Investigation on Switching Patterns of Direct Power Control Strategies for Grid-Connected DC–AC Converters Based on Power Variation Rates

Abstract

This paper investigates the switching patterns of direct power control (DPC) strategies for three-phase grid-connected voltage-sourced dc-ac converters. The instantaneous variation rates of active and reactive powers by applying each converter voltage vector in 12 different sectors are deduced. In terms of hysteresis look-up-table DPC, based on the power variation rates, modified switching tables are presented to alleviate the active power pulsations, and an asymmetrical hysteresis controller is proposed for active power control to eliminate its steady-state errors. As to predictive DPC, according to the power variation rates, the cause is identified to that the values of the predicted duration times for the auxiliary active voltage vector become negative. Consequently, to solve this problem, two new alternative vector sequences are proposed and compared. A simple compensation method is further added to the basic control scheme of predictive DPC to deal with grid voltage unbalances. Experimental results on a 1.5-kVA gridconnected dc-ac converter are presented to validate the feasibility of the improved switching patterns and the unbalanced compensation method on the DPC strategies for dc-ac converters.

Digital Control Techniques Based on Voltage Source Inverters in Renewable Energy Applications: A Review

“…The major drawback of hysteresis controller is its uncontrolled switching frequency; however, researchers are working on improving this controller and several works are presented and several techniques are proposed in the literature. Main advances in this technique are direct torque control (DTC) [87,88,95,96] and direct power control (DPC) [97][98][99]. In DPC, active and reactive powers are directly controlled, however, in DTC torque and flux of the system are controlled.…”

Enhanced Predictive Current Control of Three-Phase Grid-Tied Reversible Converters with Improved Switching Patterns

“…This item should be taken into consideration when the algorithm is implemented. Recently, this has been paid special attention to, and several improved versions of this control methodology have been proposed [4,[28][29][30][31][32]. In [4], a generalized predictive direct power control strategy was proposed.…”

“…Nevertheless, even though steady-state performance deteriorations can be successfully suppressed, those transient performance deteriorations caused by the incorrect selection of voltage vectors were not paid attention to. Besides, transient performance deterioration caused by the negative duration times also was not mentioned or analysed in previous studies [30][31][32]. Besides, the research conducted in [31,32] only refers to the control actions when the converter is operating in the rectifier mode.…”

“…Besides, transient performance deterioration caused by the negative duration times also was not mentioned or analysed in previous studies [30][31][32]. Besides, the research conducted in [31,32] only refers to the control actions when the converter is operating in the rectifier mode. The corresponding control problem under the situation of reversible power flows was not properly solved.…”

Dynamic Modeling and Analysis of Single-Stage Boost Inverters under Normal and Abnormal Conditions

“…extensively used in literature for investigation of the dynamic performance of large power systems in the presence of the grid-connected inverters [59][60][61][62][63].…”