Optical storage power station control strategy digital real-time simulation test method and system

Abstract

The invention provides an optical storage power station control strategy digital real-time simulation test method and system, and belongs to the field of power grid simulation, and the method comprises the steps: importing an optical storage power station simulation model into an RT1000 digital real-time simulation device, and simulating the operation process of an optical storage power station based on the operation data of the optical storage power station; in the simulation process, according to the output voltage and the output current of the photovoltaic array, the maximum power of the photovoltaic array and the reference voltage of a direct-current link are determined by adopting an incremental conductance maximum power point tracking algorithm; controlling the working mode of the main voltage source converter according to the power grid voltage angle, the power grid frequency and the main load induced voltage; based on the working mode of the main voltage source converter, the on-off of each switch in the main voltage source converter and the auxiliary voltage source converter is controlled by adopting a self-adaptive current control algorithm; and the on-off of each switch in the bidirectional converter is controlled by adopting a conductance maximum power point tracking algorithm and a PI controller. According to the invention, the simulation efficiency and precision of the control strategy of the optical storage power station are improved.

Description

Technical Field

[0001] The present invention relates to the field of power grid simulation, and in particular to a digital real-time simulation test method and system for a photovoltaic power station control strategy. Background Art

[0002] In the power system, power generation based on solar photovoltaic power generation is clean and economical; battery energy storage is a storage system used to compensate for the intermittent problems of renewable energy and loads, and to supply power to the load network in the event of a power grid outage; microgrid systems are usually interconnected with the main power grid, and this connection is usually achieved through a three-phase AC power grid. The power system needs to be verified through simulation to verify its effectiveness. Traditional simulation methods cannot achieve real-time simulation, resulting in a large deviation between the simulation results and the actual operating conditions, and the simulation efficiency and accuracy are low. Summary of the invention

[0003] The purpose of the present invention is to provide a digital real-time simulation test method and system for a photovoltaic power station control strategy, which can improve the simulation efficiency and accuracy of the photovoltaic power station control strategy.

[0004] To achieve the above object, the present invention provides the following solutions:

[0005] A digital real-time simulation test method for a photovoltaic power station control strategy, comprising:

[0006] Obtaining the operation data of the photovoltaic power station;

[0007] Establishing a photovoltaic power station simulation model; the photovoltaic power station simulation model includes a main photovoltaic array, an auxiliary photovoltaic array, a main voltage source converter, an auxiliary voltage source converter, a main load, an auxiliary load, a bidirectional converter, a common coupling switch and a three-phase power grid; the main photovoltaic array, the bidirectional converter, the main voltage source converter, the main load, the common coupling switch and the three-phase power grid are connected in sequence; the auxiliary photovoltaic array, the auxiliary voltage source converter, the auxiliary load, the common coupling switch and the three-phase power grid are connected in sequence;

[0008] The photovoltaic power station simulation model is imported into the RT1000 digital real-time simulation device, and the operation process of the photovoltaic power station is simulated based on the operation data of the photovoltaic power station;

[0009] During the simulation process, according to the output voltage and output current of the main photovoltaic array, the maximum power of the main photovoltaic array and the main DC link reference voltage are determined by using the incremental conductance maximum power point tracking algorithm; according to the output voltage and output current of the auxiliary photovoltaic array, the maximum power of the auxiliary photovoltaic array and the auxiliary DC link reference voltage are determined by using the incremental conductance maximum power point tracking algorithm;

[0010] Controlling the working mode of the main voltage source converter according to the grid voltage angle, grid frequency and main load induced voltage; the working mode is a grid-connected mode or an off-grid mode;

[0011] Based on the working mode of the main voltage source converter, an adaptive current control algorithm is adopted to control the on and off of each switch in the main voltage source converter according to the maximum power of the main photovoltaic array;

[0012] Adopting an adaptive current control method to control the on and off of each switch in the auxiliary voltage source converter according to the maximum power of the auxiliary photovoltaic array and the auxiliary DC link reference voltage;

[0013] A conductance maximum power point tracking algorithm and a PI controller are used to control the on and off of each switch in the bidirectional converter according to the main DC link reference voltage.

[0014] To achieve the above object, the present invention also provides the following solution:

[0015] A digital real-time simulation test system for a photovoltaic power station control strategy, comprising: a model building module and an RT1000 digital real-time simulation device;

[0016] The model building module is used to obtain the operation data of the photovoltaic power station and establish a simulation model of the photovoltaic power station; the simulation model of the photovoltaic power station includes a main photovoltaic array, an auxiliary photovoltaic array, a main voltage source converter, an auxiliary voltage source converter, a main load, an auxiliary load, a bidirectional converter, a common coupling switch and a three-phase power grid; the main photovoltaic array, the bidirectional converter, the main voltage source converter, the main load, the common coupling switch, and the three-phase power grid are connected in sequence; the auxiliary photovoltaic array, the auxiliary voltage source converter, the auxiliary load, the common coupling switch, and the three-phase power grid are connected in sequence;

[0017] The RT1000 digital real-time simulation device is used to simulate the operation process of the photovoltaic power station based on the operation data of the photovoltaic power station, and in the simulation process, according to the output voltage and output current of the main photovoltaic array, the incremental conductance maximum power point tracking algorithm is used to determine the maximum power of the main photovoltaic array and the main DC link reference voltage, and according to the output voltage and output current of the auxiliary photovoltaic array, the incremental conductance maximum power point tracking algorithm is used to determine the maximum power of the auxiliary photovoltaic array and the auxiliary DC link reference voltage; according to the grid voltage angle, grid frequency and main load induced voltage, the working mode of the main voltage source converter is controlled; the working mode is a grid-connected mode or an off-grid mode; based on the working mode of the main voltage source converter, an adaptive current control algorithm is used to control the on-off of each switch in the main voltage source converter according to the maximum power of the main photovoltaic array; an adaptive current control method is used to control the on-off of each switch in the auxiliary voltage source converter according to the maximum power of the auxiliary photovoltaic array and the auxiliary DC link reference voltage; a conductance maximum power point tracking algorithm and a PI controller are used to control the on-off of each switch in the bidirectional converter according to the main DC link reference voltage.

[0018] According to the specific embodiments provided by the present invention, the present invention discloses the following technical effects: the present invention performs simulation test on the operation process of the photovoltaic power station through the RT1000 digital real-time simulation device, thereby improving the real-time performance of the simulation results; during the simulation test, an incremental conductance maximum power point tracking algorithm, an adaptive current control algorithm and a PI controller are used to control the main voltage source converter, the auxiliary voltage source converter and the bidirectional converter, thereby improving the robustness of the simulation test of the photovoltaic power station, thereby improving the simulation efficiency and accuracy of the control strategy of the photovoltaic power station. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0020] Figure 1 A flow chart of a digital real-time simulation test method for a photovoltaic power station control strategy provided by the present invention;

[0021] Figure 2 This is a schematic diagram of the simulation model of the photovoltaic power station;

[0022] Figure 3 Simulate schematics for digital real-time simulation tools;

[0023] Figure 4 Schematic diagram of mode conversion of main voltage source converter;

[0024] Figure 5 is a control schematic diagram of the main voltage source converter;

[0025] Figure 6 is a control schematic diagram of an auxiliary voltage source converter;

[0026] Figure 7 is a control schematic diagram of a bidirectional converter;

[0027] Figure 8 It is a simulation flow chart.

[0028] Explanation of symbols: 1-main photovoltaic array, 2-auxiliary photovoltaic array, 3-main voltage source converter, 4-auxiliary voltage source converter, 5-bidirectional converter, 6-main load, 7-auxiliary load, 8-common coupling switch, 9-three-phase grid, 10-RT1000 workstation, 11-RT1000 model operation unit, 12-visualization tool. DETAILED DESCRIPTION

[0029] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0030] The purpose of the present invention is to provide a digital real-time simulation test method and system for the control strategy of a photovoltaic power station with storage, and to simulate and test the control strategy of the photovoltaic power station with an RT1000 digital real-time simulation device to ensure the real-time and accuracy of the test data.

[0031] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0032] Embodiment 1

[0033] like Figure 1 As shown, this embodiment provides a digital real-time simulation test method for a photovoltaic power station control strategy, including:

[0034] Step 100: Obtaining the operation data of the photovoltaic power station.

[0035] Step 200: Establish a simulation model of a photovoltaic power station.

[0036] like Figure 2As shown, the simulation model of the photovoltaic power station includes a main photovoltaic array 1, an auxiliary photovoltaic array 2, a main voltage source converter 3, an auxiliary voltage source converter 4, a main load 6, an auxiliary load 7, a bidirectional converter 5, a common coupling switch 8 and a three-phase power grid 9.

[0037] The main photovoltaic array 1, the bidirectional converter 5, the main voltage source converter 3, the main load 6, the common coupling switch 8, and the three-phase power grid 9 are connected in sequence.

[0038] The auxiliary photovoltaic array 2, the auxiliary voltage source converter 4, the auxiliary load 7, the common coupling switch 8, and the three-phase power grid 9 are connected in sequence.

[0039] In a single-stage configuration, the incremental conductance maximum power point tracking algorithm (MPPT) is used to extract the peak power of two independent photovoltaic arrays, which is absorbed by the DC link of the main voltage source converter 3 and the auxiliary voltage source converter 4. On the DC link of the main voltage source converter 3, the energy storage battery is connected through a dc-dc bidirectional converter 5, which manages the charging and discharging of the battery energy storage according to the base load and peak load requirements and regulates the DC link voltage of the main voltage source converter 3. At the common coupling point, the VSCs terminals are connected through an interface inductor L f The parallel integration also connects different ripple filters (R f , C f ) of different loads. The grid is connected through a power electronic switch at a common coupling point. The three-phase nonlinear load consists of a three-phase diode rectifier in which a resistive and inductive load are connected in series. The frequency and voltage of the microgrid are maintained by the grid at the common coupling point. Under normal circumstances, the main voltage source converter 3 operates through current control in the grid interactive mode. However, in the event of a grid interruption / failure, the main voltage source converter 3 will operate in the off-grid mode using a voltage control algorithm to ensure that the power distributed to the load network is continuous. In the off-grid mode, the voltage and frequency of the microgrid are maintained by the main voltage source converter 3 through voltage control technology, and the auxiliary voltage source converter 4 at this time continues to operate through a current control algorithm.

[0040] Step 300: Import the photovoltaic power station simulation model into the RT1000 digital real-time simulation device, and simulate the operation process of the photovoltaic power station based on the photovoltaic power station operation data.

[0041] During the simulation test of the present invention, the simulation environment of the RT1000 digital real-time simulation device is configured as follows:

[0042] 1) Modeling environment: Matlab / Simulink simulation modeling.

[0043] 2) Simulation mode: electromagnetic transient.

[0044] 3) Processor: 32 cores, 2.6 GHz.

[0045] 4)Simulation step length: 50us.

[0046] 5) Analog input: 12-bit analog input, 64 channels, input voltage ±10V.

[0047] 6) Analog output: Analog output with 12-bit accuracy, 128 channels, and output voltage of ±10V.

[0048] 7) Switch input: 32 channels, input voltage 24V.

[0049] 8) Switching output: 32 channels, output voltage 24V.

[0050] 9) Communication protocol: IEC 104, ModBus, IEC 61850 protocol.

[0051] 10) Observer: Oscilloscope and visualization tools.

[0052] The digital real-time simulation device RT1000 is used to simulate a new type of photovoltaic power station, including photovoltaic power generation, battery energy storage, three-phase grid interaction, etc. RT1000 can run power system simulation at real-time speed, that is, the simulation speed is consistent with the actual system operation speed. At the same time, RT1000 provides an intuitive and friendly graphical user interface and interactive simulation environment, supports real-time data visualization and control, and can help users intuitively observe and analyze simulation results, such as Figure 3 It can help optimize the design and control strategy of the microgrid system to ensure its reliability and efficiency in different situations.

[0053] Step 400: During the simulation process, the maximum power of the main photovoltaic array 1 and the main DC link reference voltage are determined by using an incremental conductance maximum power point tracking algorithm according to the output voltage and output current of the main photovoltaic array 1, and the maximum power of the auxiliary photovoltaic array 2 and the auxiliary DC link reference voltage are determined by using an incremental conductance maximum power point tracking algorithm according to the output voltage and output current of the auxiliary photovoltaic array 2.

[0054] Specifically, during the simulation, the output voltage and output current of the two photovoltaic arrays are monitored in real time, and the current power value is calculated. The MPPT controller compares the current power value with the power value at the previous moment, and increases the power according to the comparison result to keep the output voltage of the photovoltaic array near the maximum power point.

[0055] MPPT obtains the maximum power of the photovoltaic array connected to the DC link of the main voltage source converter 3 and the auxiliary voltage source converter 4 respectively. The output current and output voltage of the main photovoltaic array 1 are the inputs of the MPPT control of the main voltage source converter 3. The output of MPPT is the output voltage of the main photovoltaic array at the maximum power, which is used as the main DC link reference voltage V * dc1 Similarly, the output current and output voltage of the auxiliary photovoltaic array are the inputs of the MPPT control of the auxiliary voltage source converter. The output of the MPPT is the output voltage of the auxiliary photovoltaic array at maximum power, which serves as the auxiliary DC link reference voltage V * dc2 .

[0056] Step 500: Control the working mode of the main voltage source converter according to the grid voltage angle, grid frequency and main load induction voltage. The working mode is a grid-connected mode or an off-grid mode.

[0057] Specifically, according to the main load induction voltage (v La1 、v Lb1 、v Lc1 ) Determine the voltage angle θ at the common coupling point l According to the common coupling point voltage angle θ l , grid voltage angle θ g and grid frequency f g , a PI controller is used to control the working mode of the main voltage source converter.

[0058] 1) Evaluate the grid voltage angle θ l and grid frequency f g . Common coupling point voltage voltage angle θ l The voltage induced by the main load (v La1 、v Lb1 、v Lc1 ) calculated.

[0059] 2) The phase angle error (θ g -θ l ) is transmitted to the PI controller, and the PI controller outputs the frequency ω comp , so that θ g With θ l Matching. Among them, the sine module module is a sin function used to smoothly transition the frequency jump of the microgrid. Angle θ comp From ω comp It is obtained from the grid and used for voltage control in off-grid mode.

[0060] 3) If Figure 4As shown, in grid-connected mode, the PES signal of the main voltage source converter is "1" (ON), while in off-grid mode, it is set to "0" (OFF). The limits of the grid parameters are the same as the IEEE1547 standard.

[0061] 4) In autonomous mode, when the grid constraints are not within their limits, the main voltage regulator performs voltage control, so the PES signal of the main voltage source converter moves towards "0".

[0062] 5) When reconnected to the grid, the PES signal of the main voltage source converter enters state 1, and the frequency, amplitude and phase of the load voltage are consistent with the frequency, amplitude and phase of the grid voltage. The main control mode of the main voltage source converter changes from voltage control to current control.

[0063] Step 600: Based on the working mode of the main voltage source converter, an adaptive current control algorithm is used to control the on and off of each switch in the main voltage source converter according to the maximum power of the main photovoltaic array.

[0064] In the grid interaction mode, the current control is expressed as obtaining the active current component of the load of the main voltage source converter. The control includes the calculation of the in-phase unit template, the weight of the effective part of the load and the reference current of the main voltage source converter.

[0065] Furthermore, if Figure 5 As shown, step 600 includes:

[0066] (61) According to the three-phase grid voltage, a bandpass filter is used to determine the grid voltage amplitude and the main load three-phase voltage.

[0067] Specifically, the detected three-phase grid voltage (v sab ,v sbc )Calculate the phase voltage (v sa ,v sab ,v sbc ), and use a bandpass filter to suppress the harmonics in the phase voltage, and use the following formula to determine the grid voltage amplitude:

[0068]

[0069]

[0070] Among them, V t is the grid voltage amplitude, v sa is the phase a voltage of the three-phase power grid, v sb is the b-phase voltage of the three-phase power grid, v sc is the c-phase voltage of the three-phase power grid, v sab is the voltage between phase a and phase b of the three-phase power grid, v sbcis the voltage between phase b and phase c of the three-phase power grid.

[0071] The following formula is used to determine the three-phase voltage of the main load, that is, the same-phase unit template:

[0072]

[0073] Among them, u pa is the main load a phase voltage, u pb is the main load b phase voltage, u pc It is the main load c phase voltage.

[0074] (62) The Farhang-Ang current control algorithm is used to calculate the active current component of the main load based on the main load induced current, the three-phase voltage of the main load and the gradient adaptive step size.

[0075] The main load induced current includes the main load induced a-phase current, the main load induced b-phase current and the main load induced c-phase current. The main load active current component includes the main load active a-phase current, the main load active b-phase current and the main load active c-phase current.

[0076] Specifically, the Farhang-Ang current control algorithm is used to calculate the phase voltage u of the rth main load a. pa (r), rth a-phase current error λ pa1 (r) and the rth gradient adaptation step size ξ pa1 (r) Calculate the active phase a current I of the r+1th main load pa1 (r+1), where r is a real number representing time. The algorithm can be observed by the noise gradient, that is, by transferring the low-pass filter function T(r) to u pa (r) and λ pa1 (r) is filtered to obtain a more stable step size adaptation. The low-pass filter transfer function T(r) is defined as:

[0077]

[0078] Among them, z is the variable of the low-pass filter transfer function in the discrete domain, and the value range of μ is (0,1).

[0079] According to the rth main load induction a phase current i La1 (r), the rth main load a phase voltage u pa (r) and the active a-phase current of the rth main load I pa1 (r), using the formula λ pa1 (r) = i La1 (r)-(u pa (r)*I pa1 (r)) Calculate the rth a-phase current error λ pa1(r).

[0080] According to the active a-phase current I of the rth main load pa1 (r), the rth gradient adaptive step size ξ pa1 (r), rth a-phase current error λ pa1 (r) and the rth main load a phase voltage u pa (r), using Formula I pa1 (r+1)={I pa1 (r)}+{ξ pa1 (r)*λ pa1 (r)*u pa (r)} Calculate the active phase a current I of the r+1th main load pa1 (r+1).

[0081] Adaptive step size ξ according to the rth gradient pa1 (r), rth a-phase current error λ pa1 (r) and the rth main load a phase voltage u pa (r), using the formula ξ pa1 (r+1)={ξ pa1 (r)}+{η*β pa1 (r)*λ pa1 (r)*u pa (r)} Calculate the r+1th gradient adaptive step size ξ pa1 (r+1).

[0082] Among them, η is a positive constant, which is used for convergence control, and it also minimizes the error. The larger the value of η, the faster the convergence speed and the smaller the error, but the larger the oscillation. When η is in the limit [10 -4 …10 -2 ] changes, the performance of the algorithm is less affected, β pa1 (r) is the estimate of the rth gradient vector.

[0083]

[0084] The input dependent variable coefficient {1-ξpa1(r)*upa(r) 2} is replaced by the coefficient μ, then:

[0085] β pa1 (r) = μ*β pa1 (r-1)+u pa (r)*λ pa1 (r).

[0086] The same method is used to calculate the main load active b-phase current I pb1 and the main load active c-phase current I pc1 .

[0087] (63) When the working mode of the main voltage source converter is the grid-connected mode, the main voltage source converter reference current is calculated according to the grid voltage amplitude, the main load three-phase voltage, the main load active current component and the main photovoltaic array maximum power. The main voltage source converter current error is calculated according to the main voltage source converter reference current and the induced current of the main voltage source converter.

[0088] The main voltage source converter reference current includes a main voltage source converter phase a reference current, a main voltage source converter phase b reference current and a main voltage source converter phase c reference current.

[0089] Specifically, the formula Calculate the average active current of the main load; where I pLavg1 is the average active current of the main load, I pa1 is the active phase a current of the main load, I pb1 is the active phase b current of the main load, I pc1 It is the active c-phase current of the main load.

[0090] According to the maximum power of the main photovoltaic array and the voltage amplitude of the grid, the formula is used Calculate the feedforward term of the maximum power of the main photovoltaic array; where I wpv1 is the feedforward term for the maximum power of the main PV array, P pv1 is the maximum power of the main photovoltaic array, V t is the grid voltage amplitude. The test dynamic performance is improved by the feed-forward term of the maximum power of the main photovoltaic array.

[0091] According to the average active current of the main load and the feedforward term of the maximum power of the main photovoltaic array, the formula I is used. pnet1 =I pLavg1 -I wpv1 Calculate the main reference grid current amplitude; where I pnet1 Main reference grid current amplitude.

[0092] According to the main reference grid current amplitude and the main load three-phase voltage, the formula is used Calculate the main voltage source converter reference current; where, is the reference current of phase a of the main voltage source converter, is the reference current of phase b of the main voltage source converter, is the reference current of phase c of the main voltage source converter, u pa is the main load a phase voltage, u pb is the main load b phase voltage, u pc It is the main load c phase voltage.

[0093] The inductive current (isa1 、i sb1 、i sc1 ) and the main voltage source converter reference current ( and ) is compared with the output current. The resulting error is fed to the hysteresis controller in the current control to generate the switching pulses.

[0094] (64) When the working mode of the main voltage source converter is the off-grid mode, a main load induced voltage error is determined according to the main load induced voltage reference voltage and the main load induced voltage. According to the main load induced voltage error, a main load reference current is determined by using a non-ideal ratio reset controller. According to the main load reference current, the main load active current component and the main load three-phase voltage, a main voltage source converter current error is determined.

[0095] Specifically, the main load active induced current is calculated according to the main load active current component and the main load three-phase voltage. The main voltage source converter current error is determined according to the main load reference current and the main load active induced current. The main voltage source converter current error includes the main voltage source converter a phase current error i eLa , the main voltage source converter b phase current error i eLb , the main voltage source converter c phase current error i eLc .

[0096] The main load induction reference voltage includes the main load induction a phase reference voltage Main load induction b-phase reference voltage and the main load induction c-phase reference voltage Among them, V p is the maximum amplitude of the reference load frequency, ω r is the maximum amplitude of the reference load voltage, and t represents the time.

[0097] The main load induced voltage includes the main load induced a phase voltage v La1 , the main load induced b phase voltage v Lb1 And the main load induced c-phase voltage v Lc1 , the main load induction voltage error includes the main load induction a phase voltage error v Lae , the main load induced b phase voltage error v Lbe And the main load induced c phase voltage error v Lce :

[0098]

[0099] The main load reference current includes the main load a phase reference current Main load b phase reference current And the main load c phase reference current The main load sense voltage error is provided to the non-ideal ratio reset controller to generate the main load reference current The non-ideal ratio reset controller can reduce the steady-state error between the AC quantities. a (s), T b (s) and T c (s) are the a-phase transfer function, b-phase transfer function and c-phase transfer function of the non-ideal proportional reset controller respectively:

[0100]

[0101]

[0102]

[0103] Modify the above transfer function to:

[0104]

[0105]

[0106]

[0107] k pae =k pbe =k pce =k pv ,k iae =k ibe =k ice =k iv ;

[0108] Among them, s represents the name of the variable in the frequency domain, ω c is the lowest breakpoint frequency of the transfer function, k pv and k iv Reset the proportional gain and integral gain of the controller for non-ideal ratios, respectively.

[0109] The main load active induction current includes the main load active induction a phase current i fa , the main load active induction b phase current i fb and the main load active induction c-phase current i fc The main load active inductive current (i fa 、i fb 、i fc ) through the main load active current component (I pa1 ,I pb1 ,I pc1 ) and the main load three-phase voltage (u pa 、u pb 、upc ) are multiplied together to get

[0110] Main load reference current The active inductive current of the main load (i fa 、i fb 、i fc ) to obtain the main voltage source converter current error (i eLa 、i eLb 、i eLc ):

[0111]

[0112]

[0113]

[0114] The main voltage source converter current error (i eLa 、i eLb 、i eLc ) is fed back to the hysteretic controller to form the switching pulses of the main voltage source converter in off-grid mode.

[0115] (65) Based on the current error of the main voltage source converter, a hysteresis controller is used to control the on and off of each switch in the main voltage source converter.

[0116] Step 700: adopting an adaptive current control method to control the on and off of each switch in the auxiliary voltage source converter according to the auxiliary photovoltaic array maximum power and the auxiliary DC link reference voltage.

[0117] Furthermore, if Figure 6 As shown, step 700 includes:

[0118] (71) Calculate the common coupling voltage amplitude and the auxiliary load three-phase voltage according to the auxiliary load induced voltage. The auxiliary load induced voltage includes the auxiliary load induced a-phase voltage, the auxiliary load induced b-phase voltage and the auxiliary load induced c-phase voltage.

[0119] Specifically, the common coupling voltage amplitude is calculated using the following formula:

[0120]

[0121] Use the following formula to calculate the three-phase voltage of the auxiliary load:

[0122]

[0123] Among them, V t1 is the common coupling voltage amplitude, v La2 The phase a voltage induced by the auxiliary load, v Lb2 is the auxiliary load induced b-phase voltage, vLc2 is the auxiliary load induced c-phase voltage, u pa1 is the phase voltage of auxiliary load a, u pb1 is the auxiliary load b phase voltage, u pc1 is the auxiliary load c-phase voltage.

[0124] It should be noted that the auxiliary load inductive voltage (v La2 、v Lb2 、v Lc2 ) and the main load inductive voltage (v La1 、v Lb1 、v Lc1 )equal.

[0125] (72) The Farhang-Ang current control algorithm is used to calculate the auxiliary load active current component (I pa2 ,I pb2 ,I pc2 ).

[0126] (73) Determine the DC loss using a PI controller based on the auxiliary DC link reference voltage and the induced DC link voltage of the auxiliary voltage source converter.

[0127] Specifically, the auxiliary DC link reference voltage The inductive DC link voltage V dc2 By comparison, the auxiliary DC link voltage error V dce2 (r): Auxiliary DC link voltage error V dce2 (r) is used as the input of the PI controller to obtain the DC loss: I l (r+1)=I l (r)+k pdc V dce2 (r+1)+k idc {V dce2 (r+1)-V dce2 (r)}; where I l (r+1) is the r+1th DC loss, I l (r) is the rth DC loss, k pdc and k idc are the proportional gain and integral gain of the PI controller.

[0128] (74) Calculate the auxiliary voltage source converter reference current based on the common coupling voltage amplitude, the auxiliary load three-phase voltage, the auxiliary load active current component, the DC loss and the auxiliary photovoltaic array maximum power.

[0129] Specifically, the formula Calculate the average value of auxiliary load active current I pLavg2 Among them, I pa2 is the auxiliary load active a-phase current, I pb2 is the auxiliary load active b-phase current, I pc2 is the auxiliary load active c-phase current.

[0130] Using formula Calculate the feed-forward part of the auxiliary photovoltaic array maximum power I wpv2 And the auxiliary reference grid current amplitude I pnet2 .

[0131] Using formula Calculate the auxiliary voltage source converter reference current. Among them, is the reference current of phase a of the auxiliary voltage source converter, is the reference current of phase b of the auxiliary voltage source converter, is the reference current of phase c of the auxiliary voltage source converter, u pa1 is the phase voltage of auxiliary load a, u pb1 is the auxiliary load b phase voltage, u pc1 is the auxiliary load c-phase voltage.

[0132] (75) Calculating an auxiliary voltage source converter current error based on the auxiliary voltage source converter reference current and the auxiliary voltage source converter induced current.

[0133] (76) Based on the current error of the auxiliary voltage source converter, a hysteresis controller is used to control the on and off of each switch in the auxiliary voltage source converter.

[0134] Specifically, the inductive current (i sa2 、i sb2 、i sc2 ) and the auxiliary voltage source converter reference current By comparison, the current error of the auxiliary voltage source converter is obtained and provided to the hysteresis controller in the current control to generate switching pulses.

[0135] Step 800: using a conductance maximum power point tracking algorithm and a PI controller to control the on and off of each switch in the bidirectional converter according to the main DC link reference voltage.

[0136] Figure 7 The process of DC link voltage control of the main voltage regulator and battery current regulation through the bidirectional converter is shown. When the energy storage battery is in the charging state, the converter switch S 7 Working in buck mode, the switch S 8 The positive and negative battery currents correspond to the discharge and charge processes respectively.

[0137] Further, step 800 includes:

[0138] (81) Determine a main DC link error based on the main DC link reference voltage and the sensed DC link voltage of the main voltage source converter. dc1 Subtract the main DC link reference voltage from Then, the main DC link error V is obtained. dce1 (r):

[0139]

[0140] (82) According to the main DC link error, a PI controller PI is used a Determine the energy storage reference current: Among them, k pdc and k idc PI controller a The proportional gain and integral gain, is the r+1th energy storage reference current, is the rth energy storage reference current.

[0141] (83) According to the energy storage reference current and the induced current I of the energy storage battery in the bidirectional converter bat , determine the battery current error I ebat :

[0142] (84) According to the battery current error, a PI controller PI is used b Determine the pulse duty cycle: in, is the duty cycle of the r+1th pulse, is the duty cycle of the rth pulse, k pbat and k ibat PI controller b The proportional gain and integral gain.

[0143] (85) A pulse width modulator is used to control the on and off of each switch in the bidirectional converter according to the pulse duty ratio. The pulse duty ratio is provided to the pulse width modulator so as to 7 and the eighth switch S 8 Generates switching pulses.

[0144] The RT1000 digital real-time simulator is a device that can run power system simulations at real-time speeds. It is a key tool in the power system field for research, development, testing and verification of various power system components and control strategies. Figure 3As shown. The RT1000 digital real-time simulation device includes an RT1000 workstation 10 and an RT1000 model operation unit 11. The RT1000 workstation 10 is connected to the RT1000 model operation unit 11 via Ethernet. During the simulation process, the RT1000 digital real-time simulation device displays simulation results, system status and data through a graphical interface or visualization tool 12, so that users can better understand, analyze and evaluate the behavior of the simulation model.

[0145] like Figure 8 As shown, the real-time simulation operation and analysis steps are described in detail below:

[0146] 1) Model import: Import the constructed PV-storage power station simulation model into the RT1000 digital real-time simulation device.

[0147] 2) Parameter setting: Set relevant initialization parameters and import operation data (including load operation data, photovoltaic and energy storage operation data, and light data).

[0148] 3) Simulation operation and analysis: In the grid-connected mode, when the PV array peak power transitions to no PV power generation, the visualization tool is used to observe the sa2 、i La2 、i vsca2 、V dc2 , v Lab ,I pv2 、v sab , P pv1 , P pv2 、i sa ,I wpv1 ,I pv1 、V dc1 、i sa1 、i La1 、i vsca1 and I wpv2 The waveform changes are used to verify the effectiveness of the MPPT control strategy; the performance of the system during the transition from grid-connected mode to off-grid mode and from off-grid mode to grid-connected mode is observed, and the visualization tool v sa 、v La1 、v La2 、i sa1 and s, i sa1 、i La1 、i vsca1 、V dc1 ,θ g ,θ l ,I bat 、i La1 、i sa2 、i La2 、i vsca2 and V dc2The waveform changes of i are used to verify the effectiveness of the current control strategy of the main voltage source converter control, bidirectional converter control and auxiliary voltage source converter. La2 The auxiliary load senses the a-phase current, i vsca1 The main VSC outputs a-phase current, i vsca2 The auxiliary VSC outputs a-phase current, v Lab is the main VSC filter line voltage, v sab is the grid line voltage, I pv1 The MPPT controller input current of the main VSC, I pv2 Input current to the MPPT controller of the auxiliary VSC.

[0149] 4) Optimization and improvement: Based on the results of performance evaluation, optimize the parameters or control logic of the control strategy to improve performance.

[0150] In summary, compared with the prior art, the beneficial effects of the present invention are:

[0151] 1) An adaptive current control algorithm based on the Farhang-Ang algorithm is adopted. This algorithm has the advantages of simple implementation, low complexity, and adaptive step size. It can observe the good performance of the photovoltaic array in both steady and dynamic states, and improve the robustness of the photovoltaic power station.

[0152] 2) Two photovoltaic arrays with independent incremental conductance maximum power point tracking algorithms are used in the photovoltaic power station, connected to the DC links of the main voltage source converter and the auxiliary voltage source converter in a single-stage configuration.

[0153] 3) The feedforward component of the photovoltaic array power is utilized in the current control algorithm of each voltage source converter in the photovoltaic power station, which improves the dynamic performance of the system and avoids the necessity of a proportional-integral regulator.

[0154] 4) In off-grid mode, the photovoltaic power station improves the voltage distribution at the common coupling point through load current filtering based on the Farhang-Ang control algorithm. The non-ideal proportional reset controller has limited gain at the fundamental frequency and is used for voltage control, providing better control for the comparison of sinusoidal signals.

[0155] 5) Digital real-time simulation is used to simulate the operation of the entire multi-solar photovoltaic array microgrid system, helping to optimize the design and control strategy of the microgrid system and ensure its reliability and efficiency under different situations.

[0156] 6) Compared with traditional controllers, the biggest feature of RT1000 digital real-time simulation is the separation of software and hardware. The specific power grid simulation model runs in the hardware equipment of the RT1000 digital real-time simulation system, and the RT1000 digital real-time simulation software runs in the host computer as a soft controller to control the operation status of the entire power grid. The model can be easily imported, activated and run in the user interface, and the simulation data can be paused at any time to observe.

[0157] 7) RT1000 digital real-time simulation provides a variety of hardware platforms, communication interfaces and protocols, data acquisition and output interfaces to ensure data transmission and sharing between systems, and to ensure the real-time and accuracy of data.

[0158] 8) The digital simulation platform provides an intuitive and friendly graphical user interface and interactive simulation environment, supports real-time data visualization and control, and can help users intuitively observe and analyze simulation results, thereby improving simulation efficiency and accuracy.

[0159] Embodiment 2

[0160] In order to execute the method corresponding to the above-mentioned embodiment 1 to achieve the corresponding functions and technical effects, a digital real-time simulation test system for the control strategy of a photovoltaic power station with energy storage is provided below.

[0161] The digital real-time simulation test system for the control strategy of a photovoltaic power station provided in this embodiment includes: a model building module and an RT1000 digital real-time simulation device.

[0162] The model building module is used to obtain the operation data of the photovoltaic power station and establish a simulation model of the photovoltaic power station; the simulation model of the photovoltaic power station includes a main photovoltaic array 1, an auxiliary photovoltaic array 2, a main voltage source converter 3, an auxiliary voltage source converter 4, a main load 6, an auxiliary load 7, a bidirectional converter 5, a common coupling switch 8 and a three-phase power grid 9; the main photovoltaic array 1, the bidirectional converter 5, the main voltage source converter 3, the main load 6, the common coupling switch 8, and the three-phase power grid 9 are connected in sequence; the auxiliary photovoltaic array 2, the auxiliary voltage source converter 4, the auxiliary load 7, the common coupling switch 8, and the three-phase power grid 9 are connected in sequence.

[0163] The RT1000 digital real-time simulation device is used to simulate the operation process of the photovoltaic power station based on the operation data of the photovoltaic power station, and in the simulation process, according to the output voltage and output current of the main photovoltaic array, the incremental conductance maximum power point tracking algorithm is used to determine the maximum power of the main photovoltaic array and the main DC link reference voltage, and according to the output voltage and output current of the auxiliary photovoltaic array, the incremental conductance maximum power point tracking algorithm is used to determine the maximum power of the auxiliary photovoltaic array and the auxiliary DC link reference voltage; according to the grid voltage angle, grid frequency and main load induced voltage, the working mode of the main voltage source converter is controlled; the working mode is a grid-connected mode or an off-grid mode; based on the working mode of the main voltage source converter, an adaptive current control algorithm is used to control the on-off of each switch in the main voltage source converter according to the maximum power of the main photovoltaic array; an adaptive current control method is used to control the on-off of each switch in the auxiliary voltage source converter according to the maximum power of the auxiliary photovoltaic array and the auxiliary DC link reference voltage; a conductance maximum power point tracking algorithm and a PI controller are used to control the on-off of each switch in the bidirectional converter according to the main DC link reference voltage.

[0164] Compared with the prior art, the digital real-time simulation test system for the control strategy of a photovoltaic power station with energy storage provided in this embodiment has the same beneficial effects as the digital real-time simulation test method for the control strategy of a photovoltaic power station with energy storage provided in Example 1, which will not be repeated here.

[0165] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0166] The principles and implementation methods of the present invention are described in this article using specific examples. The description of the above embodiments is only used to help understand the method and core idea of ​​the present invention. At the same time, for those skilled in the art, according to the idea of ​​the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. A digital real-time simulation test method for a photovoltaic power station control strategy, characterized in that: The digital real-time simulation test method for the control strategy of the photovoltaic power station includes: Obtaining the operation data of the photovoltaic power station; Establishing a photovoltaic power station simulation model; the photovoltaic power station simulation model includes a main photovoltaic array, an auxiliary photovoltaic array, a main voltage source converter, an auxiliary voltage source converter, a main load, an auxiliary load, a bidirectional converter, a common coupling switch and a three-phase power grid; the main photovoltaic array, the bidirectional converter, the main voltage source converter, the main load, the common coupling switch and the three-phase power grid are connected in sequence; the auxiliary photovoltaic array, the auxiliary voltage source converter, the auxiliary load, the common coupling switch and the three-phase power grid are connected in sequence; The photovoltaic power station simulation model is imported into the RT1000 digital real-time simulation device, and the operation process of the photovoltaic power station is simulated based on the operation data of the photovoltaic power station; During the simulation process, according to the output voltage and output current of the main photovoltaic array, the maximum power of the main photovoltaic array and the main DC link reference voltage are determined by using the incremental conductance maximum power point tracking algorithm; according to the output voltage and output current of the auxiliary photovoltaic array, the maximum power of the auxiliary photovoltaic array and the auxiliary DC link reference voltage are determined by using the incremental conductance maximum power point tracking algorithm; Controlling the working mode of the main voltage source converter according to the grid voltage angle, grid frequency and main load induced voltage; the working mode is a grid-connected mode or an off-grid mode; Based on the working mode of the main voltage source converter, an adaptive current control algorithm is adopted to control the on and off of each switch in the main voltage source converter according to the maximum power of the main photovoltaic array; Adopting an adaptive current control method to control the on and off of each switch in the auxiliary voltage source converter according to the maximum power of the auxiliary photovoltaic array and the auxiliary DC link reference voltage; A conductance maximum power point tracking algorithm and a PI controller are used to control the on and off of each switch in the bidirectional converter according to the main DC link reference voltage.

2. The digital real-time simulation test of the control strategy of the photovoltaic power station according to claim 1 is characterized in that: According to the grid voltage angle, grid frequency and main load inductive voltage, the working mode of the main voltage source converter is controlled, specifically including: Determine the voltage angle of the common coupling point according to the induced voltage of the main load; A PI controller is used to control the working mode of the main voltage source converter according to the common coupling point voltage angle, the grid voltage angle and the grid frequency.

3. The digital real-time simulation test of the control strategy of the photovoltaic power station according to claim 1 is characterized in that: Based on the working mode of the main voltage source converter, an adaptive current control algorithm is adopted to control the on and off of each switch in the main voltage source converter according to the maximum power of the main photovoltaic array, specifically including: According to the three-phase grid voltage, a bandpass filter is used to determine the grid voltage amplitude and the three-phase voltage of the main load; The Farhang-Ang current control algorithm is used to calculate the active current component of the main load according to the main load inductive current, the three-phase voltage of the main load and the gradient adaptive step size; When the working mode of the main voltage source converter is the grid-connected mode, the reference current of the main voltage source converter is calculated according to the grid voltage amplitude, the three-phase voltage of the main load, the active current component of the main load and the maximum power of the main photovoltaic array; the current error of the main voltage source converter is calculated according to the reference current of the main voltage source converter and the induced current of the main voltage source converter; When the working mode of the main voltage source converter is the off-grid mode, a main load inductive voltage error is determined according to a main load inductive reference voltage and a main load inductive voltage; a main load reference current is determined according to the main load inductive voltage error by using a non-ideal ratio reset controller; a main voltage source converter current error is determined according to the main load reference current, the main load active current component and the main load three-phase voltage; According to the current error of the main voltage source converter, a hysteresis controller is used to control the on and off of each switch in the main voltage source converter.

4. The digital real-time simulation test of the control strategy of the photovoltaic power station according to claim 3 is characterized in that: The grid voltage amplitude is determined using the following formula: Among them, V t is the grid voltage amplitude, v sa is the phase a voltage of the three-phase power grid, v sb is the b-phase voltage of the three-phase power grid, v sc is the c-phase voltage of the three-phase power grid, v sab is the voltage between phase a and phase b of the three-phase power grid, v sbc is the voltage between phase b and phase c of the three-phase power grid; Use the following formula to determine the main load three-phase voltage: Among them, u pa is the main load a phase voltage, u pb is the main load b phase voltage, u pc It is the main load c phase voltage.

5. The digital real-time simulation test of the control strategy of the photovoltaic power station according to claim 3 is characterized in that: The main load active current component includes the main load active a-phase current, the main load active b-phase current and the main load active c-phase current; The main voltage source converter reference current includes a main voltage source converter a phase reference current, a main voltage source converter b phase reference current and a main voltage source converter c phase reference current; Calculating the reference current of the main voltage source converter according to the grid voltage amplitude, the main load three-phase voltage, the main load active current component and the main photovoltaic array maximum power, specifically includes: Using formula Calculate the average active current of the main load; where I pLavg1 is the average active current of the main load, I pa1 is the active phase a current of the main load, I pb1 is the active phase b current of the main load, I pc1 is the main load active c-phase current; According to the maximum power of the main photovoltaic array and the voltage amplitude of the grid, the formula is used Calculate the feedforward term of the maximum power of the main photovoltaic array; where I wpv1 is the feedforward term for the maximum power of the main PV array, P pv1 is the maximum power of the main photovoltaic array, V t is the grid voltage amplitude; According to the average active current of the main load and the feedforward term of the maximum power of the main photovoltaic array, the formula I is used. pnet1 =I pLavg1 -I wpv1 Calculate the main reference grid current amplitude; where I pnet1 is the main reference grid current amplitude; According to the main reference grid current amplitude and the main load three-phase voltage, the formula is used Calculate the main voltage source converter reference current; where, is the reference current of phase a of the main voltage source converter, is the reference current of phase b of the main voltage source converter, is the reference current of phase c of the main voltage source converter, u pa is the main load a phase voltage, u pb is the main load b phase voltage, u pc It is the main load c phase voltage.

6. The digital real-time simulation test of the control strategy of the photovoltaic power station according to claim 3 is characterized in that: Determining a main voltage source converter current error according to the main load reference current, the main load active current component and the main load three-phase voltage specifically includes: Calculating the main load active inductive current according to the main load active current component and the main load three-phase voltage; A main voltage source converter current error is determined based on the main load reference current and the main load active inductive current.

7. The digital real-time simulation test of the control strategy of the photovoltaic power station according to claim 1 is characterized in that: Adopting an adaptive current control method, according to the auxiliary photovoltaic array maximum power and the auxiliary DC link reference voltage, controlling the on and off of each switch in the auxiliary voltage source converter, specifically includes: Calculate the common coupling voltage amplitude and the auxiliary load three-phase voltage according to the auxiliary load induced voltage; The Farhang-Ang current control algorithm is used to calculate the auxiliary load active current component according to the auxiliary load induced current, the auxiliary load three-phase voltage and gradient adaptive compensation; Determining DC losses using a PI controller based on the auxiliary DC link reference voltage and the induced DC link voltage of the auxiliary voltage source converter; Calculating an auxiliary voltage source converter reference current according to the common coupling voltage amplitude, the auxiliary load three-phase voltage, the auxiliary load active current component, the DC loss and the auxiliary photovoltaic array maximum power; Calculating an auxiliary voltage source converter current error according to the auxiliary voltage source converter reference current and the induced current of the auxiliary voltage source converter; According to the current error of the auxiliary voltage source converter, a hysteresis controller is used to control the on and off of each switch in the auxiliary voltage source converter.

8. The digital real-time simulation test of the control strategy of the photovoltaic power station according to claim 7 is characterized in that: The auxiliary load induced voltage includes an auxiliary load induced a-phase voltage, an auxiliary load induced b-phase voltage and an auxiliary load induced c-phase voltage; The common coupling voltage amplitude is calculated using the following formula: Use the following formula to calculate the three-phase voltage of the auxiliary load: Among them, V t1 is the common coupling voltage amplitude, v La2 The phase a voltage induced by the auxiliary load, v Lb2 is the auxiliary load induced b-phase voltage, v Lc2 is the auxiliary load induced c-phase voltage, u pa1 is the phase voltage of auxiliary load a, u pb1 is the auxiliary load b phase voltage, u pc1 is the auxiliary load c-phase voltage.

9. The digital real-time simulation test of the control strategy of the photovoltaic power station according to claim 1 is characterized in that: Using a conductance maximum power point tracking algorithm and a PI controller, the on and off of each switch in the bidirectional converter is controlled according to the main DC link reference voltage, specifically including: determining a main DC link error based on the main DC link reference voltage and a sensed DC link voltage of the main voltage source converter; According to the main DC link error, a PI controller is used to determine the energy storage reference current; Determining a battery current error according to the energy storage reference current and an induced current of an energy storage battery in the bidirectional converter; According to the battery current error, a pulse duty cycle is determined using a PI controller; A pulse width modulator is used to control the on and off of each switch in the bidirectional converter according to the pulse duty cycle.

10. A digital real-time simulation test system for a photovoltaic power station control strategy, applied to the digital real-time simulation test method for a photovoltaic power station control strategy according to any one of claims 1 to 9, characterized in that: The digital real-time simulation test system for the control strategy of the photovoltaic power station includes: a model building module and an RT1000 digital real-time simulation device; The model building module is used to obtain the operation data of the photovoltaic power station and establish a simulation model of the photovoltaic power station; the simulation model of the photovoltaic power station includes a main photovoltaic array, an auxiliary photovoltaic array, a main voltage source converter, an auxiliary voltage source converter, a main load, an auxiliary load, a bidirectional converter, a common coupling switch and a three-phase power grid; the main photovoltaic array, the bidirectional converter, the main voltage source converter, the main load, the common coupling switch, and the three-phase power grid are connected in sequence; the auxiliary photovoltaic array, the auxiliary voltage source converter, the auxiliary load, the common coupling switch, and the three-phase power grid are connected in sequence; The RT1000 digital real-time simulation device is used to simulate the operation process of the photovoltaic power station based on the operation data of the photovoltaic power station, and in the simulation process, according to the output voltage and output current of the main photovoltaic array, the incremental conductance maximum power point tracking algorithm is used to determine the maximum power of the main photovoltaic array and the main DC link reference voltage, and according to the output voltage and output current of the auxiliary photovoltaic array, the incremental conductance maximum power point tracking algorithm is used to determine the maximum power of the auxiliary photovoltaic array and the auxiliary DC link reference voltage; according to the grid voltage angle, grid frequency and main load induced voltage, the working mode of the main voltage source converter is controlled; the working mode is a grid-connected mode or an off-grid mode; based on the working mode of the main voltage source converter, an adaptive current control algorithm is used to control the on-off of each switch in the main voltage source converter according to the maximum power of the main photovoltaic array; an adaptive current control method is used to control the on-off of each switch in the auxiliary voltage source converter according to the maximum power of the auxiliary photovoltaic array and the auxiliary DC link reference voltage; a conductance maximum power point tracking algorithm and a PI controller are used to control the on-off of each switch in the bidirectional converter according to the main DC link reference voltage.

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