孤立微电网的可再生能源系统 翻译版

1、学号：1512306002 姓名：方治 专业：控制理论与控制工程 日期：2016年3月A novel modeling methodology of open circuit voltage hysteresis for LiFePO4 batteries based on an adaptive discrete Preisach model对磷酸铁锂电池基于自适应离散Preisach模型开路电压滞后的一种新的建模方法Letao Zhu, Zechang Sun, Haifeng Dai Corresponding author at: School of Automotive Studie

2、s, Tongji University, No. 4800, Caoan Road, Shanghai 201804, China. Tel.: +86 02169583847.E-mail address: tongjidai (H. Dai).State of chargeFig. 1. OCV-SOC characteristics of LiMn24 and LiFeP4 batteries (OCV hysteresis is ignored for simplicity)., Xuezhe Wei National Engineering Laboratory for New E

3、nergy Automotives and Powertrain Systems, Tongji University, No. 4800, Caoan Road, Shanghai 201804, China School of Automotive Studies, Tongji University, No. 4800, Caoan Road, Shanghai 201804, ChinaAbstractThis paper presents the development of the power electronics needed for the interaction betwe

4、en the electrical generator of a wind turbine and an isolated ac micro grid. In this system there are basically two types of receptors for the energy produced by the wind turbine, which are the loads connected to the isolated micro grid and the batteries used to store energy. There are basically two

5、 states in which the system will work. One of the states is when there is enough wind power to supply the loads and the extra energy is used to charge the batteries. The other state is when there is low wind power and the batteries have to compensate the lack of power, so that the isolated micro gri

6、d has enough power to supply at least the priority loads. In this paper are presented the hardware and the control algorithm for the developed system. The topology was previously tested in computer simulations, using the software PSIM 9.0, and then validated with the implementation of a laboratory p

7、rototype.摘要-本文介绍了风力涡轮机和一个隔离的交流微电网之间的相互作用所需要的电力电子设备的发展。在这个系统中，基本上有风力涡轮机所产生的2种类型的能量，它们是连接到隔离的微电网和电池用于存储能源的能量。系统基本上有两个工作状态。其中一个状态是有足够的风力能量供电负载和额外的能量是用来充电的电池。另一方面是当有低的风电功率时，电池必须补偿功率的不足，使隔离微电网至少有足够的电力供应优先负载。在本文中，提出了硬件和控制算法的开发系统。拓扑是以前利用软件PSIM 9测试的计算机模拟，然后验证实验室原型的实现。KeywordsHysteresis, Open circuit voltage

8、, State of charge, Adaptive discrete Preisach model关键词：磁滞现象，开路电压，充电状态，自适应离散Preisach模型I. INTRODUCTIONI. 简介In order to reduce fossil fuels dependency in the production of electrical energy, there has been an increase in the installation of renewable energies 1. In Europe, since 2000, wind, photovoltai

9、c solar and gas installed power has increased 115.4 GW, 80 GW and 131.7 GW, respectively. On the other hand, fuel oil, coal and nuclear installed power sources have decreased 28.7 GW, 19 GW and 8.5 GW, respectively 2. The main reason for these changes is the fact that the renewable energies have a c

10、lean production and so, there is no production of residual products that fossil energy sources produce 3. Also, renewable energies are an unlimited source of energy, contrasting with fossil fuels, which, for example, oil, is starting to grow scarce.为了减少生产电能时对化石燃料的依赖，增加了再生能源的安装1。在欧洲，自2000年以来，风能，太阳能光伏

11、和安装的燃气功率分别增加了115.4万千瓦，80万千瓦和131.7万千瓦。在另一方面，燃料油，煤炭和核能装机容量分别2下降28.7吉瓦，19吉瓦和8.5吉瓦。这些变化的主要原因是，可再生能源有一个干净的生产等，没有生产化石能源产生3的残余产物。另外，可再生能源是不会枯竭的能源，与化石燃料相比，例如，油，正在开始变得稀少。按段翻译，一段英文后一段中文The wind power is a source of energy that has been increasing in its installed power around the world 4. It is mainly used in

12、 grid tied applications, where the energy extracted from the wind is injected in the power grid 56. There is another kind of application to this type of energy source, which is an off-grid system, also known as isolated system. In this system, the energy provided by the wind system must satisfy the

13、needs of the loads connected to a micro grid. However, since this system is dependent on one source of energy that is not constant, batteries are used to smooth the intermittent energy produced by the wind turbine, therefore making possible to power the micro grid even when there is no wind. Additio

14、nally, this system can be complemented with another type of energy source, for example, photovoltaic solar energy or a diesel engine-generator system 7. This makes the system more stable since it has another reliable energy source to compensate the lack of wind, turning the system into a hybrid one

15、8. Since the micro grid is reliant on the energy generated by the sources connected to it and the batteries that are used to store the extra produced energy, there can be moments in which the available energy will be lower than required, leading to a need to disable some lower priority loads to save

16、 energy 9. All of these factors need to be taken in account when designing the system. These off-grid systems are normally used when extending the main grid to the desired location is more expensive compared to creating a micro grid to satisfy those needs 10. The existing micro grids are normally co

17、mposed by a diesel engine-generator source, however as most of these zones are of difficult access, the transportation of the required fuel can pose a problem. In addition, the noise caused can also become a disturbance. The problem is reduced by the introduction of renewable energies 11. Comparing

18、the quality of the energy produced by these two sources, as the renewable energies use controlled power electronics inverters they are less affected by the variation of loads, producing a voltage with better quality compared to the diesel engine-generator systems 12.风力发电是能量的来源，全世界4一直在增加其装机容量。它主要用于在电

19、网捆绑的设备，从风中提取的能量并注入电网56。对这种类型的能量源还有另一种类型的应用程序，这是一个离网系统，也被称为孤立系统。在这个系统中，由风力系统提供的能量必须满足连接到微电网的负载的需要。然而，由于该系统是依赖于不恒定的能量源，电池被用于平滑由风力涡轮机产生的间歇性能源，因此可能给微电网提供能量，即使没有风的时候。此外，该系统可以用另一类型的能量源来补充，例如，光伏太阳能或柴油发动机- 发电机系统7。这使得系统更加稳定，因为它具有另一种可靠的能源用来补偿风能的不足，使该系统变成混合的系统8。由于微电网是依赖于由连接到它的源和用于存储额外的所产生的能量，有时候可用的能量比需求低， 的电池所

20、产生的能量，可以有时刻在其中的可用能量会比需要低，导致需要禁用一些低优先级的负载，以节省能源9。当设计系统时，所有这些因素都需要考虑。这些脱离系统的微网通常使用在，为满足这些负荷需求10，延伸主电网到所需的位置比创建一个微电网更昂贵的地方。现有的微电网通常由柴油发动机 - 发电机源组成，但是因为大多数这些区域是难以进入的，所需要的燃料的输送成为问题。此外，引起的噪声也可以成为一个干扰。该问题可以通过引入可再生能源11降低。比较通过这两个源产生的能量的质量，因为可再生能源使用控制功率电力电子变换器，它们较少受各种载荷影响，相比于柴油发动机 - 发电机系统12产生更好质量的电压。In terms

21、of power electronics converters for micro-wind turbines several topologies have been proposed. In 13, it is presented a single-phase topology for energy extraction from wind turbines. However, this type of topology is not suitable to work in isolated mode, since there is no device that can store ene

22、rgy, making the system unreliable. In 14, it is proposed another topology, this one though, works in isolated systems, but is not ideal when generators with high voltage output and low voltage batteries are used, since the dc-dc buck-boost converter is not suitable to reduce the voltage from high le

23、vels to low levels. Fig. 1 shows a block diagram of the proposed micro-wind system. The ac voltage produced by the electrical generator is converted to dc by a rectifier. 就在电力电子转换器而言，用于微型风力涡轮机的几个拓扑已被提出。在13，它提出了一种单相拓扑用于从风力涡轮机提取能量。然而，这种类型的拓扑结构不适合在孤立模式下工作，因为没有设备能够存储能量，使得系统不可靠。在14，提出另一拓扑，这一个虽然可以工作在分离系统，

24、但是当发电机具有高电压输出和使用电压电池时，它是不理想的，因为DC-DC降压 - 升压转换器不适合降低从高电压等级到低电压等级的电压。图.1所示，所提出的微型风力系统的框图。由发电机产生的交流电压被整流器转换成直流。Fig. 1. Micro-wind isolated system block diagram.图.1. 从系统孤立的微网的系统框图。图要剪切贴上，图标文字要翻译Fig. 2. Electrical diagram of the proposed micro-wind isolated system.图.2 所提出的从系统中孤立的微型风力系统的电气原理图。The full-bri

25、dge buck-type dc-dc converter optimizes the energy extraction and manages the batteries charging. This type of converter is normally used in high power systems, allowing a better control over the level of the voltage in the output 15. The inverter is used to produce a sinusoidal voltage with the des

26、ired frequency and amplitude to supply the loads.全桥降压型直流 - 直流转换器最优化的能量提取和管理电池充电。这种类型的转换器通常用于高功率系统中，可以更好的控制输出15电压的等级。所需的频率和振幅II. SYSTEM ARCHITECTUREII. 系统的结构In this item, it is presented the system architecture used in the current application. As shown in Fig. 2 this system is composed by three power

27、 converters: an ac-dc bridge rectifier; a dc-dc full-bridge buck-type; and a dc-ac full-bridge. The ac-dc bridge rectifier is only used to convert the ac voltage from the generator to a dc voltage. Furthermore, the dc-dc full-bridge buck-type converter is used to convert the voltage from the output

28、of the ac-dc converter to the desired level, which will be applied to charge the batteries. Finally, the dc-ac full-bridge converter is used to convert the dc link voltage to a low distortion sinusoidal voltage with the desired amplitude and frequency. A more detailed analysis of these converters is

29、 further presented.在这个项目中，提出的系统结构使用在当前应用中。如图.2所示，这个系统是由三个电源变换器组成：一个交流 - 直流桥式整流器;一个直流 - 直流全桥降压型变换器;和一个直流 - 交流全桥逆变器。该交流 - 直流桥式整流器只用于从发电机发出的交流电压转换为直流电压。此外，DC-DC全桥降压型转换器用于将从交流 - 直流转换器的输出电压转变为所要求的电压等级，这将被应用到给电池充电。最后，DC-AC全桥转换器用于将直流电路电压转换为所希望的幅度和频率的低失真正弦电压。这些转换器的更详细的分析，将进一步提出。Besides the three converters,

30、 the system is also composed by a permanent magnet synchronous generator (PMSG), which the output voltage and maximum power is a function of the wind velocity. To prevent that the generator reaches rotational velocities greater than the nominal it is used an electrical brake system. This system is a

31、ctivated when the wind turbine velocity reaches a certain value in which it can damage the generator or other mechanical components. Also, when the batteries are fully charged and the energy produced by the generator is superior to what is needed by the loads, the brake will also serve as a mean to

32、dissipate the incoming energy. It is also used an output transformer to adapt the voltage that is applied to the loads, which is necessary due to the batteries low voltage.除了三个转换器，该系统的组成部分还有一个永磁同步发电机（PMSG），它的输出电压和最大功率是一个风速的函数。为了防止发电机旋转速度大于额定值，它使用电子制动系统。当风力涡轮机的速度达到一定值，此值可能会损坏发电机或其它机械部件，此系统被激活。此外，当电池满

33、电，由发电机产生的电能优先给所需要的负荷，制动器也将作为一种方式消耗散传入的能量。它也用输出变压器，来调节电压以适应被施加到负载，由于电池电压低这是必要的。A. Dc-dc Full-Bridge Buck-Type ConverterA. 直流直流全桥降压转换器This section presents the description of the dc-dc full-bridge buck-type converter. The objective of this converter is the regulation of the dc link voltage (vDC), whic

34、h at the same time allows the implementation of the maximum power point tracker (MPPT) control algorithm. This converter is controlled by applying PWM signals to the IGBTs in order to produce a square output voltage with variable duty-cycle in the full-bridge output. These PWM signals are created by

35、 comparing the voltage reference with a high frequency triangular carrier waveform. The output voltage amplitude of this converter will be reduced by the high-frequency transformer with center-tapped secondary winding. The transformer secondary winding is connected to a two diode full-wave voltage r

36、ectifier to obtain a positive voltage. 本节介绍DC-DC全桥降压转换器。此转换器的作用是调节直流链路电压(vDC)，它同时允许的最大功率点跟踪（MPPT）控制算法的执行。此转换器是通过将PWM信号提供给IGBT进行控制的，以便产生一个在全桥输出的可变占空比的方输出电压。这些PWM信号是通过比较参考电压和一个高频载波三角波形发生的。此转换器的输出电压振幅通过中心抽头二次绕组的高频变压器减小。变压器二级绕组被连接到两个二极管的全波电压整流，以获得一个正电压。公式要剪切贴上或用编辑工具编辑The output voltage can be calculated

37、 with (1). in which vDC is the output voltage, v1 the input voltage, the duty-cycle of the output voltage of the high-frequency transformer and n the relation of turns of the transformer. Fig. 3 shows the simulation results of this converter. In Fig. 3 (a) it is shown the voltage (vP) applied to the

38、 high-frequency transformer and its secondary output voltage (vs) , for an input voltage (v1) of 90V and a duty-cycle () of 50%. In Fig. 3 (b) it is shown the output voltage of the converter (vDC) and the current in the inductor (iL1) in continuous conduction mode. It is possible to observe that the

39、 current in the inductor varies in accordance with the voltage applied to it, never getting to zero. In this application it is important to have a transformer with low leakage inductance in order to avoid duty-cycle related problems of the voltage in the secondary of the transformer, which would lea

40、d to a voltage lower than expected in the output of the converter.输出电压可以用（1）计算。其中vDC是输出电压，v1是输入电压，是高频变压器输出电压的占空比和n变压器的匝数。图.3所示，该转换器的仿真结果。在图3（a）中，电压(vP)施加到高频变压器及其次级输出电压(vs)，对于90V的输入电压(v1)和50的占空比。在图.3（b）中，转换器的输出电压（v_DC），和电感器（i_L1）的电流工作在连续导电模式下。能够观察到，在电感器中的电流根据电压变化，从未达到零。在这个应用中，拥有一个低漏感的变压器是很重要的，为了避免电压在

41、变压器的次级绕组中的相关占空比问题，这可能导致转换器的输出电压比预期的低。Fig. 3. Simulation results of the dc-dc full-bridge buck-type converter: (a) Primary voltage (vP) and secondary voltage (vs); (b) Dc link voltage (vDC) and inductor current (iL1).图.3 直流-直流全桥降压转换器的仿真结果：（a）一次电压(vP)和二次电压(vs); （b）直流母线电压(vDC)和电感电流(iL1)。As aforemention

42、ed, besides regulating the output voltage, this converter must also implement a MPPT control algorithm aiming to extract the maximum power that the generator can produce in function of the wind speed.如前面提到的，除了调节输出电压，该转换器还必须实现MPPT控制算法，旨在以提取该发电机可在风速函数产生的最大功率。Two different types of MPPT were evaluated:

43、 power signal feedback; and perturbation and observation. The power signal feedback permits a better control over the current and also a better efficiency in the extraction of power. Nevertheless, this control needs the power curve of the generator, which can be considered a drawback. The perturbati

44、on and observation is a more basic control, which permits the extraction of the maximum power with acceptable efficiency. This control does not need any information about the generator and so permits an easier use. The results presented in this work are achieved with the perturbation observation alg

45、orithm. This control applies a step variation (perturbation) in the duty-cycle of the dc-dc converter and observes how the system reacts. The imposed perturbation on the duty-cycle can be positive or negative. If after a positive perturbation the extracted power increases, the next perturbation will

46、 be in the same way (incrementing again the duty-cycle). Else if the extracted power reduces, negative perturbations (reductions in the duty-cycle) will be applied while the extracted power increases. With this algorithm the extracted power follows the maximum available power. Fig. 4 shows the flowc

47、hart of the perturbation and observation MPPT algorithm.两种不同类型的MPPT的评价：功率信号反馈;和扰动和观察。功率信号反馈允许更好地控制电流以及在更好的效率提取功率。然而，这种控制需要发电机的功率曲线，它可以被认为是一个缺点。该扰动和观察是一个更基本的控制，这允许最大功率以可接受的效率的摄取。这种控制并不需要关于发电机的任何信息，因此允许更容易使用。这项工作中呈现的结果用扰动观测算法来实现。该控制在直流 - 直流转换器的占空比应用步骤变化（扰动）和观察系统如何反应。在占空比的施加扰动可以是正数或负数。如果一个正扰动后所提取的功率的增加

48、，下一个扰动会以同样的方式（再次递增占空比）。否则，如果所提取的功率减少，当提取的功率的增加时，负的扰动（减少占空比）将被应用。用此算法，所提取的功率跟随最大的可用功率。图4所示，扰动的流程图和观察MPPT算法。Fig. 4. Flowchart of the Perturbation and Observation MPPT control algorithm.图.4. 扰动的流程图和观察MPPT控制算法Fig. 5. Simulation results of the extracted power (p) and the maximum theoretical power of the

49、generator (p*) for different wind speeds.图.5 提取的功率(p)和对于不同风速的发电机(p*)的最大理论功率的仿真结果。In Fig. 5 it is shown the obtained results using the aforementioned algorithm. It is possible to verify that the extracted power (p) follows the theoretical maximum power possible to extract from the generator (p*) for

50、different wind speeds. By applying an MPPT algorithm the maximum power extracted at each instant is used to feed the load and the reminiscent, if it exists, to charge the batteries. So, with this technique the batteries are always being charged or discharged in function of the available wind and the

51、 load consumption. However, the system is constantly monitoring the batteries voltage to prevent overcharges or overdischarges.在图.5中表示，使用上述算法所获得的结果。它可以验证所提取的功率(p)跟随理论最大功率，它可能从对不同的风速的发电机(p*)提取。通过运用MPPT算法，在每个瞬间提取的最大功率被用于供给负荷和让人联想，如果存在，给电池充电。因此，使用这种技术的电池总是被充电或放电，用可用风和负载消耗的函数。然而，该系统不断地监视电池电压，以防止过充或过放。B.

52、 Dc-ac Full-Bridge ConverterB. 直流-交流全桥变换器This section presents the description of the dc-ac full-bridge converter. This converter in addition with an output transformer allows the conversion of the voltage from the dc link to an ac voltage with 230 V RMS and 50 Hz of frequency that will be applied t

53、o the loads. The switching technique used in this converter to obtain the pulses pattern applied to the MOSFETs was the unipolar synchronized pulse-width modulation (SPWM). This technique consists in comparing a high frequency triangular carrier waveform with a sinusoidal waveform reference for one

54、of the legs of the converter, and another sinusoidal reference lagged by 180 to the other leg. The result of each comparison is applied to the top MOSFET and the result negated is applied to the other MOSFET in the same leg.本节提出了DC-AC全桥转换器的介绍。此转换器，除了用输出变压器允许把直流电路电压转变为230伏和50赫兹频率的交流电压，此电压将被运用到负载上。使用在

55、此转换器，为获得运用到MOSFET的脉冲模型的开关技术是单极同步脉宽调制（SPWM）。这种技术通过比较，用变换器的一支的一个高频率三角载波波形与正弦波参考值，另一个正弦参考值比另一支滞后180组成。Fig. 6. Diagram of the dc-ac converter control.图.6. 直流 - 交流转换器控制的框图。Fig. 7. Simulation results of the dc-ac converter: output voltage (v0) and output current (i0).图.7 直流 - 交流转换器的仿真结果：输出电压(v0)和输出电流(i0)。

56、In theory, the reference will be a sinusoidal waveform and its frequency will be equal to the frequency desired to the output voltage. The amplitude of output voltage can be calculated by using (2).从理论上说，参考值将是一个正弦波，其频率将等于所希望的输出电压的频率。输出电压的幅度可以通过使用（2）来计算。where, VOP is the amplitude of the output volta

57、ge, and ma the modulation index, which is calculated by:其中，VOP是输出电压的幅值，ma是调制指数，通过如下公式计算：in which, VTP is the maximum amplitude of the triangular carrier waveform, and VRP the maximum amplitude of the reference signal waveform. It is important refer that the VTP must have the same amplitude of the dc

58、-link voltage. In practice, it is needed a dead-time between the control signals of a given converter leg to avoid a short circuit during the switching of the MOSFETs. However, introducing this dead-time creates a distortion in the output voltage. Also, the various existing loads will create another

59、 source of distortion. It is then needed to apply some changes to the SPWM control. Fig. 6 shows the control diagram of the dc-ac full-bridge converter. This control diagram is mainly based in a PI controller and a feedforward component to enable a faster response of the system to the desired output voltage (v0*) . This control will change