EPE Association: EPE 1985 - 32 - Dialogue Session 2.1: DIALOGUE / POSTER SESSION (II)

EPE 1985 - 32 - Dialogue Session 2.1: DIALOGUE / POSTER SESSION (II)
You are here: EPE Documents > 01 - EPE & EPE ECCE Conference Proceedings > EPE 1985 - Conference > EPE 1985 - 32 - Dialogue Session 2.1: DIALOGUE / POSTER SESSION (II)

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   ENGINEERING ALGORITHM FOR OPTIMAL CONTROL OF DIGITALLY-CONTROLLED THYRISTOR CONVERTERS
By F. L. Luo; R. Hill [View]
[Download]

Abstract: This paper describes an engineering algorithm for optimal control of digitally-controlled thyristor converters based on Pontryagin's Maximum Principle. The algorithm optimises the digital control system and simplifies the further calculations necessary for the control of multi-loop systems with a current inner loop.

   MODERN PERFORMANCE POWER ANALYSIS IN CASE OF DISTORED CURVES AND MIXED VALUES IN SINGLE- AND MULTIPLE PHASE CIRCUITS
By E. Kohlhauser [View]
[Download]

Abstract: The first section of this paper describes the general requirements of power measurements under different conditions and discusses suitable methods. In continuation two modern solutions are presented, the AC-POWER ANALYZER D5155 and the AC/DC POWER ANALYZER D5135. The main features are explained, and finally a short summary is given on the practical applications of both instruments.

   SYNCHRONOUS MACHINES WITH ACTIVE DAMPING FOR POWER SYSTEM STABILIZATION
By U. J. Bichler [View]
[Download]

Abstract: The oscillatory response of synchronous generators connected to the power-line has several disadvantages. One is that the prime mover and the generator shaft are experiencing additional stresses by the oscillating electrical torque. On the other hand the power system is disturbed by hunting generators and the associated power transients. This paper deals with new solutions for improving the transient performance of the synchronous machine, which have become available with the recent advantages of microprocessors. A first step is to reduce the destabilizing effect of the voltage regulator using a conventional generator. Further, two active damping schemes for synchronous machines, in particular these with a second field winding in the quadrature axis, are described. The method employing generators of normal construction enhances damping very well under load, but becomes ineffective at light- or no-load conditions, while the machine with two axes rotor results in a perfect, decoupled and well damped performance under all load conditions. Following computer studies, all control schemes were tested in the laboratory using a 5KW synchronous machine with salient poles and microprocessor control. The results are presented below.

   FORMATION OF OUTPUT CURRENT OF VOLTAGE-FED INVERTER WITH APPLICATION OF ALTER-POLAR MODULATION
By M. A. Dzieniakowski; H. Tunia [View]
[Download]

Abstract: In the paper a new formation method of output current of voltage-fed inverter with follow-up control system, based on alter-polar modulation, is presented. There is also included an analytical analysis of the time-function of output current in case of arbitrary reference signal. This analysis leads to simple formulas for determing most important system parameters and may create a basis for the inverters with the follow-up control system design. A comparison between alter-polar, bipolar and unipolar modulation was made too. It was shown, among others, that the alter-polar modulation gives the smaller commutation losses in the inverter. The theoretical results are compared to the precise numerical calculations and the laboratory tests.

   AMELIORATION OF THE RESOLUTION OF A SHAFT POSITION SENSOR
By C. Nasr; R. Brimaud; C. Glaize [View]
[Download]

Abstract: This paper describes the conception and the realization of a frequency multiplier associated with a very simple 6 pts/rev shaft position encoder in order to increase artificially its resolution. A way to decrease dramatically the jitter of the frequency of the output is also shown.

   ANALYTICAL STUDY OF AN AC-REGULATOR, TRANSFORMER, 3-PHASE RESISTIVE LOAD ASSEMBLY
By J. L. Cocquerelle; C. Rombaut; M. Flacher [View]
[Download]

Abstract: The SCR'S of the three-phase A.C. regulator, placed between the three-phased power supply and the primary coils of a transformer which supplies a balanced resistant load, operate in a free switch-off situation. The operation of the assembly is closely dependent on the transformer and the charge. The authors carry out an overall analytical study, enabling the characteristics of the converter to be obtained and put in graph form.

   THE APPLICATION OF SWITCHED-CONDENSER CONCEPT IN POWER ELECTRONICS
By I. Nagy [View]
[Download]

Abstract: Significant progress, new concept in one field of engineering can beneficiently enrich another field. The switched condenser concept had been developed in communication engineering to substitute the resistor of inferior property in integrated circuits. The objective of the paper is to explore the feasibilities of this concept in power electronics. Following this train of thought, the paper arrives at some new configurations and offers new approach to the solution of a number of problems in power electronics. Their advantageous features are as follow. Due to their high frequency operation they have fast response and there is no need of bulky and expensive chokes. Their dynamic property can continuously be changed by the switching frequency. Wide variety of energy convergions can be solved by applying some basic circuits.

   ADAPTIVE STRUCTURE ALGORITHM FOR MICROPROCESSOR CONTROL OF DC MOTORS
By I. Dumitrache; S. Dumitriu; Fl. Munteanu [View]
[Download]

Abstract: In recent years the developments in VLSI technology have greatly reduced cost and improved performances of microprocessors and their peripherals. Microprocessors allow more and more the low cost implementation of sophisticated control functions and digital algorithms in industrial applications including electrical drives. In the same time, the present development of microprocessor-based control systems of electrical drives implies also a reconsideration of the classical design methods by providing new possibilities for practical implementation of optimal and adaptive control strategies. This paper describes an adaptive variable structure control algorithm for the speed control of a d.c. motor fed by a thyristor converter. This adaptive control algorithm is elaborated on the basis of a variable structure discrete-time mathematical model of the process. The control algorithm is synthesized in order to ensure an optimal behaviour - minimum settling time - in both continuous and discontinuous current modes of thyristor converter. Some implementation peculiarities of the adaptive variable structure control algorithm on a dedicated microcontroller based on standard 8080 microprocessor are emphasized.

   ANALYSIS OF FORCED COMMUTATED TECHNIQUES FOR AC-DC CONVERTERS
By M. H. Rashid; M. Aboudeana [View]
[Download]

Abstract: Three types of forced-commutated ac-dc converters which use symmetrical angle control, extinction angle control and PWM techniques are analysed. Although the extinction angle control technique provides a leading power factor, the PWM technique has the best power factor over a wide range of output voltage.

   AUTOMATIC CONTROL OF STREET LIGHTING BY THYRISTOR CONTROLLER
By A. K. Datta; A. K. Ghosh; A. Ray; P. K. Banerjee [View]
[Download]

Abstract: Control of illumination of level in the street lighting always remains a problem for fluctuating ambient condition due to fog, smog, haze, etc. Advancement in power electronics for large power control alongwith microelectronics make it possible to suggest schemes for illumination level control in the street lighting. Some special control characteristics can also be incorporated into such an automatic control scheme. This paper suggests a thyristor controlled power electronic scheme for automatic control of illumination and ON-OFF of street lights suitable for SON lamp. Power to SON lamp is fed via thyristor power electronic controller, operating in a closed loop feed-back circuit. The feedback circuit consists of a balanced bridge with LDR in one arm, which sets the desired illumination level. Any deviation from the set illumination level due to ambient conditions gives an actuating signal to the thyristor controller via trigger circuits. The operation is such that any reduction of ground illumination level will increase the voltage to the SON lamps so that the ground illumination always remain constant within a tolerable limit. The other feed-back loops actuates the ON and OFF conditions of the SON lamps.

   A NEWLY-CONCEIVED AC/DC STATIC CONVERTER FOR WIND POWER PLANTS
By V. Brunetti; F. Crescimbini; G. Sangiovanni [View]
[Download]

Abstract: Starting from some consideration on wind power plants, it is pointed out how a good exploitation of aeolian source is connected to the production of electric power with variable voltage and frequency in a large field of values. A kind of plant with an inverter supplied from an AC/DC converter is proposed: the attention is given to the characteristics necessary in order to satisfy the demands of wind power plants. A small power prototype realized with a N-MOS power transistor is shown. All the components, both power and control, are of a commercial type. The results of the test, carried out on the prototype, are demonstrated in conclusion. They indicate some of the converter working characteristics in the various operative modalities of the system.

   REDUCTION OF HARMONIC DISTORTION IN AUTONOMY MAINS LOADED BY THYRISTOR CONVERTERS USING RESONANT FILTERS
By J. Simic; B. Kovac [View]
[Download]

Abstract: The paper deals with reduction of harmonic distortion caused by thyristor converters using resonant filters. The methods for calculation of higher current harmonics and the filter design are given. The distortion factor is also calculated with and without filters. An expression is given that connects voltage distortions before and after filter connection. Some experimental results are also given, and they are very close to the ones obtained by measurements.

   IMPLEMENTATION OF A CONTROL AND MONITORING SYSTEM FOR POWER CONVERTERS
By J. Peracaula; J. A. Sabate; J. Bordonau [View]
[Download]

Abstract: The digital control of a SCR power converter for an electrical machine drive requires a fast microprocessor working on a real time basis. The addition of monitoring functions to such a system shows to be very useful and improves the overall performances. The use of two different 8 bit microprocessors, for the tasks of control and monitoring, facilitates the choice of the best suited microprocessor characteristics according to the function to be carried out. Here a microprocessor of the 8051 family and a Z80 have been selected respectively for control and monitoring functions and the advantages of this double microprocessor solution are explained emphasizing the work disminution of the control CPU thanks to the contribution of the monitoring CPU.

EPE 1985 - 32 - Dialogue Session 2.1: DIALOGUE / POSTER SESSION (II)
You are here: EPE Documents > 01 - EPE & EPE ECCE Conference Proceedings > EPE 1985 - Conference > EPE 1985 - 32 - Dialogue Session 2.1: DIALOGUE / POSTER SESSION (II)
	[return to parent folder]

	ENGINEERING ALGORITHM FOR OPTIMAL CONTROL OF DIGITALLY-CONTROLLED THYRISTOR CONVERTERS By F. L. Luo; R. Hill	[View] [Download]
Abstract: This paper describes an engineering algorithm for optimal control of digitally-controlled thyristor converters based on Pontryagin's Maximum Principle. The algorithm optimises the digital control system and simplifies the further calculations necessary for the control of multi-loop systems with a current inner loop.

	MODERN PERFORMANCE POWER ANALYSIS IN CASE OF DISTORED CURVES AND MIXED VALUES IN SINGLE- AND MULTIPLE PHASE CIRCUITS By E. Kohlhauser	[View] [Download]
Abstract: The first section of this paper describes the general requirements of power measurements under different conditions and discusses suitable methods. In continuation two modern solutions are presented, the AC-POWER ANALYZER D5155 and the AC/DC POWER ANALYZER D5135. The main features are explained, and finally a short summary is given on the practical applications of both instruments.

	SYNCHRONOUS MACHINES WITH ACTIVE DAMPING FOR POWER SYSTEM STABILIZATION By U. J. Bichler	[View] [Download]
Abstract: The oscillatory response of synchronous generators connected to the power-line has several disadvantages. One is that the prime mover and the generator shaft are experiencing additional stresses by the oscillating electrical torque. On the other hand the power system is disturbed by hunting generators and the associated power transients. This paper deals with new solutions for improving the transient performance of the synchronous machine, which have become available with the recent advantages of microprocessors. A first step is to reduce the destabilizing effect of the voltage regulator using a conventional generator. Further, two active damping schemes for synchronous machines, in particular these with a second field winding in the quadrature axis, are described. The method employing generators of normal construction enhances damping very well under load, but becomes ineffective at light- or no-load conditions, while the machine with two axes rotor results in a perfect, decoupled and well damped performance under all load conditions. Following computer studies, all control schemes were tested in the laboratory using a 5KW synchronous machine with salient poles and microprocessor control. The results are presented below.

	FORMATION OF OUTPUT CURRENT OF VOLTAGE-FED INVERTER WITH APPLICATION OF ALTER-POLAR MODULATION By M. A. Dzieniakowski; H. Tunia	[View] [Download]
Abstract: In the paper a new formation method of output current of voltage-fed inverter with follow-up control system, based on alter-polar modulation, is presented. There is also included an analytical analysis of the time-function of output current in case of arbitrary reference signal. This analysis leads to simple formulas for determing most important system parameters and may create a basis for the inverters with the follow-up control system design. A comparison between alter-polar, bipolar and unipolar modulation was made too. It was shown, among others, that the alter-polar modulation gives the smaller commutation losses in the inverter. The theoretical results are compared to the precise numerical calculations and the laboratory tests.

	AMELIORATION OF THE RESOLUTION OF A SHAFT POSITION SENSOR By C. Nasr; R. Brimaud; C. Glaize	[View] [Download]
Abstract: This paper describes the conception and the realization of a frequency multiplier associated with a very simple 6 pts/rev shaft position encoder in order to increase artificially its resolution. A way to decrease dramatically the jitter of the frequency of the output is also shown.

	ANALYTICAL STUDY OF AN AC-REGULATOR, TRANSFORMER, 3-PHASE RESISTIVE LOAD ASSEMBLY By J. L. Cocquerelle; C. Rombaut; M. Flacher	[View] [Download]
Abstract: The SCR'S of the three-phase A.C. regulator, placed between the three-phased power supply and the primary coils of a transformer which supplies a balanced resistant load, operate in a free switch-off situation. The operation of the assembly is closely dependent on the transformer and the charge. The authors carry out an overall analytical study, enabling the characteristics of the converter to be obtained and put in graph form.

	THE APPLICATION OF SWITCHED-CONDENSER CONCEPT IN POWER ELECTRONICS By I. Nagy	[View] [Download]
Abstract: Significant progress, new concept in one field of engineering can beneficiently enrich another field. The switched condenser concept had been developed in communication engineering to substitute the resistor of inferior property in integrated circuits. The objective of the paper is to explore the feasibilities of this concept in power electronics. Following this train of thought, the paper arrives at some new configurations and offers new approach to the solution of a number of problems in power electronics. Their advantageous features are as follow. Due to their high frequency operation they have fast response and there is no need of bulky and expensive chokes. Their dynamic property can continuously be changed by the switching frequency. Wide variety of energy convergions can be solved by applying some basic circuits.

	ADAPTIVE STRUCTURE ALGORITHM FOR MICROPROCESSOR CONTROL OF DC MOTORS By I. Dumitrache; S. Dumitriu; Fl. Munteanu	[View] [Download]
Abstract: In recent years the developments in VLSI technology have greatly reduced cost and improved performances of microprocessors and their peripherals. Microprocessors allow more and more the low cost implementation of sophisticated control functions and digital algorithms in industrial applications including electrical drives. In the same time, the present development of microprocessor-based control systems of electrical drives implies also a reconsideration of the classical design methods by providing new possibilities for practical implementation of optimal and adaptive control strategies. This paper describes an adaptive variable structure control algorithm for the speed control of a d.c. motor fed by a thyristor converter. This adaptive control algorithm is elaborated on the basis of a variable structure discrete-time mathematical model of the process. The control algorithm is synthesized in order to ensure an optimal behaviour - minimum settling time - in both continuous and discontinuous current modes of thyristor converter. Some implementation peculiarities of the adaptive variable structure control algorithm on a dedicated microcontroller based on standard 8080 microprocessor are emphasized.

	ANALYSIS OF FORCED COMMUTATED TECHNIQUES FOR AC-DC CONVERTERS By M. H. Rashid; M. Aboudeana	[View] [Download]
Abstract: Three types of forced-commutated ac-dc converters which use symmetrical angle control, extinction angle control and PWM techniques are analysed. Although the extinction angle control technique provides a leading power factor, the PWM technique has the best power factor over a wide range of output voltage.

	AUTOMATIC CONTROL OF STREET LIGHTING BY THYRISTOR CONTROLLER By A. K. Datta; A. K. Ghosh; A. Ray; P. K. Banerjee	[View] [Download]
Abstract: Control of illumination of level in the street lighting always remains a problem for fluctuating ambient condition due to fog, smog, haze, etc. Advancement in power electronics for large power control alongwith microelectronics make it possible to suggest schemes for illumination level control in the street lighting. Some special control characteristics can also be incorporated into such an automatic control scheme. This paper suggests a thyristor controlled power electronic scheme for automatic control of illumination and ON-OFF of street lights suitable for SON lamp. Power to SON lamp is fed via thyristor power electronic controller, operating in a closed loop feed-back circuit. The feedback circuit consists of a balanced bridge with LDR in one arm, which sets the desired illumination level. Any deviation from the set illumination level due to ambient conditions gives an actuating signal to the thyristor controller via trigger circuits. The operation is such that any reduction of ground illumination level will increase the voltage to the SON lamps so that the ground illumination always remain constant within a tolerable limit. The other feed-back loops actuates the ON and OFF conditions of the SON lamps.

	A NEWLY-CONCEIVED AC/DC STATIC CONVERTER FOR WIND POWER PLANTS By V. Brunetti; F. Crescimbini; G. Sangiovanni	[View] [Download]
Abstract: Starting from some consideration on wind power plants, it is pointed out how a good exploitation of aeolian source is connected to the production of electric power with variable voltage and frequency in a large field of values. A kind of plant with an inverter supplied from an AC/DC converter is proposed: the attention is given to the characteristics necessary in order to satisfy the demands of wind power plants. A small power prototype realized with a N-MOS power transistor is shown. All the components, both power and control, are of a commercial type. The results of the test, carried out on the prototype, are demonstrated in conclusion. They indicate some of the converter working characteristics in the various operative modalities of the system.

	REDUCTION OF HARMONIC DISTORTION IN AUTONOMY MAINS LOADED BY THYRISTOR CONVERTERS USING RESONANT FILTERS By J. Simic; B. Kovac	[View] [Download]
Abstract: The paper deals with reduction of harmonic distortion caused by thyristor converters using resonant filters. The methods for calculation of higher current harmonics and the filter design are given. The distortion factor is also calculated with and without filters. An expression is given that connects voltage distortions before and after filter connection. Some experimental results are also given, and they are very close to the ones obtained by measurements.

	IMPLEMENTATION OF A CONTROL AND MONITORING SYSTEM FOR POWER CONVERTERS By J. Peracaula; J. A. Sabate; J. Bordonau	[View] [Download]
Abstract: The digital control of a SCR power converter for an electrical machine drive requires a fast microprocessor working on a real time basis. The addition of monitoring functions to such a system shows to be very useful and improves the overall performances. The use of two different 8 bit microprocessors, for the tasks of control and monitoring, facilitates the choice of the best suited microprocessor characteristics according to the function to be carried out. Here a microprocessor of the 8051 family and a Z80 have been selected respectively for control and monitoring functions and the advantages of this double microprocessor solution are explained emphasizing the work disminution of the control CPU thanks to the contribution of the monitoring CPU.