EPE Association: NORpie 2008 - Topic 05: CONTROL METHODS

NORpie 2008 - Topic 05: CONTROL METHODS
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   StatCom with Capacitive Energy Storage for Compensation of Cyclic Loads
By Hailian Xie, Lennart Angquist, Hans-Peter Nee [View]
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Abstract: Pulsating power consumption of a cyclic load may cause considerable disturbances in the voltage at the connection point. A StatCom can be employed to maintain the bus voltage level. With the integration of energy storage to the StatCom, the power quality at the connection point can be further improved by the additional active power compensation capability. This paper studies the control strategy for a StatCom with capacitive energy storage for compensation of a cyclic load. Simulations verify the proposed control scheme and show that both the phase jump and magnitude deviation of the bus voltage can be reduced by means of reactive and active power compensation.

   Grid Inductance Estimation by Reactive Power Perturbation for Sensor-less Scheme Based on Virtual Flux
By Arkadiusz Kulka, Tore Undeland [View]
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Abstract: Use of renewable energy sources is raising for grid connected systems, for which higher power quality requirements are being issued. Monitoring the grid impedance ensure stable operation of the controller and proper connection and disconnection from the grid. Thus it is vital to know the value of grid or transformer distributed impedance in given time, instead assuming a constant value in controller. To overcome this problem an identification method based on perturbation of reactive power is proposed. The normally inductive character of the grid used together with synchronous frame current controller have cross coupling terms which are used in analysis. This method is suitable for use with virtual flux oriented control. It uses two current sensors and one dc link voltage sensor. Method enables maintain unity power factor not only at PCC but also further into the grid, including lines and transformer leakage inductance.

   Understanding of tuning techniques of converter controllers for VSC-HVDC
By Chandra Bajracharya, Marta Molinas, Jon Are Suul, Tore M Undeland [View]
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Abstract: A mathematical model of a voltage source converter is presented in the synchronous reference frame for investigating VSC-HVDC for transferring wind power through a long distance. This model is used to analyze voltage and current control loops for the VSC and study their dynamics. Vector control is used for decoupled control of active and reactive power and the transfer functions are derived for the control loops. In investigating the operating conditions for HVDC systems, the tuning of controllers is one of the critical stages of the design of control loops. Three tuning techniques are discussed in the paper and analytical expressions are derived for calculating the parameters of the current and voltage controllers. The tuning criteria are discussed and simulations are used to test the performance of such tuning techniques.

   Active Control of Radial Rotor Vibrations in Electric Machines â€“ Identification, Modeling and Control Design
By Juha Orivuori, Antti Laiho, Anssi Sinervo [View]
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Abstract: This paper presents results related to modeling, identification, control design and simulation of an electric motor equipped with a new force actuator. The model consists of several partial models, thus separating certain physical phenomena into independent processes. The inputs and outputs of the models to be identified are strongly correlated. This makes the identification process significantly more complicated. Three different control algorithms are designed for the process. The performance of the control algorithms are tested against finite element models in extensive simulations. The paper concludes in description of preliminary test results with an actual test machine.

NORpie 2008 - Topic 05: CONTROL METHODS
You are here: EPE Documents > 05 - EPE Supported Conference Proceedings > NORpie - Proceedings > NORpie 2008 > NORpie 2008 - Topic 05: CONTROL METHODS
	[return to parent folder]

	StatCom with Capacitive Energy Storage for Compensation of Cyclic Loads By Hailian Xie, Lennart Angquist, Hans-Peter Nee	[View] [Download]
Abstract: Pulsating power consumption of a cyclic load may cause considerable disturbances in the voltage at the connection point. A StatCom can be employed to maintain the bus voltage level. With the integration of energy storage to the StatCom, the power quality at the connection point can be further improved by the additional active power compensation capability. This paper studies the control strategy for a StatCom with capacitive energy storage for compensation of a cyclic load. Simulations verify the proposed control scheme and show that both the phase jump and magnitude deviation of the bus voltage can be reduced by means of reactive and active power compensation.

	Grid Inductance Estimation by Reactive Power Perturbation for Sensor-less Scheme Based on Virtual Flux By Arkadiusz Kulka, Tore Undeland	[View] [Download]
Abstract: Use of renewable energy sources is raising for grid connected systems, for which higher power quality requirements are being issued. Monitoring the grid impedance ensure stable operation of the controller and proper connection and disconnection from the grid. Thus it is vital to know the value of grid or transformer distributed impedance in given time, instead assuming a constant value in controller. To overcome this problem an identification method based on perturbation of reactive power is proposed. The normally inductive character of the grid used together with synchronous frame current controller have cross coupling terms which are used in analysis. This method is suitable for use with virtual flux oriented control. It uses two current sensors and one dc link voltage sensor. Method enables maintain unity power factor not only at PCC but also further into the grid, including lines and transformer leakage inductance.

	Understanding of tuning techniques of converter controllers for VSC-HVDC By Chandra Bajracharya, Marta Molinas, Jon Are Suul, Tore M Undeland	[View] [Download]
Abstract: A mathematical model of a voltage source converter is presented in the synchronous reference frame for investigating VSC-HVDC for transferring wind power through a long distance. This model is used to analyze voltage and current control loops for the VSC and study their dynamics. Vector control is used for decoupled control of active and reactive power and the transfer functions are derived for the control loops. In investigating the operating conditions for HVDC systems, the tuning of controllers is one of the critical stages of the design of control loops. Three tuning techniques are discussed in the paper and analytical expressions are derived for calculating the parameters of the current and voltage controllers. The tuning criteria are discussed and simulations are used to test the performance of such tuning techniques.

	Active Control of Radial Rotor Vibrations in Electric Machines â€“ Identification, Modeling and Control Design By Juha Orivuori, Antti Laiho, Anssi Sinervo	[View] [Download]
Abstract: This paper presents results related to modeling, identification, control design and simulation of an electric motor equipped with a new force actuator. The model consists of several partial models, thus separating certain physical phenomena into independent processes. The inputs and outputs of the models to be identified are strongly correlated. This makes the identification process significantly more complicated. Three different control algorithms are designed for the process. The performance of the control algorithms are tested against finite element models in extensive simulations. The paper concludes in description of preliminary test results with an actual test machine.