In modern power systems, power quality issues are becoming increasingly severe, and the additional line losses they cause are crucial for accurately evaluating theoretical line loss rates. Accurate calculation of theoretical line loss is the first step in line loss analysis. However, due to the complex topology of low-voltage distribution networks, traditional physical model-based methods are often unsuitable. To address this, artificial intelligence-based big data methods are used to model the complex nonlinear relationships between various influencing factors and theoretical line loss, enabling fast and high-precision calculations. In this study, all relevant factors, including power quality indicators, are considered. Grey relational analysis is applied to evaluate the significance of each factor, and cross-validation is used during feature selection to identify the input dimension with the lowest mean squared error (MSE). Based on the selected data, theoretical line loss is calculated using three algorithms: a particle swarm optimization (PSO)-based random forest, a backpropagation (BP) neural network, and a support vector regression (SVR) model. The PSO-based random forest is ultimately selected as the final model due to its superior performance. Simulation results from real-world low-voltage samples confirm the effectiveness and practicality of the proposed method.
In the context of the rapid development of electric vehicles(EVs),to guarantee the stable operation of an en-ergy transport system under typhoons,a repair and restoration strategy considering the highway network-distribution net-work coupling is put forward.The interactions between road traffic and various basic parameters of the distribution net-work under typhoons are quantified through modelling the highway distribution network.The probability of faults in the service area and the road traffic flow are calculated,and the real-time statuses of road and EVs are calculated and ana-lyzed considering the vehicle-road coupling relationship.On the basis of analyses,the repair and restoration strategy for highway distribution network is proposed.First,the site selection of a repair warehouse is carried out before the disas-ter.Second,the microgrid in the faulty service area is supplied with emergency power supply through resources such as distributed energy,energy storage and EVs.Finally,the impact of road traffic is taken into account,and the repair paths of repair teams are optimized to achieve a rapid recovery under faults.An actual highway distribution network in one area is selected to validate the effectiveness of the proposed repair and restoration strategy.
为保证现代电力系统配电网的安全稳定运行和供电能力,需要快速获取配电网准确的实时状态进而对系统进行动态分析、评估和控制.本文构建了复数域下基于同步相量测量的配电网线性状态估计模型,考虑节点注入约束提升了测量的冗余性,分析同步相量测量的误差特点并提出复数域最小二乘法求解状态估计问题.面向实际应用需求,通过分析测量残差提出一种权重自适应调整算法,以及一种不良数据辨识和校正的方法.仿真结果表明,所提方法能有效提高配电网状态估计的准确性、实时性和适用性.
为有效提高各发电主体的收益并促进发电侧碳减排,提出基于合作博弈的可再生能源-化石能源机组发电联盟参与电-碳-绿证交易的双层优化模型.首先,分析可再生能源发电机组和化石能源发电机组参与电-碳-绿证市场的方式,基于信息间隙决策理论IGDT(information gap decision theory)构建考虑现货价格不确定性的发电联盟鲁棒优化模型,作为双层优化的上层模型.接着,在下层建立电力现货市场出清模型、阶梯式碳交易模型和基于古诺模型的绿证市场交易模型,基于KKT条件将下层模型转化为约束条件并纳入上层模型.然后,构建基于Shapley值法和改进核仁法的发电联盟收益分配模型.最后,以IEEE 14节点系统为例进行算例分析,验证了所提模型的有效性.
为检验新能源场站参与电网调频控制的实际效果,提出一种基于动态模式分解的新能源场站虚拟惯量与有功-频率下垂系数估计方法.首先,分析了新能源机组有功-频率表达式的重构原理,揭示了场站虚拟惯量和有功-频率下垂系数同系统状态特征之间的解析关系;在此基础上,构建了基于动态模式分解算法的新能源场站频率特性估计模型,利用提取出的系统特征重构了场站的有功出力和频率变化,将非线性微分方程转变为线性方程组进行求解,简化了场站虚拟惯量和有功-频率下垂系数的估计难度.最后,在PSCAD/EMTDC中搭建新能源场站接入IEEE 9节点系统和IEEE 68节点系统,验证了所提方法的有效性和准确性.
为缓解风电不确定性对电-气综合能源系统IENGS(integrated electricity-natural gas system)运行的影响,基于可信性理论提出一种模糊机会约束-区间最优能流计算方法.首先,在综合考虑电力网络与天然气网络能流耦合的基础上,针对风电出力的不确定性,构建了基于可信性理论的电力网络模糊机会约束模型,并推导出模糊机会约束的清晰等价类.然后,考虑风电出力的不确定性直接影响天然气网络运行,建立了基于可信性理论的天然气网络P2G设备和燃气轮机区间优化模型,并将含有非线性Weymouth方程的天然气网络模型等价转化为混合整数二阶锥规划模型.最后,以IEEE 33节点配电网和20节点天然气网络组成IENGS为例,验证了所提模型对抵御风电不确定风险的有效性.
In order to solve the problem that the cascaded H-bridge photovoltaic grid-connected inverter with large power overmodulates due to the unbalanced input power， which leads to the grid current distortion， In this paper， a new control method is proposed. By introducing an appropriate amount of fundamental wave to the overmodulated unit and compensating the introduced fundamental wave to other non-overmodulated units， the influence of the fundamental wave introduced in the overmodulated unit is offset.The proposed method can extend the modulation range to 1.27， and broaden the operation range of the stable domain of the cascaded H-bridge grid-connected photovoltaic inverter.
为应对新能源对频率支撑能力的削弱和大容量直流闭锁带来的频率冲击,需要进一步研究受端电网频率紧急控制策略.基于详细调速器和负荷模型,分析多维因素影响下的频率特性,把影响频率稳定的多维度因素映射至单一因素表征的低维空间,提出适应高比例新能源和大容量直流接入的频率紧急控制策略,并结合精准切负荷系统扩容场景,提出适应大区电网省间功率交换的两类可中断负荷分配方案.基于实际电网的仿真,验证了所提策略的有效性.
新能源接入含大量非线性负载的配电网,使其背景谐波更为复杂,甚至导致谐波谐振,严重影响配电网稳定运行.准确提取宽频振荡扰动及背景谐波特征参数是谐波振荡识别与治理的关键技术.针对传统的Prony算法提取扰动信息精度易受噪声与有效秩阶数的影响,提出奇异值分解法降噪法改善宽频振荡扰动信号质量.基于二阶导数理论的矩阵奇异值排列方法,选取合适模型阶数,提高背景谐波参数的辨识精度.仿真结果验证了所提算法的有效性.
The national "double carbon target" puts forward higher requirements for the economy and low carbon of the comprehensive energy system group， how to balance the economy and low-carbon of multi-agent integrated energy system has become an important research content. Therefore， this paper proposes a multi-agent integrated energy system low-carbon economic operation strategy based on the operation level and market level. Firstly， the Operation Mode and control model of cogeneration units with adjustable heat-to-power ratio are proposed， and then a two-stage stepped carbon trading model based on quota sharing mechanism is proposed， guide multi-agent integrated energy system to control carbon emissions. Finally， the minimum sum of energy purchase cost， carbon transaction cost， new energy disposal cost and energy storage plant investment and operation cost is taken as the objective function， which is solved by piecewise linearization and transformed into mixed integer linear programming problem， by setting up contrast operation scenarios， the low-carbon， economic and effectiveness of the proposed strategy are verified， and the sensitivity analysis is carried out to dig deeply into the internal power of low-carbon system， with a view to providing a theoretical reference for regulatory decision-making.
为响应"碳达峰、碳中和"号召,合理分配综合能源系统中各主体的利益,提出基于主从博弈的综合能源系统氢储能和碳捕集协同优化策略.首先,建立主从博弈模型,其中园区运营商为主从博弈的上层领导者,能源供应商、储能运营商和负荷聚合商为主从博弈的跟随者.其次,将包含氢储能和碳捕集的园区综合能源系统交易决策模型嵌入主从博弈框架下,利用改进的差分进化算法结合二次规划的分布式均衡方法求解.最后,算例验证了所提优化策略对降低碳排放、充分消纳风光资源、提高储能收益的有效性.
为应对大规模分布式电源DG(distribution generation)接入给配电网带来的挑战,考虑DG出力的不确定性以及电网储能投资成本的有限性,提出基于信息间隙决策理论IGDT(information gap decision theory)-机会约束的配电网最大DG可开放容量评估方法.首先,以最大化DG可开放容量为目标,综合考虑储能投资成本以及节点电压和线路容量机会约束等约束,建立基于IGDT-机会约束的配电网最大DG可开放容量评估模型;其次,对IGDT模型中的max项、机会约束以及网络重构等相关约束进行转化,并利用Cplex求解器对转化后的混合整数线性规划模型进行求解;最后,通过某地区有源中压配电网实例分析,验证了所提方法的有效性.
针对分布式储能中蓄电池组与直流母线互联的应用场合,提出一种具有高效、宽电流调节范围的改进电流型LC并联谐振双向隔离DC-DC变换器.通过对该变换器简化模型的建立和时域上对该变换器谐振电感电流、谐振电容电压和输出电感电流的推导,得到以平均值表示的电压增益曲线和电流传输比曲线.结果表明,提出的变换器在储能应用中具有较宽的电流调节范围,因此,该变换器用变频调制即能实现对储能充放电的控制.最后,搭建一台7.5 kW、50 V转300 V的实验样机,验证了前述分析的有效性.
Introducing flexible ramping products（FRP） into the market to improve the flexible regulation ability of the system is the key to cope with the high proportion of new energy grid connection. However， there are some problems that the demand of flexible resource （FR） is not reasonable and the traditional power generation measurement resources cannot provide sufficient flexible adjustment capacity. Based on the non-parametric kernel density estimation theory， a dynamic generation method of FR demand uncertainty interval was proposed， and a two-stage optimization model of day-ahead real-time market involving energy storage was constructed to solve the problem of insufficient flexible adjustment ability of power generation side resources under the worst scenario of FR demand. In the day-ahead stage， the minimum cost of electricity purchase is taken as the goal， and the combination of each unit is obtained by solving the model， and then the flexible adjustment ability of the system in each period is obtained. In the real time phase， the total operating cost of the system after the FRP service is considered as the minimum as the goal， to solve the problem of insufficient flexible adjustment ability of the system under the worst FR demand scenario， and to find the economical optimal solution. The results show that the proposed model is beneficial to improve the absorption capacity of wind power and reduce the operating cost of the system.
Due to communication failure or human factors， a large number of abnormal data will be generated by wind turbines during actual operation， which will have a great impact on working condition evaluation and output power prediction. Therefore， it’s necessary to process the abnormal data of wind power. By analyzing the characteristics and the causesof wind powerabnormal data， this paper proposes a method of wind power abnormal data identification based on the multi-model parallel integration framework. The method constructs an abnormal detection model pool based on the Isolation using Nearest Neighbor Ensemble method and the Local Outlier Factor method， then screening and merging twice through the parallel integration framework，finally obtain the final recognition result.Then， using the actual data sets of different wind farms for verification，and compared withthe single Isolation using Nearest Neighbor Ensemble method， the single Local Outlier Factor method and the sequential combination method.The results of numerical examples show that the proposed method can effectively identify all kinds of abnormal data， improve the accuracy of wind power prediction model， and has strong universality.
合理的光伏安装方案有利于降低配电系统的供电成本和提高能源利用率,因此需要根据供电经济性指标确定配网中分布式光伏的最佳接入容量.提出一种基于配网运行裕度的光伏最佳接入容量评估方法.该方法利用配网运行裕度信息,把高维的光伏多节点并网优化问题降至1维的光伏总接入容量优化,且利用分布式调度实现了不同主体的协同运行.通过对改进的IEEE 33节点系统开展算例分析发现,根据所提方法确定的光伏最佳接入容量超过了配网最大负荷与线路容量之和,为高比例分布式光伏接入配电网奠定了理论基础.
针对高比例可再生能源接入下电力系统惯量水平持续降低、弱频率调节能力会危及电网安全运行等问题,提出一种区域新能源电力系统自动发电控制AGC(automatic generation control)调频容量实时评估方法,以确定控制区的AGC调频能力分析需求.首先,依据AGC调频容量考核标准,梳理调频容量的主要影响因素,并获取调频容量、调频标准差与调频表现间的联系.其次,综合应用传统机组、负荷、新能源、联络线历史数据,基于极限学习机ELM(extreme learning machine)模型预测调频标准差,利用调频表现达标概率分布确定区域电力系统的调频容量.最后,以河北某电网为例进行AGC调频容量的评估,验证了所提方法AGC调频容量更小,调频表现更优,具有更好的安全性和经济性.
为确保电网频率安全稳定,混合储能联合光伏主动参与电力系统一次调频已成趋势,为此提出了一种混合储能联合光伏发电的一次调频控制策略.针对储能传统定系数下垂控制存在的储能易发生过充过放的问题,提出了储能自适应变系数下垂控制;为了充分利用2种储能的不同特性,提出了频率偏差自适应分配方法;同时设计了光储耦合控制模块,以弥补光伏功率备用容量和锂电池储能调频功率有限的不足.在Matlab/Simulink仿真平台进行不同负荷扰动场景下的仿真实验.仿真结果表明:所提控制策略可以显著提升光伏系统主动一次调频性能及其适应性.
为建立一个清洁低碳、安全稳定的能源系统,提出了基于绿证-碳交易机制的氢能利用综合能源系统多时间尺度优化调度策略.首先,为发挥氢能高效清洁的作用,建立电解槽热氢联产模型.其次,为降低系统的碳排放量,分别构建绿色证书交易机制和奖惩阶梯型碳交易机制.最后,为降低源-荷预测误差对系统运行的影响,构建基于模型预测方法的日前-日内-实时多时间尺度的优化调度模型.算例分析表明,所提模型能有效降低碳排放量和系统功率波动,提高系统的稳定性和经济性.
为使储能装置能够根据与频率稳定相关联的惯量补偿目标执行补偿控制,提出了"基于虚拟惯量计算的储能虚拟惯量补偿控制方法".首先依据参数的基本物理意义和储能控制模型,定义计算储能虚拟惯量(HBESS),进而建立HBESS与储能虚拟惯量控制相关参数的解析函数关系.然后提出由惯量补偿目标确定储能虚拟惯量控制参数,通过动态调节控制参数来跟踪惯量补偿目标的策略,即虚拟惯量补偿控制方法.最后通过独立微电网算例系统,验证了HBESS计算结果的精确性和控制策略的有效性.
