Transformerless Inverter With Virtual DC Bus Concept for Cost-Effective Grid-Connected PV Power Systems

Direct-current (DC) motor is a commonly used motor; its speed is directly affected by applying mechanical load. This paper proposes the design of wide speed-load range controller for a direct-current (DC) shunt motor based on proportional–integral–derivative (PID controller) with genetic system for controller parameters adjusting. The genetic based PID controller is simulated by using Matlab software package and tested with different sudden load values and different working speeds. A present control loop contains the suggested PID controller also Pulse-Width-Modulation PWM generator and H-bridge inverter. With the genetic system enhancement to parameters of developed PID controller, the results demonstration that this controller has great impact to preserve the profiles of the motor speed and produced torque after applied sudden load, and its intensification the motor performance at different speed and load conditions.

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Numerous speeds-loads controller for DC-shunt motor based on PID controller with on-line parameters tuning supported by genetic algorithm

当前来源的连接格子的 inverter 的新奇拓扑学基于 immittance 变换器理论被建议。正弦正弦脉搏宽度调整(PWM ) 的控制策略被学习。与传统的当前来源的 inverter 相比，力量频率电感器和力量频率变压器被高频率电感器和一个高频率变压器代替。因此，建议 inverter 有小体积，低成本，低全部的泛音失真(THD ) ，低功率损耗，高功率因素(PF ) 和简单控制的优点。而且，格子电压不能与接近一个的高 PF 影响连接格子的 inverter 和当前来源的 inverter 的产量电流被认识到。最后，理论分析的有效性和控制计划的可行性被模拟和试验性的结果显示出。

Topology for current-source grid-connected inverter with improved efficiency and pulse width modulation control strategy

One of the most important and common parts of the modern power systems is the grid-connected photovoltaic (PV) systems. Recently, these systems have gotten a big revolution due to the introduction of the transformerless inverters. It has the merits of small size, low cost, and high efficiency. However, transformerless inverters has a general safety problem related to the earth leakage current. Various researches were directed toward evolving their performance and diminishing the leakage current to the standard limits. This article proposes an application of the H7 controller to a PV powered grid-tied three phase transformerless inverter. The transformerless inverter is linked with the grid through a boost converter. The boost converter inductance is rearranged and divided to reduce the earth leakage current of the system. simulations are carried out for the proposed H7 PV grid-tied system and for a system that uses the conventional three phase inverter. The simulation results show that the H7 inverter provides lower leakage current, higher efficiency, and lower total harmonic distortion (THD) compared to the conventional three phase inverter.

https://ijpeds.iaescore.com/index.php/IJPEDS/article/download/21291/13526

H7 three phase transformerless inverter for photovoltaic grid-tied system with maximum power point operation

Grid tied operation is a working scheme of photovoltaic power system operating together with utility power grid to supply electric power to the load. In a grid connected photovoltaic system, the energy management can be applied to optimize energy utilization of photovoltaic system while keeping high reliability of power supply to the power load. Compared to voltage source inverter system, the grid connected photovoltaic system using current source inverter offers some merits such as higher quality of AC current, higher reliability of inverter, and high power factor operation. This paper discusses and analyzes characteristics of DC current component injection in a grid tied photovoltaic system using H-bridge current source inverter and transformer. Some data were presented and discussed to explore the characteristics of DC current injection of a grid connected H-bridge CSI. 

Characteristics of DC current component injection in grid tied H-bridge CSI with transformer

Grid tied photovoltaic (PV) system is an operation mode of PV system working together with utility power supply to provide power to the power load. Conventionally, transformer is used together with the power inverter. The power transformer works as galvanic insolation amongst PV system and power grid. It works also to raise the voltage of power inverter. However, use of transformer will add system complexity, price, weight and size of the entire system. Transformer-less system is an alternative to make the system simpler and more practical in use. The paper discusses performance of transformer-less grid tied PV systems using diode clamped and neutral point shorted inverters. Effects of transformer elimination to the feat of the grid tied PV system especially harmonics content and leakage current of PV system were examined and analyzed. The performance was also compared with the traditional system using H-bridge inverter. The leakage currents did not flow in the system applying diode clamped inverter, and neutral point shorted inverter. In case of harmonics content, the diode clamped inverter injected less harmonics components than the neutral point shorted inverter. The neutral point shorted provides a simpler inverter circuit in the transformerless systems. Normal 0 false false false MS X-NONE X-NONE /* Style Definitions */
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https://ijpeds.iaescore.com/index.php/IJPEDS/article/download/20545/13152

A performance comparison of transformer-less grid tied PV system using diode clamped and neutral point shorted inverters

Research and development on power converters are getting more interesting in recent years. It is also buttressed by rapid development in related fields, such as power semiconductor, digital advanced control, magnetic material and use of power converters in many sectors.  In addition to the power quality matter, simplicity of inverter circuits is another notable aspect that should be considered toward economical feature. Adding the quantity of power switches will increase complexity of overall inverter circuits. This paper discusses a circuit configuration of three-level modified sine wave neutral point shorted power inverter which work converting dc power into ac power with less number of power switches. To improve the performance and feature of inverter circuits, the inverter was equipped with online temperature monitoring, and overheat protection based on internet of things. Adding online temperature monitoring system makes easier in monitoring of circuits to prevent the excessive faults of inverter. Some computer based test data are shown and discussed. Furthermore, experiment results of the inverter prototype, and its online monitoring system are presented. Test outputs demonstrated that the proposed system worked properly generating a three-level modified sine wave voltage, with online temperature monitoring system.

Hari Siswantoro

Papers

A performance comparison of transformer-less grid tied PV system using diode clamped and neutral point shorted inverters

Three-level modified sine wave inverter equipped with online temperature monitoring system