## 物理代写|光电技术代写Photovoltaic Technology代考|EGV2101

statistics-lab™ 为您的留学生涯保驾护航 在代写光电技术Photovoltaic Technology方面已经树立了自己的口碑, 保证靠谱, 高质且原创的统计Statistics代写服务。我们的专家在代写光电技术Photovoltaic Technology代写方面经验极为丰富，各种代写光电技术Photovoltaic Technology相关的作业也就用不着说。

• Statistical Inference 统计推断
• Statistical Computing 统计计算
• (Generalized) Linear Models 广义线性模型
• Statistical Machine Learning 统计机器学习
• Longitudinal Data Analysis 纵向数据分析
• Foundations of Data Science 数据科学基础

## 物理代写|光电技术代写Photovoltaic Technology代考|Common-Mode Behavior

The transformerless technology offers high-efficiency PV inverter at reduced cost. This explained why the PV inverter trend is moving toward transformerless topology. In order to understand the fundamental principle of the transformerless topology, the common-mode behavior will be analyzed here based on single-phase system. The similar common-mode behavior analysis can be extended to three-phase system, and thus the three-phase analysis will not be covered here.
When the transformer is removed from PV inverter, galvanic connection is formed between the PV arrays and the grid. This galvanic connection creates a leakage current path as shown in Fig. 12. When the CMV is produced by the inverter topology with corresponding pulse width modulation (PWM), the CMV charges and discharges the stray capacitance. As a result, leakage current is generated, flowing through the leakage current path between the PV arrays and the grid. In order to design a suitable transformerless PV inverter topology with reduced leakage current, the common-mode behavior must first be understood. A common-mode model circuit is derived here and simplified stage by stage to study the common-mode behavior of the transformerless PV inverter.

For transformerless inverter, a resonant circuit is formed as shown in Fig. $13 .$ This resonant circuit includes the parasitic capacitance $\left(C_{\mathrm{PV}}\right)$, the filter inductors $\left(L_1\right.$ and $L_2$ ), leakage current $\left(I_L\right)$. Here, the power converter is represented by a block with four terminals to allow a general representation of various converter topologies. On the DC side, $P$ and $N$ are connected to the positive and negative terminal of the DC link respectively; while on the $\mathrm{AC}$ side, terminals $\mathrm{A}$ and $\mathrm{B}$ are connected to the single-phase grid via filter inductors [15].

From the view of point of grid, the power converter block as shown in Fig. 14 can be considered as voltage sources, generating into equivalent circuit which consists of $V_{\mathrm{AN}}$ and $V_{\mathrm{BN}}$. Obviously, the leakage current is a function of $V_{\mathrm{AN}}, V_{\mathrm{BN}}$, grid voltage, $L$ and $C_{\mathrm{PV}}$. Since the grid is a low-frequency voltage source ( 50 or $60 \mathrm{~Hz}$ ), the impact on the common-mode model will be ignored here. Therefore, a simplified common-mode is obtained as shown in Fig. 15 by expressing voltages $V_{\mathrm{AN}}$ and $V_{\mathrm{BN}}$ as the functions of $V_{\mathrm{CM}}$ and $V_{\mathrm{DM}}$.

## 物理代写|光电技术代写Photovoltaic Technology代考|Galvanic Isolation

In transformerless PV inverter, the galvanic connection between the PV arrays and the grid allows leakage current to flow. The galvanic isolation can basically be categorized into DC decoupling and $\mathrm{AC}$ decoupling methods. For DC decoupling method, DC bypass switches are added on the DC side of the inverter to disconnect the PV arrays from the grid during the freewheeling period. However, the DC bypass branch, which consists of switches or diodes, is included in the conduction path as shown in Fig. 16. The output current flows through two switches and the two DC bypass branches during the conduction period. Hence, the conduction losses increase due to the increased number of semiconductors in the conduction path.

On the other hand, bypass branch can also be provided on the AC side of the inverter (i.e., AC decoupling method). This AC bypass branch functions as a freewheeling path which is completely isolated from the conduction path, as shown in Fig. 17. As a result, the output current flows through only two switches during the conduction period. In other words, topologies employing AC decoupling techniques are found to be higher in efficiency as compared to DC decoupling topologies.

One setback of galvanic isolation is that there is no way of controlling the CMV by PWM during the freewheeling period. Figures 18 and 19 show the operation modes of galvanic isolation topology which employs DC decoupling method (one DC bypass branch) during the positive half-cycle. As indicated in Fig. 18, during the conduction period, $S_1$ and $S_4$ conduct to generate the desired output voltage. At the same time, $V_{\mathrm{A}}$ is directly connected to $V_{\mathrm{DC}}$ and $V_{\mathrm{B}}$ is connected to the negative terminal $(N)$ of the DC link. Hence, the CMV becomes
$$V_{\mathrm{CM}}=\frac{V_{\mathrm{AN}}+V_{\mathrm{BN}}}{2}=\frac{1}{2}\left(V_{\mathrm{DC}}+0\right)=\frac{V_{\mathrm{DC}}}{2}$$

## 物理代写|光电技术代写光伏技术代考|电隔离

$$V_{\mathrm{CM}}=\frac{V_{\mathrm{AN}}+V_{\mathrm{BN}}}{2}=\frac{1}{2}\left(V_{\mathrm{DC}}+0\right)=\frac{V_{\mathrm{DC}}}{2}$$

## 有限元方法代写

tatistics-lab作为专业的留学生服务机构，多年来已为美国、英国、加拿大、澳洲等留学热门地的学生提供专业的学术服务，包括但不限于Essay代写，Assignment代写，Dissertation代写，Report代写，小组作业代写，Proposal代写，Paper代写，Presentation代写，计算机作业代写，论文修改和润色，网课代做，exam代考等等。写作范围涵盖高中，本科，研究生等海外留学全阶段，辐射金融，经济学，会计学，审计学，管理学等全球99%专业科目。写作团队既有专业英语母语作者，也有海外名校硕博留学生，每位写作老师都拥有过硬的语言能力，专业的学科背景和学术写作经验。我们承诺100%原创，100%专业，100%准时，100%满意。

## MATLAB代写

MATLAB 是一种用于技术计算的高性能语言。它将计算、可视化和编程集成在一个易于使用的环境中，其中问题和解决方案以熟悉的数学符号表示。典型用途包括：数学和计算算法开发建模、仿真和原型制作数据分析、探索和可视化科学和工程图形应用程序开发，包括图形用户界面构建MATLAB 是一个交互式系统，其基本数据元素是一个不需要维度的数组。这使您可以解决许多技术计算问题，尤其是那些具有矩阵和向量公式的问题，而只需用 C 或 Fortran 等标量非交互式语言编写程序所需的时间的一小部分。MATLAB 名称代表矩阵实验室。MATLAB 最初的编写目的是提供对由 LINPACK 和 EISPACK 项目开发的矩阵软件的轻松访问，这两个项目共同代表了矩阵计算软件的最新技术。MATLAB 经过多年的发展，得到了许多用户的投入。在大学环境中，它是数学、工程和科学入门和高级课程的标准教学工具。在工业领域，MATLAB 是高效研究、开发和分析的首选工具。MATLAB 具有一系列称为工具箱的特定于应用程序的解决方案。对于大多数 MATLAB 用户来说非常重要，工具箱允许您学习应用专业技术。工具箱是 MATLAB 函数（M 文件）的综合集合，可扩展 MATLAB 环境以解决特定类别的问题。可用工具箱的领域包括信号处理、控制系统、神经网络、模糊逻辑、小波、仿真等。

## 物理代写|光电技术代写Photovoltaic Technology代考|ELC220

statistics-lab™ 为您的留学生涯保驾护航 在代写光电技术Photovoltaic Technology方面已经树立了自己的口碑, 保证靠谱, 高质且原创的统计Statistics代写服务。我们的专家在代写光电技术Photovoltaic Technology代写方面经验极为丰富，各种代写光电技术Photovoltaic Technology相关的作业也就用不着说。

• Statistical Inference 统计推断
• Statistical Computing 统计计算
• (Generalized) Linear Models 广义线性模型
• Statistical Machine Learning 统计机器学习
• Longitudinal Data Analysis 纵向数据分析
• Foundations of Data Science 数据科学基础

## 物理代写|光电技术代写Photovoltaic Technology代考|Module Configuration

Module inverter is also known as micro-inverter. In contrast to centralized configuration, each micro-inverter is attached to a single PV module, as shown in Fig. 1a. Because of the “one PV module one inverter concept,” the mismatch loss between the PV modules is completely eliminated, leading to higher energy yields. With module configuration, expansion and installation become an easy task. Micro-inverter certainly allows for a very high degree of flexibility, but it comes at an expense of higher upfront costs and greater service requirements. A large number of inverters are required for large-scale application. DC-DC converter is usually included in micro-inverter to boost the low voltage of the PV module to meet the grid requirement. High voltage amplification may shrink overall efficiency and increase price per watt. Although micro-inverters are typically used in low-power application, large-scale PV plant with micro-inverters is emerging. As shown in Fig. 5, Enphase (ENPH) installed a $2 \mathrm{MW}$ solar project at Ontario, Canada’s Vine Fresh Produce, with 9000 Enphase ${ }^{\circledR}$ M215 micro-inverters [12].
Micro-inverters usually come with longer warranty up to 25 years, thanks to their effort to extend the lifespan of the capacitors. The first approach is to eliminate the use of electrolytic capacitors by Enecsys [13]. Enecsys $240 \mathrm{~W}$ micro-inverters are the first micro-inverters without electrolytic capacitors to achieve higher reliability. The micro-inverter configuration is shown in Fig. 6, which includes a DC$\mathrm{DC}$ boost converter and a $\mathrm{DC}-\mathrm{AC}$ inverter (universal converter). The $\mathrm{DC}-\mathrm{DC}$ converter is made up of a resonant $\mathrm{H}$-bridge, a high-frequency (HF) transformer, and a bridge rectifier. With buck, boost and buck-boost capability, the universal converter can operate with a wide range of input voltage, improving the power quality and the efficiency [10]. Without the use of electrolytic capacitors, the inverter has an operating life expectancy of greater than 25 years, matching that of solar PV modules. The second approach is the use of interleaved flyback converter. The Enphase micro-inverter configuration is shown in Fig. 7 [14]. The flyback converter is connected in parallel, and modulated with interleaved PWM. Compared with the conventional flyback converter, interleaved topology requires smaller filter capacitors and smaller HF transformer, which offers higher power capability with greater life expectancy.

## 物理代写|光电技术代写Photovoltaic Technology代考|String Configuration

In string configuration, each inverter is attached to only one PV string, avoiding the use of blocking diode as shown in Fig. 1b. String inverter combines the advantages of simple structure central inverter and high-energy-yield micro-inverter. Higher energy yield is achieved with MPPT operating at string level, thereby reducing the mismatch loss between the PV modules as compared to centralized configuration. Since the configuration is made up of one PV string per inverter, the string inverter is usually designed for low power application, typically for residential rooftop application.

In the past, U.S. regulations dictated that all electrical systems must be grounded. For grounded PV system, galvanic isolation must be provided in order to avoid the leakage current. Galvanic isolation can be provided via HF transformer on the DC side or via LF transformer on the $\mathrm{AC}$ side as shown in Fig. 8 [15]. Besides isolation, transformer steps up the inpul voltage, which provides a wide range of input voltage. However, the transformer is bulky, heavy, and expensive. Even though significant size and weight reduction can be achieved with HF transformer, the use of transformer still reduces the efficiency of the entire PV system.

Since 2005, the National Electric Code update for allowing ungrounded system opens a huge market for transformerless technology. There are numerous types of string inverters available in the market, and only several will be covered here as shown in Fig. 9. The simplest transformerless string inverter is the full-bridge topology as shown in Fig. 9a. The full-bridge topology is modulated by bipolar PWM in order to generate constant CMV, to eliminate the leakage current. Nonetheless, the two-level bipolar PWM doubles the voltage stress and current ripples across the filter inductors, reducing the efficiency of the PV system.

To achieve high efficiency, various inverter manufacturers have developed different circuit configuration with three-level unipolar PWM. The Sunway HERIC topology (Fig. 9b) [16] and the SMA H5 topology (Fig. 9c) [17] introduce DC decoupling and $\mathrm{AC}$ decoupling methods, respectively, to disconnect the PV string from the grid. The former provides lower conduction loss due to reduced semiconductors in the conduction path. However, galvanic isolation alone cannot completely eliminate the leakage current due to the influence of switches’ junction capacitances and parasitic parameters. Therefore, CMV clamping method is proposed in the H6 topology by Ingeteam [18] to completely eliminate the leakage current as shown in Fig. 9c. Two clamping diodes are added in additional to the DC decoupling switches to completely clamp the freewheeling path to half of the input voltage, $V_{\mathrm{DC}} / 2$

## 物理代写|光电技术代写光伏技术代考|字符串配置

. String Configuration .物理代写|光电技术代写光伏技术代考|

## 有限元方法代写

tatistics-lab作为专业的留学生服务机构，多年来已为美国、英国、加拿大、澳洲等留学热门地的学生提供专业的学术服务，包括但不限于Essay代写，Assignment代写，Dissertation代写，Report代写，小组作业代写，Proposal代写，Paper代写，Presentation代写，计算机作业代写，论文修改和润色，网课代做，exam代考等等。写作范围涵盖高中，本科，研究生等海外留学全阶段，辐射金融，经济学，会计学，审计学，管理学等全球99%专业科目。写作团队既有专业英语母语作者，也有海外名校硕博留学生，每位写作老师都拥有过硬的语言能力，专业的学科背景和学术写作经验。我们承诺100%原创，100%专业，100%准时，100%满意。

## MATLAB代写

MATLAB 是一种用于技术计算的高性能语言。它将计算、可视化和编程集成在一个易于使用的环境中，其中问题和解决方案以熟悉的数学符号表示。典型用途包括：数学和计算算法开发建模、仿真和原型制作数据分析、探索和可视化科学和工程图形应用程序开发，包括图形用户界面构建MATLAB 是一个交互式系统，其基本数据元素是一个不需要维度的数组。这使您可以解决许多技术计算问题，尤其是那些具有矩阵和向量公式的问题，而只需用 C 或 Fortran 等标量非交互式语言编写程序所需的时间的一小部分。MATLAB 名称代表矩阵实验室。MATLAB 最初的编写目的是提供对由 LINPACK 和 EISPACK 项目开发的矩阵软件的轻松访问，这两个项目共同代表了矩阵计算软件的最新技术。MATLAB 经过多年的发展，得到了许多用户的投入。在大学环境中，它是数学、工程和科学入门和高级课程的标准教学工具。在工业领域，MATLAB 是高效研究、开发和分析的首选工具。MATLAB 具有一系列称为工具箱的特定于应用程序的解决方案。对于大多数 MATLAB 用户来说非常重要，工具箱允许您学习应用专业技术。工具箱是 MATLAB 函数（M 文件）的综合集合，可扩展 MATLAB 环境以解决特定类别的问题。可用工具箱的领域包括信号处理、控制系统、神经网络、模糊逻辑、小波、仿真等。

## 物理代写|光电技术代写Photovoltaic Technology代考|ECE6456

statistics-lab™ 为您的留学生涯保驾护航 在代写光电技术Photovoltaic Technology方面已经树立了自己的口碑, 保证靠谱, 高质且原创的统计Statistics代写服务。我们的专家在代写光电技术Photovoltaic Technology代写方面经验极为丰富，各种代写光电技术Photovoltaic Technology相关的作业也就用不着说。

• Statistical Inference 统计推断
• Statistical Computing 统计计算
• (Generalized) Linear Models 广义线性模型
• Statistical Machine Learning 统计机器学习
• Longitudinal Data Analysis 纵向数据分析
• Foundations of Data Science 数据科学基础

## 物理代写|光电技术代写Photovoltaic Technology代考|Organization of the Book

For grid integration of PV system, either compact high-frequency transformer or bulky low frequency transformer is employed in the dc- or ac-side of the PV inverter, respectively, to step up the low output voltage of the PV modules to the grid voltage. Galvanic isolation is provided and the safety is assured with the use of transformer. Because of the high cost and significant loss of the transformer, the PV inverter becomes expensive and poor efficient. To mitigate these problems, the transformer is removed from the PV inverter. The transformerless PV inverter is smaller, cheaper, and higher in efficiency. Various transformerless PV inverter topologies, with different circuit configuration and modulation techniques, have been developed recently. The operating principle and the converter structure are evaluated in Chap. 2. It is expected that the transformerless PV inverter would have great potential for future renewable generation and smart micro grid applications.
Tracking the maximum power of the PV arrays at real time is very important to increase the whole system performance. In the past decades, there are a large number of maximum power point tracking (MPPT) methods have been proposed for PV system, such as constant-voltage tracing method (CVT), perturbation, and observation method (P\&O), incremental conductance method (INC), curve fitting method, look-up table method, and so on. Actually, these conventional methods can track the MPP. But these methods have some drawbacks, like oscillation, miscalculation, poor accuracy, unimodal $P-U$ curves only. To overcome the limitation of these methods, some advanced MPPT methods are introduced in Chap. 3. In Chap. 4, the criteria for assessing the performance of MPPT methods are defined followed by a complete description and discussion of both techniques designed for uniform environmental conditions and those designed for nonuniform environmental conditions.

Most of the conventional MPPT algorithms are incapable to detect global peak power point with the presence of several local peaks. A hybrid particle swarm optimization and artificial neural network (PSO-ANN) algorithm is proposed in Chap. 5 to detect the global peak power. The performance of the proposed algorithm is compared with that of the standard PSO algorithm. The proposed algorithm is tested and verified by hardware experiment. The simulation and the experimental results are compared and discussed in the Chapter.

## 物理代写|光电技术代写Photovoltaic Technology代考|Centralized Configuration

When a large number of PV modules are interfaced with a single three-phase inverter as shown in Fig. 1d, this configuration is termed as central inverter. The PV modules are connected into series (called strings) to achieve sufficiently high voltage. These PV strings are then made parallel (called arrays) to reach high power level. A blocking diode is connected in series with each PV string branch to avoid reverse current. Central inverter is widely installed in large-scale PV plant. Because of the centralized configuration (with single set of sensors, control platform, and monitoring unit), the central inverter becomes cost-effective for large-scale application. However, the simple configuration comes at a cost of high-level mismatch loss between the PV modules owing to the utilization of a common maximum power point tracking (MPPT) for the entire PV arrays. The power generation loss becomes apparent during the inverter outages. The expansion of the power plant is also difficult to be realized at centralized level.

The conventional central inverter topology is a two-level three-phase full-bridge converter, as indicated in Fig. 2. It is called two-level because it can apply only two voltage levels: the DC supply voltage and the reverse of that voltage. The two-level inverter consists of DC-link capacitors, full-bridge inverter (6 IGBTs) and filters. The central inverter is connected to medium voltage network via a transformer to step up the voltage from LV (e.g., $400 \mathrm{~V}$ ) to MV level (e.g., $11 \mathrm{kV}$ ). To meet higher power requirement, the PV inverter industry, such as ABB PVS800 central inverter [9], introduces a parallel connection directly to the $\mathrm{AC}$ side, enabling power to be fed to the medium voltage network via a single transformer as illustrated in Fig. 3. This avoids the need of individual transformer for each central inverter, reducing the cost and space. Nevertheless, in systems where the DC side needs to he grounded, a separate transformer must he employed for galvanic isolation.

The demand of higher power central inverter (MW range) has been continuously increasing with the emerging large-scale PV plant. Although advanced semiconductors with higher nominal voltage and current capability are available, they are very relatively more expensive with high loss. On the other hand, the high-power central inverter is made possible with multilevel configuration. Because of its reduced voltage derivatives $(\mathrm{d} v / \mathrm{d} t)$ and higher voltage operating capability, the multilevel converter becomes attractive for high power application. The multilevel converter generates increased level at output phase voltage, which leads to higher power quality and reduced switching loss. Nonetheless, the high power quality requires higher complexity of circuit configuration and the corresponding control, which leads to higher initial cost. The three-phase three-level neutral point clamped (3L-NPC) converter and the T-type (3L-T) converter are two widely used converter as shown in Fig. 4 [10]. The NPC and T-type converter modules have been commercialized by several manufacturers such as Semikron, Infineon and Fuji [11].

## 有限元方法代写

tatistics-lab作为专业的留学生服务机构，多年来已为美国、英国、加拿大、澳洲等留学热门地的学生提供专业的学术服务，包括但不限于Essay代写，Assignment代写，Dissertation代写，Report代写，小组作业代写，Proposal代写，Paper代写，Presentation代写，计算机作业代写，论文修改和润色，网课代做，exam代考等等。写作范围涵盖高中，本科，研究生等海外留学全阶段，辐射金融，经济学，会计学，审计学，管理学等全球99%专业科目。写作团队既有专业英语母语作者，也有海外名校硕博留学生，每位写作老师都拥有过硬的语言能力，专业的学科背景和学术写作经验。我们承诺100%原创，100%专业，100%准时，100%满意。

## MATLAB代写

MATLAB 是一种用于技术计算的高性能语言。它将计算、可视化和编程集成在一个易于使用的环境中，其中问题和解决方案以熟悉的数学符号表示。典型用途包括：数学和计算算法开发建模、仿真和原型制作数据分析、探索和可视化科学和工程图形应用程序开发，包括图形用户界面构建MATLAB 是一个交互式系统，其基本数据元素是一个不需要维度的数组。这使您可以解决许多技术计算问题，尤其是那些具有矩阵和向量公式的问题，而只需用 C 或 Fortran 等标量非交互式语言编写程序所需的时间的一小部分。MATLAB 名称代表矩阵实验室。MATLAB 最初的编写目的是提供对由 LINPACK 和 EISPACK 项目开发的矩阵软件的轻松访问，这两个项目共同代表了矩阵计算软件的最新技术。MATLAB 经过多年的发展，得到了许多用户的投入。在大学环境中，它是数学、工程和科学入门和高级课程的标准教学工具。在工业领域，MATLAB 是高效研究、开发和分析的首选工具。MATLAB 具有一系列称为工具箱的特定于应用程序的解决方案。对于大多数 MATLAB 用户来说非常重要，工具箱允许您学习应用专业技术。工具箱是 MATLAB 函数（M 文件）的综合集合，可扩展 MATLAB 环境以解决特定类别的问题。可用工具箱的领域包括信号处理、控制系统、神经网络、模糊逻辑、小波、仿真等。