Provisiones y pasivos contingentes

From Figure G-3, it can be seen clearly that the lighting, computer and motor waveforms do not have a perfect waveforms. Those waveforms have sag voltages and currents between 0.4 to 0.6sec. Although the sag values are acceptable in the design, it is much better if perfect load waveforms can be obtained. Therefore, in order to improve these waveforms, the feedback loop control needs to be improvised.

The grid is a tremendous resource. A grid-connected PV system will be more efficient, arguably greener, and certainly cheaper by designing the model without batteries. This is because batteries contain and emit toxic chemicals and wear out over time. Therefore designing the system with other source of storage instead of batteries as back up can make further investigation. The systems can also be designed to produce at their "maximum power curve” rather than the lower voltage needed to recharge batteries.

CHAPTER 8

CONCLUSION

Utility-interactive PV power systems mounted on residences and commercial buildings are likely to become a small, but important source of electric generation in the next century. As most of the electric power supply in developed countries is via centralised electric grid, it is certain that widespread use of photovoltaic will be as distributed power generation interconnected with these grids. This is a new concept in utility power production, a change from large-scale central examination of many existing standards and practices to enable the technology to develop and emerge into the marketplace. As prices drop, on-grid applications will become increasingly feasible. For the currently developed world, the future is grid-connected renewables.

Grid-connected PV system is becoming more realistic all the time. Modern electronic controls make it easy to tie power produced on homes and other buildings into the grid. They even make sure juice does not feed back to the grid during blackouts, so linemen are not electrocuted. The policy innovation of net metering, now in effect in around half the states, credits on-site power producers when they ship their excess back into the grid. This represents a powerful incentive for home and business PV installations.

The simulation results have shown that the efficiency of the grid-connected PV system can withstand as many loads. At times of grid failures, the battery will supply the loads. Experience has shown that conventional systems are often not flexible enough to response to changing load demand and varying operating conditions.

Commercial grid power quality has played an important role to ensure that the smooth operation of sensitive and critical equipment has been achieved. It is also important to realize that many critical non-linear loads are sensitive to incoming line-transients and input harmonic voltage distortion.

During this project, the overall simulation results of the grid-connected PV system were carried out to the best ability possible, with the use of the computer software package PSCAD/EMTDC. The results were previously discussed in Chapter 5, where an explanation was given for the control blocks used in the simulation of the grid-connected PV circuits.

Overall, the project gave understanding and knowledge of how uninterruptible power supplies operate when grid failure occurs within the system. Future students initiating the control and simulation of the grid-connected PV can approach further analysis.

CHAPTER 9

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Appendix

A