Optimal bidding models of power plants considering transmission congestion

In order to achieve optimal bidding strategy of power plants in electricity market, the authors build optimal bidding model by predicting the bidding coefficients of competitors, and the optimal bidding coefficient without considering transmission capacity is achieved. Based on the bidding coefficients, the market clearing model is built, and the expected market clearing price is achieved. According to the expected values, the authors calculate the power flow. When forecasting the transmission congestion, this paper presents an optimal bidding model taking transmission congestion into account. Based on sensitivity analysis, the output regulation of power plants with minimum cost of eliminating congestion is achieved. Simulation results demonstrate that the proposed method can help power plants achieve the optimal profit.     

Prediction Method of Electrical System Marginal Price Based on Sequence Operation Theory

The price of electricity is one of the key questions in the electricity market. As the widely used theory of marginal price of electricity in the power system, its marginal price of electricity predicts that should fully consider the uncertainty of load, uncertainty of generating set forcing stoppage and uncertainty of the quotation to power generator at random. Through redefining effective capacity state and derivation polymorphism sets, the systematic effective capacity function of prohahility is found out by applying probability sequence operation theory to generate electricity, a kind of other method of the systematic effective capacity function of probability has been found. Based on this function of probability distribution and the definition of system marginal price, the authors fully consider various uncertainty factor of effecting system marginal price, accurate forecast system marginal price. Numerical example analysis have proved the correctness of theoretical analysis, show the precision of algorithm forecast get raising.     

Comparatively Research of Methods of Electricity Pricing at Transitional Period in China

With the reform toward power market processing, how to decide electricity price becomes a key problem which one power plant have to face. So in this paper, the authors show two ways to the problem, a pricing model by account and a pricing model by economics, then they analyze the cost structure and counting principle of three-electricity price, which is determined by the methods of repayment of capital with interest (RCI pricing), of the operation period (OP pricing) and of marginal cost (MC pricing). Then similarities and differences among these three pricing methods existing in the transitional period are examined by a case in china. The indicate that it is important and inevitable to reform RCI pricing, to popularize OP pricing and to transfer to MC pricing.     

基于价格参考效应的生鲜电商供应链协调策略研究

考虑到生鲜电商平台销售过程中价格参考效应对消费者需求的影响,构建了价格参考效应影响下的消费者需求函数,研究由一个生鲜供应商和一个生鲜电商组成的生鲜电商供应链的协调问题。根据模型比较分散式决策与集中式决策下产品的最优定价、生鲜电商供应链成员的收益等,发现合作能够提高双方的利润,因此构建收益共享契约模型。结果表明,存在价格参考效应的情况下,生鲜产品的批发价格、契约参数、参考价格对于需求量的敏感程度对于生鲜电商最优定价、供应链成员收益有着不同程度的影响,同时契约参数的确定取决于生鲜电商、生鲜供应商在供应链的议价能力。     

Limitation and improvement of the equivalent capacity method for calculating the energy loss of distribution networks

Through the analysis of the equivalent resistance method, a limitation of the equivalent capacity method was presented. When the direction of power at the feeder source end was changing, the equivalent capacity method for handling small generations would produce a large power loss calculation error. An improved calculation method, one not based on a single equivalent resistance, was proposed. In this method, one day was divided into several periods (such as 24 h), so that the direction of power at the feeder source end for each period does not vary. The equivalent resistance and energy loss in each period were calculated. The sum of all energy losses provided the daily energy loss total. Numerical examples were used to verify the improved method.     

The Probabilistic Production Simulation for the Joint Dispatch of Multi Area Interconnected Power System

In this paper,a probabilistic production simulation for the joint dispatch of multi area interconnected power system is presented.The method evaluates the expected unserved energy of the joint dispatch system and further the other basic simulation indices,based on the probability density function of the unit available capacity and the multi area demand supply feasibility conditions,and the detail is showed by a four areas case.     

计及电网停电风险的输电线路动态融冰决策方法

电网发生大面积冰灾情况时,多条输电线路存在覆冰故障隐患,电网稳定运行受到严重威胁,需要提前制定输电线路融冰方案,合理安排融冰顺序。针对此问题,分析输电线路覆冰继续运行给电网带来的停电风险,将与待融冰输电线路相关联的变电站的电气主接线展开,将传统削负荷模型改进后应用于输电网与变电站主接线的组合网络,建立断路器可靠性模型,计算靠后融冰线路因继续运行的电网停电风险;利用计及风速及降雨影响的输电线路覆冰增长预测模型,计算输电线路的覆冰率,根据覆冰率门槛值确定待融冰线路集,基于覆冰严重度模型构建系统全局的覆冰指数指标;综合考虑电网停电风险及系统全局覆冰指数建立输电线路融冰紧迫度指标,动态更新待融冰线路并决策融冰顺序。最后,以IEEE RBTS系统进行算例分析,验证了所提方法的可行性与合理性。     

A DECOMPOSED OPTIMIZATION MODEL FOR POWER NETWORK PLANNING

This paper presents a decomposed optimization model for power network planning. The planning problem is divided into master problem to determine the investment decisions and subproblems to deterimne the operation decisions. In the proposed model, the effects of multi load levels,stochastic line outages,power loss cost and load curtailment cost on the investment decisions are considered. The results of the examples prove the feasibility and effectiveness of the proposed model.     

八地脚螺栓刚性塔座板的承载力

随着中国电网技术的发展,杆塔负荷越来越大,八地脚螺栓塔座板应用越趋普遍。但现有计算理论与实际情况不符,为了使八地脚螺栓塔座板的计算方法合理、可靠,通过试验对八地脚螺栓刚性塔座板承载力进行了研究,同时借助有限元对构件进行了参数化分析。结合经典力学理论、试验及有限元数据,提出了全新的计算方法,引入了等效计算宽度和有效力臂的概念,充分考虑了底板刚度,屈曲后强度和垫板对承载力的影响,对工程设计具有指导意义。     

Compensation trust evaluation model of grid service

It is difficult to distinguish the cheating and other malicious behaviours in the grid service trust evaluation. A trust evaluation model for grid service based on compensation is proposed.With market mechanism, service provider and demander present the expected profit and compensate price for their behaviours to maximize their own profit. The game theory is applied to balance the expected profit and compensate price. Based on the game theory, evaluation trade strategy achieves perfect Bayesian equilibrium. Service provider and demander can choose their own trade strategy to maximize profit. Theoretical analysis and simulation results show that the service demanders can abandon the cheating motivation voluntarily, while the service providers can make right decision to choose trust evaluation. Compared with the existing model, the precision and security of the trust evaluation is enhanced greatly, while the calculating and communication cost is reduced remarkably.     

Heuristic research and fuzzy evaluation for-post-faultrestoration in distribution networks

A heuristic research and fuzzy evaluation fault restoration algorithm for distribution network is proposed to quickly restore power supply for the regions where power supply is interrupted. The algorithm searches power supply paths by finding effective tie-switches and sectionalizing switches, and eliminates improper switch pair according to power flow calculation. During service restoration process, the problem is divided into self-healing restoration, whole-region restoration, sub-region restoration, load-transfer restoration and load shedding restoration. The algorithm takes switch operation times and customer priority into account, and consequently, obtains initial feasible schemes. Fuzzy technique is used to evaluate the schemes from minimal switch operation times, load transfer, feeder margin and maximal voltage drop. Weighted sum of four indices provides a good guideline for choosing the optimal scheme for restoration operation. Calculation results of a certain distribution network show that this algorithm is feasible.     

On the Extension of the Stock Model

Stock model of economical order batch is established under the objective of maximum total profit according to the hypotheses of constant demand rate.Based on these facts,the author suggests that the stock model of economical order batch is established under the objective of maximum total profit in system according to the hypotheses of demand rate's relying on selling price.From which one extended a model can be deduced.By using extreme-value theory,the model is proven mathematically and the method of solution is deduced for optimal order batch,optimal selling price and how to define optimal order cycle,and the sensitivity analysis has been made.One applied example is also given.     

Erosion Optimized Diagnosis of Brand Grounding Grid

To find the corrosion of the grid ,large area cutting has been adopting in practice for a very long time. But this method is blind, difficult and influences the system operating. The erosion diagnosis method in the past is effective for the smaller grid. To the brand ones, it can not take effect. The method of separating the grounding grid into several parts and diagnosing step by step is discussed by lots of simulation about middle or brand grounding grid erosion diagnosis. This method makes the brand grounding grid erosion diagnosis quick and truly without power cut and digging large area, satisfies the demand in practice. Putting this optimized diagnosis method into practice , the result is good.     

Improvement Algorithm of Generation Cost Based on Reliability

This paper discusses the influenced manner of reliability on bidding, and establishes the direct functional relationship among reliability, generation cost and electricity price in different risk of power generation. In this function model, the generation cost and the price could reflect the current reliability of equipment in a dynamic way. The generation risk is also considered in competitive bidding. The bidding strategy based on this model helps the power plant acquire the optimal benefit.     

Mechanical Properties of Regional Confined Rectangular Concrete Columns under Axial Loads

Based on experimentthatal results,we conclude that confinement in regional confined concrete(RCC) columns is more efficient than that in normal confined concrete(NCC) columns.As loads increase,NCC column sections tend to become round;the corner concrete in the core area may break;and,the strains of external stirrups tend to drop slightly after the peak load.RCC columns,however,remained thoroughly rectangular and the stirrup strain increased steadily.The failure mode of RCC columns was totally different from that of NCC columns.While NCC columns tended to fail in shear,followed b a rapid drop in load carrying capacity,the RCC columns developed gaps in their midsections and the columns separated into several slender columns.After a long deformation period,the RCC columns retained approximately 40% of their load carrying capacity.It can be expected that this characteristic may benefit the anti-seismic capacity of structures.     

NLPNN Model in Power Systems Reliability Evaluation

The purpose of a power system is to deliver the power the customers require in real time, on demand, within acceptable voltage and frequency limit, and in a reliable and economic manner. Using NLPNN (New Linear Programming Neural Network) model, the behavior analysis of power system under fault conditions is carried through. The stability and convergence theorems are set up to obtain the resolution for the problem of the load curtailment strategy. A new way is open up to evaluate the reliability of power systems and the great progress in calculation analysis model is achieved. The new calculation technique and theory foundation of reliability evaluation are supplied.     

Analysis on the Optimal Operation in Hydroelectric Station of Gezhouba

The optimal operation in hydroelectric station unit is me opumum problem,which include unit commitment,load distribution and unit maintenance. The authors research the optimal operation in units in hydroelectric station of Gezhouba by the genetic algorithm and dynamic programming to satisfy the demand of economic operation of Gezhouba. They arrange and organize the program of the units in r6ason to go for the better benefit and satisfies security, credibihty and high quality of electric production . These methods can work out the most optimum result. When the head of water and the flux is confirmed they can distribute the flux to the units to realize the optimal operation of the scheduling in Gezhotlba.     

Optimal model and algorithm for flexible job-shop scheduling problem based on demand time window

Aiming at the scheduling problem for jit delivery under the pulling type production, an optimal method for flexible job-shop scheduling problem (FJSP) based on demand time window is proposed. According to the demand time window of every workpiece, an optimal model for FJSP is constructed to maximize the average membership degree based on the completion time for every workpiece.Then, a tabu search algorithm based on multi-stage hybrid mutation is proposed and designed.To improve the convergence of the algorithm, inverse order mutation and gene segment swap mutation are used to find a good original solution, upon which gene swap mutation is used to find the optimal solution. The effectiveness of the proposed method is validated by applying to a multi-type and small-batch production manufacturing workshop.     

An asymmetric fault ride-through control method forPMSG wind turbine based onsuper-capacitors

With the rapid increasing interaction between wind turbines and power systems, wind turbines have to have the fault ride-through (FRT) capability to ensure the safe operation of power grid. In order to improve the asymmetric FRT capability of permanent magnet synchronous generator (PMSG) wind turbine, a novel control FRT method based on super-capacitors is proposed. In this method, super-capacitors are connected to the DC bus of AC-DC-AC converter via a bi-directional DC-DC converter, and the power processed by the super-capacitors is controlled to limit the increasing of the DC bus voltage of the AC-DC-AC converter in grid failure condition, and to reduce the 2nd order voltage ripple in the DC bus. Meanwhile, the proposed control method employs the grid voltage feed-forward approach to reduce the negative sequence current component in the grid side converter. According to the low voltage ride through (LVRT) standard, the selection of the super-capacitor capacity is also discussed, and then a mathematical model of the super-capacitor with the bi-directional DC-DC converter is established for designing the controller. Simulation results for a 1MW PMSG wind turbine by MATLAB show that the proposed control method reduces both the negative sequence current component in grid side converter and the 2nd order voltage ripple in DC link at the same time. The results also demonstrate that the asymmetric FRT capability of PMSG wind turbine is improved, which verifies the effectiveness of the proposed control method in this paper.     

Partition Algorithm of Power Network Based on the Optimum Clustering Principle

The paper construct the specimen of multi-dimensional space based on the definition of clustering, calculate the generator control sensitive to load and the Eulerian distance, partition the power system by the shortest distance method of clustering analysis. After the range of area num-ber is determined, the optimal area number and its validity is decided by Shannon function of entropy and Sugeno-Yasukaw rule. A case of IEEE 39-bus system is presented to verify the method.