, more than one current sensor can be used to avoid loss of data due to delay in sensing or signal processing.

ADVANTAGES OF THE INVENTION
The invention provides for an early short circuit detection method based on ZSI coordinated distribution system.
The invention provides for an improved ZSI coordinated distribution system that uses ellipse approach for short circuit detection to limit fault stress on the system.
The invention provides for an accurate short circuit detection method based on prediction of prospective current peak by regression technique.
The invention provides for a regression technique that involves N successive samples of three input parameters - the current, its derivative and the integral of current for utilization in short circuit detection method.
The invention provides for a short circuit detection method that accurately recognizes the fault in any system configuration i.e. even with capacitor switching and non-linear loads.
The invention provides for a short circuit detection method that accurately recognizes the fault in any electrical system by issuing a trip signal only when predicted peak crosses the preset threshold for at least three successive times.
,CLAIMS:1. A method for detecting fault in an electronic circuit, the method comprising:
sensing, by a current sensor 202, the current signal to generate derivatives associated with the current signal;
integrating, by an integrator 204, the derivatives of the of current signal to obtain the current signal (i(t));
extracting, by an integrator 206, integral of current signal ? i(??) from the current signal (i(t));
determining, by a length estimation module 208, radial distance from origin for the root locus of i(t) and ????(??)/????, comparing the radial distance determined with a pre-determined threshold value to identify occurrence of the fault; and
determining, by a processing module 210, a current peak associated with the current signal based on the current signal (i(t)), the integral of current signal ? i(??), and the radial distance to issue the trip signal 212.

2. The method as claimed in claim 1, wherein the pre-determined threshold value is associated with maximum radius of an ellipse threshold envelope for each time interval of the current signal.

3. The method as claimed in claim 1, wherein if the radial distance determined exceeds the pre-determined/ pre-set threshold value indicates the occurrence of the fault.

4. The method as claimed in claim 1, wherein if the radial distance determined exceeds the pre-determined threshold value a detection flag, preferably a zone selective interlocking (ZSI), is raised by the length estimation module 208 indicates the occurrence of the fault.

5. The method as claimed in claim 1, wherein the trip signal 212 is issued if the current peak determined exceeds a pre-determined/ pre-set threshold value for current peak.

6. The method as claimed in claim 1, wherein the step of determining further comprises:
determining the values the current signal (i(t)), the integral of current signal ? i(??), and the radial distance to obtain a prospective current peak value;
comparing the prospective current peak value with a tripping threshold value of current peak;
incrementing a threshold exceed counter every time the prospective current peak value exceeds the tripping threshold value of current peak; and
issuing the trip signal 212 to a trip device when the threshold exceed counter exceeds a predefined threshold value.

7. A fault detection system in an electronic circuit, comprising:
a current sensor 202 adapted to sense the current signal to generate derivatives associated with the current signal;
an integrator 204, 206 adapted to:
integrate the derivatives of the of current signal to obtain the current signal (i(t));
extract integral of current signal ? i(??) from the current signal (i(t));
a length estimation module 208 adapted to determine a radial distance from origin for the root locus of i(t) and ????(??)/????, comparing the radial distance determined with a pre-determined threshold value to identify occurrence of the fault, wherein the pre-determined threshold value is associated with maximum radius of an ellipse threshold envelope for each time interval of the current signal; and
a processing module 210 adapted to determine a current peak associated with the current signal based on the current signal (i(t)), the integral of current signal ? i(??), and the radial distance to issue the trip signal 212, wherein the trip signal 212 is issued if the current peak determined exceeds a pre-determined/ pre-set threshold value for current peak.

8. The fault detection system as claimed in claim 7, wherein the length estimation module 208 is further adapted to indicate the occurrence of the fault if:
if the radial distance determined exceeds the pre-determined/ pre-set threshold value; or
if the radial distance determined exceeds the pre-determined threshold value a detection flag, preferably a zone selective interlocking (ZSI).

9. The fault detection system as claimed in claim 7, wherein processing module 210 is further adapted to:
determine the values the current signal (i(t)), the integral of current signal ? i(??), and the radial distance to obtain a prospective current peak value;
compare the prospective current peak value with a tripping threshold value of current peak;
increment a threshold exceed counter every time the prospective current peak value exceeds the tripping threshold value of current peak; and
issue the trip signal 212 to a trip device when the threshold exceed counter exceeds a predefined threshold value.