互联电力系统模糊负荷频率控制器的优化设计

通过建立一个改进了的带修正因子的模糊（ｆｕｚｚｙ）控制表的数学表达式和一个综合性能指标，提出了一种互联电力系统分散Ｆｕｚｚｙ负荷频率控制器的自动优化设计方法。对一个两区域互联电力系统的数字仿真结果表明：所设计的分散Ｆｕｚｚｙ负荷频率控制器具有良好的控制性能。     

基于变论域模糊逻辑的互联电力系统负荷频率控制

随着风电在电力系统中的渗透率不断提高,其出力不确定性对系统频率稳定造成威胁。针对风电接入系统后的频率波动问题,提出变论域模糊PI负荷频率控制策略。为克服传统模糊控制器由于论域固定导致自适应能力有限的缺点,设计的变论域模糊PI负荷频率控制器通过变论域方法实现输入、输出论域的动态调整。为满足风电接入系统后复杂的论域调整需求,基于模糊推理设计新型变论域伸缩因子。典型两区域互联系统仿真实验表明,在不同形式的扰动下,该新型控制器较PI控制器、模糊PI控制器有更好的控制表现,能更好地处理风电出力不确定性对互联电力系统频率稳定的影响。     

基于粒子群算法的含大规模风电互联系统的负荷频率控制

以含大规模风电的互联电力系统为研究对象,以抑制风电并网时所引起的系统频率不稳定为目的,提出了基于PSO的负荷频率控制器。传统的负荷频率控制器根据区域控制偏差来调整机组的出力,使区域控制偏差ACE趋于零,从而保证全系统发出的出力和负荷功率相匹配。把风电输出当作一个负的负荷作为等效负荷,在传统的比例积分控制器中引入PSO智能控制,可以进一步提高对等效负荷的控制效果。通过在Matlab/Simulink中构建的含风电的两区域互联电力系统的仿真结果表明,无论是互联电网的频率偏差还是联络线的交换功率,控制指标更优。     

含风光水火储的多区域互联电力系统协同优化负荷频率控制

针对现代电力系统中呈现出的互联和多源的特点,首先提出了一种启发式智能优化算法辅助含风光水火储的多区域互联电力系统协同优化负荷频率控制方法,该方法以每个区域的区域控制偏差为目标函数;然后利用鲸鱼智能优化算法鲁棒性强、求解精度高及收敛快速度等优点,对各区域的PID负荷频率控制器参数进行协同优化,使得系统在各种随机扰动下,都能够维持频率稳定和长期安全运行;最后建立含风光水火储的三区域互联电力系统模型,对比不同优化整定方法下的互联电力系统频率和联络线功率偏差,测试系统在不同扰动时各区域的稳定性及所提方法的有效性。实验结果表明,所采取的多区域互联负荷频率控制器协同优化整定方法有效地改善了系统的稳定性,具有良好的鲁棒性和实用性。     

基于交替方向乘子法的分布式负荷频率控制策略

负荷频率控制(load frequency control, LFC)是维持电力系统安全稳定运行的基础。对于多区域互联电力系统,由于描述动态过程的微分方程组相当复杂,这给负荷频率控制器的设计带来了困难。在此背景下,针对多区域互联电力系统,提出基于交替方向乘子法 (alternating direction method of multiplier, ADMM) 的分布式最优负荷频率控制器设计方法,以取得良好的控制性能,同时具备较高的计算效率。首先,介绍了负荷频率控制问题的微分方程模型。之后,基于二次多项式和矩阵稀疏化构建了分布式最优LFC策略的数学模型,并采用ADMM求解。最后,以三区域互联电力系统为例对所提方法进行了验证。仿真结果表明,针对负荷扰动和时变参数,所提方法能够把各区域的频率偏差和区域间联络线上的功率偏差控制到0。     

MIMO伺服补偿分散控制原理在互联电力系统负荷频率控制中的应用

本文应用极点位移的方法,对互联电力系统的负荷频率控制(LFC)问题,设计了多输入一多输出(MIMO)伺服补偿分散控制器;并以一个两地区互联电力系统的实例,考察了这类控制器对地区系统频率f_i和联络线交换功率P_(tie,ij)对于给定值的跟踪效果。数字仿真的结果表明:由于伺服控制器对各地区系统的频率偏移Δf_i进行了二次积分,所以当电力系统中出现缓慢持续上升(或持续下降)的负荷扰动时,各地区发电量亦随之相应变化,使各地区系统频率偏移Δf_i经一定时间后到达零稳态。这类控制器同PI控制一样,易于实现,而控制效果更好。     

云模型理论在互联电力系统负荷频率控制中的应用

针对负荷频率控制系统具有不确定性问题,提出一种基于云模型理论的多区域互联电力系统负荷频率自适应PI控制方法。该方法以区域控制偏差量e作为云模型发生器的前件,PI控制器参数的整定值P和I作为云模型发生器的后件,建立适于负荷频率控制的一维云模型PI控制器。同时分别从频域和时域角度模拟不同情况下的负荷扰动,采用云模型控制器对PI控制器参数自调整,实现电力系统的负荷频率控制。仿真结果表明,在满足各种负荷扰动情况下,所提方法可有效地跟踪功率波动所引起的频率偏差,满足负荷频率控制指标,具有更强的抗干扰性和鲁棒性,其控制效果明显优于传统PI控制器。     

电力市场环境下的新型负荷频率控制方法

针对电力市场环境中的两区域互联系统,研究了负荷频率控制的非线性、参数的不确定和纯迟延特性等问题,提出了一种基于模糊径向基函数神经网络的自适应控制器,即利用径向基函数神经网络进行自学习、修正与完善模糊规则,改善其动态性能。将Matlab与Labview软件相结合进行仿真,结果表明上述方法具有较强的自适应和自学习能力,将其应用于复杂的非线性电力系统的负荷频率控制中,取得了较好的控制效果。     

考虑可控负荷的多区域电力系统分布式模型预测负荷频率控制

由于同步发电机的惯性较大,导致传统的集中式负荷频率控制模式反应不够迅速,而用户侧具有快速响应能力的可控负荷资源为系统的频率调节提供了新机遇。研究了考虑用户侧可控负荷资源主动参与系统频率调节的多区域互联电力系统分布式模型预测负荷频率控制问题。通过建立的含可控负荷的多区域互联电力系统负荷频率响应模型及自动发电控制模型,基于连续时域交替方向乘子法和分布式模型预测控制方法,提出了一种用户侧可控负荷资源主动参与的多区域互联电力系统分布式模型预测最优负荷频率控制模型。基于修改的IEEE39节点三区域互联电力系统进行仿真验证,结果表明所提考虑可控负荷的分布式模型预测控制策略可显著减少系统恢复至稳态所需的时间。分布式控制策略的控制自由度更高,增强了系统的可控性。     

新能源互联电力系统双积分反馈PID负荷频率控制

针对光伏新能源电力系统的调频困难问题,提出一种基于改进天牛须搜索算法的粒子群优化算法,实现对光、火、储两区域互联电力系统的负荷频率控制。首先,将储能电池引入混合电力系统中,建立光伏、火电及储能电池的两区域互联电力系统的负荷频率控制模型,并设计出含滤波系数的双积分反馈PID控制器;然后,引入方向改变因子改进天牛须搜索算法,提出一种基于改进天牛须搜索算法的粒子群优化算法,用于优化含滤波系数的双积分反馈PID控制器参数。最后,通过数值仿真,仿真结果表明,本文所提的控制策略在对于频率偏差、区域控制偏差和联络线功率偏差等方面的控制效果、抗扰动能力,优于粒子群优化算法、天牛须搜索算法和含滤波系数的双积分PID控制器。     

Two-level optimal load–frequency control for multi-area power systems

In large-scale power systems, classical centralized control approaches may fail due to geographically distribution of information and decentralized controllers result in sub-optimal solution for load–frequency control (LFC) problems. In this paper, a two-level structure is presented to obtain optimal solution for LFC problems and also reduce the computational complexity of centralized controllers. In this approach, an interconnected multi-area power system is decomposed into several sub-systems (areas) at the first-level. Then an optimization problem in each area is solved separately, with respect to its local information and interaction signals coming from other areas. At the second-level, by updating the interaction signals and using an iterative procedure, the local controllers will converge to the overall optimal solution. By parallel solving of areas, the computational time of the algorithm is reduced in contrast to centralized controllers. This approach is applicable to any interconnected large-scale power system. However, for simulation purposes, a three-are power system is presented to show advantages and optimality of the proposed algorithm.     

Fractional-order Proportional-integral-derivative-based Automatic Generation Control in Deregulated Power Systems

Abstract—In this article, implementation of a fractional-order proportional-integral-derivative controller is proposed as supplementary automatic generation control of interconnected multi-area deregulated power systems that operates under the effects of bilateral contracts on the dynamics. The tuning of the fractional-order proportional-integral-derivative controller parameters is formulated as an optimization problem and solved by employing a genetic algorithm. The traditional automatic generation control loop incorporated with the concept of the distribution company participation matrix and fractional-order proportional-integral-derivative supplementary controller is simulated for different operating cases; a comparison among the conventional integral controller, hybrid fuzzy proportional-integral controller, genetic algorithm-tuned proportional-integral controller, and genetic algorithm-tuned proportional-integral-derivative controllers is presented. The simulation results show that the system employing a genetic algorithm-tuned fractional-order proportional-integral-derivative controller has better performance than the integer-order hybrid fuzzy proportional-integral, genetic algorithm-tuned proportional-integral, and genetic algorithm-tuned proportional-integral-derivative controllers in terms of settling time and overshoot.     

Robust decentralized load frequency control of interconnected power system with Generation Rate Constraint using Type-2 fuzzy approach

The Load Frequency Control (LFC) problem has been a major subject in electrical power system design/operation. LFC is becoming more significant recently with increasing size, changing structure and complexity in interconnected power systems. In practice LFC systems use simple Proportional Integral (PI) controllers. As the PI control parameters are usually tuned, based on classical approaches. Moreover, they have fixed gains; hence are incapable of obtaining good dynamic performance for a wide range of operating conditions and various load changes, in multi-area power system. Literature shows that fuzzy logic controller, one of the most useful approaches, for utilizing expert knowledge, is adaptive in nature and is applied successfully for power system stabilization control. This paper proposes a Type-2 (T2) fuzzy approach for load frequency control of two-area interconnected reheat thermal power system with the consideration of Generation Rate Constraint (GRC). The performance of the Type-2 (T2) controller is compared with conventional controller and Type-1 (T1) fuzzy controller with regard to Generation Rate Constraint (GRC). The system parametric uncertainties are verified by changing parameters by 40% simultaneously from their typical values.     

Optimal Decentralized Load Frequency Control

The paper presents a novel methodology for feasibility analysis and design of optimal decentralized load frequency control for multi-area interconnected electric power systems. Feasibility of the proposed decentralized control scheme is determined with a fixed mode evaluation algorithm based on eigenvalue dynamics. The eigenvalue sensitivity expressions are also used to determine decentralized feedback gains that will result in system transient performance similar to the one obtained with a centralized optimal control law. The methodology is illustrated with a two-area power system example.     

Enhancement of interconnected power system stability using a control strategy involving static phase shifters

The static phase shifting transformer is one of the potential options of the recently proposed FACTS (flexible AC transmission systems). Promising results have been obtained for enhancing the small-disturbance and the transient stability of interconnected power systems.

In this paper, the important concept of involving in the same control strategy both generating units and static phase shifters has been considered. A systematic procedure for designing co-ordinated and decentralized controllers of these components is provided to assure a satisfactory dynamic performance of an interconnected power system under both small and large perturbations. The approach uses optimal control theory as a basis for the co-ordination of static phase shifter and governor controllers. A suboptimal decentralized control scheme is derived from the designed optimal controller by using a ‘minimum norm’ nearness criterion. The resulting feedback control signals for each generating unit and for each phase shifter is expressed in terms of measurable and local variables only.

Test results show the effectiveness of the proposed control strategy and the usefulness of control actions on static phase shifters.     

考虑电动汽车集群的互联电网负荷频率分散预测控制

随着大量电动汽车接入互联电网,其移动的充电模式会给电网带来一定的冲击,反过来,电动汽车作为一种移动式储能单元可参与互联电网调频,但目前的研究都是集中式或分散式的V2G控制上.在电动汽车储能电池动态模型的基础上,构建含电动汽车集群的多区域互联电网负荷频率控制模型,基于广域监测系统,结合模型预测控制实现了多区域电网负荷频率广域分散预测控制.在MATLAB/Simulink中搭建三区域互联电网模型,并进行仿真分析.算例结果表明,电动汽车作为移动式储能单元参与互联电网调频,可以在短时间内平抑电网频率波动;而文中提出的广域分散预测控制方法较经典的PI控制方法,能将三区域电网的频率偏差限制在更小的范围内波动,又能较快地恢复至稳态值.     

Delay-independent decentralized stabilizer design for large interconnected power systems based on WAMS

Recent stabilizer design using wide-area measurement systems (WAMS) signals has been suggested to enhance the dynamic performance of large interconnected power systems. However, there is an unavoidable delay involved before these signals are received at the stabilizer site. Long time-delay may be detrimental to system stability and may degrade system performance. Therefore, the delay-independent robust control problem of large interconnected power systems based on WAMS is studied via H_∞ fuzzy control method. First, a set of equivalent Takagi–Sugeno (T–S) fuzzy model is employed to represent the large interconnected power systems. A wide-area state feedback decentralized control scheme is developed to stabilize the T–S fuzzy systems without any wide-area signals delay information such that the H_∞ performance is achieved. The H_∞ fuzzy robust control design problem is parameterized in terms of a linear matrix inequality (LMI) problem, and the LMI problem can be solved very efficiently using the convex optimization techniques. Finally, the performance of the robust control is studied using a fourteen-machine interconnected power system example.     

考虑风电不确定性的多区电力系统分散式随机调度方法

在考虑风电出力不确定性的基础上研究了多区域电网分散式优化问题。首先,对区域边界共享节点进行复制以实现互联电网的解耦,然后,基于场景法对风电随机性进行建模,构建区域电网两阶段随机优化模型,最后,采用同步型交替方向乘子法(Synchronous Alternating Direction Method of Multipliers,SADMM)交替求解全网分散优化问题和区域两阶段随机优化问题。采用修改的新英格兰39节点系统构建3区域互联电网进行仿真测试,验证了所提模型能够有效应对风电的随机不确定性,并实现各区域电网调度的分散自治。     

Decentralized bounded input bounded output stabilization of perturbed interconnected time-delay power systems with energy storages

This paper presents a new decentralized bounded input bounded output (BIBO) stabilization problem for a class of interconnected time-delay systems and its application to power systems with energy storages. We first provide conditions for the derivation of an ellipsoid that bounds a given linear functions of the state vector. Then, a design procedure is proposed to synthesize decentralized static output feedback controllers. The designed controllers guarantee that a given linear functions of the state vector, starting from any initial condition, converges exponentially to its prescribed zones. To deal with the time-delay issue, we use an improved weighted integral inequality recently reported in the literature to derive less conservative exponential stability conditions. Then, our presented control approach is applied to an interconnected power system integrated energy storages with multiple time delays. We synthesis decentralized static output feedback load frequency controllers to guarantee that the system frequency and interchanged power converge to their prescribed zones exponentially from any initial conditions. The controller’s construction is simpler and easier for implementation due to only the local output measurements are required. In order to systematically obtain the controller gains, an effective procedure using linear matrix inequality based stabilisation criteria, which can be solved by various computation tools, is provided. Finally, the effectiveness of the proposed control scheme is verified by comprehensive simulations.