Power control device and method

Abstract

A power control device for modulating a power signal and a method for modulating a power signal are discussed. In one example, the power control device comprises a magnetic core with a first limb and a second limb. A primary winding is disposed around the first limb and a secondary winding is disposed around the second limb. The power control device comprises a voltage source converter having an AC connection and a DC connection, and a controller. The controller is configured to receive data related to a parameter of a first signal in the primary winding, compare the parameter of the first signal to a parameter of a reference signal for the secondary winding, and determine a harmonic signal that, when applied to the first limb, causes the second signal in the secondary winding to approximate the reference signal. The controller is configured to cause the harmonic signal to be applied to the first limb using the voltage source converter.

Description

[Technical field]

[0001] The following disclosure relates to a power control device for modulating a power signal and a method for modulating a power signal.

[0002]

[0002] To maintain a reliable utility power supply, the voltage and frequency of the power grid must be maintained within target ranges. Generally, electricity must be consumed as it is generated, and therefore supply and demand must be balanced to maintain the target voltage and frequency of the electrical network.

[0003]

[0003] Electricity load balancing typically involves a variety of techniques such as adjusting the output of dispatchable generation, i.e., power sources that can be dispatched on demand according to the demands of the power grid operator, such as fossil fuel-based power plants. Another example that aids in load balancing is the employment of pumped hydroelectric generation to store energy in the form of gravitational potential energy.

[0004]

[0004] The generation of non-dispatchable renewable energy sources, such as wind and solar power, cannot be easily controlled by grid operators. The increasing penetration of such non-dispatchable renewable energy sources increasingly poses challenges to load balancing and therefore frequency stability. For example, solar power generation occurs throughout the day, creating a timing imbalance between peak demand and energy production, commonly referred to as the duck curve.

[0005]

[0005] An imbalance between power generation and consumption can lead to energy losses and instabilities in the power grid due to waveform harmonics and voltage deviations, and ultimately to potential system failures in the form of power outages.

[0006]

[0006] The power controller disclosed herein enables optimization of work and energy flow in time, space, and mode through time-varying magnetic flux modulation by near-field induction and fast dispatch. Such a power controller can thus be used to aid in load balancing, power flow, and quality optimization.

[0007]

[0007] A power control device is provided. The power control device comprises a magnetic core with a first limb, a second limb, and a third limb. Each limb is disposed about a central axis, each limb having a first end and a second end, the first ends of the limbs being connected to each other at a first location along the central axis, and the second ends of the limbs being connected to each other at a second location along the central axis. A primary winding may be disposed about the first limb, and a first secondary winding may be disposed about the first limb. A second secondary winding may be disposed about the second limb, and a third secondary winding may be disposed about the third limb. The power control device comprises a voltage source converter having an AC connection and a DC connection, and a controller. The controller is configured to receive data relating to a parameter of a first signal in the primary winding, compare the parameter of the first signal to parameters of respective reference signals for each of the second and third secondary windings, and determine a harmonic signal that causes a respective second signal in each of the second and third secondary windings to approximate a respective reference signal when the harmonic signal is applied to the first limb. The controller is configured to cause the harmonic signal to be applied to the first limb using a voltage source converter.

[0008]

[0008] The power control device modulates, for example, a power signal in a utility electric system. For example, the reference signal may have a frequency of 50 Hz or 60 Hz. The parameters of the first signal may include one or more of a voltage, a current, a frequency, a phase angle, and a power factor of the first signal.

[0009]

[0009] The AC connection of the voltage source converter may be electrically coupled to the primary winding, and the controller may be configured to cause the voltage source converter to apply the harmonic signal to the first limb by causing the voltage source converter to apply the harmonic signal to the primary winding. The AC connection of the voltage source converter may be electrically coupled to a tap along the primary winding. Instead of a tap, the power control device may include a modulation winding disposed about the first limb. Instead of a connection between the voltage source converter and the primary winding, the AC connection of the voltage source converter may be electrically coupled to the modulation winding, and the controller may be configured to cause the voltage source converter to apply the harmonic signal to the first limb by causing the voltage source converter to apply the harmonic signal to the modulation winding. Thus, the voltage source converter is electromagnetically coupled to the primary winding via the modulation winding. By applying the harmonic signal into a tap in the primary winding rather than the modulation winding, the amount of copper required for the winding is reduced, and copper losses during operation of the power control device are reduced. Furthermore, a configuration having a tap in the winding requires less surface area of ​​the magnetic core to induce the harmonic signal than a separate modulation winding.

[0010]

[0010] The voltage source converter may be a first voltage source converter, and the power control device may include a second voltage source converter having an AC connection and a DC connection. In other words, there may be a voltage source converter electrically coupled to each of the primary and secondary windings. The AC connection of the second voltage source converter may be electrically coupled to the second secondary winding. For example, the second voltage source converter may be electrically coupled to a tap along the second secondary winding. Instead of a tap, the AC connection of the second voltage source converter may be electrically coupled in parallel to a load electrically coupled to the second secondary winding. Instead of a connection between the voltage source converter and the primary and secondary windings, the power control device may include a second modulation winding disposed around the limb, and the AC connection of the second voltage source converter may be electrically coupled to the second modulation winding. Thus, the voltage source converter is electromagnetically coupled to each of the primary and secondary windings through the modulation winding. The symmetrical arrangement of the components on each side of the magnetic core allows for stabilization of the signal frequency through application of voltage droop control. This in turn allows achieving a temporary balance of demand (load) against supply in real time, even in the presence of negative power flows and highly non-linear loads on both sides of the power controller.

[0011]

[0011] The power control device may comprise an energy storage means. The energy storage means may be coupled to the DC connection of the voltage source converter. The energy storage means may store electrical energy, for example, in a capacitor or a battery. The energy storage means may convert energy into different forms, such as rotational energy in a flywheel, or thermal energy to a thermal energy storage device or a heat pump. The energy storage means may convert electrical energy to electrolyze water into hydrogen and oxygen, each of which may be stored as fuel. The energy stored in the energy storage means may be released at a later time, for example during peaks of demand in the utility electric system. Thus, the energy storage means may comprise one or more of a capacitor, a battery, a flywheel, a thermal energy storage device, for example an electrolyzer with a coupled hydrogen storage unit, for example a heat pump with a coupled thermal energy storage device, and for example an air compressor with a coupled air tank. If the power control device comprises a second voltage source converter, the energy storage means may also be coupled to the DC connection of the second voltage source converter. The energy storage means allows for temporary shifting of power, i.e. storing energy for load balancing.

[0012]

[0012] The magnetic core may have a toroidal shape. The primary winding may be a first primary winding, and the power control device may include a second primary winding disposed about the second limb and a third primary winding disposed about the third limb. Each of the first primary winding, the second primary winding, and the third primary winding may be configured to carry a different phase of the three-phase AC signal.

[0013]

[0013] The harmonic signals may approximate the second signals in each of the second and third secondary windings to the respective reference signals by compensating for harmonics in the first signals, such that the harmonics are eliminated or reduced in the respective second signals. The phase of the respective second signals may be locked to the phase of the first signal using a phase-locked loop. The approximation of the respective reference signals by the respective second signals may include matching or substantially matching parameters of the reference signals.

[0014]

[0014] The harmonic signal can cause the magnitude of the current in each of the first primary winding, the second primary winding, and the third primary winding to be evenly redistributed between the first primary winding, the second primary winding, and the third primary winding.

[0015]

[0015] The voltage source converter may comprise silicon carbide metal oxide semiconductor field effect transistors and / or gallium nitride transistors. The voltage source converter may have a switching speed faster than the periodic duration, i.e., frequency, of the reference signal itself. For example, the voltage source converter may have a switching speed of 1 / 100th to 1 / 500th of a second.

[0016] A computer-implemented method is provided for modulating a respective second signal in each of a second secondary winding and a third secondary winding of a power control device having a magnetic core with a first limb, a second limb, and a third limb. A primary winding may be disposed about the first limb, and a first primary winding may be disposed about the first limb. A second secondary winding may be disposed about the second limb, and a third secondary winding may be disposed about the third limb. Each of the first limb, second limb, and third limb is an arc-shaped limb, each limb is disposed about a central axis, each limb has a first end and a second end, the first ends of the limbs are connected to each other at a first location along the central axis, and the second ends of the limbs are connected to each other at a second location along the central axis. The method includes receiving data relating to a parameter of a first signal in the primary winding; comparing the parameter of the first signal to a parameter of a respective reference signal for each of the second secondary winding and the third secondary winding; determining a harmonic signal that causes a respective second signal in each of the second secondary winding and the third secondary winding to approximate a respective reference signal when the harmonic signal is applied to the first limb; and applying the harmonic signal to the first limb using a voltage source converter.

[0017]

[0017] Applying the harmonic signal to the first limb using a voltage source converter may include applying the harmonic signal to a primary winding using a voltage source converter. Applying the harmonic signal to the primary winding using a voltage source may include applying the harmonic signal to a tap in the primary winding using a voltage source converter.

[0018]

[0018] The step of applying the harmonic signal to the first limb using a voltage source converter may include a step of applying the harmonic signal to a modulation winding using a voltage source converter, the modulation winding being disposed around the first limb.

[0019]

[0019] The harmonic signals cause the respective second signals in each of the second and third secondary windings to approximate the respective reference signals by compensating for harmonics in the first signal, so that harmonics are eliminated or reduced in the respective second signals, i.e., by destructive interference. [Brief description of the drawings]

[0020] Further details, aspects and embodiments of the present invention will now be described, by way of example only, with reference to the drawings in which elements are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For ease of understanding, like reference numerals have been included within the respective figures. [Figure 1] FIG. 1 is a schematic diagram of a power control device. [Diagram 2] FIG. 2 is a schematic diagram of a power control device. [Diagram 3] FIG. 3 is a schematic diagram of a power control device. [Figure 4] FIG. 4 is a schematic diagram of a power control device. [Diagram 5] FIG. 5 is a schematic diagram of a power control device. [Figure 6] FIG. 6 is a schematic diagram of a power control device. [Figure 7] FIG. 7 is a schematic diagram of a power control device. [Figure 8] FIG. 8 is a schematic diagram of a power control device. [Figure 9A] FIG. 9A is a schematic diagram of a magnetic core. [Figure 9B] FIG. 9B is a schematic side view of the magnetic core of FIG. 9A. [Figure 9C] FIG. 9C is a schematic top view of the magnetic core of FIG. 9A. [Figure 10] FIG. 10 is a schematic diagram of a power control device. [Figure 11] FIG. 11 is a schematic diagram of a power control device; and [Figure 12] FIG. 12 is a flow chart of a method for modulating a power signal. Detailed Description

[0021]

[0021] The present disclosure relates to a power control device and method that includes receiving input electrical energy in the form of an input signal having a voltage waveform and a root mean square (RMS) voltage, and applying a harmonic signal to output electrical energy in the form of an output signal having a desired voltage waveform and a desired output RMS voltage. For example, the waveform of the input signal may include noise and harmonic distortion that are suppressed in the output signal.

[0022]

[0022] Referring to Figure 1, the power control device 100 comprises a magnetic core 102 having a primary limb 104 and a secondary limb 106. The magnetic core 102 may be linear or toroidal in shape. The primary limb 104 includes a primary winding 110 electrically coupled to an alternating current (AC) power source 112. The secondary limb 106 includes a secondary winding 116 electrically coupled to a load 118. The load 118 may be one or more downstream loads that draw power from the power control device 100. In the figure, the load 118 is shown as an ideal resistor. Hereinafter, the magnetic core 102 together with the primary winding 110 and the secondary winding 116 are collectively referred to as an electromagnetic subsystem.

[0023]

[0023] The power control device 100 includes a voltage source converter 124 configured to function both as a converter to convert power from AC to direct current (DC) and as an inverter to convert power from DC to AC. The voltage source converter 124 includes a plurality of transistors and a plurality of capacitors. One exemplary form of a known voltage source converter includes a multilevel converter arrangement. The multilevel converter arrangement includes a converter bridge or cells connected in series, with each converter cell including a pair of series-connected transistors connected in parallel to a capacitor. The transistors may be silicon carbide-based metal oxide semiconductor field effect transistors, insulated gate bipolar transistors, and / or gallium nitride transistors. The AC terminals of the voltage source converter 124 are electrically coupled to a tap 128 in the primary winding 110. The DC terminals of the voltage source converter 124 are electrically coupled to an energy storage means 130. In FIG. 1, the energy storage means 130 is shown as a capacitor. Other exemplary energy storage means are discussed below.

[0024] The power control device 100 includes a bridge rectifier 134 configured to convert power from AC to DC. The AC terminals of the bridge rectifier 134 are electrically coupled in parallel to the load 118. The DC terminals of the bridge rectifier 134 are electrically coupled to the energy storage means 130.

[0025] When an electrical signal from an AC power source 112 is introduced to the primary winding 110, an electromagnetic field is induced in the magnetic core 102. The electromagnetic field induces an electrical signal in the secondary winding 116. The number of turns of the windings of the primary winding 110 and the secondary winding 116 can be the same so that the voltage of the input electrical signal and the voltage of the output electrical signal are the same. In another example, the secondary winding 116 can have fewer turns than the primary winding 110 so that the output voltage is stepped down. In another example, the secondary winding 116 can have more turns than the primary winding 110 so that the output voltage is stepped up.

[0026]

[0026] Power control device 100 includes a controller 140 that may be communicatively coupled to voltage source converter 124. Controller 140 is configured to receive data related to parameters of an input electrical signal in primary winding 110. For example, the parameters may include voltage, current, frequency, phase angle, and / or power factor. The controller may receive data from one or more voltage and / or current sensors.

[0027]

[0027] The controller 140 is configured to compare parameters of the input signal to parameters of a reference signal for the secondary winding 116. The reference signal includes, for example, an ideal waveform having desired parameters of an output signal free of noise or harmonics. The controller 140 is configured to determine a harmonic signal that, when applied to the primary winding 110, causes the output electrical signal in the secondary winding 116 to approximate the reference signal, for example, by destructive interference. The controller 140 is configured to apply the harmonic signal to the primary winding 110 using the voltage source converter 124. Thus, when the harmonic signal is applied, the output electrical signal in the secondary winding 116 is substantially identical to the reference signal.

[0028]

[0028] The energy balance in the electromagnetic subsystem at time t1 for a signal is given by: E P (t1)=E S (t1)-L(t1)

[0029]

[0029] In the formula, E P and E S denote the primary and secondary energy, respectively. L denotes the energy loss occurring throughout the electromagnetic subsystem and can be expressed as: L(t1)=L SI (t1)+L EMS (t1)

[0030]

[0030] L SI represents the loss due to signal inequality between the primary and secondary, LEMS denotes the typical electromagnetic losses in the electromagnetic subsystem, for example due to eddy current losses or stray losses. L SI can account for a significant proportion of the total energy losses, especially in the presence of nonlinear loads on the primary side, which can be caused by high-order harmonic content in the primary current and phase shifts between the input and output signals.

[0031]

[0031] By applying a harmonic signal, L SI Recovery of the given time increment Δt1, L SI The energy recovered within (t1+Δt1) may be buffered in multiple capacitors of the voltage source converter 124. The time increment Δt1 is smaller than the periodic duration of the reference signal, for example, smaller than 1 / 50 or 1 / 60 seconds. For example, Δt1 may be 1 / 100 to 1 / 500 seconds.

[0032]

[0032] A portion of the energy buffered in the capacitors can be used to provide power for applying the harmonic signal at a later time t2, thereby supporting power factor correction, voltage regulation, power quality management, and / or phase balancing as part of the system frequency stabilization of the output signal. Furthermore, the energy buffered in the capacitors can be transferred to the energy storage means 130. The energy storage means 130 can store the electric energy, for example, in a capacitor or a battery. The energy storage means 130 can convert the energy into different forms, such as rotational energy in a flywheel, or thermal energy for a thermal energy storage device or a heat pump. In a particular example, the electric energy can be used to electrolyze water into hydrogen and oxygen, each of which can be stored as fuel. The energy stored in the energy storage means 130 can be released at a later time, for example, during a peak in demand in a utility electric system. Thus, the power control device enables optimization of work and energy flows in time, space, and mode, enabled by time-varying flux modulation with near-field induction and fast dispatch.

[0033]

[0033] Furthermore, by appropriately sizing the capacitors of voltage source converter 124 so that the capacitors and / or energy storage means 130 are capable of storing more electrical energy than is required to apply the harmonic signal, i.e., approximately 20% of the total power rating of the electromagnetic subsystem, it becomes possible to draw electrical energy from the secondary side of the electromagnetic subsystem into voltage source converter 124, for example, during periods of surplus energy generation in the commercial electrical system.

[0034]

[0034] Although the above discussion has been made with reference to power controller 100, various configurations of the power controller will function similarly to enable modulation of the power signal. A selection of these configurations are discussed below.

[0035] 2, the power controller 200 includes a magnetic core 102 having a primary limb 104 and a secondary limb 106. The primary limb 104 includes a primary winding 110 electrically coupled to an AC power source 112. The primary limb 104 also includes a modulation winding 202. The secondary limb 106 includes a secondary winding 116 electrically coupled to a load 118. The power controller 200 includes a voltage source converter 124 configured to function as both a converter and an inverter. The voltage source converter 124 is substantially the same as the voltage source converter 124 of the power controller 100.

[0036]

[0036] The AC terminals of the voltage source converter 124 are electrically coupled to the modulation winding 202. The DC terminals of the voltage source converter 124 are electrically coupled to the energy storage means 130. The power controller 200 includes a bridge rectifier 134 configured to convert power from AC to DC. The AC terminals of the bridge rectifier 134 are electrically coupled in parallel to the load 118. The DC terminals of the bridge rectifier 134 are electrically coupled to the energy storage means 130.

[0037]

[0037] The power control device 200 includes a controller 240 that may be communicatively coupled to the voltage source converter 124. The controller 240 is configured to receive data related to parameters of an input electrical signal in the primary winding 110. The controller 240 is configured to compare the parameters of the input signal to parameters of a reference signal for the secondary winding 116. The reference signal includes, for example, an ideal waveform having desired parameters of an output signal free of noise or harmonics. The controller 240 is configured to determine a harmonic signal that, when applied to the modulation winding 202, causes the output electrical signal in the secondary winding 116 to approximate the reference signal, for example, by destructive interference. The controller 240 is configured to cause the harmonic signal to be applied to the modulation winding 202 using the voltage source converter 124. Thus, when the harmonic signal is applied, the output electrical signal in the secondary winding 116 is substantially identical to the reference signal.

[0038]

[0038] By applying the harmonic signal at a tap, such as tap 128, in the primary winding 110 rather than the modulation winding, the amount of copper required in the winding is reduced, reducing copper losses during operation of the power control device. Furthermore, a configuration having a tap in the winding requires less magnetic core surface area to induce the harmonic signal than a separate modulation winding.

[0039] An alternative configuration of the secondary side of the power controller is described with reference to FIGS.

[0040] 3, power controller 300 is substantially similar to power controller 100. In power controller 300, the AC terminals of bridge rectifier 134 are electrically coupled to a tap 302 in secondary winding 116.

[0041] 4, the power controller 400 is substantially similar to the power controller 100. The secondary leg 106 of the power controller 400 includes an output winding 402. In the power controller 400, the AC terminals of the bridge rectifier 134 are electrically coupled to the output winding 402.

[0042] Both power controller 300 and power controller 400 allow the voltage input to bridge rectifier 134 to be different from the voltage in secondary winding 116.

[0043]

[0043] An alternative configuration of the power controller includes a voltage source converter associated with each side of the magnetic core. The symmetrical arrangement of components on each side of the magnetic core allows for stabilization of the signal frequency through application of voltage droop control. This in turn allows for real-time demand to supply, i.e., temporary balancing of the load, which can be achieved even in the presence of negative power flows and highly nonlinear loads on both sides of the power controller.

[0044] 5, the power control device 500 includes a magnetic core 102 having a primary limb 104 and a secondary limb 106. The primary limb 104 includes a primary winding 110 that is electrically coupled to an AC power source 112. The secondary limb 106 includes a secondary winding 116 that is electrically coupled to a load 118.

[0045]

[0045] The power control device 500 comprises a first voltage source converter 502 and a second voltage source converter 504, each configured to function as both a converter and an inverter. The AC terminals of the first voltage source converter 502 are electrically coupled to the taps 128 in the primary winding 110. The DC terminals of the first voltage source converter 502 are electrically coupled to the energy storage means 130. The AC terminals of the second voltage source converter 502 are electrically coupled in parallel to the load 118. The DC terminals of the second voltage source converter 504 are electrically coupled to the energy storage means 130.

[0046] The power control device 500 includes a controller 510 that may be communicatively coupled to both the first voltage source converter 502 and the second voltage source converter 504. The controller 510 is configured to receive data related to parameters of an input electrical signal in the primary winding 110.

[0047] The controller 510 is configured to compare parameters of the input signal to parameters of a reference signal for the secondary winding 116. The reference signal includes, for example, an ideal waveform having desired parameters of an output signal free of noise or harmonics. The controller 510 is configured to determine a harmonic signal that, when applied to the primary winding 110, causes the output electrical signal in the secondary winding 116 to approximate the reference signal, for example, by destructive interference. The controller 510 is configured to apply the harmonic signal to the primary winding 110 using the first voltage source converter 502. Thus, when the harmonic signal is applied, the output electrical signal in the secondary winding 116 is substantially identical to the reference signal. The second voltage source converter 504 enables the power control device 500 to buffer additional energy.

[0048] 6, the power controller 600 is substantially the same as the power controller 500. The primary leg 104 of the power controller 600 includes a modulation winding 602. In the power controller 600, the AC terminals of the first voltage source converter 502 are electrically coupled to the modulation winding 602.

[0049] 7, the power control device 700 includes a magnetic core 102 having a primary limb 104 and a secondary limb 106. The primary limb 104 includes a primary winding 110 that is electrically coupled to an AC power source 112. The secondary limb 106 includes a secondary winding 116 that is electrically coupled to a load 118.

[0050]

[0050] The power control device 700 comprises a first voltage source converter 502 and a second voltage source converter 504, each configured to function as both a converter and an inverter. The AC terminals of the first voltage source converter 502 are electrically coupled to the tap 128 in the primary winding 110. The DC terminals of the first voltage source converter 502 are electrically coupled to the energy storage means 130. The AC terminals of the second voltage source converter 502 are electrically coupled in parallel to the load 118. The DC terminals of the second voltage source converter 504 are electrically coupled to the tap 702 in the secondary winding 116.

[0051]

[0051] The power control device 700 includes a controller 704 that may be communicatively coupled to both the first voltage source converter 502 and the second voltage source converter 504.

[0052]

[0052] The controller 704 is configured to receive data related to a parameter of a first signal in the primary winding 110. The controller 704 is configured to compare the parameter of the first signal with a parameter of a reference signal for the secondary winding 116. The reference signal includes, for example, an ideal waveform having the desired parameters of the second signal, free of noise or harmonics. The controller 704 is configured to determine a harmonic signal that, when applied to the primary winding 110, causes the second signal in the secondary winding 116 to approximate the reference signal, for example, by destructive interference. The controller 704 is configured to apply the harmonic signal to the primary winding 110 using the first voltage source converter 502. Thus, when the harmonic signal is applied, the second signal in the secondary winding 116 becomes substantially identical to the reference signal.

[0053]

[0053] The controller 704 may be configured to receive data related to parameters of the third signal in the secondary winding 116. The controller 704 is configured to compare the parameters of the third signal with parameters of a reference signal for the primary winding 110. The reference signal includes, for example, an ideal waveform having the desired parameters of the second signal without noise or harmonics. The controller 704 is configured to determine a harmonic signal that, when applied to the secondary winding 116, causes the fourth signal in the primary winding 110 to approximate the reference signal, for example, by destructive interference. The controller 704 is configured to apply the harmonic signal to the secondary winding 116 using the second voltage source converter 504. Thus, when the harmonic signal is applied, the fourth signal in the primary winding 110 becomes substantially identical to the reference signal.

[0054]

[0054] Thus, power controller 700 has a symmetrical arrangement such that either the primary side or the secondary side can receive an input signal.

[0055] 8, the power controller 800 is substantially the same as the power controller 700. The primary limb 104 of the power controller 800 includes a first modulation winding 802. The secondary limb 106 of the power controller 800 includes a second modulation winding 804. The AC terminals of the first voltage source converter 502 are electrically coupled to the first modulation winding 802. The AC terminals of the second voltage source converter 504 are electrically coupled to the second modulation winding 804.

[0056]

[0056] The AC power source 112 of any of the power controllers described above may be single phase. To support polyphase AC signals, the power control system may include multiple power controllers, i.e., one power controller for each phase. For example, in the case of a three-phase utility electric system, the power control system may include three power controllers as described above, but instead of three independent controllers, it has an integrated controller communicatively coupled to each of the voltage source converters. The integrated controller maintains the output signals of each phase independently. The voltage source converters of the power control system may be interconnected, for example, by a bus bar. This allows power to be transferred between the power controllers to balance the power across all three phases.

[0057]

[0057] Instead of one power controller per phase, a multi-phase magnetic core may be employed, for example an EI magnetic core or a magnetic core as described in GB Patent Application No. 2115649.2, which is incorporated herein by reference in its entirety. An exemplary three-phase magnetic core from GB Patent Application No. 2115649.2 will now be briefly described with reference to Figures 9A-9C.

[0058]

[0058] Referring to Figures 9A-9C, a magnetic core 900 includes three arcuate limbs 902 equally spaced about a central axis 904. Each limb 902 is substantially identical. The arcuate limbs 902 are 180 degree arcs. Each limb 902 has a first end and a second end. Each first end has a first edge located along the central axis 904. Each second end has a second edge located along the central axis. The first ends are joined to each other and the second ends are joined to each other. Each limb 902 may be wound with one or more of a primary winding, a secondary winding, and a modulation winding (not shown in Figures 9A-9C). Each limb 902 may include a plurality of magnetic steel strips curved and stacked together. The use of thin steel laminations reduces power losses caused by eddy currents induced when a sinusoidal voltage is applied to the windings. The width of the laminated magnetic steel strips may vary in an arrangement resulting in a limb 902 having a cross section approximating a circle. Alternatively, the width of the laminated magnetic steel strips in the limb 902 may be constant such that the limb has a rectangular cross section. The windings may be distributed or concentric. Preferably, distributed windings provide better leakage impedance and better thermal performance compared to concentric windings. Additionally, improved distribution of the magnetic field across the three-phase core is achieved in designs with a distributed winding topology. Distributed windings maintain lower levels of leakage impedance under identical operating conditions and maximize the voltage control range of the control system to avoid magnetic saturation of the ferromagnetic materials. For example, there may be a grid code requirement for an impedance percentage of 2% to 8%.

[0059] 10, the power control device 910 includes a magnetic core 901. The magnetic core 901 is a three-phase magnetic core, such as the magnetic core 900. The magnetic core 901 includes a first leg 902a, a second leg 902b, and a third leg 902c. The first leg 902a includes a first primary winding 912a and a first secondary winding 914a. The second leg 902b includes a second primary winding 912b and a second secondary winding 914b. The third leg 902c includes a third primary winding 912c and a third secondary winding 914c.

[0060] The first primary winding 912a is electrically coupled to a first AC power source 916a having a first phase. The second primary winding 912b is electrically coupled to a second AC power source 916b having a second phase. The third primary winding 912c is electrically coupled to a third AC power source 916c having a third phase. The AC power sources 916a, 916b, 916c can each carry one phase of a three-phase utility power source.

[0061] The first secondary winding 914a is electrically coupled to a first load 918a. The second secondary winding 914b is electrically coupled to a second load 918b. The third secondary winding 914c is electrically coupled to a third load 918c. The loads 918a, 918b, 918c may be one or more downstream loads that draw power from the power control device 910, such as a three-phase power grid.

[0062]

[0062] The power control device 910 includes six voltage source converters, each configured to function as both a converter and an inverter. Each voltage source converter includes a plurality of transistors and a plurality of capacitors. The first voltage source converter 920a includes an AC terminal and a DC terminal. The AC terminal of the first voltage source converter 920a is electrically coupled to a tap 912a in the first primary winding 922a. The DC terminal of the first voltage source converter 920a is electrically coupled to the first energy storage means 924a. The second voltage source converter 926a includes an AC terminal and a DC terminal. The AC terminal of the second voltage source converter 926a is electrically coupled to a tap 914a in the first secondary winding 928a. The DC terminal of the second voltage source converter 926a is electrically coupled to the first energy storage means 924a. The third voltage source converter 920b includes an AC terminal and a DC terminal. The AC terminal of the third voltage source converter 920b is electrically coupled to a tap 912b in the second primary winding 922b. The DC terminal of the third voltage source converter 920b is electrically coupled to the second energy storage means 924b. The fourth voltage source converter 926b includes an AC terminal and a DC terminal. The AC terminal of the fourth voltage source converter 926b is electrically coupled to a tap 914b in the second secondary winding 928b. The DC terminal of the fourth voltage source converter 926b is electrically coupled to the second energy storage means 924b. The fifth voltage source converter 920c includes an AC terminal and a DC terminal. The AC terminal of the fifth voltage source converter 920c is electrically coupled to a tap 912c in the third primary winding 922c. The DC terminal of the fifth voltage source converter 920c is electrically coupled to the third energy storage means 924c. The sixth voltage source converter 926c includes an AC terminal and a DC terminal. The AC terminal of the sixth voltage source converter 926c is electrically coupled to a tap 914c in the third secondary winding 928c. The DC terminal of the sixth voltage source converter 926c is electrically coupled to the third energy storage means 924c. The six voltage source converters may be interconnected, for example, by a bus bar.This allows power to be transferred between the voltage source converters to balance the power across all three phases. The three energy storage means 924a, 924b, 924c may be interconnected, for example, by a bus bar. The three energy storage means 924a, 924b, 924c may be the same energy storage means.

[0063]

[0063] Some or all of the voltage source converter may be connected to a modulation winding on a leg instead of being electrically coupled to a tap in the primary or secondary winding.

[0064] When an electrical signal from one of the AC power sources 916a, 916b, 916c is introduced into the primary windings of each of the legs of the AC power sources 916a, 916b, 916c, an electromagnetic field is induced in the magnetic core 901. The electromagnetic field in the magnetic core 901 induces electrical signals in the secondary windings of the other two legs.

[0065]

[0065] The power control device 910 includes a controller (not shown) that may be communicatively coupled to each of the six voltage source converters 920a, 920b, 920c, 926a, 926b, 926c. The controller is configured to receive data related to parameters of an input electrical signal in each of the primary windings 912a, 912b, 912c. For example, the parameters may include voltage, current, frequency, phase angle, and / or power factor. The controller may receive data from one or more voltage and / or current sensors.

[0066] The controller is configured to compare parameters of the input signal with parameters of a reference signal for each of the secondary windings 914a, 914b, 914c. The reference signals each include desired parameters of the output signal in each of the secondary windings, e.g., an ideal waveform free of noise or harmonics. The controller is configured to determine a set of harmonic signals including a harmonic signal for at least one of the primary windings 912a, 912b, 912c. When the set of harmonic signals is applied to at least one primary winding, the output electrical signal in the secondary windings 914a, 914b, 914c approximates the respective reference signal of the secondary windings 914a, 914b, 914c, e.g., by destructive interference. The controller is configured to cause the set of harmonic signals to be applied to the primary windings 912a, 912b, 912c using the voltage source converters 920a, 920b, 920c. Thus, when a set of harmonic signals is applied, the output electrical signals in the secondary windings 914a, 914b, 914c will be substantially identical to the reference signals of each of the secondary windings 914a, 914b, 914c.

[0067]

[0067] The third harmonic may be cancelled by balancing the load among the three phases. The controller may also be configured to provide additional voltage control for the unbalanced load by eliminating other harmonics and presenting the unbalanced load to the power grid as balanced. This is achieved by controlling the amplitude and phase of the harmonic signals in the set of harmonic signals independently for each limb. This provides six degrees of freedom to the power controller to achieve various control objectives. One possible control objective is to vary the secondary voltages on each limb in equal proportions, but leave the ratio of the primary currents in the corresponding limbs unchanged, compared to the passive, i.e., unmodulated, operation of the power controller. Another possible control objective is to vary the output voltages of each limb, but at the same time redistribute the primary currents. One possible option for redistribution is to make the magnitudes of the three primary currents equal and to keep the phases of the three primary currents 120 degrees and 240 degrees apart, thus achieving substantially equal load sharing from the primary perspective.

[0068]

[0068] Using a single magnetic core to modulate a multi-phase AC signal, rather than using a single-phase magnetic core for each phase to modulate the same multi-phase AC signal, allows modulation of inter-phase harmonics and noise in addition to intra-phase harmonics and noise. The use of a multi-phase magnetic core also reduces the amount of physical iron required compared to multiple single-phase cores. Additionally, load and no-load losses may be reduced with a multi-phase magnetic core compared to multiple single-phase cores.

[0069]

[0069] Instead of a pair of voltage source converters for each phase, a pair of three-phase voltage source converters may be used. Referring to Fig. 11, power controller 950 is substantially similar to power controller 910 and includes a magnetic core 901. Magnetic core 901 is a three-phase magnetic core, such as magnetic core 900. Magnetic core 901 includes a first leg 902a, a second leg 902b, and a third leg 902c. First leg 902a includes a first primary winding 912a and a first secondary winding 914a. Second leg 902b includes a second primary winding 912b and a second secondary winding 914b. Third leg 902c includes a third primary winding 912c and a third secondary winding 914c.

[0070] The first secondary winding 914a is electrically coupled to a first load 918a. The second secondary winding 914b is electrically coupled to a second load 918b. The third secondary winding 914c is electrically coupled to a third load 918c. The loads 918a, 918b, 918c may be one or more downstream loads that draw power from the power control device 950, such as a three-phase power grid.

[0071]

[0071] The power control device 950 includes a first voltage source converter 952 and a second voltage source converter 954, each configured to function as both a converter and an inverter. Each voltage source converter is a three-phase voltage source converter and includes a plurality of transistors and a plurality of capacitors. Each voltage source converter includes an AC terminal and a DC terminal. The DC terminals of the first and second voltage source converters 952, 954 are each electrically coupled to an energy storage means 956. The AC terminal of the first voltage source converter 952 is electrically coupled to each of a tap 922a in the first primary winding 912a, a tap 922b in the second primary winding 912b, and a tap 922c in the third primary winding 912c. The AC terminals of the second voltage source converter 954 are electrically coupled to each of the taps 928a in the first secondary winding 914a, 928b in the second secondary winding 914b, and 928c in the third secondary winding 914c. Some or all of the voltage source converters may be connected to modulation windings on the limbs instead of being electrically coupled to taps in the primary or second windings.

[0072] When an electrical signal from one of the AC power sources 916a, 916b, 916c is introduced into the primary windings of each of the legs of the AC power sources 916a, 916b, 916c, an electromagnetic field is induced in the magnetic core 901. The electromagnetic field in the magnetic core 901 induces electrical signals in the secondary windings of the other two legs.

[0073]

[0073] The power control device 950 includes a controller (not shown) that may be communicatively coupled to each of the first and second voltage source converters 952, 954. The controller is configured to receive data related to parameters of an input electrical signal in each of the primary windings 912a, 912b, 912c. For example, the parameters may include voltage, current, frequency, phase angle, and / or power factor. The controller may receive data from one or more voltage and / or current sensors.

[0074] The controller is configured to compare parameters of the input signal with parameters of a reference signal for each of the secondary windings 914a, 914b, 914c. The reference signals each include desired parameters of the output signal in each of the secondary windings, e.g., an ideal waveform free of noise or harmonics. The controller is configured to determine a set of harmonic signals including a harmonic signal for at least one of the primary windings 912a, 912b, 912c. When the set of harmonic signals is applied to at least one primary winding, the output electrical signal in the secondary windings 914a, 914b, 914c approximates the respective reference signal of the secondary windings 914a, 914b, 914c, e.g., by destructive interference. The controller is configured to cause the set of harmonic signals to be applied to the primary windings 912a, 912b, 912c using a first voltage source converter 952. Thus, when a set of harmonic signals is applied, the output electrical signals in the secondary windings 914a, 914b, 914c will be substantially identical to the reference signals of each of the secondary windings 914a, 914b, 914c.

[0075]

[0075] Referring to Figure 12, a method 1100 for modulating a second signal in a secondary winding of a power controller, such as any of the power controllers described above, is described. The power controller has a magnetic core with a first limb and a second limb, with a primary winding disposed about the first limb and a secondary winding disposed about the second limb. The method 1100 is performed by a controller and includes, at step 1102, receiving data related to a parameter of the first signal in the primary winding. For example, the parameters may include voltage, current, frequency, phase angle, and / or power factor. The controller may receive data from one or more voltage and / or current sensors. The data related to the parameter may be received from one or more voltage and / or current sensors associated with the primary winding and / or secondary winding.

[0076]

[0076] In step 1106, the controller compares parameters of the first signal with parameters of reference signals for the secondary windings. The reference signals each include desired parameters of the output signal in each of the secondary windings, e.g., an ideal waveform free of noise or harmonics.

[0077]

[0077] In step 1110, the controller determines a harmonic signal that when applied to the first limb causes the output electrical signal in the secondary winding to approximate the reference signal, for example by destructive interference. In step 1114, the controller causes the harmonic signal to be applied to the first limb using a voltage source converter. In a power control device where the primary winding includes a tap, the voltage source converter is connected to the tap, and the voltage source converter is configured to apply the harmonic signal to the first limb using the tap. In a power control device where the first limb includes a modulation winding, the voltage source converter is connected to the modulation winding, and the voltage source converter is configured to apply the harmonic signal to the first limb using the modulation winding. When the harmonic signal is applied, the output electrical signal in the secondary winding is substantially identical to the reference signal.

[0078]

[0078] In this disclosure, unless the context indicates otherwise, the term "signal" is used for ease of reference and should be interpreted broadly to refer to a form of electrical energy characterized by voltage, current, and at least one fundamental frequency (which may be zero in the case of DC voltage), and does not necessarily require that any form of information be represented or conveyed by the signal.

[0079]

[0079] Although the present invention has been described in relation to several embodiments, it is not intended to be limited to the specific form described herein. Rather, the scope of the present invention is limited only by the appended claims. Moreover, although a feature may appear to be described in relation to a specific embodiment, one skilled in the art will recognize that various features of the described embodiments may be combined in accordance with the present invention. In the claims, the term "comprises" or "includes" does not exclude the presence of other elements.

[0080]

[0080] Any of the controllers described above represent one or more general-purpose processors, such as a microprocessor or a central processing unit. More specifically, the controller may be a complex instruction set computing (CISC) microprocessor, a reduced instruction set computing (RISC) microprocessor, a very long instruction word (VLIW) microprocessor, a processor implementing other instruction sets, or a processor implementing a combination of instruction sets. The controller may also be one or more special-purpose processing devices, such as an application specific integrated circuit (ASIC), a field programmable gate array (FPGA), a digital signal processor (DSP), or a network processor. The controller is configured to execute processing logic for performing the operations and steps discussed herein.

[0081]

[0081] The controller may be communicatively coupled to a data storage device. The data storage device may include one or more machine-readable storage media (or more specifically, one or more non-transitory computer-readable storage media) having stored thereon one or more sets of instructions embodying any one or more of the methodologies or functions described herein. The instructions may also reside completely or at least partially within the controller during execution of the instructions.

[0082]

[0082] The various methods described above may be implemented by a computer program. The computer program may include computer code configured to instruct a computer to perform one or more functions of the various methods described above. The computer program and / or code for performing such methods may be provided to an apparatus such as a computer on one or more computer readable media, or more generally on a computer program product. The computer readable medium may be transitory or non-transitory. The one or more computer readable media may be, for example, electronic, magnetic, optical, electromagnetic, infrared, or semiconductor systems, or a propagation medium for data transmission, for example, for downloading code via the Internet. Alternatively, the one or more computer readable media may take the form of one or more physical computer readable media, such as semiconductor or solid state memory, magnetic tape, removable computer diskettes, random access memory (RAM), read only memory (ROM), rigid magnetic disks, and optical disks.

Claims

1. A power control device (950), A magnetic core (901) comprising a first limb (902a), a second limb (902b), and a third limb (902c), the first limb (902a), the second limb (902b), and the third limb (902c) are each arc-shaped limbs; each limb being arranged about a central axis; Each limb (902a, 902b, 902c) has a first end and a second end; the first ends of the limbs are connected to one another at a first location along the central axis; the second ends of the limbs are interconnected at a second location along the central axis. A magnetic core (901); a primary winding (912a) disposed about the first leg (902a), the primary winding (912a) electrically coupled to a first AC power source (916a) having a first phase, the first AC power source (916a) inducing a first signal in the primary winding; a second secondary winding (914b) disposed around the second leg (902b), the second secondary winding (914b) being electrically coupled to a second load (918b); a third secondary winding (914c) disposed about the third limb (902c), the third secondary winding (914c) being electrically coupled to a third load (918c); a first voltage source converter (952) having an AC connection and a DC connection, the AC connection of the first voltage source converter (952) is electrically coupled to the primary winding (912a); or a first voltage source converter (952), the power control device (950) comprising a modulation winding disposed about the first leg (902 a), the AC connection of the first voltage source converter (952) being electrically coupled to the modulation winding disposed about the first leg (902 a); a second voltage source converter (954) having an AC connection and a DC connection, the AC connection of the second voltage source converter (954) is electrically coupled to each of the second secondary winding (914b) and the third secondary winding (914c); or a second voltage source converter (954), wherein the power control device (950) includes a respective modulation winding disposed around each of the second and third legs (902b, 902c), the AC connection of the second voltage source converter (954) being electrically coupled to each of the modulation windings disposed around each of the second and third legs (902b, 902c); a controller communicatively coupled to each of the first voltage source converter (952) and the second voltage source converter (954), receiving data relating to a parameter of the first signal in the primary winding (912a); comparing the parameter of the first signal with a parameter of a respective reference signal for each of the second secondary winding (914b) and the third secondary winding (914c); determining a harmonic signal that, when applied to the first leg (902a), causes a respective second signal in each of the second secondary winding (914b) and the third secondary winding (914c) to approximate the respective reference signal; and applying the harmonic signal to the first leg (902a) using the first voltage source converter (952); a controller configured to: A power control device (950) comprising:

2. the AC connection of the first voltage source converter (952) is electrically coupled to the primary winding (912a); 2. The power control device (950) of claim 1, wherein the controller is configured to cause the first voltage source converter (952) to apply the harmonic signal to the first leg (902a) by causing the first voltage source converter (952) to apply the harmonic signal to the primary winding (912a).

3. The power control device (950) of claim 2, wherein the AC connection of the voltage source converter is electrically coupled to a tap along the primary winding.

4. The AC connection of the voltage source converter is electrically coupled to the modulation winding; 2. The power control device (950) of claim 1, wherein the controller is configured to cause the first voltage source converter (952) to apply the harmonic signal to the first leg (902 a) by causing the first voltage source converter (952) to apply the harmonic signal to the modulation winding.

5. 5. The power control device (950) of claim 1, wherein the AC connection of the second voltage source converter (954) is electrically coupled to a tap along the second secondary winding (914b).

6. 5. The power control device of claim 1, wherein the AC connection of the second voltage source converter is electrically coupled in parallel to a load on the second secondary winding.

7. an energy storage means (956) coupled to the DC connection of the first voltage source converter (952); The power control device (950) of any one of claims 1 to 4, wherein the energy storage means comprises one or more of a capacitor, a battery, a flywheel, a thermal energy storage device, an electrolyzer, a heat pump, and an air compressor.

8. The power control device according to any one of claims 1 to 4, wherein the magnetic core has a toroidal shape.

9. the primary winding (912a) is a first primary winding; the power control device (950) comprising a second primary winding (912b) disposed around the second leg (902b) and a third primary winding (912c) disposed around the third leg (902c); 5. The power control device (950) of claim 1, wherein each of the first primary winding (912a), the second primary winding (912b), and the third primary winding (912c) is configured to carry a different phase of a three-phase AC signal.

10. 5. The power control device (950) of claim 1, wherein the harmonic signal causes the respective second signals in each of the second secondary winding (914b) and the third secondary winding (914c) to approximate the respective reference signals by compensating for harmonics in the first signals, such that the harmonics are eliminated or reduced in the respective second signals.

11. 1. A method for modulating a respective second signal in each of a second secondary winding (914b) and a third secondary winding (914c) of a power control device (950) having a magnetic core (901) with a first leg (902a), a second leg (902b), and a third leg (902c), comprising: the first limb (902a), the second limb (902b), and the third limb (902c) are each arc-shaped limbs; Each of the limbs (902a, 902b, 902c) is arranged around a central axis; Each limb (902a, 902b, 902c) has a first end and a second end; the first ends of the limbs are connected to one another at a first location along the central axis; the second ends of the limbs are connected to one another at a second location along the central axis; a primary winding (912a) disposed about the first limb (902a), the primary winding electrically coupled to a first AC power source (916a) having a first phase, the first AC power source (916a) inducing a first signal in the primary winding; the second secondary winding (914b) is disposed around the second limb (902b); the third secondary winding (914c) is disposed around the third limb (902c); the second secondary winding (914b) is electrically coupled to a second load (918b); the third secondary winding (914c) is electrically coupled to a third load (918c); the power control device (950) further comprises a first voltage source converter (952) having an AC connection and a DC connection, and a second voltage source converter (954) having an AC connection and a DC connection; the AC connection of the first voltage source converter (952) is electrically coupled to the primary winding (912a); or the power control device (950) comprises a modulation winding disposed about the first leg (902 a), the AC connection of the first voltage source converter (952) being electrically coupled to the modulation winding disposed about the first leg (902 a); and the AC connection of the second voltage source converter (954) is electrically coupled to each of the second secondary winding (914b) and the third secondary winding (914c); or the power control device (950) includes a respective modulation winding disposed around each of the second and third legs (902b, 902c), the AC connection of the second voltage source converter (954) being electrically coupled to each of the modulation windings disposed around each of the second and third legs (902b, 902c); The method comprises: receiving data relating to a parameter of a first signal in the primary winding; comparing the parameter of the first signal with a parameter of a respective reference signal for each of the second secondary winding and the third secondary winding; determining a harmonic signal that, when applied to the first limb, causes the respective second signal in each of the second secondary winding and the third secondary winding to approximate the respective reference signal; applying the harmonic signal to the first limb using the first voltage source converter; A method comprising:

12. applying the harmonic signal to the first limb using the first voltage source converter; applying the harmonic signal to the primary winding using the first voltage source converter. The method of claim 11 , comprising:

13. The step of applying the harmonic signal to the primary winding using the first voltage source converter, applying the harmonic signal to a tap in the primary winding using the first voltage source converter.

13. The method of claim 12, comprising:

14. applying the harmonic signal to the first limb using the first voltage source converter; applying the harmonic signal using the first voltage source converter to the modulation winding disposed about the first limb. The method of claim 11 , comprising:

15. 13. The method of claim 11 or 12, wherein the harmonic signal causes the respective second signal in each of the second secondary winding and the third secondary winding to approximate the respective reference signal by compensating for harmonics in the first signal, such that the harmonics are eliminated or reduced in the respective second signal.

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