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Energy and Power Engineering, 2013, 5, 612-615 doi:10.4236/epe.2013.54B118 Published Online July 2013 (http://www.scirp.org/journal/epe) Research of Security Constrained Dispatching for Monthly Generation Plan Rui Ge1, Hai-chao Wang2, Dun-nan Liu3 1Dispatching Control Center, State Grid Corporation of China, Beijing, China 2Dispatching Control Center, Anhui Electric Power Company, Hefei, China 3School of Economics and Management, North China Electric Power University Email: ge-rui@sgcc.com, wanghaichao@ahepc.com.cn, liudunnan@163.com Received January, 2013 ABSTRACT The dispatching for monthly generation plan is to manage the congestion considering the security constrains of the power grid, where the monthly generation plan is the result of vary monthly power exchange, including long-term pow- er contract, power exchange among provinces and generation constitu tion exchanges. The applicatio n of monthly secu- rity constrained dispatching is with significant meaning for the security and stability of power grid. This paper brings forward the purpose and contents of security dispatching and introduces the working procedure and mathematic models. At last, the practical example of the Anhui Province power grid is introduced to explain the models. Keywords: Direct Purchase by Major Users; Security Constrained Dispatching; Monthly Generation Plan 1. Introduction The medium and long-term contract transaction safe examination and the blocking management are mainly examine the electric transmission cross section transmit- ting capacity and satisfy the tendering space safely the load demand [1-3 ]. The Anhui Province accent must plan considered that power plant power capacity, peak load ability, the electrical network safe operation, the net woven net damages and so on factors, decided that the substitution electricity generation trades whether to be- come effective, and is responsible for the substitution electricity generation transaction arrangement imple- mentation which will become effective. The monthly security examination is the indicator to the electric quan- tity plan security constraint adjustment, its major func- tion is examines and adjusts the month electric quantity plan, causes it to satisfy the regional security constraint condition, here month electric quantity including de- composes to the month yearly contract, outside the power transmission contract as well as the substitution electric- ity generation tendering electric quantity. The medium and long-term safe examination’s implementation revo- lution regarding guaranteed that the electrical network safe operation, enhances the electric quantity plan the perform ability to have the important meaning [4, 5]. The needle return ing to p arents’ ho me electric qu an tity time span is big, the uncertainty strong characteristic, this article unifies Anhui electrical network characteristic, proposed that the electrical network monthly electrical energy plan safe examination’s content and the work flow, use the tie line race the average stable quota to take the regional security constraint condition to carry on the examination computation, and carries on the confirma- tion by the actual electrical network data. 2. Monthly E l e c t r i city Generation Plan Safe Examination Goal and Localization 2.1. Current Buys Sells the Electricity Transaction Pattern and the Market Me- chanism As shown in Figure 1, current Anhui Province Electric- ity company monthly transaction including the following several kinds: As seen in Figure 1, in buys in straight the electricity transaction take the province as the unit, has the follow- ing market main body: Figure 1. The big user buys the electricity transaction con- dition straight. Copyright © 2013 SciRes. EPE R. GE ET AL. 613 1) The provincial power grid company Responsibility with not to participation to this prov- ince buys the electricity the electricity generation com- pany to sign the order electricity contract straight, buys with other provinces electrical network sign both sides sells the electricity contract, and guaranteed that electri- cal network’s dispatch and the electric power are bal- anced; 2) Participate in direct purchase of electricity genera- tion companies Direct purchase of electricity by large users’ platform, users with large purchase contract entered into directly; direct power reduction of big users of electricity trade surplus space, with grid electricity sales contract signed. Current will participate in the big user buying the electricity the electricity generation company is straight in 2004 and the later new production, conforms to the national capital construction examination procedure and obtains the electricity generation service permit the thermoelectricity generation enterp rise (including nu clear power) and the hydraulic electro generating enterprise. Among them, the thermal power companies as stand- alone capacity of 300,000 kw and above business, hy- droelectric companies for stand-alone capacity of 10 ki- lowatts or more businesses. 3) Other provinces and Power Company Power trading with other provinces and cities mainly bilateral purchase and sale of electricity trading; 4) The province did not participate in direct purchase of electricity generation companies and signed the grid electricity sales contract. 5) Large users The large user may act according to own electric pow- er demand, the complete demand or a part, buys the elec- tricity platform and the electricity generation company straight through the big user signs buys the electricity contract directly, the surplus demand may also purchase to the electrical network company. 2.2. Monthly Electrical Energy Transaction Type Analysis Whatever Key Performance Indices are selected, they must reflect the goals of the business, they must be key to its success, and they must b e quan tifiab le (measurable). Key Performance Indices usually are long-term consid- erations. The definition of what they are and how they are measured do not change often. The goals for a par- ticular Key Performance Indicator may change as the busi- ness goals change, or as it get closer to achieving a goal. Impact of various ty pes of monthly energy fairs m onthly power plant planning, in which different transaction price of the contract, scheduling rights and other regulations also affect the monthly security correction. For satisfying outside power transmission contract, transaction with power plant between; The province in- side and outside power transmission tender the market transaction; Saves outside power transmission bilateral contract between the net and the power plant; Substitu- tion electricity generation transaction between power plant; Power plant increase electricity generation con- tract. 2.3. Monthly Security Examination Goal and Localization With the electricity trading institution s have been built at all levels, the monthly consumption of electricity market trading as the main form of the transaction. Scheduling is based on monthly domestic electricity power plants are given the full month of the total electricity generation. However, how does the electric quantity plan carries on the electrical network to examine safely, the direct rela- tion monthly plan execution’s feasibility, becomes the question which urgen tly awaits to be solved. The present solution is: ①The electric quantity examination way, soon electrical network’s electric power restraint conver- sion for the monthly electric quantity restraint, this way serious influence power plant entire month power rate; ②The electric power examination way, decomposes the various power plants’ monthly electric quantity into the electric power plan, then carries on the safe examination, but the electric quantity decomposition principle deter- mined with difficulty. 2.4. Security Check on the Contents of Anhui According to Anhui Province’s actual situation, this re- port proposed that Anhui electrical network monthly se- curity examination’s pattern is as follows: 1) The examination object -- power plant monthly buys the electricity plan straight Anhui monthly security check of the calibration grid target is based on the types of transactions monthly pow- er generation projects, including the province transac- tions: decomposition of the annual contract to replace the contract; province of: tie-line planning, delivery power contracts. New power plant signed monthly direct power schemes need confirmation through security check and adjust the order of security checking transactions by direct power to declare the order of execution. 2) Examination content -- four safe examinations Anhui electrical network monthly security examina- tion will carry on the following four examinations to various power plants’ electricity generation plan: Monthly total electric quantity examination: Forecast according to the monthly electricity consumption that carries on the safe examination to various power plants Copyright © 2013 SciRes. EPE R. GE ET AL. 614 monthly plan electric quantity, and carries on the safe adjustment according to the check result. On way to check the maximum: the maximum load forecast based on month, the maximum load on the out- put mode of the plant for security check; Month master curve: Forecast according to the month typical date 96 spot loads that carries on the decomposi- tion to the power plant monthly electricity generation contract, and considered that the unit overhauls, situa- tions and so on line overhau l, carries on day after day 96 model load diagram. 3) Anhui electrical network dist rict analysis si tes model We can introduce the conception of KPI to the analysis of electricity market, which is one of the most important tasks of market surveillance committee. According to the electrical network district analysis sites model's construction thought that may carry on the safe area division to Anhui electrical network, and estab- lishes the corresponding computation model. According to Anhui electrical network's geographic distribution characteristic and the safe stable regulations, Anhui elec- trical network may divide into A, B, C, D, E, F, G, H, I altogether 9 security district, in each security district contains the ration the power set and the system load, its analysis sites connection relations see also Figure 2: When concrete division safe area, needs to solve the following problem: a) Various power plants and safe area subordination relations; b) Each main load and safe area subordination rela- tions; c) Various transformer substations and safe area sub- ordination relatio ns. When divides the security cross section, needs to solve the following problem: According to the above safe area actual model, may carry on the simplification, obtains analysis situs model which the electrical network calculates, like Figure 2: a) To connect the different safe area the tie line race forms the security cross section; b) Determines between various tie lines and the cross section subordination relations. 4) Safe examination step and algorithm Anhui electrical network monthly security examina- tion may divide into the following four main steps: a) District load forecast The district load forecast is responsible to act accord- ing to the monthly safe area the division, forecasts vari- ous safe areas separately the electricity consumption or the load, including the following four targets: Various safe areas monthly electricity consumption; Various safe areas monthly valley even three time in- terval electricity consumption; Various safe areas month biggest load; Figure 2. Anhui electrical network safe examination com- puting network model. Various safe areas which month typical date 96 load diagram. b) The electricity generation plans the pre-decomposi- tion strategy According to the total electric quantity examination, three time interval electric quantity examination, the biggest load examination and 96 typical date curve ex- amination’s request, the power plant monthly plan carries on the decomposition to the province, satisfies the safe examination the need. c) District cross section safe examination algorithm There are two typical indices to explain the risk of ge- nerators’ bidding str at e gy. According to the safe area division, to between various safe areas’ tie line race, forms the security cross section. The distinction computation each security cross section may transmit capacity ATC; Decompose according to the district load forecast and various power plants plan, carry on the district electric power balance computation, ac- cording to the computed result, verifies each security cross section one by one actual transmission electric quantity and may transmit the capacity. d) Multi-criterion safe adjustment To surpasses the cross section to be possible to trans- mit the capacity situation, should the overall evaluation electrical network security goal, the economic target, the energy conservation goal, the contract progress goal and so on carry on the multi-objectives the overall evalua- tions, makes the optimized adjustment to the related dis- trict electricity generation plan, completes the safe ad- justment. Like Figure 3: 3. Example Analysis Below take Anhui electrical network some safe area as Copyright © 2013 SciRes. EPE R. GE ET AL. Copyright © 2013 SciRes. EPE 615 Table 2. After the adjustment, a area electrical network electric quantity balanced plan. an example, carries on the synthesis confirmation to the monthly electricity generation plan safe examination algorithm, and gives the monthly electricity generation plan safe examination the adjustment effect. According to the safe area which and the tie line race assigns define, follow the district adjustment the thought that before having given the adjustment, this safe area electric quan- tity balanced plan, see Table 1. Power rate Total load Tie line race 1 upper limit Tie line race 2 upper limit Tie line race 3 upper limit 20.1511.362.45 3.11 3.23 Looking from the electrical network actual operational aspect, after the revision electric quantity plan has the strong feasibility, has safeguarded electrical network's security reliability service, have received the movement personnel’s co nsi st ent hi g h prai se. Through to the power rate, always shoulders, the tie line race tidal current upper limit to carry on the electric quantity balanced to be possible to know that a area pri- mitive electric quantity transaction plans excessively high, the monthly power rate plan is bigger than always shoulders transmits the upp er limit sum total with various tie lines race: 4. Conclusions This article links to the provincial level electrical net- work reality, proposed the monthly electrical energy plan safe examination work’s content, the duty and the ex- amination method, lay th e rationale for Our country Pro- vincial level Electrical network Company monthly secu- rity examination work’s development. Anhui electrical network’s application example indicated that this article proposed the algorithm can propose the important crite- rion for the pre-electric quantity transaction plan, re- garding maintenance substitution electricity generation electric power market public, fair, fair principle, guaran- teed that the electrical network safe operation has the important meaning. 20.67 > 11.36 + 2.45 + 3.11 + 3.23 = 20.15 The actual execution had certain difficulty, after Table 2 has given the adjustment a area electric quantity bal- anced plan. This adjustment scheme scaled down in this safe area the power plant power rate. In guaranteed that under entire net power supply total quantity certain premise, changes by other safe area increases the electricity generation output. REFERENCES [1] H. C. Shi and H. S. Liu, “Application of Secure Active Power Real-Time Dispatching In AGC In Yunnan Power Grid,” Water Resources and Power, Vol. 27, No. 4, 2009, pp. 212-214. [2] L. L. Li, J. Geng, J. G. Yao and Z. L. Yang, “Model and Algorithm for Security Constrained Economical Dispatch in Equilibrium Power Generation Dispatching Mode Source,” Dianli Xitong Zidonghua/Automation of Electric Power Systems, Vol. 34, No. 15, 2010, pp. 23-27. [3] D. N. Liu, R. Q. Li, X. Q. Chen, et al., “Surveillance Indices and Evaluating System of Electricity Market,” Automation of Electric Power Systems, Vol. 28, No. 9, 2004, pp. 16-21. [4] D. N. Liu, X. Q. Chen, G. Y. He, et al., “Analysis and Coutermeasure for Suppliers’ Behaviors in Electricity Market,” Automation of Electric Power Systems, Vol. 29, No. 6, 2005, pp. 24-28. Figure 3. Anhui electrical network monthly security ex- amination flow. [5] Z. X. Chen, K. Xie, J. Zhang, Z. L. Yang, J. Liu and H. Wang, “Optimal Model and Algorithm for Day-ahead Generation Scheduling of Transmission Grid Security Constrained Convention Dispatch,” Dianli Xitong Zi- donghua/Automation of Electric Power Systems, Vol. 33, No. 1, 2009, pp. 10-13. Table 1. Before the adjustment, safe area electrical network electric quantity balance d plan. Power rate Total load Tie line race 1 upper limit Tie line race 2 upper limit Tie line race 3 upper limit 20.67 11.36 2.45 3.11 3.23 |