Growing RBFNN-based soft computing approach for congestion management

In the emerging restructured power system, the congestion management (CM) has become extremely important in order to ensure the security and reliability of the system. In addition to this, lack of CM can impose a hindrance in electricity trading. This paper presents a novel, growing radial basis function neural network (GRBFNN)-based approach for CM. For achieving CM, Nodal congestion price (NCP) forecasting is performed in real time competitive power market. NCP forecasting is an effective way of price-based preventive CM as it directly indicates the presence as well as the severity of the congestion in the system. In present paper, GRBFNN has been developed for NCP forecasting dividing the whole power system into various congestion zones. An unsupervised learning vector quantization (VQ) clustering algorithm is applied as feature selection technique for the developed GRBFNN and for partitioning the power system into different congestion zones. For each congestion zone a separate neural network has been developed to ensure faster training and accurate forecasting results. The proposed approach of CM is implemented on an RTS 24-bus system. The results obtained are compared with a different constructive algorithm-based RBF network called as general regression neural network (GRNN) and two back-propagation algorithms based ANNs. Comparison results show that proposed GRBFNN is more computationally efficient with better predictive ability.     

A novel symbiotic organisms search algorithm for congestion management in deregulated environment

Abstract

In today’s competitive electricity market, managing transmission congestion in deregulated power system has created challenges for independent system operators to operate the transmission lines reliably within the limits. This paper proposes a new meta-heuristic algorithm, called as symbiotic organisms search (SOS) algorithm, for congestion management (CM) problem in pool based electricity market by real power rescheduling of generators. Inspired by interactions among organisms in ecosystem, SOS algorithm is a recent population based algorithm which does not require any algorithm specific control parameters unlike other algorithms. Various security constraints such as load bus voltage and line loading are taken into account while dealing with the CM problem. In this paper, the proposed SOS algorithm is applied on modified IEEE 30- and 57-bus test power system for the solution of CM problem. The results, thus, obtained are compared to those reported in the recent state-of-the-art literature. The efficacy of the proposed SOS algorithm for obtaining the higher quality solution is also established.     

Congestion management in dynamic security constrained open power markets

The greatest challenge facing deregulated and unbundled electricity supply industry is the operation of the grid in a non-discriminatory and equitable manner. Transmission pricing and congestion management have been at the center of the debate over facilitating greater competition of electric power generation. This paper studies dynamic security constrained congestion management in an unbundled electric power system. It is possible to reschedule the real power generation along with curtailment of real power loads/transactions to make the system dynamically secure after a fault. A conceptually reasonable and computationally feasible approach for the solution of this problem has been developed for a system with a mix of pool and contract dispatches.     

Market power and welfare effects in DC power flow electricity models with thermal line losses

A nodal electric power network with Cournot–Nash interaction among power generators is formulated as a mixed complementarity problem. The model incorporates a direct current (DC) power flow approximation with thermal line losses to model real-time flows. We include constant wheeling rate and variable congestion charges for transmission of electricity. Market power and welfare effects are measured in an aggregated Indiana electric grid model. We find that imposing DC power flow constraints in a model results in significant changes in social welfare estimates. Line losses are also an important factor affecting market power and welfare of market participants in the case study.     

Market Incompleteness in Regional Electricity Transmission. Part I: The Forward Market

The paper analyses various proposals for the organization of regional electricity transmission in terms of the market incompleteness that they may implicitly assume. Elementary notions of variational inequalities constitute the analytical tool used throughout the paper. The discussion is conducted with reference to the flowgate debate in the US and European proposals for the organization of cross border electricity trade. This first part of the paper discusses market incompleteness in the forward (day ahead) market. The main results can be summarized as follows. An energy market without a market for transmission services is incomplete and hence inefficient. The nodal and flowgate models complete the market when one does not consider contingencies. One can define a notion of transmission capacity (called an extended flowgate) by aggregating line capacities using spot prices. This transmission capacity completes the market and reduces the number of necessary flowgates (possibly to one). But these extended flowgates have variable capacities. As in the case of the nodal model, extended flowgates can accommodate contingencies in the forward market.     

优化进化神经网络的空气质量预测研究

进化神经网络模型与问题内部机制无关,避免了神经网络收敛到局部,但模型存在参数多而过于复杂的问题。对影响基本进化神经网络模型性能的个体编码方式和适应度函数进行优化,并自适应性定义种群交叉率、变异率。以大气中主要污染物SO2为例,考虑气温、相对湿度、风速等影响因子,实验仿真结果表明优化后的进化神经网络较传统的基本进化神经网络模型进化过程收敛更快,预测效果更佳,为环境保护部门提供可靠的决策依据。     

Solution to profit based unit commitment problem using particle swarm optimization

In this paper, an algorithm to solve the profit based unit commitment problem (PBUCP) under deregulated environment has been proposed using Particle Swarm Optimization (PSO) intelligent technique to maximize the GENCOs profit. Deregulation in power sector increases the efficiency of electricity production and distribution, offer lower prices, higher quality, a secure and a more reliable product. The proposed algorithm has been developed from the view point of a generation company wishing to maximize its profit in the deregulated power and reserve markets. UC schedule depends on the market price in the deregulated market. In deregulated environment utilities are not required to meet the demand. GENCO can consider a schedule that produce less than the predicted load demand and reserve but creates maximum profit. More number of units are committed when the market price is higher. When more number of generating units are brought online more power is generated and participated in the deregulated market to get maximum profit. This paper presents a new approach of GENCOs profit based unit commitment using PSO technique in a day ahead competitive electricity markets. The profit based unit commitment problem is solved using various PSO techniques such as Chaotic PSO (CPSO), New PSO (NPSO) and Dispersed PSO (DPSO) and the results are compared. Generation, spinning reserve, non-spinning reserve, and system constraints are considered in proposed formulation. The proposed approach has been tested on IEEE-30 bus system with 6 generating units as an individual GENCO. The results obtained are quite encouraging and useful in deregulated market. The algorithm and simulation are carried out using Matlab software.     

NODAL-BASED ANT COLONY OPTIMIZATION FOR PROFIT MAXIMIZATION OF GENCOS IN A DISTRIBUTED CLUSTER MODEL

In the deregulated electricity market, each generating company has to maximize its own profit by committing to a suitable generation schedule termed profit-based unit commitment (PBUC). This article proposes a nodal ant colony optimization (NACO) solution to the PBUC problem. This method has better convergence characteristics in obtaining an optimum solution. The proposed approach uses a cluster of computers performing parallel operations in a distributed environment for obtaining the PBUC solution. The time complexity and the solution quality, with respect to the number of processors in the cluster, are thoroughly tested. The method has been applied to systems of up to 120 units, and the results show that the proposed NACO in a distributed cluster consistently outperforms the other methods that are available in the literature.     

Electricity price classification using extreme learning machines

Forecasting electricity prices has been a widely investigated research issue in the deregulated power market scenario. High price volatilities, price spikes caused by a number of factors such as weather uncertainty, fluctuating fuel prices, transmission bottlenecks, etc., make the task of accurate price forecasting a formidable challenge for the market participants. A number of models have been proposed by researchers; however, achieving high accuracy is always not possible. In some specific applications such as self-scheduling by demand side participants, certain price thresholds are more useful than accurate price forecasts. In this paper, we have investigated the application of a novel neural network-based technique called extreme learning machine for the problem of classification of future electricity prices with respect to certain price thresholds. Different models corresponding to different lead times are developed and tested with data corresponding to Ontario and PJM markets. It is observed that classification with ELM is fast, less sensitive to user defined parameters and easily implementable.     

Smart consumer load balancing: state of the art and an empirical evaluation in the Spanish electricity market

The basis of an efficient functioning of a power grid is an accurate balancing of the electricity demand of all the consumers at any instant with supply. Nowadays, this task involves only the grid operator and retail electricity providers. One of the facets of the Smart Grid vision is that consumers may have a more active role in the problem of balancing demand with supply. With the deployment of intelligent information and communication technologies in domestic environments, homes are becoming smarter and able to play a more active role in the management of energy. We use the term Smart Consumer Load Balancing to refer to algorithms that are run by energy management systems of homes in order to optimise the electricity consumption, to minimise costs and/or meet supply constraints. In this work, we analyse different approaches to Smart Consumer Load Balancing based on (distributed) artificial intelligence. We also put forward a new model of Smart Consumer Load Balancing, where consumers actively participate in the balancing of demand with supply by forming groups that agree on a joint demand profile to be contracted in the market with the mediation of an aggregator. We specify the business model as well as the optimisation model for load balancing, showing the economic benefits for the consumers in a realistic scenario based on the Spanish electricity market.     

Electric Power Network Oligopoly as a Dynamic Stackelberg Game

Over the last two decades, the electricity industry has shifted from regulation of monopolistic and centralized utilities towards deregulation and promoted competition. With increased competition in electric power markets, system operators are recognizing their pivotal role in ensuring the efficient operation of the electric grid and the maximization of social welfare. In this article, we propose a hypothetical new market of dynamic spatial network equilibrium among consumers, system operators and electricity generators as solution of a dynamic Stackelberg game. In that game, generators form an oligopoly and act as Cournot-Nash competitors who non-cooperatively maximize their own profits. The market monitor attempts to increase social welfare by intelligently employing equilibrium congestion pricing anticipating the actions of generators. The market monitor influences the generators by charging network access fees that influence power flows towards a perfectly competitive scenario. Our approach anticipates uncompetitive behavior and minimizes the impacts upon society. The resulting game is modeled as a Mathematical Program with Equilibrium Constraints (MPEC). We present an illustrative example as well as a stylized 15-node network of the Western European electric grid.     

Distributed control for energy-efficient and fast consensus in wireless sensor networks

The paper proposes a distributed control of nodes transmission radii in energy-harvesting wireless sensor networks for simultaneously coping with energy consumption and consensus responsiveness requirement. The stability of the closed-loop network under the proposed control law is proved. Simulation validations show the effectiveness of the proposed approach in nominal scenario as well as in the presence of uncertain node power requirements and harvesting system supply.     

实时电价下用户侧电力需求响应模型优化策略及数字仿真谈竹奎1,汪元芹2,赵菁2,刘斌1,刘敏2

为解决智能电网发展中用户参与电力市场运营的响应积极性以及用户收益最大化问题,本文在经济学原理基础上,引用需求价格弹性系数表征用户的用电量随电价的变化情况,建立实时电价下的用户负荷调节能力模型,根据该模型,进一步研究了基于实时电价的用户侧电力需求响应模型优化策略,考虑用户在不同响应场景和不同负荷调节潜力下的需求响应。解决供电与用电间的电力供需不平衡问题,实现用户积极响应及其利益最大化,并提高系统稳定性与安全性。以某地需求响应系统为例,对进入现货市场交易的用户进行数字仿真,通过算例分析表明该模型能有效改善用电负荷曲线,减小用户购电成本,验证了基于实时电价下的电力需求响应优化策略的优化效果。     

Price strategies in dynamic duopolistic markets with deregulated electricity supplies using mixed strategies

While effective competition can force service providers to seek economically efficient methods to reduce costs, the deregulated electricity supply industry still allows some generators to exercise market power at particular locations, thereby preventing the deregulated power market to be perfectly competitive. In this paper, we investigate the interdependence of pricing mechanisms and strategy behaviors of the suppliers. A multiperiod dynamic profit-maximizing problem is converted to a bimatrix game that is solved in the framework of mixed strategies. By this procedure, we have at least one Nash solution. Instead of considering only perfectly competitive price and monopoly price, we introduce other prices between these two to simulate the real market better. Numerical examples show that the new entrant that maximizes its profit will not choose the perfectly competitive price even as an entry price.     

基于Agent的电力市场价格仿真研究

电力市场是规模大、层次复杂的系统,电力系统的改革的重点是建立一个竞争机制的电力市场。传统电力系统仿真工具已经难以分析市场中复杂的关系,采用Agent技术仿真已成为复杂系统建模的有效工具。本文对Agent平台上的电力市场价格模拟系统进行研究,模拟电价产生中发电侧、输电侧和用户的竞争,该方法可用来分析多个参与者对电价形成的影响。     

一种基于深度强化学习与概率性能感知的边缘计算环境多工作流卸载方法

移动边缘计算是一种新兴的分布式和泛在计算模式,其将计算密集型和时延敏感型任务转移到附近的边缘服务器,有效缓解了移动终端资源不足的问题,显著减小了用户与计算处理节点之间的通信传输开销.然而,如果多个用户同时提出计算密集型任务请求,特别是流程化的工作流任务请求,边缘计算环境往往难以有效地进行响应,并会造成任务拥塞.另外,受...     

Network Expansion to Mitigate Market Power

Constrained transmission capacity in electricity networks may give generators the possibility to game the market by specifically causing congestion and thereby appropriating excessive rents. Investment in network capacity can ameliorate such behavior by reducing the potential for strategic behavior. However, modeling Nash equilibria between generators, which explicitly account for their impact on the network, is mathematically and computationally challenging. We propose a three-stage model to describe how network investment can reduce market power exertion: a benevolent planner decides on network upgrades for existing lines anticipating the gaming opportunities by strategic generators. These firms, in turn, anticipate their impact on market-clearing prices and grid congestion. In this respect, we provide the first model endogenizing the trade-off between the costs of grid investment and benefits from reduced market power potential in short-run market clearing. In a numerical example using a three-node network, we illustrate three distinct effects: firstly, by reducing market power exertion, network expansion can yield welfare gains beyond pure efficiency increases. Anticipating gaming possibilities when planning network expansion can push welfare close to a first-best competitive benchmark. Secondly, network upgrades entail a relative shift of rents from producers to consumers when congestion rents were excessive. Thirdly, investment may yield suboptimal or even disequilibrium outcomes when strategic behavior of certain market participants is neglected in network planning.     

Multi area AGC scheme using imperialist competition algorithm in restructured power system

This paper is focused on optimization based design methodology and application of PID controller in restructured, competitive electricity market environment, for AGC problem. The paper compares two search algorithms for designing of PID controller used for AGC in multiarea power system. The optimal parameters of PID controller have been determined with the use of Imperialist Competitive Algorithm (ICA). A deregulated scenario has been considered to develop the model of the multiarea AGC scheme. This paper presents that the ICA tuned PID (ICA-PID) controller can optimally regulate the generators output and can provide the best dynamic response of frequency and tie-line power on a load perturbation. The performance of proposed controller has been checked on 2-area thermal power system and 3-area thermal-hydro power system with the consideration of generation rate constraint (GRC). The results obtained by ICA-PID controller and genetic algorithm tuned (GA-PID) controller have been compared on the basis of performance parameters (settling time and oscillations). It is seen that ICA-PID controller shows the better performance as compared to GA-PID controller.     

A Large-Scale Spatial Optimization Model of the European Electricity Market

In this paper, we present a large-scale spatial model of the European electricity market including both generation and the physical transmission network (DC Load Flow approach). The model was developed to analyze various questions on market design, congestion management, and investment decisions, with a focus on Germany and Continental Europe. It is a bottom-up model combining electrical engineering and economics: its objective function is welfare maximization, subject to line flow, energy balance, and generation constraints. The model provides simulations on an hourly basis, taking into account variable demand, wind input, unit commitment, start-up costs, pump storage, and other details. Various forms of spatial price discrimination can be implemented, such as locational marginal pricing (“nodal pricing”), or zonal pricing. With over 2,000 nodes and over 3,000 lines, this is one of the largest models developed to date, and allows a highly differentiated spatial analysis. We report modeling results regarding efficient congestion management for Germany and Europe, optimal network expansion under the aspect of increased wind energy production, and the impact of network constraints on location decisions of generation investments.     

基于Hadoop的输电线路在线监测数据模型及技术研究

输电线路是电力系统中关键的组成部分,输电线路在线监测技术的应用产生了海量线路运行数据,对数据的深入挖掘成为现阶段电力大数据研究的热点。随着智能电网数据应用的深入,为保证电力系统可靠运行提供了新的解决方案。在研究输电线路在线监测数据类型、数据特征、数据需求的基础上,提出了符合智能电网电力大数据结构特征的Hadoop监测数据模型设计,包含了多维度数据信息输入、分布式数据存储、分布式数据处理的三个层次。通过搭建基于Hadoop集群的大数据处理环境,在MapReduce并行运算模式下实现PCA-SVM聚类算法,以输电线路故障类型识别为例,实现了基于数据分析的输电线路故障辨识,验证该模型实现输电线路在线监测的可行性。