Luis Gallego

Strategic bidding in Colombian electricity market using a multi-agent learning approach

In this paper, a multi-agent model of an electricity market is proposed using the agent-based computational economics (ACE) methodology. The proposed methodology for modeling the bidding price behavior of Generation Companies (GENCOs) is based on a reinforcement learning algorithm (Q-learning) that uses some soft computing techniques to face the discovery of a complex function among bidding prices, states and profits. The proposed model also comprise the power system operation of a large-scale system by simulating optimal DC power flows (DCOPF) in order to obtain real dispatches of agents and a mapping from action space (bidding strategies) to quantities dispatched. In this model, agents are provided with learning capabilities so that they learn to bid depending on market prices and their risk perception so that profits are maximized. The proposed methodology is applied on colombian power market and some results about bidding strategies dynamics are shown. In addition, a new index defined as rate of market exploitation is introduced in order to characterize the agents bidding behavior.

A methodological proposal for monitoring, analyzing and Estimating Power Quality indices: the case of Bogotá-Colombia

The estimation of power quality (PQ) indices has a vital importance on the development of national PQ standards not only because provides truthful information about PQ conditions in our facilities, but also because permits to establish, with an own criterion, the values for the limits of the most common PQ disturbances. This paper proposes a methodology for the estimation of PQ indices based on statistical sampling and weighting factors techniques which are applied for commercial and industrial customers in the city of Bogota. In addition, some strategies for the classification of the type of customer as well as some final obtained values of PQ indices in Bogota are presented.

Impact Assessment of Power Quality Limits in Colombia: a Regulatory Approach

In order to improve present regulations about power quality (PQ) in Colombia, an impact assessment of PQ limits among utility companies and customers is presented in this paper. This evaluation takes into account results obtained from a previous project of PQ measurements in Bogota-Colombia (PQB) over a representative sample of end users. This paper evaluates the percentage of users that would be surpassing some proposed limits for PQ disturbances such as: THD, TDD, individual harmonics, unbalance voltage, flicker and unbalance current. This analysis was carried out for industrial and commercial facilities taking into account that these users require higher levels of power quality and therefore may inquire in bigger costs in case of poor power quality conditions compared to other type of users such as residential customers. The results achieved in this work show that for some disturbances is possible to apply a regulation based on international standards as IEC and IEEE but in other parameters their application could become very expensive for utilities and end users

Web based management system for power quality assessment and detection of critical zones

The implementation of a web system information management for assessment of power quality indices and detection of critical zones on a distribution system is proposed in this paper. The proposed system was implemented on a APACHE server platform, consisting of three main parts. The first part registers, pre-processes and stores power quality measurements on an open source data base using MySQL. In the second part power quality indices are calculated for each substation, such indices allow the evaluation of disturbances like voltage sags, voltage swells, voltage flicker (Pst) and voltage unbalance. Finally, in the third part the indices are displayed as power quality maps by means (Google Maps) tools, where critical zones are identified for each disturbance according to disturbance activity and severity criteria. This is a low cost, useful and easy to implement tool by the network operator, also can be implemented by the regulatory body for end user consultations.

A new methodology for the comparative analysis of sags among substations in a distribution network in Colombia

In this paper, a new methodology to achieve comparative analysis of sags among substations in large distribution networks is proposed. The proposed methodology consists in three stages as follows. First, data acquired from a Power quality measurement system is considered. Second, sags disturbances are classified and quantified according to a proposed level of severity. Third, an index called Sags Activity index-SAI is proposed allowing to weight and rank the severity of sags among the affected substations. The results show that this index might be easily used by both, the electric companies and the regulator entities to establish limits for sags disturbances.

Agent learning methodology for generators in an electricity market

In this paper, a model of the Colombian electricity market is implemented using the agent-based computational economics (ACE) methodology. The paper propose a methodology to model the offer price behavior of generation companies upon the actual colombian market structure and the effects in market prices and agentspsila profits. This model is based on a learning algorithm that uses some soft computing techniques to face the discovery of a complex function among offer prices, power system variables and profits. In addition, this methodology allows the agents to improve their offer strategies by maximizing their own profits. Finally, the paper presents some results obtained from the model about the behavior of spot prices and agents profits.

Modeling of bidding prices using soft computing techniques

In this paper an strategy for discovering patterns over the continuous domain of bidding prices is proposed. In particular, the proposed method represents bidding functions as points in a multidimensional space where a clustering algorithm is applied. On the other hand, as a result of this method, a dramatic reduction over the search space of bidding strategies is achieved. In addition, some relations of dominance over bidding strategies are found, improving the pattern recognition process of agentpsilas bidding behavior. This method is applied on the bidding prices database for some GENCOpsilas of the colombian power market. Furthermore, an application of some data mining algorithms is presented with the purpose of quantifying some hypothesis formulated on the effect of hydrology over spot and bidding prices.

Implementation of Genetic Algorithms in ATP for Optimal Allocation and Sizing of Active Power Line Conditioners

In last years optimal allocation of active power line conditioner (APLC) at industrial facilities has become an important research subject. In this work the genetic algorithms (GA) are used to determine the allocation and sizing of APLCs. This methodology is implemented in ATP (alternative transients program), and particularly with its components called ATP models routines. The main topic of the paper is to illustrate the process used to achieve the implementation of GA with these components using ATP foreign functions. The structure of chromosome, the genetic operators and a novel concept of ATP models networks are described. The approach proposed is applied on an 11 bus test system, illustrating the minimization of voltage distortion at PCC (point coupling common) and the current harmonic injection of APLCs

Fault zones location on distribution systems based on clustering of voltage sags patterns

A new methodology for estimation of voltage sags patterns and clustering of fault zones in high and medium voltage electric is presented. The proposed methodology comprises three stages. First, network modelling and faults simulation were performed in order to get information about voltage sags caused by faults in the transmission system. Voltage sags patterns were identified at the second stage by means of a k-means clustering algorithm, allowing the determination of fault zones. Using the power quality measurements data base of the major electricity utility of Bogotá, voltage sags were classified according to the previously determined voltage sags patterns. At the third stage of the methodology a comparison between simulated and measured sags is performed, allowing the identification of sags caused by faults.

Evaluation and identification of critical zones due to sag activity

This paper proposes a methodology to identify critical zones in electric distribution systems due to sag activity. The methodology is based on the acquisition of Power Quality (PQ) information in substation buses, measurements that are obtained through a PQ analysis system demanded by the Colombian regulator CREG1 to all electric distribution companies of the country. The methodology is developed in three stages. The first stage consists in a preprocessing of sag events data and its proper organization in a PQ database. Next, the sag activity assessment in each substation bus is achieved as a function of both, the number of times that each substation bus was the cause of a sag event and the number of substation buses affected by that particular sag event. Finally, a geographical identification by means of sag maps where the electric companies may focus their efforts to improve PQ. This methodology was applied to the whole electric distribution system in Bogota-Colombia, showing some interesting results.