IEEE PECON 2012 held in Kota Kinabalu, Malaysia, 2012
Modeling tools are useful for educational and industrial use. Such tools help the new engineers t... more Modeling tools are useful for educational and industrial use. Such tools help the new engineers to simulate the power system under normal and faulted conditions. This paper presents the design and various data conversion steps of a digital frequency relay. The designed relay will cover both over and under frequency conditions. The digital relay has superiority over electromechanical relay in terms of accuracy and speed. The large frequency variations could lead to complete power system blackout. History has seen several blackouts due to frequency instability, either due to supply-demand unbalance or N-1 contingency. After distributed generation and the possible islanding issues, frequency relay has again gain the attention of the researchers and industrialists. The performance of proposed digital frequency relay will be observed under different system dynamics on MATLAB/SIMULINK®.
Power and Energy (PECon), 2012 IEEE International Conference on
Modeling tools are useful for educational and industrial use. Such tools help the new engineers t... more Modeling tools are useful for educational and industrial use. Such tools help the new engineers to simulate the power system under normal and faulted conditions. This paper presents the design and various data conversion steps of a digital frequency relay. The designed relay will cover both over and under frequency conditions. The digital relay has superiority over electromechanical relay in terms of accuracy and speed. The large frequency variations could lead to complete power system blackout. History has seen several blackouts due to frequency instability, either due to supply-demand unbalance or N-1 contingency. After distributed generation and the possible islanding issues, frequency relay has again gain the attention of the researchers and industrialists. The performance of proposed digital frequency relay will be observed under different system dynamics on MATLAB/SIMULINK®.
This paper implements the State Space Search Method (SSSM) in polar coordinate form to calculate ... more This paper implements the State Space Search Method (SSSM) in polar coordinate form to calculate low voltage solution and Maximum Loading Point of system in ill conditioned system. SSSM modifies the direction of state variable (buses voltage and phase) by using optimal multiplier in order to converge load flow equations in ill conditioned system. The privilege of SSSM emerges in the keeping dimension of load flow jacobian matrix constant. While another method such as continuation and homotopy methods change the framework of jacobian matrix based on predictor and corrector in term of increasing load demand. Indeed, the calculation process of SSSM is based on standard Newton Raphson load flow method. The validation of SSSM is shown by the testing IEEE test systems of 14 and 30 in well and maximum loading point as ill-conditioned systems.
In islanding mode, system frequency is severely disturbed due to imbalance between generation and... more In islanding mode, system frequency is severely disturbed due to imbalance between generation and load demand resulting in overloading or loss of generation cases. In order to cope with these events, under-frequency load shedding scheme (UFLS) is applied to stabilize the frequency. This paper presents an intelligent under frequency load shedding scheme implemented on mini-hydro operating in islanded mode. The proposed UFLS scheme consists of a fuzzy logic load shedding controller (FLLSC) with load shedding controller module (LSCM). The FLLSC by measuring frequency and rate of change of frequency estimates the amount of load to be shed. The LSCM sheds the load estimated by FLLSC. This scheme is tested for event based and response based cases. The results have shown that proposed load shedding scheme successfully estimates the amount of load to be shed and stabilizes the frequency for these cases.
One of the challenge in islanding operation is to maintain frequency stability when generation is... more One of the challenge in islanding operation is to maintain frequency stability when generation is less than demand. This paper presents a new Under-Frequency Load shedding scheme for an islanded distribution network. The scheme is based on an adaptive and intelligent load shedding techniques. This proposed scheme is able to conserve power system collapse even for large disturbance and events in the system. The proposed scheme is evaluated through simulation in PSCAD/EMTDC software. A distribution network connected with mini-hydro generation in Malaysia is chosen for the test. Various test scenarios show the effectiveness of the proposed load shedding scheme to shed optimum load.
The interconnection of distributed generation (DG) into distribution networks is undergoing a rap... more The interconnection of distributed generation (DG) into distribution networks is undergoing a rapid global expansion. It enhances the system’s reliability, while simultaneously reduces pollution problems related to the generation of electrical power. To fully utilize the benefits of DGs, certain technical issues need to be addressed. One of the most important issues in this context is islanding detection. This paper presents a new islanding detection technique that is suitable for multiple mini-hydro type DG units. The proposed strategy is based on the rate of change of reactive power and load connecting strategy to detect islanding within the system. For a large power mismatch, islanding is detected by rate of change of reactive power only. However, for a close power mismatch, the rate of change of reactive power initiates a load connecting strategy, which in turn alters the load on the distribution network. This load variation in the distribution network causes a variation in the rate of change of reactive power, which is utilized to distinguish islanding and other events. The simulation results show that the proposed strategy is effective in detecting islanding occurrence in a distribution network.
The Step Size of the Newton Raphson Method (SSNRM) is based on the optimal multiplier that is use... more The Step Size of the Newton Raphson Method (SSNRM) is based on the optimal multiplier that is used to determine the Multiple Load Flow Solutions (MLFS) for an ill-conditioned power system. However, the SSNRM is incapable of determining the desirable Low Voltage Solution (LVS) from the MLFS at the Maximum Loading Point (MLP), due to the fact that when the load demand increases, the LVSs moves closer to each other at the MLP. Commonly, the smallest optimal multiplier was used to calculate the LVS at the MLP under this condition. However, this paper proves the fact that using the smallest optimal multiplier to determine the most suitable LVS for the systems having multiple solutions at the MLP will not guarantee a favourable outcome. Therefore, this paper investigates the application of the properties of scalar quadratic equations (PSQE) that enhances the function of the SSNRM at the MLP. Thus, an indicator, based on PSQE, is introduced in this work, which amends the existing SSNRM for the purpose of finding the desirable LVS at the MLP. The closest optimal multiplier to the proposed indicator is selected in order to
determine the desirable LVS from all possible solutions at the MLP. The proposed method has been tested on a three-bus and IEEE 30-bus systems at the MLP for verification purposes. Additionally, the continuation power flow method is also utilized in order to compare it to the proposed method for the IEEE 30-bus
system at the MLP.
This paper presents the estimation model of Inter-Line Power Flow Controller (IPFC) based on inje... more This paper presents the estimation model of Inter-Line Power Flow Controller (IPFC) based on injection model of synchronization voltage source. The linear model of voltage source inverter is used to estimate steady-state operation of Inter-Line Power Flow Controller. The proposed model can keep the capability of IPFC with the acceptable accuracy. The active and reactive power flow at receiving end line could be controlled separately in this proposed model. Furthermore, the proposed model has these abilities to decrease the reactive power flow and control of the
sending bus voltage at the same time. The validation of the proposed method is shown by using two machine systems to estimate suitable approximation of power flow at receiving end line.
When tripping events or overloading cases occur in power system, load shedding scheme operates to... more When tripping events or overloading cases occur in power system, load shedding scheme operates to shed some load and stabilize the frequency. However, amount of load to be shed greatly depends on, how fast governor can utilizeDG spinning reserve. This paper compares the response of DG with fuzzy based governor and PID based governor in utilization of DG spinning reserve. The simulation results show that DG with fuzzy based governor utilizes spinning reserve more quickly and requires lesser load to be shed than a DG with PID based governor.
This paper uses the State Space Search Method (SSSM) in polar coordinate form to obtain low volta... more This paper uses the State Space Search Method (SSSM) in polar coordinate form to obtain low voltage solution and maximum loading point of ill-condition power system. SSSM improves the direction of state variables (buses voltage and phase) of system buses based on optimal multiplier to converge load flow equations in ill-conditioned system. The advantage of SSSM is apparent in constant preservation of dimension of Jacobian matrix in load flow equations. Whereas another approaches such as Homotopy and continuation power flow vary the framework of Jacobian matrix based on predictor and corrector elements during enhancing load demand. The calculation procedure of SSSM is depending on
classical Newton-Raphson load flow method. The reliability of SSSM is indicated by IEEE test systems, 14 and 30 buses in well and ill-conditioned at maximum loading point as systems.
The frequency of power system is very sensitive to load changing when operating in islanded mode.... more The frequency of power system is very sensitive to load changing when operating in islanded mode. This may causes overloading or loss of generation cases. Under-Frequency Load Shedding (UFLS) Scheme is commonly applied to stabilize the frequency during these cases. Conventional UFLS scheme operates successfully in interconnected grid system and may not work
well when applied to DG based system operating in islanded mode. This paper presents a new fuzzy logic based under- frequency load shedding scheme implemented on mini hydro type-DG operating in islanded mode.
The proposed strategy is based on frequency, rate of change of frequency and load prioritization. In proposed UFLS scheme, a fuzzy logic load shedding controller (FLLSC) with Load Shed
Controller Module (LSCM) is modelled. FLLSC measures amount of load to be shed and LSCM shed the respective load to stabilize frequency. The proposed scheme is validated on different
event-based and response-based cases. Simulation results show that proposed scheme is effective in shedding optimal number of loads while stabilizing the frequency.
This paper implements the Optimal Multiplier Load Flow Method (OMLFM) in polar coordinate form to... more This paper implements the Optimal Multiplier Load Flow Method (OMLFM) in polar coordinate form to calculate low voltage
solution and maximum loading point of system in ill conditioned system. OMLFM modifies the direction of state variables (buses voltage and phase) by using optimal multiplier in order to the convergence of load flow equations in ill conditioned system. The privilege of OMLFM emerges in keeping dimension of load flow jacobian matrix constant. While another method such as continuation and homotopy methods change the framework of jacobian matrix based on predictor and corrector steps in term of increasing load demand. Actually, the calculation process of SSSM is based on standard Newton Raphson load flow method. The validation of OMLFM for maximum loading point as ill-conditioned system is shown by testing IEEE 57 bus test system. Furthermore, the 13 bus radial transmission system is tested
to with verify OMLFM for ill conditioned system includes high R/X ratio lines and the weak interconnection.
Under-frequency load shedding is a common technique to maintain the power system stability by rem... more Under-frequency load shedding is a common technique to maintain the power system stability by removing the overload in some part of the system. The existing under-frequency load
shedding schemes operate successfully in the interconnected grid system. A particular approach of under-frequency load shedding scheme is required for an islanded system which is known to be not as strong as the grid. This paper presents a new approach of load shedding scheme in an islanded distribution system incorporating distribution state estimation. The scheme is based on an intelligent technique to reduce the effect of power deficiency in an islanded network. The disturbance magnitude is calculated based on rate of change of frequency by using the simplest expression of the generator swing equation. Moreover, the process for assessing the power consumption of the customer can be achieved by state estimation method. In this paper, state
estimation for a distribution network is developed and enhanced by composite load model to obtain the most practical value of the system state variables. Finally, the calculated value of the disturbance magnitude will be shed according to the estimated value of loads in each bus.
International Journal of Electrical Power and Energy Systems
Under-Frequency Load Shedding (UFLS) is a common technique to maintain power system stability by ... more Under-Frequency Load Shedding (UFLS) is a common technique to maintain power system stability by removing the overload in some part of the system. The existing UFLS schemes operate successfully in the interconnected grid system. A particular approach of UFLS scheme is required for an islanded system which is known to be not as strong as the grid. This paper presents a new approach of UFLS scheme for the implementation in an islanded distribution system. The scheme is based on a combination of adaptive and intelligent techniques. The disturbance magnitude for response based and event based is treated differently: (1) event based is based on the power imbalance and (2) response based is based on the swing equation which relies on the frequency and rate of change of frequency measurement. Dynamic simulation on an intentional islanding operation is performed on an existing Malaysian network interconnected with a mini hydro generation. The objective is to investigate the effectiveness of the proposed scheme. The simulation results demonstrate that the proposed scheme is capable of improving the frequency response of the islanded system. A significant finding is that the scheme can successfully reduce the effect of power deficiency following the grid connected to islanding operation transition.
IEEE PECON 2012 held in Kota Kinabalu, Malaysia, 2012
Modeling tools are useful for educational and industrial use. Such tools help the new engineers t... more Modeling tools are useful for educational and industrial use. Such tools help the new engineers to simulate the power system under normal and faulted conditions. This paper presents the design and various data conversion steps of a digital frequency relay. The designed relay will cover both over and under frequency conditions. The digital relay has superiority over electromechanical relay in terms of accuracy and speed. The large frequency variations could lead to complete power system blackout. History has seen several blackouts due to frequency instability, either due to supply-demand unbalance or N-1 contingency. After distributed generation and the possible islanding issues, frequency relay has again gain the attention of the researchers and industrialists. The performance of proposed digital frequency relay will be observed under different system dynamics on MATLAB/SIMULINK®.
Power and Energy (PECon), 2012 IEEE International Conference on
Modeling tools are useful for educational and industrial use. Such tools help the new engineers t... more Modeling tools are useful for educational and industrial use. Such tools help the new engineers to simulate the power system under normal and faulted conditions. This paper presents the design and various data conversion steps of a digital frequency relay. The designed relay will cover both over and under frequency conditions. The digital relay has superiority over electromechanical relay in terms of accuracy and speed. The large frequency variations could lead to complete power system blackout. History has seen several blackouts due to frequency instability, either due to supply-demand unbalance or N-1 contingency. After distributed generation and the possible islanding issues, frequency relay has again gain the attention of the researchers and industrialists. The performance of proposed digital frequency relay will be observed under different system dynamics on MATLAB/SIMULINK®.
This paper implements the State Space Search Method (SSSM) in polar coordinate form to calculate ... more This paper implements the State Space Search Method (SSSM) in polar coordinate form to calculate low voltage solution and Maximum Loading Point of system in ill conditioned system. SSSM modifies the direction of state variable (buses voltage and phase) by using optimal multiplier in order to converge load flow equations in ill conditioned system. The privilege of SSSM emerges in the keeping dimension of load flow jacobian matrix constant. While another method such as continuation and homotopy methods change the framework of jacobian matrix based on predictor and corrector in term of increasing load demand. Indeed, the calculation process of SSSM is based on standard Newton Raphson load flow method. The validation of SSSM is shown by the testing IEEE test systems of 14 and 30 in well and maximum loading point as ill-conditioned systems.
In islanding mode, system frequency is severely disturbed due to imbalance between generation and... more In islanding mode, system frequency is severely disturbed due to imbalance between generation and load demand resulting in overloading or loss of generation cases. In order to cope with these events, under-frequency load shedding scheme (UFLS) is applied to stabilize the frequency. This paper presents an intelligent under frequency load shedding scheme implemented on mini-hydro operating in islanded mode. The proposed UFLS scheme consists of a fuzzy logic load shedding controller (FLLSC) with load shedding controller module (LSCM). The FLLSC by measuring frequency and rate of change of frequency estimates the amount of load to be shed. The LSCM sheds the load estimated by FLLSC. This scheme is tested for event based and response based cases. The results have shown that proposed load shedding scheme successfully estimates the amount of load to be shed and stabilizes the frequency for these cases.
One of the challenge in islanding operation is to maintain frequency stability when generation is... more One of the challenge in islanding operation is to maintain frequency stability when generation is less than demand. This paper presents a new Under-Frequency Load shedding scheme for an islanded distribution network. The scheme is based on an adaptive and intelligent load shedding techniques. This proposed scheme is able to conserve power system collapse even for large disturbance and events in the system. The proposed scheme is evaluated through simulation in PSCAD/EMTDC software. A distribution network connected with mini-hydro generation in Malaysia is chosen for the test. Various test scenarios show the effectiveness of the proposed load shedding scheme to shed optimum load.
The interconnection of distributed generation (DG) into distribution networks is undergoing a rap... more The interconnection of distributed generation (DG) into distribution networks is undergoing a rapid global expansion. It enhances the system’s reliability, while simultaneously reduces pollution problems related to the generation of electrical power. To fully utilize the benefits of DGs, certain technical issues need to be addressed. One of the most important issues in this context is islanding detection. This paper presents a new islanding detection technique that is suitable for multiple mini-hydro type DG units. The proposed strategy is based on the rate of change of reactive power and load connecting strategy to detect islanding within the system. For a large power mismatch, islanding is detected by rate of change of reactive power only. However, for a close power mismatch, the rate of change of reactive power initiates a load connecting strategy, which in turn alters the load on the distribution network. This load variation in the distribution network causes a variation in the rate of change of reactive power, which is utilized to distinguish islanding and other events. The simulation results show that the proposed strategy is effective in detecting islanding occurrence in a distribution network.
The Step Size of the Newton Raphson Method (SSNRM) is based on the optimal multiplier that is use... more The Step Size of the Newton Raphson Method (SSNRM) is based on the optimal multiplier that is used to determine the Multiple Load Flow Solutions (MLFS) for an ill-conditioned power system. However, the SSNRM is incapable of determining the desirable Low Voltage Solution (LVS) from the MLFS at the Maximum Loading Point (MLP), due to the fact that when the load demand increases, the LVSs moves closer to each other at the MLP. Commonly, the smallest optimal multiplier was used to calculate the LVS at the MLP under this condition. However, this paper proves the fact that using the smallest optimal multiplier to determine the most suitable LVS for the systems having multiple solutions at the MLP will not guarantee a favourable outcome. Therefore, this paper investigates the application of the properties of scalar quadratic equations (PSQE) that enhances the function of the SSNRM at the MLP. Thus, an indicator, based on PSQE, is introduced in this work, which amends the existing SSNRM for the purpose of finding the desirable LVS at the MLP. The closest optimal multiplier to the proposed indicator is selected in order to
determine the desirable LVS from all possible solutions at the MLP. The proposed method has been tested on a three-bus and IEEE 30-bus systems at the MLP for verification purposes. Additionally, the continuation power flow method is also utilized in order to compare it to the proposed method for the IEEE 30-bus
system at the MLP.
This paper presents the estimation model of Inter-Line Power Flow Controller (IPFC) based on inje... more This paper presents the estimation model of Inter-Line Power Flow Controller (IPFC) based on injection model of synchronization voltage source. The linear model of voltage source inverter is used to estimate steady-state operation of Inter-Line Power Flow Controller. The proposed model can keep the capability of IPFC with the acceptable accuracy. The active and reactive power flow at receiving end line could be controlled separately in this proposed model. Furthermore, the proposed model has these abilities to decrease the reactive power flow and control of the
sending bus voltage at the same time. The validation of the proposed method is shown by using two machine systems to estimate suitable approximation of power flow at receiving end line.
When tripping events or overloading cases occur in power system, load shedding scheme operates to... more When tripping events or overloading cases occur in power system, load shedding scheme operates to shed some load and stabilize the frequency. However, amount of load to be shed greatly depends on, how fast governor can utilizeDG spinning reserve. This paper compares the response of DG with fuzzy based governor and PID based governor in utilization of DG spinning reserve. The simulation results show that DG with fuzzy based governor utilizes spinning reserve more quickly and requires lesser load to be shed than a DG with PID based governor.
This paper uses the State Space Search Method (SSSM) in polar coordinate form to obtain low volta... more This paper uses the State Space Search Method (SSSM) in polar coordinate form to obtain low voltage solution and maximum loading point of ill-condition power system. SSSM improves the direction of state variables (buses voltage and phase) of system buses based on optimal multiplier to converge load flow equations in ill-conditioned system. The advantage of SSSM is apparent in constant preservation of dimension of Jacobian matrix in load flow equations. Whereas another approaches such as Homotopy and continuation power flow vary the framework of Jacobian matrix based on predictor and corrector elements during enhancing load demand. The calculation procedure of SSSM is depending on
classical Newton-Raphson load flow method. The reliability of SSSM is indicated by IEEE test systems, 14 and 30 buses in well and ill-conditioned at maximum loading point as systems.
The frequency of power system is very sensitive to load changing when operating in islanded mode.... more The frequency of power system is very sensitive to load changing when operating in islanded mode. This may causes overloading or loss of generation cases. Under-Frequency Load Shedding (UFLS) Scheme is commonly applied to stabilize the frequency during these cases. Conventional UFLS scheme operates successfully in interconnected grid system and may not work
well when applied to DG based system operating in islanded mode. This paper presents a new fuzzy logic based under- frequency load shedding scheme implemented on mini hydro type-DG operating in islanded mode.
The proposed strategy is based on frequency, rate of change of frequency and load prioritization. In proposed UFLS scheme, a fuzzy logic load shedding controller (FLLSC) with Load Shed
Controller Module (LSCM) is modelled. FLLSC measures amount of load to be shed and LSCM shed the respective load to stabilize frequency. The proposed scheme is validated on different
event-based and response-based cases. Simulation results show that proposed scheme is effective in shedding optimal number of loads while stabilizing the frequency.
This paper implements the Optimal Multiplier Load Flow Method (OMLFM) in polar coordinate form to... more This paper implements the Optimal Multiplier Load Flow Method (OMLFM) in polar coordinate form to calculate low voltage
solution and maximum loading point of system in ill conditioned system. OMLFM modifies the direction of state variables (buses voltage and phase) by using optimal multiplier in order to the convergence of load flow equations in ill conditioned system. The privilege of OMLFM emerges in keeping dimension of load flow jacobian matrix constant. While another method such as continuation and homotopy methods change the framework of jacobian matrix based on predictor and corrector steps in term of increasing load demand. Actually, the calculation process of SSSM is based on standard Newton Raphson load flow method. The validation of OMLFM for maximum loading point as ill-conditioned system is shown by testing IEEE 57 bus test system. Furthermore, the 13 bus radial transmission system is tested
to with verify OMLFM for ill conditioned system includes high R/X ratio lines and the weak interconnection.
Under-frequency load shedding is a common technique to maintain the power system stability by rem... more Under-frequency load shedding is a common technique to maintain the power system stability by removing the overload in some part of the system. The existing under-frequency load
shedding schemes operate successfully in the interconnected grid system. A particular approach of under-frequency load shedding scheme is required for an islanded system which is known to be not as strong as the grid. This paper presents a new approach of load shedding scheme in an islanded distribution system incorporating distribution state estimation. The scheme is based on an intelligent technique to reduce the effect of power deficiency in an islanded network. The disturbance magnitude is calculated based on rate of change of frequency by using the simplest expression of the generator swing equation. Moreover, the process for assessing the power consumption of the customer can be achieved by state estimation method. In this paper, state
estimation for a distribution network is developed and enhanced by composite load model to obtain the most practical value of the system state variables. Finally, the calculated value of the disturbance magnitude will be shed according to the estimated value of loads in each bus.
International Journal of Electrical Power and Energy Systems
Under-Frequency Load Shedding (UFLS) is a common technique to maintain power system stability by ... more Under-Frequency Load Shedding (UFLS) is a common technique to maintain power system stability by removing the overload in some part of the system. The existing UFLS schemes operate successfully in the interconnected grid system. A particular approach of UFLS scheme is required for an islanded system which is known to be not as strong as the grid. This paper presents a new approach of UFLS scheme for the implementation in an islanded distribution system. The scheme is based on a combination of adaptive and intelligent techniques. The disturbance magnitude for response based and event based is treated differently: (1) event based is based on the power imbalance and (2) response based is based on the swing equation which relies on the frequency and rate of change of frequency measurement. Dynamic simulation on an intentional islanding operation is performed on an existing Malaysian network interconnected with a mini hydro generation. The objective is to investigate the effectiveness of the proposed scheme. The simulation results demonstrate that the proposed scheme is capable of improving the frequency response of the islanded system. A significant finding is that the scheme can successfully reduce the effect of power deficiency following the grid connected to islanding operation transition.
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Papers by Mazaher Karimi
determine the desirable LVS from all possible solutions at the MLP. The proposed method has been tested on a three-bus and IEEE 30-bus systems at the MLP for verification purposes. Additionally, the continuation power flow method is also utilized in order to compare it to the proposed method for the IEEE 30-bus
system at the MLP.
sending bus voltage at the same time. The validation of the proposed method is shown by using two machine systems to estimate suitable approximation of power flow at receiving end line.
classical Newton-Raphson load flow method. The reliability of SSSM is indicated by IEEE test systems, 14 and 30 buses in well and ill-conditioned at maximum loading point as systems.
well when applied to DG based system operating in islanded mode. This paper presents a new fuzzy logic based under- frequency load shedding scheme implemented on mini hydro type-DG operating in islanded mode.
The proposed strategy is based on frequency, rate of change of frequency and load prioritization. In proposed UFLS scheme, a fuzzy logic load shedding controller (FLLSC) with Load Shed
Controller Module (LSCM) is modelled. FLLSC measures amount of load to be shed and LSCM shed the respective load to stabilize frequency. The proposed scheme is validated on different
event-based and response-based cases. Simulation results show that proposed scheme is effective in shedding optimal number of loads while stabilizing the frequency.
solution and maximum loading point of system in ill conditioned system. OMLFM modifies the direction of state variables (buses voltage and phase) by using optimal multiplier in order to the convergence of load flow equations in ill conditioned system. The privilege of OMLFM emerges in keeping dimension of load flow jacobian matrix constant. While another method such as continuation and homotopy methods change the framework of jacobian matrix based on predictor and corrector steps in term of increasing load demand. Actually, the calculation process of SSSM is based on standard Newton Raphson load flow method. The validation of OMLFM for maximum loading point as ill-conditioned system is shown by testing IEEE 57 bus test system. Furthermore, the 13 bus radial transmission system is tested
to with verify OMLFM for ill conditioned system includes high R/X ratio lines and the weak interconnection.
shedding schemes operate successfully in the interconnected grid system. A particular approach of under-frequency load shedding scheme is required for an islanded system which is known to be not as strong as the grid. This paper presents a new approach of load shedding scheme in an islanded distribution system incorporating distribution state estimation. The scheme is based on an intelligent technique to reduce the effect of power deficiency in an islanded network. The disturbance magnitude is calculated based on rate of change of frequency by using the simplest expression of the generator swing equation. Moreover, the process for assessing the power consumption of the customer can be achieved by state estimation method. In this paper, state
estimation for a distribution network is developed and enhanced by composite load model to obtain the most practical value of the system state variables. Finally, the calculated value of the disturbance magnitude will be shed according to the estimated value of loads in each bus.
determine the desirable LVS from all possible solutions at the MLP. The proposed method has been tested on a three-bus and IEEE 30-bus systems at the MLP for verification purposes. Additionally, the continuation power flow method is also utilized in order to compare it to the proposed method for the IEEE 30-bus
system at the MLP.
sending bus voltage at the same time. The validation of the proposed method is shown by using two machine systems to estimate suitable approximation of power flow at receiving end line.
classical Newton-Raphson load flow method. The reliability of SSSM is indicated by IEEE test systems, 14 and 30 buses in well and ill-conditioned at maximum loading point as systems.
well when applied to DG based system operating in islanded mode. This paper presents a new fuzzy logic based under- frequency load shedding scheme implemented on mini hydro type-DG operating in islanded mode.
The proposed strategy is based on frequency, rate of change of frequency and load prioritization. In proposed UFLS scheme, a fuzzy logic load shedding controller (FLLSC) with Load Shed
Controller Module (LSCM) is modelled. FLLSC measures amount of load to be shed and LSCM shed the respective load to stabilize frequency. The proposed scheme is validated on different
event-based and response-based cases. Simulation results show that proposed scheme is effective in shedding optimal number of loads while stabilizing the frequency.
solution and maximum loading point of system in ill conditioned system. OMLFM modifies the direction of state variables (buses voltage and phase) by using optimal multiplier in order to the convergence of load flow equations in ill conditioned system. The privilege of OMLFM emerges in keeping dimension of load flow jacobian matrix constant. While another method such as continuation and homotopy methods change the framework of jacobian matrix based on predictor and corrector steps in term of increasing load demand. Actually, the calculation process of SSSM is based on standard Newton Raphson load flow method. The validation of OMLFM for maximum loading point as ill-conditioned system is shown by testing IEEE 57 bus test system. Furthermore, the 13 bus radial transmission system is tested
to with verify OMLFM for ill conditioned system includes high R/X ratio lines and the weak interconnection.
shedding schemes operate successfully in the interconnected grid system. A particular approach of under-frequency load shedding scheme is required for an islanded system which is known to be not as strong as the grid. This paper presents a new approach of load shedding scheme in an islanded distribution system incorporating distribution state estimation. The scheme is based on an intelligent technique to reduce the effect of power deficiency in an islanded network. The disturbance magnitude is calculated based on rate of change of frequency by using the simplest expression of the generator swing equation. Moreover, the process for assessing the power consumption of the customer can be achieved by state estimation method. In this paper, state
estimation for a distribution network is developed and enhanced by composite load model to obtain the most practical value of the system state variables. Finally, the calculated value of the disturbance magnitude will be shed according to the estimated value of loads in each bus.