一种面向分布式发电微电网的边缘计算架构与应用

随着边缘计算技术的快速发展,其在智能电网中的应用越来越广泛,但尚未应用于分布式发电微电网系统的运行控制中。本文首先提出了一种面向微电网的边缘计算架构,并介绍了边云协同的主要功能,其次阐述了该架构的构建方案,包括数据处理、网络通信及安全机制的实现,最后介绍了该架构在华南南海某海岛上的应用实践。     

基于ＰＩＤ控制算法的直流微网容错控制方法研究

构建直流微网容错控制对象模型，调节直流微电网的输出回路参数；以输出功率、直流微网的 参考电压、弱电网下系统惯性响应特征等为约束参量，构建直流微网容错控制目标函数，在不同电网强度下 进行直流微网容错控制的参数自整定性调节，采用无功环比例积分控制方法进行直流微网容错寻优分析， 建立模糊 ＰＩＤ控制模型，采用变结构的模糊 ＰＩＤ控制方法进行直流微网容错控制过程中的自适应加权学习 和误差反馈调节，实现直流微网容错控制改进设计。仿真结果表明，采用该方法进行直流微网控制的容错 性能较好，输出稳定性较强，具有较好的直流微网输出增益。     

A multiagent‐based microgrid operation method considering charging and discharging strategies of electric vehicles

In this paper, we propose a multiagent‐based microgrid (MG) operation method considering charging and discharging electric vehicles (EVs). The proposed system consists of five types of agents: single microgrid controller agent, several load agents, several gas turbines/engine agents, several photovoltaic generation agents, and several electric vehicle agents. In the proposed method, the load balancing can be realized by suppressing sudden fluctuations in supply and demand balance due to the synchronization of charging and discharging of EVs. From the simulation results, it can be seen that the proposed multiagent system could realize the load equalization in MG.     

Compensation of droop control using common load condition in DC microgrids to improve voltage regulation and load sharing

DC microgrid is one feasible and effective solution to integrate renewable energy resources, as well as to supply reliable electricity. The control objective of DC microgrids is to obtain system stability, low voltage regulation and equal load sharing in per unit. The droop control is an effectively method adopted to implement the control of microgrids with multiple distributed energy units. However in the application of low-voltage DC microgrids, the nominal reference mismatch and unequal cable resistances require a trade-off to be made between voltage regulation and load sharing. In this paper, a unified compensation framework is proposed using the common load condition in local controller, to compensate the voltage drop and load sharing errors. The voltage deviation is compensated with a P controller while the load sharing is compensated through a PI controller. An additional low bandwidth communication is introduced to share the output current information, and the average output current in per unit is generated to represent the common load condition. The performance of the proposed method is analyzed and compared with basic droop control and hierarchical structure method. The large signal stability is analyzed to define the margin of compensation coefficients. Simulations and experiments are carried out to verify the performance of the proposed method.     

Design and analysis of an aging‐aware energy management system for islanded grids using mixed‐integer quadratic programming

The rapid increase of renewable energy sources made coordinated control of the distributed and intermittent generation units a more demanded task. Matching demand and supply is particularly challenging in islanded microgrids. In this study, we have demonstrated a mixed‐integer quadratic programming (MIQP) method to achieve efficient use of sources within an islanded microgrid. A unique objective function involving fuel consumption of diesel generator, degradation in a lithium‐ion battery energy storage system, carbon emissions, load shifting, and curtailment of the renewable sources is constructed, and an optimal operating point is pursued using the MIQP approach. A systematic and extensive methodology for building the objective function is given in a sequential and explicit manner with an emphasis on a novel model‐based battery aging formulation. Performance of the designed system and a sensitivity analysis of resulting battery dispatch, diesel generator usage, and storage aging against a range of optimization parameters are presented by considering real‐world specifications of the Semakau Island, an island in the vicinity of Singapore.     

Advanced controller design based on gain and phase margin for microgrid containing PV/WTG/Fuel cell/Electrolyzer/BESS

Nowadays, with the increase in the amount of power generation related to renewable energy resources, the need for energy storage and management is raised. In this regard, the hydrogen energy plays a critical role in the development of renewable technologies. In view of the above, advanced controller design is presented in this paper to effectively perform load frequency control of islanded fuel cell microgrid based on the wind turbine, photovoltaic, fuel cell, electrolyzer, battery energy storage systems, and residential and commercial loads. The controller design is based on the determination of the controller parameters that the fuel cell microgrid system will provide the desired dynamic properties. In the proposed controller design, virtual gain and phase margin testers are added to provide the desired dynamic properties. The controller's stable parameter plane is determined with the help of the stability boundary locus method, taking into account time delay, gain, and phase margin. First, the accuracy of the stable parameter plane determined for the proposed controller design is demonstrated by means of time domain and eigenvalue analyzes. Finally, in order to show the performance of the advanced controller design and the success of the fuel cell as a backup generator, analysis studies have been carried out using actual data of solar and wind, and appropriate changes of load in studied microgrid.     

Enhancing stability region of time‐delayed smart power grids by non‐integer controllers

In this study, the impacts of non‐integer order controller on the stable parameter space of the microgrid (MG) frequency control system with fixed communication time delay are investigated and discussed with the help of the stability boundary locus (SBL) method. This study proposes a non‐integer order controller for the load frequency control (LFC) of the MG systems. To that end, the load frequency model of the MG is formulated and then the characteristic equations of this model are obtained. Then, with the help of this characteristic equation, the stable parameter space of the non‐integer controller is determined with regard to different time delay (τ ) and fractional integral order values (α ) using the SBL method. In order to show the accuracy of the obtained stable parameter space, time domain and generalized modified Mikhailov (GMM) criterion studies are carried out for different values of (τ ) and (α ). According to the results obtained, the areas of stable parameter space according to different α values and τ = 1.6 are calculated as 444.8860 for α = 0.4 , 342.9728 for α = 0.7 , 259.3578 for α = 1 , 216.2541 for α = 1.3 and 159.6826 for α = 1.6 . In addition, the areas of stable parameter space according to different τ values and α = 1.4 are calculated as 784.5222 for τ = 1 , 106.3219 for τ = 2 , 29.6959 for τ = 3 and 11.5946 for τ = 4 . Despite the extreme variability arising from nature of resources that make up the MG, the designed non integer order controller with the values selected within the stable parameter space stably carries out LFC control of the MG.     

Primary and secondary control of an autonomous solar microgrid based power-to-X: Renewable hydrogen conversion

The desire of achieving carbon neutrality and the decarbonization objective is the key driver for the interest in green hydrogen for power plant generation as a clean and flexible energy carrier. In fact, the use of hydrogen-based generating plants as hydrogen fuel cells in solar microgrids plays a major role in the energy transition and adds more reliability to this type of microgrid. This study presents a hierarchical control level 1 and 2 of an islanded microgrid with green hydrogen production, storage, and re-electrification. The purpose of this article is to control a stand-alone/off-grid microgrid with renewable hydrogen storage-based non-dispatchable sustainable energy solutions. An energy management strategy was implemented and a primary and secondary control was applied in order to maintain the voltage and frequency of the islanded microgrid at their steady state values.     

煤层气抽采直流微网建模与稳定性分析

针对目前煤层气抽采现场用电不合理现状,构建一种新型煤层气抽采直流微网供电系统,并对该直流微网系统稳定性及控制策略进行研究。煤层气抽采直流微网供电系统分三层结构:第一层由光伏和蓄电池组成能量供给层;第二层由双向Buck/Boost变换器构成能量传输和分配层;第三层由煤层气抽采机构成负荷层。基于此架构推导了第一、二层输出阻抗Zo(s),并建立第三层煤层气抽采机电动机输入阻抗Zin(s)与受控源K??m串联的小信号模型,在此基础上得到系统全局小信号模型。考虑到呈现负阻抗特性的煤层气抽采机电动机周期性动态交变负荷引起的系统不稳定,在能量传输和分配层分析并讨论了一种基于虚拟阻抗的直流微网稳定性控制策略,以及利用下垂控制实现负荷功率动态平衡分配的方法。进一步利用阻抗匹配原则求解多项式1/(1+Zo(s)/Zin(s))主导极点,比较采取该稳定性控制策略前后的主导极点位置并分析直流微网系统稳定性。最后基于Matlab/Simulink搭建由光伏阵列、储能单元和煤层气抽采机组成的煤层气抽采直流微网系统模型,系统仿真证明了稳定性控制策略的有效性。     

直流微网中混合储能系统的无互联通信网络功率分配策略

直流微网中通常采用混合储能系统作为缓冲环节,对分布式能源和负载引起的不同时间尺度功率波动进行补偿。为实现功率在能量密度型储能元件和功率密度型储能元件之间合理分配,提出无互联通信网络的分层控制策略。其中,底层控制以电压变化率作为虚构的信息载体,通过设置不同储能接口变换器输出电压关于功率的"灵敏度",确保超级电容在负载突变瞬间能够提供大部分功率;二次控制对底层控制产生的稳态误差进行补偿,以实现输出电压稳定,并保证超级电容稳态电流为零。在此控制框架下,各储能单元仅需本地信号即可实现自主协调运行,避免了互联通信网络所带来的经济性和可靠性问题。最后,实验结果验证所提方法的可行性和有效性。