Massimiliano Chiandone - Academia.edu (original) (raw)

Papers by Massimiliano Chiandone

The actions for limiting the climate change are significantly affecting the electrical power syst... more The actions for limiting the climate change are significantly affecting the electrical power system. Indeed, the increase in renewable power sources and the progressive shut off of coal-fired power plants are transitioning the generation from a centralized to a decentralized paradigm. The latter may cause issues in a grid that was originally designed taking as granted the presence of several big power plants to be used as actuators for the system control. Considering voltage control, the actual control architecture is based on a hierarchical structure applied to a given set of rigidly subdivided control areas. Although such architecture is currently capable of maintain voltage control on the grid, the increase in converter interfaced generators (due to renewables exploitation) and the decrease of the buses short circuit powers (due to high power plants shut-off) may decrease its effectiveness in the future. To this aim, in this paper a coordinated decoupling voltage control is proposed, capable of using all the available reactive power sources on the grid as actuators. The issue of controlling a system with a variable number of actuators (due to generators connection and disconnection) is taken into account, proposing a suitable solution for avoiding transients during the switch between controllers having different output dimension. A brief discussion about communication (among actuators and controller) performances required for implementing the proposed control in the power system is also given.

Several factors lead to the increase of Distributed Generation (DG), including the ongoing penetr... more Several factors lead to the increase of Distributed Generation (DG), including the ongoing penetration of electric power plants from renewable sources. However, most of present distribution networks have been designed as passive networks and present some relevant problems that prevent a strong penetration of DG. One of the major problems is the voltage rise due to active power injections made by distributed generators. This paper reviews control strategies that have been recently proposed to control the voltage profile of distribution networks and to mitigate voltage rise. A voltage rise mitigation strategy is then presented along with a mathematical formulation that encompasses both coordinated and local reactive power generation controls. A proposal for an implementation using smart control devices of the distributed generators is finally presented.

The aim of an electric power control system is to supply electric energy to final users ensuring ... more The aim of an electric power control system is to supply electric energy to final users ensuring an adequate quality regardless to the constant changes in network topology, the variations in generation and the load fluctuations within the system itself. This dissertation deals with the control aspects of one of the main parameters involved in the quality of the service provided: the voltage value energy is supplied. It is herewith not intended to look at the definition of adequate quality of energy. Over the years several devices have been developed to control the voltage value in different parts of the power system. This work aims at studying in deep some of the aspects of the voltage control systems regulating the reactive power absorbed and injected into the network by generators. Voltage regulation in electrical systems is traditionally divided at primary level by operating on the reactive power of the single generator and by controlling the reactive power of entire power stations at secondary level. Ultimately these regulations are both carried out by varying the current or the excitation voltage in synchronous generators. This work presents a single hardware and software platform enabling the implementation of two digitally controlled devices: - a control system controlling the excitation in synchronous generators; - a system controlling the reactive power of the secondary voltage control in large power plants. This device is prescribed in the Italian network code since 2003 and is called SART (Automatic System for Voltage Regulation). These voltage regulators were historically born as analog devices and were subsequently implemented as digital controls using various technologies. The central topic of this dissertation is the implementation of the above-mentioned devices as digital control systems using microprocessors and general purpose computing systems, fitted out with operating systems for general use but with real-time characteristics. An emerging technique to quickly prototype a control system implies the utilization of high level simulation tools to design and simulate the plant to be controlled and automatically generate a control code. This work presents in detail the above-mentioned technique in the production and regulation of electric energy. The two control systems taken into consideration are designed and simulated using a high-level language and implemented with a modified Linux operating system (RTAI) in order to offer real-time performance. Furthermore, the experimental data of some SART device commissioning sessions are also included. In conclusion, the possibility of using the same platform for the development of similar voltage control devices to apply in the distribution network was investigated. The growth of little and medium-sized generation units, within the distribution network, which has taken place in the last decade, has introduced new issues in voltage regulation. For this reason a new control strategy was suggested for voltage controlling in distribution networks, where the generation is spread and control devices similar to the ones presented for the transmission network can be applied.

Elsevier eBooks, 2021

This chapter discusses voltage controllers in distribution systems and their interactions with Co... more This chapter discusses voltage controllers in distribution systems and their interactions with Converter-Interfaced Generation (CIG). The focus of the chapter is on the long-term dynamic response of the system with particular emphasis on voltage stability analysis. Two scenarios are considered: (i) Under-Load Tap Changer (ULTC) transformers coupled with distribution networks that include wind generation; and (ii) a Secondary Voltage Regulation (SVR) that coordinates solar photo-voltaic power plants. Different models and implementations of the ULTC logic as well as of the SVR are considered and discussed in detail. The first scenario is concerned on the impact of CIG on the operation of ULTCs, while the second scenario discusses how CIG can effectively contribute to the voltage regulation of the network.

IEEE Electrification Magazine, Mar 1, 2023

Currently, the electric power generation and transmission systems are undergoing major changes, d... more Currently, the electric power generation and transmission systems are undergoing major changes, due to the increase in distributed power generation and the related decrease in conventional power plants. Moreover, to reduce the electric power system pollutants emissions, in Italy the decommissioning of coal-fired power plants is ongoing. As a result, the number of power plants capable of ensuring the secondary voltage control is dwindling, substituted by generators with less voltage regulation capabilities. To cope with such an issue, one of the possible solutions is the introduction of a new voltage regulation architecture. However, it is necessary to analyze the present secondary voltage regulation system, in order to evaluate how much of its control architecture can be kept, and where to intervene to improve it. To this aim, in this paper the assessment of the parameters affecting the behavior of the Italian secondary voltage regulation system is made, in terms of areas and pilot nodes determination. This is done by means of two different procedures, implemented with a software approach that allows for a partial automation of the process.

Distributed Generation is growing at important rates due to several reasons, including, in some c... more Distributed Generation is growing at important rates due to several reasons, including, in some countries, the strong penetration of renewable generating plants. Voltage rise is a considerable problem that prevents generators from injecting more active power into distribution networks. After a review of recently proposed mitigation techniques, a voltage rise mitigation technique is presented. The technique is based on a coordinated reactive power control of the distributed generators which takes into account the capability limits of the generators. It is suitable for utilization in distribution networks equipped with or without a dedicated communication infrastructure.

Hierarchical automatic voltage regulation is implemented in several power systems using the react... more Hierarchical automatic voltage regulation is implemented in several power systems using the reactive power capabilities of controlled alternators in transmission networks. With the introduction of power plants based on Renewable Energy Sources (RES), in the transmission network there are new possible participants to the voltage regulation which replace in part the traditional large alternators. The paper reviews the actual situation in Italy for the participation of renewable power plants to the transmission network voltage regulation.

Secondary Voltage Regulation (SVR) is part of the hierarchical control system of EHV transmission... more Secondary Voltage Regulation (SVR) is part of the hierarchical control system of EHV transmission network, currently operated by the Italian Independent System Operator. SVR is being actuated using automatic voltage and reactive power regulators, named SART, in power stations rated more than 100 MVA. Each SART receives from the Regional Voltage Regulator a reactive level signal and implements it by

European Conference on Power Electronics and Applications, Oct 6, 2009

Linux operative system, extended with the real time application interface (RTAI), makes it possib... more Linux operative system, extended with the real time application interface (RTAI), makes it possible to realize industrial motion controls. This requires general purpose processors (GPPs) instead of dedicated DSPs or microcontrollers. RTAI offers the possibility of designing and developing motion controls using high level object languages (i.e., Simulink). The main advantages brought using Linux-RTAI and a PC as a controller platform are: very reduced time for development, diagnostics, design of controls; cost reduction offered by the open-source status of the operating system; high availability of the hardware. This paper shows that such a system offers adequate digital programming and signal processing capabilities to make real time motion control applications. An industrial-PC based acceleration control is presented and points of strength of RTAI solution are shown.

The Internet of Things frameworks can improve quality and performance of controlled system but al... more The Internet of Things frameworks can improve quality and performance of controlled system but also leading the system to be weaker from the cyber security point of view: new devices can be used to exploit system vulnerabilities with malicious intentions. In this paper the effect of a cyber-attack in a modern all-electric ship Integrated Power System is investigated and an alternative paradigm is exploited with a view to enhancing the system security and reliability. The need for security by design has become crucial but it is not enough to prevent all the cyber-attacks and so the dependability theory approach is considered in order to avoid the undesired system failures.

This paper focuses on a possible evolution of the control architectures suitable for Integrated P... more This paper focuses on a possible evolution of the control architectures suitable for Integrated Power Systems in modern all-electric ships. In control systems there is a major trend in using information and telecommunication technology as general real-time operating systems and standard communication protocols. This trend leads a standardization at software and communication protocol level that is unavoidable considering the ever-increasing needs of integration of power electronics and control systems in shipboard Integrated Power Systems. Using Internet of Things protocol frameworks can improve quality and performance of controlled systems.

ABSTRACT Power quality is a key issue in islanded electric power systems. Considering the intrins... more ABSTRACT Power quality is a key issue in islanded electric power systems. Considering the intrinsic weakness of islanded grids, this paramount aspect is not of easy accomplishment. To fulfill power quality requirements in these weak electric systems, high performance voltage and frequency controls are needed, although the interactions between these controls can lead to stability issues. In particular, frequency and voltage controls' bandwidth overlapping may produce destabilizing actions. In this paper, a study of the electromechanical stability in shipboard integrated power systems is presented, with particular reference to the case in which voltage and frequency controls dynamically interact.

2014 International Conference on Renewable Energy Research and Application (ICRERA), Oct 1, 2014

Distributed Generation (DG) operating in a distribution network influences active power losses. I... more Distributed Generation (DG) operating in a distribution network influences active power losses. In this paper power losses have been estimated for an actual low voltage distribution network and compared for different situations according to the DG penetration and placement of the power units. A practical method to place new DGs is presented. The basic idea is to minimize power losses, while complying voltage network limits, calculated with power flows using historical data over a discrete number of possible points of connection.

This paper describes the design of the revamping of a hydro power plant and the starting method o... more This paper describes the design of the revamping of a hydro power plant and the starting method of its pump unit. Due to economical and technical constraints, it has been decided to use a synchronous machine with a direct connection to a synchronous generator. After the modeling of the power plant, it has been decided to start the synchronous motor asynchronously and then to synchronize it with the generator. Simulation of the possible starting sequence has been carried out and will be presented.

We calculate the historical payback time (PBT) and internal rate of return (IRR) for domestic pho... more We calculate the historical payback time (PBT) and internal rate of return (IRR) for domestic photovoltaic systems installed at different times between 2003 and 2014, in three different Italian locations (North, center, South, thus representing different levels of energy yield). We show that over time, even though rather different regimes of governmental incentivization and end-user energy prices existed, such economic parameters have hardly been affected. Remarkably, this is true even for the case of systems installed in 2014 - i.e. where no incentivization of any kind is considered, but grid parity has been attained. In this case the PBT is 10.6, 9.3, 8.5 years for the locations in the North, center, and South, respectively; the IRR is 9.1%, 10.4%, 11.3%, respectively. These observations are in marked contrast with the common understanding that the dramatic reduction of installations in Italy after 2011 is due to a reduction of the economic convenience for the end-user, suggesting that the economic factor only plays a marginal role in current PV market dynamics.

IEEE Transactions on Transportation Electrification, 2023

Institution of Engineering and Technology eBooks, Sep 15, 2022

The synchronous generators’ excitation is usually regulated by means of a real-time digital contr... more The synchronous generators’ excitation is usually regulated by means of a real-time digital control system, while other apparatuses are dedicated to secondary functions (e.g human machine interface, remote control unit, logic and control functions). A performance increase and a cost reduction can be achieved by integrating all the functions into a single platform. However, this requires assessing the dependability performance of the control systems currently in use, to set a base benchmark for future evaluations. In this paper, the quantitative dependability analysis of a digital excitation control system is performed, by using as a case study a real system installed in a hydroelectric power station. Two configurations are analyzed, and their dependability performance are compared.

The actions for limiting the climate change are significantly affecting the electrical power syst... more The actions for limiting the climate change are significantly affecting the electrical power system. Indeed, the increase in renewable power sources and the progressive shut off of coal-fired power plants are transitioning the generation from a centralized to a decentralized paradigm. The latter may cause issues in a grid that was originally designed taking as granted the presence of several big power plants to be used as actuators for the system control. Considering voltage control, the actual control architecture is based on a hierarchical structure applied to a given set of rigidly subdivided control areas. Although such architecture is currently capable of maintain voltage control on the grid, the increase in converter interfaced generators (due to renewables exploitation) and the decrease of the buses short circuit powers (due to high power plants shut-off) may decrease its effectiveness in the future. To this aim, in this paper a coordinated decoupling voltage control is proposed, capable of using all the available reactive power sources on the grid as actuators. The issue of controlling a system with a variable number of actuators (due to generators connection and disconnection) is taken into account, proposing a suitable solution for avoiding transients during the switch between controllers having different output dimension. A brief discussion about communication (among actuators and controller) performances required for implementing the proposed control in the power system is also given.

Several factors lead to the increase of Distributed Generation (DG), including the ongoing penetr... more Several factors lead to the increase of Distributed Generation (DG), including the ongoing penetration of electric power plants from renewable sources. However, most of present distribution networks have been designed as passive networks and present some relevant problems that prevent a strong penetration of DG. One of the major problems is the voltage rise due to active power injections made by distributed generators. This paper reviews control strategies that have been recently proposed to control the voltage profile of distribution networks and to mitigate voltage rise. A voltage rise mitigation strategy is then presented along with a mathematical formulation that encompasses both coordinated and local reactive power generation controls. A proposal for an implementation using smart control devices of the distributed generators is finally presented.

The aim of an electric power control system is to supply electric energy to final users ensuring ... more The aim of an electric power control system is to supply electric energy to final users ensuring an adequate quality regardless to the constant changes in network topology, the variations in generation and the load fluctuations within the system itself. This dissertation deals with the control aspects of one of the main parameters involved in the quality of the service provided: the voltage value energy is supplied. It is herewith not intended to look at the definition of adequate quality of energy. Over the years several devices have been developed to control the voltage value in different parts of the power system. This work aims at studying in deep some of the aspects of the voltage control systems regulating the reactive power absorbed and injected into the network by generators. Voltage regulation in electrical systems is traditionally divided at primary level by operating on the reactive power of the single generator and by controlling the reactive power of entire power stations at secondary level. Ultimately these regulations are both carried out by varying the current or the excitation voltage in synchronous generators. This work presents a single hardware and software platform enabling the implementation of two digitally controlled devices: - a control system controlling the excitation in synchronous generators; - a system controlling the reactive power of the secondary voltage control in large power plants. This device is prescribed in the Italian network code since 2003 and is called SART (Automatic System for Voltage Regulation). These voltage regulators were historically born as analog devices and were subsequently implemented as digital controls using various technologies. The central topic of this dissertation is the implementation of the above-mentioned devices as digital control systems using microprocessors and general purpose computing systems, fitted out with operating systems for general use but with real-time characteristics. An emerging technique to quickly prototype a control system implies the utilization of high level simulation tools to design and simulate the plant to be controlled and automatically generate a control code. This work presents in detail the above-mentioned technique in the production and regulation of electric energy. The two control systems taken into consideration are designed and simulated using a high-level language and implemented with a modified Linux operating system (RTAI) in order to offer real-time performance. Furthermore, the experimental data of some SART device commissioning sessions are also included. In conclusion, the possibility of using the same platform for the development of similar voltage control devices to apply in the distribution network was investigated. The growth of little and medium-sized generation units, within the distribution network, which has taken place in the last decade, has introduced new issues in voltage regulation. For this reason a new control strategy was suggested for voltage controlling in distribution networks, where the generation is spread and control devices similar to the ones presented for the transmission network can be applied.

Elsevier eBooks, 2021

This chapter discusses voltage controllers in distribution systems and their interactions with Co... more This chapter discusses voltage controllers in distribution systems and their interactions with Converter-Interfaced Generation (CIG). The focus of the chapter is on the long-term dynamic response of the system with particular emphasis on voltage stability analysis. Two scenarios are considered: (i) Under-Load Tap Changer (ULTC) transformers coupled with distribution networks that include wind generation; and (ii) a Secondary Voltage Regulation (SVR) that coordinates solar photo-voltaic power plants. Different models and implementations of the ULTC logic as well as of the SVR are considered and discussed in detail. The first scenario is concerned on the impact of CIG on the operation of ULTCs, while the second scenario discusses how CIG can effectively contribute to the voltage regulation of the network.

IEEE Electrification Magazine, Mar 1, 2023

Currently, the electric power generation and transmission systems are undergoing major changes, d... more Currently, the electric power generation and transmission systems are undergoing major changes, due to the increase in distributed power generation and the related decrease in conventional power plants. Moreover, to reduce the electric power system pollutants emissions, in Italy the decommissioning of coal-fired power plants is ongoing. As a result, the number of power plants capable of ensuring the secondary voltage control is dwindling, substituted by generators with less voltage regulation capabilities. To cope with such an issue, one of the possible solutions is the introduction of a new voltage regulation architecture. However, it is necessary to analyze the present secondary voltage regulation system, in order to evaluate how much of its control architecture can be kept, and where to intervene to improve it. To this aim, in this paper the assessment of the parameters affecting the behavior of the Italian secondary voltage regulation system is made, in terms of areas and pilot nodes determination. This is done by means of two different procedures, implemented with a software approach that allows for a partial automation of the process.

Distributed Generation is growing at important rates due to several reasons, including, in some c... more Distributed Generation is growing at important rates due to several reasons, including, in some countries, the strong penetration of renewable generating plants. Voltage rise is a considerable problem that prevents generators from injecting more active power into distribution networks. After a review of recently proposed mitigation techniques, a voltage rise mitigation technique is presented. The technique is based on a coordinated reactive power control of the distributed generators which takes into account the capability limits of the generators. It is suitable for utilization in distribution networks equipped with or without a dedicated communication infrastructure.

Hierarchical automatic voltage regulation is implemented in several power systems using the react... more Hierarchical automatic voltage regulation is implemented in several power systems using the reactive power capabilities of controlled alternators in transmission networks. With the introduction of power plants based on Renewable Energy Sources (RES), in the transmission network there are new possible participants to the voltage regulation which replace in part the traditional large alternators. The paper reviews the actual situation in Italy for the participation of renewable power plants to the transmission network voltage regulation.

Secondary Voltage Regulation (SVR) is part of the hierarchical control system of EHV transmission... more Secondary Voltage Regulation (SVR) is part of the hierarchical control system of EHV transmission network, currently operated by the Italian Independent System Operator. SVR is being actuated using automatic voltage and reactive power regulators, named SART, in power stations rated more than 100 MVA. Each SART receives from the Regional Voltage Regulator a reactive level signal and implements it by

European Conference on Power Electronics and Applications, Oct 6, 2009

Linux operative system, extended with the real time application interface (RTAI), makes it possib... more Linux operative system, extended with the real time application interface (RTAI), makes it possible to realize industrial motion controls. This requires general purpose processors (GPPs) instead of dedicated DSPs or microcontrollers. RTAI offers the possibility of designing and developing motion controls using high level object languages (i.e., Simulink). The main advantages brought using Linux-RTAI and a PC as a controller platform are: very reduced time for development, diagnostics, design of controls; cost reduction offered by the open-source status of the operating system; high availability of the hardware. This paper shows that such a system offers adequate digital programming and signal processing capabilities to make real time motion control applications. An industrial-PC based acceleration control is presented and points of strength of RTAI solution are shown.

The Internet of Things frameworks can improve quality and performance of controlled system but al... more The Internet of Things frameworks can improve quality and performance of controlled system but also leading the system to be weaker from the cyber security point of view: new devices can be used to exploit system vulnerabilities with malicious intentions. In this paper the effect of a cyber-attack in a modern all-electric ship Integrated Power System is investigated and an alternative paradigm is exploited with a view to enhancing the system security and reliability. The need for security by design has become crucial but it is not enough to prevent all the cyber-attacks and so the dependability theory approach is considered in order to avoid the undesired system failures.

This paper focuses on a possible evolution of the control architectures suitable for Integrated P... more This paper focuses on a possible evolution of the control architectures suitable for Integrated Power Systems in modern all-electric ships. In control systems there is a major trend in using information and telecommunication technology as general real-time operating systems and standard communication protocols. This trend leads a standardization at software and communication protocol level that is unavoidable considering the ever-increasing needs of integration of power electronics and control systems in shipboard Integrated Power Systems. Using Internet of Things protocol frameworks can improve quality and performance of controlled systems.

ABSTRACT Power quality is a key issue in islanded electric power systems. Considering the intrins... more ABSTRACT Power quality is a key issue in islanded electric power systems. Considering the intrinsic weakness of islanded grids, this paramount aspect is not of easy accomplishment. To fulfill power quality requirements in these weak electric systems, high performance voltage and frequency controls are needed, although the interactions between these controls can lead to stability issues. In particular, frequency and voltage controls' bandwidth overlapping may produce destabilizing actions. In this paper, a study of the electromechanical stability in shipboard integrated power systems is presented, with particular reference to the case in which voltage and frequency controls dynamically interact.

2014 International Conference on Renewable Energy Research and Application (ICRERA), Oct 1, 2014

Distributed Generation (DG) operating in a distribution network influences active power losses. I... more Distributed Generation (DG) operating in a distribution network influences active power losses. In this paper power losses have been estimated for an actual low voltage distribution network and compared for different situations according to the DG penetration and placement of the power units. A practical method to place new DGs is presented. The basic idea is to minimize power losses, while complying voltage network limits, calculated with power flows using historical data over a discrete number of possible points of connection.

This paper describes the design of the revamping of a hydro power plant and the starting method o... more This paper describes the design of the revamping of a hydro power plant and the starting method of its pump unit. Due to economical and technical constraints, it has been decided to use a synchronous machine with a direct connection to a synchronous generator. After the modeling of the power plant, it has been decided to start the synchronous motor asynchronously and then to synchronize it with the generator. Simulation of the possible starting sequence has been carried out and will be presented.

We calculate the historical payback time (PBT) and internal rate of return (IRR) for domestic pho... more We calculate the historical payback time (PBT) and internal rate of return (IRR) for domestic photovoltaic systems installed at different times between 2003 and 2014, in three different Italian locations (North, center, South, thus representing different levels of energy yield). We show that over time, even though rather different regimes of governmental incentivization and end-user energy prices existed, such economic parameters have hardly been affected. Remarkably, this is true even for the case of systems installed in 2014 - i.e. where no incentivization of any kind is considered, but grid parity has been attained. In this case the PBT is 10.6, 9.3, 8.5 years for the locations in the North, center, and South, respectively; the IRR is 9.1%, 10.4%, 11.3%, respectively. These observations are in marked contrast with the common understanding that the dramatic reduction of installations in Italy after 2011 is due to a reduction of the economic convenience for the end-user, suggesting that the economic factor only plays a marginal role in current PV market dynamics.

IEEE Transactions on Transportation Electrification, 2023

Institution of Engineering and Technology eBooks, Sep 15, 2022

The synchronous generators’ excitation is usually regulated by means of a real-time digital contr... more The synchronous generators’ excitation is usually regulated by means of a real-time digital control system, while other apparatuses are dedicated to secondary functions (e.g human machine interface, remote control unit, logic and control functions). A performance increase and a cost reduction can be achieved by integrating all the functions into a single platform. However, this requires assessing the dependability performance of the control systems currently in use, to set a base benchmark for future evaluations. In this paper, the quantitative dependability analysis of a digital excitation control system is performed, by using as a case study a real system installed in a hydroelectric power station. Two configurations are analyzed, and their dependability performance are compared.