Mats Larsson - Academia.edu (original) (raw)
Papers by Mats Larsson
This paper describes experience with modal estimation tools for monitoring oscillations in the EN... more This paper describes experience with modal estimation tools for monitoring oscillations in the ENTSO-E continental European power system. A brief description of the tools and the wide-area monitoring system (WAMS) used by Swissgrid is given. The most important use cases are described and illustrated using recordings from actual events. The main use cases for the information provided by the WAMS at Swissgrid for planning and daily operation are discussed.
Recent major blackouts have exposed the vulnerability of power transmission networks. Often such ... more Recent major blackouts have exposed the vulnerability of power transmission networks. Often such blackouts are caused or aggravated by the overloading of equipment. The resulting tripping shifts the overload to other lines. A rolling blackout can ensue with its negative consequences on the productivity of companies and the safety and comfort of people. In most cases, the scope of the damage can be limited by operators taking the right decisions at the right time. This in turn requires information to be available in an easily accessible form. ABB is bringing innovations to the control room. Graphical displays show the load on all lines and help identify the weakest links. Network topology is also matched with geographical and environmental data – operators can identify lines that are at risk of failing due to the weather or vegetation.
Power Engineering Society, IEEE Winter Meeting, 2000
Traditionally the simulation of transient and voltage stability in power systems has been constra... more Traditionally the simulation of transient and voltage stability in power systems has been constrained to tools developed specifically for this purpose, e.g. Simpow, PSS/E, ETMSP and Eurostag. While being efficient and thereby able to simulate large systems, their component models are often encapsulated and difficult or impossible to examine and modify. Also, these simulators often require substantial training and are
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](IEEE Control Systems, 2010
2013 IEEE Power & Energy Society General Meeting, 2013
Dealing with large AC systems interfaced with DC grids through converters poses new challenges on... more Dealing with large AC systems interfaced with DC grids through converters poses new challenges on simulation platforms. A linearized model is essential for many common control design procedures while various converter control mode implementations are required to emulate different operating conditions in the DC grid. Currently many of the domain specific tools are unable to provide such linearized model when the model contains DC Grid components. To overcome this limitation of the domain specific simulation platforms, it is proposed to use the general purpose modeling language Modelica and the tool Dymola to generate linear models to develop extensions for controller design while PowerFactory Digsilent is used for time domain simulations. In this way it is possible to validate the actual system performance of the controller which is designed based on the linearized model. In this paper VSC HVDC is considered for the DC grid.
IEEE Transactions on Power Systems, 2004
Rapport technique, Corporate Research ABB Schweiz …, 2002
This report describes a test case intended for test of control synthesis and analysis of hybrid s... more This report describes a test case intended for test of control synthesis and analysis of hybrid systems. The test case illustrates voltage stability and the emergency control that may be necessary to avoid collapse and the subsequent blackout in the power system following ...
Lecture Notes in Control and Information Sciences, 2004
This chapter presents an overview of recent results on an approach to total control of power syst... more This chapter presents an overview of recent results on an approach to total control of power systems. It is upwards compatible from any conventional or prior advanced control and provides a framework for coordinated development of control to address all major dynamical problems. The approach appears applicable to complex systems generally where behaviour is influenced by nonlinearity, large-scale, uncertainty and hybrid nature. In particular, the presence of bifurcations of various kinds is allowed for while using ideas from switching and optimal control. The approach will be illustrated by consideration of coordinated control for transient stability, voltage regulation and emergency voltage control of power systems.
2004 43rd IEEE Conference on Decision and Control (CDC) (IEEE Cat. No.04CH37601), 2004
Recent blackouts have shown that traditional local protection against power system collapse is no... more Recent blackouts have shown that traditional local protection against power system collapse is not always sufficient to arrest instabilities. This paper shows that centralized systems can perform better than traditional local protection, as well as outlining how the decision logic of such centralized systems can be implemented. We present a coordinated system protection scheme (SPS) against voltage collapse based on model predictive control and heuristic tree search. It coordinates dissimilar and discrete controls such as generator, tap changer and load shedding controls in presence of soft and hard constraints on controls as well as voltages and currents in the network. The response with the coordinated SPS is compared to an SPS based on local measurements using simulation of the Nordic 32 test system. In terms of the amount of load shedding required to restore voltage stability, the simulations indicate that load shedding based on local criteria is near optimal in the system studied. However, when also generator controls are considered as emergency controls, the coordinated scheme reduces the amount of required load shedding by 35% compared to the local scheme.
Proceedings of the 44th IEEE Conference on Decision and Control
Wide-area phasor measurements and modern communication techniques will provide access to system-w... more Wide-area phasor measurements and modern communication techniques will provide access to system-wide frequency data with high accuracy and small time delay. This will make it possible also to monitor and control also relatively fast phenomena such as frequency instability using centralized approaches. This paper describes the decision logic of a centralized emergency frequency controller based on predictive control. A single machine equivalent for each power system island is computed online using phasor measurements. Using this model the progression of frequency stability after a contingency is monitored and stabilizing load shedding is determined in a coordinated way for the supervised area of the power system.
2003 European Control Conference (ECC), 2003
IFAC Proceedings Volumes, 2003
Transmission corridors between interconnected power systems or within countrywide transmission sy... more Transmission corridors between interconnected power systems or within countrywide transmission systems are limiting network performance or even market activities. We describe a state-of-the-art wide-area measurement system which is commercially available, and a new method to assess the voltage stability of a transmission corridor. Using only topological information, several lines can be grouped into a so-called virtual transmission corridor, whose parameters can be calculated from wide-area measurements. A simple computational procedure for stability analysis, makes it possible to provide approximate stability margins with an update rate of less than a second.
A relationship between a temperature T1 of a power line or power transmission conductor 10, an el... more A relationship between a temperature T1 of a power line or power transmission conductor 10, an electrical quantity of the power line such as a current I or power flow P through the power line, as well as meteorological quantities or ambient conditions of the power line such as wind speed W, wind direction, humidity, solar radiation S and ambient temperatureTa, is established in the form of a thermal model of the power line. Values of the aforementioned quantities or variables are continuously measured, and the collected values of the quantities are evaluated in order to update model parameters of the thermal model during operation of the power line. In a preferred embodiment of the invention, an average temperature representative of the entire line is determined via two Phasor Measurement Units (PMU) 11, 11 ' providing synchronized phasor values from two ends of the power line. An ohmic resistance of the power line is computed from the phasor values, from which in turn the average line temperature can be derived.
CIGRE/IEEE PES International Symposium, 2003
With the emphasis on higher utilization of power systems, monitoring of its dynamics is becoming ... more With the emphasis on higher utilization of power systems, monitoring of its dynamics is becoming increasingly important. This requires information with higher accuracy and update rates faster than those usually provided by traditional SCADA systems. In addition, it must be synchronized over a wider geographical area than that provided by traditional protection systems. The introduction of phasor measurement units as
This paper describes experience with modal estimation tools for monitoring oscillations in the EN... more This paper describes experience with modal estimation tools for monitoring oscillations in the ENTSO-E continental European power system. A brief description of the tools and the wide-area monitoring system (WAMS) used by Swissgrid is given. The most important use cases are described and illustrated using recordings from actual events. The main use cases for the information provided by the WAMS at Swissgrid for planning and daily operation are discussed.
Recent major blackouts have exposed the vulnerability of power transmission networks. Often such ... more Recent major blackouts have exposed the vulnerability of power transmission networks. Often such blackouts are caused or aggravated by the overloading of equipment. The resulting tripping shifts the overload to other lines. A rolling blackout can ensue with its negative consequences on the productivity of companies and the safety and comfort of people. In most cases, the scope of the damage can be limited by operators taking the right decisions at the right time. This in turn requires information to be available in an easily accessible form. ABB is bringing innovations to the control room. Graphical displays show the load on all lines and help identify the weakest links. Network topology is also matched with geographical and environmental data – operators can identify lines that are at risk of failing due to the weather or vegetation.
Power Engineering Society, IEEE Winter Meeting, 2000
Traditionally the simulation of transient and voltage stability in power systems has been constra... more Traditionally the simulation of transient and voltage stability in power systems has been constrained to tools developed specifically for this purpose, e.g. Simpow, PSS/E, ETMSP and Eurostag. While being efficient and thereby able to simulate large systems, their component models are often encapsulated and difficult or impossible to examine and modify. Also, these simulators often require substantial training and are
IEEE Control Systems, 2010
2013 IEEE Power & Energy Society General Meeting, 2013
Dealing with large AC systems interfaced with DC grids through converters poses new challenges on... more Dealing with large AC systems interfaced with DC grids through converters poses new challenges on simulation platforms. A linearized model is essential for many common control design procedures while various converter control mode implementations are required to emulate different operating conditions in the DC grid. Currently many of the domain specific tools are unable to provide such linearized model when the model contains DC Grid components. To overcome this limitation of the domain specific simulation platforms, it is proposed to use the general purpose modeling language Modelica and the tool Dymola to generate linear models to develop extensions for controller design while PowerFactory Digsilent is used for time domain simulations. In this way it is possible to validate the actual system performance of the controller which is designed based on the linearized model. In this paper VSC HVDC is considered for the DC grid.
IEEE Transactions on Power Systems, 2004
Rapport technique, Corporate Research ABB Schweiz …, 2002
This report describes a test case intended for test of control synthesis and analysis of hybrid s... more This report describes a test case intended for test of control synthesis and analysis of hybrid systems. The test case illustrates voltage stability and the emergency control that may be necessary to avoid collapse and the subsequent blackout in the power system following ...
Lecture Notes in Control and Information Sciences, 2004
This chapter presents an overview of recent results on an approach to total control of power syst... more This chapter presents an overview of recent results on an approach to total control of power systems. It is upwards compatible from any conventional or prior advanced control and provides a framework for coordinated development of control to address all major dynamical problems. The approach appears applicable to complex systems generally where behaviour is influenced by nonlinearity, large-scale, uncertainty and hybrid nature. In particular, the presence of bifurcations of various kinds is allowed for while using ideas from switching and optimal control. The approach will be illustrated by consideration of coordinated control for transient stability, voltage regulation and emergency voltage control of power systems.
2004 43rd IEEE Conference on Decision and Control (CDC) (IEEE Cat. No.04CH37601), 2004
Recent blackouts have shown that traditional local protection against power system collapse is no... more Recent blackouts have shown that traditional local protection against power system collapse is not always sufficient to arrest instabilities. This paper shows that centralized systems can perform better than traditional local protection, as well as outlining how the decision logic of such centralized systems can be implemented. We present a coordinated system protection scheme (SPS) against voltage collapse based on model predictive control and heuristic tree search. It coordinates dissimilar and discrete controls such as generator, tap changer and load shedding controls in presence of soft and hard constraints on controls as well as voltages and currents in the network. The response with the coordinated SPS is compared to an SPS based on local measurements using simulation of the Nordic 32 test system. In terms of the amount of load shedding required to restore voltage stability, the simulations indicate that load shedding based on local criteria is near optimal in the system studied. However, when also generator controls are considered as emergency controls, the coordinated scheme reduces the amount of required load shedding by 35% compared to the local scheme.
Proceedings of the 44th IEEE Conference on Decision and Control
Wide-area phasor measurements and modern communication techniques will provide access to system-w... more Wide-area phasor measurements and modern communication techniques will provide access to system-wide frequency data with high accuracy and small time delay. This will make it possible also to monitor and control also relatively fast phenomena such as frequency instability using centralized approaches. This paper describes the decision logic of a centralized emergency frequency controller based on predictive control. A single machine equivalent for each power system island is computed online using phasor measurements. Using this model the progression of frequency stability after a contingency is monitored and stabilizing load shedding is determined in a coordinated way for the supervised area of the power system.
2003 European Control Conference (ECC), 2003
IFAC Proceedings Volumes, 2003
Transmission corridors between interconnected power systems or within countrywide transmission sy... more Transmission corridors between interconnected power systems or within countrywide transmission systems are limiting network performance or even market activities. We describe a state-of-the-art wide-area measurement system which is commercially available, and a new method to assess the voltage stability of a transmission corridor. Using only topological information, several lines can be grouped into a so-called virtual transmission corridor, whose parameters can be calculated from wide-area measurements. A simple computational procedure for stability analysis, makes it possible to provide approximate stability margins with an update rate of less than a second.
A relationship between a temperature T1 of a power line or power transmission conductor 10, an el... more A relationship between a temperature T1 of a power line or power transmission conductor 10, an electrical quantity of the power line such as a current I or power flow P through the power line, as well as meteorological quantities or ambient conditions of the power line such as wind speed W, wind direction, humidity, solar radiation S and ambient temperatureTa, is established in the form of a thermal model of the power line. Values of the aforementioned quantities or variables are continuously measured, and the collected values of the quantities are evaluated in order to update model parameters of the thermal model during operation of the power line. In a preferred embodiment of the invention, an average temperature representative of the entire line is determined via two Phasor Measurement Units (PMU) 11, 11 ' providing synchronized phasor values from two ends of the power line. An ohmic resistance of the power line is computed from the phasor values, from which in turn the average line temperature can be derived.
CIGRE/IEEE PES International Symposium, 2003
With the emphasis on higher utilization of power systems, monitoring of its dynamics is becoming ... more With the emphasis on higher utilization of power systems, monitoring of its dynamics is becoming increasingly important. This requires information with higher accuracy and update rates faster than those usually provided by traditional SCADA systems. In addition, it must be synchronized over a wider geographical area than that provided by traditional protection systems. The introduction of phasor measurement units as