Hybrid Control Strategy for Matrix Converter Fed Wind Energy Conversion System

In this paper, a hybrid control strategy for a matrix converter fed wind energy conversion system is presented. Since the wind speed may vary, output parameters like power, frequency and voltage may fluctuate. Hence it is necessary to design a system that regulates output parameters, such as voltage and frequency, and thereby provides a constant voltage and frequency output from the wind energy conversion system. Matrix converter is used in the proposed solution as the main power conditioner as a more efficient alternative when compared to traditional back-back converter structure. To control the output voltage, a vector modulation based refined control structure is used. A power tracker is included to maximize the mechanical output power of the turbine. Over current protection and clamp circuit input protection have been introduced to protect the system from over current. It reduces the spikes generated at the output of the converter. The designed system is capable of supplying an output voltage of constant frequency and amplitude within the expected ranges of input during the operation. The matrix converter control using direct modulation method, modified Venturini modulation method and vector modulation method was simulated, the results were compared and it was inferred that vector modulation method was superior to the other two methods. With the proposed technique, voltage transfer ratio and harmonic profile have been improved compared to the other two modulation techniques. The behaviour of the system is corroborated by MATLAB Simulink, and hardware is realized using an FPGA controller. Experimental results are found to be matching with the simulation results.

Maximum Power Extraction Control Algorithm for Hybrid Renewable Energy System

In this research,a modified fractional order proportional integral derivate(FOPID)control method is proposed for the photovoltaic(PV)and thermoelectric generator(TEG)combined hybrid renewable energy system.The faster tracking and steady-state output are aimed at the suggested maximum power point tracking(MPPT)control technique.The derivative order number(μ)value in the improved FOPID(also known as PIλDμ)control structure will be dynamically updated utilizing the value of change in PV array voltage output.During the transient,the value ofμis changeable;it’s one at the start and after reaching the maximum power point(MPP),allowing for strong tracking characteristics.TEG will use the freely available waste thermal energy created surrounding the PVarray for additional power generation,increasing the system’s energy conversion efficiency.A high-gain DC-DC converter circuit is included in the system to maintain a high amplitude DC input voltage to the inverter circuit.The proposed approach’s performance was investigated using an extensive MATLAB software simulation and validated by comparing findings with the perturbation and observation(P&O)type MPPT control method.The study results demonstrate that the FOPID controller-based MPPT control outperforms the P&O method in harvesting the maximum power achievable from the PV-TEG hybrid source.There is also a better control action and a faster response.

A Novel Polymorphic Topology with Hybrid Control Strategy Based LLC Resonant Converter for Ultra-Wide Input Voltage Range Applications

To realize effective utilization of renewable energy sources,a novel polymorphic topology with hybrid control strategy based LLC resonant converter was analyzed and designed in this paper.By combining the merits of a full bridge LLC resonant converter,three-level half bridge LLC resonant converter,and variable frequency control mode,the converter realizes an intelligent estimation of input voltage by automatically changing its internal cir-cuit topology.Under this control strategy,different input voltages determine different operation modes.This is achieved in full bridge LLC mode when the input voltage is low.If the input voltage rises to a certain level,it operates in three-level half bridge LLC mode.These switches are digital and entirely carried out by the DSP(Digi-tal Signal Processor),which means that an auxiliary circuit is unnecessary,where a simple strategy of software modification can be utilized.Experimental results of a 500W prototype with 100V~600V input voltage and full load efficiency of up to 92%are developed to verify feasibility and practicability.This type of converter is suitable for applications with an ultra-wide input voltage range,such as wind turbines,photovoltaic generators,bioenergy,and other renewable energy sources.

Optimization of an annular wave energy converter in a wind-wave hybrid system

A hybrid system of a spar-type floating offshore wind turbine and a heaving annular wave energy converter(WEC)provides a promising solution for collocated ocean renewable energy exploitation.The performance of the hybrid system depends on the dimensions of the WEC.Here an optimization method is proposed to determine the outer radius and the draft of the WEC under the wave condition in a randomly chosen operational site.First,three candidate models are selected based on three operational conditions of energy harvest:(1)The natural frequency of the system is matched with the peak wave frequency in the target site(referred to as synchronized mode),where the wind turbine and the WEC nearly heave together in a near-resonance condition,(2)The natural frequency of the WEC is matched with the peak wave frequency(ring mode),(3)The maximum wave power is harnessed under the peak wave frequency(target mode).Then the candidate modes are evaluated to obtain an optimum.Results show that the extracted wave power under the above operational conditions has an upper bound that can hardly be surpassed by enlarging the dimensions of the WEC only.The optimal annual wave energy production is achieved in the synchronized mode because of the superior performance of WEC over a wide bandwidth of effective energy conversion.

基于混合储能的交直流混联微电网功率分级协调控制策略

针对交直流混联微电网孤岛运行时,仅靠互联变流器协调网间功率无法有效缓解系统频率与电压波动,且单一蓄电池储能难以适用多场景功率需求的问题,提出利用超级电容和蓄电池混合储能的交直流混联微电网功率协调控制策略。将混合储能作为储能子网连接在直流母线上,优先采用超级电容平抑交直流子网内功率波动,提出以储能荷电状态来划分五种工作模式的改进混合储能控制策略。兼顾超级电容快速响应特性和减少互联变流器的频繁起动,根据直流子网电压和交流子网频率波动程度,提出功率自治和功率互济工况的两级分层协调控制策略。通过设计混合储能处于不同工作模式的网间功率互济场景,仿真证明了所提混合储能和互联变流器协调控制策略能够平抑各子网负荷功率波动。

基于改进秃鹰优化算法的海上混合光伏波浪能转换器阵列优化

近年来,海上能源发电技术备受瞩目,一种新兴趋势是将波浪能转换器(wave energy converter,WEC)与海上光伏(offshore floating photovoltaic,OFPV)相结合,形成混合光伏-波浪能转换器系统(hybrid PV-wave energy converter,HPV-WEC)。HPV-WEC具有提高海上空间利用率,降低成本以及实现功率稳定输出等优势。为了充分利用HPV-WEC系统之间的协同效应,在不增加新设备的情况下提高能源产量,提出了一种基于改进秃鹰优化算法(improved bald eagle search algorithm,IBES)的HPV-WEC阵列布局优化策略。IBES结合了莱维飞行策略和模拟退火(simulated annealing,SA)机制,以平衡局部开发和全局探索之间的关系。为了评估IBES在优化HPV-WEC阵列方面的有效性,进行了5个浮标和8个浮标规模的阵列优化,并将IBES与其他5种算法进行了比较。实验结果表明,IBES表现出实现最大总功率输出并具有显著的收敛特性。

基于神经网络的微电网交错并联变换器的改进自抗扰控制

针对混合储能微电网在负载突变、扰动加入等多种复杂工况下引起的用电端降压接口的电压质量降低的问题,文章设计了一种以改进线性自抗扰为主要控制器,以BP神经网络为辅助参数优化算法的闭环控制策略。首先,根据六路交错并联变换器的电路拓扑建立时域下的数学模型,并对系统总扰动进行重构,将总扰动分解为模型未知扰动和外界扰动,分别利用观测器进行估计,形成了改进线性自抗扰控制,提高系统的扰动观测能力和观测精度;其次,为使系统获得控制参数的实时优化能力,引入BP神经网络,对控制器参数进行实时整定;最后,搭建了混合微电网六路交错并联变换器的数字仿真模型和半实物仿真模型进行验证,并与PI,LADRC进行了比较。结果显示,所提控制策略不仅具备优异的输出电压质量,而且使系统获得了更好的稳定性与鲁棒性。

基于混合粒子群算法的波浪能发电集群优化方法

对波浪能发电集群的优化控制有助于波浪能的有效利用,为此文章提出了基于混合粒子群算法的波浪能发电集群优化方法。以直驱式发电装置为研究对象,探讨其构成发电集群短期尺度下稳定状态的数学模型,由简至繁依次考虑波浪动态压力、装置间辐射影响和遮挡效应,以便更准确地模拟一定密集度的波浪能发电装置部署下的实际效果。以集群功率最大化为优化目标,根据装置运动和海域能量约束,提出混合粒子群算法求解集群的最优参数,在传统算法基础上设定自适应惯性权重并加入交叉和变异操作,以应对复杂集群方程解空间的多峰性问题。算例结果验证了所述集群优化方法的有效性,求解质量良好;同时表明波浪能发电集群规模越大,装置之间的辐射影响越复杂,遮挡效应越明显。

光储直流微电网系统协调控制策略研究

为了更好地控制、管理和使用随机性较大的分布式可再生能源和需求波动较大的负载,文章对光储直流微电网系统内不同的变换器提出不同控制策略,通过不同控制策略控制变换器协调运行来保证系统的稳定运行,同时利用基于超级电容和蓄电池的互补特性设计了级联的拓扑结构组成混合储能系统,使系统稳定性进一步提高;并将系统分为多个运行模式,在所提控制策略下系统在多个模式间实现平滑稳定切换。最后对运行中出现的分布式光伏电源输出波动和负载变化情况在MATLAB/Simulink进行了仿真实验。结果表明,所提策略能有效抑制系统直流母线电压波动和优化混合储能的运行,提高了系统的可靠性和稳定性,验证了控制策略的有效性和可行性。

基于MMC的超级电容与蓄电池混合储能系统及其混合同步控制策略

为满足储能系统提供惯量和一次调频支撑功能需要对多类型储能介质集中配置和优化调控的需求,针对基于模块化多电平换流器(modularmultilevelconverter,MMC)的新型混合储能系统(hybrid energy storage system,HESS)MMC-HESS,提出了混合同步控制(hybrid synchronous control,HSC)整体策略。MMCHESS采用模块化设计,将超级电容和蓄电池分别安置在高压直流母线侧和子模块内,具备高功率密度和高能量密度的优势。阐述了混合储能系统的拓扑结构和工作原理并采用混合同步控制策略提供系统惯量和一次调频功能及故障限流时的同步能力和孤岛并网切换功能,采用滤波器实现储能功率分配,采用荷电状态(state of charge,SOC)均衡控制实现蓄电池能量均衡。最后,基于硬件在环实验平台,验证了所提拓扑结构与控制策略的可行性和有效性。实验结果表明:所提混合储能系统及其控制策略具备惯量与频率支撑能力,在故障限流、正常并网、孤岛运行之间可灵活切换,能够有效发挥混合储能的综合优势,在中压配电网中具有良好的应用前景。

基于终端滑模自抗扰的混合储能系统功率控制

为提高混合储能系统对直流微电网母线功率支撑的双向调控性能,针对混合储能系统,提出一种基于非奇异终端滑模自抗扰技术的双向功率控制方法。分析建立采用双向半桥DC/DC变换器的并网接入系统数学模型;设计超级电容端电压稳定附加功率补偿控制结构;利用基于趋近律的非奇异终端滑模自抗扰技术和基于扩张状态观测器的系统不确定及扰动项在线估计,设计混合储能双向功率调节非线性控制器。通过仿真测试,并与传统线性控制器性能对比,验证所提方法的正确有效性。

基于A-MPC的MMC-HESS平抑光伏功率波动优化策略

为更好地解决光伏功率波动问题,提出一种光伏功率波动平抑及功率指令分配优化策略。首先,结合模块化多电平换流器-混合储能系统MMC-HESS(modular multilevel converter-hybrid energy storage system)提出自适应模型,预测控制实时平抑光伏功率波动,根据储能状态自适应调整目标函数;然后,提出霜冰算法优化的变分模态分解算法,双重分解储能总出力,完成MMC-HESS功率的初次分配;最后,通过充放电一致性优化、功率调整及模糊控制对功率分配指令进行双层优化。算例验证结果证明,所提策略能够有效平抑光伏功率波动,保护储能和优化HESS运行。

一种基于双环LADRC的混合储能变换器控制方法

混合储能变换器可以帮助提升光伏发电系统的动态响应能力和稳定性,但传统线性控制器在执行双向DC-DC变换器控制时表现不足。针对直流母线电压易受变换器非线性噪声、光伏输出功率和负载扰动影响的问题,设计了一种基于双环LADRC的混合储能变换器控制策略。通过分析混合储能变换器主电路的工作原理,建立了主电路的扰动模型。基于扰动模型完成了对电压-电流双环LADRC控制器的设计,并结合功率分频实现了混合储能变换器的整体控制策略。仿真结果表明,与传统比例积分控制器相比,基于双环LADRC的混合储能变换器控制策略使母线电压幅值波动减小了39.4%,调节时间减少了25.0%,在功率响应和直流母线电压支撑方面表现出优越的动态响应和抗扰能力。

基于分层主从协调结构的微电网智能管理系统

文中提出一种新的控制逻辑,通过分层主从架构中的分布式智能转换器,实现微电网中发电机、负荷和混合储能设备的智能管理。所提算法在较高的控制层面上运行,评估混合储能系统与所有资源(包括发电与需求)之间的最佳实现,以满足用户的用电需求,并确保电池储能系统参与电网平衡恢复过程所需的足够电力水平。为了验证所提方法的有效性,将提出的控制逻辑应用于并网住宅微电网进行仿真。在出现频率不稳定后,若不使用所提方法,电池储能系统中的电力在5 min内无法恢复;若使用所提方法,仅对电池储能系统进行操作时,恢复时间为2~5 min;而所提方法应用于电池储能系统‐双电层电容时,恢复时间缩短至不到1 min。仿真结果表明,将所提方法嵌入到主转换器和混合储能系统中,对于提高微电网储能系统为电网提供用户服务和辅助服务的性能非常有效。

新型混合储能运行模式分析与源荷储协调控制

储能是独立式光伏发电系统中的重要组成部分,可保证供电的稳定性和持续性,在提高电能质量方面起着重要作用。此处研究了一种混合储能系统(HESS)的新型拓扑结构和控制策略,该新型拓扑结构的优点在于对分布式系统中的双向直流-直流变换器额定功率要求低于传统系统。在运行模式切换时,控制系统可有效应对负载突变,确保蓄电池组和双向直流-直流变换器均工作于规定电压范围。此处建立了储能系统的数学模型和4种运行模式的控制模型,并对控制策略进行仿真和实验分析。仿真和实验结果表明新拓扑和控制策略可行,且HESS的性能不受双向直流-直流变换器的功率限制。

混合储能系统拓扑及其多模式综合协调控制

在分布式发电系统中,储能系统要同时具备高功率密度和高能量密度的特点,单种储能元件往往难以达到这个要求,蓄电池与超级电容在性能上具有很强的互补性。此处将蓄电池与超级电容分别通过双向半桥变换器连接到直流母线上构成混合储能系统(HESS),蓄电池稳定直流母线电压以维持母线上能量供需平衡,超级电容迅速提供负载波动功率高频分量,抑制负载突变对直流母线造成的冲击。分析了负载功率高频分量的检测方法,建立了双向半桥变换器的数学模型和4种模式下的控制策略。利用DSP实现储能系统的综合控制,通过仿真和实验验证了系统控制策略的有效性。

交直流电力系统与供热系统联合经济调度

随着热电联产等技术的广泛应用,电力系统和供热系统耦合日益紧密,电热联合调度得到了广泛的关注,但现有电热联合调度忽略了热网供电来源的多样性,由此提出了交直流电力系统与供热系统联合经济调度方法。首先,建立交直流电力系统模型,并提出一种线性近似方法对电压源变换器模型所带来的强非线性进行处理;然后,以运行成本最低为目标,建立考虑热网热惯性的交直流电力系统与供热系统联合调度模型,该模型中供热系统通过热电联产机组和交流电锅炉与交流电网耦合,通过直流电锅炉与直流电网耦合;最后,通过算例仿真验证了所提方法的有效性并说明了在电热联合调度中考虑交直流电源的必要性。

A comprehensive review on hybrid electric vehicles: architectures and components

The rapid consumption of fossil fuel and increased environmental damage caused by it have given a strong impetus to the growth and development of fuelefficient vehicles. Hybrid electric vehicles (HEVs) have evolved from their inchoate state and are proving to be a promising solution to the serious existential problem posed to the planet earth. Not only do HEVs provide better fuel economy and lower emissions satisfying environmental legislations, but also they dampen the effect of rising fuel prices on consumers. HEVs combine the drive powers of an internal combustion engine and an electrical machine. The main components of HEVs are energy storage system, motor, bidirectional converter and maximum power point trackers (MPPT, in case of solar-powered HEVs). The performance of HEVs greatly depends on these components and its architecture. This paper presents an extensive review on essential components used in HEVs such as their architectures with advantages and disadvantages, choice of bidirectional converter to obtain high efficiency, combining ultracapacitor with battery to extend the battery life, traction motors’ role and their suitability for a particular application. Inclusion of photovoltaic cell in HEVs is a fairly new concept and has been discussed in detail. Various MPPT techniques used for solar-driven HEVs are also discussed in this paper with their suitability.

Hybrid Loader Automatic Shift Strategy Based on Neural Network

Hybrid loader 's comprehensive performance mainly depends on the performance of hydraulic torque converter during its driving and working. Hybrid loader and hydraulic torque converter are taken for the research objects. The primary characteristic curve of hydraulic torque converter and the traction curve of hybrid loader are acquired by analyzing the characteristic parameters of hydraulic torque converter, the characteristic parameters of engine, the characteristic parameters of battery pack and geometric parameters of hybrid loader. The gear shift curves based on the best energy saving performance and the best power performance are acquired respectively with the opening of throttle,the speed of pump wheel and the speed of turbine as parameters. Then the two curves are combined to get the comprehensive gear shift curve. Radical basis function( RBF) neural network is applied to building the gear shift strategy to keep hybrid loader with the best power performance and energy saving performance. The experimental bench is set up for experimental verification. It proves that both of the power performance and energy saving performance of hybrid loader are improved effectively by using the automatic shift strategy.

适用于大规模纯新能源发电基地送出的混合式直流输电系统

为满足大规模纯新能源发电基地送出需求,经过拓扑比选,选取在送端采用电网换相换流器(LCC)与模块化多电平换流器(MMC)混合级联拓扑、受端采用二极管-模块化多电平换流器(DMMC)拓扑的混合式直流输电方案。其中,由整流站MMC提供送端交流电压支撑,并与LCC配合作为送出功率平衡中转站。随后,设计系统的基本控制和故障穿越策略,使系统能够稳定送出新能源功率且兼具经济性与故障穿越能力。最后,在PSCAD/EMTDC中搭建±800 kV/5000 MW双极直流输电仿真模型,验证所提控制与故障穿越策略的有效性,结果表明:所选拓扑适用于大规模纯新能源发电基地送出场景。