Boosting voltage without electrochemical degradation using energy-harvesting circuits and power management system-coupled multiple microbial fuel cells

Kim, Taeyoung,Yeo, Jeongjin,Yang, Yoonseok,Kang, Sukwon,Paek, Yee,Kwon, Jin Kyung,Jang, Jae Kyung Elsevier 2019 Journal of Power Sources Vol.410 No.-

<P><B>Abstract</B></P> <P>Microbial fuel cells exhibit low output voltages, which must be enhanced for application in practical electronic devices. However, connecting microbial fuel cells in series for voltage boosting may cause voltage reversal, resulting in energy loss and biofilm damage. In this paper, different configurations for connecting microbial fuel cells and power-management systems are investigated to boost the voltage without reversal. The best configuration of the investigated method is as follows: A single power-management system is connected to a single microbial fuel cell or parallel-connected microbial fuel cells (boosted voltage from <0.2 V to 3.3 V); several such individual power-management systems are then connected in series (increased to 6.6 V using two power-management systems). Interestingly, when the single microbial fuel cell supplies insufficient power (<I>e.g.</I>, activity loss such as fuel starvation) to the power-management system in series, the voltage reversal of a capacitor occurs in the series-connected power-management system, and not in the microbial fuel cell. However, the effects of this voltage reversal are outweighed by the benefits of protecting the microbial fuel cell from failure. This approach can be informative for applications of power-management systems and microbial fuel cells as a power source in practical electronic devices.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Energy is harvested from swine wastewater using MFCs linked with PMSs. </LI> <LI> Parallel connection prevents voltage reversal and reduces energy loss. </LI> <LI> PMS linked to an MFC or MFCs in parallel prevent voltage reversal of MFCs. </LI> <LI> Activity loss of MFC causes voltage reversal of the capacitor of stacked PMSs. </LI> <LI> Kinetic imbalance of MFCs and capacitors cause voltage reversal. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

전력계통의 전압안정도향상을 위한 감시제어시스템 개발

이현철(Hyun-Chul Lee),정기석(Ki-Suk Jeoung),박지호(Ji-Ho Park),백영식(Young-Sik Baek) 대한전기학회 2013 전기학회논문지 Vol.62 No.4

This paper was developed a monitoring and control system to use reactive power control algorithm. This algorithm could be improved voltage stability in power system. This method was controlled the voltage for stability improvement, effective usage of reactive power, and the increase of the power quality. PMS(Power Management System) has been calculate voltage sensitivity, and control reactive power compensation device. The voltage control was used to the FACTS, MSC/MSR(Mechanically Switched Capacitors/Reactors), and tap of transformer in power system. The reactive power devices in power system were control by voltage sensitivity ranking of each bus. Also, to secure momentary reactive power, it had been controlled as the rest of reactive power in the each bus. In here, reactive power has been MSC/MSR. The simulation result, First control was voltage control as fast response control of FACTS. Second control was voltage control through the necessary reactive power calculation as slow response control of MSR/MSR. Third control was secured momentary reactive reserve power. This control was method by cooperative control between FACTS and MSR/MSC. Therefore, the proposed algorithm was had been secured the suitable reactive reserve power in power system.

Hybrid Control System for Managing Voltage and Reactive Power in the JEJU Power System

Sangsoo Seo,Yun-Hyuk Choi,Sang-Gyun Kang,Byongjun Lee,Jeong-Hoon Shin,Tae-Kyun Kim 대한전기학회 2009 Journal of Electrical Engineering & Technology Vol.4 No.4

This paper proposes a hybrid voltage controller based on a hierarchical control structure for implementation in the Jeju power system. The hybrid voltage controller utilizes the coordination of various reactive power devices such as generators, switched shunt devices and LTC to regulate the pilot voltage of an area or zone. The reactive power source can be classified into two groups based on action characteristics, namely continuous and discrete. The controller, which regulates the pilot bus voltage, reflects these characteristics in the coordination of the two types of reactive power source. However, the continuous type source like generators is a more important source than the discrete type for an emergency state such as a voltage collapse, thereby requiring a more reactive power reserve of the continuous type to be utilized in the coordination in order to regulate the pilot bus voltage. Results show that the hybrid controller, when compared to conventional methods, has a considerable improvement in performance when adopted to control the pilot bus voltage of the Jeju island system.

Reactive Power-Voltage Integrated Control Method Based on MCR

Dan Chen,Xiaosheng Huang,Guangsheng Li,Yi Wei,Wenjun Zeng,Chuihua Tian,Huan Shi,Hua Ye 제어로봇시스템학회 2010 제어로봇시스템학회 국제학술대회 논문집 Vol.2010 No.10

In power system, the voltage pulsation and deficiency or surplus of reactive power will have a great effect on the quality of electric power supply. Dynamicly local reactive power compensation is one of the best methods to reduce the power network loss and improve the efficiency of transmission and distribution.Through the effective methods of compensation, we can keep the balance of reactive power in the maximum degree by the maintenance of acceptable voltage. This paper firstly describes the principles of synthetic compensation of reactive power and voltage then analyzes the principle of magnetically controlled reactor-MCR in detail and derives the characteristics, secondly analyses the disadvantages of the conventional reactive power compensation devices and the advantages of MCR, thirdly on this basis designs a control strategy of reactive power and voltage which is based on MCR,so as to achieve the goal of dynamic reactive power compensation. At the end of paper, simulator and experimental research are carried out for the model of compensation method; the results accord with the theoretical analyses done before. So the compensation method is proved to be accurate in theory and feasible in practice.

A voltage deviation-memorizing reactive power controller for renewable energy sources

IPC Science and Technology Press 2019 International journal of electrical power energy s Vol.107 No.-

<P><B>Abstract</B></P> <P>The power output of renewable energy sources (RESs) is inherently unpredictable and frequently deviates from its forecasted value, leading to variations in voltage. These voltage deviations may significantly impede the exploitation of RESs in power systems. Moreover, these unpredictable deviations may also cause the operating point of the system to deviate from its optimal value. This paper proposes a reactive power control method for RESs that reduces voltage deviations resulting from fluctuations in output power, and may also reduce energy loss. To this end, a simple voltage deviation-memorizing technique is applied to the reactive power controller of the RES. By memorizing the voltage deviation, the proposed method rectifies the voltage deviations caused by output power fluctuations, while compensating for deviations caused by other factors via conventional volt/var control. The efficacy of this combination of control methods is verified using simulations.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A simple reactive power controller that can memorize the voltage deviation from the optimal operating point is proposed. </LI> <LI> Voltage deviations due to RESs’ own output power as well as other RESs’ power fluctuations are reduced. </LI> <LI> Deviations from the optimal operating point of the RESs are reduced. </LI> <LI> The proposed method outperformed the conventional method in terms of voltage deviation and line loss reduction. </LI> </UL> </P>

Active Power Tracking Control for DC‑Link Voltage Suppression of MVDC System with Voltage‑Sourced Converter

최상재,임성훈 대한전기학회 2020 Journal of Electrical Engineering & Technology Vol.15 No.1

The newly increased electrical energy is needed around the metropolitan area, and therefore, the transmission system is needed to be reorganized. MVDC (medium voltage direct current) system is an attractive one for constructing these new systems. This MVDC system, which is composed of two or more VSCs (voltage-sourced converters), prevents the degradation of system reliability due to renewable energy resource and is contributed to making it more stable for power supplying companies to supply the electrical power. Furthermore, to connect the increased renewable energy resource with larger capacity into the main grid through this MVDC system, the regulations such as FRT (fault ride through) for the grid have been more and more required. According to the FRT, the VSC system is required to supply the reactive current to grid when the grid voltage drops below the allowed voltage range. However, the FRT operation can cause the DC-link voltage in the MVDC system to increase. If the DC-link voltage exceeds the nominal voltage, the damage to the DC-related application may occur. In this paper, as the method to solve this problem, the application of the APTC (active power tracking control) into the MVDC system was proposed. The APTC is based on the principle that the DC-link voltage is determined by the power balance between the incoming and the outgoing active powers into the DC-link. If the outgoing active power decreases due to the short circuit in grid side, the DC-link voltage rises with the constant incoming active power. However, if the incoming active power is controlled to be reduced by the APTC performance of the MVDC system at the same time, the DC-link voltage is expected to be maintained at a constant level. The efectiveness of the suggested APTC application was verifed through the PSCAD (power system computer aided design)/EMTDC (electro magnetic transient design and control) simulation.

Improved Power Control of DFIGs Driven by Wind Turbine under Unbalanced Grid Voltage

Shehata E. G. 대한전기학회 2024 Journal of Electrical Engineering & Technology Vol.19 No.1

Undesired oscillation components appear in active and reactive powers, electromagnetic torque and DC-link voltage of doubly fed induction generators (DFIGs) connected to unbalanced grid voltage. These components oscillate at double source frequency as a result of negative sequence components in voltage and current. Diferent direct power control (DPC) techniques were studied in literatures to damp these oscillations. However, these techniques require sequence decomposition process, axes transformation of stator voltage/current and estimation of diferent power components which complicate the overall control system. This paper presents a simplifed DPC of DFIGs in stationary reference frame under normal and unbalanced grid voltage. Decomposition process, axes transformation and compensation power terms are totally eliminated. Vector proportional- integral (VPI) controllers are designed to regulate stator active and reactive powers. The performance of the proposed DPC scheme using VPI and proportional-integral-resonant (PIR) controllers is analyzed and compared under different operating conditions. Bode diagram of open loop and closed loop control using VPI and PIR are studied to illustrate stability, steady state and transient response of the two controllers. Also, the performance of proposed technique and previous DPCs designed in synchronous reference frame is compared to prove the validity of proposed one. The results show that proposed DPC using VPI has superior performance in steady state and transient conditions with simple implementation. Undesired oscillation components appear in active and reactive powers, electromagnetic torque and DC-link voltage of doubly fed induction generators (DFIGs) connected to unbalanced grid voltage. These components oscillate at double source frequency as a result of negative sequence components in voltage and current. Different direct power control (DPC) techniques were studied in literatures to damp these oscillations. However, these techniques require sequence decomposition process, axes transformation of stator voltage/current and estimation of different power components which complicate the overall control system. This paper presents a simplified DPC of DFIGs in stationary reference frame under normal and unbalanced grid voltage. Decomposition process, axes transformation and compensation power terms are totally eliminated. Vector proportional- integral (VPI) controllers are designed to regulate stator active and reactive powers. The performance of the proposed DPC scheme using VPI and proportional-integral-resonant (PIR) controllers is analyzed and compared under different operating conditions. Bode diagram of open loop and closed loop control using VPI and PIR are studied to illustrate stability, steady state and transient response of the two controllers. Also, the performance of proposed technique and previous DPCs designed in synchronous reference frame is compared to prove the validity of proposed one. The results show that proposed DPC using VPI has superior performance in steady state and transient conditions with simple implementation.

3-Phase 4-wire UPQC Topology with reduced DC-link Voltage rating for Power Quality Improvement using Fuzzy Controller

Kadali Jagadeesh,Dasari Prasad,Dr.P. Ramesh 보안공학연구지원센터 2016 International Journal of Signal Processing, Image Vol.9 No.1

Unified power quality conditioner is one of the advanced forms of power conditioning device, which is a combination of back to back connected series APF and shunt active power filter (SAPF) connected to a common DC link voltage. This topology will facilitates this device to have a reduced dc-link voltage without reducing its compensation capability. This device is mainly used in improving the power quality. For the improvement of power quality (PQ) complications in a 3-phase 4-wire distribution system, two topologies are presented. In this paper a four-leg voltage source inverter (VSI) based topology of a four-wire UPQC is discussed in this work. The performance of each topology of this device is evaluated for different PQ problems such as voltage harmonic mitigation, load balancing, source neutral current mitigation, current harmonic mitigation, and power-factor correction. The main purpose this device is to compensate load current and supply voltage imperfections. Converter and control analysis is presented together with the results showing the modes of operation. Detailed design aspect of the series capacitor and VSI parameters has been discussed in this paper. For better power quality improvement the PI controller is replaced by the fuzzy controller and the results are verified. The proposed topology enables UPQC to compensate current harmonics, voltage sags, and voltage swells with a reduced DC-link voltage without reducing its compensation capability by resolving the circuit in MATLAB/SIMULINK software.

Reactive Power Control Strategy for Inverter-based Distributed Generation System with a Programmable Limit of the Voltage Variation at PCC

Ji-Hoon Im,San Kang,Seung-Ho Song(송승호),Seung-Ki Jung,Ju-Yeop Choi,Ick Choy 전력전자학회 2011 ICPE(ISPE)논문집 Vol.2011 No.5

In a grid connected distributed generator, the voltage variation problem at the point of common coupling(PCC) is investigated. This is one of the most frequent power quality issues for the grid connection of large amount of the input power into a weak grid. Through a simplified modeling of the distributed generator and the power network, the magnitude of PCC voltage variation is calculated using the equivalent circuit parameters and the output power of the distributed generator. In addition, the required amount of reactive power which can compensate the voltage variation is presented analytically using a vector diagram method. With the proposed compensation method in a power conditioning system(PCS) for a distributed generation, the PCC voltage variation can be minimized automatically even though the power fluctuation occurs due to the change of input power. The proposed method of the calculation and compensation of the PCC voltage variation is verified by computer simulation and experimental results.

공정 코너별 LVCC 마진 특성을 이용한 전력 소모 개선 Voltage Binning 기법

이원준(Won Jun Lee),한태희(Tae Hee Han) 대한전자공학회 2014 전자공학회논문지 Vol.51 No.7