EPE Association: EPE 2011 - DS1c: Topic 16: Microgrid Control and HVDC Transmission

EPE 2011 - DS1c: Topic 16: Microgrid Control and HVDC Transmission
You are here: EPE Documents > 01 - EPE & EPE ECCE Conference Proceedings > EPE 2011 ECCE Europe - Conference > EPE 2011 - Topic 16: Power electronics in transmission and distribution > EPE 2011 - DS1c: Topic 16: Microgrid Control and HVDC Transmission

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   A comparison of Two Methods of Estimating Losses in the M2C Converter
By Colin OATES, Colin DAVIDSON [View]
[Download]

Abstract: The transmission losses in an HVDC interconnection represent lost revenue to the purchaser (usually a transmission Utility) and are therefore heavily penalised. At the bid stage, the purchaser calculates the Net Present Value (NPV) of the revenue lost due to power losses over the operating life of the system (typically 30 years) and uses this to derive a loss capitalisation value which is typically in the range of 4000€/kW. Bidders are required to calculate and guarantee the power losses of the converter station under certain idealised operating conditions. Presently there is no agreed method for calculating the losses for the Multi Modular Converter (MMC). This paper presents a mathematical analysis for calculating both the conduction and switching losses for a VSC HVDC station using the MMC topology, comparing it to an equivalent model based on MATLAB/Simulink model. The results show very good agreement for conduction loss; however the error for the switching loss are much more significant and require further development.

   A Novel Parallel Voltage and Current Control Scheme Implementing P-F and Q-V Droop in a Microgrid
By Christopher ROWE, Terrence SUMMERS, Robert BETZ [View]
[Download]

Abstract: A novel droop controller is developed employing parallel voltage and current control algorithms. P-F droop is performed by a voltage controller in the direct axis of the rotating reference frame, whilst Q-V droop is achieved via a deadbeat current controller in the quadrature axis. Simulation and hardware results are presented to demonstrate the control schemes ability to provide matched and mismatched power sharing utilising a low voltage two inverter microgrid.

   Autonomous Operation of Hybrid Microgrid with AC and DC Sub-Grids
By Poh Chiang LOH, Frede BLAABJERG [View]
[Download]

Abstract: This paper investigates on the active and reactive power sharing of an autonomous hybrid microgrid. Unlike existing microgrids which are purely ac, the hybrid microgrid studied here comprises dc and ac sub-grids, interconnected by power electronic interfaces. The main challenge here is to manage the power flow among all the sources distributed throughout the two types of sub-grids, which certainly is tougher than previous efforts developed for only either ac or dc microgrid. This wider scope of control has not yet been investigated, and would certainly rely on the coordinated operation of dc sources, ac sources and interlinking converters. Suitable control and normalization schemes are therefore developed for controlling them with results presented for showing the overall performance of the hybrid microgrid.

   Comparison of Power Converter Circuits for HVDC with SMES
By Linn ZARCHI, Toshifumi ISE, Yushi MIURA, Hiroaki KAKIGANO [View]
[Download]

Abstract: This paper describes the comparison of circuit configuration of CSC (Current Source Converter) and VSC (Voltage Source Converter) in HVDC (High Voltage DC Transmission) with SMES (Superconducting Magnetic Energy Storage) connection. The purpose of using SMES is to smooth out power fluctuation in one terminal side in order to avoid causing power system instability and frequency deviation by absorbing or providing power according to the system requirement. Configurations of these two proposed system have ability for power system stabilization in the case of power fluctuation from natural energy source. To evaluate the performance of the applied circuit configurations and control methods, PSCAD/EMTDC simulation is used.

   Comparison of the Semiconductor Losses in Self Commutated Inverter Topologies for HVDC Applications
By Hans-Günter ECKEL, Jan RUNGE [View]
[Download]

Abstract: For self commutated HVDC systems, two-level and modular multi-level converters (M2LC) are used. In this paper, the M2LC is compared to cascaded two-level inverters. The necessary switching frequency for a given number of series connected two-level inverters is calculated, assuming the same stored energy in the inductances as the M2LC. The loss balance between upper and lower IGBT and between IGBT and diode is evaluated. The achievable output power, the efficiency and the surge current stress show a strong dependence on the switching frequency. So the main optimization parameter for output power and efficiency is the switching frequency, whereas the circuit topology has a strong impact on passive components and on the inverter performance under fault conditions.

   CONTROL STRATEGIES OF DC-BASED OFFSHORE WIND FARM
By Pascal MONJEAN, Jérôme DELANOE, Daniel MARIN, Jérôme AUGUSTE, Christophe SAUDEMONT, Benoît ROBYNS [View]
[Download]

Abstract: The interest about offshore wind farm (WF) has increased significantly during past years. Usually, localdistribution is achieved by an AC grid. For distance higher than 100 km, HVDC (High Voltage DirectCurrent) connection is used for power distribution from farm to shore. Considering the recent improve-ments of DC-DC converters and theirs impact on electrical architecture, the generalization of DC linkwithin the distribution scheme of the farm becomes easier and really interesting. In this paper, a windfarm topology is under study as well as different possible control strategies for converters. EspeciallyDC-DC converter in WT and in offshore platform. Firstly, several control strategies for offshore windfarm will be studied. Then, a global comparison of the different technical solutions has been done interms of :- advantages and drawbacks for each control strategy,- possible technological choices resulting from control scheme.Finally, a comparison about the control strategies for DC-DC converters for a wind farm topology isachieved by simulating Real-Time Simulations. Full-Bridge technology for DC-DC converter appearsto be a suitable solution given it has a simple control mode, and less expensive technology than DoubleActive Bridge DC-DC converter.

   Control Strategies of Microgrid with Hybrid DC and AC Buses
By Bo DONG, Yongdong LI, Zhixue ZHENG, Lie XU [View]
[Download]

Abstract: This paper focuses on control strategies of Microgrid which consists of wind turbines, photovoltaic panels, batteries and super-capacitors with Hybrid DC and AC Buses. In grid-connected operation, voltage of DC bus is kept steady by inverter and voltage and frequency of AC bus are the same with utility grid. Energy Management System controls hybrid storage system to release or absorb power with the strategies according to grid condition, state of charge of batteries and super-capacitor, electricity price and so on. In islanded operation, voltage of DC bus is controlled by storage system and amplitude and frequency of AC-Bus voltage are regulated by parallel inverters with voltage-frequency or droop control strategy. In this paper, different control strategies in grid-connected and islanded operation are described which can keep power balanced and AC/DC bus stable. Simulation and experimental results are shown to verify the proposed control method.

   DC-Link Voltage Ripple Minimization in a Hybrid Modular Multilevel Voltage Source Converter for HVDC Power Transmission
By Matteo TOMASINI, Ralph FELDMAN, Jon C. CLARE, Pat WHEELER, David R. TRAINER, Robert S. WHITEHOUSE [View]
[Download]

Abstract: This paper presents a method for DC-Link voltage ripple reduction for a recently proposed modular multilevel (M2C) hybrid voltage source converter intended for the HVDC market. A mode of operation is described that enables both control of the modulation index and reduction of the DC-Link voltage and current ripple. This is achieved by superimposing multiple triplen harmonic components to the rectified fundamental component synthesised by the M2C Chain-Link converter.

   Design of a Sustainable Residential Microgrid System Including PHEV and Energy Storage Device
By Leandro ROGGIA, Cassiano RECH, Luciano SCHUCH, José Eduardo BAGGIO, Hélio Leães HEY, José Renes PINHEIRO [View]
[Download]

Abstract: A sustainable residential microgrid composed of two distributed generation sources (photovoltaic panels and biofuel generator), one energy storage device (battery bank), and capable of supplying both AC and DC loads, including a plug-in hybrid electric vehicle, is proposed. The microgrid can operate in grid-connected mode and island mode. It is composed of a main DC bus and also an AC bus. The main features of the system, the operation modes description, selection of the supervisory system control method and results are presented in this paper.

   Diode Based HVDC Link for the Connection of Large Off-shore Wind Farms with Self Start Capability
By Ramon BLASCO-GIMENEZ, Salvador ANYO-VILLALBA, Johel RODRIGUEZ-DDERLEE, Soledad BERNAL-PEREZ [View]
[Download]

Abstract: This paper includes a distributed control strategy for the joint control of wind turbines and a diode based HVDC link with black start capability. In spite of using a Line Commutated Rectifier, the presented technique allows for the black-start operation of the off-shore grid. Moreover, an adequate desing of wind turbine pitch and active power control during the connection procedure allows for reduced mechanical stress on the wind turbines. The proposed self start strategy allows for the wind farm to carry out initial energization of the HVDC-link. Validation of the proposed technique at rated power and at cut-in wind speed has been carried out considering a distributed model of the wind farm.

   Fractional-Order Based Droop Control Of An Universal Wind-Turbine System
By Domenico RICCHIUTO, Marco LISERRE, Rosa Anna MASTROMAURO, Antonio DELL'AQUILA, Alberto PIGAZO [View]
[Download]

Abstract: In this paper it is investigated the use of fractional-order controllers for an universal operation of small-power wind turbine system. Universal inverters should be able to work both connected to the grid both in island mode. Proper active/reactive control strategies are needed to get system work in universal operation. The aim of this paper is to investigate the use of fractional PI (PIα) for active and reactive power control of an universal wind turbine system in order to achieve a better trade-off between dynamical response and stability. The effectiveness of the proposed control method is verified by simulation and experimental results.

   Implementation of harmonic control for a 3-phase 4-wire inverter with harmonic-loaded neutral
By Yanyun MA, Thomas ELLINGER, Jürgen PETZOLDT [View]
[Download]

Abstract: The paper presents a 3-phase 4-wire VSC with a single-phase unbalanced load. The voltage control loop is investigated in order to attenuate harmonics of the load voltage. The output voltage is transformed into DC quantities to control the inverter. This kind of inverter can be a good choice for the applications with hybrid power system based on renewable energy used to supply unbalanced harmonic loads. The fourth leg allows controlling the zero sequence components of the system. The paper consists of two main sections. The simulation is on the basis of MATLAB and implemented by DSP-programming. Simulation results are compared with experimental results for a prototype inverter to verify the validity of the proposed control strategy.

   Modeling and Simulation of Heat Pump Air Conditioning Unit Intending Energy Capacity Reduction of Energy Storage System in Microgrid
By Shunsuke KAWACHI, Jumpei BABA, Hiroto HAGIWARA, Shigeo NUMATA, Eisuke SHIMODA, Kei FURUKAWA [View]
[Download]

Abstract: To compensate power fluctuation caused by renewable energy sources, the concept of load control has been proposed. This concept is an idea to control the power consumption of loads in the power grid in order to contribute to the grid operator. In this paper, control of a heat pump air-conditioner is focused. Based on heat pump's characteristic obtained from experiments, a simple heat pump model is proposed. A simulation to compensate power fluctuation in a microgrid by use of the heat pump is conducted and the effect of the heat pump control is analyzed. The results of the simulation show that the necessary capacity of energy storage system(ESS) can be reduced by controlling the power consumption of the heat pump. At the same time, temperature simulation of the room which is air-conditioned by the heat pump is conducted to analyze the effect of load control to the user of the heat pump. The results show that the temperature fluctuation caused by load control is small enough to ensure the thermal comfort of the room. The feature of this paper is that the effect of the load control using a heat pump air-conditioner is discussed with consideration to the user's convenience.

   Small Signal Modelling and Stability Analysis of Multiterminal VSC-HVDC
By Aleisawee ALSSEID [View]
[Download]

Abstract: Two control strategies are implemented for multiterminal voltage sourced converter (VSC)-based HVDC (M-VSC-HVDC). A test system consisting of five terminals was developed in PSCAD. In-Strategy 1, the Predictive controller is implemented in the inner control loop whereas strategy 2 using proportional–integral–derivative controller (PID). Small signal analytical models for two terminal VSC-HVDC are developed within MATLAB. Simulation is performed using PSCAD to verify and validate the conclusions from the analytical models. A detailed comparison study between the two strategies is carried out. An eigenvalues stability study for very weak AC system is also presented. Strategy II is seen to be adequate for advanced control design for multiterminal M-VSC-HVDC system for higher power applications. The potential of the supplementary DC voltage feedback to enhance the dynamic stability is considered. It is shown that in order to enhance system robustness it is important to use additional DC voltage feedback with strategy II on all stations operating with DC current/power regulation. The simulation results show that the supplementary DC voltage feedback contribute significantly toward improving the dynamic behavior of the M-VSC-HVDC system under a wide range of operating conditions

   Wireless communication system for microgrids management in islanding
By Alvaro LLARIA, Octavian CUREA, Jaime JIMÉNEZ, José Luis MARTÍN, Aitzol ZULOAGA [View]
[Download]

Abstract: Microgrids (MGs) are promising electrical systems based on Distributed Generation and with high penetration of renewable energy sources. One important feature of MGs is the islanding capability: if there is a disturbance in the main grid, the MG will be automatically disconnected. In theory, once in islanding, the MG can continue the electrical generation but, in practice, the generation is stopped in order to avoid injuries and accidents. Therefore, the management systems utilized in MGs must be improved in order to allow a safe operation in islanding. This paper presents a wireless communication system for MGs management based on SimpliciTI protocol. The communication procedure, including security, and the MG controllers with their measure system are described in depth, and the correct operation of the proposed solution is also verified.

EPE 2011 - DS1c: Topic 16: Microgrid Control and HVDC Transmission
You are here: EPE Documents > 01 - EPE & EPE ECCE Conference Proceedings > EPE 2011 ECCE Europe - Conference > EPE 2011 - Topic 16: Power electronics in transmission and distribution > EPE 2011 - DS1c: Topic 16: Microgrid Control and HVDC Transmission
	[return to parent folder]

	A comparison of Two Methods of Estimating Losses in the M2C Converter By Colin OATES, Colin DAVIDSON	[View] [Download]
Abstract: The transmission losses in an HVDC interconnection represent lost revenue to the purchaser (usually a transmission Utility) and are therefore heavily penalised. At the bid stage, the purchaser calculates the Net Present Value (NPV) of the revenue lost due to power losses over the operating life of the system (typically 30 years) and uses this to derive a loss capitalisation value which is typically in the range of 4000€/kW. Bidders are required to calculate and guarantee the power losses of the converter station under certain idealised operating conditions. Presently there is no agreed method for calculating the losses for the Multi Modular Converter (MMC). This paper presents a mathematical analysis for calculating both the conduction and switching losses for a VSC HVDC station using the MMC topology, comparing it to an equivalent model based on MATLAB/Simulink model. The results show very good agreement for conduction loss; however the error for the switching loss are much more significant and require further development.

	A Novel Parallel Voltage and Current Control Scheme Implementing P-F and Q-V Droop in a Microgrid By Christopher ROWE, Terrence SUMMERS, Robert BETZ	[View] [Download]
Abstract: A novel droop controller is developed employing parallel voltage and current control algorithms. P-F droop is performed by a voltage controller in the direct axis of the rotating reference frame, whilst Q-V droop is achieved via a deadbeat current controller in the quadrature axis. Simulation and hardware results are presented to demonstrate the control schemes ability to provide matched and mismatched power sharing utilising a low voltage two inverter microgrid.

	Autonomous Operation of Hybrid Microgrid with AC and DC Sub-Grids By Poh Chiang LOH, Frede BLAABJERG	[View] [Download]
Abstract: This paper investigates on the active and reactive power sharing of an autonomous hybrid microgrid. Unlike existing microgrids which are purely ac, the hybrid microgrid studied here comprises dc and ac sub-grids, interconnected by power electronic interfaces. The main challenge here is to manage the power flow among all the sources distributed throughout the two types of sub-grids, which certainly is tougher than previous efforts developed for only either ac or dc microgrid. This wider scope of control has not yet been investigated, and would certainly rely on the coordinated operation of dc sources, ac sources and interlinking converters. Suitable control and normalization schemes are therefore developed for controlling them with results presented for showing the overall performance of the hybrid microgrid.

	Comparison of Power Converter Circuits for HVDC with SMES By Linn ZARCHI, Toshifumi ISE, Yushi MIURA, Hiroaki KAKIGANO	[View] [Download]
Abstract: This paper describes the comparison of circuit configuration of CSC (Current Source Converter) and VSC (Voltage Source Converter) in HVDC (High Voltage DC Transmission) with SMES (Superconducting Magnetic Energy Storage) connection. The purpose of using SMES is to smooth out power fluctuation in one terminal side in order to avoid causing power system instability and frequency deviation by absorbing or providing power according to the system requirement. Configurations of these two proposed system have ability for power system stabilization in the case of power fluctuation from natural energy source. To evaluate the performance of the applied circuit configurations and control methods, PSCAD/EMTDC simulation is used.

	Comparison of the Semiconductor Losses in Self Commutated Inverter Topologies for HVDC Applications By Hans-Günter ECKEL, Jan RUNGE	[View] [Download]
Abstract: For self commutated HVDC systems, two-level and modular multi-level converters (M2LC) are used. In this paper, the M2LC is compared to cascaded two-level inverters. The necessary switching frequency for a given number of series connected two-level inverters is calculated, assuming the same stored energy in the inductances as the M2LC. The loss balance between upper and lower IGBT and between IGBT and diode is evaluated. The achievable output power, the efficiency and the surge current stress show a strong dependence on the switching frequency. So the main optimization parameter for output power and efficiency is the switching frequency, whereas the circuit topology has a strong impact on passive components and on the inverter performance under fault conditions.

	CONTROL STRATEGIES OF DC-BASED OFFSHORE WIND FARM By Pascal MONJEAN, Jérôme DELANOE, Daniel MARIN, Jérôme AUGUSTE, Christophe SAUDEMONT, Benoît ROBYNS	[View] [Download]
Abstract: The interest about offshore wind farm (WF) has increased significantly during past years. Usually, localdistribution is achieved by an AC grid. For distance higher than 100 km, HVDC (High Voltage DirectCurrent) connection is used for power distribution from farm to shore. Considering the recent improve-ments of DC-DC converters and theirs impact on electrical architecture, the generalization of DC linkwithin the distribution scheme of the farm becomes easier and really interesting. In this paper, a windfarm topology is under study as well as different possible control strategies for converters. EspeciallyDC-DC converter in WT and in offshore platform. Firstly, several control strategies for offshore windfarm will be studied. Then, a global comparison of the different technical solutions has been done interms of :- advantages and drawbacks for each control strategy,- possible technological choices resulting from control scheme.Finally, a comparison about the control strategies for DC-DC converters for a wind farm topology isachieved by simulating Real-Time Simulations. Full-Bridge technology for DC-DC converter appearsto be a suitable solution given it has a simple control mode, and less expensive technology than DoubleActive Bridge DC-DC converter.

	Control Strategies of Microgrid with Hybrid DC and AC Buses By Bo DONG, Yongdong LI, Zhixue ZHENG, Lie XU	[View] [Download]
Abstract: This paper focuses on control strategies of Microgrid which consists of wind turbines, photovoltaic panels, batteries and super-capacitors with Hybrid DC and AC Buses. In grid-connected operation, voltage of DC bus is kept steady by inverter and voltage and frequency of AC bus are the same with utility grid. Energy Management System controls hybrid storage system to release or absorb power with the strategies according to grid condition, state of charge of batteries and super-capacitor, electricity price and so on. In islanded operation, voltage of DC bus is controlled by storage system and amplitude and frequency of AC-Bus voltage are regulated by parallel inverters with voltage-frequency or droop control strategy. In this paper, different control strategies in grid-connected and islanded operation are described which can keep power balanced and AC/DC bus stable. Simulation and experimental results are shown to verify the proposed control method.

	DC-Link Voltage Ripple Minimization in a Hybrid Modular Multilevel Voltage Source Converter for HVDC Power Transmission By Matteo TOMASINI, Ralph FELDMAN, Jon C. CLARE, Pat WHEELER, David R. TRAINER, Robert S. WHITEHOUSE	[View] [Download]
Abstract: This paper presents a method for DC-Link voltage ripple reduction for a recently proposed modular multilevel (M2C) hybrid voltage source converter intended for the HVDC market. A mode of operation is described that enables both control of the modulation index and reduction of the DC-Link voltage and current ripple. This is achieved by superimposing multiple triplen harmonic components to the rectified fundamental component synthesised by the M2C Chain-Link converter.

	Design of a Sustainable Residential Microgrid System Including PHEV and Energy Storage Device By Leandro ROGGIA, Cassiano RECH, Luciano SCHUCH, José Eduardo BAGGIO, Hélio Leães HEY, José Renes PINHEIRO	[View] [Download]
Abstract: A sustainable residential microgrid composed of two distributed generation sources (photovoltaic panels and biofuel generator), one energy storage device (battery bank), and capable of supplying both AC and DC loads, including a plug-in hybrid electric vehicle, is proposed. The microgrid can operate in grid-connected mode and island mode. It is composed of a main DC bus and also an AC bus. The main features of the system, the operation modes description, selection of the supervisory system control method and results are presented in this paper.

	Diode Based HVDC Link for the Connection of Large Off-shore Wind Farms with Self Start Capability By Ramon BLASCO-GIMENEZ, Salvador ANYO-VILLALBA, Johel RODRIGUEZ-DDERLEE, Soledad BERNAL-PEREZ	[View] [Download]
Abstract: This paper includes a distributed control strategy for the joint control of wind turbines and a diode based HVDC link with black start capability. In spite of using a Line Commutated Rectifier, the presented technique allows for the black-start operation of the off-shore grid. Moreover, an adequate desing of wind turbine pitch and active power control during the connection procedure allows for reduced mechanical stress on the wind turbines. The proposed self start strategy allows for the wind farm to carry out initial energization of the HVDC-link. Validation of the proposed technique at rated power and at cut-in wind speed has been carried out considering a distributed model of the wind farm.

	Fractional-Order Based Droop Control Of An Universal Wind-Turbine System By Domenico RICCHIUTO, Marco LISERRE, Rosa Anna MASTROMAURO, Antonio DELL'AQUILA, Alberto PIGAZO	[View] [Download]
Abstract: In this paper it is investigated the use of fractional-order controllers for an universal operation of small-power wind turbine system. Universal inverters should be able to work both connected to the grid both in island mode. Proper active/reactive control strategies are needed to get system work in universal operation. The aim of this paper is to investigate the use of fractional PI (PIα) for active and reactive power control of an universal wind turbine system in order to achieve a better trade-off between dynamical response and stability. The effectiveness of the proposed control method is verified by simulation and experimental results.

	Implementation of harmonic control for a 3-phase 4-wire inverter with harmonic-loaded neutral By Yanyun MA, Thomas ELLINGER, Jürgen PETZOLDT	[View] [Download]
Abstract: The paper presents a 3-phase 4-wire VSC with a single-phase unbalanced load. The voltage control loop is investigated in order to attenuate harmonics of the load voltage. The output voltage is transformed into DC quantities to control the inverter. This kind of inverter can be a good choice for the applications with hybrid power system based on renewable energy used to supply unbalanced harmonic loads. The fourth leg allows controlling the zero sequence components of the system. The paper consists of two main sections. The simulation is on the basis of MATLAB and implemented by DSP-programming. Simulation results are compared with experimental results for a prototype inverter to verify the validity of the proposed control strategy.

	Modeling and Simulation of Heat Pump Air Conditioning Unit Intending Energy Capacity Reduction of Energy Storage System in Microgrid By Shunsuke KAWACHI, Jumpei BABA, Hiroto HAGIWARA, Shigeo NUMATA, Eisuke SHIMODA, Kei FURUKAWA	[View] [Download]
Abstract: To compensate power fluctuation caused by renewable energy sources, the concept of load control has been proposed. This concept is an idea to control the power consumption of loads in the power grid in order to contribute to the grid operator. In this paper, control of a heat pump air-conditioner is focused. Based on heat pump's characteristic obtained from experiments, a simple heat pump model is proposed. A simulation to compensate power fluctuation in a microgrid by use of the heat pump is conducted and the effect of the heat pump control is analyzed. The results of the simulation show that the necessary capacity of energy storage system(ESS) can be reduced by controlling the power consumption of the heat pump. At the same time, temperature simulation of the room which is air-conditioned by the heat pump is conducted to analyze the effect of load control to the user of the heat pump. The results show that the temperature fluctuation caused by load control is small enough to ensure the thermal comfort of the room. The feature of this paper is that the effect of the load control using a heat pump air-conditioner is discussed with consideration to the user's convenience.

	Small Signal Modelling and Stability Analysis of Multiterminal VSC-HVDC By Aleisawee ALSSEID	[View] [Download]
Abstract: Two control strategies are implemented for multiterminal voltage sourced converter (VSC)-based HVDC (M-VSC-HVDC). A test system consisting of five terminals was developed in PSCAD. In-Strategy 1, the Predictive controller is implemented in the inner control loop whereas strategy 2 using proportional–integral–derivative controller (PID). Small signal analytical models for two terminal VSC-HVDC are developed within MATLAB. Simulation is performed using PSCAD to verify and validate the conclusions from the analytical models. A detailed comparison study between the two strategies is carried out. An eigenvalues stability study for very weak AC system is also presented. Strategy II is seen to be adequate for advanced control design for multiterminal M-VSC-HVDC system for higher power applications. The potential of the supplementary DC voltage feedback to enhance the dynamic stability is considered. It is shown that in order to enhance system robustness it is important to use additional DC voltage feedback with strategy II on all stations operating with DC current/power regulation. The simulation results show that the supplementary DC voltage feedback contribute significantly toward improving the dynamic behavior of the M-VSC-HVDC system under a wide range of operating conditions

	Wireless communication system for microgrids management in islanding By Alvaro LLARIA, Octavian CUREA, Jaime JIMÉNEZ, José Luis MARTÍN, Aitzol ZULOAGA	[View] [Download]
Abstract: Microgrids (MGs) are promising electrical systems based on Distributed Generation and with high penetration of renewable energy sources. One important feature of MGs is the islanding capability: if there is a disturbance in the main grid, the MG will be automatically disconnected. In theory, once in islanding, the MG can continue the electrical generation but, in practice, the generation is stopped in order to avoid injuries and accidents. Therefore, the management systems utilized in MGs must be improved in order to allow a safe operation in islanding. This paper presents a wireless communication system for MGs management based on SimpliciTI protocol. The communication procedure, including security, and the MG controllers with their measure system are described in depth, and the correct operation of the proposed solution is also verified.