Congestion management with ex ante pricing for decentralized electricity markets

In this paper, the authors present a method and a model for managing transmission congestion based on ex ante congestion prices. Their method is influenced by the yield management approach widely used for airline reservation systems, and their model is built based on the relations between transmission congestion prices and electricity commodity prices that exist for an optimal solution. They formulate the congestion pricing problem as a master problem and the electricity commodity (energy and reserve) pricing as subproblems. Examples are presented to illustrate how a system operator can use this approach to compute ex ante congestion prices and how market operators can determine clearing prices and schedules of forward electric energy and reserve markets.     

Transmission access issues

This paper is based on the material presented at the IEEE 1994 Winter Power Meeting Panel on Transmission Access issues, sponsored by IEEE task force on transmission access. The paper contains short notes by four panelists on transmission access: (1) institutional issues; (2) planning and operation issues; (3) analytical issues; and (4) economic issues     

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.     

解除管制的电力零售市场实时电价研究

零售侧打破垄断引入竞争是电力市场发展的趋势,制定合理的零售电价是市场开放的关键.根据电力零售市场的特点,基于负荷价格响应的定义以及边际成本定价理论,推导出了考虑负荷价格响应的有功实时电价的表达式.以社会成本最大化为目标函数,建立了考虑负荷价格响应特性的最优潮流模型,从而求解出未来引入竞争的电力零售市场中电力库交易模式下的实时电价.采用32节点配电系统对所提方法进行仿真,结果证明为促进零售市场竞争、引导用户合理用电提供了合理有效的定价方法.     

综合考虑成本组成及其分摊的输电定价新方法

提出了一种新的输电定价方法,将输电费用成本组成分成固定成本、变动成本和附加成本。根据交易种类的不同对固定成本进行修正后再收费;采用边际网损系数法计算用户分摊的变动成本;利用边际成本法计算附加成本,判断交易量的边际变化是否超过设备的最大容量对用户进行收费。均给出了成本分摊的计算公式,该方法避免了用户间的交叉补贴现象,算法清晰,体现了输电定价原则,能引导输电服务更合理地收费,保证电网公司成本回收并能获得一定的利润。     

基于SRMC的区域电力市场输电定价方案

从我国区域电力市场的运行实际出发,提出一种基于SRMC的输电定价方案,该方案不仅可以向发电厂和用户提供有效的经济信号,引导短期市场效率,而且可以保证电网公司的年收支平衡,并为电网扩建积累专项资金,具有一定的合理性和实用性.     

国外输电定价理论方法及对我国的启示

输电定价是电力市场有效运行的关键,正确的输电定价首先要保证资源的有效分配。讨论输电电价的基本原则,把各种输电定价方法归为2类:成本定价法和市场定价法,并对其实用性进行讨论。从社会福利最大化的角度分析,输电效率定价模式会导致输电公司固定投资难以回收。因此,对于处于垄断地位的电网公司,其输电定价应以成本为基础,同时必须接受管制;市场化的定价方式仅限于线路阻塞时容量的分配。     

Transmission loss unbundling and allocation under pool electricity markets

This paper presents a methodology based on the circuit theories for unbundling and allocation of transmission losses among the participants of a pool-based electricity market. Starting from a known operation point and using the basic network equations without additional assumptions, an expression of the branch losses based on nodal current injections is derived. Since the power flow equations and circuit theories are satisfied, the methodology turns explicit, in a natural way, separating the losses at each system branch and assigning the responsibility to the respective market participants. It means that the loss allocation of each branch, which is produced by each generator and consumer, is obtained. Extensions and strategies considering unsubsidized and predefined proportion-based loss allocation as well as issues related with the allocation fairness and transparency are also included. Comparisons with previous methods and validation tests of the proposed method are reported by using the IEEE Reliability Test System.     

Power flow tracing based transmission congestion pricing in deregulated power markets

The objective of this paper is to propose a simple transmission congestion pricing scheme based on tracing principle by considering generator fixed cost, cost for incurring loss and transmission congestion cost. Restructuring has brought about considerable changes by the virtue of which electricity is now a commodity and has converted into deregulated type. Such a competitive market has paved way for innumerable participants. This concept of restructuring has led to overloading of transmission lines. In this paper, power flow tracing has been employed by using suitable optimization algorithm, where the real power generation has been maximized. Congestion in the transmission line has been produced in a new fashion by maximizing the real power demand. The power flow under normal operating condition and congestion is determined and hence the difference in power flow is estimated. Based on the estimated power flow difference, the transmission line congestion cost is computed. Pool model and bilateral model has been considered in simulation study to introduce the concept of deregulation. The proposed method is tested and validated on Modified IEEE 30 bus test system and Indian utility 69 bus test system.     

Closure on "Equilibrium of auction markets with unit commitment: the need for augmented pricing"

The authors reply to the comments by M. Madrigal (see ibid., vol.18, no.2, p.961, 2003) on their original paper (see ibid., vol.17, p.798-805, 2002), answering the two questions he raised.     

A method for pricing VAR providers in the electricity markets considering voltage security

This paper presents a novel approach for procuring VAR service in a competitive market‐based environment, in which the transmission operator (TO) is supposed to run the market and enter into long‐term contracts with the successful candidates for providing the required VAR whenever called upon. The proposed method is new in that the VAR procurement problem and control problem, including load shedding, are uniformly formulated so that N‐1 security is guaranteed. Voltage stability is newly introduced into the VAR market problem in an explicit manner for normal and emergency states. The objective function is the total cost for TO, which includes the payment to VAR providers, power loss cost for normal states, and control costs for emergency states. The explicit inclusion of voltage security margin enables the TO to easily identify the critical VAR providers who should be contracted to maintain the required security level. This implies that the VAR providers in this market will be fairly remunerated on the basis of their contributions to the system security that measures the relative worth of each VAR provider. The proposed method has been applied to the IEEE 57 bus‐system to demonstrate its usefulness. © 2006 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

Transmission congestion and voltage profile management coordination in competitive electricity markets

This paper describes a generalized active/reactive iterative coordination process between GENCOs and the Independent System Operator (ISO) for active (transmission congestion) and reactive (voltage profile) management in the day-ahead market. GENCOs apply priced-based unit commitment without transmission and voltage security constraints, schedule their units and submit their initial bids to the ISO. The ISO executes congestion and voltage profile management for eliminating transmission and voltage profile violations. If violations are not eliminated, the ISO minimizes the transmission and voltage profile violations and sends a signal via the Internet to GENCOs. GENCOs reschedule their units taking into account the ISO signals and submit modified bids to the ISO. The voltage problem is addressed and a linear model is formulated and used in the proposed method. The voltage problem is formulated as a linear programming with a block-angular structure and Dantzig-Wolfe decomposition is applied to generate several smaller problems for a faster and easier solution of large-scale power systems. Two 36 unit GENCOs are used to demonstrate the performance of the proposed generalized active/reactive coordination algorithm.     

英国输电定价模式及在我国电网中的应用

英国是最早实行电力市场化改革的国家之一，于2001年实行了电力市场新模式，其中输电费用的计算比较完善。从接网费用、电网使用费及平衡服务费用3个方面阐述英国的输电定价机制。应用其电网使用费的模型对我国某大区电网进行电网使用费的计算与分析，结果表明该方法不但可给发电厂商和用户提供有效的经济信号，而且还可保证电网公司的年收支平衡，值得借鉴。     

Transmission loss allocation. II. Multiple interconnected energy markets

For pt.I see ibid., vol.18, no.4, p.1389-94 (2003). This paper presents a new methodology based on the incremental transmission loss concept for allocating electric losses to generators and loads, participating in multiple interconnected energy markets. The main objective is to generalize the formulation proposed in the companion paper, Part I, in order to identify through a decomposition technique, the amount of losses that each participant in the market causes on all system areas. The concept of interchange losses is introduced: the total amount of losses that occurs outside a given market whose agents are responsible for causing them. Some criteria to share these losses among the market agents are presented and discussed. The IEEE Reliability Test System is used to illustrate the proposed methodology.     

多接入点分布式光伏发电系统与配电网交互影响研究

针对分布式光伏发电的谐波源特性和功率波动性,对分布式光伏接入对配电网谐波、电压波动和闪变的影响进行了分析,并分析了背景电能质量问题对光伏并网点电能质量的影响。同时在DIg SILENT/Power Factory仿真平台上搭建了国际大电网会议(CIGRE)认为适合进行分布式发电接入配电网特性研究的典型配电网络结构,并根据IEC 61400-4-15标准在该平台上搭建了IEC电压闪变仪,对含多接入点分布式光伏发电的配电网的谐波传输和放大特性、电压波动和闪变的影响和评估进行了仿真分析。仿真结果表明,含多接入点分布式光伏的配电网中谐波传输和放大特性非常复杂;配电网各母线节点的电压波动和闪变值的大小与该母线节点的短路容量和功率波动密切相关。     

Distribution access pricing: application of the OFTEL rule to a yardstick competition scheme

The paper formulates an access-pricing model applied to electricity distribution, based on the UK Office of Telecommunications (OFTEL) model, originally structured to price telecommunications monopolistic-essential facilities. The aim is to achieve an optimal access price charge, in an environment where a distribution network monopoly serves both regulated and nonregulated customers. The nonregulated market faces competition, so that the competitors must use the network to reach their customers. A usage-based hybrid model is proposed to couple with a tariff scheme for regulated customers that uses yardstick competition. A way to set appropriated opportunity costs by the use of the OFTEL model is introduced. Finally, the paper focuses on properly recognizing both regulated distribution and competitive supply costs. The scheme is assessed within the Chilean regulatory scheme, proposing a way to establish marginal and fixed distribution costs for distribution companies.     

Transmission loss compensation in multiple transaction networks

We develop and apply the equivalent loss compensation concept to construct flexible and effective procedures for compensating losses in a multi-transaction network. The procedures are developed in the multiple transaction framework and are based on the physical-flow allocation of losses among the transactions. The proposed procedures provide transactions the choice of selecting self-acquisition of loss compensation at designated bus(es) or to purchase the loss compensation service from a central independent grid operator (IGO). The IGO can provide loss compensation as a value-added service to its transmission customers, IGO-acquisition of loss compensation uses a linear program formulation in which network constraints are explicitly represented to determine the solution which gives the least-price at which the IGO can acquire the service. The self-acquisition service may co-exist side-by-side with the IGO-acquisition and any physically feasible combination of these acquisition schemes is possible. The effectiveness and flexibility of the procedures are illustrated with numerical results using the IEEE 118- and 300-bus systems     

Transmission congestion management in bilateral markets: An interruptible load auction solution

This paper demonstrates that appropriate invocation of interruptible loads by the independent system operator (ISO) can aid in relieving transmission congestion in power systems. An auction model is proposed, for an ISO operating in a bilateral contract dominated market, for real-time selection of interruptible load offers while satisfying the congestion management objective. The proposed congestion management scheme using interruptible loads can specifically identify load buses where corrective measures are needed for relieving congestion on a particular transmission corridor. The N − 1 contingency criterion has been taken into account to simulate various cases, and hence, examine the effectiveness of the proposed method. It has been shown that the method can assist the ISO to remove the overload from lines in both normal and contingency conditions in an optimal manner.     

Transmission pricing of distributed multilateral energy transactions to ensure system security and guide economic dispatch

In this paper, the authors provide a simulations-based demonstration of a hybrid electricity market that combines the distributed competitive advantages of decentralized markets with the system security guarantees of centralized markets. In this market, the transmission service provider (TSP) guides an electricity market toward the optimal power flow (OPF) solution, even when maximizing its own revenue. End users negotiate with each other to determine an energy price and then submit separate bids for transmission to the TSP. The TSP returns with prices for transmission, allowing end users to respond. In simulations, this hybrid-decentralized market approaches the near-optimal results of fully coordinated and constrained markets. Additionally, this market exhibits properties that remove incentives for the TSP to withhold capacity. This hybrid market leads a market toward the optimum while allowing the TSP and the end users to act out of self-interest.     

考虑多市场主体参与的气电区域综合能源系统市场定价策略

随着多市场主体接入,如何管理系统中的分布式资源成为气电区域综合能源系统的核心问题。从激励价格角度出发,建立含商业楼宇和分布式电源2类市场主体的区域综合能源系统日前市场出清模型,综合考虑节点净有功负荷、净无功负荷和天然气负荷对系统运行的影响,通过引入多类灵敏度因子线性化潮流约束和稳态气流约束;进一步地,将出清的节点边际价格分为有功基础电价、无功基础电价、阻塞管理电价、电压支撑电价、网损边际电价、基础气价和气压支撑价格7类,通过不同价格信号引导促使市场主体调节自身运行方式支撑系统运行。基于改进的IEEE 33节点配电网和24节点气网构成的区域综合能源系统的仿真结果验证了所提出的基于节点边际价格分解的定价策略的有效性和合理性。