Method for adjusting the ratio of active and reactive power consumption
A resonant oscillatory circuit with a three-phase current choke and delta-connected capacitors addresses inefficiencies in existing methods by providing flexible and efficient reactive power regulation, reducing active energy use and maintaining optimal P/Q ratio.
Patent Information
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- NAM ALEKSANDR KLIMENTEVICH
- Filing Date
- 2025-07-25
- Publication Date
- 2026-05-21
Smart Images
Figure RU2025050226_21052026_PF_FP_ABST
Abstract
Description
[0001] A method for regulating the ratio of active and reactive power consumption in three-phase circuits
[0002] AREA OF TECHNOLOGY
[0003] The invention relates to the field of electrical engineering, in particular to converter technology, and can be used to compensate for reactive power in three-phase electric power networks of 0.4 kV consumers.
[0004] PRIOR ART
[0005] The vast majority of consumer electrical installations today are powered by three-phase AC networks. Variable voltage and current are necessary to transform the parameters of transmitted electricity and supply power to geographically remote regions and consumers with relatively low process losses.
[0006] In this case, the entire electrical network is divided into a series of galvanically isolated sections, with only electromagnetic coupling between the windings of the step-up or step-down transformers. Each of these sections is essentially a separate RLC oscillatory circuit.
[0007] The capacitive component of such an RLC circuit is primarily contributed by the power lines, the inductive component by the windings of transformers and electric motors, and the active component by the ohmic resistance of network elements and the purely active load of consumers. These capacitive and inductive elements are considered reactive and can be saturated with energy and then released back into the grid.
[0008] This portion of the energy does not go toward the useful operation of consumer devices and mechanisms and, therefore, is not consumed. Therefore, the portion of the energy exchanged between the capacitive and inductive elements of a network section to saturate is called reactive.
[0009] The share of reactive energy per unit of time is controlled by the parameter tangent of angle phi (tg φ), equal to the ratio of reactive power to active power, where φ is the angle between the vectors of apparent and active power.
[0010] The methods currently used to regulate the ratio of active and reactive power consumption have a number of drawbacks. The most common method is the use of static capacitor banks. This method lacks flexibility under variable load conditions and can lead to deterioration in the operating conditions of electrical consumers.
[0011] Another widely accepted method for precisely regulating the ratio of active and reactive power consumption is the use of synchronous compensators. Their widespread use is limited by the relatively high cost and complexity of operating rotating equipment, especially in extended power systems with numerous power supply centers.
[0012] Also known from the prior art, in particular from patent RU 197031 Ш, IPC class H02M 7 / 155, published March 26, 2020, is a method for regulating the ratio of active and reactive power consumption in three-phase circuits. This method utilizes a half-wave generator containing a three-phase steel-coiled inductor, a load, thyristors, and capacitors. In this half-wave generator, delta-connected capacitors are connected in parallel to a three-phase AC source, to which a three-phase steel-coiled inductor, other delta-connected capacitors, star-connected capacitors, and a load are also connected in parallel via thyristors.
[0013] A drawback of the known solution is the flow of direct current from the neutral of the three-phase inductor to the neutral of the supply power transformer, which causes magnetization of the low-voltage windings of the supply power transformer. Another drawback of the known technical solution is the lack of coordination between the reactive power in the load circuit and the capacitance of the connected capacitors, which reduces the efficiency of regulating the ratio of active and reactive power consumption in three-phase circuits.
[0014] Thus, the technical problem is to create an effective method for regulating the ratio of active and reactive power consumption in three-phase circuits.
[0015] DISCLOSURE OF THE INVENTION
[0016] The proposed invention is based on the task of creating a method that ensures an increase in the efficiency of regulating the ratio of active and reactive power consumption in three-phase circuits, expressed in an improvement in the ratio of active and reactive power at the terminals of the consumer's electrical receivers, as well as in reducing the volume of active electrical energy consumed from the network, without changing the operating mode of the consumer's electrical receivers.
[0017] The proposed solution to the stated problem is that at least one block of capacitors connected in a triangle is connected in parallel to the electrical load, and a resonant oscillatory circuit consisting of a three-phase current choke with a star connection of the windings and at least one block of capacitors connected in a triangle, connected in parallel to each other, is connected through at least one power semiconductor switch, while the neutral of the three-phase current choke is connected to the neutral of the supply transformer through a rheostat with variable resistance, the values of phase currents and voltages in the load circuit are measured, as well as the angles between the vectors of phase currents and voltages, and a control signal is generated to connect at least one block of capacitors.Connection to an electrical load of a resonant oscillatory circuit consisting of a three-phase current choke with a star connection of windings and at least one block of capacitors connected in a triangle, connected in parallel to each other, is necessary to enable the accumulation of energy in the capacitors and its release to the load with a delay using at least one power semiconductor switch.
[0018] Connecting at least one block of capacitors connected in a triangle, placed before the semiconductor switch, in parallel to the electrical load makes it possible to regulate the amount of reactive power while registering a constant active load and an increase in the amount of reactive power.
[0019] Measuring the magnitude of phase currents and voltages in the load circuit, as well as the angles between the vectors of phase currents and voltages, and generating a control signal to connect at least one block of capacitors is necessary to be able to connect at least one block of capacitors that store the reactive component of electrical energy and discharge it into the consumer load.
[0020] Any device known from the prior art can be used as a voltage and current control unit, in particular, the voltage, current and power measuring converter for three-phase electrical networks фе1892-а (https: / / vibralor.nt- 11,П / 1И^4Кек / тащщ / / Е1892-АР,рйГ), the Micrologic А Е 2014.pdf control and management unit (promeiteh.ru).
[0021] A three-phase current choke with windings connected in a star and at least one block of capacitors connected in a triangle constitute an oscillatory circuit, where the three-phase current choke is an inductance, and at least one block of power capacitors is a capacitance.
[0022] The presence of power semiconductor switches, through which a three-phase current choke with star-connected windings and at least one delta-connected capacitor bank are connected in parallel, is necessary to ensure current flow to the oscillatory circuit in the open semiconductor switch mode and current flow in the reverse direction—in the closed semiconductor switch mode. Diodes or thyristors can be used as power semiconductor switches in this case.
[0023] A comparison of the proposed method allows us to conclude that it meets the "novelty" criterion, as it offers a new method for regulating the ratio of active and reactive power in three-phase circuits, a method previously unknown in the prior art. Specifically, it utilizes a resonant oscillatory circuit consisting of a three-phase inductor with star-connected windings and delta-connected capacitor banks connected via power semiconductor switches and a rheostat in the neutral. The proposed method differs from known solutions such as static capacitor banks or synchronous compensators.
[0024] The proposed method, thanks to a combined resonant circuit structure that creates a controlled oscillatory circuit with two types of reactive elements, allowing for flexible power regulation; connection of the choke neutral via a rheostat, which eliminates magnetization of the transformer windings (a problem with analog systems) and allows for regulation of the neutral current, improving phase balancing; and a measurement-based control algorithm, which enables automatic adjustment to changing loads and precise maintenance of the P / Q ratio, collectively solves specific problems of reactive power over / undercompensation and losses due to transformer magnetization.
[0025] This allows us to conclude that the claimed invention meets the criterion of "inventive step." The claims are drafted without dividing them into limiting and distinguishing parts to better understand the essence of the claimed method and more accurately present the essence of the claimed technical solution.
[0026] BEST OPTIONS FOR IMPLEMENTING THE INVENTION
[0027] The claimed method is illustrated by the following examples of specific implementation, but is not limited to them.
[0028] Fig. 1 shows a diagram of a device intended for use in a method for regulating the ratio of active and reactive power consumption in three-phase circuits.
[0029] Fig. 2 shows a graph of the consumer load for active and reactive power (power profile).
[0030] The reactive power compensator comprises a housing in which a voltage and current control unit 1 is located, as well as at least one block of capacitors 2 connected in a triangle, configured to be connected in parallel to an electrical load 6.
[0031] The resonant oscillatory circuit is equipped with a set of relays 8-10, with the help of which the voltage and current control unit 1 controls the amount of reactive component of power in the load circuit and elements, connecting and disconnecting the required number of capacitor blocks 3-5, respectively.
[0032] Capacitor blocks 2-5 represent stages, and each stage is equipped with a set of switching devices, in particular, relays 7-10 for the possibility of connecting and disconnecting them from the circuit in order to control the amount of reactive power in the load circuit.
[0033] The equivalent reactive power of the three-phase current choke 11 is selected equal to the maximum reactive power in the network, and the total equivalent reactive power of the capacitor blocks 3-5 is less than or equal to the equivalent reactive power of the three-phase current choke 11.
[0034] The three-phase current choke 11 with a star connection of windings consists of three windings located on a magnetic circuit.
[0035] A three-phase current choke 11 with a star connection of windings and at least one block of capacitors 3-5 connected in a triangle are designed with the possibility of being connected to an electrical load 6 through at least one power semiconductor switch 12 in parallel to each other.
[0036] In this case, the neutral of the three-phase current choke 11 is designed with the possibility of connecting to the neutral of the supply transformer 13 through a rheostat 14 with variable resistance.
[0037] The device's housing is grounded (the grounding point is shown in the drawing at position 15). The device is designed for operation in three-phase 0.4 kV networks.
[0038] Voltage and current monitoring unit 1 contains a microcontroller that controls the measurement process and all functional units. It also implements measurement and control algorithms in accordance with a specialized program stored in its internal program memory. The units are controlled via hardware and software interfaces implemented on the microcontroller's input / output ports. Measurements are performed using a multichannel analog-to-digital converter (ADC) integrated into the microcontroller.
[0039] The automated voltage and current meter samples instantaneous voltage and current values in parallel across six analog channels. The microcontroller uses these instantaneous voltage and current samples to calculate average values for frequency, voltage, current, active, apparent, and reactive power in each phase of the network over the entire period. The proposed method for regulating the ratio of active and reactive power consumption in three-phase circuits is implemented as follows.
[0040] At least one block of capacitors 2 connected in a triangle is connected in parallel to the electrical load 6, and a resonant oscillatory circuit consisting of a three-phase current choke 11 with a star connection of the windings and at least one block of capacitors 3-5 connected in a triangle, connected in parallel to each other, is connected through at least one power semiconductor switch 12.
[0041] In this case, the neutral of the three-phase current choke 11 is connected to the neutral of the supply transformer 13 through a rheostat 14 with variable resistance.
[0042] Using the voltage and current control unit 1, the values of phase currents and voltages in the load circuit are measured, as well as the angles between the vectors of phase currents and voltages, the hourly load graph of the consumer for active and reactive power is recorded (Fig. 2), the median load for active and reactive power is calculated, and the peaks of active and reactive power are recorded.
[0043] Following this, the microcontroller of voltage and current monitoring unit 1 generates a control pulse and, using relays 8-10, connects or disconnects capacitor blocks 3-5, located downstream of power semiconductor switches 12, simultaneously proportionally increasing or decreasing the resistance of rheostat 14 in the neutral, respectively. When voltage and current monitoring unit 1 registers a constant active load and an increase in reactive power, voltage and current monitoring unit 1 connects capacitor blocks 2, located upstream of power semiconductor switches 12, using relay 7, without changing the resistance of rheostat 14 in the neutral. The method is based on accumulating energy in capacitors and releasing it to the load with a delay due to the blocking of power semiconductor switch 12, implemented as a diode or thyristor.The delay is achieved by connecting at least one delta-connected capacitor bank 3-5 to load 6 with a star-connected phase configuration. The effect of power transfer to the grid is also ensured by the presence of a three-phase choke 11 in the circuit.
[0044] If tg φ exceeds unity, then the excess reactive power is compensated by capacitor blocks 2 (capacitive elements) at the input of the connected oscillatory circuit.
[0045] The electrical power supplied to the load should be between 10% and 60% of the actual load power consumption. The equivalent reactive power of the choke should not exceed 40% of the supply transformer's full power.
[0046] Below is an example of the implementation of a method for regulating the ratio of active and reactive power consumption in three-phase circuits.
[0047] The hourly schedule of the consumer load for active and reactive power is recorded, with active power being measured in kilowatts (kW), and reactive power in kilovolt-amperes reactive (kV Amp), Fig. 2.
[0048] The median load A+ is determined to be 58 kW and R+ to be 37 kVAr. The peak active and reactive power values are recorded at 72.8 kW and 44.8 kVAr, respectively.
[0049] The parameters of inductance and capacitors are selected based on reactive power. Manufacturers of chokes and capacitors typically specify the reactive power they correspond to, so it is sufficient to select a power equal to or slightly greater than the median reactive power recorded by the power profile (Fig. 2).
[0050] In this case, the reactive power in the load circuit is related to the values of inductance and capacitance by the following relationships:
[0051]
[0052] Where
[0053] I - load current, A;
[0054] X is the reactance of the choke or capacitor, Ohm / is the current frequency, equal to 50 Hz
[0055] L - choke inductance, H
[0056] C is the total capacitance of capacitors, F.
[0057] The parameters of power semiconductor switches 12 are selected based on the nominal current, equal to three times the current / flowing in the load.
[0058] The number of capacitor blocks 2-5 (regulation stages) depends on the set of capacitors and can vary from 2 to 10.
[0059] Capacitor banks are connected so that the power of the connected capacitors corresponds as closely as possible to the current reactive power of the load. The greater the number of stages, the more accurate the regulation.
[0060] If the reactive power in the load (kVAr) numerically exceeds the value of the active power (kW), then the difference between the active and reactive powers is compensated by capacitor blocks 2, connected before the power semiconductor switches 12.
[0061] An example of the operation of a reactive power compensator with a three-phase current choke of 100 kV Ar and a capacity of 20 kV Ar capacitors.
[0062]
[0063]
[0064] The resistance of the rheostat in the neutral changes proportionally to the current flowing in the neutral, based on the ratio of 10 ohms for every 1 ampere of current.
[0065] The efficiency of using a reactive power compensator is assessed by reducing the consumption of active electrical energy from the network while maintaining the standard value of tg f < 0.4.
[0066] INDUSTRIAL APPLICABILITY: The invention meets the industrial applicability criteria, as it can be implemented using standard components (capacitors, chokes, semiconductor switches, rheostats) and is applicable in three-phase 0.4 kV networks. The description includes specific implementation examples, a calculation method, and proof of effectiveness, confirming the feasibility of practical application.
Claims
Invention formula 1. A method for regulating the ratio of active and reactive power consumption in three-phase circuits, which consists in connecting at least one block of capacitors connected in a triangle in parallel to the electrical load, and also connecting a resonant oscillatory circuit through at least one power semiconductor switch, consisting of a three-phase current choke with a star connection of windings and at least one block of capacitors connected in a triangle, connected in parallel to each other, wherein the neutral of the three-phase current choke is connected to the neutral of the supply transformer through a rheostat with variable resistance, measuring the values of phase currents and voltages in the load circuit, as well as the angles between the vectors of phase currents and voltages, and generating a control signal for connecting at least one block of capacitors.