Improving Power Quality with Solar and Storage
More and more commercial and industrial businesses are investing in solar energy systems to power their facilities. Fueled by renewable energy, these systems can lower your tax bill and operating costs, and essentially lock in electricity costs for 25+ years while you help protect the environment for future generations. They increase the value of your facility and appeal to current and potential customers. Furthermore, with significant advances made in inverter and storage technologies, nagging power quality issues that have historically plagued industrial and commercial operations can also be addressed.
As electronic equipment used in industrial and commercial operations have become increasingly complex, power quality issues resulting from grid supplied power have intensified in scale and impact. Since resolving ongoing power quality issues does not normally fall within the expertise of the average facility operations and maintenance staff, most of the events cause plant downtime, reduced capacity, production waste, and premature equipment failure. Without an effective solution, these problems can result in significant financial impacts on the overall business.
Typical power quality events fall into four categories:
Voltage Sags and Swells: Nominal voltage is the designated voltage provided by the electric utility or the voltage provided by a transformer within your facility. A voltage sag occurs when voltage on the electrical distribution network falls below nominal voltage for multiple cycles; a swell is the opposite and occurs when voltage exceeds nominal voltage over multiple cycles. Although voltage sags and swells can be caused by either internal or external forces, they can lead to severe impacts for your facility including complete operational shut down.
Transients: One of the most damaging voltage disturbances is a transient (or spike). Like a swell, a transient is a condition in which the voltage on the electrical system is higher than the expected voltage. The distinguishing characteristic of a transient is the duration, which is typically within a cycle, or less than 1/60th of a second. The source of a transients can be either internal or external to your facility, and they have the potential to damage equipment with power supplies especially computers, instrumentation, and control devices. Over time, repeated transients will cause equipment to fail prematurely.
Harmonics: Harmonics (aka noisy/dirty electricity) are distortions to voltage and current sine waves. If equipment in an industrial facility operates by alternating between AC and DC, harmonic distortion will likely result. Examples of such equipment include variable speed drives, furnaces, light ballasts, and DC power supplies in computers or other electronic equipment. According to the IEEE 1159 standard, voltage harmonic distortion should be kept under 4% to avoid problems with extremely sensitive equipment like lighting and computers. Harmonic distortion more than 4% can lead to a higher probability of downtime, erratic equipment operation, nuisance tripping, increased heat in conductors and motor windings, and reduced power capacity.
Power Factor: In AC circuits, the power factor is the ratio of the real power that is used to do work and apparent power that is supplied to the circuit. The power factor can range in value from 0 to 1, with 1 being the ideal. When you have low power factor, you are not fully leveraging the electrical power being paid for. Lower power factor can result from equipment such as large fans, motor, presses or high intensity lighting. Like harmonics, it can reduce capacity within your facility and decrease valuable production efficiency.
As the cost of both solar and energy storage technologies have drastically declined over the last decade, these technologies can now be combined to economically improve power quality challenges common in industrial and commercial settings. Uninterruptible power storage resources have been used for quite some time to manage power quality events, but the advent of new features in the solar photovoltaic (PV) inverter technology dramatically improves your arsenal in attacking power quality issues. Advanced features such as volt/VAR control, voltage ride-through (VRT) capability, frequency ride through, real power/frequency control, ramp rate control, and communications can all be leveraged to directly improve power quality. Furthermore, coupling these features with adequate storage capacity allows for islanding to ride out a complete loss of grid voltage or power.
At the heart of these advanced features is the control technology available in modern inverters. The core principle of power quality management is to control and convert electric energy to meet the quality conformance and optimal efficiency requirements of the business operation. The latest active control capabilities, such as an Active Power Filter, not only improve the quality of output voltage and current but can also rapidly draw on storage devices to provide compensating capacity when necessary. The resulting output power feeding the distribution network is far cleaner than that typically supplied from the public grid. Through these capabilities, such a system can be leveraged to directly address all four of the common power quality disturbances.
For safe and dependable industrial and commercial operations, a reliable and steady supply of power must be kept within tight voltage and quality limits. Systems combining solar PV and batteries coupled with a modern grid-tied inverter can deliver the required level of power quality allowing you to do what you do best without interruption.