Power Quality and Power Interruption Enhancement by Universal Power Quality Conditioning System with Storage Device



In this paper a novel design of Universal Power Quality Conditioning System (UPQS) is proposed which is composed of the DC/DC converter and the storage device connected to the DC link of UPQS for balancing the voltage interruption. The proposed UPQS can balance the reactive power, harmonic current, voltage sag and swell, voltage unbalance, and the voltage interruption. The performance of proposed system was analyzed through simulations with MATLAB\SIMULINK software. The proposed system can improve the power quality at the common connection point of the non-linear load and the sensitive load.


  1. Universal Power Quality Conditioning System (UPQS)
  2. Voltage interruption
  3. DC/DC converter
  4. Super-capacitor




Fig. 1: Configuration of proposed UPQC with energy storage.


                  Fig. 2: Nonlinear load current.

Fig. 3: Active and reactive power consumed by load.

    Fig. 4: Voltage sag compensation. (a) Source voltage. (b) Load voltage.


This paper proposes a new configuration of UPQC that consists of the DC/DC converter and the super capacitors for compensating the voltage interruption. The proposed UPQC can compensate the reactive power, harmonic current, voltage sag and swell, voltage unbalance, and the voltage interruption. The control strategy for the proposed UPQC was derived based on the Synchronous reference frame method. The operation of proposed system was verified through simulations with MATLAB/SIMULINK software. The proposed UPQC has the ultimate capability of improving the power quality at the installation point in the distribution system. The proposed system can replace the UPS, which is effective for the long duration of voltage interruption, because the long duration of voltage interruption is very rare in the present power system.


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Power Management Strategy for a Multi-Hybrid Fuel Cell/Energy Storage Power Generation Systems



This paper depicts a new configuration for modular hybrid power conversion systems, namely, multi-hybrid generation system (MHGS), and parallel connection at the output, such that the converter of each unit shares the load current equally. This is a significant step towards realizing a modular power conversion system architecture, where smaller units can be connected in any series/parallel grouping to realize any required unit specifications. The supercapacitor (SC) as a complementary source is used to compensate for the slow transient response of the fuel cell (FC) as a main power source. It assists the Fe to meet the grid power demand in order to achieve a better performance and dynamic behavior. Reliable control of the proposed MHGS with multiple units is also a challenging issue. In this paper, a simple control method to achieve active sharing of load current among MHGS modules is proposed. The simulation results verify the performance of the proposed structure and control scheme.


  1. Multi-hybrid generation system (MHGS)
  2. Fuel cell (FC)
  3. Dc/dc converter
  4. Supercapacitor (SC)
  5. Average load sharing (ALS)




Figure 1. Configuration of the FC/SC hybrid system.



Figure 2. Proposed control strategy of hybrid FC/SC power conversion



Figure 3. Dynamic response of MHGS, (a) load active power, (b) output power of hybrid units, (c) FC stack and SC module power of first hybrid umt, and (d) FC stack and SC module power of second hybrid unit.


Figure 4. Output waveform of (a) dc bus voltage, and (b) dc bus current.


Figure 5. Waveforms of unit’s (a) hydrogen input flow, (b) hydrogen partial pressure, and (d) oxygen partial pressure.


This paper proposes a comprehensive and effective multihybrid FC/SC power generation system structure and control strategy. The detailed model of the modular FC/SC hybrid system which includes an FC stack as a main power source and an SC as a complementary source is presented. In order to balance power sharing among the units, average load sharing technique is used. Elimination of outer voltage loop of ALS technique enhances reliability and reduces the complexity of the control structure. To show the superior dynamic behavior and power sharing of the proposed MHGS, results for two parallel hybrid systems are provided. The presented analysis and the simulation results offer a valuable structure with an effective control strategy to enhance power quality and management. These performances allow the integration MHGS into complex distributed generation systems such as microgrids.


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A Novel High StepUp DCDC Converter Based on Integrating Coupled Inductor and Switched-Capacitor Techniques for Renewable Energy Applications


In this paper, a novel high step-up dc/dc converter is presented for renewable energy applications. The suggested structure consists of a coupled inductor and two voltage multiplier cells, in order to obtain high step-up voltage gain. In addition, two capacitors are charged during the switch-off period, using the energy stored in the coupled inductor which increases the voltage transfer gain. The energy stored in the leakage inductance is recycled with the use of a passive clamp circuit. The voltage stress on the main power switch is also reduced in the proposed topology. Therefore, a main power switch with low resistance RDS(ON) can be used to reduce the conduction losses. The operation principle and the steady-state analyses are discussed thoroughly. To verify the performance of the presented converter, a 300-W laboratory prototype circuit is implemented. The results validate the theoretical analyses and the practicability of the presented high step-up converter.


Coupled inductor, DC/DC converters, High step-up, Switched capacitor.




Fig. 1. Circuit configuration of the presented high-step-up converter.


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Fig. 2. Simulation results under load 300 W.


This paper presents a new high-step-up dc/dc converter for renewable energy applications. The suggested converter is suitable for DG systems based on renewable energy sources, which require high-step-up voltage transfer gain. The energy stored in the leakage inductance is recycled to improve the performance of the presented converter. Furthermore, voltage stress on the main power switch is reduced. Therefore, a switch with a low on-state resistance can be chosen. The steady-state operation of the converter has been analyzed in detail. Also, the boundary condition has been obtained. Finally, a hardware prototype is implemented which converts the 40-V input voltage into 400-V output voltage. The results prove the feasibility of the presented converter.


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[4] J.H. Lee, T. J. Liang, and J. F. Chen, “Isolated coupled-inductor-integrated DC–DC converter with non-dissipative snubber for solar energy applications,” IEEE Trans. Ind. Electron., vol. 61, no. 7, pp. 3337–3348, Jul.2014.

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A High Gain Input-Parallel Output-Series DC/DC Converter with Dual Coupled Inductors


High voltage gain dc–dc converters are required in many industrial applications such as photovoltaic and fuel cell energy systems, high-intensity discharge lamp (HID), dc back-up energy systems, and electric vehicles. This paper presents a novel input-parallel output-series boost converter with dual coupled inductors and a voltage multiplier module. On the one hand, the primary windings of two coupled inductors are connected in parallel to share the input current and reduce the current ripple at the input. On the other hand, the proposed converter inherits the merits of interleaved series-connected output capacitors for high voltage gain, low output voltage ripple, and low switch voltage stress. Moreover, the secondary sides of two coupled inductors are connected in series to a regenerative capacitor by a diode for extending the voltage gain and balancing the primary-parallel currents. In addition, the active switches are turned on at zero current and the reverse recovery problem of diodes is alleviated by reasonable leakage inductances of the coupled inductors. Besides, the energy of leakage inductances can be recycled. A prototype circuit rated 500-W output power is implemented in the laboratory, and the experimental results shows satisfactory agreement with the theoretical analysis.


  1. DC–DC converter
  2. Dual coupled inductors
  3. High gain
  4. Input-parallel output-series.




Fig. 1. Equivalent circuit of the presented converter.


Fig.2 Key theoretical waveforms.



Fig.3 Key experimental current waveforms.


Fig.4 Voltage stress waveforms of power components.


For low input-voltage and high step up power conversion, this paper has successfully developed a high-voltage gain dc–dc converter by input-parallel output-series and inductor techniques. The key theoretical waveforms, steady-state operational principle, and the main circuit performance are discussed to explore the advantages of the proposed converter. Some important characteristics of the proposed converter are as follows: 1) it can achieve a much higher voltage gain and avoid operating at extreme duty cycle and numerous turn ratios; 2) the voltage stresses of the main switches are very low, which are one fourth of the output voltage under N = 1; 3) the input current can be automatically shared by each phase and low ripple currents are obtained at input; 4) the main switches can be turned ON at ZCS so that the main switching losses are reduced; and 5) the current falling rates of the diodes are controlled by the leakage inductance so that the diode reverse-recovery problem is alleviated. At the same time, there is a main disadvantage that the duty cycle of each switch shall be not less than 50% under the interleaved control with 180phase shift.


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