【作者】 周磊；

【导师】 孙淑琴；

【作者基本信息】 吉林大学 ， 电力电子与电力传动， 2009， 硕士

【摘要】 随着我国经济的发展,用电需求量越来越大,煤耗相对小、出力大、厂用电率低、每千瓦投资相对较省的大容量1000MW燃煤机组将越来越多地投入电力市场,这些大容量的发电机组今后将成为电力系统的主力机组。但大容量机组存在短路电流大、起动困难等问题,其中厂用电系统的可靠性问题更加突出。本文针对容量为1000MW的火力发电机组的特点,对几种不同电压等级和接线的厂用电方案进行技术经济比较,来确定最合理的厂用电接线方案。配电系统的可靠性关系到电能是否可靠运送到用户以及电能的质量问题,而电厂运行的可靠性关系着配电系统的安全运行,只有保证了发电厂厂用电的可靠,整个电网的安全运行才有保障。到目前为止针对火力发电厂厂用电系统可靠性仿真计算的研究在国内为数不多,本文基于马尔可夫算法对容量为1000MW火力发电厂厂用电接线系统进行尝试性的仿真计算,最后通过数据评估厂用电系统的可靠性优劣。短路故障电流的大小是选择电力系统中开断设备的决定性因素。采用国际最新的IEC909短路电流计算方法来对1000MW机组的三种厂用电接线方案进行短路分析,进而对方案的优劣做出评价。潮流是指电力网络中功率的流动,母线电压水平是潮流一个直接的体现,所以母线电压的波动范围是评价潮流优劣的标准。采用Newton-Raphson计算潮流法评估厂用电系统。在电机启动期间,正在起动的电机对于系统来说是一个连接在母线上的小阻抗负荷,它从系统中吸取很大的电流,相当于电机额定电流的六倍,使系统产生电压降,并对其它系统负荷的正常动作产生干扰,所以必须进行电机启动校验,采用静态起动模型,优化了堵转电流倍数的数值,在传统的设计中其值设定为6左右文中先在理论上通过分析计算后发现高压段电动机设定为4,低压段设定为5比较合适,由仿真计算验证了上述数据选择的正确性。最后对1000MW机组厂用电率和经济性也进行了计算,给出厂用电率和经济性的计算结果,以上数据为系统优化设计提供了依据。更多还原

【Abstract】 As the development of economy, the demand of electricity is increasing.So large province 1000MW coal-fired units that coal consumption is relatively small, effort is great , the rate of plant consumption is low and investment of per kilowatt is relatively small will be more and more applied in the power market,these large-capacity generating units will become the main power system unit. However, there are some problems such as short-circuit current is high, start-up is difficult and especially the reliabity of power system in the large-capacity unit.This thesis for the features of 1000MW thermal power generating units, compares several power programs in the technology and economy ,and then choose the the most reasonable power connection program. This paper will be expounded on the following:(A) Reliability. The reliability of power distribution system related to the reliability of electricity delivered to the user as well as the power quality problem,but the reliability of power plant related to the safe operation of power distribution system, only guarantee a reliable auxiliary power system, the safe operation of the entire power net may be guaranteed. < Factory Technical Regulation >provides that,in two units, if there are more than one alternate transformers are stared, the wiring system is reliable.The reliability means reliable start and safe shutdown of plant.This article bases on the Markov algorithm to attempt to calculate the thermal power capacity of 1000MW power plant unit wiring system ,finally assess the advantages and disadvantages of reliability of auxiliary power system through data.(B) Power flow (Voltage fluctuation). Power flow means electricity network power flow, bus voltage level is a direct reflection of the flow, so the the scope of bus voltage fluctuations is the standard to evaluate the flow merits. Power system flow calculation is a basic calculation, it is the basis of analysis for power system, its task is based on the given operating conditions to determine the power distribution network, power loss, as well as the bus voltage. Power flow calculation divides into on-line power flow calculation and off-line power flow calculation, the former mainly used for the trend-line power system control center, through the dynamics of power-line trend reflected the real-time scheduling. Power system uses the off-line power flow calculation, by simulates the design programs estimating the power flow situation. Newton-Raphson calculation is effective to solute nonlinear equations and has better astringency. N-R calculation for power flow calculation is bases on admittance matrix, because of the symmetry, sparsity and order to optimize the node ID of the admittance matrix, it has the obvious advantages on convergence, EMS, computing speed, so we choose the N-R calculation on plant-power system flow calculate.(C) Short-circuit current. It means when a certain bus short-circuit current the level in the flow of it, short-circuit level is to choose the size of power system equipment breaking the decisive factor. There are three-phase on the power distribution system, line- ground, line-line, line-line- ground, three-phase short-circuit current calculation is very important of the electrical engineering design. The current method of calculating short-circuit current, there are two main methods: < Power plant Technology Prescript>standard and GB/T 15544 standard. The latter equivalent using IEC 909(1988)standard (short form:IEC 909). This method is equivalent with a equivalent source to replace all of the voltage source. Short-circuit point is instead by equivalent voltage source cU 3, it is the only voltage source of the network, other power, such as synchronous generators, synchronous motor, asynchronous motor and the feed network is treated as a zero-electric potential, instead of internal impedance. Check motor start. When the motor start-up, it is a small impedance connecting in the bus load for the system, it absorptions a lot of current from the system, equivalents to six times of the motor rated current, allowing the system to have a voltage drop, interferes the other systems with normal movements. At present, the latest motor up-to-date algorithm including: dynamic motor to accelerate and static electric start. During the later one start and accelerate, make it start in locked rotor form, simulates the worst impact of the normal operation. We use static starting model, induct the conception of block running current finally the simulation data verify its correctness.(D) Plant power consumption rate and economy. The rationality of voltage selection is not only reflected in the reliability and safety on power supply ,but also reflected in the applicability and economy of the programs.We should consider availability of equipment, investment and so on.In this paper, we compare the two units` number of equipment and materials(transformer, common-closed bus, motor, cable and other main primary equipments). Finally simulates several cable programs, argument the merits of the programs according to data. It has a practical guide for the future power plant design and planning of the project.(E) Plant power consumption rate and economic calculation. In this paper, the scope of the economic comparison of the two units by the number of equipment and materials (transformer, busbar closed a total of boxes, motors, cables and other major one equipment) to carry out. Come to the conclusion, program one of the best economic. Three options in the same factory with the load, generating a total capacity of the same power plant, therefore the rate of three options are 4.99%. If the system did not use suction fan, booster fan and denitrification combined load, the system works for the 5.44% margin. This shows that the merger will be the motor is related to a point of order and system to meet the load requirements of the request of a small, lower power consumption rate of the plant, to that end, the motor is a combination of economic significance.Raised by several cable simulation program and the results of the data further argued the merits of the program, the paper recommended the program three wiring.更多还原