【作者】 黄凯；

【导师】 高山；

【作者基本信息】 东南大学 ， 电气工程， 2018， 博士

【摘要】 电网的安全经济运行一直是电网运行调度关注的重点,自动电压无功控制系统也在各国电网中得到越来越广泛的应用。当前影响电压无功控制功能实用性的主要问题有以下几点:一是基础数据的准确性,这是一切后续分析和优化的基础;二是电网不确定性所造成的电网断面相对于静态优化断面的偏离,对此不作处理,优化结果也可能不适宜实际控制执行;三是各地新能源场站的陆续接入对电网的运行控制挑战,一方面新能源场站的接入对原有的无功分区产生影响,另一方面,区域电网原先的调节手段主要以变压器挡位、容抗器投切等离散控制为主,当前则需要考虑它们与新能源场站无功连续量调节的协调;四是工程实践环节的处理,要保证电压无功控制系统的模型能时刻和电网物理实际保持一致,不能因为维护的错误和新模型的发布造成控制的软件运行的中断。只有解决了上述问题,电压无功控制系统才能真正成为可实际运行的可靠系统,为电网的安全经济运行保驾护航,让其成为电网调度运行的可信赖的控制手段和工具。针对以上影响电压无功优化控制实用化的关键问题,本文分别从数据准确性处理、考虑不确定因素的优化潮流、无功分区、协调新能源厂站的区域电网电压无功控制、更新的电网模型即插即用和软件不间断运行等几个方面进行了深入研究:研究提升断面基础数据准确性的方法。采用基于WAMS数据相关性识别的量测时差补偿混合状态估计和基于AGC镜像系统的调度员潮流计算方法,来获取与真实系统更为一致的基础数据断面。对采集周期中SCADA数据和WAMS数据的相关性进行计算,以相关性最大的WAMS数据时标作为电网断面时间,依据相关性将SCADA量测节点安装有PMU节点的数据进行分区,同分区的采集数据用相同的时差补偿,可以有效处理混合数据的同时性问题;此外,设计了镜像AGC系统,可以真实体现发电机的一次调频和二次调频的实际影响,在潮流计算中考虑系统的频率调整效应,尤其是AGC二次调频对潮流的影响,可以在扰动情况下计算出更符合实际物理断面的潮流分布;这两方面的工作为获取电网准确的潮流断面打下了坚实的基础,让电压无功控制有一个更准确的数据断面。研究基于不确定性理论的三级电压优化控制算法。由于电网始终处于动态变化中,即使是采用了相对准确的电网数据断面进行优化计算,由于计算结束后电网的运行断面已经偏离了之前优化时刻的断面,优化结果也可能不适宜实际控制执行。因此,本文基于负荷无功和PV节点电压幅值的不确定性建模,采用场景分析法来描述电网实际状态相对基础断面的随机性,利用正态分布计算各典型场景发生的概率,并建立全场景下以网损最小和电压调节方向偏差最小为目标函数的无功优化模型;通过引入模糊集理论来模糊化确定性问题,之后采用最大满意度法把多目标模型转化成单目标模型,并使用改进了的粒子群优化算法进行问题的求解。研究电压无功实时动态分区方法。从实际系统运行需求出发,在最短路径算法的基础上进行了研究,并提出了基于图论的电压无功控制实时动态分区算法,对新能源场站的等效外特性进行了分析,将其作为一个无功调节控制的常规调节源考虑,与电网调度中对其定位保持一致,从而可以继续沿用相关的电气距离求解算法,再通过实时分析参与控制的电源点无功特性对电压的影响进行分区,更能体现无功控制源对分区的作用。本文的广度优先搜索算法时间复杂度为O(n),成功地把搜索单源结点的最短路径时间复杂度从O(n2),缩小到O(n)量级,显著地提高了计算效率;此外,对边界节点按灵敏度进行校核和分区调整,可以避免纯图论算法不考虑潮流分布影响的缺陷,使得分区结果和传统理论更具可比性,也更合理。研究协调新能源场站的地区电网电压无功控制系统。在预测风光输出特性和负荷量的基础上,提出了一种采用模糊逻辑算法的地区电网电压无功协调控制方法,分别设计了离散量和逻辑量的模糊控制逻辑和规则,将综合电网运行经验的控制策略转换成一种层次型模糊推理,既可以对离散量进行控制也可以对新能源厂站的连续量进行控制,同时,设计了离散量和连续量的协调层,可以在实际运行中对两者进行协调控制。该控制系统既可以处理挡位调节、容抗器投切等离散量,也可以对新能源场站的无功出力连续量进行调节,有着很好的实用价值。从计算机内存管理和模型维护两个维度研究控制软件的不间断运行问题。大型控制软件在实际运行中需要解决模型的在线更新问题,要求电网模型改变时重要的控制进程不能中断运行。本文提出源端维护技术来解决变电站模型变化后新模型的“即插即用”难题,通过扩展了二次设备的全景模型,可以实现IEC61850模型到CIM模型的唯一转换,此外还定义了主站和子站源端维护的完整流程,并扩展了IEC60870-5-104协议来传输交换文件,使得该技术具备使用价值。本文还在计算机内存管理技术的基础上给出了在线装库的原理,通过计算机进程的指针切换来访问新的电网模型,达到运行不中断的目的。离线维护、在线装库从计算机操作系统调度角度解决软件的不间断运行问题,通过这两方面的工作,可以使得无功电压控制软件在实际系统中真正做到不间断运行,有着重要的工程价值。更多还原

【Abstract】 The safe and economical operation of power grid has always been the focus of grid dispatching agency,while automatic voltage and reactive power control system has also been applied more and more widely all over the world.The main issues that impair the practicability of voltage reactive power control function are as follows: Firstly,the accuracy of the basic data,which is the basis for all subsequent analysis and optimization;Secondly,the deviation(caused by power grid runtime uncertainty)from power flow snapshot on which the optimization calculation is performed,without handling this,the optimal results may not be suitable for the actual control execution;Thirdly,the challenges for the operation and control of power grid as the growing renewable energy sources are connected to our grid,on the one hand,it has an impact on the original reactive power partition.on the other hand,the original adjustment method of the regional power grid is mainly based on discrete control such as transformer tap-changer and compensator or reactor switching,but now,their coordination with the reactive power regulation in new energy stations needs to be considered.Fourthly,in engineering practice,we must ensure that the system model can persistently be consistent with the actual physical grid,furthermore,computer processes must not be interrupted due to maintenance errors or the updating of new power grid models.Only by solving the above problems can the voltage and reactive power control system truly convert the research theory to a reliable system,which can provide safe and economical operation service for the power grid and make itself a trustworthy tool for grid dispatching.In view of the above key issues that affect the practical application of voltage and reactive power optimization control,this paper analyzes the data accuracy,the method of optimization considering the uncertain factors,reactive power partitioning,coordination method for new-energy plant station in regional automatic voltage control system,plug and play of new power grid model and uninterrupted software operation method:Methods of improving the accuracy of power flow snapshot data are proposed.Based on the WAMS data correlation recognition algorithm and AGC mirror system,the mixed-measurements state estimation method considering time lag effects and a new power flow calculation skill are designed to obtain the more accurate basic power flow snapshot data.The correlation indexes between SCADA and WAMS measurements in the same acquisition cycle are calculated,and the WAMS measurement timestamp with the best relevant correlation index is taken as the grid snapshot time,so the SCADA measurements are partitioned according to their correlation with the PMU measurements.For the datum in the same partition,they will be compensated the same time lag in state estimation calculation,and the method can effectively deal with the simultaneity problem of mixed measurement state estimation.In addition,considering the effect of frequency adjustment of the system in power flow calculation,especially the influence of AGC secondary frequency regulation effects on active-power flow,we can get a more accurate power flow snapshot matching the reality of power grid,especially when a disturbance occurs.The above two methods lay a solid foundation for voltage and reactive power control to get an accurate calculation case.The three-level voltage optimization control algorithm based on uncertainty theory is studied.Because the power grid is always in a dynamic state,the optimal results may not be suitable for the actual control execution even if the calculation is based on the above relatively accurate power flow snapshot,since the deviation cannot be avoided.Therefore,in this paper,the uncertainty is modeled by reactive power of energy consumers and the voltage amplitude of PV buses,and the scene analysis method is used to describe the randomness of the actual state of the power grid relative to the basic snapshot case.The normal distribution is used to calculate the probability of occurrence of each typical scene,after that,the reactive power optimization model used to minimize the network loss and the voltage deviation is built.First,the deterministic problem is fuzzified according to the fuzzy set theory;then the multi-objective model is transformed into a single-objective model by using the maximum satisfaction method;finally the improved particle swarm optimization algorithm is used to solve the problem.Grid partition method for voltage and reactive power control is also studied.According to the actual system operation requirements,the research is based on the shortest path algorithm.A real-time dynamic partitioning algorithm based on graph theory is proposed and the equivalent external characteristics of the renewable energy source are analyzed.Considering them as routine regulation source of reactive power can match the engineering practice,moreover,relevant algorithms of electric distance can still work.In grid dispatching,their influence on voltage and reactive power is calculated during real-time analysis,which can better reflect the effect of reactive power source on the zoning.The breadth-first search algorithm in this paper has a time complexity of O(n)and successfully reduces the shortest path time complexity of search single source node from O(n2)to O(n),which improves the computational efficiency significantly.In addition,checking and adjusting the sensitivity of the boundary nodes in a grid can avoid the defect that pure graph theory does not consider the impact of power flow distribution,making the partitioning result more comparable and more reasonable than the traditional theory.How to coordinate renewable energy plants in a regional voltage-reactive power control system is studied.Based on the prediction of active power output of load and solar energy,a method for regional grid voltage and reactive power coordination control,based on fuzzy logic algorithm,is proposed.It designs fuzzy rules for both discrete and continuous control facilities respectively,and it converts the control strategy of comprehensive grid operation experience into a hierarchical fuzzy inference,and can deal with not only the discrete control facilities but also the continuous control facilities of renewable-energy plants.At the same time,the discrete and continuous coordination layer is designed,which is effectively put into practice.The control system can handle discrete quantities such as power transformer tap-changer,compensator or reactor,etc.,and can also adjust the continuous output of reactive power of new energy stations,which has good practical value.From the two dimensions of computer memory management and model maintenance,the problem of uninterrupted operation of control software is studied.Large-scale control software needs to solve the online update problem of the power grid model in actual operation,and the important control process must not be interrupted when the power grid model is changed.This paper proposes the source-based maintenance technology to solve the "plug-and-play" problem of the new model after the change of it.By importing the panoramic model of the secondary device,the unique conversion of the IEC61850 model to the CIM model can be realized.The complete process of source-based maintenance between the substation and master control center is designed,and the IEC60870-5-104 protocol is extended to transmit the exchange file,making the technology useful.This paper also gives the principle of model publishing based on the computer memory management technology,accessing the new grid model by the pointer switching of the computer process,to achieve the purpose of uninterrupted operation.“Offline-maintenance,online-publish” technique solves the uninterrupted problem,while the source-side maintenance technology solves the new model " plug-and-play " problem.Through these two aspects of work,we can make the reactive power voltage control process in the actual system truly uninterrupted.It has important engineering value.更多还原