DC-link protection for grid-connected photovoltaic system: a review

As the economic growth and population increase, the demand on energy supply has also increases. The disadvantages that energy production based on non-renewable energy sources bring to the environment has stimulate the idea of producing a clean and sustainable power in huge quantities from renewable energy sources such as solar and wind energy. In recent years, photovoltaic (PV) systems are mostly used due to its light and easy-installable characteristics. It has two approaches which are stand-alone PV system (off-grid) and grid-connected PV system. Although it is said to be the most promising renewable energy, it could not avoid from disturbance. In grid-connected PV system, faults could occur on the grid side, leading to the increase in DC-link voltage and overshoot grid current. These situations could stress electrical components and decrease power quality of the system. Therefore, many protection schemes have been introduced to overcome this matter. In this paper, the development of grid-connected PV system was expressed and the impacts of grid faults on were discussed. Several conventional protection schemes implemented in the grid-connected PV system were reviewed. In the end, this paper proposed a new protection scheme which namely zero protection scheme that has the same function to limit the overshoot in DC-link voltage

Performance analysis on grid-connected pv system during grid faults with dc-link protection and decoupled current control

The advancement of technology and the increase in population have increased the demand for electrical supply as well. The drawbacks of electrical generating from nonrenewable energy to the environment have encouraged the researchers to produce clean and sustained power in vast quantities from sustainable energy. Recently, PV systems are frequently used owing to its light and easy-to-install characteristics. Although it was proven auspicious, faults can happen on the grid side of a grid-connected PV system, causing overshoot DC voltage and overcurrent. Thus, stressing the electrical component, lessening the system’s power quality and inverter’s trip. Therefore, many FRT strategies have been introduced to overcome these issues. This thesis proposed a new approach to alleviate this matter by controlling zero switching state of NPC inverter while injecting reactive current to the grid. First, the development of a two-stage grid-connected PV system was stated and the effects of grid faults were deliberated. Some conventional FRT strategies employed in the grid-connected PV system were studied. Furthermore, the efficiency of the scheme was verified by comparing it with a conventional method using DC chopper. The results showed the proposed method could lessen the overshoot DC voltage and injecting reactive current to the grid. Also, the results shown were similar to those of the conventional method

A REVIEW OF BURDEN OF CAREGIVERS OF PATIENTS WITH ALZHEIMER'S DISEASE

Many are still unaware of the fact that Alzheimer’s disease (AD) also affects the caregivers quite significantly. Caregivers refer to people who are accountable of taking care of AD patients which provide helps with his or her daily living activities and may become a full-time commitment for the caregiver. This gives rise to a concept called caregiver burden. As these caregivers spend most of their time taking care of AD patients, most of them suffer psychologically as well as physically. Unfortunately, the risk of mental and physical impairment among the caregivers of Alzheimer’s patient may cause poor quality of life to both the patients and their caregivers. In addition, due to their role and responsibilities as a caretaker, they often do not have the opportunity to seek help and advices. This review article was conducted by sieving through numerous literature and studies regarding the challenges and how to help the burden of the caregivers of Alzheimer’s patients . This paper aims to give and overview, suggestions as well as to increase the awareness of the caregiver’s burden