DG control strategies for grid voltage unbalance compensation

With the high level penetration of power electronics interfaced Distributed Generation (DG) systems, applying these systems to compensate the grid voltage unbalance is becoming an important and interesting ancillary service for the utility. However, compensating the unbalance voltage leads to active power oscillation from the DG and may cause adverse effects of the DG operation. This paper proposes two DG control strategies for grid voltage unbalance compensation with reduced effects on the DG active power oscillation. In the first control strategy, the active power oscillation is fully cancelled at Point of Common Coupling (PCC). However, the level of unbalance compensation cannot be controlled directly in this method. Therefore, a second control strategy is proposed to minimize the active power oscillation (instead of completely cancel it) and with adjustable unbalance compensation level according to the DG available capacity. The validity of these two control strategies have been verified by case study results.

[1]  Mehdi Savaghebi,et al.  Secondary Control for Voltage Quality Enhancement in Microgrids , 2012, IEEE Transactions on Smart Grid.

[2]  Jinjun Liu,et al.  Strategies and Operating Point Optimization of STATCOM Control for Voltage Unbalance Mitigation in Three-Phase Three-Wire Systems , 2007, IEEE Transactions on Power Delivery.

[3]  Roger C. Dugan,et al.  Planning for distributed generation , 2001 .

[4]  Tzung-Lin Lee,et al.  A Cooperative Unbalance Compensation Method for Distributed Generation Interface Converters , 2007, 2007 IEEE Industry Applications Annual Meeting.

[5]  M. Liserre,et al.  Independent PQ Control for Distributed Power Generation Systems under Grid Faults , 2006, IECON 2006 - 32nd Annual Conference on IEEE Industrial Electronics.

[6]  Frede Blaabjerg,et al.  Current control method for distributed generation power generation plants under grid fault conditions , 2011, IECON 2011 - 37th Annual Conference of the IEEE Industrial Electronics Society.

[7]  Pedro Rodriguez,et al.  Voltage quality improvement of microgrids under islanding mode , 2010, 2010 IEEE Energy Conversion Congress and Exposition.

[8]  Frede Blaabjerg,et al.  Multiresonant Frequency-Locked Loop for Grid Synchronization of Power Converters Under Distorted Grid Conditions , 2011, IEEE Transactions on Industrial Electronics.

[9]  Fei Wang,et al.  Pliant Active and Reactive Power Control for Grid-Interactive Converters Under Unbalanced Voltage Dips , 2011, IEEE Transactions on Power Electronics.

[10]  Tzung-Lin Lee,et al.  D-STATCOM With Positive-Sequence Admittance and Negative-Sequence Conductance to Mitigate Voltage Fluctuations in High-Level Penetration of Distributed-Generation Systems , 2013, IEEE Transactions on Industrial Electronics.

[11]  F. Blaabjerg,et al.  Investigation and improvement of transient response of DVR at medium voltage level , 2006, Twenty-First Annual IEEE Applied Power Electronics Conference and Exposition, 2006. APEC '06..

[12]  Hirofumi Akagi,et al.  Instantaneous Reactive Power Compensators Comprising Switching Devices without Energy Storage Components , 1984, IEEE Transactions on Industry Applications.

[13]  Mehdi Savaghebi,et al.  Autonomous Voltage Unbalance Compensation in an Islanded Droop-Controlled Microgrid , 2013, IEEE Transactions on Industrial Electronics.

[14]  Tzung-Lin Lee,et al.  A Cooperative Imbalance Compensation Method for Distributed-Generation Interface Converters , 2007 .

[15]  Fei Wang,et al.  Negative-sequence admittance control scheme for distributed compensation of grid voltage unbalance , 2012, 2012 IEEE 13th Workshop on Control and Modeling for Power Electronics (COMPEL).

[16]  Ehab F. El-Saadany,et al.  A Control Scheme for PWM Voltage-Source Distributed-Generation Inverters for Fast Load-Voltage Regulation and Effective Mitigation of Unbalanced Voltage Disturbances , 2008, IEEE Transactions on Industrial Electronics.