Power quality characteristics of modern commercial buildings:
Nowadays, with the development of cities, high-rise commercial buildings continue to increase, which is what we usually call buildings. In the power distribution system of these high-rise commercial buildings, due to the large number of nonlinear load power equipment and electricity that generate harmonics Widespread application of facilities, such as: lighting systems with electronic rectification; modern office systems such as personal computers; data exchange systems (IDC computer rooms as data processing and exchange storage platforms); building water supply, heating, fresh air, air conditioning, Elevators, fire fighting systems; and building monitoring systems for building security, etc. A large number of harmonic currents are injected into the distribution network, and the grid voltage also produces different degrees of distortion. This kind of harmonic "pollution" will cause serious harm to the distribution network and users, and constitute the operation of the building's power supply and distribution system. At the same time, a large number of reactive harmonic currents are injected into the system, occupying the system capacity, increasing the burden of system operation, causing unnecessary waste of electric energy while causing harm to the system, and seriously reducing the power quality of the power system.
Characteristics and status quo of harmonic pollution in modern commercial buildings:
Due to the use of a large number of single-phase non-linear loads in the building power distribution system, the harmonic components are all dominated by the third order, which causes the system neutral current to be too large. The third harmonic and its multiples will form a circulating current in the windings of the delta-connected transformer, causing the winding to overheat; for the full-star-connected transformer, when the neutral point of the winding is pressed to the ground, the distributed capacitance in the grid on this side is relatively high. When large or equipped with a parallel capacitor with a neutral point grounded, the third harmonic resonance may be formed, which will increase the additional loss of the transformer; at the same time, excessive neutral current is prominent in the system where the neutral line is less than the carrying capacity of the phase line. , The loss increases. When the load capacity of the zero line of the system is exceeded, the zero line protection circuit breaker is not set, which will cause greater harm and loss to the system.
The harm of harmonics to the power distribution system of modern commercial buildings:
1. Seriously endanger the safety of system operation;
1.1 Overheating of transmission lines may cause electrical fires;
1.2 Power capacitors are easily broken down and cause electrical accidents;
1.3 Decreasing the breaking capacity of the circuit breaker may easily cause the protection device to malfunction, cause unexplained power outages, and increase complaints due to dissatisfaction of the owner;
1.4 Various electrical accidents are likely to cause casualties and greater losses;
2. Interfere with the normal operation of the weak current system;
2.1 Interfering with the building monitoring system and causing its disorder;
2.2 Data loss caused by interference with the communication system causes complaints from the user;
2.3 Inaccurate indications and measurements of measuring and measuring instruments, causing electricity disputes between the property management department and the landlord and tenant;
3. The loss caused by harmonics is large, which wastes a lot of electric energy and causes losses;
3.1 Reduce the power factor of the current and increase the proportion of useless work;
3.2 The loss of harmonic reactive power itself wastes a lot of electric energy;
3.3 Frequent electrical system failures, serious aging of various electrical equipment, accelerated renewal, and consumption of a lot of manpower and material resources.
Our company provides corresponding power quality management product solutions for commercial buildings. It is equipped with a combination of dynamic compensation capacitors and reactors. The reactor is equipped with 14% reactance, which greatly suppresses the influence of the third harmonic on the capacitor. At the same time, the configuration of SVG/APF can control harmonics. It can also solve the problem of unbalanced three-phase commercial load.
The necessity and benefits of harmonic control:
After the harmonic protection device controls the system harmonic pollution, it can greatly reduce the harmonic content in the system, reduce the system failure rate, eliminate system safety hazards, improve the utilization rate of the system capacity, reduce the amount of daily maintenance, and save energy
1. Maintain the reliability and continuity of the power distribution system;
2. Reduce the heating, aging, derating and damage of the equipment caused by harmonics, improve the use efficiency of the equipment, release the system capacity, and reduce the investment in electrical equipment;
3. Eliminate a hidden danger point of the system and upgrade the safety protection;
4. Improve the power factor of electric energy;
5. Improve power quality, save energy and reduce emissions, and protect the environment;
6. Reduce complaints caused by power quality problems and improve service quality.