Dual-sampling maximum power point tracking with dynamic power limiting for power systems

Abstract

A method for operating a PV system (14) integrated into a power system (10) connected to a power grid (22) includes determining a voltage operating point for the PV system (14) based on a maximum power point tracking (MPPT) algorithm (102). If the available power output of the PV system (14) can be provided to the power grid (22), the method includes operating the PV system (14) based on the voltage operating point (106). If the maximum available power output of the PV system (14) cannot be provided to the power grid (22), the method includes applying a voltage step to the voltage operating point to drive the power output of the PV system (14) toward an external power constraint (108). A hybrid power system connected to the power grid is disclosed.

Description

Technical Field

[0001] The present subject matter relates generally to maximum power point tracking for hybrid power systems, and more particularly to methods for dual sampling maximum power point tracking of photovoltaic cells with dynamic power limiting for such hybrid power systems. Background Art

[0002] Renewable power sources such as photovoltaic (PV) cells can be integrated into other power generation applications such as wind turbines to form hybrid power systems. PV power converters receive input current at a low voltage and produce output current at a higher voltage, which can be used to generate supplemental power for the system.

[0003] Such power systems may use a maximum power point tracking (MPPT) algorithm to maximize power extraction under all conditions. More specifically, PV cells have a unique non-linear I / V curve, and therefore also a non-linear P / V curve. Figure 1 An exemplary P / V curve is shown in . As shown, the maximum value of the P / V curve coincides with the maximum power point (MPP) of the cell. Therefore, the PV cell only delivers maximum power when operating at this operating point. Due to changing weather conditions, the MPP can move quickly, resulting in module inefficiencies. Due to the dynamic nature of the MPP, the PV cell needs to actively adjust the electrical operating conditions in order to maintain maximum power output. The main goal for adjusting the operating conditions of the PV cell is to track the MPP of the cell, so the term "maximum power point tracking" is often used to describe this function.

[0004] Perturb and Observe (P&O) is the most commonly used MPPT algorithm in such power systems due to its ease of implementation. In the P&O method, the system controller adjusts the voltage applied to the PV array by small amounts and measures the power; if the power increases, further adjustments in that direction are attempted until the power stops increasing. Therefore, an integral part of any P&O method is the size of the perturbation (in this case, a voltage step) applied to the PV power converter output voltage.

[0005] However, the P&O approach has some limitations, including but not limited to oscillations around the MPP in steady-state operation, slow response speed, and tracking in an erroneous manner under rapidly changing irradiance / atmospheric conditions. Such limitations usually translate into a loss of maximum power output of the PV power system. In addition, in some cases, PV systems must coexist with other energy sources. Therefore, coordination between such sources is inevitable, typically in the form of subsystem priorities and / or capacity usage rules.

[0006] The dual sampling MPPT provides an improved P&O method with superior performance under dynamic atmospheric conditions, which reacts after twice the update time in order to select the correct operating point. More specifically, as Figure 2 As shown in , the operating point sequence is used to illustrate how the dual sampling MPPT algorithm works. As shown, after the first sampling period, the algorithm calculates the power value and the incremental power. This causes the PV cell to operate at point A after the PV power converter voltage causes a positive incremental step. Since the new power change is negative, the direction must be reversed in order to pursue the MPP. The next reduction in voltage will bring the operating point to B after the time period t0 to t1, however, the sudden irradiance increase that coincides with the reduction in voltage step leads to point C. It is important to note that the traditional MPPT interpretation is that a voltage reduction causes a power increase (i.e., ΔP1 is positive), and the current operating point moves up in the curve after the target MPP. Therefore, a reduction in voltage is again required. This judgment is incorrect because the effects of voltage and irradiance cannot be independently discriminated and acted upon. Therefore, the dual sampling MPPT algorithm waits for an additional updated power value (e.g., operating point D) and calculates a second incremental power (e.g., ΔP2). If the power shift on the power-voltage curve is approximately linear, the power change due to the voltage step alone can be estimated by subtracting ΔP2 from ΔP1. Having a better approximation for the individual effects of increasing the output voltage of the PV power converter allows for more efficient MPP tracking. More specifically, still referring to Figure 2 And assuming the effect is a power drop, after the time interval t0 to t2, the previous voltage step must be reversed, bringing the operating condition to the right of point D. If the irradiance continues to pull up the power-voltage curve and the same set of calculations continues, the dual-sampling MPPT algorithm will bring the operating point from E to the target MPP.

[0007] Thus, systems and methods for integrating a dynamic MPPT algorithm for a PV system (such as the dual sampling MPPT described above) with an external power constraint (representing the minimum available margin in the components interconnecting the PV source to the rest of the system) would be welcome in the art. Accordingly, the present disclosure is directed to systems and methods for employing variable voltage steps when the MPPT voltage approaches the aforementioned external power constraint. Summary of the invention

[0008] Aspects and advantages of the invention will be set forth in part in the following description, or may be obvious from the description, or may be learned through practice of the invention.

[0009] In one aspect, the present subject matter discloses a method for operating a PV system that is integrated into a power system connected to a power grid. The method includes determining a voltage operating point for the PV system based on a maximum power point tracking (MPPT) algorithm. If an available power output of the PV system can be provided to the power grid, the method includes operating the PV system based on the voltage operating point. If the maximum available power output of the PV system cannot be provided to the power grid, the method includes applying a voltage step to the voltage operating point to drive the power output of the PV system toward an external power constraint.

[0010] In one embodiment, the method includes applying a voltage step to an output voltage of a PV power converter of a PV system to drive the power output of the PV system toward an external power constraint. In such embodiments, the voltage step may correspond to a gain proportional to a difference between two power limit points as the difference approaches zero.

[0011] In another embodiment, the step of operating the PV system based on the voltage operating point may include maintaining a voltage step of a PV power converter of the PV system at a constant value. In further embodiments, the external power constraint may correspond to a minimum available margin in one or more external components interconnecting the PV system to the power system. In such embodiments, the power system may be a wind turbine power system. Thus, the one or more external components may correspond to a power limiter of a power converter of the wind turbine power system. In further embodiments, the power system may include a gas turbine power system, an energy storage system, and / or any other power system or combination thereof.

[0012] In several embodiments, the MPPT algorithm may include a single sampling MPPT algorithm. In such embodiments, the MPPT algorithm may be based on a perturb & observe (P&O) algorithm. Alternatively, the MPPT algorithm may include a dual sampling MPPT algorithm.

[0013] In another aspect, the present disclosure relates to a hybrid power system connected to a power grid. The hybrid power system includes a wind turbine power system, a photovoltaic (PV) system integrated into the wind turbine power system, and a system controller communicatively coupled to the wind turbine power system and the PV system. The system controller is configured to perform one or more operations, including but not limited to, determining a voltage operating point for the PV system based on an MPPT algorithm when the available power output of the PV system can be provided to the power grid, operating the PV system based on the voltage operating point, and applying a voltage step to the voltage operating point when the maximum available power output of the PV system cannot be provided to the power grid to drive the power output of the PV system toward an external power constraint.

[0014] In one embodiment, the wind turbine power system may include a power converter having a dynamic power limiter. In such embodiments, the power constraint may be equal to the power limit of the power limiter. It should be understood that the hybrid power system may also include any of the additional features and / or steps described herein.

[0015] In yet another aspect, the present disclosure relates to a method for operating a photovoltaic (PV) system that is integrated into a power system connected to a power grid. The method includes using an MPPT algorithm to track a maximum power point of the PV system. In addition, the method includes maintaining a voltage step of the PV system at a constant value as long as the maximum power point of the MPPT algorithm does not intersect an external power constraint of the power system. However, if the maximum power point of the MPPT algorithm intersects an external power constraint of the power system, the method includes applying a voltage step to an output voltage of a PV power converter of the PV system. It should be understood that the hybrid power system may also include any of the additional features and / or steps described herein.

[0016] These and other features, aspects and advantages of the present invention will become better understood with reference to the following description.The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the present invention and, together with the description, serve to explain the principles of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] A complete and enabling disclosure of the present invention, including the best mode thereof, to one of ordinary skill in the art is set forth in the specification with reference to the accompanying drawings, in which:

[0018] Figure 1 A graph showing one embodiment of power (y-axis) versus voltage (x-axis) for a PV system operating according to a single sampling MPPT algorithm;

[0019] Figure 2 A graph showing one embodiment of power (y-axis) versus voltage (x-axis) for a PV system operating according to a dual sampling MPPT algorithm;

[0020] Figure 3 A schematic diagram showing one embodiment of a hybrid power system including a wind farm and a PV system according to the present disclosure;

[0021] Figure 4 A perspective view showing one embodiment of a wind turbine according to the present disclosure;

[0022] Figure 5 A block diagram illustrating one embodiment of a hybrid power system according to the present disclosure;

[0023] Figure 6A schematic diagram showing one embodiment of a controller according to the present disclosure;

[0024] Figure 7 A flow chart showing one embodiment of a method for operating a PV system integrated into a wind turbine connected to a power grid according to the present disclosure;

[0025] Figure 8 A flow chart illustrating one embodiment of the interfacing aspects of a hybrid power system according to the present disclosure, and in particular illustrating a power limiter of a wind turbine interfacing with a dual sampling MPPT of a PV system; and

[0026] Fig. 9 A flow chart showing another embodiment of a method for operating a PV system integrated into a wind turbine connected to a power grid according to the present disclosure. DETAILED DESCRIPTION

[0027] Reference will now be made in detail to embodiments of the present invention, one or more examples of which are shown in the drawings. Each example is provided as an explanation of the present invention, not a limitation of the present invention. In fact, it will be apparent to those skilled in the art that various modifications and variations may be made in the present invention without departing from the scope or spirit of the present invention. For example, a feature shown or described as a part of an embodiment may be used with another embodiment to produce yet another embodiment. Therefore, it is intended that the present invention covers such modifications and variations as fall within the scope of the appended claims and their equivalents.

[0028] Refer to the figure, Figure 3 A schematic diagram of one embodiment of a hybrid power system 10 connected to a power grid 22 according to the present disclosure is shown. As shown in the illustrated embodiment, the hybrid power system 10 includes a plurality of wind turbines 12, a plurality of photovoltaic (PV) systems 14, and a system controller 16. More particularly, as shown, one or more of the wind turbines 12 may be individually coupled to a group of PV systems 14 (only one of which is shown). Additionally, as shown in the illustrated embodiment, the hybrid power system 10 includes twelve wind turbines 12. However, in other embodiments, the hybrid power system 10 may include any other number of wind turbines 12, such as less than twelve wind turbines 12 or more than twelve wind turbines 12. Additionally, as shown, each of the PV systems 14 may include any suitable number of PV devices 15 or solar modules, PV power converters 17, and PV controllers 19. Furthermore, in a typical embodiment, each PV device 15 may include a solar panel having a plurality of solar cells that generates electrical power by converting light into electricity using, for example, semiconductor materials that exhibit a photovoltaic effect.

[0029] In addition, as shown, the system controller 16 may be communicatively coupled to the PV system 14 (particularly the PV controller 19) and the wind turbine 12 via their respective individual turbine controllers 18 via a wired connection, such as via a suitable communication link 20 or network (e.g., a suitable cable). Alternatively, the system controller 16 may be communicatively coupled to the PV system 14 and / or the turbine controller 18 via a wireless connection, such as by using any suitable wireless communication protocol known in the art. In addition, for each of the individual wind turbines 12 within the hybrid power system 10, the system controller 16 may be generally configured similarly to the turbine controller 18.

[0030] In addition, as shown, the system controller 16 may be communicatively coupled to the PV system 14 (particularly the PV controller 19) and the wind turbine 12 via their respective individual turbine controllers 18 via a wired connection, such as via a suitable communication link 20 or network (e.g., a suitable cable). Alternatively, the system controller 16 may be communicatively coupled to the PV system 14 and / or the turbine controller 18 via a wireless connection, such as by using any suitable wireless communication protocol known in the art. In addition, for each of the individual wind turbines 12 within the hybrid power system 10, the system controller 16 may be generally configured similarly to the turbine controller 18.

[0031] Still refer to Figure 3 , each of the wind turbines 12 may also include one or more sensors, such as sensors 24, 26. Thus, the sensors 24, 26 are configured to measure various parameters, including but not limited to operational and / or environmental conditions. For example, as shown, the wind turbine 12 includes a wind sensor 24, such as an anemometer or any other suitable device, which is configured to measure wind speed or any other wind parameter. The wind parameter includes information about at least one of the following or a combination thereof: gusts, wind speed, wind direction, wind acceleration, wind turbulence, wind shear, wind turning, wake, SCADA information, or the like. In addition, the wind turbine 12 may also include one or more additional sensors for monitoring additional operating parameters thereof. In addition, each sensor 24, 26 may be a separate sensor or may include multiple sensors. The sensors 24, 26 may be any suitable sensor having any suitable location within or away from the wind turbine 12 that allows the wind turbine 12 to function as described herein. In some embodiments, the sensors 24 , 26 are coupled to one of the controllers 16 , 18 described herein for transmitting measurements to the controller for processing thereof.

[0032] Now refer to Figure 4, each wind turbine 12 generally includes a tower 32 extending from a support surface 34, a nacelle 36 mounted on the tower 32, and a rotor 38 coupled to the nacelle 36. The rotor 38 includes a rotatable hub 40 and at least one rotor blade 42 coupled to the hub 40 and extending outwardly from the hub 40. For example, in the illustrated embodiment, the rotor 38 includes three rotor blades 42. However, in alternative embodiments, the rotor 38 may include more or less than three rotor blades 42. Each rotor blade 42 may be spaced around the hub 40 to facilitate rotating the rotor 38 to enable kinetic energy to be converted from the wind into usable mechanical energy, and subsequently converted into electrical energy. For example, the hub 40 may be rotatably coupled to a generator 25 ( 40 ) positioned within the nacelle 36. Figure 5 ) to allow electrical energy to be generated. Additionally, as shown, the turbine controller 18 described herein may be centralized within the nacelle 36. However, it should be appreciated that the turbine controller 18 may be disposed at any location on or in the wind turbine 12, at any location on the support surface 34, or generally at any other location.

[0033] Now refer to Figure 5 , a block diagram of one embodiment of a hybrid power system 10 of the present disclosure is shown. As shown, the hybrid power system 10 includes an energy source, such as a generator 25 of a wind turbine 12. The system 10 also includes a turbine power converter 28 that receives variable frequency electrical power 39 generated by the generator 25 and converts the electrical power 39 into terminal power 41 suitable for transmission on the power grid 22. In addition, as shown, the turbine power converter 28 is configured to receive a control signal 45 from the converter interface controller 30. Thus, the control signal 45 is based on a sensed operating condition or operating characteristic of the power system 10 as described herein, and is used to control the operation of the turbine power converter 28. Examples of measured operating conditions may include, but are not limited to, a terminal grid voltage (V t )43, PLL error, stator bus voltage, rotor bus voltage and / or current. For example, as shown, the terminal voltage (V t )43. Therefore, as shown, the terminal voltage (V t ) The grid voltage feedback signal 47 represented by 43 is sent to the power limiter 35 and / or the phase locked loop 37. Therefore, the power limiter 35 can generate a power command signal 49 based at least in part on the feedback signal 47, and transmit the power command signal 49 to the converter interface controller 30.

[0034] The various controllers 16, 18, 19, 30 described herein may generally include any suitable processing unit configured to perform the methods, steps, operations, calculations, etc. described herein. Thus, in several embodiments, the controllers 16, 18, 19, 30 may include suitable computer-readable instructions that, when implemented, configure the controllers 16, 18, 19, 30 to perform various different actions, such as transmitting and executing wind turbine control signals and / or commands. By transmitting and executing system control signals and / or commands, the controllers 16, 18, 19, 30 may generally be configured to control various operating modes (e.g., startup or shutdown sequences) and / or components of the hybrid power system 10.

[0035] Now refer to Figure 6 , a block diagram of one embodiment of a controller is shown, such as one of the controllers 16, 18, 19, 30 described herein. In general, each of the controllers 16, 18, 19, 30 may include a computer or any other suitable processing unit. Therefore, in several embodiments, each of the controllers 16, 18, 19, 30 may include one or more processors 44 and associated memory devices 46, which are configured to perform various computer-implemented functions (e.g., perform the methods, steps, operations, calculations, etc. disclosed herein). As used herein, the term "processor" refers not only to integrated circuits that are considered to be included in a computer in the art, but also to controllers, microcontrollers, microcomputers, programmable logic controllers (PLCs), application-specific integrated circuits, and other programmable circuits. In addition, the memory device 46 may generally include memory elements, including but not limited to: computer-readable media (e.g., random access memory (RAM)), computer-readable non-volatile media (e.g., flash memory), floppy disks, compact disk-read only memory (CD-ROM), magneto-optical disks (MODs), digital versatile disks (DVDs), and / or other suitable memory elements. Such memory devices 46 may generally be configured to store suitable computer-readable instructions that, when executed by the processor 44 of the controller 16, 18, 19, 30, configure the controller 16, 18, 19, 30 to perform various functions. The memory device 46 may also be used to store temporary input and output variables and other immediate information during execution of the computer-readable instructions by the processor 44.

[0036] In addition, as shown, each of the controllers 16, 18, 19, 30 may also include a communication module 48 to facilitate communication between each of the controllers 16, 18, 19, 30 and various components of the hybrid power system 10. In several embodiments, the communication module 48 may include a sensor interface 50 to allow the sensors 24, 26 of the hybrid power system 10 to transmit output data (e.g., operating temperature measurements, power output measurements, etc.) to each of the controllers 16, 18, 19, 30. Thus, as shown, each sensor 24, 26 may be communicatively coupled to each of the controllers 16, 18, 19, 30 via the sensor interface 50. For example, in one embodiment, the sensors 24, 26 may be communicatively coupled to the sensor interface 50 via a wired connection, such as by coupling the sensors 24, 26 to the sensor interface 50 via a cable or other suitable communication link. Alternatively, the sensors 24, 26 may be communicatively coupled to the sensor interface 50 via a wireless connection. For example, each sensor 24, 26 may be equipped with a suitable antenna for transmitting output data to each of the controllers 16, 18, 19, 30 via any suitable wireless communication protocol. In such embodiments, the communication module 48 may also include a suitable antenna for receiving data transmissions and / or for otherwise wirelessly communicating with the sensors 24, 26. It should be appreciated that a suitable sensor interface 50 may include, for example, one or more analog-to-digital converters configured to convert analog signals into digital signals that can be used by the processor 44 of the controller 16, 18, 19, 30.

[0037] Now refer to Figure 7 , showing a method for operating at least one PV system (such as Figure 3 14). As shown at 102, the method 100 includes determining a voltage operating point for the PV system 14 based on an MPPT algorithm. For example, in one embodiment, the MPPT algorithm may include a single-sample MPPT algorithm. In such an embodiment, the MPPT algorithm may be based on a perturbation & observation (P&O) algorithm. In an alternative embodiment, Figure 8 As shown in FIG. 1 , the MPPT algorithm may include a dual sampling MPPT algorithm 52, referred to herein as Figure 2 The dual sampling MPPT algorithm 52 is further explained and described in detail below. In addition, as shown, the MPPT algorithm 52 receives various inputs, such as the power measured at the DC chopper terminals of the power converter 28 (eg, P PV ) and / or voltage step V STEP(ie, the size of the increment applied to the DC chopper voltage reference, performing each first half of the algorithm.) Thus, as shown, the output of the MPPT algorithm 52 is the MPPT voltage reference (eg, ref_V_pv).

[0038] As shown at 104, method 100 includes determining whether all available power output of PV system 14 can be provided to the power grid. If so, method 100 includes operating PV system 14 based on the voltage operating point, as shown at 106. More particularly, in such embodiments, PV controller 19 may be configured to maintain the output voltage of PV power converter 17 of PV system 14 at a constant value.

[0039] As shown at 108, if all available power output of the PV system 14 cannot be provided to the power grid 22, the method 100 includes applying a voltage step to the voltage operating point to drive the power output of the PV system 14 toward the external power constraint. More specifically, Figure 8 , method 100 may include applying a voltage step 56 to the output voltage of a PV power converter 17 of a PV system 14 to drive the power output of the PV system 14 toward the external power constraint. Thus, the voltage step 56 is used when transitioning between the dynamic power limit and the MPPT target. In such embodiments, the voltage step 56 may correspond to a gain that varies linearly with the power difference between the PV converter output and the external constraint reference as the difference approaches zero.

[0040] In other embodiments, the external power constraint may correspond to a minimum available margin in one or more external components interconnecting the PV device 14 with each of the wind turbines 12 of the hybrid power system 10. For example, Figure 8 , the external component may correspond to the power limiter 35 of the wind turbine power system 12. More specifically, as shown at 54, the turbine controller (TC) generates a power limit or target independent of the DC chopper rating limit, so the smaller of the two in the power limiter 35 becomes the reference external to the MPPT logic.

[0041] Now refer to Fig. 9, a flow chart showing another embodiment of a method 200 for operating a PV system 14 integrated into a wind turbine power system connected to a power grid. As shown at 202, the method 200 includes using an MPPT algorithm to track the maximum power point of the PV system 14. As shown at 204, the method 200 includes maintaining a voltage step of the PV system 14 at a constant value as long as the maximum power point of the MPPT algorithm does not intersect an external power constraint of the power system. As shown at 206, if the maximum power point of the MPPT algorithm intersects the external power constraint of the power system (i.e., the maximum power point becomes equal to or greater than the power constraint, such that the incremental power used by the voltage step generator 56 is a negative value), the method 200 includes applying a voltage step to the output voltage of a PV power converter of the PV system 14.

[0042] This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any device or system and performing any combined method. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they include structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal language of the claims.

[0043] Component List

[0044] Reference Symbol Component

[0045] 10 Hybrid Power System

[0046] 12 Wind Turbines

[0047] 14 PV system

[0048] 15 PV installation

[0049] 16 System Controller

[0050] 17 PV Power Converter

[0051] 18 Turbine controller

[0052] 19 PV controller

[0053] 20 links

[0054] 22 Power Network

[0055] 24 sensors

[0056] 25 Generator

[0057] 26 sensors

[0058] 28 Turbine power converter

[0059] 30 Converter Controller

[0060] 32 Tower

[0061] 34 Support surface

[0062] 35 Power Limiter

[0063] 36 Cabin

[0064] 37 Phase-locked loop

[0065] 38 rotors

[0066] 39 Electric power

[0067] 40 hub

[0068] 41 Terminal Power

[0069] 42 rotor blades

[0070] 43 Terminal voltage

[0071] 44 processors

[0072] 45 control signal

[0073] 46 memory device

[0074] 47 Grid voltage feedback signal

[0075] 48 communication modules

[0076] 49 Power command signal

[0077] 50 sensor interface

[0078] 52Dual sampling MPPT algorithm

[0079] 54Minimum

[0080] 56 Voltage Step

[0081] 58 output

[0082] 100 Methods

[0083] 102 Methods and Steps

[0084] 104 Methods and Steps

[0085] 106 Methods and Steps

[0086] 108 Methods and Steps

[0087] 200 Methods

[0088] 202 Methods and Steps

[0089] 204 Methods and Steps

[0090] 206 Methods and Steps

[0091] 208 method steps.

Claims

1. A method for operating a photovoltaic (PV) system, the system being integrated into a power system connected to a power grid, the method comprising: determining a voltage operating point for the PV system based on a maximum power point tracking (MPPT) algorithm; operating the PV system based on the voltage operating point if available power output of the PV system is available to the power grid; as well as If the maximum available power output of the PV system cannot be provided to the power grid, a voltage step is applied to the output voltage of a PV power converter of the PV system to drive the power output of the PV system toward an external power constraint, wherein the voltage step includes a gain that varies linearly with a power difference between the PV power converter output and an external power constraint reference as the power difference approaches zero.

2. The method according to claim 1, characterized in that Operating the PV system based on the voltage operating point also includes maintaining a voltage step of a PV power converter of the PV system at a constant value.

3. The method according to claim 1, characterized in that The external power constraint includes a minimum available margin in one or more external components interconnecting the PV system with the power system.

4. The method according to claim 3, characterized in that: The power system includes a wind turbine power system, a gas turbine power system, an energy storage system, or a combination thereof.

5. The method according to claim 4, characterized in that The one or more external components include a power limiter of a power converter of the wind turbine power system.

6. The method according to claim 1, characterized in that The MPPT algorithm includes a single sampling MPPT algorithm.

7. The method according to claim 6, characterized in that The MPPT algorithm is based on the Perturb & Observe (P&O) algorithm.

8. The method according to claim 1, characterized in that The MPPT algorithm includes a double sampling MPPT algorithm.

9. A hybrid power system connected to a power grid, comprising: Wind turbine power systems; a photovoltaic (PV) system integrated into the wind turbine power system; as well as a system controller communicatively coupled to the wind turbine power system and the PV system, the system controller configured to perform one or more operations comprising: determining a voltage operating point for the PV system based on a maximum power point tracking (MPPT) algorithm; operating the PV system based on the voltage operating point if available power output of the PV system is available to the power grid; and If the maximum available power output of the PV system cannot be provided to the power grid, a voltage step is applied to the output voltage of a PV power converter of the PV system to drive the power output of the PV system toward an external power constraint, wherein the voltage step includes a gain that varies linearly with a power difference between the PV power converter output and an external power constraint reference as the power difference approaches zero.

10. The hybrid power system according to claim 9, characterized in that: The wind turbine power system also includes a power converter including a dynamic power limiter, wherein the power constraint is equal to a power limit of the power limiter.

11. The hybrid power system according to claim 9, characterized in that: Operating the PV system based on the voltage operating point also includes maintaining a voltage step of a PV power converter of the PV system at a constant value.

12. The hybrid power system according to claim 9, characterized in that: The power constraint includes a minimum available margin in one or more external components interconnecting the PV system with the wind turbine power system.

13. A method for operating a photovoltaic (PV) system, the system being integrated into a power system connected to a power grid, the method comprising: Tracking the maximum power point of the PV system using a maximum power point tracking (MPPT) algorithm; maintaining a voltage step of the PV system at a constant value as long as a maximum power point of the MPPT algorithm does not intersect an external power constraint of the power system; as well as If a maximum power point of the MPPT algorithm intersects one or more of the external power constraints of the power system, a variable voltage step is applied to an output voltage of a PV power converter of the PV system, wherein the variable voltage step includes a gain that varies linearly with a power difference between the PV power converter output and an external power constraint reference as the power difference approaches zero.

14. The method according to claim 13, characterized in that The external power constraint includes a minimum available margin in one or more external components interconnecting the PV system with the power system.

15. The method according to claim 14, characterized in that The power system includes a wind turbine power system, a gas turbine power system, an energy storage system, or a combination thereof.

16. The method according to claim 15, characterized in that The one or more external components include a power limiter of a power converter of the wind turbine power system.

17. The method according to claim 13, characterized in that The MPPT algorithm includes a double sampling MPPT algorithm.

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