Modified penalty function method for optimal social welfare of electric power supply chain with transmission constraints

Many power system application problems utilize optimal social welfare model as a decision-making tool. In this paper, we tackle the optimal social welfare problem based on a mathematic modeling framework capable to capture the interactions among decision-makers in an electric power supply chain network with consideration of transmission power flows and constraints which are neglected in previous literature, and present a generalized electric power supply chain network equilibrium model. In this model, each player tries to maximize its own profit and competes with others in a noncooperative manner. The Nash equilibrium conditions of these players form a finite-dimensional variational inequality problem (VIP). A modified penalty function (MPF) method is then used to replace conventional extragradient method for solving VIP by transforming VIP into a nonlinear programming problem. Numerical tests are conducted to demonstrate the effectiveness of the MPF for solving the VIP-based social welfare maximization model in the context of an electric power supply chain network.     

Reliability analysis of electric supply including standbygenerators and an uninterruptible power supply system

This paper presents a methodology for the reliability analysis of standby and emergency power systems. The techniques are illustrated using an example of standby generators and an uninterruptible power supply system     

集成定价法在输电电价中的应用

对输电电价的定价方法进行了研究,对输电网的成本进行了分析,将其成本分为固定成本和变动成本2大类,固定成本基本上不随时间变化,变动成本随时间变化而不断改变。提出了集成定价思想,即对输电网的固定成本采用综合成本定价法,按最大需量进行分摊,而对变动成本则采用基于边际成本定价法的实时电价并进行实时分摊,两者有效结合即得出输电网的电价模型。该模型可称为集成定价法下的节点电价模型,可以应用于实时电价、分时电价、日前市场电价和远期合同电价。通过算例说明了该电价模型的具体应用。     

A pricing method for transmission loss based on sensitivity analysis

This paper presents a method to evaluate the economic value of transmission loss based on the share proportion principle and the sensitivity analysis. We first formulate an optimal power flow problem to derive the operation conditions, the nodal prices of each bus, and the transmission prices between two buses and then trace the transmission loss during operation based on the share proportion principle of the graph theory. The sensitivity analysis has been used to identify the wheeling path from each generator to any load, and the value of transmission loss is also evaluated. The proposed method is applied to the IEEE 30-bus standard system, which confirms our theoretical results. The proposed method can be used not only to improve the efficient usage of the power grid and congestion management but also to provide valuable economic signals for the generation or transmission investment.     

Linear programming techniques for developing an optimal electrical system including high-voltage direct-current transmission and storage

The planning and design of an electric power system, including high-voltage direct-current transmission, is a complex optimization problem. The optimization must integrate and model the engineering requirements and limitations of the generation, while simultaneously balancing the system electric load at all times. The problem is made more difficult with the introduction of variable generators, such as wind and solar photovoltaics. In the present paper, we introduce two comprehensive linear programming techniques to solve these problems. Linear programming is intentionally chosen to keep the problems tractable in terms of time and computational resources. The first is an optimization that minimizes the deviation from the electric load requirements. The procedure includes variable generators, conventional generators, transmission, and storage, along with their most salient engineering requirements. In addition, the optimization includes some basic electric power system requirements. The second optimization is one that minimizes the overall system costs per annum while taking into consideration all the aspects of the first optimization. We discuss the benefits and disadvantages of the proposed approaches. We show that the cost optimization, although computationally more expensive, is superior in terms of optimizing a real-world electric power system. The present paper shows that linear programming techniques can represent an electrical power system from a high-level without undue complication brought on by moving to mixed integer or nonlinear programming. In addition, the optimizations can be implemented in the future in planning tools.     

Selection of an optimal supply system for a ring-type electric magnet for a U-70 accelerator

Studies on selecting an optimal power-supply system for a ring electric magnet of an U-70 accelerator with the use of semiconductor converters are described. It is shown that, under symmetrical control of converter gates, double activation within a period of 50 Hz does not show any advantage in terms of reactive power supplied form the network compared to operation without double activation. In order to reduce the reactive power at certain load currents without modifying the power part of the converter and supply scheme, it is a good idea to apply a step-by-step control of gate groups in each pair of opposite connected three-phase bridges of the converter. Use of this control method can reduce the reactive power at a stage of load dc maintenance from 36.729 to 3.264 Mvar while simultaneously reducing the full supply power. In addition, 220-kV bus voltage variations caused by operation of the converter are reduced to admissible values. Integration into the power part of the circuit of an additional three-phase supply source with a lower voltage level than for an existing basic source will also allow reduction of supplied reactive power and higher flexibility of control of the converter operation.     

Marginal cost of transmission system adequacy for spot pricing

A model of marginal adequacy costs is developed in order to reflect the influence that any nodal load has on system static security. An adequacy cost function is defined, making use of the load that must be theoretically withdrawn at each node in order to re-establish power flows on transmission elements, after any static contingency of a predefined set occurs. A minimal adequacy transport system is defined as a primary system used as reference for adequacy calculation purposes. Inclusion of adequacy cost function leads to co-ordination equations, which permit identification of marginal costs that are suitable for partial transmission equipment investment recovery. Results of simulations on the reliability test system (RTS) show important costs' components, which are variable in time and space, thus being appropriate for spot pricing schemes. It is verified that a significant part of transmission investment can be recovered by means of the marginal costs of adequacy.     

Considering system non-linearity in transmission pricing

In this paper a new approach for transmission pricing is presented. The contribution of a contract on power flow of a transmission line is used as extent-of-use criterion for transmission pricing. In order to determine the contribution of each contract on power flow of each transmission line, first the contribution of each contract on each voltage angle is determined, which is called voltage angle decomposition. To this end, DC power flow is used to compute a primary solution for voltage angle decomposition. To consider the impacts of system non-linearity on voltage angle decomposition, a method is presented to determine the share of different terms of sine argument in sine value. Then the primary solution is corrected in different iterations of decoupled Newton–Raphson power flow using the presented sharing method. The presented approach is applied to a 4-bus test system and IEEE 30-bus test system and the results are analyzed.     

An alternative method for the reliability differentiated transmission pricing

The reliability of power systems covers all aspects of the ability of the system to satisfy the customer requirements concerning the continuity of supply. The underlying concept is that the transmission reliability margin (TRM) must be secured for the overall system to survive the sudden and unanticipated occurrence of any possible disturbance that may be represented by the mostly common index-forced outage rate. In this regard, this paper explores the probabilistic approach to the calculating of all market participants’ contributions to the TRM by taking into account the forced outage rate of each circuit across the entire network. With these reliability contributions, we can allocate the reliability cost to the users in a more reasonable way. Finally, the proposed method is applied to a 3-bus test system, which is very comprehensive and self-explanatory.     

输电阻塞情况下电能计价的LMP方法

随着电力市场改革的深入,输电阻塞成为电力系统中常见的问题。通过5节点电力系统示例分析了LMP方法用于阻塞情况下电能市场计价和系统结算的过程,并介绍了这种方法的应用情况。     

最优组合预测方法在船舶电推系统中的应用

为了进行船舶电力推进系统的运行状态预测,采用了最优组合预测方法。该方法是在分析单项预测方法的基础上,以预测误差平方和最小为目标进行优化,形成最优组合预测模型。应用最优组合预测方法建立了船舶电力推进系统的预测模型,结合主要运行参数的实测数据进行了预测模型仿真。通过对比实船数据和仿真结果,表明采用最优组合预测方法可有效减小预测误差,具有一定的优越性。     

Markov method for generating capacity reliability evaluation including operating considerations

A new approach is introduced for calculating the generation system reliability indices such as loss of load expectation, frequency of load loss and the mean duration. The Markov approach is used for modelling the generation and load to include the effect of operating considerations such as unit duty cycle, start-up failure probability and start-up delay. A computer program has been developed to implement the Markov approach. This method is compared with recursive techniques and a close agreement between the results is obtained.     

谐波下的电能计量及电能质量分析方法

对谐波下电能计算和电能质量分析的方法进行了讨论,着重对积分电能算法和FFT变换方法进行了对比介绍。     

A new decomposition based method for optimal expansion planning oflarge transmission networks

A new method is presented for long-range transmission network expansion planning, based on the decomposition principle. The overall transmission expansion planning task is divided into two problems, the first one dealing with investments, and the second with operations. The investment problem is specified as the minimum cost problem of network programming, leading to the decomposition into the model of minimum load curtailment and the proposed model of the (local) marginal network. The operation problem is solved by applying the Monte Carlo simulation, with suitable control strategies and additional reliability constraints. The final result is the software package, verified on test examples, as well as on the real transmission network of the power pool of eastern Yugoslavia     

电力机车辅助电机供电系统的研究设计

通过分析电力机车劈相机辅助供电存在的问题,研究设计了一种静止式的交直交变流器,采用一整多逆的电路结构方案,应用于SS3B电力机车为辅助电机供电。变流器输入将原来并联绕制的两个变压器双饼绕组改为串联连接以提高输入电压。将逆变器输出的SPWM波滤波成准正弦波,以满足普通异步电动机的运行要求。按照电力机车辅机的类型和运行工况,给三个逆变器单元分配负载。     

国外输配电定价体系分析及其对构建新型输配电价体系的启示思考

针对我国省级电网现有输配电价中容量电费占比比较低,固定成本难以回收问题,研究新型电力系统建设背景下输配电电价体系问题。梳理了国外比较有代表性的英国、美国、法国等在完全电力市场环境下输配电电价体系,总结其特点和规律。在此基础上,结合构建新型电力系统的发展需求,分析构建以容量电价为基础的输配电价新体系的必要性,并以2021年度某省11个地级市大工业用户的电量数据为例,测算以容量电价为主的输配电价水平。测算结果表明,若实行容量电价,即使大量光伏并网,导致负荷水平下降,输配电成本仍然能够足额回收,对于我国省级电网输配电定价机制的设计具有参考意义。     

输电网的拉姆齐定价研究

由于输电网具有长期规模经济性,基于最优潮流和节点电价(LMP)模型的输电阻塞电价收入不足以弥补输电公司的总成本.采用拉姆齐定价(Ramsey Pricing)模型对满足输电公司预算平衡约束条件下的以电力市场长期效率为优化目标的输电电价进行了研究,结果表明,输电公司主要通过向下扭曲输电容量或降低输电交易量来实现盈亏平衡,而输电的拉姆齐价格的变化与各节点的发电公司的供给价格弹性以及用户的需求价格弹性有密切关系.对一个3节点电网的算例分析结果验证了模型的合理性.     

电力市场价格体系初步探讨

给出了电力市场建立背景、交易模式、定价方法,对电力市场电价的分类及确定方法进行了初步探讨,以适应电力市场建设工作的进程.     

插电式混合动力汽车电驱动系统过压抑制最优控制

在复杂的行驶工况下,插电式混合动力汽车经常处于启停状态,大电流脉冲对汽车电驱动系统高压总线带来巨大冲击,造成高压总线峰值电压不断上升,从而极易造成车辆安全事故。针对插电式混合动力汽车电驱动系统高压总线过压问题,提出一种基于Bang-Bang控制策略来抑制高压总线上的峰值电压,在汽车电驱动系统过压保护装置的实验环境中验证采用的Bang Bang控制策略的准确性,实验结果表明,采用Bang-Bang控制策略能够有效地抑制高压总线过压,保证混合动力汽车的行驶安全。