Now showing 1 - 3 of 3
  • Publication
    Neutral current reduction control for smart transformer under the imbalanced load in distribution system
    Imbalanced loads arouse neutral current looping in the distribution system, which increases power loss and results in neutral potential variation. Compared to the conventional power transformer, the smart transformer (ST) has advantages on the downstream voltage regulation. Thus, this paper proposes a voltage control strategy based on ST to reduce the LV grid neutral current according with EN 50160 imbalanced voltage standard. The proposed control has been validated in the Matlab/Simulink, and the system performance under the proposed control has been simulated under the imbalanced loading profile in a 400 kVA, 10 kV/400 V distribution network. The results prove the proposed control can practically reduce the neutral current.
    Scopus© Citations 7  380
  • Publication
    Neutral Current Optimization Control for Smart Transformer-fed Distribution System under Unbalanced Loads
    EU In a 3-phase 4-wire LV distribution system, unbalanced loads lead to neutral current (NC) looping resulting in increase of power losses and variation of neutral potential. Compared to the conventional power transformer, Smart Transformer (ST) has strict current limitations to avoid overcurrent. However, its advantages on the downstream LV grid voltage regulation can provides the capability to regulate excessive NC. This paper proposes a closed-loop NC optimization control in order to, on the one hand, minimize the NC current in the normal operation satisfying the standard EN 50160 requirement, on the other hand, suppress the NC current in extreme cases to avoid the overcurrent damage of the ST. The proposed control strategies are validated by experimental tests via the hardware-in-the-loop setup and a case study based on a 350kVA, 10kV/400V, ST-fed distribution network under unbalanced loading profile according to the 3-phase 4-wire distribution grid in Manchester area. The results clearly prove the effectiveness and flexibility of the proposed NC optimization control strategies on the NC suppression and minimization.
      372Scopus© Citations 14
  • Publication
    Smart Transformer and Low Frequency Transformer Comparison on Power Delivery Characteristics in the Power System
    Smart transformer is a power electronics-based transformer, offering voltage regulation and DC connectivity. As a transformer, its basic function is still power delivery. Smart transformer with advanced controls can support MV gird voltage by absorbing/injecting reactive power while actively regulate the LV grid voltage. Due to the controllable voltage in both MV and LV side, the power delivery of smart transformer is flexible. This paper focuses on the power delivery characteristic of smart transformer and compares with the conventional low frequency transformer with the help of STACTOM at its primary side or on load tap changer at its secondary side, in the power system by means of maximum deliverable power and power-voltage curve analysis. The Simulink results validate that the smart transformer improves system voltage stability compared to the traditional low frequency transformer with load tap changer.
      591Scopus© Citations 11