Reactive power compensation circuit and capacitor compensation module

Abstract

The application discloses a reactive power compensation circuit and a capacitor compensation module. The reactive power compensation circuit comprises a magnetic balance coil including a primary winding and a secondary winding; a first loop including a first capacitor, and the first capacitor is connected in series with the primary winding; a second loop including an impedance adjustment unit connected in series with the secondary winding, the impedance adjustment unit being used for making the impedance characteristic of the second loop capacitive when a fundamental wave voltage is applied, and / or making the impedance characteristic of the second loop inductive when in a harmonic environment; and the second loop being connected with the first loop, used for being capacitive when the first loop is applied with the fundamental wave voltage, so that the impedance of the magnetic balance coil in the first loop is reduced, to guarantee that the first capacitor compensates for the reactive power, and / or being inductive when the first loop is in the harmonic environment, so that the impedance of the magnetic balance coil in the first loop is increased, to suppress the harmonic current in the first capacitor. Therefore, the application can realize better reactive compensation by using a power capacitor (i.e. the first capacitor).

Description

Technical Field

[0001] This application relates to the field of power system technology, specifically to a reactive power compensation circuit and a capacitor compensation module. Background Technology

[0002] The presence of numerous inductive loads in a power system can lead to a decrease in the power factor. An excessively low power factor can cause a series of adverse effects, such as: 1) Decreased energy conversion efficiency, leading to increased energy consumption and reduced system efficiency; 2) Increased current in the grid, resulting in greater losses on transmission lines and increased line losses in the power supply system; 3) Increased internal losses in connected electrical equipment due to a low power factor, leading to higher operating temperatures and impacting equipment reliability and lifespan; 4) Penalties imposed on companies connected to the grid due to a low power factor, increasing electricity costs. Furthermore, a decreased power factor also wastes electrical resources; therefore, measures must be taken to minimize the impact of a low power factor.

[0003] Using power capacitors for reactive power compensation (or reactive power compensation) in power systems is one of the common measures to improve the power factor of power systems. Power capacitors can effectively compensate for reactive power and improve the power factor.

[0004] However, in practical applications, when using power capacitors for reactive power compensation, the impedance of power capacitors decreases with increasing frequency. Therefore, harmonics in the power system can amplify the harmonic current flowing into the power capacitors, leading to damage. Thus, power capacitors are easily affected by harmonics in the power system. In conceiving and implementing this application, the inventors discovered that how to better utilize power capacitors for reactive power compensation is a technical problem that urgently needs to be solved by those skilled in the art.

[0005] The preceding description is intended to provide general background information and does not necessarily constitute prior art. Utility Model Content

[0006] To address the aforementioned technical problems, this application provides a reactive power compensation circuit and a capacitor compensation module, which can achieve better reactive power compensation using power capacitors.

[0007] This application provides a reactive power compensation circuit, including: a first circuit, a second circuit, and a magnetic balance coil; the magnetic balance coil includes a primary winding and a secondary winding; the first circuit includes a first capacitor connected in series with the primary winding; the second circuit includes an impedance adjustment unit connected in series with the secondary winding, the impedance adjustment unit being used to make the impedance characteristic of the second circuit capacitive when a fundamental voltage is applied, and / or to make the impedance characteristic of the second circuit in a harmonic environment in an inductive environment; the second circuit is connected to the first circuit, and is used to be capacitive when a fundamental voltage is applied to the first circuit, so that the impedance of the magnetic balance coil in the first circuit decreases, thereby ensuring that the first capacitor compensates for reactive power, and / or to be inductive when the first circuit is in a harmonic environment, so that the impedance of the magnetic balance coil in the first circuit increases, thereby suppressing harmonic current in the first capacitor.

[0008] Optionally, the impedance adjustment unit includes an inductor and a second capacitor; the secondary winding, the inductor, and the second capacitor are connected in series.

[0009] Optionally, the terminals of the primary and secondary windings in the magnetic balance coil are reversed.

[0010] Optionally, the inductor is a magnetic ring coil.

[0011] Optionally, the primary winding is a magnetic ring coil; and / or, the secondary winding is a magnetic ring coil.

[0012] Optionally, the range of inductance values ​​is: ,in, This represents the inductive reactance of the inductor. This represents the capacitive reactance of the second capacitor; where, under harmonic conditions, the impedances of the first and second circuits are in opposite directions and the first circuit is capacitive, the inductance value is... This makes the second circuit inductive, and makes the magnetic flux generated by the first harmonic current in the primary winding of the first circuit and the magnetic flux generated by the second harmonic current in the secondary winding of the second circuit in the same direction and mutually reinforce each other, so as to increase the impedance of the magnetic balance coil to the first circuit; wherein, the first harmonic current is a capacitive current and the second harmonic current is an inductive current.

[0013] Optionally, the harmonic order of the harmonic environment is k, and k≥3.

[0014] Optionally, the turns ratio of the primary winding to the secondary winding is set to be equal to the ratio of the first fundamental current in the first circuit to the second fundamental current in the second circuit when the fundamental voltage is applied to the first circuit. This is so that when the first fundamental current and the second fundamental current flow into the magnetic balance coil in opposite directions at their corresponding terminals, the magnetic flux generated by the first fundamental current in the primary winding and the magnetic flux generated by the second fundamental current in the secondary winding cancel each other out, making the impedance of the magnetic balance coil in the first circuit and the second circuit zero or close to zero.

[0015] This application also provides a capacitor compensation module, including at least one reactive power compensation circuit as described in any one of the above claims.

[0016] Optionally, the capacitor compensation module includes three reactive power compensation circuits; and / or, the three reactive power compensation circuits are connected in a Y-shape or delta configuration.

[0017] Optionally, the capacitor compensation module is connected to a three-phase power supply via a switching control switch and fuses; wherein the switching control switch is used to control the connection and disconnection of the capacitor compensation module; wherein fuses are respectively installed on the three phase lines of the three-phase power supply connected to the capacitor compensation module, and the fuses are used for overcurrent protection.

[0018] This application provides a reactive power compensation circuit and a capacitor compensation module. The reactive power compensation circuit includes: a first circuit, a second circuit, and a magnetic balance coil; the magnetic balance coil includes a primary winding and a secondary winding; the first circuit includes a first capacitor connected in series with the primary winding; the second circuit includes an impedance adjustment unit connected in series with the secondary winding, the impedance adjustment unit being used to make the impedance characteristic of the second circuit capacitive when a fundamental voltage is applied, and / or to make the impedance characteristic of the second circuit in a harmonic environment in an inductive environment; the second circuit is connected to the first circuit, and is used to make the first circuit capacitive when a fundamental voltage is applied, so that the impedance of the magnetic balance coil in the first circuit decreases, thereby ensuring that the first capacitor compensates for reactive power, and / or to make the first circuit inductive when it is in a harmonic environment, so that the impedance of the magnetic balance coil in the first circuit increases, thereby suppressing harmonic current in the first capacitor. Through the technical solution of this application, the reactive power compensation circuit can utilize the capacitive and inductive impedance characteristics of the second circuit under the applied fundamental voltage and harmonic environment, respectively. This allows the magnetic balance coil to exhibit low impedance characteristics to the fundamental current in the first circuit when the fundamental voltage is applied, thus avoiding the cancellation of reactive power compensation of the first capacitor in the first circuit, thereby ensuring the reactive power compensation of the first capacitor. Conversely, it allows the magnetic balance coil to exhibit high impedance characteristics to the harmonic current in the first circuit under harmonic environment, thereby avoiding or reducing the problem of harmonic current amplification in the first capacitor due to harmonic current inflow, thus achieving a better harmonic suppression effect. Therefore, the technical solution of this application can achieve better reactive power compensation using a power capacitor (i.e., the first capacitor). Attached Figure Description

[0019] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application. To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, those skilled in the art can obtain other drawings based on these drawings without any creative effort.

[0020] Figure 1 This is a schematic diagram of the reactive power compensation circuit shown in the first embodiment of this application.

[0021] Figure 2 This is a circuit structure diagram of the reactive power compensation circuit shown in the first embodiment of this application.

[0022] Figure 3 This is a circuit diagram of the capacitor compensation circuit provided in the second embodiment of this application.

[0023] The realization of the objectives, functional features, and advantages of this application will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. The accompanying drawings have illustrated specific embodiments of this application, which will be described in more detail below. These drawings and textual descriptions are not intended to limit the scope of the concept in any way, but rather to illustrate the concepts of this application to those skilled in the art through reference to specific embodiments. Detailed Implementation

[0024] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numbers in different drawings denote the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this application. Rather, they are merely examples of apparatuses and methods consistent with some aspects of this application as detailed in the appended claims.

[0025] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, component, or apparatus that includes that element. Furthermore, components, features, and elements with the same names in different embodiments of this application may have the same meaning or different meanings, the specific meaning of which must be determined by its interpretation in that specific embodiment or further in conjunction with the context of that specific embodiment.

[0026] It should be understood that although the terms first, second, etc., may be used herein to describe various information (e.g., circuit, capacitor, etc.), this information should not be limited to these terms. These terms are only used to distinguish information of the same type from one another. For example, without departing from the scope of this document, first information may also be referred to as second information, and similarly, second information may also be referred to as first information. Depending on the context, the word "if" as used herein may be interpreted as "when," "when," or "in response to determination." Furthermore, as used herein, the singular forms "a," "an," and "the" are intended to also include the plural forms unless the context indicates otherwise. It should be further understood that the terms "comprising," "including," indicate the presence of the stated feature, step, operation, element, component, item, kind, and / or group, but do not exclude the presence, occurrence, or addition of one or more other features, steps, operations, elements, components, items, kinds, and / or groups. The terms "or," "and / or," "including at least one of the following," etc., as used in this application may be interpreted as inclusive, or mean any one or any combination thereof. For example, "including at least one of the following: A, B, C" means "any one of the following: A; B; C; A and B; A and C; B and C; A and B and C." Similarly, "A, B, or C" or "A, B, and / or C" means "any one of the following: A; B; C; A and B; A and C; B and C; A and B and C." Exceptions to this definition only occur when the combination of elements, functions, steps, or operations is inherently mutually exclusive in some way.

[0027] It should be understood that the specific embodiments described herein are merely illustrative of this application and are not intended to limit this application.

[0028] In the following description, the use of suffixes such as "module," "part," or "unit" to denote elements is solely for the purpose of illustrative purposes and has no specific meaning in itself. Therefore, "module," "part," or "unit" may be used interchangeably.

[0029] First Embodiment Reference Figure 1 and Figure 2 , Figure 1 This is a schematic diagram of the reactive power compensation circuit shown in the first embodiment of this application; Figure 2 This is a circuit structure diagram of the reactive power compensation circuit shown in the first embodiment of this application.

[0030] The reactive power compensation circuit provided in this embodiment includes: a first circuit, a second circuit, and a magnetic balance coil.

[0031] The magnetic balance coil includes a primary winding and a secondary winding.

[0032] Optionally, the terminals of the primary and secondary windings in the magnetic balance coil are reversed.

[0033] Optionally, the primary winding is a magnetic ring coil; and / or, the secondary winding is a magnetic ring coil.

[0034] The first circuit includes a first capacitor, which is connected in series with the primary winding.

[0035] The second circuit includes an impedance adjustment unit connected in series with the secondary winding. The impedance adjustment unit is used to make the impedance characteristic of the second circuit capacitive when the fundamental voltage is applied, and / or to make the impedance characteristic of the second circuit in a harmonic environment inductive.

[0036] The second circuit is connected to the first circuit and is used to be capacitive when the first circuit is subjected to a fundamental voltage, so that the impedance of the magnetic balance coil in the first circuit is reduced to ensure that the first capacitor compensates for reactive power, and / or to be inductive when the first circuit is in a harmonic environment, so that the impedance of the magnetic balance coil in the first circuit is increased to suppress the harmonic current in the first capacitor.

[0037] Optionally, the impedance adjustment unit represents any element or combination of elements capable of making the impedance characteristic of the second circuit capacitive when the fundamental voltage is applied and making the impedance characteristic of the second circuit in a harmonic environment inductive. For example, see Figure 2 An impedance adjustment unit can include an inductor and a second capacitor. Therefore, the second circuit can be an LC circuit composed of an inductor and a second capacitor, so that the impedance characteristic of the second circuit is capacitive when the fundamental voltage is applied, and inductive in a harmonic environment. Alternatively, the impedance adjustment unit can be an active circuit (e.g., an operational amplifier circuit), which can dynamically adjust the impedance characteristics of the circuit to achieve switching between capacitive and inductive impedance. Furthermore, the impedance adjustment unit can be a digital controller, which can dynamically adjust the impedance characteristics of the circuit according to a control signal to achieve switching between capacitive and inductive impedance.

[0038] Optionally, the secondary winding, inductor, and second capacitor are connected in series.

[0039] Alternatively, the inductor can be a magnetic ring coil or other conventional inductors.

[0040] In some current implementations, in the reactive power compensation method using power capacitors, reactors can be connected in series with power capacitors to suppress harmonics. A reactor is a special type of inductor, mainly used in power systems. It can be used to limit short-circuit current, regulate voltage, suppress harmonics, etc., and reactors usually have an iron core to increase inductance and magnetic flux density. When using iron core reactors in series reactors, there are the following shortcomings: (1) Due to the low permeability of the iron core, the number of turns required in the series reactor coil is large to reach the inductive reactance required for series harmonic suppression, resulting in a large reactor size; (2) Iron core reactors have high losses, and the heat generated by iron core reactors also requires special temperature control and heat dissipation, which also increases the power consumption accordingly; (3) Traditional reactors need to bear all the current. In order to avoid the saturation of the iron core, large cross-section iron cores and large cross-section wires (such as copper wires) are required, resulting in a large amount of iron cores and wires, which makes the cost much higher than that of the power capacitor itself, resulting in a significant cost inversion. Thus, the technical solution of this embodiment connects the primary winding of the magnetic balance coil in series with the first capacitor (i.e., the power capacitor), which is equivalent to replacing the traditional iron core reactor with the magnetic ring coil (which can also be regarded as a magnetic ring inductor) of the primary winding as a reactor. This can greatly reduce the size, loss and cost of the reactor. In addition, it can greatly improve the integration of the circuit, increase the power module capacity of the power system, and reduce losses.

[0041] Optionally, the range of inductance values ​​can be: ,in, This represents the inductive reactance of the inductor. This indicates the capacitive reactance value of the second capacitor.

[0042] Optionally, when the impedances of the first and second circuits are in opposite directions and the first circuit is capacitive under harmonic conditions, the value of the inductor can be... This makes the second circuit inductive, and makes the magnetic flux generated by the first harmonic current (capacitive current) in the primary winding of the first circuit and the magnetic flux generated by the second harmonic current (inductive current) in the secondary winding of the second circuit in the same direction and mutually reinforce each other, so as to increase the impedance of the magnetic balance coil to the first circuit.

[0043] Optionally, the harmonic order of the harmonic environment is k, and k ≥ 3. The harmonic order of the harmonic environment is, for example, 3rd, 5th, 7th, 11th, or 13th.

[0044] For example, since the impedances of the first circuit and the second circuit change in opposite directions under harmonic conditions, the capacitive reactance of the first capacitor in the first circuit under harmonic conditions is... It remains capacitive; the impedance of the inductor in the second circuit under harmonic conditions is... / kk* And as long as the inductive reactance value of the selected inductor is... Furthermore, when the harmonic order k is greater than 3, the impedance of the second circuit is inductive; under the same voltage conditions, the first and second circuits respectively receive the first harmonic current. Second harmonic current The first harmonic current in the magnetic balance coil Second harmonic current The generated magnetic fluxes are in the same direction and reinforce each other, and the first harmonic current of the primary winding in the magnetic balance coil... The magnetic balance coil has a relatively large first harmonic current flowing to the first capacitor in the first circuit. It exhibits the characteristics of a large series inductance, thereby suppressing the harmonic current flowing to the first capacitor.

[0045] Optionally, the impedance characteristics of the reactive power compensation circuit under harmonic conditions are as follows (electric power systems typically contain odd-order harmonics such as the 3rd, 5th, 7th, 11th, 13th, 21st, and 23rd; the following analysis uses the 3rd harmonic as an example): In the second circuit, since the impedances of the original inductor and the second capacitor are in the third harmonic state, it is sufficient that the fundamental inductance of the inductor is greater than 12% of the fundamental capacitance of the second capacitor to satisfy the following conditions: ; ; in, Represents the imaginary unit (satisfying) ), Represents angular frequency (equal to) , (50Hz), C1 represents the capacitance of the first capacitor, C2 represents the capacitance of the second capacitor, and L represents the inductance of the inductor; That is, under the third harmonic state, the second harmonic exhibits inductive properties and can be equivalent to an inductor. Harmonic current. It is a capacitive current that leads the voltage phase. 90°, harmonic current It is an inductive current that lags the voltage phase. 90°, harmonic current Harmonic current The currents are 180° apart and in opposite directions. When the primary and secondary windings are still connected in parallel on opposite sides with the same-name terminals in reverse, it is equivalent to a parallel circuit on the same side, and the current and voltage satisfy the following formulas: ① ; ② ; ③ ; in, Represents the system voltage in the circuit L represents the inductance of the coupled primary winding, and L represents the inductance of the inductor in the impedance adjustment unit. Represents the imaginary unit (satisfying) ), Represents angular frequency (equal to) , (50Hz), C1 represents the capacitance of the first capacitor, and C2 represents the capacitance of the second capacitor. It represents the mutual inductance between the primary and secondary windings (mutual inductance is the phenomenon that a change in current in one winding induces a voltage in another winding). Indicates the current phase in the circuit; Series inductance of the second circuit under the third harmonic: ④ ; when In the first case, the circuit exhibits inductive behavior. Similarly, in environments with harmonics of the third order or higher, the second circuit exhibits inductive behavior.

[0046] Optionally, the turns ratio of the primary winding to the secondary winding is set to be equal to the ratio of the first fundamental current in the first circuit to the second fundamental current in the second circuit when the fundamental voltage is applied to the first circuit. This is so that when the first fundamental current and the second fundamental current flow into the magnetic balance coil in opposite directions at their corresponding terminals, the magnetic flux generated by the first fundamental current in the primary winding and the magnetic flux generated by the second fundamental current in the secondary winding cancel each other out, making the impedance of the magnetic balance coil in the first circuit and the second circuit zero or close to zero.

[0047] In some current implementations, when using power capacitors for reactive power compensation, reactors can be connected in series with power capacitors to suppress harmonics. However, when a fundamental voltage is applied and a fundamental current flows through the power capacitors, the reactors will cancel out the actual reactive power compensation of the power capacitors (i.e., the reactors will cancel out the capacity of the power capacitors). This results in a significant reduction in the effective output capacity of the compensation equipment or circuit corresponding to the power capacitors, which is lower than the rated capacity, and consequently reduces the efficiency of the power capacitors. Thus, the technical solution of this embodiment adopts a magnetic balance coil with asymmetrical primary and secondary windings, so that when the fundamental voltage is applied to the first circuit, the ratio of the first fundamental current in the first circuit to the second fundamental current in the second circuit is equal. When the first fundamental current and the second fundamental current flow into the magnetic balance coil in opposite directions, the magnetic flux generated by the first fundamental current in the primary winding and the magnetic flux generated by the second fundamental current in the secondary winding cancel each other out, so that the impedance of the magnetic balance coil in the first and second circuits is zero or close to zero (that is, due to the cancellation effect of the magnetic circuit, the impedance of the fundamental current flowing into the first capacitor in the first circuit is zero or close to zero), thereby improving the compensation efficiency of the first capacitor (i.e., the power capacitor).

[0048] For example, the range of inductance values ​​is: When, and with the fundamental voltage applied to both the first and second circuits, the total impedance of the second circuit is... - It is capacitive, therefore, the second fundamental current in the second circuit It is a capacitive current; at this time, the second fundamental current in the second circuit... With the first fundamental current in the first circuit The phase of the fundamental voltage is 90°; the first fundamental current of the first circuit With the second fundamental current of the second circuit When the ratio of the primary winding to the secondary winding turns is equal to the turns ratio of the primary winding to the secondary winding, due to the first fundamental current... Second fundamental current The currents flowing into the same-name terminals of the magnetic balance coil are in opposite directions, and the first fundamental current... The magnetic flux and the first fundamental current generated in the primary winding The magnetic flux generated in the secondary winding is exactly equal in magnitude and opposite in direction, thus canceling each other out and achieving a state of magnetic circuit balance. The impedance of the magnetic balance coil in the first and second circuits is zero, which is equivalent to zero impedance to the fundamental current, thereby achieving the purpose of improving the compensation efficiency of the first capacitor.

[0049] Optionally, the first fundamental current in the primary winding of the magnetic balance coil ,in, Indicates the fundamental voltage. This represents the capacitive reactance of the first capacitor. Wherein, the capacitive reactance of the first capacitor... Where C1 represents the capacitance value of the first capacitor. Optionally, the second fundamental current in the primary winding of the magnetic balance coil... ,in, Indicates the fundamental voltage. This indicates the capacitive reactance value of the second capacitor. This represents the inductive reactance of the inductor. Among them, , Where C2 represents the capacitance of the second capacitor, and L represents the inductance of the inductor. The ratio of the number of turns in the primary winding to the number of turns in the secondary winding of the magnetic balance coil is 1:n. Therefore, the parameters of the first capacitor, the second capacitor, the inductor, and the transformer can be selected under the condition of the fundamental voltage ( ), determine the inductance of the matching inductor and the capacitance value of the second capacitor, so that .

[0050] Optionally, the impedance characteristics analysis of the reactive power compensation circuit under the fundamental power frequency is as follows: At the fundamental voltage ( At 50Hz, the first fundamental current in the first circuit In the capacitive circuit, the inductive reactance of the selected inductor in the second circuit is... Less than the capacitive reactance of the second capacitor The second fundamental current at that time It is also capacitive, therefore the first fundamental current Second fundamental current It is capacitive current and leads voltage. Phase 90°. When the primary and secondary windings of the magnetic balance coil are connected in parallel on opposite sides with the same-name terminals in reverse, it is equivalent to a parallel circuit on opposite sides, and the current and voltage satisfy the following formula: ① ; ② ; ③ ; in, Indicates the system voltage in the circuit. This represents the inductance of the coupled primary winding. Represents the imaginary unit (satisfying) ), Represents angular frequency (equal to) , (50Hz), C1 represents the capacitance of the first capacitor, and C2 represents the capacitance of the second capacitor. It represents the mutual inductance between the primary and secondary windings (mutual inductance is the phenomenon that a change in current in one winding induces a voltage in another winding). Indicates the phase of the current; Let the number of turns in the primary winding and the secondary winding be n1 and n2, respectively. Select appropriate values ​​for the capacitance of the first capacitor, the capacitance of the second capacitor, and the inductance of the inductor, so that the fundamental current of the circuit under the fundamental voltage satisfies: ; Substitution ① We can obtain: ④ ; In a magnetic balance coil, let the core inductance be AL: ⑤ ; ⑥ ; Alternatively, the primary and secondary windings can be in a single closed core loop. Neglecting leakage flux, the coupling factor between the primary and secondary windings is approximately 1, therefore: ⑦ ; Series inductance in the second loop: ⑧ ; If n1:n2 = 1:k, then the series inductive reactance of the primary winding in the first circuit can be made... The sum of self-inductance and mutual inductance is zero. Similarly, the series reactance of the secondary winding in the second circuit is zero. The sum of self-induction and mutual induction is also zero.

[0051] That is, the first fundamental current under the fundamental voltage. Second fundamental current The magnetic flux generated cancels each other out in the magnetic core. The primary and secondary windings present zero impedance in the first and second circuits, and do not impede the flow of current.

[0052] The reactive power compensation circuit provided in this embodiment includes: a first circuit, a second circuit, and a magnetic balance coil; the magnetic balance coil includes a primary winding and a secondary winding; the first circuit includes a first capacitor, which is connected in series with the primary winding; the second circuit includes an impedance adjustment unit connected in series with the secondary winding, the impedance adjustment unit being used to make the impedance characteristic of the second circuit capacitive when a fundamental voltage is applied, and / or to make the impedance characteristic of the second circuit in a harmonic environment in an inductive environment; the second circuit is connected to the first circuit, and is used to make the first circuit capacitive when a fundamental voltage is applied, so that the impedance of the magnetic balance coil in the first circuit decreases, thereby ensuring that the first capacitor compensates for reactive power, and / or to make the first circuit inductive when it is in a harmonic environment, so that the impedance of the magnetic balance coil in the first circuit increases, thereby suppressing the harmonic current in the first capacitor. Through the technical solution of this application, the reactive power compensation circuit can utilize the capacitive and inductive impedance characteristics of the second circuit under the applied fundamental voltage and harmonic environment, respectively. This allows the magnetic balance coil to exhibit low impedance characteristics to the fundamental current in the first circuit when the fundamental voltage is applied, thus avoiding the cancellation of reactive power compensation of the first capacitor in the first circuit, thereby ensuring the reactive power compensation of the first capacitor. Conversely, it allows the magnetic balance coil to exhibit high impedance characteristics to the harmonic current in the first circuit under harmonic environment, thereby avoiding or reducing the problem of harmonic current amplification in the first capacitor due to harmonic current inflow, thus achieving a better harmonic suppression effect. Therefore, the technical solution of this application can achieve better reactive power compensation using a power capacitor (i.e., the first capacitor).

[0053] The technical solution implemented here exhibits excellent harmonic suppression, demonstrating superior "harmonic blocking and fundamental wave passing" performance. It exhibits extremely low impedance to the fundamental frequency current, resulting in high system efficiency. Furthermore, it displays high impedance to higher-order harmonic currents, further enhancing harmonic suppression. In addition, this technical solution utilizes an auxiliary second circuit that exhibits capacitive and inductive characteristics for the fundamental frequency and third-order and higher harmonics, respectively. Through a magnetic balance coil, it achieves different impedance characteristics for the fundamental frequency and high-frequency harmonics. During normal fundamental frequency compensation, it displays low impedance to the fundamental current, while exhibiting high impedance to harmonic currents, thus achieving a better loop suppression effect.

[0054] Second Embodiment See Figure 3 , Figure 3 This is a circuit diagram of the capacitor compensation circuit provided in the second embodiment of this application.

[0055] Based on the technical concept of the above embodiments, the second embodiment of this application provides a capacitor compensation module, including at least one reactive power compensation circuit described in the first embodiment.

[0056] Optionally, the capacitor compensation module provided in this embodiment includes three reactive power compensation circuits; and / or, the three reactive power compensation circuits are arranged in a Y-shape or a delta-shape (e.g., Figure 3 (As shown) connection.

[0057] Optionally, the capacitor compensation module provided in this embodiment can be installed in a capacitor compensation circuit.

[0058] Optionally, the capacitor compensation module is connected to the three-phase power supply via a switching control switch and a fuse.

[0059] The switching control switch is used to control the activation and deactivation of the capacitor compensation module.

[0060] Among them, the three phase lines of the three-phase power supply connected to the capacitor compensation module ( Figure 3 Each of the A-phase line, B-phase line, and C-phase line in the circuit is equipped with a fuse for overcurrent protection.

[0061] The capacitor compensation module provided in this embodiment is installed in a capacitor compensation circuit, and the reactive power compensation circuit in the capacitor compensation module includes: a first circuit, a second circuit, and a magnetic balance coil; the magnetic balance coil includes a primary winding and a secondary winding; the first circuit includes a first capacitor, which is connected in series with the primary winding; the second circuit includes an impedance adjustment unit connected in series with the secondary winding, the impedance adjustment unit is used to make the impedance characteristic of the second circuit capacitive when a fundamental voltage is applied, and / or to make the impedance characteristic of the second circuit in a harmonic environment in an inductive manner; the second circuit is connected to the first circuit, and is used to make the first circuit capacitive when a fundamental voltage is applied, so that the impedance of the magnetic balance coil in the first circuit is reduced, thereby ensuring that the first capacitor compensates for reactive power, and / or in the first circuit When in a harmonic environment, the magnetic balance coil exhibits inductive impedance, increasing its resistance in the first circuit to suppress harmonic currents in the first capacitor. Therefore, the reactive power compensation circuit can utilize the capacitive and inductive impedance characteristics of the second circuit under fundamental voltage and harmonic conditions, respectively. This allows the magnetic balance coil to exhibit low impedance to the fundamental current in the first circuit when the fundamental voltage is applied, preventing the cancellation of reactive power compensation from the first capacitor and ensuring the first capacitor compensates for reactive power. Alternatively, it can make the magnetic balance coil exhibit high impedance to the harmonic current in the first circuit under harmonic conditions, avoiding or reducing the amplification of harmonic currents in the first capacitor due to harmonic current inflow, thus achieving better harmonic suppression. Therefore, the capacitor compensation module provided by this embodiment can better compensate for reactive power in the power system to prevent power system degradation.

[0062] In this application, the descriptions of the various embodiments have different focuses. For parts that are not described in detail or recorded in a certain embodiment, please refer to the relevant descriptions of other embodiments.

[0063] The technical features of the present application can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of the present application.

[0064] The above are merely preferred embodiments of this application and do not limit the patent scope of this application. Any equivalent structural or procedural transformations made using the content of this application's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of this application.

Claims

1. A reactive power compensation circuit, characterized by, include: First circuit, second circuit, and magnetic balance coil; The magnetic balance coil includes a primary winding and a secondary winding, wherein the terminals of the primary winding and the secondary winding are reversed. The first circuit includes a first capacitor, and the first capacitor is connected in series with the primary winding; The second circuit includes an impedance adjustment unit connected in series with the secondary winding. The impedance adjustment unit is used to make the impedance characteristic of the second circuit capacitive when a fundamental voltage is applied, and / or to make the impedance characteristic of the second circuit in a harmonic environment inductive. The impedance adjustment unit includes one of the following: an LC circuit composed of an inductor and a second capacitor, an operational amplifier circuit, and a digital controller. The second circuit is connected to the first circuit and is used to be capacitive when the fundamental voltage is applied to the first circuit, so that the impedance of the magnetic balance coil in the first circuit is reduced to ensure that the first capacitor compensates for reactive power, and / or to be inductive when the first circuit is in the harmonic environment, so that the impedance of the magnetic balance coil in the first circuit is increased to suppress the harmonic current in the first capacitor.

2. The reactive power compensation circuit of claim 1, wherein, When the impedance adjustment unit is the LC circuit, the secondary winding, the inductor of the LC circuit, and the second capacitor of the LC circuit are connected in series.

3. The reactive power compensation circuit of claim 2, wherein, The inductor is a magnetic ring coil.

4. The reactive power compensation circuit according to claim 1 or 2, characterized in that, The primary winding is a magnetic ring coil; and / or, The secondary winding is a magnetic ring coil.

5. The reactive power compensation circuit of claim 2, wherein, The inductance is in the range of: wherein, represents the inductive value of the inductance, represents the capacitive value of the second capacitance; Wherein, under the harmonic environment, the impedances of the first circuit and the second circuit are in opposite directions and the first circuit is capacitive, the value of the inductor is... This makes the second circuit inductive, and makes the magnetic flux generated by the first harmonic current of the first circuit in the primary winding and the magnetic flux generated by the second harmonic current of the second circuit in the secondary winding in the same direction and mutually reinforce each other, so as to increase the impedance of the magnetic balance coil to the first circuit. Wherein, the first harmonic current is a capacitive current, and the second harmonic current is an inductive current.

6. The reactive power compensation circuit of claim 5, wherein, The harmonic order of the harmonic environment is k, and k≥3.

7. The reactive power compensation circuit of claim 1 or 2, wherein, The turns ratio of the primary winding to the secondary winding is set to be equal to the ratio of the first fundamental current in the first circuit to the second fundamental current in the second circuit when a fundamental voltage is applied to the first circuit. This ensures that when the first fundamental current and the second fundamental current flow into the magnetic balance coil in opposite directions at their corresponding terminals, the magnetic flux generated by the first fundamental current in the primary winding and the magnetic flux generated by the second fundamental current in the secondary winding cancel each other out, resulting in zero or near-zero impedance of the magnetic balance coil in the first and second circuits.

8. A capacitance compensation module, characterized by It includes at least one reactive power compensation circuit as described in any one of claims 1 to 7.

9. The capacitance compensation module of claim 8, wherein, Includes the three aforementioned reactive power compensation circuits; and / or, The three reactive power compensation circuits are connected in a Y-shape or a delta-shape.

10. The capacitance compensation module of claim 9, wherein, The capacitor compensation module is connected to a three-phase power supply via a switching control switch and a fuse. The switching control switch is used to control the activation and deactivation of the capacitor compensation module; The three phase lines of the three-phase power supply connected to the capacitor compensation module are each equipped with a fuse, which is used for overcurrent protection.

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