Steady-State Performance Analysis of an Integrated Wind Turbine Generating System in a DC Transmission System with Power Compensation System

Abstract

-An electric power compensation system for a DC transmission system with an integrated wind turbine generator is proposed. The proposed compensation system consists of a synchronous generator and a duplex reactor. This apparatus is connected to the sendingend circuit of the DC transmission system. A set of steady-state equations of the system is first derived. Then, the effect of the duplex reactor, which can eliminate the sending-end grid current distortion due to commutation of the converter, is explored. The relationships among power at the sending-end circuit are also revealed. It is shown that fluctuations in the sending-end grid power due to changes in wind velocities are compensated with the proposed system. Finally, the effects of the sending-end grid conditions on the steady-state characteristics of the system are studied.

Considerations of kVA capacity of power compensation systems for DC transmission system including wind turbine generating systems

“…Thereby, the steady-state equations of the system with the transformers expressed in the per-unit form are the same as the equations of the system without the transformers derived in [4], [5], and [8].…”

“…Then, the transformers shown in this figure are delta-star connected. In [4] and [5], a set of equations of the proposed system without the transformers has already been derived. Hence, let us now derive system equations, considering the effects of the transformers.…”

“…Notes -Xad_r, Xaq_r: d-axis and q-axis armature reaction reactances, Xdd0_r, Xdq0_r: d-axis and q-axis damper self-reactances, rf_s: field resistance of the synchronous compensator, Xs_r": subtransient reactance, R(= Rdc + 2 rac_s + 2rac_r): Rdc: DC reactor resistance, rac_s, rac_r: combined resistances of the AC reactor, the transformer, and the armature winding of the synchronous machines at the sending-end and receiving-end circuits respectively, Xγ_r: duplex reactor reactance, the parameters of considering magnetic saturation of the compensator (ka_r, σd_r, Xds0_r, k1_r, k2_r): refer to [2] and [5], Xl_r: armature leakage reactance, Cpmaxi: the maximum power coefficient of the ith (i = 1, 2, . .…”

“…The steady-state performances of the proposed DC transmission system have been analyzed through theoretical and experimental investigations [4], [5]. However, the kVA capacity of the system has been discussed little.…”

“…The power compensation system is connected to the sending-end grid through the transformer to compensate fluctuations in the sending-end grid power and receiving-end grid power due to changes in wind power [4], [5]. The synchronous compensator at the receiving-end power compensation system provides reactive power for the receiving-end grid and for commutation of the inverter thyristors.…”