【作者】 施希；

【导师】 赵遵廉； 刘涤尘；

【作者基本信息】 武汉大学 ， 电力系统及其自动化， 2009， 博士

【摘要】 随着能源危机的来临以及人们环保意识的提高,核电在电网中所占的比重日益增加,核电站运行特性的研究对电网的安全稳定运行具有至关重要的意义。本文以新型大型压水堆核电站AP1000为研究对象,对反应堆中子动态过程和热传递过程进行了分析和建模,并对其在反应性阶跃扰动和冷线温度阶跃扰动下的动态响应进行了深入研究。仿真研究结果表明,由于核反应堆固有温度效应和中毒效应,堆芯具有一定的自稳定性,该固有特性保障了堆芯的安全,满足了核电站堆芯在初始设计时的要求。仿真曲线与工程实践数据一致,证明本文的堆芯模型真实有效。在堆芯模型的基础上,进一步结合核电站热线和冷线模型、一回路冷却剂温度模型、U型管温度模型和二回路蒸汽压力模型、一回路平均温度模型、汽机调速器和汽机系统以及反应堆控制系统。通过单机无穷大系统仿真发现,如果故障能迅速的清除并且核电站的控制系统正确动作,核电站能承受由电网引起的部分扰动,同时也验证了模型的正确性。核电站投运后一般是满功率带基荷运行,以期得到较大的经济效益,并要保证机组本身的安全稳定运行。但随着我国核电建设力度的加大,一旦核电装机容量占到电网的相当比例,核电机组若不具有一定的负荷跟踪的能力,将对电网的稳定运行带来较大影响。为保证电网的安全稳定运行,压水堆核电站通过功率控制系统调节反应堆的反应性以达到负荷跟踪的目的。本文研究设计的模糊硼浓度最优功率控制系统利用模糊控制器对棒速和硼浓度进行联合控制,在棒位移和硼溶液浓度的联合调控之间做出最优选择,以保证堆芯功率跟随负荷增减的同时轴向偏差AO在规定的范围内,堆芯功率均匀变化,避免功率畸变、局部过热、堆芯融化等危险情况发生。利用功率补偿通道加快了控制系统的响应速度,经仿真研究的结果证明其具有优良的负荷跟踪特性。将该控制系统模块接入所建立的核电站全系统模型,仿真结果表明压水堆核电站的负荷跟踪能力可满足电网的日负荷调峰要求。核电站接入系统,需要对核电站接入点的电力系统可靠性进行评价,分析电网强度,确定其作为外部厂用电源的可靠性。电网故障或扰动会导致核电机端电压、频率的变化,从而引起核电机组内部参数的波动。核电机组的退出将会导致系统失去大量有功功率,使故障情况进一步恶化。本文首先分析电网电压、频率波动时核电站内部参数响应,为保证核电站的安全得到核电退出电网孤岛运行的判据。通过仿真校验找出所有满足核电切机判据的预想事故,统计该故障发生概率从而判定电网是否满足国际原子能机构IEAE对核电接入电网的要求。针对核电不同接入方式进行仿真模拟,由仿真结果分析不同接入方式下的稳定程度。结果表明：独立送电,与附近的送端系统相连送电以及规模打捆外送三种方式中,后两种方式优于第一种方式,而采用与附近送端系统相连或打捆式送电方式,则需根据具体问题进行具体分析。核电站虽然前期投资大,但由于其环保上的优势、逐渐提高的安全稳定性和调频调峰特性而得到越来越多政策上的支持。传统的电源规划问题逐渐从经济利益考虑的单目标优化问题演化为需要考虑到决策者和专家意见的多目标优化问题；而且由于多目标电源规划问题维数高,非线性、约束条件多等特点而难于求解。本文提出一种改进Pareto适应度遗传算法IPFGA针对多目标新能源联合电源规划进行求解,IPFGA在遗传算法基本思想的基础上利用模糊决策选取适当的交叉率和变异率,双倍排序原则决定染色体的适应度值,并利用种群规模自适应密度估计防止算法过早的局部收敛。通过算例分析发现该算法与其他算法得到一致的Pareto Front解,证明该算法真实有效,且更好地防止遗传漂移、保持群体多样性的同时提高搜索效率,既避免了收敛到局部最优解也提高了计算速度。该算法可根据政策对核电厂的不同扶植力度快速找到适合当地情况的最优解,且具有普适性。在安全稳定性结论的基础上,结合模糊层次分析法和专家群组决策系统,利用多个专家经验对核电接入电网方式的多方面的优劣进行了综合分析和比较从而得到最终接入方案。该思路和方法在核电接入电网的前期规划中有着重要的指导意义。更多还原

【Abstract】 With the advent of the energy crisis and increasing awareness of environmental protection, the proportion of nuclear power in the grid increases, which makes the studies on nuclear power plant operating characteristics of critical importance in safe and stable operation of power grid. The current PWR (AP1000) nuclear power plants were taken as the research subjects in the paper, the neutron dynamic process and heat transfer process in the reactor were anaylyzed, and the modeling of reactor core was implemented. Dynamic responses of the NPP core under the input of step disturbance of reactivity and cool-line temperature were simulated, and the simulationresults showed that, owing to the temperature effect and poisoning effect of the NPP core, reactor core is endowed with certain self-stability which protects the security of the NNP core and meets the requirements of the initial design. Being consistent with the historical data, the simulation further backs the proposed NPP core model. Based on the NPP core model, various models were integrated as a comprehensive package, including nuclear power plant hot and cold-line model, first loop coolant temperature model, U-tube temperature model, second loop vapor pressure model, first loop average temperature model, steam turbine and steam turbine governor system, and reactor control system. Through the simulation of single machine infinite-bus system, the conclusion was drawn that if the fault is cleared promptly and the NPP control system works well, the nuclear power plant can accept certain disturbances from the power grid. Moreover, this simulation validates the model.The nuclear power plant, when completed, generally keeps running at full capacity in order to obtain much greater economic benefits, and alternatively, ensure the stable operation of its own security unit. However, along with the rapid development of China’s nuclear power construction, it is said that the power line will be heavily affected once the installed nuclear power capacity accounts for a considerable proportion of the grid, or fails to conduct certain load tracking. To ensure the power grid operated in a secure and stable manner, load tracking can be realized by using the power control system and regulating the reactivity of the reactor in PWR nuclear power plants. This paper deals with the fuzzy optimal power control system of boron concentration by using fuzzy controller as well as the rod speed and boron concentration. In doing so, the rod shift and boron concentration would be effectively regulated, Furthermore, the optimal choice is to be made to ensure that together with the increases or decreases of core power, Axial Deviation (AD) is guaranteed to change within a permitted range, and the reactor core power makes even changes to avoid the power distortion, local overheating, core melting and other hazardous incidents. The control system can accelerate the response speed by virtue of the power compensation channel, which has been defined by the Matlab for its excellent load tracking capacity. Connecting the self-defined control system model into the Nuclear Power Plant-wide System Model, simulation result demonstrates that the load tracking capability of the PWR nuclear power plant can meets the power requirements of the daily peak load.To connect the NPP into the whole power system, it is necessary to evaluate the reliability of the power system at the access point for NPP. This includes analyzing the intensity of electricity grid, and the reliability of it serving as an external power supply plant. The power grid malfunction or disturbance may lead to instability of the terminal voltage of NPP and grid frequency, which may cause the fluctuations in intrinsic parameters of nuclear power generating sets. Also the withdrawal of nuclear power units will cause the system to lose substantive active power, making the malfunction even worse. In the paper, the response of the intrinsic parameters of nuclear power generating sets is analyzed during the fluctuation of grid voltage and frequency. All the anticipatory accidents are found out by simulation when the criterion of NPP disconnection is met, and the probability of the ones is evaluated to determine whether the power grid meets the standard of IEAE. Different access ways of the NPP were simulated and stability margin of the access ways were analyzed based on the simulation results. The results demonstrated that in the three transmission modes:independent transmission mode, bundling power transmission mode, connecting the huge power supplier with sending terminal. The latter two is better than the first one. Whether to adopt the second mode or the third one depends on concrete issue.Although it has witnessed a huge fore-investment for nuclear power plant, more and more policy support from the government can be found due to its environmental-friendly concept, increasing security and stability, as well as frequency and peaking regulation. Economically, the traditional power supply planning has been shifted from individual optimization to multi-objective optimization by taking account of the ideas from the decision-maker and experts. However, it remains unsolvable since the multi-objective planning is labeled by high dimensionality, nonlinearity and multi-constraint condition. An improved Pareto fitness genetic algorithm (IPFGA) was proposed in this paper to deal with GEP problems. IPFGA is based on the basic concept of genetic algorithm, and decides the crossover rate and mutation rate by applying fuzzy system. In the genetic algorithm, double ranking strategy (DRS) is used to decide the fitness value, and uses population size adaptive density estimation (PSADE) to avoid premature local convergence, by which the same Pareto Front is obtained as other algorithms, and the effectiveness of the proposed algorithm is proved. Compared to other algorithms, IPFGA can effectively prevent genetic drift and maintain population diversity; in the meanwhile, it can improve the search efficiency, avoid regional optimal solution and at last, but not the least, promote the calculating speed. IPFGA can be easily applied to find the optimal solutions for various utilities via various expert opinions, and can be well and widely adopted. Based on safety stability conclusion, combining with fuzzy analytic hierarchy process and expert group decision-making system, the final access way is decided by comprehensive analysis and comparison of the NPP transmission mode. The ideas and methods are of important guiding significance at pre-planning of the connection with the power grid of NPP.更多还原