PowerSave FAQ
Why does the PowerSave represent the next step in power factor correction?
The Edge PowerSave is an innovative, software-driven, power factor correction product that provides ultra-high correction at ultra-high efficiency.
The PowerSave innovation lies in proprietary Edge software algorithms running on a 200MHz DSP Microprocessor and Edge’s patented Capacitor Digital Array. These remove the need for an inefficient reactor while still ensuring components are fully protected and use a combination of “coarse” and “fine” KVAr steps achieve a high-power factor at peak, typically 0.99. Algorithms restrict leading kVAr from occurring, a disadvantage of legacy ‘linear’ capacitor arrays, while still achieving a near unity power factor. Fine tuning continues to allow for full kVAr compensation regardless if PFC capacitor degradation occurs over the long term by intelligently sensing kVAr availability. This sophisticated correction eliminates the need for capacitor replacement over the life of the product.
The PowerSave is supported by an online customer portal that validates performance and provides real-time remote service and monitoring. This provides detailed visibility of energy consumption plus immediate awareness and reaction to any changes in PowerSave performance.
How efficient is the PowerSave in comparison to other PFC technologies?
The use of capacitors remains the most efficient approach to PFC correction as Capacitors dissipate very little power and thus have very low heat generation. In addition, Edge’s patented semiconductor switching, and software algorithms enable a reactor-less, low power loss approach to PFC. This allows the PowerSave to operate at a record efficiency of only 2 Watt-loss per kVAr.
This represents a significant innovation in PFC in comparison with traditional PFC products that still rely on hot, heavy and lossy reactors which are at best able to achieve 5.5 Watt-loss per kVAr. This translates into a nearly three-fold improvement in operating costs for the end-consumer.
Other Active Power Filters (APF’s) technologies used for PFC such as STATCOMS/SVGs are extremely inefficient by comparison. Due to the complex and continuous (few uS) high frequency Power Semiconductor switching, these technologies have high aggregated switching losses. Combined with complex double power conversion topologies, these products negatively impact the customer with significant real power costs ($/kWh charges). This high heat generation results in accelerated equipment failure, especially temperature degradation of the many electrolytic capacitors used in these APF’s that typically precipitates shortened warranty periods.
SVGs operate at an efficiency of typically 97%, or 30W per kVAr. This is >12x less efficient than PowerSave technology and severely reduces PFC net benefit.
In comparison, the Edge PowerSave uses high reliability, self-healing, low loss film capacitors to ensure maximum efficiency and product life.
What is the PowerSave power density?
The PowerSave is able to operate very effectively at smaller floor areas, as the PowerSave’s very low heat generation and high efficiency allow for significantly higher power density (kVAr/m2) than legacy PFC products. This advantage is multiplied in comparison to SVG technologies that require very high, clean airflow and generate high power losses. The PowerSave very low internal temperature rise also protects the PFC Capacitors’ degradation and Electronics.
What is the PowerSave response speed?
The PowerSave does not use the legacy slow unreliable electromechanical contactors. Instead, the advanced high-speed semiconductor switching under software control running on a 200MHz DSP microprocessor allows for correction at <250 ms if needed. This high-speed software control also guarantees the PFC Capacitors are switched at the benign and optimum points under all Line and Load conditions to fully protect the Capacitors from Voltage or Surge Currents.
Since customer meter billing PF is typically in 15- or 30-minute intervals, high response speeds have significant diminishing returns in terms of impact on customer billing. Higher response speeds typically only serve to unnecessary increase it results in high heat generation that is unnecessary. The Edge PFC typically corrects every minute for minimum heat generation and maximum Customer KW/Hr Savings, but
For any unusual applications, if needed, the PowerSave can be set to correct <250 ms.
How does the PowerSave manage harmonic environments?
Edge’s software algorithms and 200 MHz microprocessor fully protect PowerSave capacitors by directly monitoring actual PFC capacitor current through internal Current Transformers (CT’s). High frequency monitoring ensures PowerSave capacitors are fully protected from any excess rated ripple currents including any Currents from Voltage Harmonics (vTHD). Additionally, this suppresses any risk of resonance.
Full protection through high-frequency monitoring allows for PFC without the need for inefficient large, heavy, and lossy legacy Reactors.
Noting that the maximum allowable distributor vTHD is <5%, the PowerSave operates normally up to 12% vTHD. This means the PowerSave performs perfectly within and well beyond Distributor vTHD requirements. Additionally, very high current harmonics (iTHD) have no impact on the PowerSave operation.
Is the PowerSave able to operate with unbalanced phases?
Upon commissioning, Edge Electrons is able to immediately advise of any Current or kVAr imbalances measured thanks to 24/7 remote monitoring through the PowerSave Customer Service platform.
PowerSave Software Algorithms can then be remotely and dynamically optimized for improved PF and maximum Customer savings.
Life, Reliability and Performance
Edge’s innovative approach to reactor-less PFC with intelligent full capacitor protection
This features address area’s critical to PFC life, reliability and performance:
- Low heat
Electronic components are vulnerable to heat. Edge’s reactor-less approach to PFC has created the lowest heat approach available ensuring the risk of heat degradation to PFC components, installation and safety is minimised. - Semiconductor switching, not contactors
A weakness of traditional PFC, the PowerSave’s use of advanced high-speed semiconductor switching which does not suffer from rapid degradation under high switching and therefore does not jeopardise the capacitor lifespan. - Full protection of high-reliability capacitors
By ensuring that capacitors are never exposed to harmful excess rated ripple currents the PowerSave greatly - Full utilisation of capacitors
PowerSave performance is maintained throughout product life thanks to Edge’s patented software and digital array intelligently sensing kVAr availability. Furthermore, Edge’s remote service is capable of fine-tuning algorithms to specific site conditions and load profiles as these change over time - 24/7 remote monitoring and service
The PowerSave customer portal ensures that PowerSave performance is constantly being monitored. This brings the key advantage of not requiring expensive, recurring scheduled maintenance costs. Issues are immediately identified as soon as they occur and can be fully or partially resolved through remote service.
How is the parallel resonance and associated harmonic amplification prevented?
As long term experienced Power Electronics and Software people, we approached, from first fundamental principles, the critical factor in protecting the PFC Capacitors from exceeding Rated Currents through the Caps, by directly and accurately Measuring the actual total Current passing through the Caps with internal Current Transformers (CT’s).
The CT’s on the Caps simply directly Monitor the TOTAL Cap Currents including – Fundamental, Harmonics, and any Resonance Currents, and communicates Cap Current data to the DSP.
Also, the DSP Monitors the relevant Line Voltages, and also knows what Caps are engaged, and therefore can Calculate the Fundamental Cap Currents, and in subtracting from the Total directly Measured Currents, leaves the Harmonic and any Resonant Currents.
Again, to make sure the Caps are operating within their Total Specified Rated Currents (which we Derate), and that includes Harmonic and Resonant Currents, and the DSP action accordingly is related to the Derated Total Currents Levels allowed and set in the DSP.
The key here, is simply, we know directly and accurately the Total Current through the Caps, the complicated and also approximate guestimate when specifying Reactors depending upon the Installed environment, but in contrast, we can install our Standard Powersave Units, without any consideration on the environment, because we directly Monitor the Total Cap Currents.
Since we know exactly the Total Caps Currents, and in addition we DERATE these Caps Current Levels from the Cap Specified Maximum Ripple Current, anywhere from 25% to 50%. When these set Derated Levels of Total Cap Currents are exceeded, the Controller Software removes the Caps. Then we have a Programmable routine, where this cycle is repeated once every 5 minutes, where the Caps are engaged, and the Cap Currents measured again. If normal on any of these cycles, the Powersave Unit just continues normal operation, but if the Caps Currents set Derated Values are exceeded for a full 6 cycles (30 minutes) then the Caps are kept out and a critical Alarm is generated.
In addition, to make sure the critical Cap Currents cannot be exceeded, the Controller Monitors the Grid vTHD, as you know, it is the Voltage Harmonics that drive the Cap Currents.
So again, as a second check, when the vTHD reaches a set Level of 12%, we remove the Caps, then every 5 minutes for 6 tries, the Controller checks the vTHD, as could be momentary. If the vTHD is still 12% after 6 cycles (30 minutes), the Caps a removed and a Critical Alarm is sent.
Since the Legislated vTHD is 5%, very few places 7.2%, so at 12% there are very serious extreme Line problems that the Customer has to fix.
We normally see 2-3% with the present Installations.
Please note, we do Monitor each PowerSave Unit here in Manila, so we have full Diagnostics and Remote Control, to make sure maximum PFC Cost Savings are achieved for Customers.
How exactly is the micro-stepping achieved?
This is an Edge Patent, that the Capacitors are arranged in a Digital Array under control of the DSP Software Algorithms.
So again, as Electronics people, we were looking at the plot of – PF on the Y-Axis, and KVAR on the X-Axis, as the KVAR is reduced to drive the PF to Target 1 up the Y-Axis, the PF approach to “1” is quite asymptotic, hence the concept of a Capacitor Digital Array to make sure –
a)”Coarse” KVAR Steps for the larger Caps in the Array, and “Fine” KVAR Steps for the smaller Caps that are toggled with the Controller Algorithms, as the PF is driven asymptotically up the Y-Axis close to, or at, Target 1.
b)The Power Distributors have also may it clear in the last few years, that they will not allow – Leading KVAR to be placed on the Grid from Overcompensated PFC Units. With legacy typical Linear Cap Array that Targets 1, they can add – Leading KVAR to optimize PF, or lower PF to stop adding Leading KVAR on the Grid.
With the Edge Cap Digital Array, the Controller Algorithm allows the asymptotic PF curve close to, or at, Target 1, without Leading KVAR to be added to the Grid.