基于混合储能系统的微电网母线电压控制策略

在孤岛直流微电网中,母线电压是判断其稳定性和衡量电能质量的唯一指标。针对这一现象,在孤岛直流微电网中加入了由蓄电池-超级电容组成的混合储能单元来平抑微电网系统中出现的波动功率,同时对于超级电容控制器添加了补偿电流来提升控制精度,差额功率经过低通滤波器后,高频分量经超级电容器平抑,低频分量经蓄电池平抑,对于母线电压不论是瞬时恢复还是长期的稳定性都得到了保障。试验结果表明,不论是光照强度变化还是负载功率变化,含混合储能系统的微电网母线电压都能快速恢复至额定值,无论是电能质量,还是系统稳定性都具有一定的提升。     

有功和无功功率可调的级联式电能装置及其控制方法

为了对可再生能源发电系统输出的波动有功功率进行调节,提高电力系统的电能质量和可靠性：本文基于已有的级联式电力电子变换装置,论及了一种同时具有有功功率和无功功率调节的电能装最。基于该装置在d,q坐标系下的数学模型,提出一种在有功功率以及无功功率调节时的直流侧电压控制方法。最后,利用MATLAB仿真工具对6kV,3MW／MVA的系统进行仿璇,仿真结果验证了系统的可行性和有效性。     

高压级联SVG电流PR控制策略

对SVG在出现无功阶跃扰动时的补偿控制进行深入研究。SVG在无功功率调节时,如果出现阶跃扰动,无功功率的调节会直接影响有功功率的调节,这是因为传统的旋转坐标系控制方法对于有功功率和无功功率的控制环路之间存在耦合关系。为此,文中引入了有功和无功的解耦控制。另外,无功的阶跃信号会引起直流母线电压的突变,故将直流分量引入装置侧输出电流的值,并将这个直流分量滤除,保证控制的稳定性。最后在仿真的基础上,以光伏电站为背景对所提方法进行现场验证,结果充分证明了该算法的有效性。     

三相电压暂变补偿装置控制策略的研究

提出了一种三相电压暂变补偿装置的主电路拓扑。该方案利用线电压对直流母线电容充电,扩大了补偿电压的范围。针对此方案对三相电压暂变进行独立补偿,采用了补偿装置的三角波比较控制方法,通过对比3种常见的控制策略的原理,最终给出了采用能量最优控制法系统的仿真结果和主电路补偿的实验结果。     

自适应电压控制器在UPQC直流侧的仿真应用

统一电能质量控制器(UPQC)的一个显著特性是用直流电容器取代直流电源,而直流电容器的电压变化会影响电源的有功功率平衡.为保证UPQC主电路能实时跟踪指令电流的变化进而产生恰当的补偿电流,必须使直流侧电容电压保持恒定.通过采取自适应电压控制器控制直流侧电压的输出来补偿系统损耗,从而保证直流侧电压恒定.利用MATLAB仿真软件对此控制策略进行仿真建模,获得了比较理想的直流侧电压,验证了此方法的有效性.     

三相四开关整流器的研制

三相四开关整流器拓扑具有功率器件少、成本低、装置体积小、效率高和开关损耗低等优点,同时又可作为三相六开关整流器故障时的容错拓扑,因此三相四开关整流器受到广泛关注.本文首先介绍了三相四开关整流器的主电路,并且提出一种电流前馈型解耦的电压电流双闭环控制策略.为了抑制直流侧两电容电压不平衡的情况,采用了一种前馈补偿的控制策略...     

基于坐标变换的间隙性功率并网系统解耦控制与设计

针对逆变器电流环的有功电流和无功电流存在耦合的情况,文中采用电流的解耦控制,达到独立控制逆变器的有功功率和无功功率;针对逆变器直流侧电压容易波动,文中采用双环控制,稳定逆变器直流侧的电压。搭建了MA-TALAB/SIMULINK系统仿真实验平台,通过间歇性能源输入逆变器功率变化的实验,验证了该逆变器能独立控制输出的有功功率和无功功率,并且保证了直流侧电压的稳定。     

串联电容补偿线路距离保护研究

随着大容量远距离输电的发展,串联电容补偿技术在超高压、远距离输电中得到了广泛应用。文中介绍了串联电容补偿装置的构成、工作原理,以及等效模型的不同工作方式,分析了MOV的工作特性。串联电容补偿技术是一项成熟的技术,通过串联电容补偿线路感抗,缩短交流传输的电气距离,降低线路输送损耗,改善线路的电压质量,提高线路传输功率,更加合理地分布输送功率,提高系统的动态稳定和静态稳定性。     

基于一种电压优化补偿装置的研究

随着大功率家用电器的迅速普及,居民用电年均速度递增。快速增加的居民用电态势,使低压线路末端电压逐渐偏低的问题日益严重,给广大用电客户带来了极大的不便,也给供电企业的优质服务带来了极大的挑战,低电压已成为当前电力客户普遍关注的焦点。本文主要论述一种电压优化补偿装置的研究,该装置优化电压及无功功率补偿,能减少电能损失,节省空间,并实现实时对线路各参数进行检测的电压优化补偿。     

大城市电网链式STATCOM关键技术研究

文章介绍了链式STATCOM的拓扑结构,在此基础上建立了数学模型。直流侧电容电压平衡控制是链式STATCOM的一个关键技术问题,针对此问题,采用了一种分级协调控制策略,通过改变H桥单元的输出电压和电流的夹角从而调整吸收／释放的有功功率,最终控制直流侧电容电压平衡。最后,搭建了仿真模型,仿真结果验证了控制策略的正确性和可...     

间歇式能源发电系统无功补偿技术的研究

针对间歇式能源发电系统的特点和无功需求,提出了将无功补偿与风力并网发电相结合的设计方案,通过计算得出了间歇式能源发电系统中电缆和变压器无功损耗.本文利用Mat-lab/Simulink搭建了具有无功补偿功能的并网变流器的仿真模型,并采用有功无功解耦控制和SPWM控制方法,补偿系统所需无功以及有效抑制动态电压波动.最后,仿真结果验证了风力并网变流器在向电网提供有功功率的同时也能够提供一定容量的无功功率,提高系统功率因数,有效抑制电网电压波动.     

A novel active power filter based on the least compensation currentcontrol method

A new least compensation current technique to detect the harmonic and reactive current for active power filters is presented in this paper. With the technique, a novel active power filter based on the least compensated current control is proposed, in which the measurement of harmonic and reactive current and the generation of compensated current are completed in the same closed-loop. Compared with the existing control methods of active power filter, the proposed method has simpler structure, quicker dynamic, higher reliability and better compensation performance. Simulating and experimental results are provided that verified theoretical predictions and demonstrate the effectiveness of the proposed control method and circuit configuration     

基于PMSG的风电系统并网控制策略研究

针对直驱型风力发电不控整流＋Boost＋PWM逆变器并网拓扑结构,利用Matlab/Simulink软件平台,搭建了整个并网系统的仿真模型,并对网侧PWM逆变器进行了控制策略的研究。仿真结果表明,这种控制策略能稳定直流电压,使风电机组能正确地并入电网,实现了有功、无功的解耦及单位功率因数控制。     

Improved Direct Power Control of Grid-Connected DC/AC Converters

This paper proposes new direct power control (DPC) strategies for three-phase dc/ac converters with improved dynamic response and steady-state performance. As with an electrical machine, source and converter flux, which equal the integration of the respective source and converter voltage, are used to define active and reactive power flow. Optimization of the lookup table used in conventional DPC is outlined first so as to improve power control and reduce current distortion. Then, constant switching frequency DPC is developed where the required converter voltage vector within a fixed half switching period is calculated directly from the active and reactive power errors. Detailed angle compensation due to the finite sampling frequency and the use of an integral controller to further improve the power control accuracy are described. Both simulation and experimental results are used to compare conventional DPC and vector control, and to demonstrate the effectiveness and robustness of the proposed control strategies during active and reactive power steps, and line inductance variations.      

Two-stage voltage control strategy for PV plants based on variable droop control

ABSTRACT

Voltage violation is an important factor that restricts grid-connected photovoltaic system. The utilization of PV plant’s reactive power capability is an effective measure to mitigate voltage violation. This paper proposes two-stage voltage control strategy to enhance the voltage support capability of photovoltaic grid-connected system. In first stage, adaptive gains are set according to the maximum reactive capacity of each PV plant in order to distribute reactive power among PV plants more reasonably, avoiding certain PV plants operating in the limit state for a long time. In second stage, when the reactive power capacity is insufficient, the priority of active power curtailment for each PV plant is calculated in real time. Active power curtailment control will be performed in PV plants with high priority to released more reactive power capacity for voltage support. The simulation results carried out by PSCAD/EMTDC software demonstrated that this strategy can effectively solve the voltage violation problem. Meanwhile, the proposed strategy not only can exploit reactive capacity of each PV plant as much as possible to avoid certain PV plants operating in the limit state for a long time, but also can reduce the amount of active power curtailment when reactive power adequacy is insufficient.     

光伏并网逆变器电压型控制技术研究

本文主要对电压源电压型并网控制技术进行了研究.根据逆变器并联运行中的无功调幅.有功调频的控制原理,将此方法应用到光伏并网逆变器中实现了有功和无功的独立控制.使得逆变器在输出功率上控制更加灵活详细讨论了电压型并网控制算法,并给出了关键模块I_(d)、I_(q)。的计算方法和正弦波合成器的实现过程最后.在Matlab/Simulink中建立了仿真模型,并进行了实验验证.仿真和实验结果表明电压型并网控制方案具有可行性。     

基于71M6513的低压无功补偿控制器设计

传统无功补偿控制器普遍采用ADC MCU模式来测量电网电压、电流,计算有功、无功、功率因素等参数,具有硬件设计复杂、软件编程量大、抗干扰能力差等缺点.本文提出了基于TDK 71M6513的智能化低压无功补偿控制器,该控制器集成电网电压、电流参数采集,无功、有功、功率因素等参数计量,数据管理与输出控制于一体.本文给出了控制器的结构组成与工作原理、各单元模块电路以及系统软件流程设计,并对控制器实际工作性能进行了测试与结果分析.     

A Model-Based Direct Power Control for Three-Phase Power Converters

The direct power control (DPC) technique has been widely used as a control strategy for three-phase power rectifiers due to its simplicity and good performance. DPC uses the instantaneous active and reactive power to control the power converter. The controller design has been proposed as a direct control with a lookup table and, in recent works, as an indirect control with an inner control loop with proportional-plus-integral controllers for the instantaneous active and reactive power errors. In this paper, a model-based DPC for three-phase power converters is designed, obtaining expressions for the input control signal, which allow the design of an adaptive control law that minimizes the errors introduced by parameter uncertainties as the smoothing inductor value or the grid frequency. A controller design process, a stability study of the system, and experimental results for a synchronous three-phase power rectifier prototype are presented to validate the proposed controller.