EPE Association: EPE 2019 - DS3h: Micro-Grids

EPE 2019 - DS3h: Micro-Grids
You are here: EPE Documents > 01 - EPE & EPE ECCE Conference Proceedings > EPE 2019 ECCE Europe - Conference > EPE 2019 - Topic 06: Grids, Smart Grids, AC & DC > EPE 2019 - DS3h: Micro-Grids

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   A Model Predictive Approach for Energy Management in Smart Buildings
By Tommaso CALDOGNETTO [View]
[Download]

Abstract: Effective and efficient energy management is crucial in smart electrical systems like nanogrids. The ap- plication of model predictive control (MPC) for the energy management of electrical energy storage in nanogrids for smart buildings is considered in this paper. An MPC strategy is devised in order to improve the nanogrid operation at the points of connection with the utility grid, integrating in the control infor- mation about future power generation and load consumption. The strategy is compared with a heuristic approach that exploits the energy storage only on an instantaneous basis, without any future predictions. It is shown that the MPC approach can provide convenient references to the power converters interfacing energy resources with the grid and significant long-term advantages as compared to the heuristic strategy.

   A Novel Distributed Secondary Control Strategy Applied to Hybrid AC/DC Microgrids
By Enrique ESPINA [View]
[Download]

Abstract: In this paper, a distributed secondary control strategy for hybrid ac/dc-microgrids is proposed. The control strategy restores the variables modified by the primary control loop, i.e. voltage on the dc-side and voltage amplitude and frequency of the ac-side, to their nominal values while maintaining a good power-sharing capability between ac- and dc-units. A distributed communication network among the generation units is needed for the proper performance of the control strategy, however, a high bandwidth communication network is not needed to ensure a good behaviour of the proposed control scheme. The effectiveness of the control scheme is validated through simulation of a 9.0kW hybrid ac/dc-microgrid.

   Accurate Reactive Power Sharing in Renewable-Prioritized Islanded Microgrids
By Jiahui JIANG [View]
[Download]

Abstract: An accurate reactive power sharing scheme aiming to prioritize renewable sources is proposed and implemented under modified droop control in islanded microgrids. In order to improve reactive powersharing accuracy, an interfacing inductor and grid voltage estimation strategy is used. Simulation andexperimental results show the efficacy of the approach.

   Analysis of the DPWM technique applied to a grid-connected 3L-NPC Inverter. FACTS Technologies and Power Quality in smart Grid.
By Jesús Sergio ARTAL-SEVIL [View]
[Download]

Abstract: This paper presents a Discontinuous Pulse With Modulation (DPWM) modulation technique applied to a grid-connected three-level neutral point-clamped (3L-NPC) converter. The document proposes a methodology for the control of the active and reactive power flows in a microgrid. The control algorithm of the grid-connected system is applied for voltage control. This control technique provides independent control active and reactive power flow into the utility grid while maintain the dc-link voltage constant. As a novelty it is implements a discontinuous PWM technique in the control of the grid-connected converter. In this way the losses in the converter are reduced while the efficiency of the equipment is increased. In recent years smart grids are key components in energy distribution. Power quality and reactive compensation are essential for the correct integration of renewable energies in small microgrids. This paper presents a comparison between the conduction and switching losses in semiconductor devices depending on the modulation technique (SPWM or DPWM) used. The power losses associated with the semiconductors that constitute the 3L-NPC topology have been compared. Active and reactive power control strategies are coordinated to improve the power quality and reliability of the system in microgrids. Other purpose is to improve the voltage unbalance and harmonic compensation in stand-alone grids. The simulation of the system was developed by the Matlab/Simulink.

   Application of a MILP-based Algorithm for Power Flow Optimisation within More-Electric Aircraft Electrical Power Systems
By Xin WANG [View]
[Download]

Abstract: This paper presents in detail how Mixed-Integer Linear Programming (MILP) can be used to solve the optimal power flow problem of Electrical Power Systems (EPSs) within More-Electric Aircraft (MEA). Continuous linear functions, integer variables and piecewise-linear functions are modelled to deal with bidirectional power flow, EPS control logic decisions, as well as non-linearity caused by efficiency curves.

   COOPERATIVE SECONDARY VOLTAGE CONTROL OF STATIC CONVERTERS IN A MICROGRID USING MODEL-FREE REINFORCEMENT LEARNING
By Edward SMITH [View]
[Download]

Abstract: Agent-based secondary voltage regulation in an islanded MicroGrid is complicated by non-linear system dynamics, state couplings and uncertain communication network topology information. This paper proposes an off-policy learning algorithm for cooperative secondary voltage control which can synthesize an optimal feedback controller in real-time without knowledge of the system model. A simulation model has been developed using MATLAB/Simulink, which demonstrates a working controller. Results from the simulations are included, and practical considerations regarding implementation on a real system discussed.

   Estimation-based Consensus Approach for Decentralized Frequency Control of AC Microgrids
By Yousef KHAYAT [View]
[Download]

Abstract: In this paper, a decentralized frequency control of ac microgrid (MG) governed by P-_ droop characteristics is presented. This approach is realized by applying an active power estimation to eliminate the required communication infrastructure in the secondary control layer. The proposed decentralized frequency control is achieved by employing the unique feature of the frequency as a global variable in autonomous ac MGs. By utilizing a consensus protocol, the proposed method restores the MG frequency to the nominal value while maintaining accurate power sharing of the droop mechanism. The consensus protocol is an estimation-based approach and does not require communication infrastructure. Experimental results verified accurate power-sharing and the frequency restoration to the nominal value without any communication requirement.

   Fault Detection in DC Microgrid using Teager Energy Operation on Wavelet-coefficients
By Miao LI [View]
[Download]

Abstract: Reliable operation of DC Microgrid (MG) in real time demands for efficient protection system design which solely depends on fault detection at the incipient stage. This paper proposes a fault detection algorithm which combines the features of both DWT and Teager energy operator to detect short circuit fault in DC MG. Firstly, the instantaneous fault current is decomposed in the frequency domain using sliding window based discrete wavelet transform. The mother wavelet for the decomposition is properly chosen by comparing different existing wavelets. Secondly, the teager energy of the rate of change of the coefficients derived from wavelet synthesis is calculated and considered as the potential parameter to detect and distinguish between the arcing as well as bus faults in a DC MG. The simulation model is developed using MATLAB/SIMULINK to report the results.

   Model Predictive Energy Management for Sustainable Off-Shore Oil and Gas Platforms
By Luca BIGARELLI [View]
[Download]

Abstract: This paper proposes a Two-Level Hierarchical Model Predictive Energy Management method (MPEM) for off-shore oil platforms with renewables. An economic cost function is at the basis of the High-Level controller, while a tracking cost function is designed for the Low-Level control layer. The power sources, the load and possible variation of the wind profile have been properly modeled. The control structure has been validated through simulations carried out in the MATLAB environment. Results are presented for different scenarios, which prove the robustness and effectiveness of the proposed control strategy.

   Model Validation of Power Electronics-based Networked Micro-grids by Prony Analysis
By Mobin NADERI [View]
[Download]

Abstract: In this paper, a complete small signal model of two networked microgrids (NMGs) is provided, whichcan be used in the stability analysis, stability margin derivation and controller design. This model isvalidated by comparing it with the simulated NMGs using the Prony analysis. In this method, the modes, calculated by eigenvalue analysis and contributing to a particular state variable, are identified using the participation matrix and compared with the natural frequencies of its waveform. The state variable waveform is locally measured from the simulated NMGs in the SimPowerSystems environment of MATLAB and its natural frequencies are calculated using Prony analysis. It is concluded that Pronyanalysis estimates the natural frequencies well and there is a good similarity between them and thecalculated modes, which shows the modeling validation.

   Modeling and Real-Time Simulation of a DC Shipboard Microgrid
By Federico SILVESTRO [View]
[Download]

Abstract: This paper illustrates the modelling of a Low Voltage DC ship electrical system, including batteries and variable speed generators, and its implementation on the Opal-RT real-time simulator. There is more and more necessity to represent the full dynamics of the component and relative control to have a proper knowledge of the behavior of the system. The use of digital twin is becoming more and more attractive in order to have a complete and reliable tool to assess the system behavior in all conditions. The coupling of variable speed generator and BESS (Battery Energy Storage Systems) is an efficient solution in order to improve energy efficiency on board of marine vessel and it is necessary in different SECA areas that have strong environmental requirements. Results show the effectiveness of the proposed simulation platform and the results obtained by the implementation of a droop-based power control strategy.

   V-dP/dI droop control technique with d²P/dI² to improve steady state performance for multiple PV modules in a dc microgrid
By Wing Chun CHAN [View]
[Download]

Abstract: DC microgrids have been widely used in distributed generation networks due to intermittent nature of renewables, low conversion losses, common interface with dc renewable sources and high reliability. In order to regulate the dc bus voltage and achieve proportional power sharing, the conventional V-dP/dV droop control strategy is performed by calculating the slope of tangent of P-V characteristic. However, the main challenges of this control scheme are poor dynamic behaviour and low quality of PV power. This paper presents a decentralized coordinated PV droop control method, which applies dP/dI for accurate energy distribution and faster response speed. Moreover, the inner control parameter d2P/dI2 is used to further minimize the PV power fluctuation in a steady state which allows to track the error with a corrective action. The proposed control strategy seamlessly transfers the MPPT algorithm to voltage regulation mode in a fully decentralized approach. Simulation study is conducted to demonstrate how the transient and dynamic responses have been significantly improved.

EPE 2019 - DS3h: Micro-Grids
You are here: EPE Documents > 01 - EPE & EPE ECCE Conference Proceedings > EPE 2019 ECCE Europe - Conference > EPE 2019 - Topic 06: Grids, Smart Grids, AC & DC > EPE 2019 - DS3h: Micro-Grids
	[return to parent folder]

	A Model Predictive Approach for Energy Management in Smart Buildings By Tommaso CALDOGNETTO	[View] [Download]
Abstract: Effective and efficient energy management is crucial in smart electrical systems like nanogrids. The ap- plication of model predictive control (MPC) for the energy management of electrical energy storage in nanogrids for smart buildings is considered in this paper. An MPC strategy is devised in order to improve the nanogrid operation at the points of connection with the utility grid, integrating in the control infor- mation about future power generation and load consumption. The strategy is compared with a heuristic approach that exploits the energy storage only on an instantaneous basis, without any future predictions. It is shown that the MPC approach can provide convenient references to the power converters interfacing energy resources with the grid and significant long-term advantages as compared to the heuristic strategy.

	A Novel Distributed Secondary Control Strategy Applied to Hybrid AC/DC Microgrids By Enrique ESPINA	[View] [Download]
Abstract: In this paper, a distributed secondary control strategy for hybrid ac/dc-microgrids is proposed. The control strategy restores the variables modified by the primary control loop, i.e. voltage on the dc-side and voltage amplitude and frequency of the ac-side, to their nominal values while maintaining a good power-sharing capability between ac- and dc-units. A distributed communication network among the generation units is needed for the proper performance of the control strategy, however, a high bandwidth communication network is not needed to ensure a good behaviour of the proposed control scheme. The effectiveness of the control scheme is validated through simulation of a 9.0kW hybrid ac/dc-microgrid.

	Accurate Reactive Power Sharing in Renewable-Prioritized Islanded Microgrids By Jiahui JIANG	[View] [Download]
Abstract: An accurate reactive power sharing scheme aiming to prioritize renewable sources is proposed and implemented under modified droop control in islanded microgrids. In order to improve reactive powersharing accuracy, an interfacing inductor and grid voltage estimation strategy is used. Simulation andexperimental results show the efficacy of the approach.

	Analysis of the DPWM technique applied to a grid-connected 3L-NPC Inverter. FACTS Technologies and Power Quality in smart Grid. By Jesús Sergio ARTAL-SEVIL	[View] [Download]
Abstract: This paper presents a Discontinuous Pulse With Modulation (DPWM) modulation technique applied to a grid-connected three-level neutral point-clamped (3L-NPC) converter. The document proposes a methodology for the control of the active and reactive power flows in a microgrid. The control algorithm of the grid-connected system is applied for voltage control. This control technique provides independent control active and reactive power flow into the utility grid while maintain the dc-link voltage constant. As a novelty it is implements a discontinuous PWM technique in the control of the grid-connected converter. In this way the losses in the converter are reduced while the efficiency of the equipment is increased. In recent years smart grids are key components in energy distribution. Power quality and reactive compensation are essential for the correct integration of renewable energies in small microgrids. This paper presents a comparison between the conduction and switching losses in semiconductor devices depending on the modulation technique (SPWM or DPWM) used. The power losses associated with the semiconductors that constitute the 3L-NPC topology have been compared. Active and reactive power control strategies are coordinated to improve the power quality and reliability of the system in microgrids. Other purpose is to improve the voltage unbalance and harmonic compensation in stand-alone grids. The simulation of the system was developed by the Matlab/Simulink.

	Application of a MILP-based Algorithm for Power Flow Optimisation within More-Electric Aircraft Electrical Power Systems By Xin WANG	[View] [Download]
Abstract: This paper presents in detail how Mixed-Integer Linear Programming (MILP) can be used to solve the optimal power flow problem of Electrical Power Systems (EPSs) within More-Electric Aircraft (MEA). Continuous linear functions, integer variables and piecewise-linear functions are modelled to deal with bidirectional power flow, EPS control logic decisions, as well as non-linearity caused by efficiency curves.

	COOPERATIVE SECONDARY VOLTAGE CONTROL OF STATIC CONVERTERS IN A MICROGRID USING MODEL-FREE REINFORCEMENT LEARNING By Edward SMITH	[View] [Download]
Abstract: Agent-based secondary voltage regulation in an islanded MicroGrid is complicated by non-linear system dynamics, state couplings and uncertain communication network topology information. This paper proposes an off-policy learning algorithm for cooperative secondary voltage control which can synthesize an optimal feedback controller in real-time without knowledge of the system model. A simulation model has been developed using MATLAB/Simulink, which demonstrates a working controller. Results from the simulations are included, and practical considerations regarding implementation on a real system discussed.

	Estimation-based Consensus Approach for Decentralized Frequency Control of AC Microgrids By Yousef KHAYAT	[View] [Download]
Abstract: In this paper, a decentralized frequency control of ac microgrid (MG) governed by P-_ droop characteristics is presented. This approach is realized by applying an active power estimation to eliminate the required communication infrastructure in the secondary control layer. The proposed decentralized frequency control is achieved by employing the unique feature of the frequency as a global variable in autonomous ac MGs. By utilizing a consensus protocol, the proposed method restores the MG frequency to the nominal value while maintaining accurate power sharing of the droop mechanism. The consensus protocol is an estimation-based approach and does not require communication infrastructure. Experimental results verified accurate power-sharing and the frequency restoration to the nominal value without any communication requirement.

	Fault Detection in DC Microgrid using Teager Energy Operation on Wavelet-coefficients By Miao LI	[View] [Download]
Abstract: Reliable operation of DC Microgrid (MG) in real time demands for efficient protection system design which solely depends on fault detection at the incipient stage. This paper proposes a fault detection algorithm which combines the features of both DWT and Teager energy operator to detect short circuit fault in DC MG. Firstly, the instantaneous fault current is decomposed in the frequency domain using sliding window based discrete wavelet transform. The mother wavelet for the decomposition is properly chosen by comparing different existing wavelets. Secondly, the teager energy of the rate of change of the coefficients derived from wavelet synthesis is calculated and considered as the potential parameter to detect and distinguish between the arcing as well as bus faults in a DC MG. The simulation model is developed using MATLAB/SIMULINK to report the results.

	Model Predictive Energy Management for Sustainable Off-Shore Oil and Gas Platforms By Luca BIGARELLI	[View] [Download]
Abstract: This paper proposes a Two-Level Hierarchical Model Predictive Energy Management method (MPEM) for off-shore oil platforms with renewables. An economic cost function is at the basis of the High-Level controller, while a tracking cost function is designed for the Low-Level control layer. The power sources, the load and possible variation of the wind profile have been properly modeled. The control structure has been validated through simulations carried out in the MATLAB environment. Results are presented for different scenarios, which prove the robustness and effectiveness of the proposed control strategy.

	Model Validation of Power Electronics-based Networked Micro-grids by Prony Analysis By Mobin NADERI	[View] [Download]
Abstract: In this paper, a complete small signal model of two networked microgrids (NMGs) is provided, whichcan be used in the stability analysis, stability margin derivation and controller design. This model isvalidated by comparing it with the simulated NMGs using the Prony analysis. In this method, the modes, calculated by eigenvalue analysis and contributing to a particular state variable, are identified using the participation matrix and compared with the natural frequencies of its waveform. The state variable waveform is locally measured from the simulated NMGs in the SimPowerSystems environment of MATLAB and its natural frequencies are calculated using Prony analysis. It is concluded that Pronyanalysis estimates the natural frequencies well and there is a good similarity between them and thecalculated modes, which shows the modeling validation.

	Modeling and Real-Time Simulation of a DC Shipboard Microgrid By Federico SILVESTRO	[View] [Download]
Abstract: This paper illustrates the modelling of a Low Voltage DC ship electrical system, including batteries and variable speed generators, and its implementation on the Opal-RT real-time simulator. There is more and more necessity to represent the full dynamics of the component and relative control to have a proper knowledge of the behavior of the system. The use of digital twin is becoming more and more attractive in order to have a complete and reliable tool to assess the system behavior in all conditions. The coupling of variable speed generator and BESS (Battery Energy Storage Systems) is an efficient solution in order to improve energy efficiency on board of marine vessel and it is necessary in different SECA areas that have strong environmental requirements. Results show the effectiveness of the proposed simulation platform and the results obtained by the implementation of a droop-based power control strategy.

	V-dP/dI droop control technique with d²P/dI² to improve steady state performance for multiple PV modules in a dc microgrid By Wing Chun CHAN	[View] [Download]
Abstract: DC microgrids have been widely used in distributed generation networks due to intermittent nature of renewables, low conversion losses, common interface with dc renewable sources and high reliability. In order to regulate the dc bus voltage and achieve proportional power sharing, the conventional V-dP/dV droop control strategy is performed by calculating the slope of tangent of P-V characteristic. However, the main challenges of this control scheme are poor dynamic behaviour and low quality of PV power. This paper presents a decentralized coordinated PV droop control method, which applies dP/dI for accurate energy distribution and faster response speed. Moreover, the inner control parameter d2P/dI2 is used to further minimize the PV power fluctuation in a steady state which allows to track the error with a corrective action. The proposed control strategy seamlessly transfers the MPPT algorithm to voltage regulation mode in a fully decentralized approach. Simulation study is conducted to demonstrate how the transient and dynamic responses have been significantly improved.