Application of APF+SVG in an international five-star hotel (2 × 1600kVA)

1.Project Overview

The Project is an international five-star hotel in China, with a total floor area of 30,000 square meters, 3 underground floors, 28 floors, 520 guest rooms, large banquet hall, Chinese and western restaurant, high-end SPA, thermostatic swimming pool, international conference center and underground parking lot. The power distribution system of the hotel adopts 11.4kV double-circuit power supply, under which two 1600kVA dry-type transformers (380V low-voltage side) are set. The original configuration is traditional capacitor reactance compensation cabinet (10 ways × 20kVAr), without APF.

With the intelligent upgrading of the hotel, a large number of nonlinear loads are input: frequency conversion system of central air conditioning (accounting for 45% of the total load), elevator frequency converter (12), LED intelligent lighting (100% coverage), high-power electromagnetic oven/steamer oven in the kitchen, UPS precision power supply, frequency conversion equipment for swimming pool heating, audio and video equipment in the conference center, etc., resulting in serious harmonic pollution, insufficient reactive power compensation, low power factor, excessive zero line current, overheating and aging of equipment, frequent crash of precision equipment and other problems in the low-voltage power distribution system. Capacitor bulging, contactor burnout, high oil temperature of transformer, network communication interruption, misoperation of elevator control system and other faults have occurred for many times, which seriously affect the hotel's high-end service quality and power safety. Meanwhile, the monthly power rate penalty is about. RMB 28000, high operation and maintenance cost.

2.Design of an improvement system

In order to completely solve the above power quality problems, combined with the long-term operation needs of the hotel, the original capacitor reactance compensation cabinet was completely removed in this reconstruction, and the SVG static reactive power generator was used for full replacement. The APF active power filter was added for centralized harmonic control, and the "SVG dynamic reactive power compensation+APF harmonic control+intelligent monitoring" three-in-one power quality control system was built to ensure the safe, stable, efficient and energy-saving operation of the hotel power distribution system.

3.Site condition of the hotel substation after improvement

Harmonic control: THDi reduces from 22.8% to ≤ 5%, all 5/7/11/13 harmonics meet the standard, zero line current reduces from 480A to ≤ 50A (≤ 10% phase line current), completely eliminating zero line overheating and electrical fire hazards.

Reactive compensation: the power factor is stable at 0.98-0.99, without over-compensation or under-compensation, the monthly free rate penalty was NT$150,000, and the annual saving penalty is NT$1,700,000.

Voltage stability: voltage fluctuation shall be controlled within ± 2%, three-phase current imbalance ≤ 2%, zero-to-ground potential difference of precision equipment ≤ 1V, so as to completely solve equipment crash, communication failure and misoperation problems.

Equipment loss: the operating temperature of the transformer is reduced from 85 – 95 ℃ to 60 – 70 ℃, the cable loss is reduced by 15% – 20%, the service life of the transformer, cable and precision equipment is extended by more than 2 times, and the annual operation and maintenance cost is saved by about NT$750,000.