基于动态下垂控制的温控负荷一次调频控制策略

利用温控负荷(thermostatically controlled load,TCL)作为调频资源参与电网调频是应对高比例可再生能源发电并网导致电力系统维持频率稳定能力下降的有效手段。文中提出一种基于动态下垂控制的TCL一次调频控制策略,考虑聚合商TCL平均温度状态(state of temperature,SOT)、调频容量和系统频率变化率,构建动态下垂控制模型,实时调整下垂控制系数,改变TCL聚合商调频参与度。当向上调频时,锁定关状态TCL;当向下调频时,锁定开状态TCL,确保频率快速恢复至额定值附近。同时,为确保用户的舒适度,利用TCL的SOT优先级排序列表派遣法,确定TCL参与调频顺序。在Matlab/Simulink平台上进行仿真分析,仿真结果验证了文中所提策略在确保用户舒适度、改善频率质量等方面的有效性。

计及离散控制偏差的典型温控负荷态势感知及调控策略

针对温控负荷离散化控制模式导致的临界温度效应累计偏差,提出一种计及离散控制偏差的温控负荷集群调控策略。通过引入修正因子改进负荷可消纳能力评估模型,并以热水器群为主要研究对象,将用户用水行为引入统一负荷模型,提升模型与实际环境的拟合性;提出负荷态势计算指标,基于其实时状态,以温度裕度、时间裕度和容量裕度为子指标进行综合,实现对于负荷调控能力的评价。仿真结果证明：综合考虑用户用能需求情况下,引入修正因子和用户行为分析的感知调控策略,可实现精准负荷调控,降低负荷资源储备需求。

基于反推控制的聚合温控负荷与发电机励磁协调控制

利用具有储能特性的温控负荷与发电机励磁进行协调控制,可实现电力系统的功角、频率和电压的多指标调控。首先,采用双线性聚合温控负荷模型和发电机励磁模型,推导建立了二者联合的系统数学模型。然后,基于反推控制原理,提出了聚合温控负荷与发电机励磁的协调控制策略,并从理论上证明了控制器的稳定性。针对控制器设计中的微分'计算爆炸'问题,利用双曲正切的非线性微分跟踪器设计了励磁电压参考量的微分估计算法,降低了参考量微分计算的工作量。最后,通过算例对控制算法进行了仿真验证。结果表明,在协调控制器的作用下,系统功角、频率和电压等多个被控量均可快速地追踪上各自的参考值。对比传统电力系统稳定器励磁控制,温控负荷参与调控能有效改善系统各状态量的动态响应,提高系统稳定性。

温控负荷提供电力系统辅助服务的关键技术综述

温控负荷能够向电力系统提供多种辅助服务,在提高系统稳定运行能力的同时减少碳排放量,因而已成为国内外研究的关注热点。文中结合国内外研究成果,从参与机制、聚合模型、响应特性、终端层控制方法及架构、电网层控制策略5个方面对温控负荷提供电力系统辅助服务的关键技术进行综述。温控负荷的响应特性和终端层控制方法是构建和落实温控负荷多种控制策略的基础。文中以响应潜力、响应速度以及调控时间尺度为视角对温控负荷的响应特性进行分析,着重从控制与优化的角度对电网调度中的温控负荷控制策略进行分类与介绍。最后,结合“双碳”发展目标对温控负荷进一步的研究方向进行了展望。

计及反弹效应的温控负荷有序削峰策略

近年来,高峰用电负荷逐年增长,峰谷差进一步拉大,给电网运行带来了很大的压力。因此,以电热水器和空调两种温控负荷作为受控对象,考虑负荷调控过程中出现的反弹效应,基于全时段和分时段两类控制策略,提出了一种负荷调度的线性规划数学模型,从而最大程度上实现负荷峰值的有序削减。通过对南京市夏季典型日负荷的调控,分析了不同条件下的峰值削减情况,验证了此模型的有效性。

电动汽车与温控负荷虚拟电厂协同优化控制策略

电动汽车和温控负荷以其快速的功率调节能力,成为参与需求侧响应的灵活资源,能够为电网提供调峰调频等辅助服务。首先,分析了电动汽车和温控负荷虚拟电厂建模所需数据,建立了单体入网可控负荷的精细化模型。在此基础上分析上述两种可控负荷在入网和用能过程中的响应特性,并结合两种可控负荷的接入状态,提出了电动汽车和温控负荷虚拟电厂模型来分析虚拟电厂响应能力的时间分布特性。然后,设计了两类虚拟电厂协同优化控制的实现框架,以经济调控成本最低为目标构建了协同优化控制模型,提出考虑温控负荷用能舒适度和电动汽车接入状态变化的序列排序控制策略。最后,通过典型算例验证了协同优化控制策略的有效性。

适应清洁能源消纳的配电网直接负荷控制模型与仿真

研究配电网中直接负荷控制技术及其改变集中式热力学可控负荷的温度设定点来控制负荷功率的方法。建立以双耦合偏微分方程组为基础的热力学可控负荷传输动态模型,通过有限差分近似为面向控制的有限维状态空间模型。提出适应出力不确定性的清洁能源滑模变结构功率跟踪控制策略,利用李亚普诺夫稳定理论验证其收敛性。在小型配电网中,对1 000个制冷空调负荷进行仿真,功率跟踪误差分析结果表明所提方法能有效跟踪风电功率消纳目标,温度设定点控制分析结果表明所提方法的用户可接受百分比达到90%以上。该方法可为需求侧响应负荷在清洁能源消纳的应用提供新的技术途径。

电力需求侧温控负荷集群的聚合辅助服务

在智能电网用电负荷中,温控负荷作为主要的可调节负荷占有较高的比例,合理的引导和控制它们有序用电,对于电网的稳定运行与智能调节起着关键性的作用。文章主要探讨了温控负荷的个体建模和聚合近似建模,以及聚合负荷的辅助服务供给模式。给出温控负荷的个体建模和聚合建模方法及常用的理论研究与系统仿真模型,并对此类温控负荷的可应用场景给出了可实现框架结构,分别为基于频率响应调节的分散式温控负荷调频服务、基于负荷削减的集中式二次调频负荷调度服务、基于温度设定点控制的负荷跟随辅助服务。研究结果表明:聚合温控负荷集群可以作为需求侧的可控负荷资源,为电力系统稳定运行提供可观的备用容量。

计及开关寿命损耗的温控负荷分布式控制策略

温控负荷(TCLs)作为一种重要的需求侧资源,在平抑可再生能源波动方面具有巨大的潜力。然而,传统TCLs控制策略通常不考虑控制成本以及TCLs开关频率过高导致的寿命损耗。为降低TCLs的开关寿命损耗,文中提出了一种计及开关寿命损耗的TCLs分布式协同控制策略。首先引入矫正切换时间的概念,建立计及TCLs热力学特性和开关寿命损耗的控制成本模型;然后引入多智能体一致性控制,采用分布协同式控制方法实现TCLs控制成本最优。算例结果表明,所提控制策略能够反映TCLs热力学特性,在实现控制目标的前提下大大降低开关寿命损耗。

Load curve smoothing strategy based on unified state model of different demand side resources

Renewable energy based distributed generation(DG) has the potential to reach high penetration levels in the residential region. However, its integration at the demand side will cause rapid power fluctuations of the tieline in the residential region. The traditional generators are generally difficult to manage rapid power fluctuations due to their insufficient efficiency requirements and low responding speed. With an effective control strategy, the demand side resources(DSRs) including DGs, electric vehicles and thermostatically-controlled loads at thedemand side, are able to serve as the energy storage system to smooth the load fluctuations. However, it is a challenge to properly model different types of DSRs. To solve this problem, a unified state model is first developed to describe the characteristics of different DSRs. Then a load curve smoothing strategy is proposed to offset the load fluctuations of the tie-line of the residential region, where a control matrix deduced from the unified state model is introduced to manage the power outputs of different DSRs,considering the response order and the comfort levels.Finally, a residential region with households is used to validate the load curve smoothing strategy based on the unified state model, and the results show that the power fluctuation rate of the tie-line is significantly decreased.Meanwhile, comparative study results are shown to demonstrate the advantages of the unified state model based load curve smoothing strategy.

Day-ahead scheduling of large numbers of thermostatically controlled loads based on equivalent energy storage model

Due to their heat/cool storage characteristics, thermostatically controlled loads(TCLs) play an important role in demand response programmers. However, the modeling of the heat/cool storage characteristic of large numbers of TCLs is not simple. In this paper, the heat exchange power is adopted to calculate the power instead of the average power, and the relationship between the heat exchange power and energy storage is considered to develop an equivalent storage model, based on which the time-varying power constraints and the energy storage constraints are developed to establish the overall day-ahead schedulingmodel. Finally, the proposed scheduling method is verified using the simulation results of a six-bus system.

Unified Control Strategy of Heterogeneous Thermostatically Controlled Loads with Market-based Mechanism

This paper studies the coordination of heterogeneous thermostatically controlled loads(TCLs)to provide the real-time ancillary services.A market-based control framework is adopted for its advantages.The first advantage is that the demand curve-oriented approach makes it possible to form a unified control scheme for heterogeneous loads without identifying their different characteristics.The second one is that the broadcast price signal helps simplify the downlink control and reduce the implementation cost.Then,the separate demand curve construction strategies based on a virtual price for different types of TCLs are presented.The flexibility of each TCL is reflected through the curve,and its practical constraints,i.e.,comfort requirements of users and operation constraints of devices,are satisfied explicitly.To ensure the control fairness and full utilization for the regulation ability of TCL cluster,a comfort-levelequality principle is applied in demand curve construction.Simulations are carried out to verify the effectiveness of the proposed method in providing frequency regulation services,for which a regulation capacity estimation method is developed.Finally,a series of case studies are conducted considering the practical situations,e.g.,model errors,imperfect communication and sudden load change after the end of services.

Review of modeling and control strategy of thermostatically controlled loads for virtual energy storage system

The increasing penetration of renewable energy sources (RESs) brings more power generation fluctuations into power systems, which puts forward higher requirement on the regulation capacities for maintaining the power balance between supply and demand. In addition to traditional generators for providing regulation capacities, the progressed information and communication technologies enable an alternative method by controlling flexible loads, especially thermostatically controlled loads (TCLs) for regulation services. This paper investigates the modeling and control strategies of aggregated TCLs as the virtual energy storage system (VESS) for demand response. First, TCLs are modeled as VESSs and compared with the traditional energy storage system (ESS) to analyze their characteristic differences. Then, the control strategies of VESS are investigated in microgrid and main grid aspects, respectively. It shows that VESS control strategies can play important roles in frequency regulation and voltage regulation for power systems’ stability. Finally, future research directions of VESS are prospected, including the schedulable potential evaluation, modeling of TCLs, hierarchical control strategies of VESS considering ESSs and RESs and reliability and fast response in frequency control for VESS.