AC mains filter

Description

1 / 6 AC mains filter [oooi] The present utility model refers to an electrical power filtering and compensation device applied to three-phase networks, consisting of a static and semi-automatic arrangement capable of performing, in a single device, the correction of both inductive and capacitive reactive power, as well as the attenuation of linear and non-linear harmonics, comprised in the fundamental frequency range from 50 Hz to 350 Hz, corresponding to the seventh harmonic.

[0002] In the state of the art, several devices are known for reactive power compensation and mitigation of harmonic distortions in three-phase electrical systems. Among the most widespread solutions are fixed or automatic capacitor banks, detuning reactors, tuned passive harmonic filters, and rotating synchronous compensators.These technologies, although widely used, have operational limitations when subjected to dynamic load variations, especially in environments with a high presence of non-linear loads. In general, conventional capacitor banks are designed to compensate for predominantly inductive loads, and are not able to act effectively in situations of excess capacitive reactive power, which can result in overvoltages and unsuitable operating conditions. In turn, passive filters have limited performance in specific frequency ranges, and undesirable resonance phenomena with the electrical network may occur, compromising system stability.

[0003] Additionally, rotary solutions traditionally used for reactive power compensation, although efficient under certain conditions, involve high installation and maintenance costs, as well as greater construction complexity and Petition 870260032283, dated 07 / 04 / 2026, page 8 / 20 2 / 6 lower energy efficiency when compared to static alternatives. Another relevant point refers to the lack of integration between the inductive and capacitive reactive compensation functions in a single device, which often requires the use of multiple devices, increasing the cost and complexity of the system.

[0004] Thus, it is clear that existing technologies do not fully meet current demands for more compact, fast-response systems with bidirectional reactive power control capabilities and efficient harmonic suppression across a wide frequency range. These limitations highlight the need for improved solutions that provide greater voltage stability, reduced electrical losses, and significant improvement in power quality in three-phase systems.

[0005] We can find in the state of the art documents that address specific heating equipment for sheds, such as, for example, US5805032 filed on 08 / 08 / 1998 and entitled “Electrical filter for attenuating oscillations in AC mains”, which aims to develop an electrical filter of the type mentioned in the introduction in order to avoid excitations of sub-harmonics or intermediate harmonics, that is, oscillations in the frequency range between the integral harmonics of the mains frequency, an exciting current source, for example, an arc furnace, with a frequency approximately equal to that of an unwanted intermediate harmonic, the resulting gain due to the filter is sufficiently small so that any feedback to a current regulator circuit, for such a current source, remains within tolerable limits. The distortion of the mains voltage at a distribution bus. Petition 870260032283, dated 07 / 04 / 2026, page 9 / 20 3 / 6 to which the filter is connected can be maintained within limit values ​​predetermined by the electric power utilities. The system now proposed presents an integrated and simplified approach, combining in a single static arrangement both capacitive and reactive power compensation, along with inductive and harmonic mitigation in a defined range. Unlike conventional solutions, which require multiple tuned filters and fine adjustments to avoid instabilities, the requested application uses the continuous interaction between a fixed capacitor bank (03) and a shunt reactor (04), promoting voltage stability and distortion reduction without the need for specific tuning for each harmonic order.

[0006] Another document that can be cited is EP3365963 and is named “System comprising a network, a filter and one or more drives”, and provides important features of the invention in the system are that it has a network, that is, in particular an electrical power supply network, a filter and one or more inverters, wherein the filter is connected, on the one hand, in particular on the input side, to the network and, on the other hand, in particular on the output side, to at least one power line for the inverters, wherein each inverter has an additional capacitance arrangement that is connected to the power line and disposed on the AC voltage connection of an inverter, whose DC voltage connection is connected to the DC voltage connection of an inverter on the motor side, whose AC voltage output feeds an electric motor, in particular in such a way that the two inverters disposed between the additional capacitance arrangement and the motor function as direct converters.The proposed application adopts a more comprehensive concept, not being conditioned on the presence of inverters or specific power electronics, acting directly on the three-phase network (06) with simultaneous compensation of inductive and capacitive reactive power. Petition 870260032283, dated 07 / 04 / 2026, page 10 / 20 4 / 6 In addition to harmonic suppression over a wider range. Unlike the compared solution, which requires capacitance distribution close to the loads and depends on the drive system configuration, the present system centralizes the actuation in a single static assembly, with semi-automatic operation and a focus on the overall stability of the network.

[0007] While traditional systems are heavily dependent on the behavior of specific loads and can present high design and operation complexity, the new system stands out for its constructive simplicity, semi-automatic operation and ability to adapt to different load conditions, simultaneously providing power factor improvement, THD reduction and greater overall energy efficiency.

[0008] The object of this model refers to a three-phase reactive power filtering and compensation system characterized by its ease of operation and reduced implementation and maintenance costs, designed to operate in an integrated manner to improve the quality of electrical energy. The device has a simplified construction configuration, allowing semi-automatic operation and high reliability under different load conditions.

[0009] Additionally, the system allows for different forms of electrical connection of its reactive elements, and can be configured in topologies equivalent to usual three-phase arrangements, in order to adapt to the characteristics of the network and the installation. Its functional structure integrates capacitive and inductive elements in the same physical assembly, promoting continuous interaction between these components for dynamic reactive power compensation.

[0010] Unlike conventional solutions, this system concentrates its functions in a single static piece of equipment, Petition 870260032283, dated 07 / 04 / 2026, page 11 / 20 5 / 6 eliminating the need for multiple distributed devices. This configuration provides greater operational efficiency, better energy utilization, and voltage stability, maintaining consistent performance even under load variations and the presence of harmonic distortions in the electrical network.

[0011] The object of this utility model is a three-phase semi-automatic filter, easy to operate and highly efficient, designed for reactive power correction and suppression of linear and non-linear harmonics. The system is built in a compact way, integrating in a single piece of equipment fixed capacitor banks (03) (C5 and C6) for compensation of inductive loads, and a three-phase shunt reactor (04) (T1) for absorption of excess capacitive loads, both from the capacitor bank itself (03) and from the electrical network, guaranteeing voltage balance and stability even during current peaks.

[0012] The following description and associated figures will make clear the object of this utility model patent.

[0013] Figure 01 represents a view of the assembled filter and its components.

[0014] The filter consists of a main circuit breaker (01) (QF1) and a contactor (02) (KM1), which is activated by a programmable timer (05), dividing the operating periods into capacitive and inductive modes, in accordance with ANEEL standards. For current flow control and protection, the system has three diodes (D1, D2, D3) associated with equalization resistors (R8, R9, R10), ensuring safe operation and absorption of instabilities.

[0015] The function of the shunt detuning reactor is coordinated with the capacitor banks, sizing its power in KVAR in order to maintain the current and voltage within stable limits, Petition 870260032283, dated 07 / 04 / 2026, page 12 / 20 6 / 6 even in the presence of non-linear loads. The new design allows the filter to perform, in a static and linear manner, functions traditionally performed by rotating synchronous compensators, simultaneously promoting the compensation of inductive and capacitive reactive power in a single system.

[0016] The system provides significant improvement in power quality in three-phase networks (06), achieving a reduction in total harmonic distortion (THD) below 3%, suppressing harmonics and balancing loads efficiently. Its integrated configuration reduces losses in transmission lines and industrial substations, ensuring active energy savings and continuous stability of the voltage supplied to connected equipment.

[0017] The semi-automatic filter, programmed in capacitive mode from 06:00h to 23:30h and in inductive mode from 00:00h to 06:00h, offers reliable and autonomous operation, meeting safety criteria, energy efficiency and current regulations, representing an innovation in reactive power management and harmonic filtering in three-phase electrical systems (06).

[0018] List of references (01) Circuit breaker; (02) Contactor; (03) Capacitor bank; (04) Shunt reactor; (05) Timer; (06) Three-phase network. Petition 870260032283, dated 07 / 04 / 2026, page 13 / 20

Claims

1 / 1 CLAIMS 1. AC NETWORK FILTER, applied to three-phase networks (06) characterized by comprising in a single piece of equipment, fixed capacitor banks (03) (C5 and C6) and a three-phase shunt reactor (04) (T1) physically integrated performs the correction of inductive and capacitive reactive power and the attenuation of harmonics between 50 Hz and 350 Hz and having a general circuit breaker (01) (QF1) and a contactor (02) (KM1) activated by a programmable timer (05) that divides the operating periods into capacitive and inductive mode three diodes (D1, D2, D3) associated with equalization resistors (R8, R9, R10) the shunt reactor (04) having its power in KVAR dimensioned in a coordinated manner with the capacitor banks (03). Petition 870260032283, dated 07 / 04 / 2026, page 14 / 20

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