Research on Hierarchical and Gradual Cooperative Voltage Regulation Strategy Based on OLTC and MDT

The voltage fluctuation on the low voltage side caused by the distributed generation (DG) in the new distribution network is the key factor affecting the power quality of users. this paper proposes a hierarchical and gradual cooperative voltage regulation control strategy based on on-load regulation transformer (OLTC) and modular distribution transformer (MDT) under the condition of sufficient reactive power. In this strategy, the concept of voltage cross section quality is first proposed and the model is given. Then the voltage fluctuation range is divided into three intervals: Interval 1 is the normal region, interval 2 is the slight over-limit region, and interval 3 is the serious over-limit region. Considering the economy and fast response of MDT, the strategy uses MDT as the main adjustment mode and OLTC as the backup adjustment means. Finally, the simulation not only verifies the feasibility of this strategy under normal conditions but also demonstrates its ability to prioritize the voltage quality of important loads during emergency situations.