A method and system for optimizing phase-locked loop parameters of a wind turbine generator system
By solving and simulation optimization of the parameters of the phase-locked loop transfer function, the problem of difficulty in tracking the phase-locked loop during the grid voltage phase jump is solved, and the transient characteristics of the wind turbine and the phase-locked loop are improved.
Patent Information
- Application Number
- CN201810292899.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2018-03-30
- Publication Date
- 2024-12-27
- Estimated Expiration
- 2038-03-30
AI Technical Summary
When the wind turbine voltage phase transitions, the phase-locked loop is difficult to track the phase, affecting the transient characteristics, and the prior art is difficult to effectively solve this problem.
By finding the characteristic equations of unlocked phase loop transfer function, obtaining parameters that affect the response characteristics of the phase locked loop, and adjusting these parameters through simulation analysis to optimize the optimal loop parameters and improve the phase jump of the phase locked loop in the grid voltage in the power grid. Phase tracking performance under
The parameters of the phase locked loop are optimized, and the transient operation characteristics of the wind turbine are improved in the case of phase transition of the grid voltage is achieved, ensuring the phase tracking accuracy of the phase locked loop and the convenience of parameter selection.
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Figure CN108510121B_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the field of wind turbines, and in particular to a method and system for optimizing phase-locked loop parameters of a wind turbine. Background Art
[0002] In recent years, wind power has developed rapidly. As the scale of wind power increases and its proportion in the power system continues to increase, the mutual influence between wind power and the power grid has become more and more complex. As the main model for commercial operation, variable-speed wind turbines can achieve decoupling control of active power and reactive power, and improve the regulation ability and stability of the power system. Variable-speed wind turbines are connected to the power grid through back-to-back inverters. During operation, the inverter and the power grid must be synchronized. The phase-locked loop (PLL) needs to be used to quickly and accurately lock the phase of the power grid. At present, wind turbines generally use a vector control method based on phase-locked synchronization. The phase-locked loop drives the internal potential phase change to achieve synchronous operation with the power grid. Therefore, the performance of the phase-locked loop has an important influence on the transient characteristics of variable-speed wind turbines.
[0003] The phase-locked loop circuit is a typical feedback control circuit that enables the output signal to automatically track the input signal in frequency and phase. During steady-state operation, the grid voltage phase changes slightly, and the phase-locked loop can easily track the grid voltage phase change and achieve accurate phase locking. However, in transient conditions, the grid voltage phase jumps, which makes it difficult for the phase-locked loop to track the phase and affects the transient characteristics of the wind turbine. Therefore, it is worth studying how to solve the problem of grid voltage phase jumps causing difficulties for the phase-locked loop to track the phase. Summary of the invention
[0004] In order to solve the above-mentioned deficiencies in the prior art, the present invention provides a method and system for optimizing the phase-locked loop parameters of a wind turbine. The present invention conducts theoretical analysis and simulation analysis on the loop parameters of the loop filter in the phase-locked loop, theoretically analyzes the influence of the loop parameters on the phase tracking characteristics of the phase-locked loop, and simulates and analyzes the sensitivity analysis of the parameter optimization on the phase tracking improvement capability of the phase-locked loop, thereby optimizing the optimal loop parameters and improving the transient operation characteristics of the wind turbine under the condition of grid voltage phase jump.
[0005] The technical solution provided by the present invention is: a method for optimizing the phase-locked loop parameters of a wind turbine generator set, comprising:
[0006] Calculate the characteristic equation of the phase-locked loop transfer function and obtain the parameters that affect the response characteristics of the phase-locked loop;
[0007] Simulating the wind turbine phase-locked loop operating environment to adjust the parameters that affect the phase-locked loop response characteristics;
[0008] The optimal phase-locked loop parameters are determined based on the phase tracking results obtained by simulation.
[0009] Preferably, the transfer function characteristic equation is as shown below:
[0010] s 2 +k p s+k i =0
[0011] Where: s: frequency self-programming path; k p : proportionality coefficient; k i : integral coefficient.
[0012] Preferably, the step of obtaining the characteristic equation of the phase-locked loop transfer function and acquiring the parameters that affect the response characteristics of the phase-locked loop includes:
[0013] Find the characteristic equation of the unlocked phase loop transfer function, and express the characteristic root of the transfer function characteristic equation by the following formula:
[0014]
[0015] Where: s1: the first characteristic root of the characteristic equation of the transfer function; s2: the second characteristic root of the characteristic equation of the transfer function;
[0016] Among them, the parameter that affects the response characteristics of the phase-locked loop is the proportional coefficient k p and the integration coefficient k i .
[0017] Preferably, the simulating wind turbine phase-locked loop operating environment to adjust the parameters affecting the phase-locked loop response characteristics includes:
[0018] According to the transient response characteristics of the phase-locked loop and the parameters affecting the response characteristics of the phase-locked loop, a response expression of the phase-locked loop under a grid voltage phase jump is established;
[0019] Solving the response expression to obtain frequency domain characteristic roots reflecting the performance of the phase-locked loop;
[0020] In a simulated wind turbine phase-locked loop operating environment, the parameters affecting the phase-locked loop response characteristics are adjusted according to the frequency domain characteristic roots to obtain a phase tracking result.
[0021] Preferably, the response expression of the phase-locked loop under the grid voltage phase jump is as shown in the following formula:
[0022]
[0023] Where: The response of the phase-locked loop to grid voltage phase jumps; Grid voltage phase jump value; G(s): PLL transfer function; s: frequency self-programming path; k p : proportionality coefficient; k i : integral coefficient.
[0024] Preferably, solving the response expression obtains a frequency domain characteristic root reflecting the performance of the phase-locked loop, as shown in the following formula:
[0025]
[0026] Where: Frequency domain characteristic root; k p : proportionality coefficient; k i : integral coefficient.
[0027] Preferably, the step of adjusting the parameters affecting the response characteristics of the phase-locked loop to obtain the phase tracking result according to the frequency domain characteristic roots in the simulated wind turbine phase-locked loop operating environment includes:
[0028] When the phase angle jumps in the operating environment of the wind turbine phase-locked loop, the integral coefficient is kept unchanged, and the proportional coefficient is increased until the overshoot of the phase-locked loop response remains unchanged, and the output phase tracking result includes the current proportional coefficient;
[0029] The current proportional coefficient is kept unchanged, and the integral coefficient is increased until the response speed of the phase-locked loop remains unchanged, and the output phase tracking result includes the current integral coefficient.
[0030] Preferably, determining the optimal phase-locked loop parameters according to the phase tracking results obtained by simulation includes:
[0031] If the phase tracking result satisfies the convergence function, the proportional coefficient and the integral coefficient in the phase tracking result are optimal phase-locked loop parameters.
[0032] Preferably, the convergence function is represented by the following formula:
[0033]
[0034] Where: The N-1th phase tracking result; f(θ): the maximum deviation between the Nth phase tracking result curve and the N-1th phase tracking result curve; a: the preset error optimization target value;
[0035] The maximum deviation f(θ) between the Nth phase tracking result curve and the N-1th result curve is expressed by the following formula:
[0036]
[0037] Where: Nth phase tracking result.
[0038] Based on the same inventive concept, the present invention also provides a system for optimizing the phase-locked loop parameters of a wind turbine generator set, comprising:
[0039] A solution module, used for solving the characteristic equation of the phase-locked loop transfer function and obtaining the parameters that affect the response characteristics of the phase-locked loop;
[0040] A simulation module, used for simulating the operating environment of the phase-locked loop of the wind turbine generator set to adjust the parameters that affect the response characteristics of the phase-locked loop;
[0041] The determination module is used to determine the optimal phase-locked loop parameters according to the phase tracking results obtained by simulation.
[0042] Preferably, the solution module includes:
[0043] The first solving unit is used to express the characteristic equation of the transfer function by the following formula:
[0044] s 2 +k p s+k i =0
[0045] Where: s: frequency self-programming path; k p : proportionality coefficient; k i : integration coefficient;
[0046] The second solving unit is used to solve the characteristic equation of the unlocked phase loop transfer function, and the characteristic root of the characteristic equation of the transfer function is expressed by the following formula:
[0047]
[0048] Where: s1: the first characteristic root of the characteristic equation of the transfer function; s2: the second characteristic root of the characteristic equation of the transfer function;
[0049] Parameter unit, used to determine the parameter that affects the response characteristics of the phase-locked loop as the proportional coefficient k p and the integration coefficient k i .
[0050] Preferably, the simulation module comprises:
[0051] Establishing a submodule for establishing a response expression of the phase-locked loop under a grid voltage phase jump according to the transient response characteristics of the phase-locked loop and the parameters affecting the response characteristics of the phase-locked loop;
[0052] A solving submodule, used for solving the response expression to obtain a frequency domain characteristic root reflecting the performance of the phase-locked loop;
[0053] The regulating submodule is used to adjust the parameters affecting the response characteristics of the phase-locked loop according to the frequency domain characteristic roots in the simulated wind turbine phase-locked loop operating environment to obtain a phase tracking result.
[0054] Preferably, the regulating submodule comprises:
[0055] The first regulating unit is used for keeping the integral coefficient unchanged and increasing the proportional coefficient until the overshoot of the phase-locked loop response remains unchanged when the phase angle jumps in the phase-locked loop operating environment of the wind turbine generator set, and outputting the phase tracking result including the current proportional coefficient;
[0056] The second regulating unit is used to keep the current proportional coefficient unchanged and increase the integral coefficient until the response speed of the phase-locked loop remains unchanged, and the output phase tracking result includes the current integral coefficient.
[0057] Preferably, the determining module includes:
[0058] A determination unit, configured to determine that if the phase tracking result satisfies a convergence function, the proportional coefficient and the integral coefficient in the phase tracking result are optimal phase-locked loop parameters;
[0059] The conditional unit is used to express the convergence function by the following formula:
[0060]
[0061] Where: The N-1th phase tracking result; f(θ): the maximum deviation between the Nth phase tracking result curve and the N-1th phase tracking result curve; a: the preset error optimization target value;
[0062] It is also used to express the maximum deviation f(θ) between the Nth phase tracking result curve and the N-1th result curve by the following formula:
[0063]
[0064] Where: Nth phase tracking result.
[0065] Compared with the closest prior art, the technical solution provided by the present invention has the following beneficial effects:
[0066] The technical solution provided by the present invention calculates the characteristic equation of the phase-locked loop transfer function and obtains the parameters that affect the response characteristics of the phase-locked loop; simulates the operating environment of the phase-locked loop of the wind turbine to adjust the parameters that affect the response characteristics of the phase-locked loop; determines the optimal phase-locked loop parameters based on the phase tracking results obtained by simulation; can optimize the best phase-locked loop parameters and avoid blindly amplifying the phase-locked loop parameters; and solves the difficulty of phase-locked loop tracking phase caused by the jump of grid voltage phase by determining the optimal phase-locked loop parameters.
[0067] The technical solution provided by the present invention not only meets the phase tracking accuracy of the phase-locked loop, but also takes into account the convenience of parameter selection.
[0068] The technical solution provided by the present invention improves the phase tracking performance of the phase-locked loop under the condition of grid voltage phase jump, and improves the transient characteristics of the wind turbine generator set. BRIEF DESCRIPTION OF THE DRAWINGS
[0069] Figure 1 A flow chart of a method for optimizing phase-locked loop parameters of a wind turbine generator system according to the present invention;
[0070] Figure 2 It is a schematic diagram of the basic structure of the phase-locked loop of the variable speed wind turbine of the present invention;
[0071] Figure 3 Flow chart of a method for optimizing phase-locked loop parameters based on sensitivity analysis in an embodiment of the present invention;
[0072] Figure 4 A schematic diagram of coordinate system conversion in an embodiment of the present invention;
[0073] Figure 5 A schematic diagram of a phase-locked loop transfer function structure in an embodiment of the present invention;
[0074] Figure 6 Schematic diagram of phase-locked loop response characteristics under grid voltage phase jump in an embodiment of the present invention;
[0075] Figure 7 Schematic diagram of a phase-locked loop phase tracking simulation curve under a grid voltage phase jump in an embodiment of the present invention;
[0076] Figure 8 It is a schematic diagram of a local enlargement of the tracking simulation curve in an embodiment of the present invention. DETAILED DESCRIPTION
[0077] In order to better understand the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are 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.
[0078] Based on the present invention, a method and system for optimizing phase-locked loop parameters of a wind turbine are provided. Two embodiments are provided in this embodiment:
[0079] Example 1
[0080] Figure 1 The flowchart of the method for optimizing the phase-locked loop parameters of a wind turbine generator system according to the present invention is as follows: Figure 1 As shown, including:
[0081] Step S101, calculating a characteristic equation of a phase-locked loop transfer function to obtain parameters that affect the response characteristics of the phase-locked loop;
[0082] Step S102, simulating the operating environment of the wind turbine phase-locked loop to adjust the parameters that affect the response characteristics of the phase-locked loop;
[0083] Step S103, determining optimal phase-locked loop parameters according to the phase tracking result obtained by simulation.
[0084] Step S101, finding the characteristic equation of the phase-locked loop transfer function and obtaining the parameters that affect the response characteristics of the phase-locked loop, including:
[0085] The transfer function characteristic equation is shown in the following formula:
[0086] s 2 +k p s+k i =0
[0087] Where: s: frequency self-programming path; k p : proportionality coefficient; k i : integral coefficient.
[0088] Find the characteristic equation of the unlocked phase loop transfer function, and express the characteristic root of the transfer function characteristic equation by the following formula:
[0089]
[0090] Where: s1: the first characteristic root of the characteristic equation of the transfer function; s2: the second characteristic root of the characteristic equation of the transfer function;
[0091] Among them, the parameter that affects the response characteristics of the phase-locked loop is the proportional coefficient k p and the integration coefficient k i .
[0092] Step S102, simulating the wind turbine phase-locked loop operating environment to adjust the parameters that affect the phase-locked loop response characteristics, includes:
[0093] According to the transient response characteristics of the phase-locked loop and the parameters affecting the response characteristics of the phase-locked loop, a response expression of the phase-locked loop under a grid voltage phase jump is established;
[0094] Solving the response expression to obtain frequency domain characteristic roots reflecting the performance of the phase-locked loop;
[0095] In a simulated wind turbine phase-locked loop operating environment, the parameters affecting the phase-locked loop response characteristics are adjusted according to the frequency domain characteristic roots to obtain a phase tracking result.
[0096] Among them, the response expression of the phase-locked loop under the grid voltage phase jump is shown in the following formula:
[0097]
[0098] Where: The response of the phase-locked loop to grid voltage phase jumps; Grid voltage phase jump value; G(s): PLL transfer function; s: frequency self-programming path; k p : proportionality coefficient; k i : integral coefficient.
[0099] Furthermore, the response expression is solved to obtain the frequency domain characteristic root reflecting the performance of the phase-locked loop, as shown in the following formula:
[0100]
[0101] Where: Frequency domain characteristic root; k p : proportionality coefficient; k i : integral coefficient.
[0102] Further, in the simulated wind turbine phase-locked loop operating environment, according to the frequency domain characteristic root, the parameters affecting the phase-locked loop response characteristics are adjusted to obtain a phase tracking result, including:
[0103] When the phase angle jumps in the operating environment of the wind turbine phase-locked loop, the integral coefficient is kept unchanged, and the proportional coefficient is increased until the overshoot of the phase-locked loop response remains unchanged, and the output phase tracking result includes the current proportional coefficient;
[0104] The current proportional coefficient is kept unchanged, and the integral coefficient is increased until the response speed of the phase-locked loop remains unchanged, and the output phase tracking result includes the current integral coefficient.
[0105] Step S103, determining optimal phase-locked loop parameters according to the phase tracking result obtained by simulation, including:
[0106] If the phase tracking result satisfies the convergence function, the proportional coefficient and the integral coefficient in the phase tracking result are optimal phase-locked loop parameters.
[0107] Wherein, the convergence function is represented by the following formula:
[0108]
[0109] Where: The N-1th phase tracking result; f(θ): the maximum deviation between the Nth phase tracking result curve and the N-1th phase tracking result curve; a: the preset error optimization target value;
[0110] The maximum deviation f(θ) between the Nth phase tracking result curve and the N-1th result curve is expressed by the following formula:
[0111]
[0112] Where: Nth phase tracking result.
[0113] Example 2
[0114] Figure 2 The basic structure diagram of the phase-locked loop of a typical variable-speed wind turbine is shown in Figure 2. Figure 2 As shown in the figure, the phase-locked loop is mainly composed of three parts: phase detector (PD), loop filter (Low Pass Filter, LPF) and voltage controlled oscillator (VCO).
[0115] There are various forms of phase-locked loops in practical applications, but they are all evolved from this basic loop.
[0116] The working principle of the phase-locked loop is as follows: the phase detector (PD) compares the phase of the periodic input signal with the phase of the output signal of the voltage-controlled oscillator to detect the phase difference between the input signal phase and the feedback signal phase. The error voltage is filtered by the loop filter (LF). The loop filter can suppress the noise and high-frequency signal part of the phase detector output. In addition to its low-pass characteristics, it plays a decisive role in the adjustment of loop parameters and has an important impact on various performances of the loop. The output of the loop filter is used as a control voltage to be sent to the voltage-controlled oscillator (VCO). The voltage-controlled oscillator has an inherent integral link and the output is an instantaneous phase angle. There are various forms of phase-locked loops in practical applications, but they are all evolved from this basic loop. PLL compares the input signal with the output signal of the VCO to generate a voltage signal corresponding to the phase difference between the two signals, in which the high-frequency part and noise are filtered out by the LPF. The above voltage signal acts on the VCO to pull the VCO frequency to the input signal frequency until the frequency difference is eliminated and enters the locked state. At this time, the frequency difference between the output signal and the input signal is 0, and the phase angle difference is fixed.
[0117] In this embodiment, by studying the transient characteristics of the wind turbine under the condition of grid voltage phase jump, based on the analysis of the impact of phase-locked loop parameter changes on the phase tracking performance, the sensitivity analysis of the phase-locked loop phase performance of the phase-locked loop is performed, and the best phase-locked loop parameters are selected to achieve the optimal phase-locked loop phase tracking performance, thereby improving the transient operating characteristics of the wind turbine under the condition of grid voltage phase jump.
[0118] The specific process of the method for optimizing the phase-locked loop parameters of a wind turbine in this embodiment is as follows: Figure 3 As shown, the following steps are included:
[0119] I. Build a phase-locked loop transfer function model, establish an analytical expression for the transfer function, analyze the characteristic equation of the transfer function, obtain the characteristic value that expresses the performance of the phase-locked loop, and determine the key parameters of the phase-locked loop;
[0120] II. Theoretically analyze the transient response characteristics of the phase-locked loop, establish the frequency domain analytical expression of the phase-locked loop under the condition of grid voltage phase jump, and obtain the frequency domain characteristic roots that reflect the performance of the phase-locked loop through the analytical equation;
[0121] III. Simulate and analyze the impact of changes in phase-locked loop parameters on phase-locked characteristics when the grid voltage phase jumps, carry out sensitivity analysis, and optimize the phase-locked loop parameters.
[0122] Furthermore, in step I, a phase-locked loop transfer function model is constructed, an analytical expression of the transfer function is established, a characteristic equation of the transfer function is analyzed, characteristic values expressing the performance of the phase-locked loop are obtained, and key parameters of the phase-locked loop are determined.
[0123] Variable speed wind turbine control is usually implemented in a synchronous rotating coordinate system, so the phase-locked loop response characteristics are studied in the synchronous rotating coordinate system. The phase-locked loop consists of two parts: one is the Clark and Park transformation part, and the other is the feedback system containing the proportional integral link. The phase-locked loop converts the three-phase voltage in the abc coordinate system into the AC-DC axis voltage in the positive sequence rotating coordinate system through Clark and Park transformation.
[0124] Figure 4 This is a schematic diagram of coordinate system conversion. Taking the quadrature-axis voltage equal to 0 as the control target, the direct-axis voltage can be controlled to track the grid voltage and obtain the phase of each phase voltage. The phase-locked loop uses the projection of the voltage vector on the quadrature axis as the phase detection and the proportional-integral link as the loop filter.
[0125] The dynamic performance of the phase-locked loop mainly depends on the PI parameters of the loop filter.
[0126] Figure 5 The figure shows the structure block diagram of the phase-locked loop transfer function, in which the loop filter generally adopts a PI structure, as shown in equation (1).
[0127]
[0128] Where, s: frequency self-programming path; k p : proportionality coefficient; k i : integral coefficient.
[0129] The phase-locked loop under the typical basic structure can be expressed by the transfer function shown in equation (2).
[0130]
[0131] Among them, θ(s) is the input signal, θ e (s) is the output signal.
[0132] The characteristic equation of the phase-locked loop transfer function is shown in equation (3).
[0133] s 2 +k p s+k i =0………………………………(3)
[0134] The characteristic roots of the characteristic equation are shown in formula (4).
[0135]
[0136] From the characteristic roots of the phase-locked loop characteristic equation, it can be seen that the response characteristics of the phase-locked loop depend on k p and k i These two parameters.
[0137] Furthermore, in step II, the transient response characteristics of the phase-locked loop are theoretically analyzed, and a frequency domain analytical expression of the phase-locked loop under the condition of a grid voltage phase jump is established. The frequency domain characteristic roots reflecting the performance of the phase-locked loop are obtained by the analytical equation.
[0138] When the grid voltage phase angle changes, the frequency domain expression of the phase-locked loop transfer function will change. Assume that the grid voltage phase angle changes to The frequency expression of phase angle jump is shown in formula (5).
[0139]
[0140] The response of the phase-locked loop to the grid voltage phase jump is shown in equation (6).
[0141]
[0142] For different proportionality coefficients k p and the integration coefficient k i After discussing them separately, we can get the transient response characteristics of the phase-locked loop under phase angle jump as shown in formula (7).
[0143]
[0144] At different scale factors k p and the integration coefficient k i Under the value, the transient response characteristics of the phase-locked loop under phase angle jump can be obtained as follows Figure 6 shown.
[0145] The indicators of phase-locked loop performance are phase-locked loop response overshoot and phase-locked loop response speed.
[0146] When the phase angle jumps, the smaller the proportional coefficient, the greater the overshoot of the phase-locked loop response, and the worse the performance of the phase-locked loop. The larger the proportional coefficient, the smaller the overshoot of the phase-locked loop response. After the proportional coefficient reaches a certain value, the effect of increasing the proportional coefficient on improving the overshoot of the phase-locked loop becomes smaller and smaller. The influence of the proportional coefficient on the phase-locked performance of the phase-locked loop has obvious exponential function characteristics.
[0147] When the proportional coefficient is the same, the larger the integral coefficient, the faster the phase-locked loop responds, the better the phase-locked loop performance, and helps improve the overshoot of the phase-locked loop. When the integral coefficient reaches a certain value, the phase-locked loop can basically track the phase change of the power grid, and the change of the proportional coefficient will no longer have a significant impact on the performance of the phase-locked loop. Compared with the proportional coefficient, the integral coefficient has a greater impact on the phase-locked performance of the phase-locked loop.
[0148] Furthermore, in step III, the influence of the change of the phase-locked loop parameters on the phase-locked characteristics when the grid voltage phase jumps is simulated and analyzed, a sensitivity analysis is carried out, and the phase-locked loop parameters are optimized.
[0149] Set the grid voltage phase jump, simulate and analyze the sensitivity of the phase-locked loop parameter change to the phase-locked performance, first set the integral parameter to a constant value, continuously change the proportional parameter, simulate and analyze the phase-locked performance of the phase-locked loop, and determine the sensitivity of the proportional parameter;
[0150] Then the proportional parameter is set to a constant value, the integral parameter is continuously increased, the phase-locked performance of the phase-locked loop is simulated and analyzed, and the sensitivity of the integral parameter is determined;
[0151] When the improvement of the PLL performance is no longer obvious when the proportional parameter and the integral parameter continue to increase, that is, when the deviation between the Nth phase tracking result and the N-1th result is less than a certain value, it is considered that the proportional parameter and the integral parameter have reached the optimum, thus determining the optimal PLL parameters.
[0152] The convergence function expression of the phase-locked loop parameter sensitivity analysis is shown in formula (8):
[0153]
[0154] in, is the Nth phase tracking result; is the N-1th phase tracking result; f(θ) is the maximum deviation between the N-th phase tracking result curve and the N-1th phase tracking result curve; a is the error optimization target value, which can be set according to actual needs, for example, it is set to 2% in this example.
[0155] Set the integral coefficient k i =400, continuously increasing the proportionality factor k p , for example, the values can be 10, 100, 200, 400, 800, and 1000 respectively. The phase-locked loop phase-locked tracking curve is as follows Figure 7 shown. Figure 8 The embodiment of the present invention is directed to Figure 7 The tracking simulation curve is zoomed in from 0.2s to 0.25s. The proportional coefficient k p The smaller the value, the greater the overshoot of the phase-locked loop, and the worse the phase-locked effect; the proportional coefficient k p The larger the value, the better the phase-locked performance of the phase-locked loop.
[0156] And when the proportionality coefficient k p When the value is small, after the fault is removed, when the phase jumps, the phase-locked loop phase-locked curve oscillates, and a larger proportional coefficient k is used. p The value can effectively suppress oscillation and improve the phase-locked loop effect. However, it can also be seen that when the phase-locked loop proportional coefficient k p After the value exceeds 800, continue to increase the proportional coefficient k p The effect of the value on improving the phase-locked performance of the phase-locked loop is no longer obvious.
[0157] Such as k p When the values are 600 and 800 respectively, f(θ)=1.612, then When k is greater than the set target value by 2%, p When the values are 800 and 1000 respectively, f(θ)=1.574, then is 2% less than the set target value, which means k p When the value is 800, the target value requirement can be met.
[0158] The same method can be used to obtain the optimal k i Value, in this case k i The optimal value is 800. Therefore, the optimal matching parameter of the phase-locked loop in this embodiment is k p =800, k i =800.
[0159] Based on the same inventive concept, this embodiment also provides a system for optimizing the phase-locked loop parameters of a wind turbine generator set, including:
[0160] A solution module, used for solving the characteristic equation of the phase-locked loop transfer function and obtaining the parameters that affect the response characteristics of the phase-locked loop;
[0161] A simulation module, used for simulating the operating environment of the phase-locked loop of the wind turbine generator set to adjust the parameters that affect the response characteristics of the phase-locked loop;
[0162] The determination module is used to determine the optimal phase-locked loop parameters according to the phase tracking results obtained by simulation.
[0163] In an embodiment, the solution module includes:
[0164] The first solving unit is used to express the characteristic equation of the transfer function by the following formula:
[0165] s 2 +k p s+k i =0
[0166] Where: s: frequency self-programming path; k p : proportionality coefficient; k i : integration coefficient;
[0167] The second solving unit is used to solve the characteristic equation of the unlocked phase loop transfer function, and the characteristic root of the characteristic equation of the transfer function is expressed by the following formula:
[0168]
[0169] Where: s1: the first characteristic root of the characteristic equation of the transfer function; s2: the second characteristic root of the characteristic equation of the transfer function;
[0170] Parameter unit, used to determine the parameter that affects the response characteristics of the phase-locked loop as the proportional coefficient k p and the integration coefficient k i .
[0171] In the embodiment, the simulation module includes:
[0172] Establishing a submodule for establishing a response expression of the phase-locked loop under a grid voltage phase jump according to the transient response characteristics of the phase-locked loop and the parameters affecting the response characteristics of the phase-locked loop;
[0173] A solving submodule, used for solving the response expression to obtain a frequency domain characteristic root reflecting the performance of the phase-locked loop;
[0174] The regulating submodule is used to adjust the parameters affecting the response characteristics of the phase-locked loop according to the frequency domain characteristic roots in the simulated wind turbine phase-locked loop operating environment to obtain a phase tracking result.
[0175] In an embodiment, the regulating submodule comprises:
[0176] The first regulating unit is used for keeping the integral coefficient unchanged and increasing the proportional coefficient until the overshoot of the phase-locked loop response remains unchanged when the phase angle jumps in the phase-locked loop operating environment of the wind turbine generator set, and outputting the phase tracking result including the current proportional coefficient;
[0177] The second regulating unit is used to keep the current proportional coefficient unchanged and increase the integral coefficient until the response speed of the phase-locked loop remains unchanged, and the output phase tracking result includes the current integral coefficient.
[0178] In an embodiment, the determining module includes:
[0179] A determination unit, configured to determine that if the phase tracking result satisfies a convergence function, the proportional coefficient and the integral coefficient in the phase tracking result are optimal phase-locked loop parameters;
[0180] The conditional unit is used to express the convergence function by the following formula:
[0181]
[0182] Where: The N-1th phase tracking result; f(θ): the maximum deviation between the N-th phase tracking result curve and the N-1th phase tracking result curve; a: the preset error optimization target value;
[0183] It is also used to express the maximum deviation f(θ) between the Nth phase tracking result curve and the N-1th result curve by the following formula:
[0184]
[0185] Where: Nth phase tracking result.
[0186] It can be seen that this patent adopts the sensitivity analysis method, which can not only select the best phase-locked loop parameters, but also avoid blindly amplifying the phase-locked loop parameters. On the basis of meeting the phase tracking accuracy of the phase-locked loop, it also takes into account the convenience of parameter selection. It improves the phase tracking performance of the phase-locked loop under the condition of grid voltage phase jump and improves the transient characteristics of the wind turbine.
[0187] Those skilled in the art will appreciate that the embodiments of the present application may be provided as methods, systems, or computer program products. Therefore, the present application may adopt the form of a complete hardware embodiment, a complete software embodiment, or an embodiment in combination with software and hardware. Moreover, the present application may adopt the form of a computer program product implemented in one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) that contain computer-usable program code.
[0188] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1A device that provides the functions specified in a block or multiple blocks.
[0189] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture including an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.
[0190] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.
[0191] The above are merely embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention are included in the scope of the claims of the present invention to be approved.
Claims
1. A method for optimizing phase-locked loop parameters of a wind turbine generator system, characterized in that: include: Calculate the characteristic equation of the phase-locked loop transfer function and obtain the parameters that affect the response characteristics of the phase-locked loop; Simulating the wind turbine phase-locked loop operating environment to adjust the parameters that affect the phase-locked loop response characteristics; Determine the optimal phase-locked loop parameters based on the phase tracking results obtained by simulation; The transfer function characteristic equation is shown in the following formula: s 2 +k p s+k i =0 Where: s: frequency self-programming path; k p : proportionality coefficient; k i : integration coefficient; The step of obtaining the characteristic equation of the phase-locked loop transfer function and obtaining the parameters that affect the response characteristics of the phase-locked loop includes: Find the characteristic equation of the unlocked phase loop transfer function, and express the characteristic root of the transfer function characteristic equation by the following formula: Where: s1: the first characteristic root of the characteristic equation of the transfer function; s2: the second characteristic root of the characteristic equation of the transfer function; Among them, the parameter that affects the response characteristics of the phase-locked loop is the proportional coefficient k p and the integration coefficient k i ; The simulating wind turbine phase-locked loop operating environment to adjust the parameters affecting the phase-locked loop response characteristics includes: According to the transient response characteristics of the phase-locked loop and the parameters affecting the response characteristics of the phase-locked loop, a response expression of the phase-locked loop under a grid voltage phase jump is established; Solving the response expression to obtain frequency domain characteristic roots reflecting the performance of the phase-locked loop; In a simulated wind turbine phase-locked loop operating environment, according to the frequency domain characteristic root, the parameters affecting the phase-locked loop response characteristics are adjusted to obtain a phase tracking result; The response expression of the phase-locked loop under the grid voltage phase jump is shown in the following formula: Where: The response of the phase-locked loop to grid voltage phase jumps; Grid voltage phase jump value; G(s): PLL transfer function; s: frequency self-programming path; k p : proportionality coefficient; k i : integration coefficient; The frequency domain characteristic root reflecting the performance of the phase-locked loop is obtained by solving the response expression, as shown in the following formula: Where: Frequency domain characteristic root; k p : proportionality coefficient; k i : integration coefficient; The step of adjusting the parameters affecting the response characteristics of the phase-locked loop to obtain the phase tracking result according to the frequency domain characteristic roots in the simulated wind turbine phase-locked loop operating environment includes: When the phase angle jumps in the operating environment of the wind turbine phase-locked loop, the integral coefficient is kept unchanged, and the proportional coefficient is increased until the overshoot of the phase-locked loop response remains unchanged, and the output phase tracking result includes the current proportional coefficient; The current proportional coefficient is kept unchanged, and the integral coefficient is increased until the response speed of the phase-locked loop remains unchanged, and the output phase tracking result includes the current integral coefficient.
2. The method for optimizing the phase-locked loop parameters of a wind turbine generator set according to claim 1, characterized in that: Determining the optimal phase-locked loop parameters according to the phase tracking results obtained by simulation includes: If the phase tracking result satisfies the convergence function, the proportional coefficient and the integral coefficient in the phase tracking result are optimal phase-locked loop parameters.
3. The method for optimizing the phase-locked loop parameters of a wind turbine generator set according to claim 2, characterized in that: The convergence function is expressed by the following formula: Where: The N-1th phase tracking result; f(θ): the maximum deviation between the Nth phase tracking result curve and the N-1th phase tracking result curve; a: preset error optimization target value; The maximum deviation f(θ) between the Nth phase tracking result curve and the N-1th result curve is expressed by the following formula: Where: Nth phase tracking result.
4. A system for optimizing phase-locked loop parameters of a wind turbine generator, characterized in that: include: A solution module, used for solving the characteristic equation of the phase-locked loop transfer function and obtaining the parameters that affect the response characteristics of the phase-locked loop; A simulation module, used for simulating the operating environment of the phase-locked loop of the wind turbine generator set to adjust the parameters that affect the response characteristics of the phase-locked loop; A determination module, used to determine optimal phase-locked loop parameters according to the phase tracking results obtained by simulation; The solution module comprises: The first solving unit is used to express the characteristic equation of the transfer function by the following formula: s 2 +k p s+k i =0 Where: s: frequency self-programming path; k p : proportionality coefficient; k i : integration coefficient; The second solving unit is used to solve the characteristic equation of the unlocked phase loop transfer function, and the characteristic root of the characteristic equation of the transfer function is expressed by the following formula: Where: s1: the first characteristic root of the characteristic equation of the transfer function; s2: the second characteristic root of the characteristic equation of the transfer function; Parameter unit, used to determine the parameter that affects the response characteristics of the phase-locked loop as the proportional coefficient k p and the integration coefficient k i ; The simulation module comprises: Establishing a submodule for establishing a response expression of the phase-locked loop under a grid voltage phase jump according to the transient response characteristics of the phase-locked loop and the parameters affecting the response characteristics of the phase-locked loop; A solving submodule, used for solving the response expression to obtain a frequency domain characteristic root reflecting the performance of the phase-locked loop; A regulating submodule, used to build according to the frequency domain characteristic root in the simulated wind turbine phase-locked loop operating environment, and to adjust the parameters affecting the phase-locked loop response characteristics to obtain a phase tracking result; The response expression of the phase-locked loop under the grid voltage phase jump is shown in the following formula: Where: The response of the phase-locked loop to grid voltage phase jumps; Grid voltage phase jump value; G(s): PLL transfer function; s: frequency self-programming path; k p : proportionality coefficient; k i : integration coefficient; The regulating submodule comprises: The first regulating unit is used for keeping the integral coefficient unchanged and increasing the proportional coefficient until the overshoot of the phase-locked loop response remains unchanged when the phase angle jumps in the phase-locked loop operating environment of the wind turbine generator set, and outputting the phase tracking result including the current proportional coefficient; The second regulating unit is used to keep the current proportional coefficient unchanged and increase the integral coefficient until the response speed of the phase-locked loop remains unchanged, and the output phase tracking result includes the current integral coefficient.
5. The system for optimizing the phase-locked loop parameters of a wind turbine generator set according to claim 4, characterized in that: The determining module comprises: A determination unit, configured to determine that if the phase tracking result satisfies a convergence function, the proportional coefficient and the integral coefficient in the phase tracking result are optimal phase-locked loop parameters; The conditional unit is used to express the convergence function by the following formula: Where: The N-1th phase tracking result; f(θ): the maximum deviation between the Nth phase tracking result curve and the N-1th phase tracking result curve; a: the preset error optimization target value; It is also used to express the maximum deviation f(θ) between the Nth phase tracking result curve and the N-1th result curve by the following formula: Where: Nth phase tracking result.