Harmonic analysis and multi-stage filter design for a large bleach production facility

Modern sodium chlorate or sodium hypochlorite-making processes (commonly known as “bleach”) takes salt and water through an electrolytic process. The electrolytic process requires a significant amount of DC power. Bleach production plants, equipped with rectifiers, can generate potentially damaging harmonic currents if not mitigated or controlled. This paper presents a combination of harmonic mitigation methods applied at a large bleach production facility. The harmonic mitigation methods consisted of transformer phase shifting and multi-stage harmonic filter banks applied at 34.5 kV to satisfy IEEE Std 519-1992 harmonic distortion limits at the point of common coupling. The authors faced several challenges with the harmonic filter design that included various operating conditions within the facility as well as numerous utility substation loading and capacitor combinations.