Magnetic Flux Density Feature Analysis and CT Saturation Region Recognition and Reconstruction Technology

doi:10.11930/j.issn.1004-9649.202302075

Abstract

Abstract:

To solve the problem of relay protection caused by CT saturation, a CT saturation identification method is proposed based on flux density characteristics and secondary current reconstruction technology in the distortion area. The CT saturation is identified based on the characteristics of the magnetic flux density trapezoidal region at saturation. Then the saturation region of CT is obtained using the slope of the flux variance to construct the saturation criterion based on the difference between entry saturation and exit saturation and calculate the time corresponding to the start and end point of secondary current saturation. The protection starting criterion is constructed based on the current at the maximum grid load to avoid protection misoperation. Finally, the least square method is used to reconstruct the secondary current in the saturation region to reflect the primary current reliably. The simulation results based on PSCAD/EMTDC software show that the proposed method is accurate and reliable, and can quickly and effectively identify the saturated CT segment with a time error of less than 1 ms.

Key words: CT saturation, magnetic flux density, saturation compensation, current reconstruction, least square method

CLC Number:

TM77

Feng WANG, Jia ZHU, Shaolin JIAO, Yiquan LI, Hua XIE, Qingchun ZHAO. Magnetic Flux Density Feature Analysis and CT Saturation Region Recognition and Reconstruction Technology[J]. Electric Power, 2023, 56(10): 179-185, 193.

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URL: https://www.electricpower.com.cn/EN/10.11930/j.issn.1004-9649.202302075

https://www.electricpower.com.cn/EN/Y2023/V56/I10/179

Figures/Tables 13

References 27

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饱和次数	饱和开始时间/s		误差/s	饱和结束时间/s		误差/s
饱和次数	实际	检测	误差/s	实际	检测	误差/s
1	1.004	1.005	–0.001	1.013	1.013	0
2	1.018	1.018	0	1.022	1.021	0.001
3	1.025	1.026	–0.001	1.033	1.033	0
4	1.038	1.038	0	1.041	1.041	0

饱和次数	饱和开始时间/s		误差/s	饱和结束时间/s		误差/s
饱和次数	实际	检测	误差/s	实际	检测	误差/s
1	1.004	1.005	–0.001	1.013	1.013	0
2	1.018	1.018	0	1.022	1.021	0.001
3	1.025	1.026	–0.001	1.033	1.033	0
4	1.038	1.038	0	1.041	1.041	0

饱和次数	饱和开始时间/s		误差/s	饱和结束时间/s		误差/s
饱和次数	实际	检测	误差/s	实际	检测	误差/s
1	1.010	1.009	–0.001	1.015	1.015	0
2	1.025	1.026	–0.001	1.035	1.034	0.001

饱和次数	饱和开始时间/s		误差/s	饱和结束时间/s		误差/s
饱和次数	实际	检测	误差/s	实际	检测	误差/s
1	1.010	1.009	–0.001	1.015	1.015	0
2	1.025	1.026	–0.001	1.035	1.034	0.001

饱和次数	饱和开始时间/s		误差/s	饱和结束时间/s		误差/s
饱和次数	实际	检测	误差/s	实际	检测	误差/s
1	1.004	1.005	–0.001	1.013	1.013	0
2	1.018	1.018	0	1.022	1.021	0.001
3	1.025	1.026	–0.001	1.033	1.033	0
4	1.038	1.038	0	1.041	1.041	0