EPE Association: EPE-PEMC 2000 - Topic 06c: Converters for Energy Systems

EPE-PEMC 2000 - Topic 06c: Converters for Energy Systems
You are here: EPE Documents > 04 - EPE-PEMC Conference Proceedings > EPE-PEMC 2000 - Conference > EPE-PEMC 2000 - Topic 06: Power Electronics in Electrical Energy Generation, Transmission and Distribution > EPE-PEMC 2000 - Topic 06c: Converters for Energy Systems

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   Application of Optimal Stabilizer and Variable Structure Controller for Power System Stability with Free Chattering
By Negm M.M.M. [View]
[Download]

Abstract: This paper proposes two novel techniques for improving the dynamic stability of power system. The first technique utilizes the optimal stabilizer with preview steps. The second technique makes use of the variable structure system and employs the generator speed to obtain a stabilizing signal to increase the damping torque of the synchronous machine. Supplementary stabilizing signals are also introduce into the power system to increase the damping torque of the synchronous machine. This improves the transient stability of the power system. The plant augmentation method is used to solve the existing control chattering problem. Augmenting the plant by a pure integrator places control chattering at the augmented plant input instead of the original plant input. The optimal stabilizer is synthesized and implemented and its applicability and robustness are demonstrated. The simulation results demonstrate that the proposed two techniques yield a good dynamic performance with less overshoot and shorter settling time in step response. These two techniques can be used as effective mean of increasing the damping torque and hence improving the dynamic stability of the power system.

   DC Component Control for Voltage Source Inverters with Turn-Off Devices
By Pichler P., Ebner P., Weiss H. [View]
[Download]

Abstract: The physical properties of semiconductor turn off devices including gate unit and control line are the reason for small variable delays when switching. From this an imbalance between the positive and the negative voltage-time-area over one period of the output voltage is created. At machines with a big air gap usually no severe problems will be encountered. However, if a high power transformer fed by the specific voltage source inverter is loaded with a small but distinctive continuous DC component in the voltage, a DC magnetisation of the iron core will occur. The heavy non-linearity of the iron core shall lead to single polarity peaks of the magnetising current even exceeding the rated current values. A special procedure for the determination of the magnetic imbalance enabling counteracting control measures is proposed. A robust design with easy implementation is presented finally.

   Main Synchronized Low Cost Solar Conversion for Household Applications
By Bulatov O., Obuchov S.*, Polyakov V.*, Obgerin F.*, Ertan B.** [View]
[Download]

Abstract: Efficiency of PV solar-electric conversion systems is quite low, when compared with incident energy from the sun. Such systems also occupy a large space on the roof of houses. The proposed system has the objective of increasing the efficiency of solar-electric conversion.The availability of electricity as energy form is very high and such energy is valuable. Especially in the sunny days of spring and summer an efficient solar-electric conversion system can reduce the energy demand from the grid and shave the peak load.

   Non-linear Voltage Control of a PWM Excited Induction Generator
By Peña R.*, Cárdenas R.*, Diz L.*, Blasco-Giménez R. [View]
[Download]

Abstract: A voltage control strategy of a variable speed induction generator supplying a DC bus bar, via a three-phase voltage-source current-regulated PWM inverter is presented. Indirect vector control technique is used to regulate the currents in the machine. The torque component q-axis current is used to regulate the DC link voltage whereas the d-axis current is used to keep the flux in the machine constant. Given the non-linear and time varying characteristic of the DC link voltage dynamic, the square of the DC voltage is controlled and feed-forward or load compensation is used. Simulation and experimental results showing the performance of the controller to load impacts and variable speed operation are presented.

   Static Frequency Converters for Energy Industry
By Paál E., Bojtor L. [View]
[Download]

Abstract: The paper focuses on the high power static frequency converters (SFC) for energy industry. The energy industry apply SFC starting gas turbo-sets and motor-turbine sets in pump storage power plants. The configuration of the main circuit and reduction of the harmonic contents on the grid generated by SFC are described. The control system based on sub-transient flux calculation makes possible to build up a sensorless solution.

EPE-PEMC 2000 - Topic 06c: Converters for Energy Systems
You are here: EPE Documents > 04 - EPE-PEMC Conference Proceedings > EPE-PEMC 2000 - Conference > EPE-PEMC 2000 - Topic 06: Power Electronics in Electrical Energy Generation, Transmission and Distribution > EPE-PEMC 2000 - Topic 06c: Converters for Energy Systems
	[return to parent folder]

	Application of Optimal Stabilizer and Variable Structure Controller for Power System Stability with Free Chattering By Negm M.M.M.	[View] [Download]
Abstract: This paper proposes two novel techniques for improving the dynamic stability of power system. The first technique utilizes the optimal stabilizer with preview steps. The second technique makes use of the variable structure system and employs the generator speed to obtain a stabilizing signal to increase the damping torque of the synchronous machine. Supplementary stabilizing signals are also introduce into the power system to increase the damping torque of the synchronous machine. This improves the transient stability of the power system. The plant augmentation method is used to solve the existing control chattering problem. Augmenting the plant by a pure integrator places control chattering at the augmented plant input instead of the original plant input. The optimal stabilizer is synthesized and implemented and its applicability and robustness are demonstrated. The simulation results demonstrate that the proposed two techniques yield a good dynamic performance with less overshoot and shorter settling time in step response. These two techniques can be used as effective mean of increasing the damping torque and hence improving the dynamic stability of the power system.

	DC Component Control for Voltage Source Inverters with Turn-Off Devices By Pichler P., Ebner P., Weiss H.	[View] [Download]
Abstract: The physical properties of semiconductor turn off devices including gate unit and control line are the reason for small variable delays when switching. From this an imbalance between the positive and the negative voltage-time-area over one period of the output voltage is created. At machines with a big air gap usually no severe problems will be encountered. However, if a high power transformer fed by the specific voltage source inverter is loaded with a small but distinctive continuous DC component in the voltage, a DC magnetisation of the iron core will occur. The heavy non-linearity of the iron core shall lead to single polarity peaks of the magnetising current even exceeding the rated current values. A special procedure for the determination of the magnetic imbalance enabling counteracting control measures is proposed. A robust design with easy implementation is presented finally.

	Main Synchronized Low Cost Solar Conversion for Household Applications By Bulatov O., Obuchov S., Polyakov V., Obgerin F., Ertan B.*	[View] [Download]
Abstract: Efficiency of PV solar-electric conversion systems is quite low, when compared with incident energy from the sun. Such systems also occupy a large space on the roof of houses. The proposed system has the objective of increasing the efficiency of solar-electric conversion.The availability of electricity as energy form is very high and such energy is valuable. Especially in the sunny days of spring and summer an efficient solar-electric conversion system can reduce the energy demand from the grid and shave the peak load.

	Non-linear Voltage Control of a PWM Excited Induction Generator By Peña R., Cárdenas R., Diz L., Blasco-Giménez R.*	[View] [Download]
Abstract: A voltage control strategy of a variable speed induction generator supplying a DC bus bar, via a three-phase voltage-source current-regulated PWM inverter is presented. Indirect vector control technique is used to regulate the currents in the machine. The torque component q-axis current is used to regulate the DC link voltage whereas the d-axis current is used to keep the flux in the machine constant. Given the non-linear and time varying characteristic of the DC link voltage dynamic, the square of the DC voltage is controlled and feed-forward or load compensation is used. Simulation and experimental results showing the performance of the controller to load impacts and variable speed operation are presented.

	Static Frequency Converters for Energy Industry By Paál E., Bojtor L.	[View] [Download]
Abstract: The paper focuses on the high power static frequency converters (SFC) for energy industry. The energy industry apply SFC starting gas turbo-sets and motor-turbine sets in pump storage power plants. The configuration of the main circuit and reduction of the harmonic contents on the grid generated by SFC are described. The control system based on sub-transient flux calculation makes possible to build up a sensorless solution.