With the development of technology, the automation degree of business hotel is higher and higher, also there are more and more automatic control equipment, EIB intelligent lighting system has gradually become the standard configuration of upscale business hotel. To save energy, frequency converter had been used a lot in air-conditioning and elevator systems. But the above equipment will produce serious harmonic during working. Take converter as an example, it has both rectifier and high frequency inverter, and it will produce a large number of harmonics on both high and low frequency band. The harmonic has been listed as the big three hazard in electrical system together with electromagnetic interference and low power factor. So the measurement and analysis to harmonic are one of important task of electric system analysis and control, are the important precondition to carry out the relay protection、faulty measurement and other works.
The non-linear loads in business hotel produce higher harmonic objectively , due to harmonic content is too large, it will not only pollute power supply grid, but also has negative influence to communication and electric equipment of business hotel. The pollution of power grid will cause that the components in power grid will produce additional losses, reduce the use efficiency of power generation、distribution and consumption equipment, even make circuit overheat to cause fire hazard; due to the effect of current harmonic, power grid voltage will also be effected, to make that the THD of voltage over the national standard.
The hazard of harmonic to business hotel:
(1)equipment will produce additional loss, effect the normal working of electrical equipment of business hotel, produce mechanical vibration、noise、over voltage，make the transformer、capacitor、cable and others over heated, insulation aging and short service life;
(2)interference the nearby communication system, cause noise and reduce communication quality in less severe case, but can cause the loss of message and make communication system unable to work in seriously cases.
(3)due to logistics requirement of business hotel, loads start and stop frequently which cause grid surge and serious transient. The voltage and current mutation will cause over voltage, greatly shorten the service life of electric equipment, virtually increase equipment investment cost.
(4)current harmonic index exceed the standard badly, cause a certain impact on EIB and other systems, often cause system fault.
To guarantee the high reliability requirement of business hotel running, during the design and construction stage, at present mainly take the following measures to prevent the interference from harmonics.
(1) design dedicated circuit of power supply for electronic equipment, try to avoid that harmonic inject through power supply circuit.
(2) install line filter for equipment that easy to be disturbed, cancel or suppress harmonic component, achieve the purpose to purify power supply.
(3) make the layout wiring of these equipment away from the circuit with serious harmonic current distortion as far as possible, to avoid space electromagnetic interference.
However, these measures are all not solving the harmonic pollution at the source.
Starting the purpose to improve system electric quality、guarantee the equipment safe and normal running、 integrate improve the equipment working efficiency and electric energy using efficiency, you can use HTQF low voltage active power harmonic filter, in the meantime of cancelling the harmonic, it can absorb the harmonic in circuit effectively and cleanly, achieve the effect of optimize line electric quality, reduce harmonic hazard, protect equipment running, save electricity bill and so on.