臺灣博碩士論文加值系統

中文摘要
本論文以數位訊號處理器(DSP)作為控制核心並加入國際法規和併網規範要求的保護功能，設計一3000瓦的市電併聯型太陽光電換流器。
在本論文中，首先我們介紹市電併聯型太陽光電換流器系統方塊圖的設計，而在系統介面說明如何採用數位信號處理器(DSP)TMS320F2808來達到系統控制。第二、在硬體設計中設計換流器功率級電路架構，並且配合零交越偵測電路，使得輸出電流可以和市電電源同步，除此之外我們依據VDE-AR-N 4105的安全性要求，設計並實現其功能，如繼電器失效偵測、絕緣阻抗偵測(RISO)和殘餘電流偵測(RCMU)。第三、增加數位訊號處理器(DSP)的軟體設計，其中包含閉迴路系統控制設計、改良型擾動觀查法的最大功率追蹤控制，市電電壓和市電頻率的偵測、孤島效應保護偵測、繼電器失效偵測、絕緣阻抗偵測、殘餘電流偵測。
最後我們實驗製作一3000瓦太陽光電市電併聯型換流器，經實驗室完成一硬體雛型並驗証其功能，實驗結果証明其可達到預期效果。
本文主要貢獻如下:
(1) 換流器導入可符合目前最新的安規認証標準IEC62109和德國低電壓併網規範VDE-AR-N 4105的要求，使其具有系統安全性供使用者應用。
(2) 採用改良型擾動觀查法來控制，達到快速最大功率追蹤的功能。
(3) 發明了繼電器失效偵測，不僅可提供換流器更安全的防護機制且達到簡化電路，進而提高產品之競爭優勢及可靠度。

Abstract
In the thesis, we use digital signal processor (DSP) as the control core and build the protection feature of international regulations and grid-connected regulations to design a grid-connected 3000 watt photovoltaic (PV) inverter.
First, we introduce the grid-connected photovoltaic (PV) inverter block diagram and explain all functions on the digital signal processor (DSP) TSM320F2808 control system to achieve a system configuration and interface. Secondly, we introduce a photovoltaic (PV) inverter power stage structure, and combine zero crossing detection with AC synchronization in the hardware design. In addition, the functional safety functionality is implemented according to the requirements of VDE-AR-N 4105, such as relay defect detection, insulation resistance (RISO) measurement and residual current monitoring unit detection (RCMU). Third, design the digital signal processor (DSP) software control algorithm of this system; we introduce each function of close loop system control, voltage monitoring, frequency monitoring, insulation detection, residual current monitoring unit detection, improved maximum power point tracking (MPPT) algorithm and anti-islanding protection algorithm.
Finally, we complete a prototype of 3000watt photovoltaic (PV) inverter and implement to assess the predictions. The experimental results are in feasibility close to the estimation.
The contributions of our research are as follows:
(1) Import an IEC62109 and VDE-AR-N 4105 specifications requirements that has system security.
(2) Improve perturbation and observation (P&O) control to reach the maximum power point quick tracking.
(3) Invent a new detect unit with relay, provide more security protection of this mechanism and simplify some circuits on inverter system. Thereby, optimize about cost and reliability.

Contents

中文摘要…………………………………………………………………...I

Abstract………………………………………………………………..…………..II

誌謝………………………………………………………………………….........III

Contents………………………………………………………………………....IV

List of Figures………………………………………………………….….......VI

List of Tables……………………………………………………………………IX

Chapter 1 Introduction…………………..………………………………………1

1-1 Research Motivations and Objectives…………………………………..1

1-2 Purpose of the Study……………………………………………………4

1-3 Organization of this Thesis……………………………………………..5

Chapter 2 Introduction to Photovoltaic Power System………………………….6

2-1 Types of PV System…………………………………………………….6

2-2 Single Phase Grid Connected Inverter Topology……………………....9

2-3 Maximum Power Point Tracking……………………………………...12

2-4 Anti-Islanding Protection……………………………………………...19

2-5 Product Certification Regulations……………………………………..21

Chapter 3 Design of a DSP Based Grid-Connected PV Inverter……………….23

3-1 System Configuration and Interface…………………………………...23

3-2 Hardware Design………………………………………………………24

3-3 DSP Control Algorithm Design………………………………………..34

Chapter 4 System Assembly and Experimental Verification…………………..43

4-1 System Assemble………………………………………………………43

4-2 Experimental Results…………………………………………………..44

Chapter 5 Conclusions and Future Research…………………………………...61

5-1 Conclusions……………………………………………………………61

5-2 Future Research………………………………………………………..61

References………………………………………………………………………63


List of Figures

Figure 1-1 The distributions of traditional energy and renewable energy.…….1
Figure 1-2 Structure chart of electrical power generating system..………….....2
Figure 1-3 Contrast of cost during 2008-2030…..…………………………......3
Figure 1-4 PV Inverter block diagram…………………………………………4
Figure 2-1 The composition of solar system……………..…………………….6
Figure 2-2 Stand-alone system…………………………...…………………….7
Figure 2-3 Grid-connected system……………………………………………..8
Figure 2-4 Hybrid system………………………………………………………8
Figure 2-5 Centralized inverter…………………………………………………9
Figure 2-6 String inverter……………………………………………………..10
Figure 2-7 Multi-string inverter………………………………………………10
Figure 2-8 Single-panel module inverter……………………………………..10
Figure 2-9 Classification of grid-connected solar photovoltaic inverter circuit framework …………………………………………………………………... ...11
Figure 2-10 Single-phase non-isolated grid-connected inverter……………….11
Figure 2-11 Voltage-power characteristic curve of solar energy panel in different illuminations………..……………………………………….…………...…..…12
Figure 2-12 Voltage-power characteristic curve of solar energy panel in different temperatures………...………………………………………...………………...13
Figure 2-13 Block of Perturb and Observe…………………………………….14
Figure 2-14 Flowchat of Perturb and Observe…………………………………14
Figure 2-15 Block of Incremental conductance………………………………..16
Figure 2-16 Flowchart of Incremental conductance……………………………16
Figure 2-17 Flowchart of the three-point weight comparison…………………18
Figure 2-18 Possible states of the three perturbation points…………………...19
Figure 2-19 Islanding Effect Schematic Diagram………………………….......20

Figure 3-1 PV inverter system configuration and interface diagram…………..23
Figure 3-2 Two stage power schema circuit diagram………………………….25
Figure 3-3 Zero crossing detection diagram…………………………………...26
Figure 3-4 Zero crossing detection circuit diagram……………………………26
Figure 3-5 Drive circuit diagram………………………………………………27
Figure 3-6 Relay defect circuit diagram……………………………………….28
Figure 3-7 (a) Fire wire (Line) short circuit diagram………………………….29
Figure 3-7 (b) Schematic waveform diagram………………………………….30
Figure 3-8 (a) Neutral line short circuit diagram……………………………....30
Figure 3-8 (b) Schematic waveform diagram………………………………….31
Figure 3-9 Insulation resistance detection design chart………………………..32
Figure 3-10 Residual current monitoring unit detection……………………….33
Figure 3-11 Close loop control of boost converter……………………………..34
Figure 3-12 Close loop control of Full-bridge inverter………………………...35
Figure 3-13 Close loop system control flowchart (main)…………………...….36
Figure 3-14 Close loop system control flowchart (subroutines)……………….37
Figure 3-15 Voltage monitoring flowchart……………………………………..38
Figure 3-16 Frequency monitoring flowchart…………………………………..39
Figure 3-17 Insulation resistance detection flowchart………………………….40
Figure 3-18 Residual current monitoring unit detection flowchart…………….41
Figure 3-19 Improved maximum power point tracking flowchart……………..42
Figure 4-1 Picture of grid-connected PV inverter……………………………...43
Figure 4-2 Layout of test instrument…………………………………………...45
Figure 4-3 Curve table of efficiency and power ……………………………….46
Figure 4-4 Waveform of inverter’s input side voltage, current, power and DC link voltage……………………………………………………………………..47
Figure 4-5 AC voltage, current waveforms after the converter is paralleled with grid-connect power……………………………………………………………..47
Figure 4-6 Measurement waveform of under voltage protection………………48
Figure 4-7 Measurement waveform of over voltage protection………………..49
Figure 4-8 Measurement waveform of under frequency protection……………50
Figure 4-9 Measurement waveform of over frequency protection……………..50
Figure 4-10 Schematic diagram of measurement………………………………51
Figure 4-11 Fire wire (L) short measurement waveform……………………….52
Figure 4-12 Neutral (N) short measurement waveform………………………...52
Figure 4-13 Schematic diagram of measurement………………………………53
Figure 4-14 Comparison chart of input voltage on the reading value of digital signal processor and input voltage on insulation resistance value……………..54
Figure 4-15 Schematic diagram of measurement………………………………55
Figure 4-16 Measurement waveform of steady state fault current……………..55
Figure 4-17 Measurement waveform of transient fault current………………...55
Figure 4-18 Measured waveform of instantly added 30mA fault current……..56
Figure 4-19 Measured waveform of instantly added 60mA fault current……..56
Figure 4-20 Measured waveform of instantly added 150mA fault current……56
Figure 4-21 Schematic diagram of measurement………………………………58
Figure 4-22 Output power 25%, RLC load-1%...................................................59
Figure 4-23 Output power 50%, RLC load -4%..................................................59
Figure 4-24 Output power 100%, RLC load +2%...............................................60


List of Tables

Table 2-1 Character comparison table of passive and active detection methods…………………………………………………………………………21
Table 2-2 Relevant international regulations for solar energy inverter ………..22
Table 3-1 Driver signal correspondence relay defect relationship table……….29
Table 4-1 Main parts’ parameters of power stage circuits ...…………………..44
Table 4-2 Efficiency measurement table……………………………………….45
Table 4-3 Protection point and trip time table …………………………………49
Table 4-4 Comparison chart of input voltage, reading value of digital signal processor and insulation resistance value………………………………………53
Table 4-5 Test result of anti-Islanding detection protection…………………..58

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