R. Baldick - Profile on Academia.edu (original) (raw)
Papers by R. Baldick
Conference Record of the Thirty-Sixth Asilomar Conference on Signals, Systems and Computers, 2002.
In a multicarrier modulation system, a time domain equalizer (TEQ) traditionally shortens the tra... more In a multicarrier modulation system, a time domain equalizer (TEQ) traditionally shortens the transmission channel impulse response (CIR) to mitigate intersymbol interference (ISI). In this paper, we propose a data-rate optimal TEQ filter bank whose data rates at the equalizer output are significantly better than those of the Maximum Bit Rate and Minimum ISI methods and similar to those of the least-squares per-tone equalizer method for ADSL CIRs, transmit filters, and receive filters. The contributions of this paper are: (1) a new model for multicarrier demodulator output SNR that includes ISI, near-end crosstalk, white Gaussian noise, and the digital noise floor; (2) data rate optimal time domain per-tone TEQ filter bank, and (3) a new achievable upper bound on achievable bit rate.
Renewable Energy and Power Quality Journal, 2012
A battery system is designed to reduce violations of ramping limit due to severe and long ramps o... more A battery system is designed to reduce violations of ramping limit due to severe and long ramps of wind power output. The power rating, battery capacity, and operational policies of the battery are decided based on the assumption that the wind power output follows the Variance Gamma (V.G.) process over short time interval. The histogram of the ramp rates of wind power follows the symmetric Laplace distribution. Furthermore, ramp rates have independent and stationary increments, and their variances are proportional to the time interval. Consequently, the wind power output can be modelled as a simple form of the V.G. process. Battery operational oplicies based on the V.G. process are tested using statistics representing the sum of all wind power outputs from wind farms in the Electric Reliability Council of Texas (ERCOT). It is found that the battery can essentially eliminate violations of ramping limits due to severe ramp events. Furthermore, in this operation, it is discovered that the power rating influences the ramp limiting performance of the battery more than battery storage rating.
IEEE Transactions on Power Delivery, 2009
In this paper, we estimate the costs of increasing transmission system capability through technol... more In this paper, we estimate the costs of increasing transmission system capability through technologies for uprating transmission capacity without expanding the transmission footprint. We compare costs for uprating to the costs of new capacity. Index Terms-Flexible AC transmission systems (FACTS), transmission assets.
Journal of Regulatory Economics, 1993
We characterize the cost function for electric power transmission. It is complex and non-linear, ... more We characterize the cost function for electric power transmission. It is complex and non-linear, •exhibiting scale economies over its range. The social planning problem for network transmission expansion is illustrated with a simple numerical example. The regulatory problem for joint generation and transmission cost minimization is addressed. It is shown that information asymmetries about the transmission cost function can lead to coordination losses when there is competition in the generation segment. We parametrize the tradeoff between potential coordination losses in transmission planning and benefits of competition and examine some potential alternatives for improved regulation of the transmission planning J.>rocess.
Proceedings 2001 IEEE International Conference on Computer Design: VLSI in Computers and Processors. ICCD 2001
IEEE Transactions on Power Systems, 2011
This paper proposes a novel approach to optimize a generator's profit in an offer-based electrici... more This paper proposes a novel approach to optimize a generator's profit in an offer-based electricity market cleared by an optimal power flow (OPF) program. A generator's offer is optimized based on its transmission-constrained residual demand derivative (TCRDD), which avoids representing the full network model in the optimization. The TCRDD can be easily calculated based on a solved OPF without changing existing OPF algorithms and programs. As demonstrated with an IEEE 118-bus example, the TCRDD approach is computationally efficient. The TCRDD approach can help market participants to bid into electricity markets, and help market monitors to diagnose bidding behaviors in the presence of transmission constraints.
IEEE Transactions on Power Systems, 2007
In this paper a property rights model for electric transmission is proposed and its properties an... more In this paper a property rights model for electric transmission is proposed and its properties analyzed. The proposed rights, called "border flow rights," support financial hedging of transmission risk and merchant transmission expansion through associated financial rights, called "contracts for differences of differences." These financial rights allow for forward trading of both energy and transmission by a unified exchange, avoiding the bifurcation in current markets between decentralized longterm energy trading and centralized long-term transmission trading. Such long-term trading can help to support the financing of both generation and transmission assets. We consider incentive properties of such a right in the absence of lumpiness, economies of scale, and market power.
Proceedings of the ASP-DAC '99 Asia and South Pacific Design Automation Conference 1999 (Cat. No.99EX198), 1999
We p r e s e n t a p p r o ximations to non-smooth continuous functions by di erentiable function... more We p r e s e n t a p p r o ximations to non-smooth continuous functions by di erentiable functions which are parameterized by a scalar 0 and have convenient limit behavior as ! 0. For standard numerical methods, this translates into a tradeo between solution quality and speed. We s h o w the utility o f our approximations for wirelength and delay estimations used by analytical placers for VLSI layout. Our approximations lead to more solvable" problems.
In this paper we investigate the multiplexing of heterogeneous applications and the pricing of tr... more In this paper we investigate the multiplexing of heterogeneous applications and the pricing of transmission services on an ATM network. Pricing is of interest for network management to promote efficient utilization of resources. A framework is presented in which users select from a menu of services, are peak-rate policed, and are charged according to their usage and connection time. We illustrate the considerable improvement in network utilization possible compared to a traditional
2019 American Control Conference (ACC), Jul 1, 2019
Standard economic dispatch problems that consider line losses are linear approximations of a non-... more Standard economic dispatch problems that consider line losses are linear approximations of a non-convex economic dispatch problem formulated by fixing voltage magnitudes and assuming the decoupling of real and reactive power. This paper formulates and analyzes the general non-convex economic dispatch problem, incorporating and generalizing the Fictitious Nodal Demand (FND) model, resulting in a slack bus independent formulation that provides insight into standard formulations by pointing out commonly used but unnecessary assumptions and by deriving proper choices of "tuning parameters." The proper choice of loss allocation is derived to assign half of the losses of each transmission line to adjacent buses, justifying approaches in the literature. Line constraints are proposed in the form of voltage angle difference limits and are proven equivalent to various other line limits including current magnitude limits and mid-line power flow limits. The formulated general economic dispatch problem with marginal losses consistently models flows and loss approximation, results in approximately correct outcomes and is proven to be reference bus independent. Various approximations of this problem are compared using realistically large transmission network test cases.
Optimal Data Attacks on Power Grids: Leveraging Detection & Measurement Jamming
Meter measurements in the power grid are susceptible to manipulation by adversaries, that can lea... more Meter measurements in the power grid are susceptible to manipulation by adversaries, that can lead to errors in state estimation. This paper presents a general framework to study attacks on state estimation by adversaries capable of injecting bad-data into measurements and further, of jamming their reception. Through these two techniques, a novel `detectable jamming' attack is designed that changes the state estimation despite failing bad-data detection checks. Compared to commonly studied `hidden' data attacks, these attacks have lower costs and a wider feasible operating region. It is shown that the entire domain of jamming costs can be divided into two regions, with distinct graph-cut based formulations for the design of the optimal attack. The most significant insight arising from this result is that the adversarial capability to jam measurements changes the optimal 'detectable jamming' attack design only if the jamming cost is less than half the cost of bad-data...
A Stochastic Transmission Planning Model With Dependent Load and Wind Forecasts
IEEE Transactions on Power Systems
This paper introduces a two-stage stochastic program for transmission planning. The model has two... more This paper introduces a two-stage stochastic program for transmission planning. The model has two dependent random variables, namely, total electric load and available wind power. Given univariate marginal distributions for these two random variables and their correlation coefficient, the joint distribution is modeled using a Gaussian copula. The optimal power flow (OPF) problem is solved based on the linearized direct current (DC) power flow. The Electric Reliability Council of Texas (ERCOT) network model and its load and wind data are used for a test case. A 95% confidence interval is formed on the optimality gap of candidate solutions obtained using a sample average approximation with 200 and 300 samples from the joint distribution of load and wind.
Spatial prediction of wind farm outputs using the Augmented Kriging-based Model
2012 IEEE Power and Energy Society General Meeting, 2012
ABSTRACT
Case study of an improved Cascading Outage Analysis model using outage checkers
2013 IEEE Power & Energy Society General Meeting, 2013
ABSTRACT
ECE Dept., Univ. of Texas at Austin, Austin, TX, USA
Robustified Reserve Modelling for Wind PowerIntegration in Ramp-Based Unit Commitment
In recent years, high penetration of variable generating sources, such as wind power, has challen... more In recent years, high penetration of variable generating sources, such as wind power, has challenged independent system operators (ISO) in keeping a cheap and reliable power system operation. Any deviation between expected and real wind production must be absorbed by the power system resources (reserves), which must be available and ready to be deployed in real time. To guarantee this resource availability, the system resources must be committed in advance, usually the day-ahead, by solving the so-called unit commitment (UC) problem. If the quantity of committed resources is extremely low, there will be devastating and costly consequences in the system, such as significant load shedding. On the other hand, if this quantity is extremely high, the system operation will be excessively expensive, mainly because facilities will not be fully exploited.This thesis proposes computationally efficient models for optimal day-ahead planning in (thermal) power systems to adequately face the stochastic nature of wind production in the real-time system operation. The models can support ISOs to face the new challenges in short-term planning as uncertainty increases dramatically due to the integration of variable generating resources. This thesis then tackles the UC problem in the following aspects: Power system representation: This thesis identifies drawbacks of the traditional energy-block scheduling approach, which make it unable to adequately prepare the power system to face deterministic and perfectly known events. To overcome those drawbacks, we propose the ramp-based scheduling approach that more accurately describes the system operation, thus better exploiting the system flexibility.UC computational performance: Developing more accurate models would be pointless if these models considerably increase the computational burden of the UC problem, which is already a complex integer and non-convex problem. We then devise simultaneously tight and compact formulations under the mixed-integer programming (MIP) approach. This simultaneous characteristic reinforces the convergence speed by reducing the search space (tightness) and simultaneously increasing the searching speed (compactness) with which solvers explore that reduced space.Uncertainty management in UC: By putting together the improvements in the previous two aspects, this thesis contributes to a better management of wind uncertainty in UC, even though these two aspects are in conflict and improving one often means harming the other. If compared with a traditional energy-block UC model under the stochastic (deterministic) paradigm, a stochastic (deterministic) ramp-based UC model: 1) leads to more economic operation, due to a better and more detailed system representation, while 2) being solved significantly faster, because the core of the model is built upon simultaneously tight and compact MIP formulations.To further improve the uncertainty management in the proposed ramp-based UC, we extend the formulation to a network-constrained UC with robust reserve modelling. Based on robust optimization insights, the UC solution guarantees feasibility for any realization of the uncertain wind production, within the considered uncertainty ranges. This final model remains as a pure linear MIP problem whose size does not depend on the uncertainty representation, thus avoiding the inherent computational complications of the stochastic and robust UCs commonly found in the literature.
Hidden Attacks on Power Grid: Optimal Attack Strategies and Mitigation
State estimation distributed processing [discussion and closure]
IEEE Transactions on Power Systems, 2001
J. Aguado and V. Quintana comment on the paper by R. Ebrahimian and R. Baldick (see ibid., vol.15... more J. Aguado and V. Quintana comment on the paper by R. Ebrahimian and R. Baldick (see ibid., vol.15, no.4, p.1240-6, 2000), and ask for comments on five points relating to their own work in this area of power network state estimation. The original authors reply to the comments
Coarse-grained distributed optimal power flow
IEEE Transactions on Power Systems, 1997
Dispatchable transmission in RTO markets
IEEE Transactions on Power Systems, 2005
We consider transmission owners that bid capacity, under appropriate Regional Transmission Organi... more We consider transmission owners that bid capacity, under appropriate Regional Transmission Organization (RTO) market rules, at a positive price into forward and spot (dispatch) auctions to derive congestion revenues. This can encompass daily, monthly, or multimonthly auctions, allowing for commitment of transmission to reflect market needs in different time periods, e.g., seasons. We provide two and three node examples and
Conference Record of the Thirty-Sixth Asilomar Conference on Signals, Systems and Computers, 2002.
In a multicarrier modulation system, a time domain equalizer (TEQ) traditionally shortens the tra... more In a multicarrier modulation system, a time domain equalizer (TEQ) traditionally shortens the transmission channel impulse response (CIR) to mitigate intersymbol interference (ISI). In this paper, we propose a data-rate optimal TEQ filter bank whose data rates at the equalizer output are significantly better than those of the Maximum Bit Rate and Minimum ISI methods and similar to those of the least-squares per-tone equalizer method for ADSL CIRs, transmit filters, and receive filters. The contributions of this paper are: (1) a new model for multicarrier demodulator output SNR that includes ISI, near-end crosstalk, white Gaussian noise, and the digital noise floor; (2) data rate optimal time domain per-tone TEQ filter bank, and (3) a new achievable upper bound on achievable bit rate.
Renewable Energy and Power Quality Journal, 2012
A battery system is designed to reduce violations of ramping limit due to severe and long ramps o... more A battery system is designed to reduce violations of ramping limit due to severe and long ramps of wind power output. The power rating, battery capacity, and operational policies of the battery are decided based on the assumption that the wind power output follows the Variance Gamma (V.G.) process over short time interval. The histogram of the ramp rates of wind power follows the symmetric Laplace distribution. Furthermore, ramp rates have independent and stationary increments, and their variances are proportional to the time interval. Consequently, the wind power output can be modelled as a simple form of the V.G. process. Battery operational oplicies based on the V.G. process are tested using statistics representing the sum of all wind power outputs from wind farms in the Electric Reliability Council of Texas (ERCOT). It is found that the battery can essentially eliminate violations of ramping limits due to severe ramp events. Furthermore, in this operation, it is discovered that the power rating influences the ramp limiting performance of the battery more than battery storage rating.
IEEE Transactions on Power Delivery, 2009
In this paper, we estimate the costs of increasing transmission system capability through technol... more In this paper, we estimate the costs of increasing transmission system capability through technologies for uprating transmission capacity without expanding the transmission footprint. We compare costs for uprating to the costs of new capacity. Index Terms-Flexible AC transmission systems (FACTS), transmission assets.
Journal of Regulatory Economics, 1993
We characterize the cost function for electric power transmission. It is complex and non-linear, ... more We characterize the cost function for electric power transmission. It is complex and non-linear, •exhibiting scale economies over its range. The social planning problem for network transmission expansion is illustrated with a simple numerical example. The regulatory problem for joint generation and transmission cost minimization is addressed. It is shown that information asymmetries about the transmission cost function can lead to coordination losses when there is competition in the generation segment. We parametrize the tradeoff between potential coordination losses in transmission planning and benefits of competition and examine some potential alternatives for improved regulation of the transmission planning J.>rocess.
Proceedings 2001 IEEE International Conference on Computer Design: VLSI in Computers and Processors. ICCD 2001
IEEE Transactions on Power Systems, 2011
This paper proposes a novel approach to optimize a generator's profit in an offer-based electrici... more This paper proposes a novel approach to optimize a generator's profit in an offer-based electricity market cleared by an optimal power flow (OPF) program. A generator's offer is optimized based on its transmission-constrained residual demand derivative (TCRDD), which avoids representing the full network model in the optimization. The TCRDD can be easily calculated based on a solved OPF without changing existing OPF algorithms and programs. As demonstrated with an IEEE 118-bus example, the TCRDD approach is computationally efficient. The TCRDD approach can help market participants to bid into electricity markets, and help market monitors to diagnose bidding behaviors in the presence of transmission constraints.
IEEE Transactions on Power Systems, 2007
In this paper a property rights model for electric transmission is proposed and its properties an... more In this paper a property rights model for electric transmission is proposed and its properties analyzed. The proposed rights, called "border flow rights," support financial hedging of transmission risk and merchant transmission expansion through associated financial rights, called "contracts for differences of differences." These financial rights allow for forward trading of both energy and transmission by a unified exchange, avoiding the bifurcation in current markets between decentralized longterm energy trading and centralized long-term transmission trading. Such long-term trading can help to support the financing of both generation and transmission assets. We consider incentive properties of such a right in the absence of lumpiness, economies of scale, and market power.
Proceedings of the ASP-DAC '99 Asia and South Pacific Design Automation Conference 1999 (Cat. No.99EX198), 1999
We p r e s e n t a p p r o ximations to non-smooth continuous functions by di erentiable function... more We p r e s e n t a p p r o ximations to non-smooth continuous functions by di erentiable functions which are parameterized by a scalar 0 and have convenient limit behavior as ! 0. For standard numerical methods, this translates into a tradeo between solution quality and speed. We s h o w the utility o f our approximations for wirelength and delay estimations used by analytical placers for VLSI layout. Our approximations lead to more solvable" problems.
In this paper we investigate the multiplexing of heterogeneous applications and the pricing of tr... more In this paper we investigate the multiplexing of heterogeneous applications and the pricing of transmission services on an ATM network. Pricing is of interest for network management to promote efficient utilization of resources. A framework is presented in which users select from a menu of services, are peak-rate policed, and are charged according to their usage and connection time. We illustrate the considerable improvement in network utilization possible compared to a traditional
2019 American Control Conference (ACC), Jul 1, 2019
Standard economic dispatch problems that consider line losses are linear approximations of a non-... more Standard economic dispatch problems that consider line losses are linear approximations of a non-convex economic dispatch problem formulated by fixing voltage magnitudes and assuming the decoupling of real and reactive power. This paper formulates and analyzes the general non-convex economic dispatch problem, incorporating and generalizing the Fictitious Nodal Demand (FND) model, resulting in a slack bus independent formulation that provides insight into standard formulations by pointing out commonly used but unnecessary assumptions and by deriving proper choices of "tuning parameters." The proper choice of loss allocation is derived to assign half of the losses of each transmission line to adjacent buses, justifying approaches in the literature. Line constraints are proposed in the form of voltage angle difference limits and are proven equivalent to various other line limits including current magnitude limits and mid-line power flow limits. The formulated general economic dispatch problem with marginal losses consistently models flows and loss approximation, results in approximately correct outcomes and is proven to be reference bus independent. Various approximations of this problem are compared using realistically large transmission network test cases.
Optimal Data Attacks on Power Grids: Leveraging Detection & Measurement Jamming
Meter measurements in the power grid are susceptible to manipulation by adversaries, that can lea... more Meter measurements in the power grid are susceptible to manipulation by adversaries, that can lead to errors in state estimation. This paper presents a general framework to study attacks on state estimation by adversaries capable of injecting bad-data into measurements and further, of jamming their reception. Through these two techniques, a novel `detectable jamming' attack is designed that changes the state estimation despite failing bad-data detection checks. Compared to commonly studied `hidden' data attacks, these attacks have lower costs and a wider feasible operating region. It is shown that the entire domain of jamming costs can be divided into two regions, with distinct graph-cut based formulations for the design of the optimal attack. The most significant insight arising from this result is that the adversarial capability to jam measurements changes the optimal 'detectable jamming' attack design only if the jamming cost is less than half the cost of bad-data...
A Stochastic Transmission Planning Model With Dependent Load and Wind Forecasts
IEEE Transactions on Power Systems
This paper introduces a two-stage stochastic program for transmission planning. The model has two... more This paper introduces a two-stage stochastic program for transmission planning. The model has two dependent random variables, namely, total electric load and available wind power. Given univariate marginal distributions for these two random variables and their correlation coefficient, the joint distribution is modeled using a Gaussian copula. The optimal power flow (OPF) problem is solved based on the linearized direct current (DC) power flow. The Electric Reliability Council of Texas (ERCOT) network model and its load and wind data are used for a test case. A 95% confidence interval is formed on the optimality gap of candidate solutions obtained using a sample average approximation with 200 and 300 samples from the joint distribution of load and wind.
Spatial prediction of wind farm outputs using the Augmented Kriging-based Model
2012 IEEE Power and Energy Society General Meeting, 2012
ABSTRACT
Case study of an improved Cascading Outage Analysis model using outage checkers
2013 IEEE Power & Energy Society General Meeting, 2013
ABSTRACT
ECE Dept., Univ. of Texas at Austin, Austin, TX, USA
Robustified Reserve Modelling for Wind PowerIntegration in Ramp-Based Unit Commitment
In recent years, high penetration of variable generating sources, such as wind power, has challen... more In recent years, high penetration of variable generating sources, such as wind power, has challenged independent system operators (ISO) in keeping a cheap and reliable power system operation. Any deviation between expected and real wind production must be absorbed by the power system resources (reserves), which must be available and ready to be deployed in real time. To guarantee this resource availability, the system resources must be committed in advance, usually the day-ahead, by solving the so-called unit commitment (UC) problem. If the quantity of committed resources is extremely low, there will be devastating and costly consequences in the system, such as significant load shedding. On the other hand, if this quantity is extremely high, the system operation will be excessively expensive, mainly because facilities will not be fully exploited.This thesis proposes computationally efficient models for optimal day-ahead planning in (thermal) power systems to adequately face the stochastic nature of wind production in the real-time system operation. The models can support ISOs to face the new challenges in short-term planning as uncertainty increases dramatically due to the integration of variable generating resources. This thesis then tackles the UC problem in the following aspects: Power system representation: This thesis identifies drawbacks of the traditional energy-block scheduling approach, which make it unable to adequately prepare the power system to face deterministic and perfectly known events. To overcome those drawbacks, we propose the ramp-based scheduling approach that more accurately describes the system operation, thus better exploiting the system flexibility.UC computational performance: Developing more accurate models would be pointless if these models considerably increase the computational burden of the UC problem, which is already a complex integer and non-convex problem. We then devise simultaneously tight and compact formulations under the mixed-integer programming (MIP) approach. This simultaneous characteristic reinforces the convergence speed by reducing the search space (tightness) and simultaneously increasing the searching speed (compactness) with which solvers explore that reduced space.Uncertainty management in UC: By putting together the improvements in the previous two aspects, this thesis contributes to a better management of wind uncertainty in UC, even though these two aspects are in conflict and improving one often means harming the other. If compared with a traditional energy-block UC model under the stochastic (deterministic) paradigm, a stochastic (deterministic) ramp-based UC model: 1) leads to more economic operation, due to a better and more detailed system representation, while 2) being solved significantly faster, because the core of the model is built upon simultaneously tight and compact MIP formulations.To further improve the uncertainty management in the proposed ramp-based UC, we extend the formulation to a network-constrained UC with robust reserve modelling. Based on robust optimization insights, the UC solution guarantees feasibility for any realization of the uncertain wind production, within the considered uncertainty ranges. This final model remains as a pure linear MIP problem whose size does not depend on the uncertainty representation, thus avoiding the inherent computational complications of the stochastic and robust UCs commonly found in the literature.
Hidden Attacks on Power Grid: Optimal Attack Strategies and Mitigation
State estimation distributed processing [discussion and closure]
IEEE Transactions on Power Systems, 2001
J. Aguado and V. Quintana comment on the paper by R. Ebrahimian and R. Baldick (see ibid., vol.15... more J. Aguado and V. Quintana comment on the paper by R. Ebrahimian and R. Baldick (see ibid., vol.15, no.4, p.1240-6, 2000), and ask for comments on five points relating to their own work in this area of power network state estimation. The original authors reply to the comments
Coarse-grained distributed optimal power flow
IEEE Transactions on Power Systems, 1997
Dispatchable transmission in RTO markets
IEEE Transactions on Power Systems, 2005
We consider transmission owners that bid capacity, under appropriate Regional Transmission Organi... more We consider transmission owners that bid capacity, under appropriate Regional Transmission Organization (RTO) market rules, at a positive price into forward and spot (dispatch) auctions to derive congestion revenues. This can encompass daily, monthly, or multimonthly auctions, allowing for commitment of transmission to reflect market needs in different time periods, e.g., seasons. We provide two and three node examples and