EPE Association: EPE 1995 - 28 - Dialogue Session DS1d: HVDC, Transmission and Generator Systems

EPE 1995 - 28 - Dialogue Session DS1d: HVDC, Transmission and Generator Systems
You are here: EPE Documents > 01 - EPE & EPE ECCE Conference Proceedings > EPE 1995 - Conference > EPE 1995 - 28 - Dialogue Session DS1d: HVDC, Transmission and Generator Systems

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   LOW ORDER HARMONIC INSTABILITY OF HVDC SYSTEMS USING DESCRIBING FUNCTION
By A. I. Taalab [View]
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Abstract: In this paper the prediction of harmonic instabilitities or limit cycles which may exist in HVDC systems, using describing function technique, is presented. These instabilities are caused due to the presence of low order uncharacteristic harmonics at the input of the converter firing system through the DC current control loop. These low order harmonic may exist due to distorted or unbalanced AC voltage or firing system error and or interharmonics. A computer model is developed to compute the system describing functions at different magnitude, phase and harmonic frequency of the control modulating input signal. The envelope of the inverses of the describing functions for each harmonic component can be determined. Therefore, domain of the limit cycle boundary for each harmonic can be obtained in the log magnitude-phase angle plane. The limit cycle instability is examined with two quoted types of current control linear part transfer functions. The corresponding domains of the critical control gains and time constants is computed for different degrees of AC systems imbalance and distortion.

   NOVEL CONTROL STRATEGY OF DOUBLE-FED INDUCTION MACHINES
By S. Tnani; S. Diop; S. R. Jones; A. Berthon [View]
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Abstract: In the paper the authors propose a novel control strategy for double-fed induction machines operated as generator. The method is based on an open loop dynamic model and an identification of the load The approach is validated by simulations and on a microcontroller board. The obtained results show that this control method has high dynamic performances.

   REAL-TIME INTELLIGENT CONTROL FOR A MULTI-TERMINAL DIRECT CURRENT TRANSMISSION SYSTEM
By V. Shyam; H. S. Chandrasekharaiah; L. L. Lai [View]
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Abstract: This paper presents the use of a real-time intelligent controller in the form as an expert system for on-line monitoring and control of a Multi-terminal Direct Current Transmission (MTDC) system. The expert system comprises of a two-level blackboard architecture. This is implemented on a four node transputer-based multiprocessing system along with an intelligent high speed data acquisition system (IDAS). The dc converters considered in this paper are based on the sine-wave pulse width modulation (SPWM) technology. In this case the triggering strategy is more complex, but the resulting system control yields a number of advantages which cannot be realized otherwise. A novel firing pulse generator (FPG) hardware with suitable interface to the IDAS makes it possible to perform this task in real-time. Satisfactory results will be included to confirm the developed concept and technique.

EPE 1995 - 28 - Dialogue Session DS1d: HVDC, Transmission and Generator Systems
You are here: EPE Documents > 01 - EPE & EPE ECCE Conference Proceedings > EPE 1995 - Conference > EPE 1995 - 28 - Dialogue Session DS1d: HVDC, Transmission and Generator Systems
	[return to parent folder]

	LOW ORDER HARMONIC INSTABILITY OF HVDC SYSTEMS USING DESCRIBING FUNCTION By A. I. Taalab	[View] [Download]
Abstract: In this paper the prediction of harmonic instabilitities or limit cycles which may exist in HVDC systems, using describing function technique, is presented. These instabilities are caused due to the presence of low order uncharacteristic harmonics at the input of the converter firing system through the DC current control loop. These low order harmonic may exist due to distorted or unbalanced AC voltage or firing system error and or interharmonics. A computer model is developed to compute the system describing functions at different magnitude, phase and harmonic frequency of the control modulating input signal. The envelope of the inverses of the describing functions for each harmonic component can be determined. Therefore, domain of the limit cycle boundary for each harmonic can be obtained in the log magnitude-phase angle plane. The limit cycle instability is examined with two quoted types of current control linear part transfer functions. The corresponding domains of the critical control gains and time constants is computed for different degrees of AC systems imbalance and distortion.

	NOVEL CONTROL STRATEGY OF DOUBLE-FED INDUCTION MACHINES By S. Tnani; S. Diop; S. R. Jones; A. Berthon	[View] [Download]
Abstract: In the paper the authors propose a novel control strategy for double-fed induction machines operated as generator. The method is based on an open loop dynamic model and an identification of the load The approach is validated by simulations and on a microcontroller board. The obtained results show that this control method has high dynamic performances.

	REAL-TIME INTELLIGENT CONTROL FOR A MULTI-TERMINAL DIRECT CURRENT TRANSMISSION SYSTEM By V. Shyam; H. S. Chandrasekharaiah; L. L. Lai	[View] [Download]
Abstract: This paper presents the use of a real-time intelligent controller in the form as an expert system for on-line monitoring and control of a Multi-terminal Direct Current Transmission (MTDC) system. The expert system comprises of a two-level blackboard architecture. This is implemented on a four node transputer-based multiprocessing system along with an intelligent high speed data acquisition system (IDAS). The dc converters considered in this paper are based on the sine-wave pulse width modulation (SPWM) technology. In this case the triggering strategy is more complex, but the resulting system control yields a number of advantages which cannot be realized otherwise. A novel firing pulse generator (FPG) hardware with suitable interface to the IDAS makes it possible to perform this task in real-time. Satisfactory results will be included to confirm the developed concept and technique.