Amr A D E L Mohamed | Cairo University (original) (raw)
Uploads
Papers by Amr A D E L Mohamed
Research Undergraduate, May 4, 2011
Many countries have been employing the Internet proxy for different reasons. At the same time, ac... more Many countries have been employing the Internet proxy for different reasons. At the same time, activities of cyber crime have been on the rise. The research covers an extensive literature review on global definitions and examples of censorship, its effects, as well as perceptions and how they could be manipulated; so the technical aspect is covered in a generalized way and so is the psychological view. This research project helps in exploring and understanding peoples› engagement in bypassing the Internet proxy and ...
International Journal of Electrical Power & Energy Systems , 2019
Energy storage systems can provide a series of benefits to improve the operation flexibility and ... more Energy storage systems can provide a series of benefits to improve the operation flexibility and reliability of electric power systems, but their size and placement in the power system are critical to achieving expected benefits. An optimal ES sizing and siting study is presented in this paper. The formulation considers long-term economic benefits all generation and ES technologies for optimal sizing and siting. Unlike other recent studies, the proposed MILP formulation consider reliability as planning parameter. It also considers different lifetimes of ES and other generation assets, and salvage values to compute the present value of benefits. Both long-term (several years) and short-term (hourly) power demand variation are accounted for optimal sizing generators and ES. The developed formulation provides optimal size, location and investment year (a complete investment plan) for all assets. It is a comprehensive, robust production-grade long-term asset planning formulation. The paper presents a detailed case study conducted with the Ward-Hale 6-Bus test system and IEEE 118-Bus test system. Results show that ES assets can be used to improve system reliability overcome network congestion.
Electrical energy storage (EES) can improve the flexibility and reliability of electric power sys... more Electrical energy storage (EES) can improve the flexibility and reliability of electric power systems. At the same time, they can supply different ancillary services. The profit of the energy storage operation can be maximized by deciding the best level of each service. Merchant-owned facilities require a profit-maximizing formulation for grid-connected energy storage systems with multiple ancillary services. This paper proposes a new linear profit-maximizing formulation for grid-connected merchant-owned energy storage systems operating with multiple ancillary services. All technical characteristics of EES have been modelled, including cycle life loss due to fast charge/discharge and low depth of discharge operations. A piece-wise linear model of an EES converter's capability curve has also been included for reactive power modeling. The model was assessed considering a battery EES, a flywheel EES, and a compressed air EES, with the results demonstrating the benefits of the formulation. From case studies, it is clear that the merchant-owned battery EES and the flywheel EES can generate profits, especially from voltage regulation and frequency regulation services. The case studies prove that the proposed model can be used as an optimal planning and operation tool for any type or size of EES. Index Terms-Energy Storage, Ancillary Markets, Energy Storage Scheduling. I. NOMENCLATURE A. Acronyms DOD Maximum depth of discharge of the EES operation EES Electrical energy storage SOC State of charge of the EES B. Indices Index for denoting sections of the cycle life vs DOD curve q Index for denoting quarters Index for denoting hourly time periods of the year, t = 1 : NT C. Parameters Aq Factor for equally distributing investment cost for all quarters of all years (unitless factor) c 1 , c 2 , c 3 Constants for representing operation and maintenance cost equation (units: /cycle,/cycle, /cycle,/MW, and $ respectively) CEC Cost of energy storage for installing a unit of energy storing capacity ($/MWh) D Per hours self-discharge rate (%) EFF Charge/discharge efficiency (%) Total investment cost ($) KC, KD Constants of NC vs SOC curve (units: cycles/MWh and cycles) Kcc 1 , Kcc 2 Constants of the linearization of the inverter's capability curve (unitless) KFR Energy requirement to supply 1 MW of frequency regulation power (MWh/MW) KRP Energy requirement to supply 1 MW of reserve power (MWh/MW) M A large number to model the constraint Maximum energy storage cycle life (cycles) NS Number of sections of cycle life vs depth of discharge curve (No.) NQ Rated lifetime of the battery (quarters) NT Number of hours in the year (No.) P , P Rated charge/discharge power of the EES converter (MW) Activated reserve power (MW) PS , PS Rated charge/discharge power of the EES storage unit (MW)
Electricity jurisdictions procure generation capacity requirements competitively which maintains ... more Electricity jurisdictions procure generation capacity requirements competitively which maintains investment flows into the electricity system infrastructure. The capacity market auction is one of such competitive capacity procurement methods. It is challenging to consider energy storage (ES) capacity offers in capacity markets due to complex capacity contribution characteristics and lack of explicit mechanisms to integrate them. However, ES capacity can be used to manage the system peak demand. ES can substitute for peaker plants, especially if the demand curve is kurtosis. This paper proposes novel ES capacity contribution formulas and a comprehensive capacity auction model which is designed to consider capacity offers including energy-limited technologies such as ES. After all offers are converted to unforced capacity (UCAP), their energy limitations do not affect bid selection in the market. The proposed novel ES UCAP computation formulas consider power capacity, energy capacity and operational attributes. This paper also presents the results of a case study with three capacity supply offers and a case study based on actual Ontario system data. A detailed sensitivity analysis is also included in the paper to show the validity of the proposed ES UCAP formulas in the auction model. The proposed formulas provide significant benefits in successfully procuring ES capacity offers.
Optimal power flow (OPF) is an important power systems optimization tool. However, due to the inh... more Optimal power flow (OPF) is an important power systems optimization tool. However, due to the inherent nonlinearity of the solution space, OPF methods may yield a local optimal solution, leading to economic loss. For this reason, an OPF remains a major research topic. Changing power balance equations can change the solution space, alter solution time, and create a chance of reaching a better solution. In this paper, a new simple linewise optimal power flow (LWOPF) formulation is proposed using line-wise power balance equations and solved using the successive linear programming (SLP) technique. The study results on nine different test systems, up to a 9 241-bus real power system, show that the proposed method is accurate, provides monotonic convergence, scales well for large systems and is consistently faster, up to twice the speed of MATPOWER and other proven bus-wise SLP approaches to solve the OPF.
Voltage collapse is a phenomenon where voltage collapses at one or more busses due to lack of rea... more Voltage collapse is a phenomenon where voltage collapses at one or more busses due to lack of reactive power characterized by a decrease in voltage with increase in reactive power injection and voltage drop in connected lines due to large power flows. Bus-wise power balance equations, solved using the Newton-Raphson (NR) technique, are widely used to analyze power systems for VC. While bus-wise power balance equations succinctly model a power system, it and its Jacobian do not readily point out the most critical set of lines without additional analysis. In this paper, first, a line-wise set of equations for modeling a power system and its solution method using the NR technique for power flow analysis are proposed. Study results on 6-, 14-, 57-, and 118-bus IEEE systems, a 582-bus real system, 2383-bus Polish power system, and 9241-bus PEGASE system show that the proposed method is accurate, provides monotonic convergence, scales well of large systems, and is consistently faster up to twice the speed of the bus-wise NR method, while using sparse matrices. Second, a line-wise VC index is derived and shown to be directly present in the Jacobian of the line-wise NR method, identifying the susceptible set of lines without additional computation. Usefulness of VC index as an online VC assessment tool is demonstrated for a critical loading condition on test systems.
Voltage stability Optimal power flow Line-wise power flow Voltage collapse index A B S T R A C T ... more Voltage stability Optimal power flow Line-wise power flow Voltage collapse index A B S T R A C T Ensuring the voltage stability of power systems is one of the main goals of operators and researchers. The incorporation of voltage stability with optimal power flow (OPF) has received a great deal of attention in the past few years. The line-wise power flow method is shown to provide a faster solution, up to twice the speed of buswise power balance equations, and has a better solution space due to the use of square of voltage magnitudes. Further, the line voltage collapse index (VCI) developed using the set of line-wise power balance equations is shown to be an accurate voltage stability assessment indicator in the literature. In this paper, two novel linear models of voltage stability incorporation with line-wise optimal power flow are proposed based on the set of line-wise power balance equations and its line voltage collapse index. The difference between the two models is based on the way the VCI is utilized. In the first model, VCIs are employed as a set of voltage stability constraints while in the second model VCIs form the objective function. The two models are solved using successive linear programming (SLP) technique. The study test results on several IEEE benchmark systems demonstrate the effectiveness of the proposed two models in attaining a higher voltage stable system at lower cost. 1. A novel nonlinear VSCOPF formulation based on a set of line-wise power balance equations and LVCI is developed.
Electricity jurisdictions procure generation capacity requirements competitively which maintains ... more Electricity jurisdictions procure generation capacity requirements competitively which maintains investment flows into the electricity system infrastructure. The capacity market auction is one of such competitive capacity procurement methods. It is challenging to consider energy storage (ES) capacity offers in capacity markets due to complex capacity contribution characteristics and lack of explicit mechanisms to integrate them. However, ES capacity can be used to manage the system peak demand. ES can substitute for peaker plants, especially if the demand curve is kurtosis. This paper proposes novel ES capacity contribution formulas and a comprehensive capacity auction model which is designed to consider capacity offers including energy-limited technologies such as ES. After all offers are converted to unforced capacity (UCAP), their energy limitations do not affect bid selection in the market. The proposed novel ES UCAP computation formulas consider power capacity, energy capacity and operational attributes. This paper also presents the results of a case study with three capacity supply offers and a case study based on actual Ontario system data. A detailed sensitivity analysis is also included in the paper to show the validity of the proposed ES UCAP formulas in the auction model. The proposed formulas provide significant benefits in successfully procuring ES capacity offers.
Research Undergraduate, May 4, 2011
Many countries have been employing the Internet proxy for different reasons. At the same time, ac... more Many countries have been employing the Internet proxy for different reasons. At the same time, activities of cyber crime have been on the rise. The research covers an extensive literature review on global definitions and examples of censorship, its effects, as well as perceptions and how they could be manipulated; so the technical aspect is covered in a generalized way and so is the psychological view. This research project helps in exploring and understanding peoples› engagement in bypassing the Internet proxy and ...
International Journal of Electrical Power & Energy Systems , 2019
Energy storage systems can provide a series of benefits to improve the operation flexibility and ... more Energy storage systems can provide a series of benefits to improve the operation flexibility and reliability of electric power systems, but their size and placement in the power system are critical to achieving expected benefits. An optimal ES sizing and siting study is presented in this paper. The formulation considers long-term economic benefits all generation and ES technologies for optimal sizing and siting. Unlike other recent studies, the proposed MILP formulation consider reliability as planning parameter. It also considers different lifetimes of ES and other generation assets, and salvage values to compute the present value of benefits. Both long-term (several years) and short-term (hourly) power demand variation are accounted for optimal sizing generators and ES. The developed formulation provides optimal size, location and investment year (a complete investment plan) for all assets. It is a comprehensive, robust production-grade long-term asset planning formulation. The paper presents a detailed case study conducted with the Ward-Hale 6-Bus test system and IEEE 118-Bus test system. Results show that ES assets can be used to improve system reliability overcome network congestion.
Electrical energy storage (EES) can improve the flexibility and reliability of electric power sys... more Electrical energy storage (EES) can improve the flexibility and reliability of electric power systems. At the same time, they can supply different ancillary services. The profit of the energy storage operation can be maximized by deciding the best level of each service. Merchant-owned facilities require a profit-maximizing formulation for grid-connected energy storage systems with multiple ancillary services. This paper proposes a new linear profit-maximizing formulation for grid-connected merchant-owned energy storage systems operating with multiple ancillary services. All technical characteristics of EES have been modelled, including cycle life loss due to fast charge/discharge and low depth of discharge operations. A piece-wise linear model of an EES converter's capability curve has also been included for reactive power modeling. The model was assessed considering a battery EES, a flywheel EES, and a compressed air EES, with the results demonstrating the benefits of the formulation. From case studies, it is clear that the merchant-owned battery EES and the flywheel EES can generate profits, especially from voltage regulation and frequency regulation services. The case studies prove that the proposed model can be used as an optimal planning and operation tool for any type or size of EES. Index Terms-Energy Storage, Ancillary Markets, Energy Storage Scheduling. I. NOMENCLATURE A. Acronyms DOD Maximum depth of discharge of the EES operation EES Electrical energy storage SOC State of charge of the EES B. Indices Index for denoting sections of the cycle life vs DOD curve q Index for denoting quarters Index for denoting hourly time periods of the year, t = 1 : NT C. Parameters Aq Factor for equally distributing investment cost for all quarters of all years (unitless factor) c 1 , c 2 , c 3 Constants for representing operation and maintenance cost equation (units: /cycle,/cycle, /cycle,/MW, and $ respectively) CEC Cost of energy storage for installing a unit of energy storing capacity ($/MWh) D Per hours self-discharge rate (%) EFF Charge/discharge efficiency (%) Total investment cost ($) KC, KD Constants of NC vs SOC curve (units: cycles/MWh and cycles) Kcc 1 , Kcc 2 Constants of the linearization of the inverter's capability curve (unitless) KFR Energy requirement to supply 1 MW of frequency regulation power (MWh/MW) KRP Energy requirement to supply 1 MW of reserve power (MWh/MW) M A large number to model the constraint Maximum energy storage cycle life (cycles) NS Number of sections of cycle life vs depth of discharge curve (No.) NQ Rated lifetime of the battery (quarters) NT Number of hours in the year (No.) P , P Rated charge/discharge power of the EES converter (MW) Activated reserve power (MW) PS , PS Rated charge/discharge power of the EES storage unit (MW)
Electricity jurisdictions procure generation capacity requirements competitively which maintains ... more Electricity jurisdictions procure generation capacity requirements competitively which maintains investment flows into the electricity system infrastructure. The capacity market auction is one of such competitive capacity procurement methods. It is challenging to consider energy storage (ES) capacity offers in capacity markets due to complex capacity contribution characteristics and lack of explicit mechanisms to integrate them. However, ES capacity can be used to manage the system peak demand. ES can substitute for peaker plants, especially if the demand curve is kurtosis. This paper proposes novel ES capacity contribution formulas and a comprehensive capacity auction model which is designed to consider capacity offers including energy-limited technologies such as ES. After all offers are converted to unforced capacity (UCAP), their energy limitations do not affect bid selection in the market. The proposed novel ES UCAP computation formulas consider power capacity, energy capacity and operational attributes. This paper also presents the results of a case study with three capacity supply offers and a case study based on actual Ontario system data. A detailed sensitivity analysis is also included in the paper to show the validity of the proposed ES UCAP formulas in the auction model. The proposed formulas provide significant benefits in successfully procuring ES capacity offers.
Optimal power flow (OPF) is an important power systems optimization tool. However, due to the inh... more Optimal power flow (OPF) is an important power systems optimization tool. However, due to the inherent nonlinearity of the solution space, OPF methods may yield a local optimal solution, leading to economic loss. For this reason, an OPF remains a major research topic. Changing power balance equations can change the solution space, alter solution time, and create a chance of reaching a better solution. In this paper, a new simple linewise optimal power flow (LWOPF) formulation is proposed using line-wise power balance equations and solved using the successive linear programming (SLP) technique. The study results on nine different test systems, up to a 9 241-bus real power system, show that the proposed method is accurate, provides monotonic convergence, scales well for large systems and is consistently faster, up to twice the speed of MATPOWER and other proven bus-wise SLP approaches to solve the OPF.
Voltage collapse is a phenomenon where voltage collapses at one or more busses due to lack of rea... more Voltage collapse is a phenomenon where voltage collapses at one or more busses due to lack of reactive power characterized by a decrease in voltage with increase in reactive power injection and voltage drop in connected lines due to large power flows. Bus-wise power balance equations, solved using the Newton-Raphson (NR) technique, are widely used to analyze power systems for VC. While bus-wise power balance equations succinctly model a power system, it and its Jacobian do not readily point out the most critical set of lines without additional analysis. In this paper, first, a line-wise set of equations for modeling a power system and its solution method using the NR technique for power flow analysis are proposed. Study results on 6-, 14-, 57-, and 118-bus IEEE systems, a 582-bus real system, 2383-bus Polish power system, and 9241-bus PEGASE system show that the proposed method is accurate, provides monotonic convergence, scales well of large systems, and is consistently faster up to twice the speed of the bus-wise NR method, while using sparse matrices. Second, a line-wise VC index is derived and shown to be directly present in the Jacobian of the line-wise NR method, identifying the susceptible set of lines without additional computation. Usefulness of VC index as an online VC assessment tool is demonstrated for a critical loading condition on test systems.
Voltage stability Optimal power flow Line-wise power flow Voltage collapse index A B S T R A C T ... more Voltage stability Optimal power flow Line-wise power flow Voltage collapse index A B S T R A C T Ensuring the voltage stability of power systems is one of the main goals of operators and researchers. The incorporation of voltage stability with optimal power flow (OPF) has received a great deal of attention in the past few years. The line-wise power flow method is shown to provide a faster solution, up to twice the speed of buswise power balance equations, and has a better solution space due to the use of square of voltage magnitudes. Further, the line voltage collapse index (VCI) developed using the set of line-wise power balance equations is shown to be an accurate voltage stability assessment indicator in the literature. In this paper, two novel linear models of voltage stability incorporation with line-wise optimal power flow are proposed based on the set of line-wise power balance equations and its line voltage collapse index. The difference between the two models is based on the way the VCI is utilized. In the first model, VCIs are employed as a set of voltage stability constraints while in the second model VCIs form the objective function. The two models are solved using successive linear programming (SLP) technique. The study test results on several IEEE benchmark systems demonstrate the effectiveness of the proposed two models in attaining a higher voltage stable system at lower cost. 1. A novel nonlinear VSCOPF formulation based on a set of line-wise power balance equations and LVCI is developed.
Electricity jurisdictions procure generation capacity requirements competitively which maintains ... more Electricity jurisdictions procure generation capacity requirements competitively which maintains investment flows into the electricity system infrastructure. The capacity market auction is one of such competitive capacity procurement methods. It is challenging to consider energy storage (ES) capacity offers in capacity markets due to complex capacity contribution characteristics and lack of explicit mechanisms to integrate them. However, ES capacity can be used to manage the system peak demand. ES can substitute for peaker plants, especially if the demand curve is kurtosis. This paper proposes novel ES capacity contribution formulas and a comprehensive capacity auction model which is designed to consider capacity offers including energy-limited technologies such as ES. After all offers are converted to unforced capacity (UCAP), their energy limitations do not affect bid selection in the market. The proposed novel ES UCAP computation formulas consider power capacity, energy capacity and operational attributes. This paper also presents the results of a case study with three capacity supply offers and a case study based on actual Ontario system data. A detailed sensitivity analysis is also included in the paper to show the validity of the proposed ES UCAP formulas in the auction model. The proposed formulas provide significant benefits in successfully procuring ES capacity offers.