考虑状态受限和一致性的微电网二次控制

为解决交流微电网下垂控制产生的偏差问题, 本文采用二次控制对分布式电源输出电压和频率进行调节. 将微电网看成分布式多智能体系统, 智能体间通过稀疏网络进行通信, 运用多智能体一致性协议, 本文提出一种基 于障碍Lyapunov函数和自适应模糊系统的二次电压和频率控制器. 采用障碍Lyapunov函数设计控制器, 不但能保 持系统的稳定性, 还可使输出的电压和频率限制在预设的范围内. 采用自适应模糊系统可对系统中的一些参变量的 变化进行估计, 提高了控制器的鲁棒性. 本文给出了严格的稳定性证明. 通过对负载变化, 以及拓扑结构改变等的 仿真测试, 验证了所提方案的有效性.     

含多能微网群的区域电热综合能源系统分层自治优化调度

分布式能源与负荷聚合形成多能微网群连接至区域供热系统和上级配电网,构成区域电热综合能源系统.为保护多利益主体隐私并满足其利益诉求,提出了基于分布自治、集中协调设计架构的区域电热综合能源系统分层优化调度方法.在上层,计及多能流异质动态特性,提出了区域电热综合能源系统的动态经济调度模型;在下层,考虑用户柔性热需求和分布式光伏不确定性,建立了多能微网自治能量管理的机会约束模型.基于目标级联分析法将上下层解耦,层间仅需交换边界电功率和热功率,通过微网并行计算与层间迭代求解获得全局最优策略.算例结果证明,该方法能够在保证收敛性的前提下,为含多能微网群的区域电热综合能源系统提供高精度的多能互补优化调度结果.此外,对缩放因子进行灵敏度分析,讨论了算法误差来源并说明了算法最优性.     

考虑扰动影响的微电网分布式自适应控制策略

通信网络、可编程控制器的引入在为微电网控制策略设计提供便利的同时,也增加了系统遭受多种类型扰动的可能性.针对控制通道中存在的未知扰动,定量分析了扰动对基于一致性的常规微电网次级控制策略产生的不利影响.进一步,提出了一种基于自适应积分滑模的微电网次级控制策略,分析了所提分布式控制策略在扰动下的动态性能,理论证明了该策略对...     

Intertied ac–ac microgrids with autonomous power import and export

Intertied ac–ac microgrids offer many potential benefits like flexible frequency and voltage selection, reserve sharing and enhanced supply reliability. Operating them is however challenging due to their larger size and presence of more power converters with different responsibilities. These complexities can further be amplified when reliance on fast communication links is not permitted. To address these concerns, a new autonomous droop scheme is proposed here for managing intertied microgrids in either the islanded or grid-connected mode. The scheme prioritizes various power generation/transfer responsibilities among power converters found in the intertied microgrids. The objective is to smoothly maximize the overall power handling capability of the intertied microgrids without relying on fast communication links. The proposed scheme has been tested experimentally in the laboratory.     

A new linear model for active loads in islanded inverter-based microgrids

Active rectifier loads have major effects on the stability of microgrids, therefore the modeling and analysis of such loads become more popular, recently. In this paper, a new linear state-space model for inverter-based microgrids (IBMGs) as well as active loads is proposed and then the model is corrected using a time-step simulation. The proposed simulation drives the eigenvalues and transient response of such loads and systems directly and quickly which makes the stability analysis of active loads simple. Using these advantages, the load-flow analysis and, moreover, the linearization of equations around an operating point to study small-signal stability are no longer needed. The proposed method can also study large-signal stability analysis as simple and fast as the small one and the execution time of the simulation is much smaller than that of other simulations. The analysis and stability assessment of active loads in IBMGs are easy and fast using the proposed model due to linearity. The validation and comparison of different case studies show the performance of the proposed method.     

Distributed Cooperative Control of Battery Energy Storage Systems in DC Microgrids

The control of battery energy storage systems(BESSs)plays an important role in the management of microgrids.In this paper,the problem of balancing the state-ofcharge(SoC)of the networked battery units in a BESS while meeting the total charging/discharging power requirement is formulated and solved as a distributed control problem.Conditions on the communication topology among the battery units are established under which a control law is designed for each battery unit to solve the control problem based on distributed average reference power estimators and distributed average unit state estimators.Two types of estimators are proposed.One achieves asymptotic estimation and the other achieves finite time estimation.We show that,under the proposed control laws,SoC balancing of all battery units is achieved and the total charging/discharging power of the BESS tracks the desired power.A simulation example is shown to verify the theoretical results.     

Distributed Periodic Event-Triggered Optimal Control of DC Microgrids Based on Virtual Incremental Cost

This article presents a distributed periodic eventtriggered(PET)optimal control scheme to achieve generation cost minimization and average bus voltage regulation in DC microgrids.In order to accommodate the generation constraints of the distributed generators(DGs),a virtual incremental cost is firstly designed,based on which an optimality condition is derived to facilitate the control design.To meet the discrete-time(DT)nature of modern control systems,the optimal controller is directly developed in the DT domain.Afterward,to reduce the communication requirement among the controllers,a distributed event-triggered mechanism is introduced for the DT optimal controller.The event-triggered condition is detected periodically and therefore naturally avoids the Zeno phenomenon.The closed-loop system stability is proved by the Lyapunov synthesis for switched systems.The generation cost minimization and average bus voltage regulation are obtained at the equilibrium point.Finally,switch-level microgrid simulations validate the performance of the proposed optimal controller.     

Recent trends in power management strategies for optimal operation of distributed energy resources in microgrids: A comprehensive review

The current era in sustainable development is focused on the rapid integration of renewable energy sources driven by a wide range of socio-economic objectives. Due to the inherent property of time-varying weather conditions, the intermittent sources, that is, Solar PV and Wind Energy, are considered as variable energy resources. The uncertainty and variability problem of these sources has brought many complications to distributed network operators to operate and control the complex or multi-microgrids with limited fast-ramping resources in order to maintain the power system flexibility. It led many researchers to find an alternative strategy since the conventional approaches are no longer adequate to handle the economic implications of operational decision making. At first, the brief review of various deterministic and probabilistic approaches, stochastic programming and robust optimisation strategies to address the uncertainty of variable energy resources are discussed. Furthermore, in the energy management point of view, the optimal scheduling problem of distributed sources of the microgrid is considered, and a brief review of optimisation models, advanced control strategies and demand response strategies to maximise economic benefits of microgrids are also elaborately presented. Finally, the multiagent-based distributed and decentralised control strategies for seamless integration of distributed generator units are reviewed under various configurations of the power grid along with communication network topologies.     

交直流混合微网中双向接口变换器控制综述

在交直流混合微网中,双向AC/DC接口变换器连接交直流母线实现子网之间的能量双向流动,其控制策略直接影响交直流混合微网的稳定运行。根据微电网的运行模式,接口变换器的控制可以分为并网控制和孤岛控制两大类。首先对交直流混合微网的结构进行了分析和讨论,随后分别介绍了并网模式和孤岛模式下单台接口变换器以及多台并联接口变换器的控制策略。最后对当前主要的控制方法进行了总结,并对未来双向接口变换器的研究方向进行了展望。     

Adaptive Decentralized Output-Constrained Control of Single-Bus DC Microgrids

A single-bus DC microgrid can represent a wide range of applications. Control objectives of such systems include high-performance bus voltage regulation and proper load sharing among multiple distributed generators (DGs) under various operating conditions. This paper presents a novel decentralized control algorithm that can guarantee both the transient voltage control performance and realize the predefined load sharing percentages. First, the output-constrained control problem is transformed into an equivalent unconstrained one. Second, a two-step backstepping control algorithm is designed based on the transformed model for bus-voltage regulation. Since the overall control effort can be split proportionally and calculated with locally-measurable signals, decentralized load sharing can be realized. The control design requires neither accurate parameters of the output filters nor load measurement. The stability of the transformed systems under the proposed control algorithm can indirectly guarantee the transient bus voltage performance of the original system. Additionally, the high-performance control design is robust, flexible, and reliable. Switch-level simulations under both normal and fault operating conditions demonstrate the effectiveness of the proposed algorithm.