# Novel Protection Scheme considering Tie Switch Operation in an Open-Loop Distribution System using Wavelet Transform

## Abstract

**:**

## 1. Introduction

- The possibility of mal-operation of the protective relay after closing of the tie switch in the open loop distribution system is analyzed.
- To prevent this mal-operation, a new index to classify the normal load current supply and the fault current injection using the WT is proposed.
- A novel protection scheme using the new index is proposed.

## 2. Wavelet Transform

_{1}+ D

_{2}+ … + D

_{n}+ A

_{n}

## 3. Mal-Operation Possibility of Protection Relay according to the Tie Switch Operation in the Open-Loop Distribution System

## 4. Novel Protection Scheme using Wavelet Transform in the Open-Loop Distribution System

#### 4.1. Characteristics of the Normal Load Current Supply and Fault Current Injection according to the Operation of the Tie Switch in the Open-Loop Distribution System

#### 4.2. New Index to Classify the Normal Load Current Supply and Fault Current Injection Using Wavelet Transform

#### 4.3. Selection of Mother Wavelet

^{2}, WO 32 mm

^{2}, and ACSR 60 mm

^{2}, respectively. The fault occurred in 50% of Line i1. The fault resistance was 1 Ω, and the fault type was a 3 phase-to-ground fault. After the system modeling using EMTP, the current waveform extracted 120 samples per cycle and the WT was performed using MATLAB (R2015a, Mathworks, Natick, MA, USA). We compared haar, db4, sym5, bior 3.1, and coif4, which are the most commonly used in power system signal analysis, to select the MW.

#### 4.4. Protection Scheme using Wavelet Transform in an Open Loop Distribution System

- No additional communication facilities are required among fault lines, tie switches, and healthy distribution lines.
- The nature functions of the OCR are also included, so that it can be operated correctly regardless of the fault locations.

## 5. Simulations

#### 5.1. System Model

#### 5.2. Simulation Conditions

#### 5.3. Simulation Results and Discussion

## 6. Conclusions

## Funding

## Conflicts of Interest

## References

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**Figure 1.**Filter bank representation of the discrete wavelet transform. LPF: Low Pass Filter; HPF: High Pass Filter.

**Figure 4.**Current flow after the closing of the tie switch when the fault section is successfully disconnected.

**Figure 5.**Current flow after the closing of the tie switch when the fault section is unsuccessfully disconnected.

**Figure 9.**Current waveform measured at CBj2. (

**a**) Current waveform at no fault condition; (

**b**) Current waveform at fault condition.

**Figure 15.**Flow chart of protection scheme using wavelet transform in open loop distribution system. RMS: root mean square.

**Figure 17.**Simulation results of case 1 and 2. (

**a**) Calculation result of classification value; (

**b**) Trip signal; (

**c**) Current flowing in the Y line in case 1; (

**d**) Current flowing in the Y line in case 2.

**Figure 18.**Simulation results of case 3 and 4. (

**a**) Calculation result of classification value; (

**b**) Trip signal; (

**c**) Current flowing in the Y line in case 3; (

**d**) Current flowing in the Y line in case 4.

**Figure 19.**Simulation results of case 5 and 6. (

**a**) Calculation result of classification value; (

**b**) Trip signal; (

**c**) Current flowing in the Y line in case 5; (

**d**) Current flowing in the Y line in case 6.

**Figure 20.**Simulation results of case 7 and 8. (

**a**) Calculation result of classification value; (

**b**) Trip signal; (

**c**) Current flowing in the Y line in case 7; (

**d**) Current flowing in the Y line in case 8.

MW | Maximum Value | Time Required to Reach the Maximum Value | |||
---|---|---|---|---|---|

Fault | No Fault | Difference | Fault (s) | No Fault (s) | |

Haar | 15220 | 3190 | 12030 | 0.2165 | 0.0165 |

Db4 | 392.5 | 57.2 | 335.3 | 0.2134 | 0.0134 |

Sym5 | 574.9 | 121.3 | 453.6 | 0.2132 | 0.0132 |

Bior3.1 | 953.3 | 122 | 831.3 | 0.2145 | 0.0145 |

Coif4 | 694.3 | 109.4 | 584.9 | 0.2095 | 0.0095 |

Case | Tie Switch Position | Fault Location at X Distribution Line | Fault Section Separation |
---|---|---|---|

Case 1 | Tie switch (1) | 102 section | Success |

Case 2 | Tie switch (1) | 102 section | Failure |

Case 3 | Tie switch (1) | 105 section | Success |

Case 4 | Tie switch (1) | 105 section | Failure |

Case 5 | Tie switch (2) | 102 section | Success |

Case 6 | Tie switch (2) | 102 section | Failure |

Case 7 | Tie switch (2) | 107 section | Success |

Case 8 | Tie switch (2) | 107 section | Failure |

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## Share and Cite

**MDPI and ACS Style**

Seo, H.-C.
Novel Protection Scheme considering Tie Switch Operation in an Open-Loop Distribution System using Wavelet Transform. *Energies* **2019**, *12*, 1725.
https://doi.org/10.3390/en12091725

**AMA Style**

Seo H-C.
Novel Protection Scheme considering Tie Switch Operation in an Open-Loop Distribution System using Wavelet Transform. *Energies*. 2019; 12(9):1725.
https://doi.org/10.3390/en12091725

**Chicago/Turabian Style**

Seo, Hun-Chul.
2019. "Novel Protection Scheme considering Tie Switch Operation in an Open-Loop Distribution System using Wavelet Transform" *Energies* 12, no. 9: 1725.
https://doi.org/10.3390/en12091725