perishable inventory theory a review this paper reviews the relevant literature on the problem of determining suitable ordering policies for both fixed life perishable inventory and inventory subject to continuous exponential decay we consider both deterministic and stochastic demand for single and multiple products both optimal and sub optimal order policies are discussed in addition a brief review of the application of these models to blood bank management is included the review concludes with a discussion of some of the interesting open research questions in the area

pricing and lot sizing decisions for perishable goods when demand depends on selling price reference price product freshness and displayed stocks abstract price is an important factor affecting demand rate based on economic and marketing theory in addition today s health conscious consumers prefer a product further from its expiration date because it is fresher and can be stored longer furthermore a large display of goods in a supermarket induces customers to buy more due to its visibility variety and seasonality as a result we develop a joint pricing and lot sizing model for retailers selling perishable products in which the demand depends on not only the selling price and reference price but also the product freshness linked to expiration date and displayed stock level we then formulate the problem as a deterministic model in which the retailer determines the optimal selling prices and ending inventory levels to maximize the discounted total profit furthermore we discuss the retailer s optimal decisions under two scenarios of demand behavior loss neutrality and loss aversion our theoretical analysis shows that the optimal pricing and ending inventory level strategies are both monotonic in time and the equilibrium of the system is unique for these two scenarios of demand behavior finally a set of structural properties and sensitivity analysis is also developed to characterize the impacts of model parameters on the optimal decisions

pricing and lot sizing polices for perishable goods when the demand depends on selling price displayed stocks and expiration date abstract price is a major factor on the demand based on marketing and economic theory in addition the demand for perishable products also depends on its freshness moreover it is a well known fact that increasing stock display e g fresh fruits vegetables baked goods may encourage consumers to purchase more this paper first proposes an inventory model that stipulates the demand explicitly in a multivariate function of price freshness and displayed stocks it may be profitable to have a closeout sale at a markdown price and always keep on hand displayed stocks fresh and plentiful if the demand is freshness and stock dependent hence the traditional assumption of zero ending inventories is relaxed to a non zero ending inventory as a result the objective is to determine three decision variables i e unit price cycle time and ending inventory level in order to maximize the total profit then it is demonstrated that the total profit is strictly pseudo concave in those three decision variables which reduces the search for solutions to a unique local maximum finally numerical examples to illustrate the theoretical results and to highlight managerial insights are presented

market clearing with stochastic security part i formulation the first of this two paper series formulates a stochastic security constrained multi period electricity market clearing problem with unit commitment the stochastic security criterion accounts for a pre selected set of random generator and line outages with known historical failure rates and involuntary load shedding as optimization variables unlike the classical deterministic reserve constrained unit commitment here the reserve services are determined by economically penalizing the operation of the market by the expected load not served the proposed formulation is a stochastic programming problem that optimizes concurrently with the pre contingency social welfare the expected operating costs associated with the deployment of the reserves following the contingencies this stochastic programming formulation is solved in the second companion paper using mixed integer linear programming methods two cases are presented a small transmission constrained three bus network scheduled over a horizon of four hours and the ieee reliability test system scheduled over 24 h the impact on the resulting generation and reserve schedules of transmission constraints and generation ramp limits of demand side reserve of the value of load not served and of the constitution of the pre selected set of contingencies are assessed

optimization based approach for price multiplicity in network constrained electricity markets this paper addresses the problem of price multiplicity in network constrained pool based electricity markets under marginal pricing this problem consists in the existence of multiple vectors of locational marginal prices for the same optimal market clearing dispatch solution as a consequence delicate conflicts of interest may arise among market participants price multiplicity may take place even in auction designs based on convex formulations for the market clearing procedure an effective duality based solution approach is proposed in this paper to handle the issue of price multiplicity once the optimal market clearing dispatch is known we propose the subsequent solution of a simple pricing problem in order to determine the vector of locational marginal prices unlike previously reported methodologies the proposed approach presents two salient features 1 it is based on sound mathematical programming and 2 it is computationally inexpensive since it relies on the solution of a linear program numerical results are provided to illustrate the performance of the proposed tool

min max regret bidding strategy for thermal generator considering price uncertainty the electricity price volatility brings challenges to bidding strategies in the electricity markets in this paper we propose a minimax regret approach for a market participant to obtain an optimal bidding strategy and the corresponding self scheduled generation plans motivated by recently proposed robust optimization approaches our approach relies on the confidence intervals of price forecasts rather than point estimators we reformulate the minimax regret model as a mixed integer linear program milp and solve it by the benders decomposition algorithm moreover we design a bidding strategy based on the price forecast confidence intervals to generate the offer curve finally we numerically test the minimax regret approach in comparison with the robust optimization approach on three types of thermal generators by using real electricity price data from pjm to verify the effectiveness of our proposed approach

market clearing with stochastic security part ii case studies this paper analyzes the market clearing formulation with stochastic security developed in its companion paper through two case studies solved using mixed integer linear programming techniques the generation and reserve schedules as well as the nodal prices of energy and security are assessed under various conditions such as a line flow limits b when nonspinning reserve is excluded from the formulation c demand side valuation of energy not served d generator ramping limits and e the set of pre selected contingencies

two stage stochastic programming model for market clearing with contingencies planning for contingencies typically results in the use of more expensive facilities before disruptions it leads to different prices and energy availability at various network locations depending on how the contingency analysis is performed in this paper we present a two stage stochastic programming model for incorporating contingencies the model is computationally demanding and made tractable by using an interior point log barrier method coupled with benders decomposition the second stage optimal recourse function rf defines the most economically efficient actions in the post contingency state for returning the system back to normal operating conditions the approach is illustrated with for two examples small with 8 buses 11 branches and ieee medium scale with 300 buses 411 branches

advanced pricing in electrical systems i theory this paper sets forth a comprehensive theory for the real time pricing of electricity that includes selected ancillary services and extends the theory to incorporate constraints on power quality and environment impact that often influence the operation of a power system this paper is part i of a two paper set it sets forth the mathematical development of the extended model for real time pricing the formulation is novel in that it combines the dynamic equations for load frequency control with the static equations of a constrained optimal power flow part ii derives optimal nodal specific real time prices for both real and reactive power the prices derived include additive premia or opportunity costs reflecting the effects of voltage regulation maintenance of generation and transmission reserves regulation of frequency and tie line flows removal and or control of power harmonics and others

evolution toward standardized market design the evolution toward the standardized market design smd is presented in this paper with references to the market developments in new zealand australia pjm iso ne and ercot in the development of market designs two main objectives market liquidity facilitating bilateral trading and pricing efficiency facilitating congestion management have been pursued the efforts to balance the seemingly conflicting objectives led to most markets designed with a uniform or zonal pricing model introduction of locational marginal pricing and evolution of transmission rights from physical to financial form made it possible to harmonize the potentially conflicting goals in a market design the close coupling between energy and ancillary services requires that markets for these commodities be carefully coordinated different operational practices and reliability standard requirements have led to major differences in ancillary service market designs

a comprehensive assessment of the evolution of financial transmission rights financial transmission rights ftrs are complementary to the locational marginal pricing of energy the basic aim of the ftr mechanism is to guard forward contracts from uncertain congestion charges ftrs are also useful to individual generators and loads for selling and buying power respectively at the prices of other locations the concept has evolved encompassing many features such as a simultaneous feasibility test various ways to conduct auctions and allocations and secondary trading ftrs also have a close relation to market power and transmission investment this paper reviews most of the landmark research papers on the evolution of the ftr concept it reports a comprehensive assessment of various facets of ftrs and allied issues financial transmission rights and flowgate rights fgrs are compared the concept of long term ftrs is discussed the paper also touches upon future proposals in this area

low income homeownership american dream or delusion summary this paper is a critical analysis of recent us policy to promote low income homeownership it examines the ideology and assumptions buttressing this policy evidence on the effects of low income homeownership and the viability of homeownership as a strategy for low income families evidence suggests that the prospect for sustained growth in low income homeownership may be limited research does not provide uniform support for it as a tool for asset accumulation neighbourhood economic development or other social and political goals alleged effects of homeownership may be artefacts of self selection and the conflation of homeownership with unobserved characteristics coincident with buying homes what homeownership does and why are not well understood because of difficulties disentangling what homeownership means the elevation of low income homeownership to its current status has deflected political attention away from alternative policies for affordable housing

dcopf based marginal loss pricing with enhanced power flow accuracy by using matrix loss distribution on current days many of the power markets are adopting the practice of marginal loss pricing the dc optimal power flow dcopf model is still mostly used for the purpose of market clearing owing to its simplicity robustness and higher speed of convergence within the dcopf framework transmission line losses are represented as additional external loads on the system in the classical dcopf model of marginal loss pricing as implemented in the new england market the aggregated network loss is distributed over the system nodes in a fixed ratio to gain more design flexibility in the distribution of system losses a matrix loss distribution mld framework is developed in this paper maintaining compatibility with financial transmission rights in mld each individual line is considered separately for the purpose of loss distribution the ratio in which the power loss in a certain line is distributed can be different from that in which the power loss in another line is distributed the additional design flexibility thus obtained assists in making a more accurate representation of the power flow the benefit of mld is illustrated through a case study an energy reference independent application of mld is also suggested

locational marginal price sensitivities within an optimal power flow market clearing framework this paper provides expressions to compute the sensitivities of locational marginal prices with respect to power demands sensitivities with respect to other parameters can also be obtained an example and a case study are used to illustrate the expressions derived

eoq models for continuously deteriorating products using linear and exponential penalty costs abstract we present eoq models for perishable products which consider continuous deterioration of the utility of a product and introduce an exponential penalty cost function as a measurement of the utility deterioration the approach proposed is simple and can be used to obtain easily the closed forms of the economic order quantities which have not previously been derived these forms describe the effect of the penalty cost clearly and are a natural extension of economic order quantities for non perishable products our results are shown to be consistent with reported eoq models with exponential decay but derived more elaborately our approach has the added advantage that it can be easily extended to the economic lot scheduling problem for multi item perishable products

running a more complete market with the slp iv acopf the acopf is at the core of competitive electricity market design it is the only ac based algorithm that simultaneously co optimizes real and reactive power dispatch for steady state operations on ac power systems in practice independent system operators isos oversimplify the physical problem and settle the markets on locational marginal price lmps based on real power but do not price reactive power dispatch or voltage control this work proposes a market dispatch and pricing procedure based on the acopf to provide a more complete pricing mechanism we formulate the dual problem of the slp iv acopf as shown in 1 which is a successive linear program shown to solve the acopf to an acceptable quality of convergence to a best known solution with linear scaling of computational time in proportion to network size therefore the dual problem is also a linear program as a result the marginal value pricing of the optimal solution to the dual problem supports the market dispatch due to strong duality i e this solution technique results in a revenue adequate and more complete market design furthermore we show how to distribute the complete real time market settlements the analysis includes a direct comparison to dcopf based approaches similar to those applied in current iso markets

convexity of the set of feasible injections and revenue adequacy in ftr markets the feasible set of power injections for the constrained power flow equations is nonconvex when practical transmission capacity and bus voltage limits are imposed the projection onto the space of active power injections may be close to convex but this is not sufficient to guarantee revenue adequacy for the settlement of financial transmission rights

a security constrained bid clearing system for the new zealand wholesale electricity market this paper reports upon the mathematical models and implementation of the scheduling pricing and dispatch spd application for the new zealand electricity market nzem spd analyzes bids for energy offers reserve offers and energy demands and recognizes explicitly the effects on bid clearing due to transmission congestion network losses reserve requirements and ramp rate limits advanced lp solution methods are utilized to solve the large scale constrained optimization problem results on a 67 bus test system and the nzem are included

the effect of contingency analysis on the nodal prices in the day ahead market we look at the effect of modeling branch outage contingencies on locational marginal prices to model contingencies in the day ahead auction we formulate a two stage stochastic program rather than follow the current practice of including a list of possible contingencies that must be satisfied we incorporate a larger set of contingencies in the model and allow contingencies to result in load reductions outages at a cost the model can be used and interpreted in two ways one is to look at the tradeoff between reliability and outage costs another is to consider the load losses resulting from a contingency to be consumer offers of load reductions in response to line outages as part of the day ahead auction in analyzing the model structure we find that the prices in the model closer in definition to those currently used in the day ahead auction do not maximize expected surplus because the day ahead auction produces prices that assume shortages will never occur this raises issues with the design of auctions with important stochastic elements in the market we present results for a 68 node grid with 86 branches lines and transformers to illustrate how prices and expected values change as the costs of outages are varied

pricing energy and ancillary services in integrated market systems by an optimal power flow a detailed ac opf based formulation for procuring pricing and settling energy and ancillary service in simultaneous auctions by integrated market systems is presented the paper provides clear definitions of locational marginal prices for energy and ancillary service marginal prices in terms of lagrange multipliers the characteristics of the prices are analyzed especially when economic substitution among ancillary services is required the paper also evaluates the conditions under which opportunity costs are incurred to units that provide ancillary services it is particularly shown that the intuitive belief that the provision of regulation down service does not incur opportunity cost to the provider in general is not true

energy and reserve pricing in security and network constrained electricity markets this paper analyzes some unresolved pricing issues in security constrained electricity markets subject to transmission flow limits although the notion of separate reserve types as proposed by ferc can be precisely and unambiguously defined when transmission constraints are active the very existence of separate reserve prices and markets is open to question when the prices are based on marginal costs instead we submit here that the only products whose marginal costs can be separately and uniquely defined and calculated are those of energy and security at each node thus under marginal pricing at any given network bus all scheduled reserve types should be priced not at separate rates but at a common rate equal to the marginal cost of security at that bus furthermore we argue that nodal or area reserves cannot be prespecified but must be obtained as by products of the market clearing process simulations back up these conclusions

relative income effects on subjective well being in the cross section abstract recent work suggests that a person s subjective well being swb depends to a large degree on relative income focusing on the underlying identification this paper makes four contributions to this literature it describes the aggregation problem with past studies implements an estimation strategy to overcome this problem finds micro level evidence in support of the hypothesis that relative income does matter in individual assessments of swb and uses cross section estimates to replicate the aggregate time series the evidence further indicates that relative income effects may be smaller at low income levels the results are obtained from ordered probit techniques and the general social survey gss

market implications and pricing of dynamic reserve policies for systems with renewables static reserve policies are used within security constrained unit commitment scuc and security constrained economic dispatch sced to ensure reliability a common policy is that 10 min reserve must exceed the largest contingency however this condition does not guarantee reliability because voltage and thermal limits can hinder reserve deliverability many operators use zonal reserve markets to ensure reserves are dispersed across the grid such zonal models attempt to anticipate transmission bottlenecks which is a difficult task when the future system state is uncertain this paper examines the market implications of dynamic reserve policies used to mitigate uncertainty from renewable resources and contingencies we study the market implications of policies recently proposed in the literature such as hourly zones within day ahead scuc and an algorithm that formally disqualifies reserves that are expected to be undeliverable a locational reserve pricing scheme is also proposed in connection with scenario based reserve disqualification analysis on the rts 96 test case shows that dynamic zones and reserve disqualification along with the proposed compensation scheme help direct reserve payments toward resources that more effectively respond to contingencies

is more always better a survey on positional concerns abstract we use survey data to provide some empirical information about concerns regarding relative standing respondents chose between a world where they have more of a good than others and one where everyone s endowment of the good is higher but the respondent has less than others questions asked about education attractiveness and intelligence for one s child and oneself income vacation time approval and disapproval from a supervisor and papers to write half of the respondents preferred to have 50 less real income but high relative income concerns about position were strongest for attractiveness and supervisor s praise and weakest for vacation time

risk based locational marginal pricing and congestion management this paper develops a new electricity market clearing mechanism called risk based locational marginal pricing rlmp the rlmp is derived from the risk based security constrained economic dispatch model where risk is modeled to capture the system s overall security level compared to the traditional locational marginal pricing lmp which is composed of three components energy congestion and loss the rlmp consists of an additional risk component the risk component is a price signal to reflect the system s overall security level this paper discusses the features of rlmp and analyzes its benefits over traditional lmps the proposed concept and method are illustrated on a six bus system and the wecc 240 bus system

advanced pricing in electrical systems ii implications part i of this paper set forth a mathematical formulation of a model for real time pricing of electricity that included selected ancillary services and extended the theory to incorporate constraints on power quality and environment impact that often influence the operation of a power system derived herein are optimal real time prices for both real and reactive power the optimal prices are temporally and spatially differentiated the prices derived include additive premia or opportunity costs reflecting the effects of voltage regulation maintenance of generation and transmission reserves regulation of frequency and tie line flows removal and or control of power harmonics and others this paper concludes with a discussion of the implications of the optimal prices for pricing of both retail and wholesale services

a penalty scheme for reducing electricity price volatility the deregulation of electric power systems in many parts of the world has changed the mechanism of electricity pricing unlike the fixed price in conventional power systems electricity price varies with time and location in the new deregulated environment electricity prices in a restructured power system can be highly volatile due to the random nature of system failures and demands it is therefore very difficult for the independent system operator iso to control the price and associated risk the high prices beyond control have resulted in significant impacts on customers as well as on system operation this paper proposes a penalty scheme for reducing electricity price volatility caused by failures in generation companies gencos or transmission companies transcos in this scheme gencos and transcos will be penalized if their equipment failures result in unexpected price changes the price decomposition technique is used to evaluate the price components caused by random failures the penalty can be calculated based on the difference of electricity price components between the normal state and the contingency states moreover a simplified schema which is based on profit analysis is also proposed in this paper the proposed penalty scheme not only gives the gencos and transcos an incentive to improve their reliabilities but also provides a flexible tool for the iso to control the system price risk the possible shortcomings of the proposed schema are also specified in the paper the ieee rts is analyzed to illustrate the technique

strong formulations for multistage stochastic self scheduling unit commitment with the increasing penetration of renewable energy into the power grid system the volatility of real time electricity prices increases significantly this brings challenges for independent power producers to provide optimal bidding strategies the traditional approaches of only attending the day ahead market might not be profitable enough without taking advantage of real time price volatility in this paper we study the optimal bidding strategies for the independent power producers utilizing self scheduling strategies to participate in the real time market considering real time electricity price volatility with the objective of maximizing the total expected profit considering the correlations of renewable energy generation outputs among different time periods the correlations of real time prices are captured in our modeling framework in which we explore a multistage stochastic scenario tree to formulate the price uncertainties accordingly the derived multistage stochastic self scheduling unit com

an eoq model with ramp type demand rate time dependent deterioration rate unit production cost and shortages an order level inventory system for deteriorating items has been developed with demand rate as a ramp type function of time the finite production rate is proportional to the demand rate and deterioration rate is time proportional the unit production cost is inversely proportional to the demand rate the model with no shortage case in inventory is first solved the inventory shortage is discussed next results are illustrated with two numerical examples for two models along with its sensitivity

home ownership as a social norm and positional good subjective wellbeing evidence from panel data much attention has been devoted to examining the absolute benefits of home ownership e g security and autonomy this paper by contrast is concerned with conceptualising and testing the relative benefits of home ownership those benefits that depend on an individual s status in society home ownership has previously been analysed as a social norm implying that the relative benefits costs associated with being an owner renter are positively related to relevant others home ownership values the theoretical contribution of this paper is to additionally conceptualise home ownership as a positional good implying that the status of both home owners and renters is negatively related to relevant others home ownership consumption the empirical contribution of this paper is to quantitatively test for these relative benefits in terms of subjective wellbeing we run fixed effects regressions on three waves of the british household panel study we find that 1 a strengthening of relevant others home ownership values is associated with increases decreases in the subjective wellbeing of home owners renters and 2 an increase in relevant others home ownership consumption decreases the life satisfaction of owners but has no effect for renters overall our findings suggest that 1 the relative benefits of home ownership are both statistically significant and of a meaningful magnitude and 2 home ownership is likely to be both a social norm and a positional good without explicitly recognising these relative benefits policymakers risk overestimating the contribution of home ownership to societal wellbeing

an oligopolistic power market model with tradable no sub x permits models formulated as complementarity problems have been applied previously to assess the potential for market power in transmission constrained electricity markets here we use the complementarity approach to simulate the interaction of pollution permit markets with electricity markets considering forward contracts and the operating reserve market because some power producers are relatively large consumers of permits there could be interaction between market power in the permits and energy markets market power in the energy market is modeled using a cournot game while a conjectured price response model is used in the permits market an illustrative application is made to pennsylvania new jersey maryland interconnection pjm which we represent by a 14 node dc load flow model and the usepa ozone transport commission no sub x budget program the results show that forward contracts effectively mitigate market power in pjm energy market and both simulated solutions of perfect and cournot oligopoly competition are a good approximation to actual prices in 2000 except that the cournot model yielded higher peak prices the no sub x market influences the cournot energy market in several ways one is that cournot competition lowers the price of no sub x permits which in turn affects on low and high emission producers differently in general because pollution permits are an important cost high concentration in the market for such permits can exacerbate the effects of market power in energy markets

spot pricing when lagrange multipliers are not unique classical spot pricing theory is based on multipliers of the primal problem of an optimal market dispatch i e the solution of the dual problem however the dual problem of market dispatch may yield multiple solutions in these circumstances spot pricing or any standard pricing practice based on multipliers cannot generate a unique clearing price although such situations are rare they can cause significant uncertainties and complexities in market dispatch in practice this situation is solved through simple empirical methods which may cause additional operations or biased allocation based on a strict extension of the principles of spot pricing and surplus allocation we propose a new pricing methodology that can yield unique impartial and robust solution the new method has been analyzed and compared with other pricing approaches in accordance with spot pricing theory case studies support the results of the theoretical analysis and further demonstrate that the method performs effectively in both uniform pricing and nodal pricing markets

the social and private micro level consequences of homeownership abstract this paper reviews the literature that describes the micro level economic and social consequences of homeownership we adopt an interdisciplinary approach and include studies from economics sociology geography political science psychology and other disciplines our focus is on the set of consequences of homeownership in developed countries our list of potential outcomes of homeownership includes the impact on household wealth and portfolio choice mobility labor force participation urban structure and segregation home maintenance political and social activities health demographics self esteem and child outcomes there is substantial evidence that homeownership has important effects on some household behaviors and outcomes however we find that much of the past 30 year s literature on consequences of homeowning is deficient from a theoretical or econometric perspective we suggest solutions and identify research gaps present in the literature

decentralized intraday generation scheduling for multiarea power systems via dynamic multiplier based lagrangian relaxation due to day ahead forecast error in load demand and renewable generation there exists inevitable deviation between real time operation and day ahead generation schedules this paper introduces a decentralized multiarea intraday generation scheduling based on nonlinear ac power flow this approach allows for a more reliable and economic operation with the ability to accurately constrain power and voltage securities at a multiarea scale a dynamic multiplier based algorithm is employed for solving the nonlinear multiarea intraday dispatch model which is fully decentralized and thus preserves autonomy for each area the dynamic multiplier based algorithm presents the advantage of accelerated computation compared to conventional static multiplier numerical simulations illustrate the computational performance and practical value of the proposed multiarea intraday generation scheduling framework and dynamic multiplier based algorithm

probabilistic lmp forecasting considering load uncertainty in power market studies the forecast of locational marginal price lmp relies on the load forecasting results from the viewpoint of planning it is well known that short term load forecasting results always carry certain degree of errors mainly due to the random nature of the load at the same time lmp step changes occur at critical load levels clls therefore it is interesting to investigate the impact of load forecasting uncertainty on lmp with the assumption of a certain probability distribution of the actual load this paper proposes the concept of probabilistic lmp and formulates the probability mass function of this random variable the expected value of probabilistic lmp is then derived as well as the lower and upper bound of its sensitivity in addition two useful curves alignment probability of deterministic lmp versus forecasted load and expected value of probabilistic lmp versus forecasted load are presented the first curve is designed to identify the probability that the forecasted price in a deterministic lmp matches the actual price at the forecasted load level the second curve is demonstrated to be smooth and therefore eliminates the step changes in deterministic lmp forecasting this helps planners avoid the possible sharp changes during decision making process the proposed concept and method are illustrated with a modified pjm five bus system and the ieee 118 bus system

data perturbation based sensitivity analysis of real time look ahead economic dispatch in this paper the sensitivity of look ahead economic dispatch in real time power markets with respect to data perturbation is studied in the look ahead dispatch optimization problem a small change in the data that are used for setting the interspatial and temporal equality inequality constraints and the objective function may negatively affect normal operations such as the calculation of real time wholesale electricity prices and operating costs this could lead to more distorted prices and larger operating costs with the look ahead dispatch than with a static dispatch that use data for a single future time we perturb karush kuhn tucker conditions of the look ahead dispatch optimization formulation and then using them derive a linear sensitivity matrix that assesses the impact of data corruption on look ahead dispatch this matrix illustrates the changing optimal solution of look ahead dispatch subject to potential corruption in various types of spatial and temporal data generator s bidding cost coefficients capacity limits for generators and transmission lines ramp rates and the estimate of initial generation output with ramp constraints and multiple time series of the forecast load for the look ahead horizon the results of the simulation are illustrated with numerical examples in the ieee 14 bus system

convergence of volatile power markets with price based demand response price based demand response dr program is a mechanism for encouraging electricity consumers to dynamically manage their energy consumptions in response to time varying electricity prices and thereby reduce peak electricity demands and alleviate the pressure to power systems however it brings additional dynamics and new challenges to the real time supply and demand balance specifically if real time price based dr programs are widely deployed in the future price sensitive dr load levels would constantly change in response to dynamic real time prices which will impact the economic dispatch ed schedule and in turn affect electricity market clearing prices this paper adopts two methods for examining the impacts of different dr price elasticity characteristics and dr participation levels on the convergence of volatile power market a closed loop iterative simulation method and a non iterative method based on the contraction mapping theorem in this paper convergence refers to the fact that load and or price values will finally converge to a fixed point after a finite number of iterations between the ed problem and the price sensitive dr load adjustment five price sensitive dr performance function categories are used to simulate different nonlinear price elasticity characteristics of dr loads numerical studies illustrate how the convergence status of power markets will be affected by the nonlinear price elasticity dr curves the dr penetration levels and the capacity limits of generating units

a probability model for the electricity price duration curve under an oligopoly market in this paper we propose a new formulation for the price duration curve pdc using probability considerations and provide a procedure for constructing it this curve is expected to be useful in the long term prediction of market prices and is similar in spirit to the load duration curve it shows the proportion of time over a given time horizon during which the real time market price of electricity is expected to exceed specified dollar amounts the price over a long term is a stochastic quantity that depends on physical factors such as production cost load generation availability unit commitment and transmission constraints it also depends on economic factors such as strategic bidding and load elasticity we illustrate a procedure for constructing a stochastic system based model for the pdc taking into account the randomness associated with load and generator outages the effects of unit commitment transmission congestion and transmission outages are not considered we use two economic models one is due to bertrand and represents perfect competition the other model is due to rudkevich et al who have given a closed form expression for the market clearing price in an oligopoly consisting of several identical firms

using a system model to decompose the effects of influential factors on locational marginal prices locational marginal prices lmps are influenced by various factors such as load uncertainty thermal limit capacity reserve and market power we build a system model to quantitatively analyze the effects of these individual factors and their interactions on the mean and standard deviation of the lmps assuming that the factors are either active or inactive according to the sensitivity analysis results from convex quadratic programming lmps are piecewise linear functions of demand variation which is a key property used in the computation this paper attempts to answer the following types of questions 1 to what extent does market power raise the lmps above the marginal cost 2 what effects will generation or transmission capacity expansion have on relieving high lmps under high demand scenarios an ieee 30 bus test system is used as an example to demonstrate our approach

security constrained unit commitment for simultaneous clearing of energy and ancillary services markets this paper introduces a security constrained unit commitment scuc model with emphases on the simultaneous optimization of energy and ancillary services markets benders decomposition is used to decouple the scuc into a unit commitment uc master problem and hourly network security checking subproblems lagrangian relaxation is used to decouple the uc problem into individual single unit commitment problems dynamic programming is used to find the optimal commitment decision a simultaneous marginal curve algorithm is proposed to find the optimal values of energy and ancillary services a six bus system with three units and the ieee 118 bus system with 54 units are analyzed to illustrate the proposed model

electricity market clearing with improved scheduling of stochastic production abstract in this paper we consider an electricity market that consists of a day ahead and a balancing settlement and includes a number of stochastic producers we first introduce two reference procedures for scheduling and pricing energy in the day ahead market on the one hand a conventional network constrained auction purely based on the least cost merit order where stochastic generation enters with its expected production and a low marginal cost on the other a counterfactual auction that also accounts for the projected balancing costs using stochastic programming although the stochastic clearing procedure attains higher market efficiency in expectation than the conventional day ahead auction it suffers from fundamental drawbacks with a view to its practical implementation in particular it requires flexible producers those that make up for the lack or surplus of stochastic generation to accept losses in some scenarios using a bilevel programming framework we then show that the conventional auction if combined with a suitable day ahead dispatch of stochastic producers generally different from their expected production can substantially increase market efficiency and emulate the advantageous features of the stochastic optimization ideal while avoiding its major pitfalls a two node power system serves as both an illustrative example and a proof of concept finally a more realistic case study highlights the main advantages of a smart day ahead dispatch of stochastic producers

optimal joint dynamic pricing advertising and inventory control model for perishable items with psychic stock effect abstract in this study a joint pricing advertising and inventory control problem will be investigated for a firm selling perishable products with psychic stock effect the proposed problem is analyzed in the deterministic multi period setting in which demand at each period depends on not only the amount of inventory displayed and advertising goodwill affected by the firm s current and past advertising efforts but also selling price and freshness index the objective is to determine the optimal pricing advertising and psychic stock strategies maximizing the discount total profit over the infinite planning horizon our theoretical results prove that the firm would adopt a static pricing strategy and then demonstrate that the optimal paths of the advertising goodwill and psychic stock can be determined uniquely we also show that the convergence of the advertising goodwill towards its equilibrium is from above or below depending on the relative location of the initial stock of advertising goodwill with respect to the unique equilibrium stock of advertising goodwill moreover a set of structural properties is developed to explore the relationships among the optimal decisions finally the concluding remarks and suggestions will be provided for future studies