Energy storage converter control method and apparatus

Abstract

The application provides an energy storage converter control method, comprising the following steps: detecting the DC side voltage u dc and the grid angular frequency ω of a three-phase AC power grid between two DC side ports a , b , c ; performing Clarke and Park transformation on the three-phase current i a , b , c ; calculating reference current and current tracking error e1, e2 in a two-phase rotating coordinate system according to given reference active power P ref and reactive power Q ref , combined with the current i d , q and voltage u d , q ; obtaining control voltage according to an expression of an S sliding mode controller with a saturation function introduced, and generating control signals of a control switch device array based on space vector pulse width modulation after Park inverse transformation to control the conduction or turn-off of corresponding switch devices. The application also provides a corresponding energy storage converter control device. The application can improve the adaptability of energy storage converter control, reduce system chattering, and improve control robustness.

Description

Technical Field

[0001] This application relates to the technical field of converter automation control, and in particular to a control method and device for an energy storage converter. Background Technology

[0002] With the rise and widespread application of distributed new energy sources such as wind power and photovoltaics, energy storage converters have seen rapid development in recent years as an effective intermediary for balancing AC and DC power supply equipment in order to reduce the impact of DC power generated by distributed new energy sources on the grid load. By combining the characteristics of converters and energy storage devices, energy storage converters have become an important connection point for DC power supply equipment, electrical equipment, and the grid. They are characterized by multiple inputs and multiple outputs, strong coupling, and nonlinearity. Existing control algorithms for energy storage converters include traditional control algorithms such as PI control; however, existing automatic control methods may have the following drawbacks due to factors such as fixed parameters:

[0003] On the one hand, since the parameters of traditional PI controllers are fixed, it means that the controller is too sensitive to system parameters during operation. If the system parameters change or there is a mismatch, it may not be able to make effective adjustments, resulting in poor adaptability and problems such as poor dynamic response and severe waveform distortion.

[0004] On the other hand, when using the traditional exponential reaching law of adaptive controllers for sliding mode control, problems may arise such as slow reaching speed and poor dynamic response when the parameters are not properly selected, or fast reaching speed and severe chattering.

[0005] Therefore, improving the adaptability of control, reducing system chattering, and enhancing control robustness are technical problems that need to be solved in order to address issues such as poor dynamic response and severe waveform distortion in energy storage converter control. Summary of the Invention

[0006] In view of the above-mentioned problems of the prior art, this application provides a control method for energy storage converter, which can improve the adaptability of control, reduce system chattering, and enhance control robustness.

[0007] To achieve the above objectives, the first aspect of this application provides a control method for an energy storage converter, comprising:

[0008] A control method for an energy storage converter, characterized in that the energy storage converter includes three grid-side ports and two DC-side ports; each grid-side port is connected to each DC-side port by a switching device, forming a switching device array; the three grid-side ports are connected to the three phases of a three-phase AC grid, using a three-phase symmetrical connection without a neutral wire; the two DC-side ports are connected to the positive and negative terminals of the energy storage medium, and are composed of a DC bus capacitor connected in parallel with a battery;

[0009] The method includes:

[0010] The DC-side voltage u between the two DC-side ports was detected. dc The grid angular frequency ω and the three-phase current i are obtained by detecting the three phases of the three-phase AC grid through the PLL module. a i b i c ;

[0011] The three-phase current i a i b i c The Clarke transform is used to obtain the current i in the two-phase stationary coordinate system. α i β ;

[0012] The current i in the two-phase stationary coordinate system ɑ i β Combining the grid angular frequency ω, the Park transformation is used to obtain the current i in the two-phase rotating coordinate system. d i q and voltage u d ,u q ;

[0013] Given the reference active power P ref and reactive power Q ref Combined with the voltage u d u q Calculate the reference current in the two-phase rotating coordinate system

[0014] According to the current i in the two-phase rotating coordinate system d i q and reference current Calculate the current tracking errors e1 and e2 in the two-phase rotating coordinate system;

[0015] Based on sliding mode control theory, the following sliding mode controller expression in a two-phase rotating coordinate system is obtained by using an exponential reaching law S that incorporates a saturation function; based on the sliding mode controller expression, the control voltage is obtained.

[0016]

[0017] Among them, S d S q These are the switching control functions for the d-axis and q-axis, respectively; L is the grid-side inductance, R is the grid-side resistance; c1 and c2 are the integral gain coefficients.

[0018] The control voltage Using the aforementioned grid angular frequency ω, the voltage u in the two-phase stationary coordinate system is obtained by inverse Park transformation. α u β ;

[0019] The voltage u in the two-phase stationary coordinate system α u β Based on space vector pulse width modulation, control signals are generated to control the switching device array to control the corresponding switching devices to turn on or off.

[0020] As described above, by using the sliding mode control theory and the dual-loop control structure to control the switching device array of the energy storage converter according to the change of current tracking error, the dynamic response of the energy storage converter to the grid load can be improved; by using the exponential reaching law that introduces the saturation function, system chattering during the control process can be reduced; by using space vector pulse width modulation technology, the maximum utilization rate of DC voltage can be improved, switching losses can be reduced, output waveform quality can be improved, dynamic response and stability can be enhanced, and it is easy to implement.

[0021] As one possible implementation of the first aspect, the exponential reaching law S of the saturation function sat() is introduced as follows:

[0022]

[0023] Where s is the system sliding surface; k > 0 is the sliding gain coefficient; ε > 0 is the boundary layer thickness coefficient; η and l are control parameters; and sat(s) is the linear saturation function.

[0024] Therefore, by using the improved exponential approach law to reduce chattering when the system state trajectory approaches the sliding surface, the robustness and dynamic response speed of the control system are improved.

[0025] As one possible implementation of the first aspect, the system sliding surface introduces an integral term to eliminate errors, calculated according to the following formula:

[0026]

[0027] Wherein, s1 and s2 are the sliding surfaces of the d-axis and q-axis in the two-phase rotating coordinate system dq, respectively.

[0028] As shown above, by introducing an integral term into the sliding surface, steady-state error can be eliminated, the system's resistance to parameter uncertainties and external disturbances can be improved, and tracking performance and response speed can be increased.

[0029] As one possible implementation of the first aspect, the sliding mode controller is expressed as follows:

[0030]

[0031] Wherein, η1, η2, l1, l2 are calculated according to the sliding surfaces s1 and s2 of the corresponding d-axis and q-axis by the following formula.

[0032]

[0033]

[0034] Where n = 1 or 2; δ and σ are parameters that define the boundary layer, 0 < μ < 1, v > 0; l3 and l4 are positive odd numbers, and l3 > l4.

[0035] Therefore, by using the exponential reaching law of the saturation function, chattering is reduced and the system response speed is improved.

[0036] As one possible implementation of the first aspect, the saturation functions sat(s1) and sat(s2) are calculated by the following formula:

[0037]

[0038] Where Δ is the parameter that defines the boundary layer.

[0039] As shown above, constructing a saturation function using piecewise functions can simplify the calculation process and improve the system response speed; adjusting it through a boundary layer provides good flexibility.

[0040] As one possible implementation of the first aspect, the reference current and the current tracking error are obtained according to the following formula:

[0041]

[0042]

[0043] As mentioned above, tracking changes in active and reactive power can be used to optimize the energy utilization efficiency of grid-connected power generation. Further tracking control through current can directly reflect load characteristics and has a faster response speed.

[0044] As one possible implementation of the first aspect, the control voltage The following formula is used to calculate:

[0045]

[0046] As shown above, voltage control can effectively reduce voltage fluctuations in the system and ensure that the load equipment operates under a stable voltage.

[0047] A second aspect of this application provides an energy storage converter control device, comprising:

[0048] The outer loop calculation module is used to detect the DC-side voltage u between the two DC-side ports. dc The grid angular frequency ω and the three-phase current i are obtained by detecting the three phases of the three-phase AC grid through the PLL module. a i b i c ; the three-phase current i a i b i c The Clarke transform is used to obtain the current i in the two-phase stationary coordinate system. α i β The current i in the two-phase stationary coordinate system α i β Combining the grid angular frequency ω, the Park transformation is used to obtain the current i in the two-phase rotating coordinate system. d i q and voltage u d u q ;

[0049] The inner-loop calculation module is used to calculate the given reference active power P. ref and reactive power Q ref Combined with the voltage u d u q Calculate the reference current in the two-phase rotating coordinate system According to the current i in the two-phase rotating coordinate system d i q and reference current The current tracking errors e1 and e2 in the two-phase rotating coordinate system are calculated. Based on sliding mode control theory, an exponential reaching law S in the two-phase rotating coordinate system with an introduced saturation function is used to obtain the sliding mode controller expression. Based on the sliding mode controller expression, the control voltage is obtained.

[0050] The control drive module is used to transfer the control voltage. Using the aforementioned grid angular frequency ω, the voltage u in the two-phase stationary coordinate system is obtained by inverse Park transformation. α u β The voltage u in the two-phase stationary coordinate system α u β The control signal for the control switching device array is generated based on space vector pulse width modulation to control the conduction or cutoff of the corresponding switching devices.

[0051] A third aspect of this application provides a computing device, including: a processor and a memory storing program instructions thereon, the program instructions, when executed by the processor, causing the processor to perform the energy storage converter control method according to any one of the first aspects.

[0052] A fourth aspect of this application provides a computer-readable storage medium, characterized in that it stores program instructions thereon, which, when executed by a computer, cause the computer to perform the energy storage converter control method according to any one of the first aspects. Attached Figure Description

[0053] Figure 1 This is a flowchart of the first embodiment of the energy storage converter control method of this application;

[0054] Figure 2 This is a flowchart of the second embodiment of the energy storage converter control method of this application;

[0055] Figure 3 This is a topology diagram of the main circuit of the energy storage converter provided in the second embodiment of this application;

[0056] Figure 4 This is a control structure block diagram provided in the second embodiment of this application;

[0057] Figure 5 This is a schematic diagram of the energy storage converter control method device provided in the embodiments of this application;

[0058] Figure 6 This is a schematic structural diagram of a computing device provided in an embodiment of this application.

[0059] It should be understood that the dimensions and shapes of the blocks in the above structural diagrams are for reference only and should not constitute an exclusive interpretation of the embodiments of the present invention. The relative positions and inclusion relationships between the blocks presented in the structural diagrams are only schematic representations of the structural relationships between the blocks, and are not intended to limit the physical connection methods of the embodiments of the present invention. Detailed Implementation

[0060] The technical solutions provided in this application will be further described below with reference to the accompanying drawings and embodiments. It should be understood that the system architecture and business scenarios provided in the embodiments of this application are mainly for illustrating possible implementations of the technical solutions of this application and should not be construed as the sole limitation on the technical solutions of this application. Those skilled in the art will recognize that the technical solutions provided in this application are equally applicable to similar technical problems as system architectures evolve and new business scenarios emerge.

[0061] It should be understood that the energy storage converter control scheme provided in the embodiments of this application includes an energy storage converter control method, apparatus, and computing device. Since these technical solutions solve problems based on the same or similar principles, some repetitive details may not be repeated in the following descriptions of specific embodiments. However, it should be considered that these specific embodiments have mutual references and can be combined with each other.

[0062] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. In case of any inconsistency, the meaning set forth in this specification or derived from the content described herein shall prevail. Furthermore, the terminology used herein is for the purpose of describing embodiments of this application only and is not intended to limit this application. To accurately describe the technical content of this application and to accurately understand the invention, the following explanations or definitions of the terms used in this specification are provided before describing specific embodiments:

[0063] 1) Sliding Mode Control (SMC): This is a nonlinear control strategy designed to make the system's state trajectory slide on a designed sliding surface, thereby achieving the desired dynamic performance. The core idea of ​​sliding mode control is to design a suitable sliding surface (or sliding mode surface) so that the system state can quickly reach that surface and slide on it, thereby achieving system stability and robustness.

[0064] 2) Adaptive Reaching Law (ARL): This is an important technique in sliding mode control. Compared with the traditional fixed reaching law, the adaptive reaching law can adaptively adjust the reaching speed according to the actual state of the system and external disturbances, thereby reducing chattering and improving the robustness and performance of the system.

[0065] 3) Lyapunov Stability Analysis: This is a mathematical method for studying the stability of dynamic systems. This method analyzes the stability of a system by constructing a scalar function (called a Lyapunov function) without having to solve for the specific solution of the system. Lyapunov stability analysis is widely used in control theory, dynamics, and nonlinear systems.

[0066] The energy storage converter control scheme provided in this application can obtain the power system variables of the outer loop control of the energy storage converter and calculate the key variables of the inner loop controller according to sliding mode control theory to drive the relevant electronic devices of the energy storage converter. This provides an energy storage converter control method that can improve control adaptability, reduce system chattering, and enhance control robustness. This application can be applied to various renewable energy grid connection, microgrids, power grids, industrial and residential energy storage, electric vehicle charging stations, and other fields. The embodiments of this application are described in detail below with reference to the accompanying drawings.

[0067] The first embodiment of this application provides a control method for an energy storage converter. The energy storage converter in the first embodiment includes three grid-side ports and two DC-side ports; each grid-side port is connected to a switching device, forming a switching device array; the three grid-side ports are connected to the three phases of a three-phase AC power grid, using a three-phase symmetrical connection without a neutral wire; the two DC-side ports are connected to the positive and negative terminals of the energy storage medium, and consist of a DC bus capacitor connected in parallel with a battery.

[0068] In some embodiments, the energy storage converter connects a DC power supply, an AC power grid, and an energy storage device; the DC power supply includes DC power generation equipment such as photovoltaic panels and wind turbines, and the AC power grid mainly includes equipment such as the public power grid; the converter of the energy storage converter is mainly composed of semiconductor switching devices such as metal oxide semiconductor field-effect transistors (MOSFETs); it may also include devices such as DC converters, AC filters, communication interfaces, and sensors.

[0069] In some embodiments, the topology of the energy storage converter includes unipolar, bipolar, two-level, and three-level types.

[0070] The following will combine Figure 1 The implementation of each step of the method is described in detail, including steps S10-S80.

[0071] S10: Detect the DC-side voltage u between the two DC-side ports. dc The grid angular frequency ω and the three-phase current i are obtained by detecting the three phases of the three-phase AC grid through the PLL module. a i b i c .

[0072] In some embodiments, the power system variables of the energy storage converter may include voltage, current, frequency, power, power factor, temperature, state of charge, health status, environmental conditions, etc., measured on both the AC and DC sides; wherein, power includes active power and reactive power.

[0073] In some embodiments, the aforementioned power system variables can be obtained through phase-locked loops, frequency-locked loops, voltage and current sensors, frequency meters, power meters, power factor meters, temperature sensors, battery management systems, etc.

[0074] S20: Convert the three-phase current i a i b i c The Clarke transform is used to obtain the current i in the two-phase stationary coordinate system. α i β .

[0075] In some embodiments, the Clarke transform can be used to convert the three-phase current i a i b i c Transformed into current i in a two-phase stationary coordinate system α i β The Park transform can also be used to directly convert the three-phase current i a i b i c Transformed into a two-phase rotating coordinate system for the current i d i q and voltage u d u q Other coordinate transformation techniques can also be used for coordinate transformation.

[0076] S30: The current i in the two-phase stationary coordinate system is... α i β By combining the grid angular frequency ω, the Park transformation is used to obtain the current i in the two-phase rotating coordinate system. d i q and voltage u d u q .

[0077] In some embodiments, the current i in a two-phase rotating coordinate system can be calculated by combining the grid angular frequency ω. d i g and voltage u d u q The current i in the two-phase rotating coordinate system can also be calculated by combining the AC phase angle of the power grid. d i q and voltage u d u q .

[0078] In some embodiments, the grid angular frequency ω can be obtained through a phase-locked loop or a frequency-locked loop.

[0079] S40: Given the reference active power P ref and reactive power Q ref Combined with the voltage u in a two-phase rotating coordinate system d u q Calculate the reference current in the two-phase rotating coordinate system

[0080] In some embodiments, the acquired power system variables can be converted into reference variables for variable tracking in subsequent control processes, such as active power and reactive power being converted into circuit current.

[0081] In some embodiments, outer loop control may include power control, voltage control, frequency control, energy management control, protection control, etc.; for example, power control may include active power and reactive power control, and power reference values ​​may be set according to grid demand or dispatch instructions.

[0082] S50: Based on the current i in the two-phase rotating coordinate system d i q and reference current The current tracking errors e1 and e2 in the two-phase rotating coordinate system are calculated.

[0083] In some embodiments, the key tracking variable of the controller is current, but power, voltage, frequency, etc. may also be used; the tracking variable is the deviation between the reference value and the actual value of the variable obtained according to grid demand or dispatch instructions, etc.; the converter controls the voltage and other parameters of the power system through the tracking variable, such as generating control signals based on the tracking current and adjusting the controller output.

[0084] S60: Based on sliding mode control theory, the expression for the sliding mode controller in a two-phase rotating coordinate system is obtained using an exponential reaching law S that incorporates a saturation function; based on the sliding mode controller expression, the control voltage is obtained.

[0085] In some embodiments, sliding mode control theory designs a system sliding surface so that the system state trajectory can slide on the surface. The sliding surface is defined as a hyperplane s(x) = 0, where x is the system state vector, such as the tracking current in the controller.

[0086] In some embodiments, an integral term may be introduced into the sliding surface to eliminate long-term errors.

[0087] In some embodiments, in order to enable the system state trajectory to reach and remain on the sliding surface, a switching control law needs to be designed; the control law can be selected from conventional control law, exponential reaching law, superspiral reaching law, second-order reaching law, adaptive reaching law, etc.; among them, the exponential reaching law ensures that the system state reaches the switching surface in a finite time by introducing an exponential term.

[0088] In some embodiments, an adaptive reaching law is used to limit the jitter amplitude of the control input by introducing a saturation function, as shown in the following equation:

[0089]

[0090] Where Δ is the parameter defining the boundary layer, and s is the sliding surface.

[0091] In some embodiments, the control rate can be used using the following function:

[0092]

[0093] Where ε>0, k>0 are sliding mode gain coefficients; η, l are control parameters.

[0094] In some embodiments, the controller drives the relevant electronic devices through control expressions. For example, in an energy storage converter using a single-electrode two-level topology, applying an adaptive reaching law that introduces a saturation function, the control expression for its switching devices in a two-phase rotating coordinate system (dq) can be given by the following equation:

[0095]

[0096] Among them, S d S q These are the control functions for the d-axis and q-axis, respectively; L is the grid-side inductance, and R is the grid-side resistance; u dc η1 represents the DC bus voltage; s1 and s2 represent the sliding surfaces of the d-axis and q-axis, respectively; η1, η2, l1, and l2 represent the relevant control parameters.

[0097] S70: The control voltage Using the aforementioned grid angular frequency ω, the voltage u in the two-phase stationary coordinate system is obtained by inverse Park transformation. α u β .

[0098] In some embodiments, the coordinate system after three-phase two-phase transformation can be converted back to the three-phase stationary coordinate system by means of methods such as the Park inverse transformation, so as to further process or output to the actual circuit.

[0099] S80: The voltage u in the two-phase stationary coordinate system α u β Based on space vector pulse width modulation, control signals are generated to control the switching device array to control the corresponding switching devices to turn on or off.

[0100] In some embodiments, the controller provides control pulse signals by tracking key variables to drive relevant electronic devices; wherein, the relevant electronic devices are mainly semiconductor switching devices in the energy storage converter structure, etc.

[0101] In some embodiments, the switching device can be controlled by adjusting the control expression to control voltage, current, power, etc.

[0102] In some embodiments, the control results may be further processed through diagnosis, debugging, etc.

[0103] In some embodiments, the control results can also be used to precisely control the circuit through PID, SPWM, SVPWM, and other methods.

[0104] The second embodiment of this application provides a control method for an energy storage converter with a single-electrode two-level topology. The following will refer to... Figure 2 The flowchart shown illustrates that the method provided in this second embodiment includes the following steps S200-S250.

[0105] The energy storage converter (PCS) used in this embodiment is a unipolar two-level topology, and the main circuit topology diagram is as follows. Figure 3 As shown. The DC side consists of a DC bus capacitor and a lithium-ion battery as the energy storage medium. The AC / DC conversion circuit consists of six switching devices. The AC side adopts a three-phase symmetrical connection without a neutral wire. Where R is the grid-side resistor and L is the grid-side filter inductor. a i b i c e is the grid-side current. a e b e c U is the grid-side voltage, C is the bus capacitance, and u is the voltage on the grid side. dc This is the DC bus voltage.

[0106] S200: Obtain the active and reactive power on the grid side, as well as the actual current and voltage in the energy storage converter circuit.

[0107] Relevant status and parameter values ​​in the power grid and energy storage converter circuits can be obtained through devices such as PLL phase-locked loops.

[0108] S210: Obtain the reference current for control based on the active and reactive power on the grid side.

[0109] Assuming the grid voltage is ideal and three-phase symmetrical, according to Kirchhoff's voltage law, the voltage equation of PCS in the abc three-phase stationary coordinate system is:

[0110]

[0111] During grid-connected operation, the two thyristors on each bridge arm operate in complementary states; therefore, the switching function is defined as follows:

[0112]

[0113] Where k = a, b, c. 1 and 0 represent the upper and lower bridge arms being conductive, respectively. After Clarke and Park transformations, the mathematical model in the two-phase rotating coordinate system dq is obtained as follows:

[0114]

[0115] Where ω is the grid angular frequency, i d i qThe currents along the d-axis and q-axis are respectively, u d u q The voltages on the d-axis and q-axis are S, respectively. d S q These are the switching functions for the d-axis and q-axis, respectively.

[0116] According to instantaneous theory, the active power P and reactive power Q on the grid side are respectively:

[0117]

[0118] Therefore, given a reference active power P ref and reactive power Q ref Therefore, the reference current in the two-phase rotating coordinate system dq is:

[0119]

[0120] in, These are the reference currents for the d-axis and q-axis, respectively; u d u q These are the actual voltages along the d-axis and q-axis, respectively.

[0121] S220: Calculate the current tracking error and the integral sliding surface based on sliding mode control theory.

[0122] According to sliding mode control theory, the current tracking error e is defined as the difference between the reference current and the actual current, that is:

[0123]

[0124] Where e1 and e2 are the current tracking errors of the d-axis and q-axis, respectively, i d i q These are the actual currents along the d-axis and q-axis, respectively.

[0125] To eliminate errors, an integral term is introduced into the sliding surface, namely:

[0126]

[0127] Where s1 and s2 are the integral sliding surfaces of the d-axis and q-axis, respectively; c1 and c2 are the integral gain coefficients.

[0128] S230: Based on sliding mode control theory, obtain the expression for the PCS current inner loop controller.

[0129] Based on the mathematical model of the energy storage converter topology in the two-phase rotating coordinate system dq of the embodiments of this application, the sliding mode controller expression of the PCS current inner loop, or the switching control functions S of the d-axis and q-axis, can be obtained. d S q for:

[0130]

[0131] Among them, i d i q These are the actual currents along the d-axis and q-axis, respectively; u d u q These are the actual voltages along the d-axis and q-axis, respectively.

[0132] Assuming the reference current changes slowly and its approximate derivative is 0, then differentiating with respect to the sliding surface yields:

[0133]

[0134] Then the switching control functions S for the d-axis and q-axis d ,S q It can be written as:

[0135]

[0136] According to sliding mode control theory, the exponential reaching law is set as the derivative of the sliding surface to ensure that the system reaches the switching surface and maintains the sliding mode within a finite time. If the traditional exponential reaching law is used, the controller expression S... d S q It can be written as:

[0137]

[0138] Where ζ>0 and k>0 are sliding mode gain coefficients.

[0139] Analyzing the traditional exponential reaching law, we can find that when the system state is far from the sliding surface, it approaches exponentially; when the system is close to the sliding surface, it approaches at a constant velocity. The expression for the exponential reaching law is as follows:

[0140]

[0141] When the sliding surface s approaches zero, its limit expression is:

[0142]

[0143] Therefore, it can be found that the stability of the exponential reaching law is related to the choice of ζ. When ε is too small, the reaching speed is slow and the dynamic response capability is poor; when ε is too large, the reaching speed is fast, and crossing occurs on the sliding surface, resulting in severe chattering.

[0144] Therefore, this application proposes an improved exponential reaching law. The design of the improved exponential reaching law will be described below. It can be used directly in actual implementation.

[0145] The improved exponential reaching law S proposed in this application is shown in the following formula:

[0146]

[0147] Where η and l are control parameters, and sat(s) is a linear saturation function, obtained from the following equation:

[0148]

[0149]

[0150]

[0151] Where δ, σ, and Δ are parameters defining the boundary layer, 0 < μ < 1, v > 0; l3 and l4 are positive odd numbers, and l3 > l4.

[0152] As can be seen from the above formula, when the system is far away from the sliding surface, the approach speed is faster and the approach time is shorter. When the system is close to the sliding surface, due to the variable exponent term and the introduction of the saturation function, the speed at which the system approaches the sliding surface will decrease, which can effectively alleviate the chattering phenomenon of the traditional exponential approach law.

[0153] The Lyapunov function is selected to perform stability analysis on the improved exponential reaching law proposed in the embodiments of this application:

[0154]

[0155] Differentiating the above formula, we get:

[0156]

[0157] The improved exponential convergence law Substituting, we get:

[0158]

[0159] From the above equation, we can see that since --s·sat(s)<0, -ks l+1 If < 0, then V(s) > 0. Therefore, the sliding mode system gradually stabilizes and reaches the origin within a finite time, satisfying the reachability condition. This reaching law meets the design requirements.

[0160] Therefore, the switching control function S using the improved exponential reaching law is used. d S q It can be written as:

[0161]

[0162] S240: Calculates the control voltage used for control.

[0163] Based on the switching control function S using the improved exponential reaching law d S q The control voltage of the switching device in the dq coordinate system can be obtained by the following formula:

[0164]

[0165] The above control voltage is obtained by inverse Park transformation in two-phase stationary coordinate system u. α u β .

[0166] S250: The control pulse signal of the PCS is obtained through SVPWM to drive the relevant electronic components of the energy storage converter.

[0167] SVPWM based on u α u β The optimal timing of the two basic voltage vectors and the zero vector is determined, and a series of precise PCS control pulse signals are generated by an algorithm. These signals drive the six switching devices of the energy storage converter, determining the on and off times of each device, thereby adjusting the converter's output to ensure it operates according to the predetermined target.

[0168] The control method block diagram of this application embodiment is as follows: Figure 4 As shown.

[0169] The third embodiment of this application provides an energy storage converter control device, which can be used to implement the energy storage converter control method in the above embodiments, such as... Figure 5 As shown, the energy storage converter control device includes:

[0170] The outer loop calculation module is used to detect the DC-side voltage u between the two DC-side ports. dc The grid angular frequency ω and the three-phase current i are obtained by detecting the three phases of the three-phase AC grid through the PLL module. a i b i c ; the three-phase current i a i b i c The Clarke transform is used to obtain the current i in the two-phase stationary coordinate system. α i β The current i in the two-phase stationary coordinate system α i β Combining the grid angular frequency ω, the Park transformation is used to obtain the current i in the two-phase rotating coordinate system. d i q and voltage u d u gSpecifically, the outer ring calculation module can be used to implement steps S10-S30 in the first embodiment and its optional embodiments.

[0171] The inner-loop calculation module is used to calculate the given reference active power P. ref and reactive power Q ref Combined with the voltage u d u q Calculate the reference current in the two-phase rotating coordinate system According to the current i in the two-phase rotating coordinate system d i q and reference current The current tracking errors e1 and e2 in the two-phase rotating coordinate system are calculated. Based on sliding mode control theory, an exponential reaching law S in the two-phase rotating coordinate system with an introduced saturation function is used to obtain the sliding mode controller expression. Based on the sliding mode controller expression, the control voltage is obtained. Specifically, the inner loop calculation module can be used to implement steps S40-S60 in the first embodiment and its optional embodiments.

[0172] The control drive module is used to transfer the control voltage. Using the aforementioned grid angular frequency ω, the voltage u in the two-phase stationary coordinate system is obtained by inverse Park transformation. α u β The voltage u in the two-phase stationary coordinate system α u β The control signal for the control switching device array is generated based on space vector pulse width modulation to control the conduction or cutoff of the corresponding switching devices; specifically, the control drive module can be used to implement steps S70-S80 in the first embodiment and its optional embodiments.

[0173] Figure 6 This is a schematic structural diagram of a computing device 900 provided in an embodiment of this application. This computing device can execute various optional embodiments of the methods described above. The computing device can be a terminal, or a chip or chip system within the terminal. Figure 6 As shown, the computing device 900 includes: a processor 910, a memory 920, and a communication interface 930.

[0174] It should be understood that Figure 6 The communication interface 930 in the computing device 900 shown can be used to communicate with other devices, and may specifically include one or more transceiver circuits or interface circuits.

[0175] The processor 910 can be connected to the memory 920. The memory 920 can be used to store the program code and data. Therefore, the memory 920 can be a storage unit inside the processor 910, an external storage unit independent of the processor 910, or a component that includes both the storage unit inside the processor 910 and the external storage unit independent of the processor 910.

[0176] Optionally, the computing device 900 may also include a bus. The memory 920 and communication interface 930 can be connected to the processor 910 via the bus. The bus can be a Peripheral Component Interconnect (PCI) bus or an Extended Industry Standard Architecture (EISA) bus, etc. The bus can be divided into an address bus, a data bus, a control bus, etc. For ease of representation, Figure 6 The symbol is represented by a line without an arrow, but this does not mean that there is only one bus or one type of bus.

[0177] It should be understood that in the embodiments of this application, the processor 910 may be a central processing unit (CPU). The processor may also be other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The general-purpose processor may be a microprocessor or any conventional processor. Alternatively, the processor 910 may employ one or more integrated circuits to execute relevant programs to implement the technical solutions provided in the embodiments of this application.

[0178] The memory 920 may include read-only memory and random access memory, and provides instructions and data to the processor 910. A portion of the processor 910 may also include non-volatile random access memory. For example, the processor 910 may also store device type information.

[0179] When the computing device 900 is running, the processor 910 executes computer execution instructions stored in the memory 920 to perform any of the operational steps of the above method and any of the optional embodiments thereof.

[0180] It should be understood that the computing device 900 according to the embodiments of this application can correspond to the corresponding subject in executing the methods according to the various embodiments of this application, and the above and other operations and / or functions of each module in the computing device 900 are respectively for implementing the corresponding processes of the methods of this embodiment. For the sake of brevity, they will not be described in detail here.

[0181] Those skilled in the art will recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0182] Those skilled in the art will understand that, for the sake of convenience and brevity, the specific working processes of the systems, devices, and units described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here.

[0183] In the several embodiments provided in this application, it should be understood that the disclosed systems, apparatuses, and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative; for instance, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces; the indirect coupling or communication connection between apparatuses or units may be electrical, mechanical, or other forms.

[0184] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0185] In addition, the functional units in the various embodiments of this application can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit.

[0186] If the aforementioned functions are implemented as software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, or a portion of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of this application. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0187] The computer storage medium in this application embodiment can be any combination of one or more computer-readable media. A computer-readable medium can be a computer-readable signal medium or a computer-readable storage medium. For example, a computer-readable storage medium can be, but is not limited to, an electrical, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any combination thereof. More specific examples of computer-readable storage media (a non-exhaustive list) include: an electrical connection having one or more wires, a portable computer disk, a hard disk, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), optical fiber, portable compact disk read-only memory (CD-ROM), optical storage device, magnetic storage device, or any suitable combination thereof. In this document, a computer-readable storage medium can be any tangible medium containing or storing a program that can be used by or in conjunction with an instruction execution system, apparatus, or device.

[0188] Computer-readable signal media may include data signals propagated in baseband or as part of a carrier wave, carrying computer-readable program code. Such propagated data signals may take various forms, including but not limited to electromagnetic signals, optical signals, or any suitable combination thereof. Computer-readable signal media may also be any computer-readable medium other than computer-readable storage media, capable of sending, propagating, or transmitting programs for use by or in connection with an instruction execution system, apparatus, or device.

[0189] The program code contained on a computer-readable medium may be transmitted using any suitable medium, including, but not limited to, wireless, wire, optical fiber, RF, etc., or any suitable combination thereof.

[0190] Computer program code for performing the operations of this application can be written in one or more programming languages ​​or a combination thereof, including object-oriented programming languages ​​such as Java, Smalltalk, and C++, and conventional procedural programming languages ​​such as "C" or similar programming languages. The program code can be executed entirely on the user's computer, partially on the user's computer, as a standalone software package, partially on the user's computer and partially on a remote computer, or entirely on a remote computer or server. In cases involving remote computers, the remote computer can be connected to the user's computer via any type of network, including a local area network (LAN) or a wide area network (WAN), or it can be connected to an external computer (e.g., via the Internet using an Internet service provider).

[0191] Furthermore, the terms "first, second, third, etc." or similar terms such as module A, module B, and module C used in the specification and claims are only used to distinguish similar objects and do not represent a specific ordering of objects. It is understood that, where permissible, a specific order or sequence may be interchanged so that the embodiments of this application described herein can be implemented in an order other than that illustrated or described herein.

[0192] In the above description, the labels of the steps involved, such as S110, S120, etc., do not mean that the steps will necessarily be executed. The order of the steps can be interchanged or executed simultaneously if permitted.

[0193] The term "comprising" as used in the specification and claims should not be construed as limiting itself to what follows; it does not exclude other elements or steps. Therefore, it should be interpreted as specifying the presence of the mentioned feature, integral, step, or component, but does not exclude the presence or addition of one or more other features, integrals, steps, or components, or groups thereof. Thus, the statement "device comprising means A and B" should not be limited to a device consisting solely of components A and B.

[0194] The terms "an embodiment" or "an embodiment" as used in this specification mean that a particular feature, structure, or characteristic described in conjunction with that embodiment is included in at least one embodiment of this application. Therefore, the terms "in one embodiment" or "in an embodiment" appearing throughout this specification do not necessarily refer to the same embodiment, but may refer to the same embodiment. Furthermore, in one or more embodiments, the particular features, structures, or characteristics can be combined in any suitable manner, as will be apparent to those skilled in the art from this disclosure.

[0195] Note that the above are merely preferred embodiments and the technical principles employed in this application. Those skilled in the art will understand that this application is not limited to the specific embodiments described herein, and various obvious changes, readjustments, and substitutions can be made without departing from the scope of protection of this application. Therefore, although this application has been described in detail through the above embodiments, this application is not limited to the above embodiments, and may include many other equivalent embodiments without departing from the concept of this application, all of which fall within the scope of protection of this application.

Claims

1. A control method for an energy storage converter, characterized in that, The energy storage converter includes three grid-side ports and two DC-side ports; each grid-side port is connected to a switching device to form a switching device array; the three grid-side ports are connected to the three phases of a three-phase AC grid, using a three-phase symmetrical connection without a neutral wire; the two DC-side ports are connected to the positive and negative poles of the energy storage medium, and are composed of a DC bus capacitor connected in parallel with a battery. The method includes: The DC-side voltage u between the two DC-side ports was detected. dc The grid angular frequency ω and the three-phase current i are obtained by detecting the three phases of the three-phase AC grid through the PLL module. a i b i c ; The three-phase current i a i b i c The Clarke transform is used to obtain the current i in the two-phase stationary coordinate system. α i β ; The current i in the two-phase stationary coordinate system α i β Combining the grid angular frequency ω, the Park transformation is used to obtain the current i in the two-phase rotating coordinate system. d i q and voltage u d ,u q ; Given the reference active power P ref and reactive power Q ref Combining the voltage u in the two-phase rotating coordinate system d ,u q Calculate the reference current in the two-phase rotating coordinate system According to the current i in the two-phase rotating coordinate system d i q and reference current Calculate the current tracking errors e1 and e2 in the two-phase rotating coordinate system; Based on sliding mode control theory, the following sliding mode controller expression in a two-phase rotating coordinate system is obtained by using an exponential reaching law S that incorporates a saturation function; based on the sliding mode controller expression, the control voltage is obtained. Among them, S d ,S q These are the switching control functions for the d-axis and q-axis, respectively; L is the grid-side inductance, R is the grid-side resistance; c1 and c2 are the integral gain coefficients. The control voltage Using the aforementioned grid angular frequency ω, the voltage u in the two-phase stationary coordinate system is obtained by inverse Park transformation. α ,u β ; The voltage u in the two-phase stationary coordinate system α ,u β Based on space vector pulse width modulation, control signals are generated to control the switching device array to control the corresponding switching devices to turn on or off.

2. The method according to claim 1, characterized in that, The exponential reaching law S of the saturation function is introduced as follows: Where s is the system sliding surface; k>0 is the sliding gain coefficient; ε>0 is the boundary layer thickness coefficient; η,l are control parameters; and sat(s) is the linear saturation function.

3. The method according to claim 2, characterized in that, The system's sliding surface incorporates an integral term to eliminate errors, calculated according to the following formula: Wherein, s1 and s2 are the sliding surfaces of the d-axis and q-axis in the two-phase rotating coordinate system dq, respectively.

4. The method according to claim 3, characterized in that, The expression for the sliding mode controller is as follows: Wherein, η1,η2,l1,l2 are calculated based on the corresponding sliding surfaces s1,s2 of the d-axis and q-axis using the following formula. Where n = 1 or 2; δ and σ are parameters that define the boundary layer, 0 < μ < 1, ν > 0; l3 and l4 are positive odd numbers, and l3 > l4.

5. The method according to claim 4, characterized in that, The saturation functions sat(s1) and sat(s2) are calculated using the following formula: Where Δ is the parameter that defines the boundary layer.

6. The method according to claim 1, characterized in that, The reference current and current tracking error are obtained according to the following formula:

7. The method according to claim 1, characterized in that, The control voltage The following formula is used to calculate:

8. A control device for an energy storage converter used to implement the method of claim 1, characterized in that, include: The outer loop calculation module is used to detect the DC-side voltage u between the two DC-side ports. dc ; The grid angular frequency ω and the three-phase current i are obtained by detecting the three phases of the three-phase AC grid using a PLL module. a i b i c ; the three-phase current i a i b i c The Clarke transform is used to obtain the current i in the two-phase stationary coordinate system. α i β The current i in the two-phase stationary coordinate system α i β Combining the grid angular frequency ω, the Park transformation is used to obtain the current i in the two-phase rotating coordinate system. d i q and voltage u d ,u q ; The inner-loop calculation module is used to calculate the given reference active power P. ref and reactive power Q ref Combined with the voltage u d ,u q Calculate the reference current in the two-phase rotating coordinate system According to the current i in the two-phase rotating coordinate system d i q and reference current The current tracking errors e1 and e2 in the two-phase rotating coordinate system are calculated. Based on sliding mode control theory, an exponential reaching law S in the two-phase rotating coordinate system with an introduced saturation function is used to obtain the sliding mode controller expression. Based on the sliding mode controller expression, the control voltage is obtained. The control drive module is used to transfer the control voltage. Using the aforementioned grid angular frequency ω, the voltage u in the two-phase stationary coordinate system is obtained by inverse Park transformation. α ,u β The voltage u in the two-phase stationary coordinate system α ,u β The control signal for the control switching device array is generated based on space vector pulse width modulation to control the conduction or cutoff of the corresponding switching devices.

9. A computing device, characterized in that, include: processor, and A memory having stored program instructions that, when executed by the processor, cause the processor to perform the energy storage converter control method according to any one of claims 1 to 7.

10. A computer-readable storage medium, characterized in that, It stores program instructions that, when executed by a computer, cause the computer to perform the energy storage converter control method according to any one of claims 1 to 7.

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