Outline
- Abstract
- Keywords
- 1. Introduction
- 2. Structure Topologies for Grid-Connected Photovoltaic Systems
- 2.1. Central Inverters
- 2.2. String Inverters
- 2.3. Multi-String Inverters
- 2.4. Ac Modules
- 3. Impact of Inverter Configuration on Energy Cost of Grid-Connected Photovoltaic Systems
- 4. Control Structures for Grid-Connected Photovoltaic Systems
- 4.1. Control Structure for Single Phase with Dc–dc Converter
- 4.1.1. Mppt Control
- 4.1.2. Dc–dc Boost Converter Control
- 4.2. Control Structure for Single Phase Without Dc–dc Converter
- 5. Reactive Power Requirements
- 6. Control Based on the Shifting Phase for Grid Connected Photovoltaic Inverter
- 7. Control Structure for Three-Phase Inverter Connected to the Grid
- 7.1. Dq Control
- 7.2. αβ–control
- 7.3. Abc Control
- 8. Conclusion
- References
رئوس مطالب
- چکیده
- کلیدواژه ها
- 1. مقدمه
- 2. توپولوژی های ساختار مخصوص سیستم های فتوولتائیک متصل به شبکه
- 2.1. اینورترهای مرکزی
- 2.2. اینورتر رشته ای
- 2.3. اینورترهای چند رشته ای
- 2.4. ماژول های AC
- 3. تاثیر پیکربندی اینورتر بر هزینه انرژی سیستم های فتوولتائیک متصل به شبکه
- 4. ساختارهای کنترل مخصوص سیستم های فتوولتائیک متصل به شبکه
- 4.1. ساختار کنترل مخصوص تک فاز با مبدل DC- DC
- 4.1.1. کنترل MPPT
- 4.1.2. کنترل مبدل ارتقاء یا بوست DC- DC
- 4.2. ساختار کنترل مخصوص تک فاز بدون مبدل DC- DC
- 5. الزامات مورد نیاز قدرت واکنشی
- 6. کنترل مبتنی بر تغییر فاز برای اینورتر فتوولتائیک متصل به شبکه
- 7. ساختار کنترل مخصوص اینورتر سه فازه متصل به شبکه
- 7.1. کنترل dq
- 7.2. کنترل- αβ
- 7.3. کنترل abc
- 8. نتیجه گیری
Abstract
In grid-connected photovoltaic systems, a key consideration in the design and operation of inverters is how to achieve high efficiency with power output for different power configurations. The requirements for inverter connection include: maximum power point, high efficiency, control power injected into the grid, and low total harmonic distortion of the currents injected into the grid. Consequently, the performance of the inverters connected to the grid depends largely on the control strategy applied. This paper gives an overview of power inverter topologies and control structures for grid connected photovoltaic systems. In the first section, various configurations for grid connected photovoltaic systems and power inverter topologies are described. The following sections report, investigate and present control structures for single phase and three phase inverters. Some solutions to control the power injected into the grid and functional structures of each configuration are proposed.
Keywords: Control - Grid connected photovoltaic system - Inverters - Power conditioningConclusions
This paper has presented different topologies of power inverter for grid connected photovoltaic systems. Centralized inverters interface a large number of PV modules to the grid. This included many shortcomings due to the emergence of string inverters, where each single string of PV modules is connected to the DC–AC inverter. The multi-string inverter is the development of the string inverter, where several strings are interfaced with their individual DC–DC converter (separate) MPPT tracking systems) to a common DC–AC inverter. Another trend seen is the development of the ac module, where each PV module is interfaced to the grid with its own DC–AC inverter.
The efficiency characteristic of parallel inverters with a common DC bus is deliberated along with the optimal operation strategy. Inverter system performance ratio (ISPR) is proposed as an overall index of lifetime energy conversion efficiency. It shows that the configuration with a common DC bus is a potential solution to reduce the energy cost of PV power generation systems A discussion of the different controllers and their ability to compensate for low-order harmonics presented in the grid was given. The PRþHC controller gives a better dynamic response of the system, very low harmonic distortion and eliminates the error in the steady state without using the feed-forward voltage. Adding the harmonic compensator (HC) to the resonant proportional controller (PR) makes the system more reliable with better elimination of harmonics. (Fig. 18).
Power factor control and reactive power regulation is known as the most important issue in connecting PV array to the grid, the control based on the Shifting Phase for Grid Connected Photovoltaic Inverter allows the control in a fast and simple way in case that not only an active power needs to be injected but also a reactive one.
Some Implementation structures for three phase inverters, like dq, αβ and abc control were reported. The PI controller is widely used in conjunction with the dq control. The implementation of PR controller in αβ is commonly used. In the abc control, nonlinear controllers like hysteresis or dead beat are preferred due to their high dynamics.