Ortea Next solved the problem of bill penalties due to a monthly average power factor of less than 0.95 (minimum limit set by the regulatory body ARERA) at a major steel mill in north-west Italy.
Ortea Next analysis and planning
In the search for an effective solution, our Service department carried out accurate on-site measurements of the existing situation. After an analysis of the measured data and a precise and customised design phase, our engineers were able to propose a technical and economic solution that proved to be a winner compared to our competitors.
Technical Challenges: Transformation Cabins and Different Types of Loads
The plant is equipped with several MV/LV (Medium Voltage/Low Voltage) transformer substations, each of which feeds different types of loads. In some cases, the loads have slow work cycles exceeding one minute and, in this case, power factor correction switchboards equipped with traditional electromechanical contactors could be used. Other switchboards supply loads with fast duty cycles of less than one minute (e.g. hydraulic presses), shifting the choice of power factor correction equipment to solutions with static SCR inserters, i.e. capable of inserting reactive power very quickly (typically 150ms – 1s).
The optimal solution would have been to install one or the other solution on the bt side of each cabin, depending on the type of load being fed. Unfortunately, the only available space next to the MV delivery cabin was not sufficient to install all the necessary switchgear to achieve this.
Power Supply Alternatives Considered and Space Constraints
The customer also considered installing a MV power factor correction system, which presented two major problems:
Normally a MV power factor correction battery is always switched on. At times of low load, the power factor becomes capacitive, a situation that is not permitted precisely by the Regulator’s resolution, under penalty of disconnection from the distribution grid.
The installation of an automatic capacitor battery on the MV could have been envisaged, but it would not have been able to insert the capacitors in the timeframe required by fast loads (less than 1 minute). The very high cost of such a solution should also not be underestimated.
In addition, the use of a capacitor battery in MV, either fixed or automatic (normally realised with 2 or 3 steps at most), does not allow the same accuracy as a capacitor battery in bt, which normally has a high number of steps precisely to achieve this fine regulation.
Ortea Next’s Innovation: LV Power Factor Correction with Static SCR Inserters
The winning solution was to install a single LV power factor correction system, equipped with SCR static inserters, for the entire plant in the only available space, placing it on the MV side but feeding it in low voltage.
Technical and Economical Results: Ortea Next Efficiency
Thanks to the high performance of our reactive power regulator RPC8BGA, the voltage and current signals required to calculate the power factor were taken directly on the MV line. This resulted in a technically and economically efficient result, offering a tailor-made solution at a lower cost.
