A Novel Control Method for D-STATCOM under Unbalanced Conditions

A novel control method for D-STATCOM under unbalanced condition is proposed in this paper. In the proposed method, the load and the compensator are taken as a whole comprehensive load, and the control object is that the line side only provides positive sequence active currents. The control scheme proposed is made up of DC voltage controller and current controller. The former mainly maintains the voltage of DC-capacitor at a desire value. The latter based on source currents detection, which has a close-loop structure, is presented in 'dq' reference frame. In the current controller, the reference of d-axis is provided by DC voltage controller and the reference current of q-axis is zero. So the control method proposed omits complicated load reactive current extraction which generates reference value for currents tracking controller in traditional control method based on load currents detection. It simplifies the control scheme. Compared to double 'dq' decoupled control method usually used for D-STATCOM under unbalanced conditions, the control scheme has a simpler structure, less calculation and is more convenient to realize. Simulation results show that D-STATCOM applying proposed control method can achieve good performance under unbalanced conditions.

[1]  F. L. Luo,et al.  Trinary hybrid multilevel inverter used in STATCOM with unbalanced voltages , 2005 .

[2]  B. Blazic,et al.  Improved D-StatCom control for operation with unbalanced currents and voltages , 2006, IEEE Transactions on Power Delivery.

[3]  M. B. Brennen,et al.  Vector analysis and control of advanced static VAr compensators , 1991 .

[4]  Farhat Fnaiech,et al.  Nonlinear control technique to enhance dynamic performance of a shunt active power filter , 2003 .

[5]  Paolo Mattavelli,et al.  An adaptive controller in stationary reference frame for D-statcom in unbalanced operation , 2004, IEEE Transactions on Industrial Electronics.

[6]  Liu Wenhua,et al.  Balancing compensation of unbalanced load based on single phase STATCOM , 2004, The 4th International Power Electronics and Motion Control Conference, 2004. IPEMC 2004..

[7]  Mariesa L. Crow,et al.  STATCOM control for power system voltage control applications , 2000 .

[8]  G. Joos,et al.  Dynamic performance of PWM STATCOMs operating under unbalance and fault conditions in distribution systems , 2001, 2001 IEEE Power Engineering Society Winter Meeting. Conference Proceedings (Cat. No.01CH37194).

[9]  Fang Zheng Peng,et al.  Dynamic performance and control of a static VAr generator using cascade multilevel inverters , 1996, IAS '96. Conference Record of the 1996 IEEE Industry Applications Conference Thirty-First IAS Annual Meeting.

[10]  Mauricio Aredes,et al.  Multi-pulse STATCOM operation under unbalanced voltages , 2002, 2002 IEEE Power Engineering Society Winter Meeting. Conference Proceedings (Cat. No.02CH37309).

[11]  C.O. Nwankpa,et al.  A new type of STATCOM based on cascading voltage source inverters with phase-shifted unipolar SPWM , 1998, Conference Record of 1998 IEEE Industry Applications Conference. Thirty-Third IAS Annual Meeting (Cat. No.98CH36242).

[12]  Kamal Al-Haddad,et al.  DSP-based indirect-current-controlled STATCOM. Part 1: Evaluation of current control techniques , 2000 .

[13]  Robert H. Lasseter,et al.  Statcom controls for operation with unbalanced voltages , 1998 .