This paper considers the enhancement of loss-of-mains detection by use of a differential rate-of-... more This paper considers the enhancement of loss-of-mains detection by use of a differential rate-of-change-of-frequency relay to reduce nuisance tripping and improve sensitivity to small excursions in frequency. The telecommunications media which might carry the differential ROCOF signal are reviewed with a focus on channel latency, bandwidth and security.
2013 48th International Universities' Power Engineering Conference (UPEC), 2013
ABSTRACT This paper presents a case of photovoltaic system applying stabilizers in a 16-machine p... more ABSTRACT This paper presents a case of photovoltaic system applying stabilizers in a 16-machine power system to alleviate inter-area power oscillations. As PV power station can exchange both active and reactive power with power grid, stabilizers attached to a PV system is able to function to suppress power system oscillations via regulation of active or/and reactive power. Thus PV system based stabilizers can be classified into two types, active stabilizer and reactive stabilizer. In the paper, firstly mathematical model of PV power station installed in a multi-machine power system is described. The damping function of stabilizers attached to the PV system is analyzed. Then a case of applying PV generation stabilizers in multi-machine power system is presented. Both the active and reactive stabilizer attached to the PV system is designed and their performance to suppress inter-area power oscillations is compared.
This paper summarizes a new concept to determine principal curves for nonlinear principal compone... more This paper summarizes a new concept to determine principal curves for nonlinear principal component analysis (PCA). The concept is explained within the framework of the Hastie and Stuetzle algorithm and utilizes spline functions. The paper proposes a new algorithm and shows that it provides an efficient method to extract underlying information from measured data. The new method is geometrically simple and computationally expedient, as the number of unknown parameters increases linearly with the analyzed variable set. The utility of the algorithm is exemplified in two examples.
... Proceedings of the 2010 international conference on Life system modeling and simulation and .... more ... Proceedings of the 2010 international conference on Life system modeling and simulation and ... Then the concept and inference of dynamic Bayesian networks (DBN) are introduced, and SA ... of typhoon cloud images, especially the feature of gray level distribution of typhoon ...
2007 42nd International Universities Power Engineering Conference, 2007
... 1. Y. He, J. Hu and Z. Rende, “Modelling and Control of Wind-Turbine Used DFIG Under Network ... more ... 1. Y. He, J. Hu and Z. Rende, “Modelling and Control of Wind-Turbine Used DFIG Under Network Fault Conditions” Proceedings of the Eighth International Conf. ... 3. R. Cardenas, R. Pena, M. Perez, J. Clare, G. Asher, and P. Wheeler, “Control of a Switched Reluctance ...
2008 43rd International Universities Power Engineering Conference, 2008
ABSTRACT This paper studies the impact of tower shadow effect on the power output of a fixed-spee... more ABSTRACT This paper studies the impact of tower shadow effect on the power output of a fixed-speed wind farm. A data acquisition unit was placed at a wind farm in Northern Ireland which consists of ten fixed-speed wind turbines. The recording equipment logged the wind farmpsilas electrical data, which was time stamped using the global positioning network. Video footage of the wind farm was recorded and from it the blade angle of each turbine was determined with respect to time. Using the blade angle data and the wind farmpsilas power output, studies where performed to ascertain the extent of tower shadow effect on power fluctuation. This paper presents evidence that suggests that tower shadow effect has a significant impact on power fluctuation and that this effect is increased due to the synchronising of turbine blades around the tower region.
Proceedings of the 17th IFAC World Congress, 2008, 2008
ABSTRACT This paper proposes a fast moving window algorithm for QR and Cholesky decompositions by... more ABSTRACT This paper proposes a fast moving window algorithm for QR and Cholesky decompositions by simultaneously applying data updating and downdating. The developed procedure is based on inner products and entails a similar downdating to that of the Chambers' approach. For adding and deleting one row of data from the original matrix, a detailed analysis shows that the proposed algorithm outperforms existing ones in terms or computational efficiency, if the number of columns exceeds 7. For a large number of columns, the proposed algorithm is numerically superior compared to the traditional sequential technique.
ABSTRACT While load flow conditions vary with different loads, the small-signal stability of the ... more ABSTRACT While load flow conditions vary with different loads, the small-signal stability of the entire system is closely related with the locations, capacities and models of loads. In this paper, load impacts with different capacities and models on the small-signal stability are analysed. In the real large-scale power system case, the load sensitivity which denotes the sensitivity of the eigenvalue with respect to the load active power is introduced and applied to rank the loads. The loads with high sensitivity are also considered.
ABSTRACT In July 2010, the Shanghai Donghai Bridge wind farm, the first commercial offshore wind ... more ABSTRACT In July 2010, the Shanghai Donghai Bridge wind farm, the first commercial offshore wind project was connected to the main grid in China. Three months later, four contracts were handed out to build a total of 1GW wind power capacity in the first round of an offshore concession project by the Chinese central government. At that time, there was a worldwide expectation that Chinese offshore wind power capacity would expand rapidly. However, China only achieved a total offshore wind power installed capacity of 389.2 MW by the end of 2012. This paper studies the resent development of offshore wind power in China by dividing China's offshore wind power projects into three categories. This paper presents the difficulties for the Chinese government to achieve its 12th Five Year Plan for offshore wind power. Some policy recommendations to overcome the current difficulties are made in the conclusions.
ABSTRACT A micro-grid is an autonomous system which can be operated while connected to an externa... more ABSTRACT A micro-grid is an autonomous system which can be operated while connected to an external system or isolated with the help of energy storage systems (ESSs). While the daily output of distributed generators (DGs) strongly depends on the temporal distribution of natural resources such as wind and solar, unregulated electric vehicle (EV) charging demand will reduce the imbalance between the daily load and generation curves. In this paper, a statistical model is presented to describe daily EV charging/discharging behaviour. An optimisation problem is proposed and verified to obtain economic operation for the micro-grid based on this model. In day-ahead scheduling, with estimated information of power generation and load demand, optimal charging/discharging of EVs during 24 hours is obtained. A series of numerical optimisation solutions, in different scenarios, is achieved by serial quadratic programming. The results show that with optimal charging/discharging of EVs network losses can be decreased.
ABSTRACT This paper presents the application of decomposed analysis of damping contribution from ... more ABSTRACT This paper presents the application of decomposed analysis of damping contribution from a PSS installed in a real large scale Chinese power system. With the decomposition of damping function from the PSS into damping torque contribution and its connections with the power system oscillation mode of interests, a deep understanding on the PSS function is obtained in the complex large scale multi-machine power system. In the paper, the mathematical description of decomposed analysis of damping contribution from the PSS is firstly given. Then the result of application in real large-scale Chinese power system is presented.
ABSTRACT This paper presents a case of applying STATCOM/BESS (battery energy storage system) stab... more ABSTRACT This paper presents a case of applying STATCOM/BESS (battery energy storage system) stabilizers in a real large scale Chinese power system to alleviate inter-area power oscillations. As STATCOM/BESS can exchange both active and reactive power with power grid, stabilizers attached to a STATCOM/BESS is able to function to suppress power system oscillations via regulation of active or/and reactive power. Thus STATCOM/BESS stabilizers can be classified into two types, active stabilizer and reactive stabilizer. In the paper, firstly mathematical model of STATCOM/BESS installed in a multi-machine power system is described. The damping function of stabilizers attached to the STATCOM/BESS is analysed. Then a case of applying STATCOM/BESS stabilizers in a real large-scale Chinese power system is presented. Both the STATCOM/BESS active and reactive stabilizer is designed and their performance to suppress inter-area power oscillations is compared.
ABSTRACT This paper presents a study case of applying PMU jointly with PSS design in a real large... more ABSTRACT This paper presents a study case of applying PMU jointly with PSS design in a real large scale Chinese power system to suppress inter-area power oscillations. The application uses PMU measured feedback signals to design a PSS by using the technique of the damping torque analysis (DTA). In the paper, a mathematical model of multi-machine power system is described firstly, followed by formulation of the residue and DTA indices. This provides the basis of selecting PMU measured feedback signals and location of PSS to achieve the best result of damping power system inter-area oscillations. Simulation results of applying the method presented in the paper in a real large-scale Chinese power system demonstrate the effectiveness of the coordinated design of PMU and PSS to suppress inter-area power oscillations.
ABSTRACT This paper investigates the use of plug-in parking lots (SmartPark) as integral energy s... more ABSTRACT This paper investigates the use of plug-in parking lots (SmartPark) as integral energy storage to improve small-signal stability using plug-in electric vehicles (PEVs). The paper establishes the Phillips-Heffron model of a power system for a SmartPark solution. Based on this model, SmartPark-based stabilisers have been designed based using phase compensation to improve power system oscillation stability. The effectiveness of stabilisation superimposed on the active and reactive power regulators is verified by simulations obtained from a multi-machine power system model with SmartPark and a large-scale wind farm inclusion.
This paper considers the enhancement of loss-of-mains detection by use of a differential rate-of-... more This paper considers the enhancement of loss-of-mains detection by use of a differential rate-of-change-of-frequency relay to reduce nuisance tripping and improve sensitivity to small excursions in frequency. The telecommunications media which might carry the differential ROCOF signal are reviewed with a focus on channel latency, bandwidth and security.
2013 48th International Universities' Power Engineering Conference (UPEC), 2013
ABSTRACT This paper presents a case of photovoltaic system applying stabilizers in a 16-machine p... more ABSTRACT This paper presents a case of photovoltaic system applying stabilizers in a 16-machine power system to alleviate inter-area power oscillations. As PV power station can exchange both active and reactive power with power grid, stabilizers attached to a PV system is able to function to suppress power system oscillations via regulation of active or/and reactive power. Thus PV system based stabilizers can be classified into two types, active stabilizer and reactive stabilizer. In the paper, firstly mathematical model of PV power station installed in a multi-machine power system is described. The damping function of stabilizers attached to the PV system is analyzed. Then a case of applying PV generation stabilizers in multi-machine power system is presented. Both the active and reactive stabilizer attached to the PV system is designed and their performance to suppress inter-area power oscillations is compared.
This paper summarizes a new concept to determine principal curves for nonlinear principal compone... more This paper summarizes a new concept to determine principal curves for nonlinear principal component analysis (PCA). The concept is explained within the framework of the Hastie and Stuetzle algorithm and utilizes spline functions. The paper proposes a new algorithm and shows that it provides an efficient method to extract underlying information from measured data. The new method is geometrically simple and computationally expedient, as the number of unknown parameters increases linearly with the analyzed variable set. The utility of the algorithm is exemplified in two examples.
... Proceedings of the 2010 international conference on Life system modeling and simulation and .... more ... Proceedings of the 2010 international conference on Life system modeling and simulation and ... Then the concept and inference of dynamic Bayesian networks (DBN) are introduced, and SA ... of typhoon cloud images, especially the feature of gray level distribution of typhoon ...
2007 42nd International Universities Power Engineering Conference, 2007
... 1. Y. He, J. Hu and Z. Rende, “Modelling and Control of Wind-Turbine Used DFIG Under Network ... more ... 1. Y. He, J. Hu and Z. Rende, “Modelling and Control of Wind-Turbine Used DFIG Under Network Fault Conditions” Proceedings of the Eighth International Conf. ... 3. R. Cardenas, R. Pena, M. Perez, J. Clare, G. Asher, and P. Wheeler, “Control of a Switched Reluctance ...
2008 43rd International Universities Power Engineering Conference, 2008
ABSTRACT This paper studies the impact of tower shadow effect on the power output of a fixed-spee... more ABSTRACT This paper studies the impact of tower shadow effect on the power output of a fixed-speed wind farm. A data acquisition unit was placed at a wind farm in Northern Ireland which consists of ten fixed-speed wind turbines. The recording equipment logged the wind farmpsilas electrical data, which was time stamped using the global positioning network. Video footage of the wind farm was recorded and from it the blade angle of each turbine was determined with respect to time. Using the blade angle data and the wind farmpsilas power output, studies where performed to ascertain the extent of tower shadow effect on power fluctuation. This paper presents evidence that suggests that tower shadow effect has a significant impact on power fluctuation and that this effect is increased due to the synchronising of turbine blades around the tower region.
Proceedings of the 17th IFAC World Congress, 2008, 2008
ABSTRACT This paper proposes a fast moving window algorithm for QR and Cholesky decompositions by... more ABSTRACT This paper proposes a fast moving window algorithm for QR and Cholesky decompositions by simultaneously applying data updating and downdating. The developed procedure is based on inner products and entails a similar downdating to that of the Chambers' approach. For adding and deleting one row of data from the original matrix, a detailed analysis shows that the proposed algorithm outperforms existing ones in terms or computational efficiency, if the number of columns exceeds 7. For a large number of columns, the proposed algorithm is numerically superior compared to the traditional sequential technique.
ABSTRACT While load flow conditions vary with different loads, the small-signal stability of the ... more ABSTRACT While load flow conditions vary with different loads, the small-signal stability of the entire system is closely related with the locations, capacities and models of loads. In this paper, load impacts with different capacities and models on the small-signal stability are analysed. In the real large-scale power system case, the load sensitivity which denotes the sensitivity of the eigenvalue with respect to the load active power is introduced and applied to rank the loads. The loads with high sensitivity are also considered.
ABSTRACT In July 2010, the Shanghai Donghai Bridge wind farm, the first commercial offshore wind ... more ABSTRACT In July 2010, the Shanghai Donghai Bridge wind farm, the first commercial offshore wind project was connected to the main grid in China. Three months later, four contracts were handed out to build a total of 1GW wind power capacity in the first round of an offshore concession project by the Chinese central government. At that time, there was a worldwide expectation that Chinese offshore wind power capacity would expand rapidly. However, China only achieved a total offshore wind power installed capacity of 389.2 MW by the end of 2012. This paper studies the resent development of offshore wind power in China by dividing China's offshore wind power projects into three categories. This paper presents the difficulties for the Chinese government to achieve its 12th Five Year Plan for offshore wind power. Some policy recommendations to overcome the current difficulties are made in the conclusions.
ABSTRACT A micro-grid is an autonomous system which can be operated while connected to an externa... more ABSTRACT A micro-grid is an autonomous system which can be operated while connected to an external system or isolated with the help of energy storage systems (ESSs). While the daily output of distributed generators (DGs) strongly depends on the temporal distribution of natural resources such as wind and solar, unregulated electric vehicle (EV) charging demand will reduce the imbalance between the daily load and generation curves. In this paper, a statistical model is presented to describe daily EV charging/discharging behaviour. An optimisation problem is proposed and verified to obtain economic operation for the micro-grid based on this model. In day-ahead scheduling, with estimated information of power generation and load demand, optimal charging/discharging of EVs during 24 hours is obtained. A series of numerical optimisation solutions, in different scenarios, is achieved by serial quadratic programming. The results show that with optimal charging/discharging of EVs network losses can be decreased.
ABSTRACT This paper presents the application of decomposed analysis of damping contribution from ... more ABSTRACT This paper presents the application of decomposed analysis of damping contribution from a PSS installed in a real large scale Chinese power system. With the decomposition of damping function from the PSS into damping torque contribution and its connections with the power system oscillation mode of interests, a deep understanding on the PSS function is obtained in the complex large scale multi-machine power system. In the paper, the mathematical description of decomposed analysis of damping contribution from the PSS is firstly given. Then the result of application in real large-scale Chinese power system is presented.
ABSTRACT This paper presents a case of applying STATCOM/BESS (battery energy storage system) stab... more ABSTRACT This paper presents a case of applying STATCOM/BESS (battery energy storage system) stabilizers in a real large scale Chinese power system to alleviate inter-area power oscillations. As STATCOM/BESS can exchange both active and reactive power with power grid, stabilizers attached to a STATCOM/BESS is able to function to suppress power system oscillations via regulation of active or/and reactive power. Thus STATCOM/BESS stabilizers can be classified into two types, active stabilizer and reactive stabilizer. In the paper, firstly mathematical model of STATCOM/BESS installed in a multi-machine power system is described. The damping function of stabilizers attached to the STATCOM/BESS is analysed. Then a case of applying STATCOM/BESS stabilizers in a real large-scale Chinese power system is presented. Both the STATCOM/BESS active and reactive stabilizer is designed and their performance to suppress inter-area power oscillations is compared.
ABSTRACT This paper presents a study case of applying PMU jointly with PSS design in a real large... more ABSTRACT This paper presents a study case of applying PMU jointly with PSS design in a real large scale Chinese power system to suppress inter-area power oscillations. The application uses PMU measured feedback signals to design a PSS by using the technique of the damping torque analysis (DTA). In the paper, a mathematical model of multi-machine power system is described firstly, followed by formulation of the residue and DTA indices. This provides the basis of selecting PMU measured feedback signals and location of PSS to achieve the best result of damping power system inter-area oscillations. Simulation results of applying the method presented in the paper in a real large-scale Chinese power system demonstrate the effectiveness of the coordinated design of PMU and PSS to suppress inter-area power oscillations.
ABSTRACT This paper investigates the use of plug-in parking lots (SmartPark) as integral energy s... more ABSTRACT This paper investigates the use of plug-in parking lots (SmartPark) as integral energy storage to improve small-signal stability using plug-in electric vehicles (PEVs). The paper establishes the Phillips-Heffron model of a power system for a SmartPark solution. Based on this model, SmartPark-based stabilisers have been designed based using phase compensation to improve power system oscillation stability. The effectiveness of stabilisation superimposed on the active and reactive power regulators is verified by simulations obtained from a multi-machine power system model with SmartPark and a large-scale wind farm inclusion.
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Papers by Tim Littler