MVDC 배전망에 의한 인근 AC 변압기 포화 현상에 대한 연구

초록

As DC power and DC loads are connected to the power system on a large scale, the existing AC distribution network has reached its limits, and Medium-Voltage DC (MVDC) is emerging as a promising next-generation distribution network alternative. In the Republic of Korea, an AC/DC hybrid distribution network is planned for operation in 2030, and operation methods to replace existing AC distribution networks with DC distribution networks are under discussion. When a metallic return is used in an MVDC distribution network, DC current may flow from neutral conductors to ground through a multi-point grounding system, and some of this DC current may then flow through the ground to the neutral point of nearby transformers. The DC current flowing into the transformer causes a DC bias in the transformer magnetic flux, saturating the transformer during one half-cycle and causing problems such as harmonic distortion, acoustic noise, and excessive heat generation. Since existing measures to prevent transformer saturation can adversely affect AC system protection performance, this paper proposes a method for optimizing the value of a series resistor that can minimize the impact on AC protection systems while preventing transformer saturation.

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