Indiana Wastewater Treatment Plant

Problem

Wastewater treatment plant retrofit project needed additional harmonic mitigation in the form of passive harmonic filters. The plant operator required contactor control and feedback that the harmonic filters were in operation. A combination of 16 different non-linear loads ranging from 10 to 40 HP required harmonic mitigation.

Solution

HGP passive harmonic filters with PQconnect technology were applied to this wastewater treatment plant. This solution enabled the operator to control the filters remotely, and adjust the contactor drop out and pick up as needed. The operator knew that the filters were in continuous operation remotely.

Virginia Pump Stations

Problem

Renovation of two pump stations in Virginia that required harmonic mitigation to meet IEEE-519 requirements. One pump station had four 125 HP variable frequency drives and pumps, and a second pump station had four 350 HP drives and pumps. Both pump stations easily exceeded IEEE requirements for allowable harmonic distortion.

Solution

The owner preferred a drive-applied harmonic solution for each station. TCI HGP passive harmonic filters were applied to each drive, reducing total harmonic distortion to less than 5% TDD. The HGP can maintain 5% all the way down to 50% load, if necessary.

Iowa Wastewater Treatment Plant

Problem

The electrical engineering firm was in the process of renovating a WWTP in Iowa which required several small to medium horsepower VFDs. They wanted a design that met IEEE-519 and was simple for their customer. With VFDs on several pieces of OEM equipment, from small pumps to larger aeration systems with blowers, it was going to be difficult to specify larger, more complicated, and expensive 18 pulse or active front end VFDs that were uniform on all of the different pieces of equipment. OEM suppliers often do not offer the option of specifying the type or brand of VFD that comes with their equipment.

Solution

Adding just one TCI HGA active harmonic filter, with a few inexpensive line reactors placed at certain loads, gave the plant a single, cost-effective harmonic solution that worked effectively with the variety of OEM equipment. The active filter was placed at the service entrance, filtering the entire plant, and resulting in a large cost and space saving package. The active filter was also sized for power factor correction due to local utility demands. While operating in “dual mode,” the filter lowered harmonics down to 5% ITHD and kept power factor at a .95 lagging.

Illinois Wastewater Treatment Plant Renovation

Problem

New state requirements for phosphorus removal meant that the wastewater treatment facility in St. Charles, Illinois had to be upgraded to accommodate the change. This meant that the facility needed to convert to a three-stage A2O system, with aerobic, anoxic, and anaerobic zones for biological phosphorus removal. They needed to add a new internal recycle pump station, a primary sludge fermenter, and replace sludge and biogas storage tanks. In the process, they rehabilitated the digesters and biogas system as well. Some of the changes required adding non-linear load variable frequency drives which added harmonics to the system.

Solution

The addition of HGP Passive Harmonic Filters on non-linear VFD loads will reduce harmonic distortion to less than 5%. Renovations like this typically include additional stages of pumping that require VFDs, and thus additional harmonics for the entire plant. Applying passive filters to the new VFDs is an easy and inexpensive way to get the facility back to a low level of harmonic content, which is ideal for the equipment in the entire plant. The article in Treatment Plant Operator magazine, Upgrading to a Bio-P Process Required Open Communication and a Proactive, Patient Approach at Wastewater Facility, by Jim Force, describes in detail how the wastewater facility had to be upgraded, and is the source of the information and picture for this case study.

Alabama Reverse Osmosis Stations

Problem

The renovation of two reverse osmosis stations at a wastewater treatment plant in Alabama required harmonic mitigation. Each station’s total non-linear load, and resulting harmonic distortion, required 670 corrective amps. Without a solution the distortion would potentially cause the equipment to go off-line due to nuisance tripping. The owner considered the addition of multiple 300 amp active filters in parallel, equating to three units per station. Due to space and cost constraints, the customer struggles with this solution.

Solution

TCI offers the largest single-unit amp rated active filters in the market, an ideal solution for this application. The owner installed one 700 amp TCI active harmonic filter per station. The benefits included significant cost savings over alternative solutions and the smaller footprint allowed the installation to proceed without other costly modifications. The stations now meet the IEEE-519 requirements eliminating the nuisance tripping caused by harmonics.

Southeastern Aquarium

Problem

The pumping requirement was immense at one of the largest aquariums in the world, in the southeastern region of the United States. The large number of pumps and horsepower required to move so much water resulted in enough VFD load to require significant harmonic mitigation. An initial set of active harmonic filters from another manufacturer was installed for the application. Immediately there were problems between the active filters and the VFDs. The drives were tripping due to an inrush of current from the active filters coming online. The pumps were not able to move water with the drives offline due to the harmonic filters.

Solution

The facility was retrofitted with TCI HGA active harmonic filters. The HGA is designed with a pre-charge circuit that allows for the filter to slowly come online, which allows the VFDs to operate continuously. The pre-charge circuit enables the harmonic filters to softly engage with the system. The operation is not affected by any inrush surges from the HGA active filters but receives the benefit of the harmonic mitigation.