In the realm of modern electrical power systems, the significance of active harmonic filters (AHFs) cannot be overstated. They are the guardians of power quality, ensuring that electrical equipment operates smoothly by effectively counteracting harmonic distortions. When it comes to making a purchase decision for an AHF, a multitude of critical factors demand meticulous attention. In this comprehensive blog post, we will explore each of these aspects in detail and showcase how YT ELECTRIC's AHFs stand out in the market.
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The choice of inverter topology lays the foundation for an AHF's capabilities. The 3-level NPC inverter topology has become the gold standard, outshining the traditional 2-level topology. In a 3-level setup like that employed by YT ELECTRIC's AHFs, the switching frequency and voltage stress are evenly distributed among the IGBTs. This not only prolongs the lifespan of the power electronics but also generates an output waveform that closely approximates a sinusoid. The resulting smaller LC-filter requirement leads to a more compact and space-efficient AHF system. With higher efficiency, lower losses, and reduced noise levels, YT ELECTRIC's 3-level NPC inverter-based AHFs offer a lower total cost of ownership. Our products' performance advantages are clearly demonstrated across various output power levels, as seen in comparative analyses.
Minimizing losses is essential for maximizing the return on investment in AHFs. Typically, AHFs experience losses in the 2 - 3% range depending on the rated power. YT ELECTRIC's AHFs, leveraging advanced design and technology, achieve impressively low losses within this spectrum. By opting for our AHFs with their optimized loss characteristics, businesses can realize substantial financial savings over the long haul, significantly reducing the life cycle cost of their power systems.
In power systems where rapid changes are the norm, a fast response time is non-negotiable. Applications such as welding machines, lifts, and cranes are highly susceptible to fast voltage fluctuations and transients. YT ELECTRIC's AHFs are engineered with rapid response capabilities, ensuring that they can swiftly mitigate such issues. Our state-of-the-art technology enables the AHFs to react in real-time, safeguarding the stability of these critical processes.
Interharmonics, often stemming from synchronization glitches, can lurk in electrical installations. Cyclo converters and certain older wind turbine generators are common sources. YT ELECTRIC's AHFs are designed with sophisticated algorithms to detect and neutralize interharmonics effectively. Unlike some competitors' products, our AHFs don't shy away from this challenge, providing comprehensive protection and maintaining power quality integrity even in the presence of interharmonic sources.
Harmonics can manifest in both odd and even orders. While some AHFs claim to handle up to the 51st harmonic, in practical power systems, those above 50 are rarely significant. YT ELECTRIC's AHFs offer a highly customizable harmonic compensation capacity. You can precisely select the harmonic orders you need to address, whether it's a specific range or the entire spectrum from 1st to 50th (both odd and even). This flexibility ensures that our AHFs can be optimized for any electrical installation, maximizing the effectiveness of harmonic cancellation.
In many countries, strict EMC guidelines are in place. To prevent interference with other electrical equipment, an AHF must be equipped with a properly designed EMC filter. YT ELECTRIC's AHFs come with state-of-the-art EMC filters that are rigorously tested to meet and exceed international standards. This guarantees that our products can operate seamlessly within any electrical environment without causing disruptions or malfunctions in neighboring devices.
Derating according to Harmonic Order: Understanding the True Capability
The rating of an AHF is typically specified at nominal load (50/60Hz). However, as the AHF operates at higher harmonic frequencies, its capacity relative to the nominal rating may derate. For instance, a 50% derating at the 13th harmonic order means that a 100A AHF can only handle 50A of compensation at that frequency. YT ELECTRIC's AHFs are engineered with a high di/dt capacity, which gives them excellent derating performance. Our products maintain their effectiveness across a wide range of harmonic frequencies, ensuring reliable compensation even in challenging electrical scenarios.
AHF suppliers offer various installation options, including cubicle type, wall mount, and loose modules. Cubicles often come with additional features like relays and proper air circulation systems, providing a higher IP rating. YT ELECTRIC's AHFs feature a modular design that allows for easy expansion of the AHF's capacity within the existing configuration. This flexibility enables businesses to adapt to changing harmonic filtering and reactive power compensation requirements in the future, saving both costs and space. Whether you need a small, wall-mounted unit for a specific application or a larger, expandable cubicle system for a complex installation, YT ELECTRIC has you covered.
AHFs are available in a range of voltages, with 200V to 690V being the most common. Some manufacturers even produce AHFs capable of operating at voltages up to V without the need for a step-up transformer, reducing both cost and physical footprint. YT ELECTRIC offers a diverse selection of AHFs across different voltage ranges. Our team of experts can assist you in determining the most suitable voltage option for your specific power system, ensuring seamless integration and optimal performance. Additionally, when connecting AHFs to medium voltage systems, step-up (or step-down) transformers can be used, although they may introduce additional impedance and potentially affect compensation performance. YT ELECTRIC's AHFs are designed to minimize these impacts, providing reliable operation even with transformer connections.
The Human-Machine Interface (HMI) of an AHF can vary significantly. Some offer a simple front panel, while others provide more advanced features such as graphical displays of current and voltage waveforms and multilingual support. YT ELECTRIC's AHFs come with an intuitive and user-friendly HMI. Our interface offers clear and detailed visualizations of power quality data, including real-time waveform displays and comprehensive harmonic analysis. It also supports multiple languages, making it accessible to a global user base. Moreover, our AHFs feature a web-based interface that enables in-depth monitoring and control functionality. Users can remotely access and manage the AHF's settings and performance data from anywhere with an internet connection, providing unprecedented convenience and flexibility.
Proper commissioning software can greatly simplify the installation and setup of an AHF. The software should include essential functions such as voltage and CT phase order self-check, CT polarity check, self-diagnosis, and self-calibration. YT ELECTRIC provides cutting-edge commissioning software that goes above and beyond these basic requirements. Our software not only automates the setup process but also offers detailed diagnostic reports and troubleshooting guides. This helps detect and correct installation errors early on, reducing the risk of future problems and significantly shortening the commissioning time. Without such software, the commissioning process can become complex and may require external assistance, increasing system costs.
Some advanced AHFs come equipped with built-in power quality analyzers that can calculate the required compensation in real-time. Additionally, web-based architectures enable the connection and monitoring of multiple AHFs on a site. YT ELECTRIC's AHFs are at the forefront of this technological advancement. Our products feature built-in, highly accurate power quality analyzers that continuously monitor and analyze the electrical environment. Through our proprietary web-based platform, operators can connect and manage multiple AHFs across a facility, gaining a comprehensive overview of the power quality status. This allows for the logging of events that could potentially disrupt production, as well as remote analysis and monitoring. With YT ELECTRIC's AHFs, you can stay ahead of power quality issues and ensure the efficient operation of your power system.
Often, AHFs are installed alongside existing or new detuned capacitor banks. Some suppliers offer the ability to control the steps of these capacitor banks directly from the AHF's control system. YT ELECTRIC's AHFs provide seamless integration with detuned capacitor banks. Our control system allows for precise control of the capacitor bank steps, leveraging the AHF's power quality monitoring and reporting capabilities. This integration enables the creation of hybrid var compensators (HVC), resulting in optimal system integration, efficient operation, and cost savings on the control system. By combining the strengths of AHFs and capacitor banks, YT ELECTRIC offers a comprehensive power quality solution.
In addition to canceling harmonics from traditional sources like AC and DC drives or UPS systems, AHFs should also be capable of mitigating triple harmonics that accumulate in the neutral wire. The increasing use of LED lighting and other single-phase loads in buildings can lead to high neutral wire currents, which pose a significant safety risk due to overheating. YT ELECTRIC's AHFs are designed to be easily configurable for both 3W and 4W applications. This ensures comprehensive harmonic cancellation, effectively reducing neutral wire currents and enhancing electrical safety. Our AHFs are the ideal choice for any installation where maintaining a safe and efficient electrical environment is a top priority.
By carefully considering each of these key selection criteria, you can select an Active Harmonic Filter that best meets the specific needs of your electrical power system. YT ELECTRIC's AHFs, with their outstanding features and performance across all these aspects, are the clear choice for those seeking reliable, efficient, and future-proof power quality solutions. Whether you are upgrading an existing system or designing a new one, trust YT ELECTRIC to deliver the highest quality AHFs and exceptional service to ensure the long-term reliability and efficiency of your electrical infrastructure.
Active Harmonic Filters are growing in popularity as a method to mitigate power quality issues. There are several factors to consider when specifying an active harmonic filter. Typical applications for active filters are compensation of variable frequency drives and data-centers to reduce the load on UPS systems or compensating the effects of renewable energy sources on the grid.
The general definition to describe this application is an analog or digital device that measures the power quality on the grid side. It then injects current to compensate any unwanted deviations from the standard 50 or 60 Hz supply. Deviations can be mitigated in full or partially.
There are suppliers that provide sensorless control eliminating the need for current transformers. This solution reduce the installation cost. Sensorless is not used in all applications so make sure to check the application with the supplier. Sensorless control or voltage control as it is sometimes defined compensates the total THD. It is not possible to select a single source such as a single VFD. On the plus-side it is possible to protect a sensitive subgrid from a noisy primary grid.
Depending on design, the filter has higher or lower losses. Check the losses as this will reduce the Life Cycle Cost on your investment. Some active filters have up to 1%-point lower losses, which depending on your user profile, means a potential for considerable financial savings if calculated LCC over 5 years.
Harmonics are normally seen in the odd. Common capacity for active filters is 25th or 50th harmonic. Sometimes there is a claim of being able to mitigate the 51st harmonic, which has little value as harmonic order of 51 and above are normally not important.
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Harmonics above the 50th are more difficult to measure as there are few PQ-meters that can handle such orders. There are however quite common sources such as Active Front End Drives that cause switching ripple above 3kHz, above the 60th harmonic (or above the 50th in 60 Hz systems).
There are a few Active Harmonic Filters capable of compensating such frequencies. Choose a filter according to the needs specified by your measurements.
A filter's capacity to compensate a certain harmonic order is only part of the story. Another important factor is de-rating, discussed below.
Some power quality phenomena occur extremely fast requiring the mitigation to be even faster. If your process is affected by fast flicker or transients, take special care to evaluate the response capacity of the filter. Flicker is a specific phenomena that normally requires special software to compensate flicker in a controlled environment.
Interharmonics is commonly caused by syncronisation issues. If your installation includes such interharmonic sources, the type of active filter changes and the vendor has to be consulted. This is a common issue on some types of older wind turbines.
In Europe there are strict guidelines regarding EMC. If you want to be sure that the active filter does not interfere, the filter must be fitted with a properly tuned EMC-filter.
An Active Harmonic Filter's rating is normally defined at nominal load, meaning at 50/60Hz. As the filter works further up the harmonics its capacity compared to nominal starts to de-rate. The de-rating curve is documented by all serious suppliers and should be available if you ask them.
A de-rating of 50%, at say the 13th harmonic, means that a 100A filter only has the capacity to compensate 50A at the 13th. Naturally if you have harmonics of higher order it becomes more important to check the de-rating.
De-rating is a matter of how robustly the filter is designed. Some suppliers offer zero de-rating up to the 7th before capacity starts to fall.
Most active filter suppliers offer several alternatives regarding installation. Wall mount, Cabinet and IP00 modules to install in cabinets. Efficient use of cabinet space translates to lower system cost. Some filters have a modular design and can be enhanced with further capacity without adding to the footprint.
As mentioned, a modular design of your Active Harmonic Filter enables you to adapt the filter to potential changes in your future power compensation needs. The modular design means that you can easily add to the filter's capacity within the existing cabinet, saving both cost and space.
Does the filter have built in commissioning software? Commissioning and service of Active Filters can be quite time consuming. Ask for a review of the support software included in the machine. Some suppliers have an extra charge for the necessary software. Minimum required functionality should be that the system performs a self-check of Voltage and CT phase order, CT polarity check, self-diagnosis, and self-calibration. Such features will quickly find installation errors before they can cause problems and will also shorten the needed commissioning time.
If the filter does not have this type of support software the commissioning becomes much more complex and might even require external support adding to the system cost.
There are different HMI setups. Some have a very simple front HMI while others include graphs showing the current and voltage waveforms and many further functions. A great added value is to have at least a web-based interface allowing in-depth monitoring and control functionality. Then no extra PQ-meter is necessary.
Active filters have a built in rudimentary power and power quality meter to calculate the required compensation. Some filter manufacturers make use of this fact and enable the user to connect all filters on site and company wide through a web based architecture. An operator can then have an overview of the status of all connected cabinets and log them. This enables the possibility to log events that could or should have caused production disturbances, status monitoring of individual filters as well as remote control capability. and text alerts to dedicated service personnel from the filter reduce response time dramatically.
Water-cooled Active Filters enable very good cooling of the IGBTs, the most critical component in the Active Filter. Water-cooling reduces overheating immensely, which increases availability in the same way as for Variable Frequency Drives. The power density of the installation is also improved.
Active Harmonic Filters are offered in a range of voltages. Most common ranges are 380'415V, up to 480 V. Higher voltages up to 600 and 690V are also available without step-up transformer, reducing foot print. Some suppliers have the capacity to supply MV ratings as well, normally using a step-up transformer. The active filter can then act as STATCOM.
In recent years several suppliers are offering battery connectivity to create a battery energy storage system for FCR and peak shaving. The active filters on-load capabilities are perfect for grid connectivity applications.
Recently a new type of sensorless solution make it much easier to install as no CTs are required which is standard for active harmonic filters. This method can not control specific frequencies but can be used to even mitigate noise from the grid.
Some filters offer resonance damping making them ideal in highly complex situations.
When building large systems with several filters acting together they are normally controlled by a master filter. In these cases some suppliers provide a multimaster option. In case the master-filter fail, another filter take up the master role and the system as a whole can continue filtering.