EPE Association: EPE 2014 - DS3f: Grids Smart Grids

EPE 2014 - DS3f: Grids Smart Grids
You are here: EPE Documents > 01 - EPE & EPE ECCE Conference Proceedings > EPE 2014 ECCE Europe - Conference > EPE 2014 - Topic 06: Grids and Smart Grids > EPE 2014 - DS3f: Grids Smart Grids

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   A Placement Method of Fuzzy based Unified Power Flow Controller to Enhance Voltage Stability Margin
By FADI ALBATSH, Shameem AHMAD, Saad MEKHILEF, Hazlie MOKHLIS [View]
[Download]

Abstract: This paper presents a placement method of fuzzy logic based unified power flow controller (UPFC) inpower system network by analyzing dynamic voltage stability. Voltage stability indices namely LQPand voltage collapse point indicators (VCPI) indices are used to determine the weakest line for UPFCby dynamic load variation. The controllers of the shunt and series converters of the UPFC aredeveloped using fuzzy logic (FL) and proportional integral (PI) controllers respectively to enhance thedynamic voltage stability of the power system network.The simulation has been conducted in powersystem computer-aided design (PSCAD) environment where IEEE-5 and IEEE-14 bus system havebeen chosen as test bench systems. The results obtained through simulations have ensured theeffectiveness of the proposed placement method since fuzzy based UPFCs placement in the obtainedlocations resulted in significant improvment in voltage stability.

   Coordination control of Lithium battery-Supercapacitor hybrid energy storage system in a microgrid under unbalanced load condition
By Zhu YIXIN, Liu BAOQUAN, Zhuo FANG [View]
[Download]

Abstract: For a microgrid, it is important to supply high quality powers to consumers. However, due to the unbalanced load condition, the power quality of a microgrid is always weak. Normally, by the control method of negative-sequence voltage, the microgrid voltage can be enhanced. However, the unbalanced current problem is still unsolved for those main converters. In this paper, according to the hybrid energy storage devices, a coordination control strategy is proposed to enhance the power quality for microgrid under unbalanced load condition. The hybrid energy storage system (HESS) is composed of a lithium battery power conversion system (li-pcs) and an ultra-capacitor power conversion system (uc-pcs). The HESS employs li-pcs as the main unit to regulate power and the sc-pcs as the auxiliary unit to absorb unbalanced power. In this way, the main voltage source device of the microgrid, li-pcs, keeps a reasonable operation all the time. In addition, the HESS can operate in three modes: PQ mode, VF mode and Droop mode. While using Droop mode, several HESSs can operate together just like the feature of the distributed generation (DG) units with droop control method. Finally, Matlab simulation and experiment results verify the validity of the proposed strategy.

   Effect of Network Configuration and Load Profile on Efficiency of LVDC Distribution Network
By Jenni REKOLA, Juha JOKIPII, Teuvo SUNTIO [View]
[Download]

Abstract: The low voltage direct current (LVDC) distribution network is a promising solution to be considered in future smart grids. For facilitating the design of cost effective LVDC distribution networks, the total losses of the network with different configurations are evaluated and compared. The possibility to connect the customer loads asymmetrically, when the bipolar DC network is used and the fact that the customer has single-phase loads, which lead to phase-asymmetrical loading of a three-phase converter, are taken into account. According to the results presented in this paper, the highest efficiency is achieved when the ungrounded LVDC distribution network is supplied by two series connected line converters. When the length of the bipolar network is 600 m at maximum, three-phase load converters should be connected to 750 V DC with a 400V/400V isolation transformer. Instead, while the length of the DC network is over 600 m, the maximum efficiency is achieved when the unipolar network configuration is used by connecting the load converters to 1500 V DC with a 800V/400V isolation transformer.

   ENERGY MANAGEMENT SYSTEM FOR LVDC ISLAND NETWORKS
By Arun NARAYANAN, Pasi PELTONIEMI, Tero KAIPIA, Jarmo PARTANEN [View]
[Download]

Abstract: An energy management system (EMS) has been proposed to control energy balance in LVDC island networks comprisingsolar panels and batteries. The EMS uses the master/slave method with communication infrastructure based on proposedfunctionalities and operation modes. Its performance was verified by simulations and experiments with practical networks.

   Modelling of Aggregated Operation of Power Modules in Low-Voltage DC-Grids
By Kirill RYKOV, Leopold OTT, Jorge DUARTE, Elena LOMONOVA [View]
[Download]

Abstract: The paper focuses on small-signal analysis of aggregated operation of the low-voltage DC-grids comprising various power and load modules. Complex impedances, which can be identified experimentally, represent the internal structure of power converters and may become a reason for voltage instabilities while being gathered together in the DC-grid using cables. The paper proposes ideas to analyze and forecast possible resonance issues of parallel operation of power modules in the test model of the 380V DC-grid and make recommendations in order to avoid them.

   PERFORMANCE COMPARISON OF PHASE LOOKED LOOP ALGORITHMS APPLIED TO MICRO-INVERTERS FOR DISTRIBUTED PHOTOVOLTAIC GENERATION
By Mario CACCIATO, Giuseppe SCARCELLA, Giacomo SCELBA, Luca FINOCCHIARO [View]
[Download]

Abstract: The paper deals with the experimental comparison of different phase locked loop (PLL) algorithms for single phase, grid tied, photovoltaic generation systems; in particular, this work analyzes the effects of abnormal grid conditions on the output current and power control loops of a 250W micro-inverter unit, highlighting pros and cons of each PLL algorithm. The effectiveness of such algorithms has been evaluated by means of experimental tests analyzing the micro inverter operations when the grid voltage is affected by sags, dips, frequency variations and harmonic distortion. Harmonics rejection and dynamic response of the control algorithm in these operating conditions has been highlighted. In addition the computational burden required by each algorithm has been evaluated.

   Reactive Power Control by use of Boost Critical Conduction Mode Power Factor Correction Converter for Suppressing Voltage Rise in Distribution Network
By Ken-ichi KONDO, Jumpei BABA [View]
[Download]

Abstract: The authors have proposed a reactive power control method by use of boost critical conduction mode (CRM) power factor correction (PFC) converters to suppress voltage rise in distribution networks.Using this method, PFC converters can control not only inductive reactive power but also capacitive reactive power.Therefore, this method is useful to control voltage.In this paper, a PFC converter and a controller which realizes the proposed method is made to verify the reactive power control ability.The theoretical ratio between reactive and active power is in good agreement with the experimental results.

EPE 2014 - DS3f: Grids Smart Grids
You are here: EPE Documents > 01 - EPE & EPE ECCE Conference Proceedings > EPE 2014 ECCE Europe - Conference > EPE 2014 - Topic 06: Grids and Smart Grids > EPE 2014 - DS3f: Grids Smart Grids
	[return to parent folder]

	A Placement Method of Fuzzy based Unified Power Flow Controller to Enhance Voltage Stability Margin By FADI ALBATSH, Shameem AHMAD, Saad MEKHILEF, Hazlie MOKHLIS	[View] [Download]
Abstract: This paper presents a placement method of fuzzy logic based unified power flow controller (UPFC) inpower system network by analyzing dynamic voltage stability. Voltage stability indices namely LQPand voltage collapse point indicators (VCPI) indices are used to determine the weakest line for UPFCby dynamic load variation. The controllers of the shunt and series converters of the UPFC aredeveloped using fuzzy logic (FL) and proportional integral (PI) controllers respectively to enhance thedynamic voltage stability of the power system network.The simulation has been conducted in powersystem computer-aided design (PSCAD) environment where IEEE-5 and IEEE-14 bus system havebeen chosen as test bench systems. The results obtained through simulations have ensured theeffectiveness of the proposed placement method since fuzzy based UPFCs placement in the obtainedlocations resulted in significant improvment in voltage stability.

	Coordination control of Lithium battery-Supercapacitor hybrid energy storage system in a microgrid under unbalanced load condition By Zhu YIXIN, Liu BAOQUAN, Zhuo FANG	[View] [Download]
Abstract: For a microgrid, it is important to supply high quality powers to consumers. However, due to the unbalanced load condition, the power quality of a microgrid is always weak. Normally, by the control method of negative-sequence voltage, the microgrid voltage can be enhanced. However, the unbalanced current problem is still unsolved for those main converters. In this paper, according to the hybrid energy storage devices, a coordination control strategy is proposed to enhance the power quality for microgrid under unbalanced load condition. The hybrid energy storage system (HESS) is composed of a lithium battery power conversion system (li-pcs) and an ultra-capacitor power conversion system (uc-pcs). The HESS employs li-pcs as the main unit to regulate power and the sc-pcs as the auxiliary unit to absorb unbalanced power. In this way, the main voltage source device of the microgrid, li-pcs, keeps a reasonable operation all the time. In addition, the HESS can operate in three modes: PQ mode, VF mode and Droop mode. While using Droop mode, several HESSs can operate together just like the feature of the distributed generation (DG) units with droop control method. Finally, Matlab simulation and experiment results verify the validity of the proposed strategy.

	Effect of Network Configuration and Load Profile on Efficiency of LVDC Distribution Network By Jenni REKOLA, Juha JOKIPII, Teuvo SUNTIO	[View] [Download]
Abstract: The low voltage direct current (LVDC) distribution network is a promising solution to be considered in future smart grids. For facilitating the design of cost effective LVDC distribution networks, the total losses of the network with different configurations are evaluated and compared. The possibility to connect the customer loads asymmetrically, when the bipolar DC network is used and the fact that the customer has single-phase loads, which lead to phase-asymmetrical loading of a three-phase converter, are taken into account. According to the results presented in this paper, the highest efficiency is achieved when the ungrounded LVDC distribution network is supplied by two series connected line converters. When the length of the bipolar network is 600 m at maximum, three-phase load converters should be connected to 750 V DC with a 400V/400V isolation transformer. Instead, while the length of the DC network is over 600 m, the maximum efficiency is achieved when the unipolar network configuration is used by connecting the load converters to 1500 V DC with a 800V/400V isolation transformer.

	ENERGY MANAGEMENT SYSTEM FOR LVDC ISLAND NETWORKS By Arun NARAYANAN, Pasi PELTONIEMI, Tero KAIPIA, Jarmo PARTANEN	[View] [Download]
Abstract: An energy management system (EMS) has been proposed to control energy balance in LVDC island networks comprisingsolar panels and batteries. The EMS uses the master/slave method with communication infrastructure based on proposedfunctionalities and operation modes. Its performance was verified by simulations and experiments with practical networks.

	Modelling of Aggregated Operation of Power Modules in Low-Voltage DC-Grids By Kirill RYKOV, Leopold OTT, Jorge DUARTE, Elena LOMONOVA	[View] [Download]
Abstract: The paper focuses on small-signal analysis of aggregated operation of the low-voltage DC-grids comprising various power and load modules. Complex impedances, which can be identified experimentally, represent the internal structure of power converters and may become a reason for voltage instabilities while being gathered together in the DC-grid using cables. The paper proposes ideas to analyze and forecast possible resonance issues of parallel operation of power modules in the test model of the 380V DC-grid and make recommendations in order to avoid them.

	PERFORMANCE COMPARISON OF PHASE LOOKED LOOP ALGORITHMS APPLIED TO MICRO-INVERTERS FOR DISTRIBUTED PHOTOVOLTAIC GENERATION By Mario CACCIATO, Giuseppe SCARCELLA, Giacomo SCELBA, Luca FINOCCHIARO	[View] [Download]
Abstract: The paper deals with the experimental comparison of different phase locked loop (PLL) algorithms for single phase, grid tied, photovoltaic generation systems; in particular, this work analyzes the effects of abnormal grid conditions on the output current and power control loops of a 250W micro-inverter unit, highlighting pros and cons of each PLL algorithm. The effectiveness of such algorithms has been evaluated by means of experimental tests analyzing the micro inverter operations when the grid voltage is affected by sags, dips, frequency variations and harmonic distortion. Harmonics rejection and dynamic response of the control algorithm in these operating conditions has been highlighted. In addition the computational burden required by each algorithm has been evaluated.

	Reactive Power Control by use of Boost Critical Conduction Mode Power Factor Correction Converter for Suppressing Voltage Rise in Distribution Network By Ken-ichi KONDO, Jumpei BABA	[View] [Download]
Abstract: The authors have proposed a reactive power control method by use of boost critical conduction mode (CRM) power factor correction (PFC) converters to suppress voltage rise in distribution networks.Using this method, PFC converters can control not only inductive reactive power but also capacitive reactive power.Therefore, this method is useful to control voltage.In this paper, a PFC converter and a controller which realizes the proposed method is made to verify the reactive power control ability.The theoretical ratio between reactive and active power is in good agreement with the experimental results.