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The paper applies the well-known red-green-blue (RGB) coloring method to visualize traveling waves initiated by switching events or faults occurring in power systems. The three-phase voltage profile along a given transmission line is obtained first. This profile is then converted into a colored picture by assigning different colors to phase signals according to their intensity. An interesting outcome of repeating this process for each time step is the emergence of the Bewley diagram [1] which is commonly used to illustrate the behavior of traveling waves in space-time. The main contribution of the paper is to show that RGB coloring of phase signals reveals essentially the same profile as the one obtained by using the aerial mode of the signals transformed into the modal domain. Furthermore, it discusses how this result can possibly be useful in applications such as fault location. [ABSTRACT FROM AUTHOR]

Conventional measurement and verification for non-interval metered, direct load control (DLC) programs bidding into wholesale electricity markets usually requires a PURPA-compliant load research study. This requirement con- tributes to high operating costs and has been a factor in recent reductions in the amount of emergency demand response available to regional transmission system operators. This paper describes. a collaborative effort by PJM members to determine whether regional modeling using pooled historical data could satisfy DLC measurement and verification (M&V) requirements without sacrificing estimation accuracy. This paper also describes how PJM incorporated the regional "deemed savings estimates" into its Load Data Systems Manual. This paper concludes that regional approaches to MଦV could yield large cost savings for DLC resource providers around the country. [ABSTRACT FROM AUTHOR]

In isolated power systems, frequency stability is traditionally considered to be assured by maintaining sufficient spinning reserve that is usually equal to the largest generation output of all the units in operation. However, the system security depends on the spinning reserve allocation to the units in operation and the provision of adequate emergency or fast reserve that need be available in the first crucial seconds after a loss of generation event. The system emergency reserve is usually much lower than that expected if only the unit droops are taken into account. Also, the generating units can be overloaded for a short time period and this capability can contribute to a faster frequency restoration. This paper presents an improved speed governor model that utilizes the short time overloading capability of the generating units. The efficient computational method described in the paper for the optimal spinning reserve allocation in isolated power systems was developed by taking into account a composite security criterion in the most economic way. Furthermore, a statistical analysis is presented in order to investigate the contribution of spinning reserve to the short-term system security. In the paper the developed method is applied to a typical isolated power system and it demonstrates its advantages. [ABSTRACT FROM AUTHOR]

This paper analyzes the behavior of Hong's point estimate methods to account for uncertainties on the probabilistic power flow problem. This uncertainty may arise from different sources as load demand or generation unit outages. Point estimate methods constitute a remarkable tool to handle stochastic power system problems because good results can be achieved by using the same routines as those corresponding to deterministic problems, while keeping low the computational burden. In previous works related to power systems, only the two-point estimate method has been considered. In this paper, four different Hong's point estimate schemes are presented and tested on the probabilistic power flow problem. Binomial and normal distributions are used to model input random variables. Results for two different case studies, based on the IEEE 14-bus and IEEE 118-bus test systems, respectively, are presented and compared against those obtained from the Monte Carlo simulation. Particularly, this paper shows that the use of the 2m + 1 scheme provides the best performance when a high number of random variables, both continuous and discrete, are considered. [ABSTRACT FROM AUTHOR]

High-temperature low-sag (HTLS) conductors, which can double the ampacity of conventional conductors, are becoming a mature option to uprate thermally limited transmission lines. This paper addresses several issues related to the widespread use of HTLS conductors in existing power systems. The first part of the paper analyzes the influence of higher line resistances on power transfer capability as well as the accuracy of conventional network models, based on constant conductor temperatures. The second part deals with the problem planners are facing when considering existing network reinforcement options versus the new alternative offered by HTLS conductors, intended to replace Alloy Aluminum Conductor Steel Reinforced (ACSR) equipment in situ. This leads to a security-constrained optimization problem involving binary decision variables. The 57-bus system is used throughout the paper to illustrate the main ideas. [ABSTRACT FROM AUTHOR]

In this paper, the authors propose a fuzzy-optimization approach to dynamic economic dispatch, considering the uncertainties in deregulated energy and reserve markets. The methodology was developed from the viewpoint of a generation company wishing to maximize its own profit and to hedge its risks as a participant In the energy market and 10-min spinning reserve market. The uncertainties in the current paper were represented with fuzzy numbers, and consist of the demand and reserves required In each market, prices cleared in each market, and the probability that reserves are called upon in actual operation. The energy and reserve markets were coordinated by the generator ramp rate limits. The optimal amounts of power. and reserve were determined by solving the optimization problem. Two reserve payment methods, payment for power delivered and payment for reserve allocated, were Investigated in this paper. [ABSTRACT FROM AUTHOR]

This is a follow-on paper to "A New Thermal¹ Governor Modeling Approach in the WECC²" [1]. The paper describes the steps being taken to obtain validated data for the new governor models. It was recognized that the developmental database [1] that was created to prove the new thermal governor model should not be used to perform operation or planning studies. Invalid governor data for real-lime operation simulations gives rise to risks and liabilities in the determination of intertie limits. Due to the large number of governors involved (about 1100 units) and the short timeline for obtaining data in critical 2003 summer operation studies, a concerted effort is being made to assist generator owners to select and validate the appropriate governor model codes for their units. This effort includes a workshop and the issue of detailed guidelines aid validation methodologies for governor modeling. [ABSTRACT FROM AUTHOR]

This paper proposes a method to evaluate the ATC by considering dynamic constraints. The paper adopts equilibrium equations to describe steady-state constraints of pre and postdisturbance. Dot product is used as a criterion for rotor angle stability. An algorithm based on control variable parameterization (CVP) is implemented to solve the formulated dynamic-constrained optimization (DCO) problem. A nine-bus three-machine system is used to illustrate the proposed model and algorithm. [ABSTRACT FROM AUTHOR]

This paper presents a new methodology for allocating transmission system costs in single or interconnected energy markets. Initially, the proposed method allows the decomposition of the total transmission cost into two components: the first corresponds to the utilized network capacity, estimated at a specified operating condition, and the second refers to the transmission capacity available but not used in the system. A technique for decomposing nodal tariffs per subsystem guarantees the applicability of the method to interconnected markets. From the proposed procedure, it is possible to determine the responsibility of each participant (or group of participants) in the use of any specified set of transmission elements. The flexibility of this method allows the establishment of criteria based on economic and technical aspects for cost allocation of internal circuits of each subsystem, as well as of the tie elements between the subsystems. Important characteristics of the proposed methodology, such as transparency, impartiality, and flexibility, are analyzed and illustrated based on numerical applications with the IEEE Reliability Test System. Experience with the Brazilian transmission network is also discussed. [ABSTRACT FROM PUBLISHER]

This paper presents the approach elaborated by Hydro-Quebec TransEnergie (Hydro-Quebec's transmission division) in collaboration with Hydro-Quebec's Research Institute (IREQ) to improve the dynamic transfer limits of its transmission system in the coming years. The evaluation of these limits is mainly related to transient and voltage stability problems. As the complexity of the network increases, so does the number of studies required to determine transfer limits. The proposed approach provides an integrated process for power system operation planning engineers to establish secure transfer limits in a shorter lead time. These limits are optimized for specific power system configurations under constrained operating conditions. Faster and more rigorous methods have been developed in the integrated process. [ABSTRACT FROM AUTHOR]

Power system oscillatory behavior can be analyzed in terms of modes, expressed as exponentially modulated sinusoids, exhibited in signals measured on the system. These signals are driven by the behavior of a large, nonlinear, time-variant system. In this paper, two modal identification methods are examined comparatively: Prony analysis and a method based on the Hilbert transform. Considerable structural differences exist between the two methods. Prony analysis yields modes which are directly expressed as exponentially modulated sinusoids, whereas the Hilbert method provides a more general solution. Synthetic and measured signals are used in the comparison. Some general conclusions are drawn from the analysis of several signals, including two sets of measured field data. [ABSTRACT FROM AUTHOR]

Price forecasting in competitive electricity markets is critical for consumers and producers in planning their operations and managing their price risk, and it also plays a key role in the economic optimization of the electric energy industry. This paper explores a technique of artificial neural network (ANN) model based on similar days (SD) method in order to forecast day-ahead electricity price in the PJM market. To demonstrate the superiority of the proposed model, publicly available data acquired from the PJM Interconnection were used for training and testing the ANN. The factors impacting the electricity price forecasting, including time factors, load factors, and historical price factors, are discussed. Comparison of forecasting performance of the proposed ANN model with that of forecasts obtained from similar days method is presented. Daily and weekly mean absolute percentage error (MAPE) of reasonably small value and forecast mean square error (FMSE) of less than 7$/MWh were obtained for the PJM data, which has correlation coefficient of determination (R²) of 0.6744 between load and electricity price. Simulation results show that the proposed ANN model based on similar days method is capable of forecasting locational marginal price (LMP) in the PJM market efficiently and accurately. [ABSTRACT FROM AUTHOR]

The optimal power flow issue is one of the most important problems faced by dispatching engineers regarding large scale power systems. It is a particular mathematical approach of the global power system optimization problem that aims at determining the least control movements to keep power system at the most desired state. Thus, it represents a flexible and powerful tool, which can address a wide range of planning and operation studies. However, the complexity of optimal power flow increases dramatically with large-scale networks, which often discourages the utilization of this powerful tool in many applications. This paper proposes a new intelligent approach to facilitate the implementation of the optimal power flow calculations to be utilized in various control centres. A main advantage of the proposed intelligent systems with real control centres is the possibility of controlling the system voltage profile in a tracking mode. The simulation results using this intelligent system when applied to the IEEE 30-bus power network emphasize the validity and effectiveness of the proposed technique. [ABSTRACT FROM AUTHOR]

If transmission charges are to reflect costs, they should be affected by the location of demand and generation. This paper describes the investment cost-related pricing (ICRP) methodology used to calculate transmission charges in Great Britain (GB), which is based on the marginal investment cost of additional demand or generation, using a dc load flow transport model. We apply this existing method to calculate charges for the Supergen FutureNet scenarios for 2020. This study highlights the sensitivities in charges for use of the transmission system arising from plausible demand and generation developments. The changes in tariffs will present financial challenges for system users in some areas. The objective of the work presented is to illustrate the sensitivity of the charges produced by this methodology to changes in demand, generation, and network topology rather than compare alternative pricing approaches. The conclusion drawn is that the ICRP system pricing method may be suitable in future years but only with some important issues investigated and resolved. [ABSTRACT FROM AUTHOR]

Parties to the Internal Electricity Market of the European Union (IEM) decided in 2001 to abolish the method of pan-caking of transmission tariffs for cross-border transactions that was originally in place. Instead, they have agreed to implement a system whereby national transmission tariffs provide access to the entire IEM. This system is supplemented by a scheme of inter-TSO payments. However, conflict may arise if the compensation that a country must pay another one is not in accordance with the electrical usage that the former is making of the grid of the latter. For instance, Inter TSO Compensation methods (ITC methods) implicitly allocate the cost of any existing or new transmission line. Therefore, the adoption of an inefficient method may be an obstacle for building some needed regional grid investments. Consequently, one should give careful consideration to the selection of the ITC method. This paper analyzes, both qualitatively and quantitatively, the implementation of the most relevant ITC methods that have been considered so far in the European debate. When assessing each method from a conceptual point of view, considerable attention is devoted to the critical examination of its main underlying assumptions. [ABSTRACT FROM AUTHOR]

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 long-term 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. [ABSTRACT FROM AUTHOR]

From an economic perspective, a common criterion for assessing the merits of a transmission investment is its impacts on social welfare. The underlying assumption in using this criterion is that side payments may be used to distribute the social gains among all market players. In reality, however, since the impacts of an electricity transmission project on different players may vary, such side payments are rather difficult to implement. This paper focuses on different economic criteria that should be considered when planning electricity transmission investments. We propose an electricity transmission investment assessment methodology that is capable of evaluating the economic impacts on the various effected stakeholders and account for strategic responses that could enhance or impede the investment's objectives. We formulate transmission planning as an optimization problem under alternative conflicting objectives and investigate the policy implications of divergent expansion plans resulting from the planner's level of anticipation of strategic responses. We find that optimal transmission expansion plans may be very sensitive to supply and demand parameters. We also show that the transmission investments have significant distributional impact, creating acute conflicts of interests among market participants. We use a 32-bus representation of the main Chilean grid to illustrate our results. [ABSTRACT FROM AUTHOR]

This paper presents an optimum power flow (OPF) modeling algorithm that uses the primal-dual interior point technique to determine the best investment strategy in the transmission line expansion problem. In the proposed method, the expansion decision (0 or 1) is mitigated by using a sigmoid function, which is incorporated in the OPF problem through the modified dc power flow equations. The investment decision is taken using a new heuristic model based on good sensitivity produced by the OPF results. Additionally, the transmission power losses are considered in the network model. The proposed methodology has been compared with methods available in the literature, using both a test system and an equivalent of the southeastern Brazilian system. [ABSTRACT FROM AUTHOR]

Ramp rates of generators are. generally specified within elastic range of the strength of the shaft to safeguard the rotor from fatigue. These limits can, however, be exceeded, albeit at the risk of reducing the rotor life. Such effects on the rotor life can be compensated by incorporating appropriate ramping costs. Power demand and power price in deregulated power markets have shown a tendency of sudden wide excursions over short intervals of time. The ability to respond to such fast change in demand and price can be quite rewarding. This provides the motivation to utilize the ramping rates beyond traditional elastic limits. This paper studies the strategic use of ramping rates beyond elastic limits in a power producer's self-dispatch in a power market with price and demand volatility A set of ramping processes has been developed. from ramping-cost versus ramping time relationships to derive the total operation cost including ramping costs for various levels of ramping rates exceeding elastic limits. A thorough theoretical analysis has been conducted for the selection of the optimal ramping process under different conditions. A numerical example is presented to highlight the potential benefits from the optimal use of these ramping processes. It is seen that the benefit from the strategic use of lamp rates beyond elastic limits not only depends on the high price in the power market hut also on the initial loading of the generator which limits the capacity available for dispatch. [ABSTRACT FROM AUTHOR]

In this paper, a structure preserving energy margin (EM) sensitivity-based analysis is presented to determine the amount of preventive generation rescheduling to stabilize a transiently unstable power system. An expression using a simplified model Is derived to relate the change in the EM to change in generation. Utilising this expression, two approaches for generation rescheduling are developed which are applicable to detailed model of power systems. The proposed methods are applied to the 10-machine New England power system and 16-machine power system with detailed power system models. [ABSTRACT FROM AUTHOR]

Electric power systems are increasingly involved in the competitive electrical energy market where several Players have access to the transmission networks even though in a regulated way. The purpose of this paper is to present an improved computational method and the associated computer program RACTRS that can be used for the reliability and cost analysis of power transmission networks that accommodate transmission transactions. This is a method that is based on a Monte-Carlo sequential simulation approach and gives an increased emphasis in the realistic and efficient representation of the real design and operational characteristics and practices applied by the electric utilities today. For this purpose, the operating aspects of wheeling transactions are integrated into the developed method together with a technique for tracing the power flows through the meshed transmission networks, An extended set of appropriate reliability and cost indices is calculated for each load-point of interest, the entire system and each wheeling transaction under consideration. The analysis of a system based on the IEEE-RTS is also included for a number of studies representing the various operating and design characteristics. [ABSTRACT FROM AUTHOR]

In a new competitive environment, it becomes possible for third parties to access transmission networks. Key information used to determine how much power can be transferred through the network is known as available transfer capability (ATC). Generally, ATC is calculated based on the severest case with some safety margin reserved for any uncertainty in the near future. However, without considering the probabilistic nature of the power system, it becomes a question whether ATC is reasonable in practice or not. This paper proposes a probabilistic approach to cope with this problem. By the probabilistic method, a characteristic of the transfer capability can be obtained through its probability density function. The objective of this research is to provide realistic information on the actual ability of the network that may be an alternative choice for system operators. The advantages of this proposed method are illustrated by an application to a modified IEEE 118-bus system. [ABSTRACT FROM AUTHOR]

This paper presents a methodology to determine a rational among the electric energy market information, the total transfer capability (TTC) in the transmission system and the estimation of random equipment failures. The proposed approach includes the models of unavailability due to both repairable and aging failures of equipment, the calculation method of two discrete statistical distributions representing energy prices and export powers, and a probabilistic benefit/cost analysis technique. An actual example of 500-kV reactors at British Columbia Transmission Corporation (BCTC) has been given to demonstrate the procedure of the application. The results indicate that the redundancy level determined using this approach not only enables the utility to avoid possible losses in the income from energy sales and improves the profile of system TTC but also guarantees a high benefit/cost ratio in a financial justification of redundant equipment addition. [ABSTRACT FROM AUTHOR]

The capability to deal effectively with the uncertainty associated with locational marginal prices (LMPs) in congestion management schemes requires the development of appropriate financial tools. Congestion revenue rights (CRR) are hedging tools that provide the holder reimbursement of the congestion charges in the day-ahead market and thereby provide transmission service customers with price certainty. In this paper, we construct a framework for the design and analysis of the CRR by marrying finance theory notions with salient characteristics of electric power systems and electricity markets. The framework consists of three interconnected layers with one layer each to represent the model of the transmission network, the commodity markets and the CRR financial markets. The interaction between the layers is represented as information flows. The framework has sufficient cope to allow the analysis of a broad range of problems associated with ensuring price certainty for transmission services. The structural modularity of the framework provides the flexibility to analyze issues and design structures for the provision of transmission services in the competitive environment. We introduce a new notion of CRR payoff parity and a practical pricing scheme, which are used as the basis for the design of more liquid CRR markets. The application of the framework is further illustrated by the analysis of the conditions that guarantee the revenue adequacy for the CRR issuer. [ABSTRACT FROM AUTHOR]