An intelligent and cost-effective method for single-phase fault location in conventional distribution systems

Abstract

Fault location in medium voltage (MV) electricity distribution networks has always been a challenge, in particular, for the last few years. The existence of information only at the beginning of the feeder and the complexity of the widespread and scattered distribution networks make fault location of MV distribution networks a difficult task. The performance of most of the existing methods for fault location is compromised when dealing with today’s MV distribution grid. In this paper, a new fault location method is introduced for MV distribution networks, using transient frequency analysis. The transient caused by fault in the network is analyzed. The main idea of fault location algorithm is to determine and measure the Analysis Index. The location of fault is identified through the relationship between the proposed Analysis Index and different sections in the distribution feeder. In order to evaluate and analyze the proposed method, at first a standard IEEE 11-node network is simulated and tested in MATLAB software, then the same procedure is repeated for a real 69-node network. The results confirm a good performance.

Appendices

Appendix 1: Nomenclature

DN:

Distribution network

$V_{{S_{a} }}$ :

Voltage of phase a at the beginning of section

$V_{{sa_{r} }}$ :

Real part of voltage of phase a at the beginning of section

$V_{{sa_{i} }}$ :

Imagine part of voltage of phase a at the beginning of section

$I_{{S_{a} }}$ :

Current of phase a at the beginning of section

$I_{{L_{a} }}$ :

Current of phase a at the end of section (load current)

$I_{{a_{r} }}$ :

Real part of current of phase a at the beginning of section

$I_{{a_{i} }}$ :

Imagine part of current of phase a at the beginning of section

$I_{\text{f}}$ :

Fault current at the fault point

$I_{a}$, $I_{b}$, $I_{c}$:

Phasor current of phase a, b, c

$I_{{L_{a} }}$ :

Load current or fault downstream current of phase a

x :

Fault distance

$R_{\text{f}}$ :

Fault resistance

$Z_{{Laa_{r} }}$ :

Real part of self-line impedance of phase a

$Z_{{Laa_{i} }}$ :

Imagine part of self-line impedance of phase a

$Z_{{Lab_{r} }}$ :

Real part of mutual impedance of phase a, b

$Z_{{Lab_{i} }}$ :

Imagine part of mutual impedance of phase a, b

$Z_{{Lac_{r} }}$ :

Real part of mutual impedance of phase a, c

$Z_{{Lac_{i} }}$ :

Imagine part of mutual impedance of phase a, c

V(t):

Time domain voltage

$v_{{a{\text{f}}}} = \left| {{\text{FFT}}\left( {v_{a} } \right)} \right|$ :

Absolute value of frequency Fourier transform (FFT) of the fault voltage waveform

$\alpha = v_{{a{\text{f}}}} = |{\text{FFT}}(v_{a} \left( {t_{1} :t_{2} } \right)|$ :

Characteristic factor of each branch

v _a :

Voltage of the phase in which fault has occurred

t ₁ :

Time at which fault starts

t ₂ :

Time at which transient data fault reach to steady state

α _r :

Characteristic factor extracted from real fault (using voltage stored at the feeder at the beginning of feeder)

α _s :

Characteristic factor extracted from feeder branches (through simulation and theoretical calculations)

$\aleph_{{{\text{s}}_{i} }}$ :

Analysis Index of the proposed method for a distribution system with n branches

α _r :

Characteristic factor extracted from real fault which has occurred in the sample system

$\alpha_{{{\text{s}}_{i} }}$ :

Characteristic factor extracted from sample feeder branches no. i

$\aleph_{{{\text{s}}_{\text{sum}} }}$ :

A symbol to show the used index in the proposed method that functions based on comparison

$\aleph_{{{\text{s}}_{{{\text{norm - }}2}} }}$ :

A symbol to show the used index in the proposed method that functions based on second norm

$m_{i}$ :

A symbol to show the difference between the absolute frequency transformation in real time and simulated fault in each section, for example for section #1: $m_{1} = ||{\text{FFT}}(v_{a} \left( {t_{1} :t_{2} } \right)|_{\text{actual}} - |{\text{FFT}}(v_{a} \left( {t_{1} :t_{2} } \right)|_{{{\text{simulation}}_{{{\text{Section}}\left( 1 \right)}} }} |$

Appendix 2

See Table 15.

Table 15 Load information of each node in feeder which is shown in Fig. 6 [19]