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  • What energy-saving benefits can low-voltage

    Adopting a low-voltage reactive power compensation device. This is not only because low-voltage reactive power compensation can greatly improve the isolation factor of enterprises, but more importantly, it will also bring a series of energy-saving benefits to enterprises, mainly reflected in:

    1. Low voltage reactive power compensation can improve the power supply capacity of enterprise power equipment

    Based on the relevant knowledge of the enterprise power system, the power supply capacity of power supply and distribution equipment is mainly determined by the transmission capacity of the line and the capacity of the distribution transformer. For a certain capacity of electrical load, when its active power is constant, the lower the power factor, the greater the current that needs to be provided. After reactive power compensation, the reactive power required by the load is provided by the compensation capacitor, and the line and transformer only need to provide the active power. Therefore, the current on the line and transformer is greatly reduced, which can meet more load requirements and relatively improve the power supply capacity of the power supply and distribution equipment.

    2. Reactive power compensation can also reduce the fault problem of distribution transformers for enterprises and reduce losses on their power supply and distribution lines

    Due to the large electricity load within the enterprise, the current of the power supply and distribution lines and transformers is greatly reduced. The losses on the distribution transformers and power supply lines are proportional to the square of the current they pass through, so the losses can be greatly reduced and the possibility of power failure is also reduced. In addition, the use of low-voltage reactive power compensation can better improve the voltage quality of the enterprise's power supply terminal. After reactive power compensation, the current on the line can be significantly reduced, and the voltage loss on the line can be greatly reduced, improving the voltage of the originally low voltage power supply terminal, thus improving the voltage quality of the power supply terminal.

    3. Low voltage reactive power compensation device can save electricity costs and reduce electricity expenses for enterprises


  • Summary of experience and suggestions

    Active filters, as the most effective device for harmonic filtering and suppression in recent years, must be accurately installed during use. Therefore, based on years of practical operation of active filters, I remind everyone to pay attention to the following matters during use:

    Firstly, for the installation of active filters, users need to remember to choose shielded twisted pair when selecting the line source of the filter. This type of wiring can effectively eliminate some high-frequency interference signals or other signals, making the working efficiency of the active filter better.

    In addition, the wiring source should not be too long, as a long grounding wire means a significant increase in grounding inductance and resistance, which can seriously damage the common mode suppression ability of active power filters. A better method is to securely secure the shield of the active power filter to the casing at the equipment inlet using metal screws and star spring washers. The input and output lines of active power filters must be spaced apart and avoid parallelism to avoid reducing the effectiveness of active power filters.

    Moreover, the shell of the active power filter must have good contact with the chassis shell, and the installation of the ground wire must ensure accuracy.

    In addition, users should note that although active filters can integrate intelligent harmonic filtering, dynamic reactive power compensation, and three-phase load balancing functions, it is impossible for the filter set to absorb all harmonic currents and can only reduce the nth harmonic current flow into the system. The degree of reduction is closely related to the selection of filter parameters (i.e. capacitance Q, inductance L, and resistance R) and the system harmonic impedance. If the parameters are not selected properly, it is highly likely that the active filter will not achieve the expected filtering effect. Therefore, it is important to remind users to choose the optimal model of active power filter device based on the actual situation of the place of use when making actual choices.


  • What is the difference between reactive power

    Filter compensation is a method of reactive power compensation. Both of them compensate for reactive power, but conventional reactive power compensation can only compensate for reactive power and does not have the function of filtering out harmonics. They simply connect capacitor banks or capacitor banks in series with a certain reactance, which is mainly used to protect capacitors. The filter is also a capacitor bank and reactor connected in series, resonating at the characteristic harmonic frequency to achieve the purpose of absorbing harmonics. This is the main purpose of series reactors for filtering, and the presence of capacitors can also emit reactive power!

  • What are the sources of harmonics generated

    The harmonic sources of the power grid mainly come from three aspects:

    1. Low quality power generation generates harmonics: Due to the difficulty in achieving absolute symmetry in the production of three-phase windings and the difficulty in achieving absolute uniformity and consistency in the iron core of the generator, and other reasons, the power generation also generates some harmonics to some extent, but generally it is rare.

    2. It is the transmission and distribution system that generates harmonics: In the transmission and distribution system, harmonics are mainly generated by power transformers. Due to the saturation of the transformer core, the nonlinearity of the magnetization curve, and the consideration of economy when designing the transformer, its working magnetic density is selected in the near saturation section of the magnetization curve, which results in a sharp peak waveform of the magnetization current and therefore contains odd harmonics. Its size is related to the structural form of the magnetic circuit and the saturation degree of the iron core. The higher the saturation degree of the iron core, the farther the working point of the transformer deviates from the linearity, and the greater the harmonic current, with the third harmonic current reaching 0.5% of the rated current.

    3. It is the harmonic generated by electrical equipment: thyristor rectifier equipment. Due to the increasingly widespread application of thyristor rectification in many aspects such as electric locomotives, aluminum electrolysis cells, charging devices, switching power supplies, etc., it has caused a large amount of harmonics to the power grid. We know that the thyristor rectifier device adopts phase-shifting control, which absorbs the sine wave of the missing angle from the power grid, leaving another part of the missing angle sine wave in the power grid, obviously containing a large amount of harmonics in the remaining part. If the rectifier device is a single-phase rectifier circuit, it contains odd harmonic current when connected to an inductive load, with the content of the third harmonic reaching 30% of the fundamental wave; When connected to capacitive loads, there is an odd harmonic voltage, and its harmonic content increases with the increase of capacitance value. If the rectifier device is a three-phase fully controlled bridge 6-pulse rectifier, the transformer primary side and power supply line contain odd harmonic currents of 5 or more orders; If it is a 12 pulse rectifier, there are also 11 or more odd harmonic currents. Statistics show that the harmonics generated by the rectifier device account for nearly 40% of all harmonics, making it the largest harmonic source.


  • What are the characteristics of active filters?

    The existing power grid is generally a rigid system with low level of intelligence. The access and exit of power sources, as well as the transmission of electrical energy, lack good flexibility, and the coordination and control ability of the power grid is not ideal: the system's self-healing and self-healing capabilities completely rely on physical redundancy; The service form for users is simple, information is one-way, and there is a lack of a good information sharing mechanism.

    Compared with the existing power grid, the smart grid reflects the remarkable characteristics of high integration of power flow, information flow and business flow. Its progressiveness and advantages are mainly shown in:

    (1) Having a strong power grid infrastructure and technical support system, able to withstand various external disturbances and attacks, and able to adapt to large-scale access to clean and renewable energy, the strength of the power grid has been consolidated and improved.

    (2) The organic integration of information technology, sensor technology, automatic control technology and power grid infrastructure can obtain panoramic information of the power grid, and timely detect and predict potential faults. When a fault occurs, the power grid can quickly isolate the fault and achieve self recovery, thereby avoiding the occurrence of large-scale power outages.

    (3) The widespread application of technologies such as flexible AC/DC transmission, grid factory coordination, intelligent scheduling, power storage, and distribution automation has made the operation and control of the power grid more flexible and economical, and can adapt to the access of a large number of distributed power sources, microgrids, and electric vehicle charging and discharging facilities.

    (4) The comprehensive application of communication, information, and modern management technologies will greatly improve the efficiency of power equipment usage, reduce energy losses, and make the operation of the power grid more economical and efficient.

    (5) Realize high integration, sharing, and utilization of real-time and non real-time information, display comprehensive, complete, and detailed power grid operation status maps for operation management, and provide corresponding auxiliary decision-making support, control implementation plans, and response plans.

    (6) Establish a two-way interactive service mode, where users can real-time understand power supply capacity, power quality, electricity price status, and power outage information, and reasonably arrange the use of electrical appliances; Electric power enterprises can obtain detailed electricity consumption information from users and provide them with more value-added services.