Cong Nguyen | Can Tho University of Medicine and Pharmacy (original) (raw)
Papers by Cong Nguyen
The complexity of power systems has increased in recent years due to the operation of existing tr... more The complexity of power systems has increased in recent years due to the operation of existing transmission lines closer to their limits using flexible AC transmission system devices (FACTS), and also due to the increased penetration of new types of generators that have more intermittent characteristics and lower inertial response, such as wind generators. This changing nature of power systems has considerable effect on its dynamic behaviour resulting in power swings, dynamic interactions between different power system devices and less synchronized coupling. This paper analyses this changing nature of power systems and their dynamic behaviours to identify critical issues that limit the large-scale integration of wind generators and FACTS devices. The studies in this paper are conducted on the New England and New York power system model. Modal analysis, PV analysis, eigenvalue tracking and dynamic simulations are used to investigate the dynamic behaviour of a complex power system under both small and large disturbances. From the analyses, it can be concluded that the modes related to operating slip and shaft stiffness are critical as they may limit the large-scale integration of wind generation.
Journal of Physics D-applied Physics, 2009
Distributed Generation is increasing in nowadays power systems. Small scale systems such as photo... more Distributed Generation is increasing in nowadays power systems. Small scale systems such as photovoltaic, biomass or small cogeneration plants are connected to the distribution level, while large wind farms will be connected to the transmission level. Both trends lead to a replacement of large synchronous generators as the dominating generation technology. Up to now, transient stability of transmission systems has been analysed to a satisfactory degree of accuracy with a simplified representation of the distribution systems. In future, distributed generation will more and more influence the behaviour of the system. Stiff, inverter-based local generation technologies may improve the system stability; however, increasing electrical distances between large synchronous generators in operation will impede the system stability. These (and other) diverging effects have to be studied in detail. This overview paper summarises the latest findings and reveals future research questions. It is concluded that the accuracy and validity of the currently applied dynamic models for transient stability analysis of power systems with high penetration of DG should be further investigated.
As the issues on market deregulation and renewable energy utilization are gaining significance, d... more As the issues on market deregulation and renewable energy utilization are gaining significance, distributed generators are planned and installed in distribution systems to supply consumers directly. The distribution system is, therefore facing new challenges on its dynamic behavior with the addition of new dynamic devices. This paper investigates the small signal stability of renewable energy based distribution system. The distribution system is fed by synchronous, induction and static generators. The voltage controlled and power factor controlled operations of the synchronous generator are also considered. The results showed that wind generator dynamics are very significant in the system oscillations. The solar PV generator improves the small signal behavior of the system. The impact of penetration of renewable energy resources on a system is demonstrated through eigenvalue analyses. The eigenvalue results are corroborated with the help of time domain analysis.
IEEE Transactions on Power Systems, 2010
Rising wind generation penetrations and the distinctive inertial characteristics of associated tu... more Rising wind generation penetrations and the distinctive inertial characteristics of associated turbine technology will impact system frequency control. While wind production will displace conventional synchronous plant, empirical study data presented also suggest that the relationship between the total stored turbine kinetic energy and the total system power production for wind is a variable that exhibits significant nonlinearity. Changing trends in system frequency behavior of a power system following the loss of the largest generator are studied in detail here, using simplified frequency control models and extensive simulations of wind penetration scenarios over an extended multiyear timeframe. The system frequency response is characterized by the rate of change of frequency and the frequency nadir. Results show that increasing levels of doubly fed induction generators and high-voltage dc interconnection alter the frequency behavior significantly, and that system operators may have to be proactive in developing solutions to meet these challenges.
Environmental concerns over the use of fossil fuels as energy sources for electric power generati... more Environmental concerns over the use of fossil fuels as energy sources for electric power generation have resulted in the rapid increase in the amount of wind-generated power connected to electrical power networks worldwide. As such, the inclusion of accurate wind turbine generator models in power system simulation software has become increasingly important. Steady-state and dynamic models of wind turbine generators are required for different types of simulation studies. Steady-state fixed-speed and variable-speed models are examined in this paper in terms of their effect on the power flow convergence, voltage stability limits, and their ability to be used to provide good initial values in dynamic models.
This paper presents the application of FACTS devices for the enhancement of dynamic voltage stabi... more This paper presents the application of FACTS devices for the enhancement of dynamic voltage stability in distribution networks with distributed wind generation. The analysis is carried over a test distribution system representative of the Kumamoto area in Japan. The detailed mathematical modelling of the system is also presented. Firstly, this paper provides simulation results showing the effects of higher and lower penetration of distributed wind generation on the voltage dynamics in a faulted system. Then, a distribution static synchronous compensator (D-STATCOM) is used to improve the voltage profile of the system. This analysis shows that D-STATCOM has significant performance to improve the voltage dynamics of distribution system compared to shunt capacitor.
When large renewable energy sources (RES) are integrated into a power system, the dynamics and th... more When large renewable energy sources (RES) are integrated into a power system, the dynamics and the operation of the network are affected. This paper studies the effect of variation in wind speed when a large wind power is integrated into the power system using fixed speed squirrel cage induction generator (SCIG). The wind farm is modelled with the commercially available
The complexity of power systems has increased in recent years due to the operation of existing tr... more The complexity of power systems has increased in recent years due to the operation of existing transmission lines closer to their limits using flexible AC transmission system devices (FACTS), and also due to the increased penetration of new types of generators that have more intermittent characteristics and lower inertial response, such as wind generators. This changing nature of power systems has considerable effect on its dynamic behaviour resulting in power swings, dynamic interactions between different power system devices and less synchronized coupling. This paper analyses this changing nature of power systems and their dynamic behaviours to identify critical issues that limit the large-scale integration of wind generators and FACTS devices. The studies in this paper are conducted on the New England and New York power system model. Modal analysis, PV analysis, eigenvalue tracking and dynamic simulations are used to investigate the dynamic behaviour of a complex power system under both small and large disturbances. From the analyses, it can be concluded that the modes related to operating slip and shaft stiffness are critical as they may limit the large-scale integration of wind generation.
Journal of Physics D-applied Physics, 2009
Distributed Generation is increasing in nowadays power systems. Small scale systems such as photo... more Distributed Generation is increasing in nowadays power systems. Small scale systems such as photovoltaic, biomass or small cogeneration plants are connected to the distribution level, while large wind farms will be connected to the transmission level. Both trends lead to a replacement of large synchronous generators as the dominating generation technology. Up to now, transient stability of transmission systems has been analysed to a satisfactory degree of accuracy with a simplified representation of the distribution systems. In future, distributed generation will more and more influence the behaviour of the system. Stiff, inverter-based local generation technologies may improve the system stability; however, increasing electrical distances between large synchronous generators in operation will impede the system stability. These (and other) diverging effects have to be studied in detail. This overview paper summarises the latest findings and reveals future research questions. It is concluded that the accuracy and validity of the currently applied dynamic models for transient stability analysis of power systems with high penetration of DG should be further investigated.
As the issues on market deregulation and renewable energy utilization are gaining significance, d... more As the issues on market deregulation and renewable energy utilization are gaining significance, distributed generators are planned and installed in distribution systems to supply consumers directly. The distribution system is, therefore facing new challenges on its dynamic behavior with the addition of new dynamic devices. This paper investigates the small signal stability of renewable energy based distribution system. The distribution system is fed by synchronous, induction and static generators. The voltage controlled and power factor controlled operations of the synchronous generator are also considered. The results showed that wind generator dynamics are very significant in the system oscillations. The solar PV generator improves the small signal behavior of the system. The impact of penetration of renewable energy resources on a system is demonstrated through eigenvalue analyses. The eigenvalue results are corroborated with the help of time domain analysis.
IEEE Transactions on Power Systems, 2010
Rising wind generation penetrations and the distinctive inertial characteristics of associated tu... more Rising wind generation penetrations and the distinctive inertial characteristics of associated turbine technology will impact system frequency control. While wind production will displace conventional synchronous plant, empirical study data presented also suggest that the relationship between the total stored turbine kinetic energy and the total system power production for wind is a variable that exhibits significant nonlinearity. Changing trends in system frequency behavior of a power system following the loss of the largest generator are studied in detail here, using simplified frequency control models and extensive simulations of wind penetration scenarios over an extended multiyear timeframe. The system frequency response is characterized by the rate of change of frequency and the frequency nadir. Results show that increasing levels of doubly fed induction generators and high-voltage dc interconnection alter the frequency behavior significantly, and that system operators may have to be proactive in developing solutions to meet these challenges.
Environmental concerns over the use of fossil fuels as energy sources for electric power generati... more Environmental concerns over the use of fossil fuels as energy sources for electric power generation have resulted in the rapid increase in the amount of wind-generated power connected to electrical power networks worldwide. As such, the inclusion of accurate wind turbine generator models in power system simulation software has become increasingly important. Steady-state and dynamic models of wind turbine generators are required for different types of simulation studies. Steady-state fixed-speed and variable-speed models are examined in this paper in terms of their effect on the power flow convergence, voltage stability limits, and their ability to be used to provide good initial values in dynamic models.
This paper presents the application of FACTS devices for the enhancement of dynamic voltage stabi... more This paper presents the application of FACTS devices for the enhancement of dynamic voltage stability in distribution networks with distributed wind generation. The analysis is carried over a test distribution system representative of the Kumamoto area in Japan. The detailed mathematical modelling of the system is also presented. Firstly, this paper provides simulation results showing the effects of higher and lower penetration of distributed wind generation on the voltage dynamics in a faulted system. Then, a distribution static synchronous compensator (D-STATCOM) is used to improve the voltage profile of the system. This analysis shows that D-STATCOM has significant performance to improve the voltage dynamics of distribution system compared to shunt capacitor.
When large renewable energy sources (RES) are integrated into a power system, the dynamics and th... more When large renewable energy sources (RES) are integrated into a power system, the dynamics and the operation of the network are affected. This paper studies the effect of variation in wind speed when a large wind power is integrated into the power system using fixed speed squirrel cage induction generator (SCIG). The wind farm is modelled with the commercially available