Background introduction

In recent years, with the accelerating pace of urban modernization, intelligent buildings have gradually developed rapidly to intelligent buildings, intelligent blocks, and intelligent cities. In China, because the concept of intelligent building conforms to the concept of ecological and harmonious development of sustainable development, the intelligent building in China mainly highlights the characteristics of intelligent buildings, such as energy saving, environmental protection, practicability, advanced nature and sustainable development. Compared with intelligent buildings in other countries, China pays more attention to energy saving and emission reduction of intelligent buildings. What we pursue more is the high efficiency and low carbon of intelligent buildings. All this has a very positive role in promoting energy conservation and emission reduction and reducing energy consumption.

Existing problems

Computers, printers, photocopiers, elevators, energy-saving lamps, UPS, energy-saving air conditioners, LED displays, etc. are widely used in intelligent buildings. Most of these devices have small capacity, but a large number of them have a great impact on power quality as a whole. Non-linear loads are mainly used in intelligent buildings, and their load characteristics mainly include the following aspects:

① There are many single-phase electrical equipment, and its power consumption generally accounts for about 50% of the total. The use of single-phase power supply causes unbalanced three-phase distribution load, excessive neutral line current and neutral point offset;

② Because the electric equipment is non-linear, its harmonic content is high and its power factor is low. 3K times current harmonics will also be superimposed on the neutral line, resulting in the decline of power quality of intelligent buildings. The research shows that intelligent buildings are an important source of harmonics;

③ Most electric equipment have high requirements for power quality and are sensitive to harmonics.

Product introduction of reactive power compensation design

According to different intelligent building load types and transformer capacity, the reactive power compensation design capacity configuration between the incoming cabinet and the load. Among them, SFR-M series intelligent dynamic harmonic suppression low-voltage power capacitor module is specially aimed at the harmonic and power factor problems in the 0.4kV low-voltage distribution network where the harmonic pollution is serious, so as to improve the power factor, effectively suppress harmonics, reduce line loss Integrated reactive power compensation products to improve power quality.

The intelligent dynamic harmonic suppression reactive power compensation module includes: digital processing circuit, highly integrated detection, control, protection, display unit, zero crossing switching module, discharge and air cooling unit, filter reactor, low-voltage filter power capacitor and functional module operation state indication circuit. This series of modules is a new generation of dynamic filter compensation equipment for 0.4kV low-voltage distribution network. It is suitable for electric field switching with frequent load changes and high requirements for voltage qualification rate. The total time of judging switching and switching actions is ≤ 20ms, which is a typical dynamic tracking compensation integrated module.

Technical parameter

Product specifications

Typical design

The example uses the company's intelligent dynamic harmonic suppression reactive power compensation module, configures the WGK-31-203 controller, determines the compensation capacity and reactance coefficient according to the demand, improves the system power factor, and suppresses the harmonic component. When the compensation capacity needs to be increased, just increase the number of dynamic compensation modules and change the specifications of knife-fuse switch and fuse.

Matching controller

Technical parameter

Hotel in Pattaya Thailand is a resort hotel contains 555 guest rooms. A great amount of electric devices brings large number of power consumption and it request a higher power quality environment. The power substation system of the hotel is combines by 4pcs 2000kVA transformer, the nature power factor is about 0.8. The supporting ratio of the 4pcs transformers is almost the same furthermore the nonlinear equipment capacity is comparatively small. In this regard, the resort hotel equipped the Sfere Electric SFR-L 600kvar intelligent capacitor power bank.The intelligent capacitor bank has fast response for the reactive power compensation which insure the average power factor of the hotel is ≥0.95. It reduce the reactive power flowing in the power system and reduce the electricity billing cost, enhance the voltage stability.

Advantages:

1.Reactive power compensation module use the zero-cross-switching technology, fast response and less inrush.

2.The reactive power compensation controller issues switching commands through the network port. The controller and several compensation modules are connected hand in hand with network cables. The wiring workload of the control part is greatly reduced, and the number of fault points is significantly reduced.

3.The stainless steel shell of the reactive power compensation module is more suitable for the environment with high humidity and is safe and stable. Thailand has high temperatures all year round, and tropical cyclones from the ocean often strike, and the average humidity generally falls between 75 and 100%.

4.The reactive power compensation module has a compact structure and saves space in the power distribution room of the user. Easy to install and easy to maintain.

5.The reactive power compensation module is highly reliable and supports switching times ≥ 1.2 million times.

A Jiangsu industrial park covers an area of 350 mu, has a number of semiconductor and related accessories based electronic enterprises. There are three power transformation and distribution rooms in the park, total six 1600 kVA transformers with the capacity of 9600 kVA. The load of the park is as follows: about 55% for motor load, 35% for electric heating load and 10% for other loads. Among them, frequency converter, frequency conversion air conditioner, LED lighting and so on are the main non-linear equipment. According to the load characteristics, 600 kvar harmonic suppression reactive power compensation equipment is installed beside the low-voltage incoming cabinet of 6 transformers, and the core component is SFR-M series harmonic suppression reactive power compensation module (reactance coefficient 7%).

The natural power factor was about 0.82 when the reactive power compensation device is not put into operation.The voltage at the low voltage side was about 370V, THDi was about 18% ( 5th and 7th harmonics are obvious). At the same time, some equipment can not work normally when the large capacity motor is started. After the reactive power compensation device was put into operation, the monthly average power factor of the park was increased to 0.97, and the voltage at the low voltage side was increased to 380,THDi was reduced to 8%, there is no situation that some equipment can not work normally when the large capacity motor started, and the power environment of the user is obviously improved.