Setting different electricity prices for different types of loads can effectively reduce the peak power consumption in microgrids (MGs). This paper proposes a category-specific pricing strategy for demand response program in dynamic MGs that can efficiently utilize renewable energy to achieve peak shaving and valley filling via establishing a Stackelberg game model. A state characteristic clustering (SCC) based non-intrusive load monitoring (NILM) scheme is first proposed, by which both the MG market operator (MMO) and users can access the detailed power consumptions of shiftable and non-shiftable loads. MMO then specifies detailed electricity prices dynamically based on user-side demand and satisfaction feedback, while users adjust their shiftable loads in a timely manner accordingly. Through solving the game optimization problem, the uniqueness and existence of the Stackelberg equilibrium is derived. Moreover, a distributed solution algorithm is presented to seek the unique equilibrium. Finally, a real residential power dataset is used to verify the effectiveness of the proposed category-specific pricing strategy. Numerical results show that the strategy reduces the peak-valley difference significantly, mitigates the power imbalance, and improves the utility of MG participators.

With the development of distributed generation (DG) technologies, distributed energy resources (DERs) with low capacity and low inertia are highly penetrated in the islanded AC microgrid. This has highlighted the need for secondary control strategies to remedy frequency deviation and strongly limitation of the frequency synchronization rate, which are associated with the primary control. To solve this problem, an optimal condition, in terms of explicit synchronization rate formula, is derived. Then, a distributed event-triggered control strategy is proposed to synchronize the microgrid frequency to the nominal value and maximize the synchronization rate for the primary control process. To reduce the communication and computation burdens, an event-triggered mechanism that enables each agent to update its input based on discrete information from only one of its neighbors are provided. The stability of the event condition and event interval are also analyzed using Lyapunov method. Finally, the theoretical results are applied to a parallel-feeder test system consisting of fourteen DGs, which verifies the effectiveness of the proposed strategy.

Research on the optimal power allocation of large-scale distributed generator (DG) units based on user power generation to access microgrids (MGs) in a multi-agent system framework has recently become the focus of modern grid and energy concerns. In this paper, according to the Cournot oligopoly game, the Nash equilibrium point between the power generation company and power generation user of the MG operating in island mode is obtained. According to the obtained Nash equilibrium point, the optimal ratio of power generated by the power generation company and by the power generation user in the model is calculated. At the same time, to achieve the maximum benefit and stable operation of the MG, a distributed cooperative control algorithm based on consensus theory is proposed. This control algorithm can cause each DG to generate power according to the total consumption load. The optimal power generation ratio distribution based on the Nash equilibrium point eliminates the steady-state frequency deviation of each DG in the MG, thereby ensuring the user’s power quality. The simulation results show that the control algorithm can achieve the above research goals.
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When distributed generation (DG) technologies are implemented in an islanded low-voltage microgrid (LVMG), the topological architecture directly affects the frequency synchronisability. Especially in cases of high DG penetration, the synchronisability of existing traditional topological architectures for LVMGs is very limited. However, a cobweb network topology, which combines the characteristics of several traditional topological architectures, has become a novel alternative for LVMGs. In this context, a compact criterion related to the Moore-Penrose inverse of the incidence matrix for the synchronisability of an LVMG is derived. Then, based on a linear transformation and Moore-Penrose inverse theory, a comparative analysis of the synchronisability of LVMG systems with different topological architectures is presented, the results of which indicate that the synchronisability can be significantly enhanced in a cobweb network topology and that the Braess paradox can also be effectively avoided during the corresponding topological transformation. The effectiveness of the proposed synchronisation criterion is validated based on the Iceland power network, modelled as a cobweb-based LVMG with large-scale DG integration, which exhibits excellent sychronisability.

随着传统煤炭、石油等化石燃料资源的日益枯竭,微电网的发展不仅可以推动传统能源结构的转型,还在智能电网的发展中充当着重要的角色。与集中式、大容量的热力发电厂不同的是,交流微电网系统由于其分布式能源的能量密度较低、单机容量较小,故而须要大规模装机才能保证有效的输出功率,特别是在与大电网分离的孤岛模式下。然而随着分布式发电单元数量增多,整个微电网系统的动力学特性会呈现高阶多维的“维数灾”情况。故传统的对单个或多个分布式发电单元的分析与控制方法很难被推广到大规模分布式发电的相关研究中,并且在微电网的三层控制架构基础上,传统的控制方法也将不再适用。而复杂网络及多智能体理论为解决大规模电力网络系统的建模及控制提供了有利的分析工具。由于微电网中不同类型单元的动力学模型及参数不同,微电网单元之间呈现出的异构性越来越显著。本文以异构交流孤岛微电网系统为对象,围绕拓扑结构与同步稳定性分析的关系,以及分布式协同控制在微电网控制中的应用两方面开展研究。主要研究内容包括:拓扑结构对孤岛微电网的整体同步稳定性起到了至关重要的作用,而拓扑结构的变化对大规模微电网同步的影响尚缺少足够的理论研究。针对该情况,本文基于非线性系统平衡点及Moore-Penrose广义逆理论,推导出了一种新的孤岛交流微电网同步稳定性的简洁判定指标。进而从理论上分析了拓扑结构的变化对同步能力的影响。基于代数图理论及线性变化理论,比较分析了在不同的拓扑结构下的孤岛交流微电网的同步能力,并提出一种新的拓扑结构。结果表明,传统拓扑结构下的微电网同步能力在大规模分布式能源并网情况下具有较大限制,而所提出的新型拓扑结构可以显著增强微电网的同步能力也可以有效地避免在相应的拓扑变换过程中出现的Braess悖论现象。为微电网的拓扑结构设计及同步稳定性的判断方式提供了理论基础。微电网的经济性分配问题往往在其第三控制层中实现,由于时间尺度的差异,三层控制一般存在滞后性从而导致经济性降低。已有的控制策略大多考虑带有领导者节点或需要全局信息,而且未考虑微电网中的各类本地约束,故而无法反应实际的运行场景。针对孤岛交流微电网储能单元的整体经济性效率问题,本文提出了一种新的基于多智能体的无领导者分布式协同控制算法。该方法是完全分布式的,且可以协同逆变器消除稳态频率偏差并且实现系统整体经济性最优。此外,通过对充放电速率、荷电状态和充放电周期的本地约束来设计控制策略,从而使其符合实际运行场景。利用平衡点理论证明了所提出的控制器的全局渐近稳定条件。最后通过仿真实验验证了该方案在解决频率同步和经济分配问题中的有效性。当大规模分布式能源并入微电网时,系统的同步会变的更加困难,并且控制过程所需的通信和计算成本将极大增加。在孤岛模式下,微电网系统在应对负荷变化等扰动的时候频率恢复到额定值的时间以及频率的瞬态峰值偏差对系统的安全运行有着重要意义。而目前孤岛微电网的二层控制往往仅关注频率或电压的稳定状态,本文针对频率同步速率速率问题,根据非线性系统稳定性理论推导出了显式同步速率表达式,并基于线性规划理论得出了该同步速率最优条件。在此基础上,本文提出了一种分布式协同事件触发控制策略,它可以消除微电网的稳态频率偏差,且使同步速率达到最大。为了减少通信和计算负担,本文还提供了一种事件触发机制,使每个单元仅须根据其单一邻居节点的离散信息更新其控制输入,从而极大的降低了通信成本。利用李亚普诺夫方法对事件触发条件下的控制系统稳定性进行了证明,同时对事件间隔下限进行分析以避免Zeno现象。最后,仿真实验验证了所提策略的有效性。储能系统对微电网的安全稳定运行起到至关重要的作用,其荷电状态和充放电功率的合理控制对延长储能单元可延长蓄电池使用寿命。为了精确、快速及鲁棒地控制荷电状态及充放电功率,已有的控制策略大多采用有限时间的方法,然而控制系统的收敛时间往往与初始状态相关,这会导致收敛时间的估计趋于保守。针对该情况,本文提出了一种分布式协同改进有限时间控制算法。该控制算法可以协同储能单元消除系统频率的稳态偏差,并同时解决荷电状态平衡以及储能充电放电功率分配问题。利用李雅普诺夫方法和齐次近似理论证明了控制算法的稳定性,保证了在不依赖于初始条件的稳定时间内的加速收敛。在此基础上,设计了一种仅依赖离散信息且能够避免Zeno行为的事件触发通信机制,显著降低了通信负担。此外,通过施加切合实际的局部约束来实施该控制协议,进一步地提升了蓄电池的使用寿命。

This paper deduces some novel asymptotic stability criteria for different forms of multivariable fractional order systems (MFOS) whose fractional-order parameters are between 0 and 1 with time delays based on M-matrix. First, we extend the general asymptotic stability condition of ordinary systems to MFOS. Then, we investigate into the linear and nonlinear MFOS, then the asymptotic stability criterion of which derived based on M-matrix. Then, for the asymptotically stability study of the relatively complex MFOS with time delay, we also present the asymptotic stability criterion via the new method. In addition, we conduct an in-depth discussion on the stability of MFOS and integer order multivariable systems, and intuitively show the advantages of fractional-order systems through time responses. Compared with the fractional-order comparison principle, the new asymptotic stability criteria have the advantages of fewer restrictions, less conservativeness, and a wider applicability. Finally, four examples which contain MFOS covering different categories are shown.(c) 2022 Elsevier Ltd. All rights reserved.