Transactions of China Electrotechnical Society  2024, Vol. 39 Issue (8): 2360-2370    DOI: 10.19595/j.cnki.1000-6753.tces.231576
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Active Injection DC Fault Location Method Based on Solid State Circuit Breaker
Wang Wei, Shuai Zhikang, Li Yang, He Lili, Fang Chenchen
College of Electrical and Information Engineering Hunan University Changsha 410082 China

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Abstract  Accurate and reliable fault location technology is crucial for DC fault repair and recovery with the rapid development and widespread application of DC distribution networks. The passive traveling wave ranging method has the issues of limited energy and insufficient traveling wave characteristic information. The traditional active traveling wave ranging method partially addresses these issues. However, the effects of line wave speed stability and sampling frequency are susceptible. This paper proposes an active injection DC fault location method based on a solid-state circuit breaker (SSCB). First, the SSCB is utilized to interrupt and actively inject signals with different pulse widths. The time difference between the first end of the injected pulse and the first end of the reflected wave is detected as the time interval of injection waveform propagation. This approach reduces errors caused by sampling frequency limitations. Then, the voltage line modulus of the cable line is extracted as the detection quantity, effectively weakening the coupling effect between the positive and negative lines and providing a stable wave speed measurement. Finally, based on the wavelet transform principle, an improved adaptive modulus maximum approach is proposed to detect the first and last moments of the pulse accurately. This approach also mitigates the impact of noise and transition resistance on ranging accuracy.
The simulation results show that the proposed method achieves high fault location accuracy for single-pole ground and bipolar short-circuit faults in a distribution network with a total line length of 10 km. The fault location accuracy is less than 0.55%. Even at a high sampling frequency of 80 kHz in 10 km DC distribution lines, the relative error of fault location remians within 1.14%, which reduces dependence on sampling frequency and enhances the robustness of the method. Moreover, the method exhibits resilience to noise interference at different signal-to-noise ratios. With signal-to-noise ratios of 40 dB, 20 dB, and 5 dB, the fault location accuracy with a relative error of less than 0.67% is consistently achieved. However, when the signal-to-noise ratio drops below 5 dB, the impact of noise on ranging and positioning increases, posing challenges for achieving high-precision fault location.
The following conclusions can be drawn from the simulation analysis. (1) The proposed method achieves high-precision fault location under single-pole ground or inter-pole short-circuit faults in DC distribution networks. It does not require additional equipment and is simple to operate. (2) A detection method is introduced to measure the average time difference between the end of the transmitted pulse wave and the end of the reflected wave of pulses with different widths. This method reduces the dependence on sampling accuracy caused by the traveling wave ranging method. (3) An improved adaptive modulus maximum method is proposed based on the principle of wavelet transform. The method adaptively sets the threshold value for modulus maximum selection based on fault line parameters, enhancing the resistance to transition resistance and noise in the distance measurement method. (4) The proposed single-ended ranging method does not need communication, which is suitable for applications without communication functions. However, it has the limitation of a dead zone in near-end ranges. Future research will focus on addressing this issue.
Key wordsDC distribution network      fault location      solid-state circuit breaker      active injection      adaptive modulus maximum     
Received: 23 September 2023     
PACS: TM614  
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Wang Wei
Shuai Zhikang
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He Lili
Fang Chenchen
Cite this article:   
Wang Wei,Shuai Zhikang,Li Yang等. Active Injection DC Fault Location Method Based on Solid State Circuit Breaker[J]. Transactions of China Electrotechnical Society, 2024, 39(8): 2360-2370.
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