Nader Samaan - Academia.edu (original) (raw)

Papers by Nader Samaan

Power electronics and power systems, 2017

The study described in this chapter demonstrates the benefits of BA consolidation with the help o... more The study described in this chapter demonstrates the benefits of BA consolidation with the help of a detailed WECC system model and advanced methodology, which is also described in this chapter. The study aims to determine the potential savings in production cost and reduction in balancing reserve requirements in the WECC system. The study has found that effective use of the diversity in load and variable generation over a wide area can indeed help to achieve significant savings. The implementation cost for the consolidation was beyond the scope of this study. The analysis was performed for two different scenarios of VG penetration: 11% (8% wind and 3% solar) and 33% (24% wind and 9% solar) of WECC projected energy demand in 2020.

Forecasts errors in variable generation and load are usually assumed to be normally distributed. ... more Forecasts errors in variable generation and load are usually assumed to be normally distributed. This supposition is used as the basis for estimating these errors' uncertainty and consequences for a power system. Another assumption is that the forecast errors are stationary processes with time-independent probability distributions. These hypotheses, however, are not always valid. In this paper, we introduce a new approach without implying normal distributions and stationarity of forecast errors. In addition, it is desired to more accurately quantify the forecast uncertainty by reducing prediction intervals of forecasts. We use automatically coupled wavelet transform and autoregressive integrated moving-average (ARIMA) forecasting to reflect multi-scale variability of forecast errors. The proposed analysis reveals slow-changing “quasi-deterministic” components of forecast errors. This helps improve forecasts produced by other means, e.g., using weather-based models, and reduce forecast errors prediction intervals. Thus, we demonstrate the possibility of uncertainty reduction for wind, solar, and load forecast errors by 10-12%.

2022 IEEE Energy Conversion Congress and Exposition (ECCE), Oct 9, 2022

This paper presents a method for conducting continuation power flow simulation on high-solar pene... more This paper presents a method for conducting continuation power flow simulation on high-solar penetration distribution feeders. A load disaggregation method is developed to disaggregate the daily feeder load profiles collected in substations down to each load node, where the electricity consumption of residential houses and commercial buildings are modeled using actual data collected from single family houses and commercial buildings. This allows the modeling of power flow and voltage profile along a distribution feeder on a continuing fashion for a 24-hour period at minute-by-minute resolution. By separating the feeder into load zones based on the distance between the load node and the feeder head, we studied the impact of PV penetration on distribution grid operation in different seasons and under different weather conditions for different PV placements.

Protection systems in modern power networks have been identified by the North American Electric R... more Protection systems in modern power networks have been identified by the North American Electric Reliability Corporation as a critical reliability issue. GE PSLF is one of the most widely used power system analysis tools in the industry. This paper explains how protection systems are modeled using generic relay models for system-wide simulation and the enhancements being made in PSLF to the grid dynamic models for transmission, generation, and load protection. The impact of the protection systems during extreme contingencies and the process of cascading outages have been simulated using the Dynamic Contingency Analysis Tool. A case study is given to show the effect of protection devices on dynamic simulations. This approach can be used by planning engineers to add protection models in dynamic simulations. Undervoltage, underfrequency, overvoltage, and overfrequency relays for each generator, distance relay protection for transmission systems, and four types of load-shedding relay schemes for loads have been modeled in this case study.

IEEE Access, 2023

The 100% renewable energy targets from the policymakers for the future grids have drawn a signifi... more The 100% renewable energy targets from the policymakers for the future grids have drawn a significant amount of interest. The high renewable penetration made future large interconnected grids (LIGs) more volatile and harder to understand using historical observations. This led to the need to study future LIGs using a wide range of future-year operating conditions and contingencies. However, existing planning tools are not sufficient for the dynamic security assessment (DSA) of these future LIGs due to a lack of detailed modeling capabilities and computational limitations when processing a wide range of scenarios. This paper addresses these two challenges by proposing; 1) an efficient modeling framework that can generate large grid's dynamic data with cascade behaviors for a wide range of scenarios. This data is generated by respecting the constraints of production cost models and their respective AC power flow dynamic simulation models at an hourly resolution; 2) an unsupervised machine learning(ML)-based approach for fast scanning the DSA data. The proposed approach uses feature engineering techniques and fast Fourier transforms to transform the time series signals into visually distinguishable frequency domain signals for DSA. The proposed simulation framework is used to generate 1.485 terabytes of dynamic simulation data for the 2028 WECC system containing 4455 scenarios. The proposed ML framework used the 2028 WECC system to demonstrate its effectiveness and speed in identifying critical scenarios. INDEX TERMS Dynamic security assessment, unsupervised learning, feature engineering, large grids.

IEEE Access, 2023

There is a lot of interest in the policymakers' plans to have grids run entirely on renewable ene... more There is a lot of interest in the policymakers' plans to have grids run entirely on renewable energy in the upcoming years. As a result of the high renewable penetration, future large interconnected grids (LIGs) become more volatile and difficult to operate. To understand future grids better, the planning studies of future grids must consider a wide range of operating conditions and contingencies. In this paper, we propose a novel future grid planning framework that can simulate a wide range of operating conditions and contingencies while considering future policy and topology changes, production cost models, dynamics, steady state AC power flow, and cascade constraints. Using this proposed framework, we propose an approach to identify voltage stability critical locations in the future grid without assumptions on switching devices and load change trajectories during system collapse, while also considering the cascading/time-series behavior of future LIGs. The proposed future grid planning framework is used to generate 1.485 terabytes of dynamic simulation data for 2028 WECC system containing 4455 scenarios. The proposed voltage stability approach is demonstrated on the 2028 representation of the WECC system, and IEEE 30, 300-bus systems. INDEX TERMS Voltage stability analysis, very large grid analysis, WECC system, high renewable penetration. NOMENCLATURE ABBREVIATIONS ADS Anchor Data Set. DCAT Dynamic Contingency Analysis Tool [1]. LCI Local Computation Index. LIG Large Interconnected Grid. LTVI Long-term Voltage Instability. OLTC On Load Tap Changer. PCM Production Cost Model. VCP Voltage Collapse Point. The associate editor coordinating the review of this manuscript and approving it for publication was Xiaodong Liang .

2021 IEEE Power & Energy Society General Meeting (PESGM), Jul 26, 2021

arXiv (Cornell University), Feb 17, 2020

This paper presents a network hardware-in-theloop (HIL) simulation system for modeling large-scal... more This paper presents a network hardware-in-theloop (HIL) simulation system for modeling large-scale power systems. Researchers have developed many HIL test systems for power systems in recent years. Those test systems can model both microsecond-level dynamic responses of power electronic systems and millisecond-level transients of transmission and distribution grids. By integrating individual HIL test systems into a network of HIL test systems, we can create large-scale power grid digital twins with flexible structures at required modeling resolution that fits for a wide range of system operating conditions. This will not only significantly reduce the need for field tests when developing new technologies but also greatly shorten the model development cycle. In this paper, we present a networked OPAL-RT based HIL test system for developing transmission-distribution coordinative Volt-VAR regulation technologies as an example to illustrate system setups, communication requirements among different HIL simulation systems, and system connection mechanisms. Impacts of communication delays, information exchange cycles, and computing delays are illustrated. Simulation results show that the performance of a networked HIL test system is satisfactory. Index Termsco-simulation, digital twin, distribution system, hardware-in-the-loop, transmission system, Volt-VAR control. systems. The setup of a coordinated real-time sub-transmission Volt-VAR control (VVC) testbed (CReS-VCT) that cosimulates transmission-distribution-DER systems is used as an example to illustrate the proposed framework. Implementations and simulation models were developed by research teams at Pacific Northwest National Laboratory (PNNL), North Carolina State University (NC State), and the University of Texas at Austin (UT-Austin). Measurements and control actions among HIL simulators are communicated via a virtual private network (VPN) tunnel or a shared-file method. The

The behavior of modern power systems is becoming more stochastic and dynamic, due to the increase... more The behavior of modern power systems is becoming more stochastic and dynamic, due to the increased penetration of variable generation, demand response, new power market structure, extreme weather conditions, contingencies, and unexpected events. It is critically important to predict potential system operational issues so that grid planners and operators can take preventive actions to mitigate the impact, e.g., lack of operational reserves. In this paper, an innovative software tool is presented to assist power grid operators in a balancing authority in predicting the grid stress level over the next operating day. It periodically collects necessary information from public domain such as weather forecasts, electricity demand, and automatically estimates the stress levels on a daily basis. Advanced Neural Network and regression tree algorithms are developed as the prediction engines to achieve this goal. The tool has been tested on a few key balancing authorities and successfully predicted the growing system peak load and increased stress levels under extreme heat waves.

OSTI OAI (U.S. Department of Energy Office of Scientific and Technical Information), Jul 12, 2022

2020 IEEE Power & Energy Society General Meeting (PESGM)

Modular multilevel converters (MMCs) are widely used in the design of modern high-voltage direct ... more Modular multilevel converters (MMCs) are widely used in the design of modern high-voltage direct current (HVdc) transmission system. High-fidelity dynamic models of MMCsbased HVdc system require small simulation time step and can be accurately modeled in electromagnetic transient (EMT) simulation programs. The EMT program exhibits slow simulation speed and limitation on the size of the model and brings certain challenges to test the high-fidelity HVdc model in system-level simulations. This paper presents the design and implementation of a hybrid simulation framework, which enables the co-simulation of the EMT model of Atlanta-Orlando HVdc line and the transient stability (TS) model of the entire Eastern Interconnection system. This paper also introduces the implementation of two high-fidelity HVdc line models simulated at different time steps and discusses a dedicated method for sizing the buffer areas on both sides of the HVdc line. The simulation results of the two HVdc models with different sizes of buffer areas are presented and compared.

The electrical transmission system of California, like all interconnected transmission systems, i... more The electrical transmission system of California, like all interconnected transmission systems, is vulnerable to extreme events in which complicated chains of exceptional events cascade to cause a widespread blackout across the state and beyond. These large blackouts always have a substantial impact on citizens, business and government, and although they are rare events, they pose a substantial risk. Much is known about avoiding the first few failures near the beginnings of the cascades, but there are no established methods for directly analyzing the risks of the subsequent long chains of events. The project objective is to find ways to assess, manage and mitigate the risk of extreme blackout events. Since this is a difficult and complex problem, multiple approaches are pursued, including examining historical blackout data, making detailed models of the grid, processing simulated data from advanced simulations, and developing and testing new ideas and methods. The methods include finding critical elements and system vulnerabilities, modeling and simulation, quantifying cascade propagation, and complex systems and statistical analyses. The project team combines leading experts from industry, a national laboratory and academia.

2017 IEEE Power & Energy Society General Meeting, 2017

Voltage and reactive power system control is generally performed following usual patterns of load... more Voltage and reactive power system control is generally performed following usual patterns of loads, based on off-line studies for daily and seasonal operations. This practice is currently challenged by the inclusion of distributed renewable generation, such as solar. There has been focus on resolving this problem at the distribution level; however, the transmission and sub-transmission levels have received less attention. This paper provides a literature review of proposed methods and solution approaches to coordinate and optimize voltage control and reactive power management, with an emphasis on applications at transmission and sub-transmission level. The conclusion drawn from the survey is that additional research is needed in the areas of optimizing switch shunt actions and coordinating all available resources to deal with uncertain patterns from increasing distributed renewable generation in the operational time frame. These topics are not deeply explored in the literature.

Power electronics and power systems, 2017

The study described in this chapter demonstrates the benefits of BA consolidation with the help o... more The study described in this chapter demonstrates the benefits of BA consolidation with the help of a detailed WECC system model and advanced methodology, which is also described in this chapter. The study aims to determine the potential savings in production cost and reduction in balancing reserve requirements in the WECC system. The study has found that effective use of the diversity in load and variable generation over a wide area can indeed help to achieve significant savings. The implementation cost for the consolidation was beyond the scope of this study. The analysis was performed for two different scenarios of VG penetration: 11% (8% wind and 3% solar) and 33% (24% wind and 9% solar) of WECC projected energy demand in 2020.

Forecasts errors in variable generation and load are usually assumed to be normally distributed. ... more Forecasts errors in variable generation and load are usually assumed to be normally distributed. This supposition is used as the basis for estimating these errors' uncertainty and consequences for a power system. Another assumption is that the forecast errors are stationary processes with time-independent probability distributions. These hypotheses, however, are not always valid. In this paper, we introduce a new approach without implying normal distributions and stationarity of forecast errors. In addition, it is desired to more accurately quantify the forecast uncertainty by reducing prediction intervals of forecasts. We use automatically coupled wavelet transform and autoregressive integrated moving-average (ARIMA) forecasting to reflect multi-scale variability of forecast errors. The proposed analysis reveals slow-changing “quasi-deterministic” components of forecast errors. This helps improve forecasts produced by other means, e.g., using weather-based models, and reduce forecast errors prediction intervals. Thus, we demonstrate the possibility of uncertainty reduction for wind, solar, and load forecast errors by 10-12%.

2022 IEEE Energy Conversion Congress and Exposition (ECCE), Oct 9, 2022

This paper presents a method for conducting continuation power flow simulation on high-solar pene... more This paper presents a method for conducting continuation power flow simulation on high-solar penetration distribution feeders. A load disaggregation method is developed to disaggregate the daily feeder load profiles collected in substations down to each load node, where the electricity consumption of residential houses and commercial buildings are modeled using actual data collected from single family houses and commercial buildings. This allows the modeling of power flow and voltage profile along a distribution feeder on a continuing fashion for a 24-hour period at minute-by-minute resolution. By separating the feeder into load zones based on the distance between the load node and the feeder head, we studied the impact of PV penetration on distribution grid operation in different seasons and under different weather conditions for different PV placements.

Protection systems in modern power networks have been identified by the North American Electric R... more Protection systems in modern power networks have been identified by the North American Electric Reliability Corporation as a critical reliability issue. GE PSLF is one of the most widely used power system analysis tools in the industry. This paper explains how protection systems are modeled using generic relay models for system-wide simulation and the enhancements being made in PSLF to the grid dynamic models for transmission, generation, and load protection. The impact of the protection systems during extreme contingencies and the process of cascading outages have been simulated using the Dynamic Contingency Analysis Tool. A case study is given to show the effect of protection devices on dynamic simulations. This approach can be used by planning engineers to add protection models in dynamic simulations. Undervoltage, underfrequency, overvoltage, and overfrequency relays for each generator, distance relay protection for transmission systems, and four types of load-shedding relay schemes for loads have been modeled in this case study.

IEEE Access, 2023

The 100% renewable energy targets from the policymakers for the future grids have drawn a signifi... more The 100% renewable energy targets from the policymakers for the future grids have drawn a significant amount of interest. The high renewable penetration made future large interconnected grids (LIGs) more volatile and harder to understand using historical observations. This led to the need to study future LIGs using a wide range of future-year operating conditions and contingencies. However, existing planning tools are not sufficient for the dynamic security assessment (DSA) of these future LIGs due to a lack of detailed modeling capabilities and computational limitations when processing a wide range of scenarios. This paper addresses these two challenges by proposing; 1) an efficient modeling framework that can generate large grid's dynamic data with cascade behaviors for a wide range of scenarios. This data is generated by respecting the constraints of production cost models and their respective AC power flow dynamic simulation models at an hourly resolution; 2) an unsupervised machine learning(ML)-based approach for fast scanning the DSA data. The proposed approach uses feature engineering techniques and fast Fourier transforms to transform the time series signals into visually distinguishable frequency domain signals for DSA. The proposed simulation framework is used to generate 1.485 terabytes of dynamic simulation data for the 2028 WECC system containing 4455 scenarios. The proposed ML framework used the 2028 WECC system to demonstrate its effectiveness and speed in identifying critical scenarios. INDEX TERMS Dynamic security assessment, unsupervised learning, feature engineering, large grids.

IEEE Access, 2023

There is a lot of interest in the policymakers' plans to have grids run entirely on renewable ene... more There is a lot of interest in the policymakers' plans to have grids run entirely on renewable energy in the upcoming years. As a result of the high renewable penetration, future large interconnected grids (LIGs) become more volatile and difficult to operate. To understand future grids better, the planning studies of future grids must consider a wide range of operating conditions and contingencies. In this paper, we propose a novel future grid planning framework that can simulate a wide range of operating conditions and contingencies while considering future policy and topology changes, production cost models, dynamics, steady state AC power flow, and cascade constraints. Using this proposed framework, we propose an approach to identify voltage stability critical locations in the future grid without assumptions on switching devices and load change trajectories during system collapse, while also considering the cascading/time-series behavior of future LIGs. The proposed future grid planning framework is used to generate 1.485 terabytes of dynamic simulation data for 2028 WECC system containing 4455 scenarios. The proposed voltage stability approach is demonstrated on the 2028 representation of the WECC system, and IEEE 30, 300-bus systems. INDEX TERMS Voltage stability analysis, very large grid analysis, WECC system, high renewable penetration. NOMENCLATURE ABBREVIATIONS ADS Anchor Data Set. DCAT Dynamic Contingency Analysis Tool [1]. LCI Local Computation Index. LIG Large Interconnected Grid. LTVI Long-term Voltage Instability. OLTC On Load Tap Changer. PCM Production Cost Model. VCP Voltage Collapse Point. The associate editor coordinating the review of this manuscript and approving it for publication was Xiaodong Liang .

2021 IEEE Power & Energy Society General Meeting (PESGM), Jul 26, 2021

arXiv (Cornell University), Feb 17, 2020

This paper presents a network hardware-in-theloop (HIL) simulation system for modeling large-scal... more This paper presents a network hardware-in-theloop (HIL) simulation system for modeling large-scale power systems. Researchers have developed many HIL test systems for power systems in recent years. Those test systems can model both microsecond-level dynamic responses of power electronic systems and millisecond-level transients of transmission and distribution grids. By integrating individual HIL test systems into a network of HIL test systems, we can create large-scale power grid digital twins with flexible structures at required modeling resolution that fits for a wide range of system operating conditions. This will not only significantly reduce the need for field tests when developing new technologies but also greatly shorten the model development cycle. In this paper, we present a networked OPAL-RT based HIL test system for developing transmission-distribution coordinative Volt-VAR regulation technologies as an example to illustrate system setups, communication requirements among different HIL simulation systems, and system connection mechanisms. Impacts of communication delays, information exchange cycles, and computing delays are illustrated. Simulation results show that the performance of a networked HIL test system is satisfactory. Index Termsco-simulation, digital twin, distribution system, hardware-in-the-loop, transmission system, Volt-VAR control. systems. The setup of a coordinated real-time sub-transmission Volt-VAR control (VVC) testbed (CReS-VCT) that cosimulates transmission-distribution-DER systems is used as an example to illustrate the proposed framework. Implementations and simulation models were developed by research teams at Pacific Northwest National Laboratory (PNNL), North Carolina State University (NC State), and the University of Texas at Austin (UT-Austin). Measurements and control actions among HIL simulators are communicated via a virtual private network (VPN) tunnel or a shared-file method. The

The behavior of modern power systems is becoming more stochastic and dynamic, due to the increase... more The behavior of modern power systems is becoming more stochastic and dynamic, due to the increased penetration of variable generation, demand response, new power market structure, extreme weather conditions, contingencies, and unexpected events. It is critically important to predict potential system operational issues so that grid planners and operators can take preventive actions to mitigate the impact, e.g., lack of operational reserves. In this paper, an innovative software tool is presented to assist power grid operators in a balancing authority in predicting the grid stress level over the next operating day. It periodically collects necessary information from public domain such as weather forecasts, electricity demand, and automatically estimates the stress levels on a daily basis. Advanced Neural Network and regression tree algorithms are developed as the prediction engines to achieve this goal. The tool has been tested on a few key balancing authorities and successfully predicted the growing system peak load and increased stress levels under extreme heat waves.

OSTI OAI (U.S. Department of Energy Office of Scientific and Technical Information), Jul 12, 2022

2020 IEEE Power & Energy Society General Meeting (PESGM)

Modular multilevel converters (MMCs) are widely used in the design of modern high-voltage direct ... more Modular multilevel converters (MMCs) are widely used in the design of modern high-voltage direct current (HVdc) transmission system. High-fidelity dynamic models of MMCsbased HVdc system require small simulation time step and can be accurately modeled in electromagnetic transient (EMT) simulation programs. The EMT program exhibits slow simulation speed and limitation on the size of the model and brings certain challenges to test the high-fidelity HVdc model in system-level simulations. This paper presents the design and implementation of a hybrid simulation framework, which enables the co-simulation of the EMT model of Atlanta-Orlando HVdc line and the transient stability (TS) model of the entire Eastern Interconnection system. This paper also introduces the implementation of two high-fidelity HVdc line models simulated at different time steps and discusses a dedicated method for sizing the buffer areas on both sides of the HVdc line. The simulation results of the two HVdc models with different sizes of buffer areas are presented and compared.

The electrical transmission system of California, like all interconnected transmission systems, i... more The electrical transmission system of California, like all interconnected transmission systems, is vulnerable to extreme events in which complicated chains of exceptional events cascade to cause a widespread blackout across the state and beyond. These large blackouts always have a substantial impact on citizens, business and government, and although they are rare events, they pose a substantial risk. Much is known about avoiding the first few failures near the beginnings of the cascades, but there are no established methods for directly analyzing the risks of the subsequent long chains of events. The project objective is to find ways to assess, manage and mitigate the risk of extreme blackout events. Since this is a difficult and complex problem, multiple approaches are pursued, including examining historical blackout data, making detailed models of the grid, processing simulated data from advanced simulations, and developing and testing new ideas and methods. The methods include finding critical elements and system vulnerabilities, modeling and simulation, quantifying cascade propagation, and complex systems and statistical analyses. The project team combines leading experts from industry, a national laboratory and academia.

2017 IEEE Power & Energy Society General Meeting, 2017

Voltage and reactive power system control is generally performed following usual patterns of load... more Voltage and reactive power system control is generally performed following usual patterns of loads, based on off-line studies for daily and seasonal operations. This practice is currently challenged by the inclusion of distributed renewable generation, such as solar. There has been focus on resolving this problem at the distribution level; however, the transmission and sub-transmission levels have received less attention. This paper provides a literature review of proposed methods and solution approaches to coordinate and optimize voltage control and reactive power management, with an emphasis on applications at transmission and sub-transmission level. The conclusion drawn from the survey is that additional research is needed in the areas of optimizing switch shunt actions and coordinating all available resources to deal with uncertain patterns from increasing distributed renewable generation in the operational time frame. These topics are not deeply explored in the literature.