Reactive Power Control Strategy Based on DC Capacitor Voltage Control for Active Load Balancer in Three-Phase Four-Wire Distribution Systems

Abstract

This paper proposes a reactive power control strategy for the active load balancer (ALB) in three-phase four-wire distribution systems. The proposed reactive power control strategy is based on constant DC capacitor voltage control only, which is always used in active power line conditioners. Therefore, the proposed approach does not require active and reactive calculation blocks of load currents for the reference source current calculation. The power factor of the source side currents can be adjusted under the balanced load condition using the proposed reactive power control strategy. The basic principle of the reactive power control strategy for the ALB is discussed in detail and verified via digital computer simulation using power electronic simulation (PSIM) software. A prototype experimental model is constructed and tested to demonstrate the validity and high practicability of the proposed control strategy. Simulation and experimental results indicate that balanced source currents with a predefined power factor are achieved when the proposed control strategy is applied to the three-phase four-wire distribution systems.

Design of the Current and the Voltage Observers for Active-Load-Balancer (ALB) in Model Predictive Control System

“…Besides, the control strategy based on active and reactive instantaneous power theory for regulating ALB current, presented in [14]. However, the traditional active and reactive power control theory suffers from a significant number of computation steps and computational burden.…”

“…Clearly, from (14) to predict the ALB output current, if, the inverter voltage, load current, and PCC voltage are required. The inverter voltage can be calculated by (6).…”

“…By using the estimated voltage of PCC vest,c(k), measured value of filter current if(k) and the estimated load current iest,o(k), for all 16 possible switching states the output current of ALB converter for the next sampling step if(k+1) is predicted. Based on (14), to predict the ALB output current, the load current io(k) and PCC voltage vc(k) are obligatory. To improve reliability, costs, and quality of compensation, in the proposed algorithm the estimated values of voltage and current are used instead of the measured values.…”

“…However, the unpredictable behavior of photovoltaic generation and the high complexity of the control system, are the main problems of this smart technique. Consequently, the DC link voltage regulating incorporates with a simple control technique for active load balancer (ALB) has been proposed in [14]. However, the use of the classic proportional-integral (PI) control system and delays are affected the performance of the ALB converter.…”

DC-Link Voltage Balance Control in Three-phase Four-wire Active Power Filters

“…Fortunately, some published studies have investigated the DC-link voltage control in three-phase four-wire APFs [7]- [20]. However, these existing studies mainly focus on minimum DC-link voltage designs [7]- [10], DC-link voltage control strategies [11]- [13], adaptive DC-link voltage references values [14]- [16], the control algorithms applied to the DC-link voltage controller [17]- [20], and the DC-link voltage control along with the improvements of the current control strategy [21], [22]. The balance between the DC-link upper and lower capacitor voltages, which is a unique problem in three-phase four-wire split-capacitor APFs, had still not been studies or analyzed.…”