Converter and method of controlling a converter

Abstract

The invention relates to a converter (1, 7) with a converter control device (14), wherein the converter control device comprises a current controller (16) configured to receive at its input a difference between a current setpoint and a measured converter current and to provide at its output a current controller output voltage, and a damping module (17) configured to receive at its input the measured converter current and to provide at its output a damping voltage, wherein the sum of the damping voltage and the converter controller output voltage is provided to a converter modulator. The invention is characterized in that the converter control device further comprises a virtual admittance module (19) configured to receive at its input a difference between a sum of a voltage setpoint and a compensation voltage and the current controller output voltage and to provide at its output the current setpoint, and a compensation module (20) configured to receive at its input the current setpoint and to provide at its output the compensation voltage, wherein the compensation module is configured to counteract the damping effect of the damping module. The invention further relates to a control method for controlling the converter.

Description

Technical Field

[0001] The present invention relates to a converter having a converter control device, wherein the converter control device includes a current controller and a damping module. The current controller is configured to receive the difference between a current setpoint and a measured converter current at its input and to provide a current controller output voltage at its output. The damping module is configured to receive the measured converter current at its input and to provide a damping voltage at its output. The sum of the damping voltage and the converter controller output voltage is provided to a converter modulator. Background Technology

[0002] Such a current-controlled converter is known in EP 4 057 500 A1. The known converter control device dampens the converter voltage by applying a virtual impedance that adds a correction voltage to the current controller output voltage. Therefore, the damping module can be used as a modifier of the converter's input impedance, i.e., the impedance measured on the AC side of the converter.

[0003] Typically, converters operating in so-called grid-following mode use a grid-following controller to control the AC-side current and employ phase-locked loop (PLL) control to follow the frequency and phase angle of the grid voltage (the voltage across the AC network) (thus synchronizing with the grid). Currently, most existing converters in high-voltage applications operate in grid-following mode.

[0004] In recent years, the high penetration rate of power electronic devices (such as HVDC and STATCOM) and renewable energy installations under relatively weak grid conditions has significantly increased the necessity of implementing grid-connected converters (i.e., converters operating in grid-connected mode). In grid-connected mode, the converter actively controls its frequency and voltage output.

[0005] Typically, known concepts for generating synchronous voltage sources exhibiting desired grid-connected characteristics are based on two key components: a software implementation of the oscillation equations for modeling the frequency behavior and inertia of a physical synchronizer with a rotating spatial phasor; and a voltage controller for the voltage amplitude of that phasor. However, applying these theoretical control concepts to practical AC / DC converter hardware and the existing functional requirements of HVDC converter stations presents numerous challenges. For example, current constraints in the converter hardware require a fast current controller with current source-like behavior and high input impedance, while the voltage source behavior required by grid-connected converters demands very low input impedance. Furthermore, harmonic damping requires a high real part of the internal impedance, resulting in a low X / R ratio, while voltage and angular stability criteria, and the inherent response to grid voltage variations (angle and amplitude), demand a very high X / R ratio. Summary of the Invention

[0006] Therefore, the object of the present invention is to provide a converter that can achieve a sufficiently high X / R ratio from the perspective of network requirements, while keeping the damping of the current controller at the level required for operation.

[0007] This objective is achieved by the converter according to claim 1.

[0008] Therefore, the converter control device further includes a virtual admittance module and a compensation module. The virtual admittance module is configured to receive the difference between the sum of the voltage setpoint and the compensation voltage and the output voltage of the current controller at its input, and to provide the current setpoint at its output. The compensation module is configured to receive the current setpoint at its input and to provide the compensation voltage at its output. The compensation module is configured to counteract the damping effect of the damping module, appropriately for a predefined frequency range of the current setpoint (preferably for the full frequency range of the current setpoint). According to the invention, the compensation module is configured to model the behavior of the damping module to approximately compensate for its effect. Within the predefined range of the current setpoint, the output voltage of the compensation module (compensation voltage) approximates the output voltage of the damping module (damping voltage). At least except under transient conditions, i.e., in steady-state operation, the compensation voltage is ideally equal to the damping voltage (provided that an ideal model of the current controller is implemented in the compensation module). If the permissible current setting is limited, for example to protect the converter hardware, no compensation effect will occur for currents exceeding this value (the current setting limit), because the compensation module receives the current setting, while the effect of the damping module depends directly on the measured current.

[0009] Therefore, the converter control unit includes a dedicated grid control system with an underlying fast current controller that acts as a current limiter. The grid system consists of dedicated voltage, angle, and frequency controllers, as well as a voltage controller that simulates the frequency behavior and inertia of a physical synchronizer with a rotating spatial phasor. The voltage controller generates the voltage amplitude for this phasor. The interface between the grid controller and the current controller is implemented through a virtual admittance module, which can be interpreted as an RL grid model with defined short-circuit levels and an X / R ratio.

[0010] One advantage of this invention is that the high damping of the current controller does not limit the grid response by reducing the effective X / R ratio of the entire system. The current controller is implemented to provide sufficient damping with fast current limiting capability (which is necessary for power electronics). The damped current controller behavior can be compensated (statically and dynamically) in the upper admittance of grid control to achieve the desired high X / R ratio.

[0011] The current controller adjusts the converter current to the desired current setpoint in a very short time by controlling the voltage at the converter terminals. Therefore, the virtual voltage drop across the current controller damping can be compensated by positive feedback to the input of the virtual admittance module.

[0012] By utilizing the described damping reduction system implementation, the gridded system maintains its ability to selectively control voltage components. Therefore, separate positive and negative phase sequence current control setpoints can be generated. This makes the gridded behavior closer to that of a real positive phase sequence voltage source, which is typically the behavior desired by customers and is also desirable for other control functions such as active harmonic damping / filtering or voltage modulation. The proposed architecture breaks the dependency between current controller damping and the desired X / R ratio and resolves the trade-offs that control designers must make in systems with very low effective X / R ratios. The converter operating in gridded mode can operate in both directions (inverter and rectifier) ​​in a manner closer to ideal voltage behavior.

[0013] Preferably, the compensation module includes a converter control model and a damping model. The converter control model is used to determine the converter current based on the current setpoint, and the damping model is used to model the damping module. The compensation model may include two mapping / function components for subsequent application. The first function component models the behavior of the converter and the converter control device to obtain the actual converter current as a function of the current setpoint. The model for the converter control device can be derived from known model equations that model the converter behavior (including the current controller). The second function component may be a transfer function, preferably a copy of the transfer function of the damping module.

[0014] The converter control unit can be configured to limit the current setpoint so that it does not exceed a predefined current setpoint limit, thus preventing the current setpoint from exceeding the converter's current capacity. Since the compensation module's input is the current setpoint, the compensation voltage will not exceed the maximum voltage output corresponding to the upper limit of the current setpoint. In contrast, since the damping unit's input is the actual converter current, the damping voltage can exceed this maximum voltage output. This is especially true for current values ​​that could damage the converter. Therefore, such currents can be effectively damped.

[0015] According to one embodiment of the invention, compensation is performed separately for the positive and negative phase sequence voltages and currents. Therefore, the virtual admittance module is a positive phase sequence virtual admittance module, configured to receive at its input the difference between the sum of the positive phase sequence voltage setpoint and the positive phase sequence compensation voltage and the output voltage of the positive phase sequence current controller, and to provide the positive phase sequence current setpoint at its output. The compensation module is a positive phase sequence compensation module, configured to receive the positive phase sequence current setpoint at its input and to provide the positive phase sequence compensation voltage at its output. By separating the control of the positive and negative phase sequences, phase sequence selective control can be achieved, wherein the positive and negative phase sequence current components have different controller behaviors.

[0016] Preferably, the converter control device further includes a negative phase sequence virtual admittance module and a negative phase sequence compensation module. The negative phase sequence virtual admittance module is configured to receive the difference between the sum of the negative phase sequence voltage setpoint and the negative phase sequence compensation voltage and the output voltage of the negative phase sequence current controller at its input terminal, and to provide the negative phase sequence current setpoint at its output terminal. The negative phase sequence compensation module is configured to receive the negative phase sequence current setpoint at its input terminal and to provide the negative phase sequence compensation voltage at its output terminal, wherein the current setpoint is the sum of the positive phase sequence current setpoint and the negative phase sequence current setpoint. This allows the current reference / measured value used for grid control to be divided into different components (positive phase sequence PPS / negative phase sequence NPS), which improves compatibility with functions affecting various components of the current, such as current limiting, current component priority ranking (active and reactive current components), and support functions such as active damping and voltage modulation.

[0017] According to one embodiment, the current controller is a positive phase sequence current controller, which receives the difference between the current setpoint and the measured converter current at its input terminal and provides the positive phase sequence current controller output voltage at its output terminal. The converter control device further includes a negative phase sequence current controller, which receives the difference between the current setpoint and the measured converter current at its input terminal and provides the negative phase sequence current controller output voltage at its output terminal.

[0018] According to one aspect of the invention described above, the positive and negative phase sequence components can be controlled independently, and the admittances of PPS and NPS can be set separately. This allows for the separation of the inherent short-circuit capabilities of PPS and NPS, thereby enabling differentiated responses during asymmetrical grid conditions. The current controller can be tuned to the resonant frequencies of the PPS and NPS components. In this way, the PPS and NPS converter voltages are extracted and fed back to the input of the virtual impedance individually for each component. The positive phase sequence component is compared with a voltage generated by a grid voltage source model, while the negative phase sequence is compared with a zero setpoint, or equivalently with a grid voltage source model for NPS. Thus, current setpoints for PPS and NPS are generated via virtual admittances, and these current setpoints can be limited individually. In a subsequent step, the two setpoints are summed and used as the input signal for the current controller. One advantage of separating the PPS and NPS is that the positive phase sequence current can be limited separately for the d and q components in the dq domain without cross-coupling to the NPS component, and without generating unwanted harmonics, which would occur, for example, when the PPS and NPS components are transformed as a combined signal to a 50 Hz rotating coordinate system and limited therein. Another advantage is that different admittances can be determined for the positive and negative phase sequences, thus allowing for more accurate specification of the NPS component injection gain.

[0019] The separation of PPS and NPS mentioned above can also take into account the zero-sequence components of each signal.

[0020] Preferably, the damping module includes a transfer function. The transfer function can be implemented as a linear amplification function. The damping module may also include an integrator.

[0021] The virtual admittance module can include a combination of linear and nonlinear transfer functions. The transfer functions of the damping module and / or the virtual admittance module can be implemented to operate in the Laplace domain.

[0022] According to one embodiment, the converter includes a turn-off controllable semiconductor switch. The converter includes an AC side for connection to an AC network and a DC side for connection to a DC link or energy storage device. The concepts described herein can be used in SVC frequency stabilizer devices, such as those based on a B6 converter, with a supercapacitor connected to the DC terminals. The B6 converter configuration is characterized by three converter phase branches, each extending between the DC terminals. Each phase branch includes two converter valves (thus a total of six converter valves), with the AC terminals arranged between the corresponding converter valves of each converter phase. The energy storage device connected to the DC side of the converter enables operation for several seconds within the active power range. When the voltage limit of the DC-side supercapacitor is exceeded, the storage device will be charged or discharged accordingly, thereby allowing islanded operation of the SVC frequency stabilizer. The voltage setpoint can be calculated by an automatic voltage regulator (AVR) that controls the voltage at the connection point to a given reference value. The response speed of the controller determines the stability of the converter during islanded conditions. Under normal conditions, the active power of the frequency stabilizer is zero. During frequency disturbances, active power is injected / absorbed to offset the frequency change.

[0023] The converter is preferably a modular multilevel converter (MMC). A modular multilevel converter (MMC) includes a series of switching modules in each converter valve (sometimes also referred to as a converter arm). Each switching module includes a turn-off semiconductor switch, such as an IGBT, and an energy storage device, such as a capacitor. Each switching module can be individually controlled to provide a specific module voltage at its terminals (e.g., capacitor voltage or zero voltage in the case of a half-bridge module, or capacitor voltage, negative capacitor voltage, or zero voltage in the case of a full-bridge module).

[0024] The present invention also relates to a method for operating or controlling a converter according to the present invention.

[0025] The object of this invention is to provide a method that can achieve a sufficiently high X / R ratio from the perspective of network requirements, while keeping the damping of the current controller at the level required for operation.

[0026] This objective is achieved by the converter according to claim 10.

[0027] Therefore, the method includes the following steps: receiving the difference between a current setpoint and a measured converter current at the input of a current controller, and providing a current controller output voltage at its output; receiving the measured converter current at the input of a damping module, and providing a damping voltage at its output, wherein the sum of the damping voltage and the current controller output voltage is provided to a converter modulator; receiving the difference between the sum of a voltage setpoint and a compensation voltage and the current controller output voltage at the input of a virtual admittance module, and providing the current setpoint at its output; and receiving the current setpoint at the input of a compensation module, and providing the compensation voltage at its output, wherein the compensation module counteracts the damping effect of the damping module within a predefined range of the current setpoint. Attached Figure Description

[0028] The following is combined Figures 1 to 5 The exemplary embodiments shown illustrate the present invention.

[0029] Figure 1 A schematic diagram of a converter according to an embodiment of the present invention is shown; Figure 2 It shows Figure 1 Another schematic diagram of the converter; Figure 3 A schematic diagram of one embodiment of a converter control device for a converter according to the present invention is shown; Figure 4 A schematic diagram of another embodiment of a converter control device for a converter according to the present invention is shown; Figure 5 A schematic diagram of yet another embodiment of a converter control device for a converter according to the present invention is shown. Detailed Implementation

[0030] Figure 1 A converter 1 with an AC side 2 and a DC side 3 is shown. Converter 1 is a voltage source converter, specifically a modular multilevel converter (MMC). The AC side 2 of converter 1 is connected to the AC power grid 4 at connection point 2a. The DC side 3 of converter 1 is connected to the energy storage device 5 via a DC link 6. Converter 1 is designed to stabilize the AC power grid 4 by exchanging active and reactive power with it.

[0031] Figure 2The MMC 7 shown includes three phase branches 8a-c and six converter valves (also referred to as arms) 9a-f. Each converter arm 9a-f extends between one of the DC poles or terminals 10a, 10b constituting the DC side of the converter 7 and one of the AC terminals 11a-c constituting the AC side of the converter 7. Each converter valve 9a-f includes an arm inductor L and a plurality of switch modules 12 connected in series. The number of switch modules 12 in each converter arm 9a-f is typically arbitrary (not limited to two per valve) and can be adapted to a given application. Figure 2 In the example shown, all switching modules 12 are so-called full-bridge switching modules. Proper control of the semiconductor switches in a given switching module 12 will generate a positive, negative, or zero voltage across its terminals. The converter 7 includes a converter control unit 13 for controlling the operation of the converter 7.

[0032] MMC 7 is suitable for grid stability applications (according to...) Figure 1 (Configuration). However, the present invention is also applicable to high-voltage direct current (HVDC) transmission, such as using MMC 7, where its DC side is connected to a DC transmission line. Especially in HVDC applications, each converter valve may include a full-bridge switching module, a half-bridge switching module, other switching module topologies, or any combination thereof.

[0033] Figure 3 It shows the applicability Figure 1 and / or Figure 2 The converter control system 14 of the converter shown is included. The converter control system 14 includes a network control unit 15. The network control unit 15 provides a voltage setpoint Vset at its output. The network control unit 15 controls the converter to behave in terms of impedance (viewed from the point of common coupling, e.g.) Figure 1 The ideal voltage source following point 2a). The voltage setpoint is provided as a phasor with angle and amplitude.

[0034] The converter control device 14 also includes a current controller 16. At its input, the converter controller 16 receives a current setpoint Iconvset and the measured actual converter current Iconvmeas, the difference Iconvset - Iconvmeas. The current can be, for example, the current flowing through the converter's AC terminals. The current controller can be, for example, a second-order generalized integrator, a dq controller, a resonant controller, or a similar device. The current controller 16 provides a current controller output voltage Vact at its output.

[0035] The converter control unit 14 also includes a damping module 17. The damping module 17 receives the measured converter current Iconvmeas at its input and provides a damped voltage Vdamp at its output via a transfer function (which may also be frequency selective). The current controller output voltage Vact is corrected by the damped voltage Vdamp (e.g., by subtracting Vact-Vdamp) and provided to the converter modulator 18, which controls the converter switching according to a modulation algorithm. Therefore, the voltage to be generated by the converter is reduced based on the actual converter current. This prevents the converter from generating a voltage that may exceed its current capability and, consequently, a current that may exceed its current capability.

[0036] The output of the network control device 15 is connected to the current controller 16 via a virtual admittance module 19 (e.g., implemented as a linear, nonlinear, or combined linear / nonlinear transfer function in the corresponding control module). This allows for very fast and efficient current limiting in the converter. The virtual admittance module 19 provides a current setpoint Iconvset at its output. The current setpoint Iconvset is provided to the current controller 16 and the compensation module 20. The compensation module 20 includes a model of the converter control device. Using this model, the current setpoint Iconvset is converted into an actual converter current response that approximates the actual converter response. This model response is further transformed by a transfer function to provide a compensation voltage Vcomp at the output of the compensation module 20. During steady-state operation of the converter, the compensation voltage Vcomp is approximately equal to the damping voltage Vdamp. To compensate for the damping effect of the damping module 17, the compensation voltage Vcomp, along with the voltage setpoint Vset and the current controller output voltage Vact, is provided to the virtual admittance module 19. The current setpoint Iconvset is limited by the limiting function 21, that is, if the current setpoint Iconvset exceeds the current setpoint limit, then the current setpoint Iconvset is set to the current setpoint limit. This specifically means that for all measured currents above the current setpoint limit, the compensation module 20 does not compensate for the damping effect of the damping module 17.

[0037] Figure 4 Another variation of the converter control device 30 is shown. The basic structure of the converter control device 30 is similar to... Figure 3 The control device shown. However, according to Figure 4 In one embodiment, the converter control is performed separately for the positive and negative phase sequence components of the voltage and / or current. A separate corresponding zero-sequence component can also be implemented additionally in the converter control device.

[0038] The converter control unit 30 includes a grid control unit 31 for providing positive phase sequence voltage reference values ​​Vset,pps and Vset,nps. The grid control 31 is based on the energy reference values ​​and measured power and voltage values ​​WOphmact, Wwphm, Vref, Qref, Vact, and Qact. The grid control unit 31 includes a transfer function 32 for controlling energy, a transfer function 33 for controlling reactive power, and an extended electromechanical and electromagnetic model 34 of the converter.

[0039] The converter control device 30 also includes a positive phase sequence virtual admittance module 35 and a negative phase sequence virtual admittance module 36. The positive phase sequence virtual admittance module includes a transfer function, and the negative phase sequence virtual admittance module is used to couple the network control device and the current controller, for example... Figure 5 As shown, the sum of the positive phase sequence current setpoint Iconvset,pps and the negative phase sequence current setpoint Iconvset,nps is provided to the current controller for further processing.

[0040] To compensate for the effect of the damping module, such as Figure 5 As shown, the converter control device 30 also includes a positive phase sequence compensation module 37 and a negative phase sequence compensation module 38. The implementation and effects of the positive phase sequence compensation module 37 and the negative phase sequence compensation module 38 correspond to the reference... Figure 4 The effect of the compensation module 20 is described.

[0041] Figure 5 A converter control device 40 with a current control system is shown, which can be applied, for example, to... Figure 4 The converter control device 40 includes a positive phase sequence current controller 41 and a negative phase sequence current controller 42. The positive phase sequence current controller receives the difference between the current setpoint Iconvset and the measured converter current Iconvmeas at its input terminal and provides a positive phase sequence current controller output voltage Vact,pps at its output terminal. The negative phase sequence current controller receives the difference between the current setpoint Iconvset and the measured converter current Iconvmeas at its input terminal and provides a negative phase sequence current controller output voltage Vact,nps at its output terminal. The sum of the output voltages Vact,pps and Vact,nps is corrected by the damping voltage Vdamp provided by the damping module 43 and transmitted to the converter modulator. The implementation and effect of the damping module 43 are described above regarding... Figure 3 The damping module 17 is described.

[0042] A converter operating in network mode is expected to behave as a slowly varying voltage source behind an impedance, similar to a physical synchronous machine. However, semiconductor-based power electronics do not possess the current capability of a physical synchronous machine. Therefore, a primary requirement is that the control architecture employed can limit the current sufficiently quickly according to the converter's capability. The invention described above allows for at least some decoupling of these two previously compromised requirements.

[0043] In particular, the increased X / R ratio leads to improvements in expected grid behavior and voltage / angle stability. Furthermore, the higher X / R ratio forces a greater capacitive reactive current injection during far-end faults, resulting in greater voltage support during fault ride-through events. The damping of the current controller can remain unchanged without sacrificing robustness.

Claims

1. A converter (1, 7) having a converter control device (14), the converter control device (14) comprising: - Current controller (16), which receives the difference between the current setpoint (Iconvset) and the measured converter current (Iconvmeas) at the input and provides the current controller output voltage (Vact) at the output. - A damping module (17) receives the measured converter current (Iconvmeas) at its input and provides a damping voltage (Vdamp) at its output, wherein the sum of the damping voltage (Vdamp) and the converter controller output voltage (Vact) is provided to the converter modulator, characterized in that, - A virtual admittance module (19) receives at its input the difference (Vset+Vcomp-Vact) between the sum of the voltage setpoint (Vset) and the compensation voltage (Vcomp) (Vset+Vcomp) and the output voltage (Vact) of the current controller, and provides the current setpoint (Iconvset) at its output; and - Compensation module (20), which receives the current set value (Iconvset) at the input and provides the compensation voltage (Vcomp) at the output, wherein the compensation module is configured to counteract the damping effect of the damping module (17).

2. The converter (1, 7) according to claim 1, wherein, The compensation module (20) includes a converter control device model and a damping model. The converter control device model is used to determine the converter current based on the current setpoint, and the damping model is used to model the damping module (17).

3. The converter (1, 7) according to any one of the preceding claims, wherein, The converter control device (14) is configured to limit the value of the current setting value so that the value of the current setting value does not exceed a predefined current setting value limit.

4. The converter (1, 7) according to any one of the preceding claims, wherein, The virtual admittance module is a positive phase sequence virtual admittance module (35). This positive phase sequence virtual admittance module receives the difference between the sum of the positive phase sequence voltage setting value (Vset, pps) and the positive phase sequence compensation voltage (Vcomp, pps) (Vset, pps+Vcomp, pps) and the output voltage (Vact, pps) of the positive phase sequence current controller (Vset, pps) at the input terminal (Vset, pps+Vcomp, pps-Vact, pps), and provides the positive phase sequence current setting value (Iconvset, pps) at the output terminal. The compensation module is a positive phase sequence compensation module (37). The positive phase sequence compensation module receives the positive phase sequence current setting value (Iconvset, pps) at the input terminal and provides the positive phase sequence compensation voltage (Vcomp, pps) at the output terminal.

5. The converter (1, 7) according to claim 4, wherein, The converter control device further includes: - A negative phase sequence virtual admittance module (36), which receives at its input the difference between the sum of the negative phase sequence voltage setpoint (Vset, nps) and the negative phase sequence compensation voltage (Vcomp, nps) (Vset, nps+Vcomp, nps) and the output voltage (Vact, nps) of the negative phase sequence current controller (Vset, nps) (Vset, nps+Vcomp, nps-Vact, nps), and provides a negative phase sequence current setpoint (Iconvset, nps) at its output; and - Negative phase sequence compensation module (38), which receives negative phase sequence current setting value (Iconvset, nps) at the input terminal and provides negative phase sequence compensation voltage (Vcomp, nps) at the output terminal, wherein the current setting value (Iconvset) is the sum of positive phase sequence current setting value and negative phase sequence current setting value (Iconvset, pps, Iconvset, nps).

6. The converter (1, 7) according to claim 5, wherein, The current controller is a positive phase sequence current controller (41), which receives the difference between the current setpoint (Iconvset) and the measured converter current (Iconvmeas) at the input terminal and provides the output voltage (Vact, pps) of the positive phase sequence current controller at the output terminal. The converter control device also includes a negative phase sequence current controller (42), which receives the difference between the current setpoint (Iconvset) and the measured converter current (Iconvmeas) at the input terminal and provides the output voltage (Vact, nps) of the negative phase sequence current controller at the output terminal.

7. The converter (1, 7) according to any one of the preceding claims, wherein, The damping module (17) includes a transfer function.

8. The converter (1, 7) according to any one of the preceding claims, wherein, The virtual admittance module (19) includes a combination of linear transfer functions and nonlinear transfer functions.

9. The converter (1, 7) according to any one of the preceding claims, wherein, The converters (1, 7) are modular multilevel converters configured to stabilize AC high-voltage power grids.

10. A method for controlling converters (1, 7), the method comprising the steps of: - The difference between the current setpoint (Iconvset) and the measured converter current (Iconvmeas) is received at the input of the current controller (16), and the current controller output voltage (Vact) is provided at the output. - The measured converter current (Iconvmeas) is received at the input of the damping module (17), and a damping voltage (Vdamp) is provided at the output, wherein the sum of the damping voltage (Vdamp) and the converter controller output voltage (Vact) is provided to the converter modulator; - The difference (Vset+Vcomp-Vact) between the sum of the voltage setpoint (Vset) and the compensation voltage (Vcomp) (Vset+Vcomp) and the current controller output voltage (Vact) is received at the input of the virtual admittance module (19), and the current setpoint (Iconvset) is provided at the output; and - The current setting value (Iconvset) is received at the input of the compensation module (20), and the compensation voltage (Vcomp) is provided at the output, wherein the compensation module (20) cancels the damping effect of the damping module (17).

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