A high-proportion renewable energy power quality regulation resource coordination-autonomy method

Abstract

The application provides a high-proportion renewable energy power quality regulation resource coordination-autonomy method, and belongs to the field of energy, comprising: constructing a phase angle feedforward VSG single-machine active-frequency control model; constructing a phase angle feedforward compensation VSG system active-frequency response model according to the phase angle feedforward VSG (virtual synchronous generator) single-machine active-frequency control model; deriving a phase angle feedforward parameter optimal configuration method of the phase angle feedforward compensation VSG system active-frequency response model, realizing autonomous parameter matching and oscillation suppression of a multi-VSG system through construction of a three-layer control architecture of "local perception-neighborhood coordination-global stability", eliminating active oscillation after disturbance, and realizing high-proportion renewable energy power quality regulation resource coordination-autonomy. While realizing coordinated suppression of active oscillation, the application completely retains the inertia response regulation capability of the system.

Description

Technical Field

[0001] This invention belongs to the field of energy, and specifically relates to a collaborative-autonomous method for regulating power quality with a high proportion of renewable energy. Background Technology

[0002] With the rapid development of new energy power generation technologies, distributed microgrids with high proportions of photovoltaic and wind power are developing rapidly, and their voltage and frequency stability control in islanded mode faces new challenges. Virtual synchronous generator (VSG) technology, due to its ability to autonomously construct grid voltage and frequency, has become a core means of grid-based control, significantly improving system transient stability by simulating the inertia-damping characteristics of synchronous motors. However, in engineering practice, it has been found that multi-machine cooperative operation systems often experience active power overshoot and frequency oscillations during dynamic processes due to the mismatch between the adjustment of resource parameters (inertia / damping coefficient) and network impedance, and may even induce system instability under extreme conditions. Existing improvement schemes mainly proceed in two directions: one is to optimize unit-level control parameters through intelligent algorithms; the other is to construct a local impedance compensation network. However, the former has engineering applicability issues such as difficulty in multi-dimensional parameter cooperative optimization and poor algorithm convergence, while the latter may weaken the system's inertial response characteristics and affect the transient stability margin. More importantly, existing research generally has two theoretical limitations: the compensation effect of virtual impedance is strongly coupled with network parameters, and existing parameter optimization models have not yet established an impedance matching constraint mechanism for multi-machine cooperative operation. This often leads to a trade-off between oscillation suppression and dynamic performance in practical systems, exposing the inherent shortcomings of traditional hierarchical control architectures in system-level coordinated regulation. Therefore, there is an urgent need for a new power quality regulation method based on resource coordination and autonomy mechanisms. Summary of the Invention

[0003] To address the aforementioned technical problems, this invention provides a resource-coordinated and autonomous method for power quality regulation of high-proportion renewable energy. It proposes a multi-machine coordinated and autonomous regulation method based on phase angle feedforward compensation in a microgrid islanded operation environment. By constructing a distributed phase angle feedforward compensation network, while maintaining the autonomous regulation capability of the classic active-frequency loop of the VSG, a system-level phase angle coordination mechanism is innovatively introduced. This method establishes an autonomous matching relationship between multi-machine parameters and network impedance by dynamically correcting the active power output phase of each regulation unit. This achieves coordinated suppression of active power oscillations while fully preserving the system's inertial response regulation capability.

[0004] To achieve the above objectives, the present invention adopts the following technical solution:

[0005] A collaborative-autonomous method for high-proportion renewable energy power quality regulation resources includes the following steps:

[0006] Step 1: Construct a single-unit active power-frequency control model for the phase-forward VSG;

[0007] Step 2: Based on the active-frequency control model of a single phase-forward VSG unit, construct the active-frequency response model of the phase-forward compensated VSG system;

[0008] Step 3: Derive the optimal configuration method of phase angle feedforward parameters for the active power-frequency response model of the phase angle feedforward compensation VSG system. By constructing a three-layer control architecture of "local sensing-neighborhood cooperation-global stability", autonomous parameter matching and oscillation suppression of multiple VSG systems are realized, active power oscillation after disturbance is eliminated, and high-proportion renewable energy power quality regulation resource coordination-autonomy is achieved.

[0009] Beneficial effects:

[0010] 1. This invention constructs a two-layer control paradigm of "autonomous adjustment-cooperative compensation", which effectively decouples the coupling relationship between parameter optimization and impedance compensation;

[0011] 2. This invention employs a distributed feedforward compensation mechanism to avoid communication dependencies of the central controller;

[0012] 3. This invention only requires maintaining the consistency of phase compensation parameters when expanding the system, and has natural topology adaptability, providing a brand-new power quality regulation solution for high-proportion renewable energy systems. Attached Figure Description

[0013] Figure 1 Block diagram of active power control for VSG with phase angle feedforward compensation;

[0014] Figure 2 A microgrid topology diagram for n VSGs operating in parallel;

[0015] Figure 3 The active-frequency response model diagram for applying phase angle feedforward control to a microgrid system with n VSGs in parallel;

[0016] Figure 4a The graph shows the power and frequency changes of each unit when phase angle feedforward compensation control is not used.

[0017] Figure 4b The diagram shows the power response and frequency variation of each VSG when the phase angle feedforward compensation control method described in this invention is used.

[0018] Figure 5 This is a flowchart of a resource-coordinated autonomous method for regulating power quality with a high proportion of renewable energy, according to the present invention. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0020] like Figure 5 As shown, the present invention provides a resource-coordinated autonomous method for high-proportion renewable energy power quality regulation, comprising the following steps:

[0021] Step 1: Construct a single-unit active power-frequency control model for the phase-forward VSG;

[0022] Step 2: Based on the active-frequency control model of a single phase-forward VSG unit, construct the active-frequency response model of the phase-forward compensated VSG system;

[0023] Step 3: Derive the optimal configuration method of phase angle feedforward parameters for the active power-frequency response model of the phase angle feedforward compensation VSG system. By constructing a three-layer control architecture of "local sensing-neighborhood cooperation-global stability", autonomous parameter matching and oscillation suppression of multiple VSG systems are realized, active power oscillation after disturbance is eliminated, and high-proportion renewable energy power quality regulation resource coordination-autonomy is achieved.

[0024] Specifically, step 1 includes:

[0025] Virtual synchronous generator (VSG) technology simulates the dynamic characteristics of a synchronous generator, providing the system with inertia and damping characteristics. Due to the control characteristics of the VSG, its phase angle is flexible and controllable. Therefore, the difference between the power surge and the steady-state power can be calculated using the power surge, and this difference can be directly compensated to the output phase angle parameter via a proportional feedforward circuit. Because this component directly causes the output phase angle change without going through an inertial circuit, the relationship with the phase angle difference of the other VSGs changes abruptly, thus directly changing the output power of each VSG. If the compensation power of each inverter is equal to the difference between the initial power surge and the steady-state power, and the frequency changes between the inverters are consistent (i.e., the inertial response characteristics are the same), then the phase angle difference between the units remains unchanged, and in terms of power response, the system can directly reach steady state.

[0026] like Figure 1 The diagram shows the active power control block diagram of the phase angle feedforward compensated VSG, where P ref P is the reference value for active power of VSG. E K represents the actual output active power. j K is the inertia coefficient. d ω is the primary frequency modulation coefficient. N θ is the system's rated frequency. v To output the phase signal, Kδ’ The phase angle feedforward compensation coefficient is the power change information fed back to the active power control loop from the power measurement stage. This information, after being processed by the compensation coefficient, is then superimposed onto the output reference phase angle θ. v Above this, the reference phase angle will be fed into the coordinate transformation stage to change the phase of the reference voltage signal (i.e., to make the phase angle of the converter output voltage θ through the PWM stage). v ), where s is the Laplace operator.

[0027] Specifically, step 2 includes:

[0028] like Figure 2 The diagram shows a microgrid topology with n VSG inverters operating in parallel. The n VSG-controlled grid-type inverters, equipped with frequency and voltage regulation capabilities, are filtered by an LC filter, and then connected to the AC bus at the point of common coupling (PCC) via the line impedance to supply power to loads 1 through n. Where R... f1 R f2 R fn These are the 1st, 2nd, and nth VSGs respectively. Figure 2 The filter resistors (VSG1, VSG2, VSGn) L f1 L f2 L fn The filter inductors C for the 1st, 2nd, and nth VSGs are respectively. f1 C f2 C fn These are the filter capacitors for the 1st, 2nd, and nth VSG units, R1, R2, and R3 respectively. n The line resistances L1, L2, and L3 of the lines where the 1st, 2nd, and nth VSGs are located are respectively. n These are the line inductances of the lines where the 1st, 2nd, and nth VSGs are located, respectively.

[0029] based on Figure 2 Given the topology, the active power output of the i-th VSG is:

[0030] (1)

[0031] Among them, P Ei E represents the active power output of the i-th VSG. i and E j The electromotive forces of the i-th and j-th VSGs are δ, respectively. ij Let G be the phase angle difference between the i-th and j-th VSGs. ij and B ij Let be the conductance and susceptance between the i-th and j-th VSGs, respectively, and n be the total number of VSGs.

[0032] For equation (1), after small-signal linearization at the steady-state operating point P0, the change in active power output of the VSG is related to the change in load power and the change in phase angle difference between other VSGs. After linearization, it can be expressed as:

[0033] (2)

[0034] Where, ΔP Ei Let ΔP be the change in active power output of the i-th VSG. L Δδ represents the change in load power. ij W represents the change in phase angle between the i-th VSG and the j-th VSG. ii W ij These are the power linearity coefficient and the phase angle linearity coefficient, respectively. They are constant coefficients generated during the linearization process in the derivation, and are only related to the line topology and line impedance. They can be expressed as:

[0035] (3)

[0036] Among them, G ij0 G at the steady-state operating point P0 ij Conductivity, B ij0 G at the steady-state operating point P0 ij Susceptance, δ ij0 Let δ be the value of the i-th VSG and the j-th VSG at the steady-state operating point P0. ij Phase angle difference, K ij With H ij These are the conductivity values ​​G ij With susceptance value B ij Regarding the change in load power ΔP L The linear coefficients.

[0037] Based on Equation (1), the linear expression for the active power change of a multi-VSG parallel operation system, and Figure 1 The established active power control block diagram for phase-angle feedforward compensated VSGs can be used to construct an active power-frequency response model for an n-unit phase-angle feedforward compensated VSG system. Assuming the system has n VSGs, due to energy conservation, after power compensation for n-1 of the inverters, the uncompensated VSG inverters will automatically bear the remaining deviation power. Therefore, optimal configuration of the compensation coefficients for the n-1 VSGs is required to effectively suppress power oscillations between units.

[0038] like Figure 3 The figure shows the active-frequency response model of a microgrid system with n VSGs connected in parallel, applying phase angle feedforward control. Where W... 11 W 22 W nn The power linearity coefficients W for the 1st, 2nd, and nth VSGs are respectively.12 W 21 W represents the phase angle linearity coefficient between the first and second VSG units. 1n W n1 W represents the phase angle linearity coefficient between the 1st and nth VSGs. 2n W n2 K represents the phase angle linearity coefficient between the 2nd and nth VSGs. J1 K J2 K Jn These are the per-unit values ​​of the inertia coefficients of the 1st, 2nd, and nth VSG units, respectively, and K. D1 K D2 K Dn These are the per-unit values ​​of the primary frequency modulation coefficients for the 1st, 2nd, and nth VSGs, respectively, ΔP E1 ΔP E2 ΔP En These represent the changes in active power output by the 1st, 2nd, and nth VSGs, Δω. v1 , Δω v2 , Δω v3 These are the angular frequency changes of the outputs of the 1st, 2nd, and nth VSGs, respectively. After integration, they represent the output phase changes, K. δ1’ K δ2’ K δn’ Let be the phase angle feedforward compensation coefficients for the 1st, 2nd, and nth VSGs, and s be the Laplace operator.

[0039] like Figure 3 The figure shows the active-frequency control model of the nth VSG in a microgrid system with n VSGs in parallel, after applying phase angle feedforward control. Where W... nn Its power linearity coefficient, W n2 The phase angle linearity coefficient between the 2nd and nth VSGs. W n1 K represents the phase angle linearity coefficient between the 1st and nth VSGs. Jn K Dn Let ΔP be the per-unit value of the inertia coefficient and the primary frequency modulation coefficient of the nth station, respectively. En Let Δω be the change in active power output of the nth VSG. vn The phase angle feedforward compensation coefficient of the nth VSG, after integration, becomes the output phase change. K δ2’ Let be the phase angle feedforward compensation coefficient for the nth VSG, and s be the Laplace operator. When a sudden load change occurs in a microgrid system with n VSGs in parallel, oscillating power will be generated between the VSGs due to the change in phase angle difference, such as... Figure 3The control model shown uses a phase angle feedforward loop to directly compensate the signal difference change to its output phase angle parameter via a proportional feedforward loop, thereby changing the phase angle difference relationship between each VSG in the system, changing the output power of each VSG, and thus eliminating oscillation power.

[0040] Specifically, step 3 includes:

[0041] This step proposes a phase angle feedforward coefficient tuning strategy that integrates dynamic impedance identification and distributed collaborative optimization. By constructing a three-layer control architecture of "local sensing - neighborhood collaboration - global stability," autonomous parameter matching and oscillation suppression of multi-VSG systems are achieved. The specific implementation process is as follows:

[0042] Step 31: Perform dynamic identification of the system's equivalent impedance:

[0043] The local system equivalent impedance of the i-th VSG Defined as:

[0044] (4)

[0045] Where, ΔP Ei Let Δδ be the change in the output active power of the i-th VSG. ij W represents the change in phase angle between the i-th and j-th VSGs. ij The phase angle linearity coefficient defined by equation (1) characterizes the coupling strength of line impedance to power distribution.

[0046] Each VSG operates an independent impedance observer, avoiding reliance on global communication, and employs a sliding window mean filtering technique. Smoothing and filtering are performed to obtain the impedance value. for:

[0047] (5)

[0048] Among them, T w The time window length is 0.1s. t is the time variable, and dτ is the integration variable.

[0049] Step 32: Perform distributed collaborative optimization tuning, including:

[0050] Construct an objective function that includes impedance matching and neighborhood consistency:

[0051] (6)

[0052] Among them, K Ji K Di Let K be the per-unit value of the inertia coefficient and the primary frequency modulation coefficient of the i-th VSG, respectively. δi’ and K δj’Let be the phase angle feedforward compensation coefficients of the i-th and j-th VSGs respectively, λ be the neighborhood cooperative weight coefficient factor, N(i) be the set of physical adjacent units of the i-th VSG, and s be the Laplace operator.

[0053] The distributed alternating direction multiplier method (ADMM) is employed, with each VSG performing iterations independently.

[0054] Local variables are updated to:

[0055] (7)

[0056] The dual variable is updated as follows:

[0057] (8)

[0058] Among them, u ij Let be the dual variable, ρ=1 be the penalty factor, and k be the number of iterations. The convergence condition of the algorithm is the K values ​​of adjacent iterations. δi’ The change is less than 10 -3 argmin represents the set of input values ​​used to find the minimum value of the objective function, and i and j represent the indices of the VSG in the system. Let k be the dual variable and k be the iteration number. The convergence condition of the algorithm is the sum of the k values ​​of adjacent iterations. δi’ The change is less than 10 -3 .

[0059] Meanwhile, to prevent the system's inertial response capability from degrading due to excessively large compensation coefficients, inertial-damping characteristic protection constraints are introduced.

[0060] The compensation cap is defined as follows:

[0061] (9)

[0062] Wherein, α is the inertia retention factor, with a default value of 0.8. When the system frequency change rate is detected to be greater than 10Hz / s, the inertia retention factor is reduced to 0.6 to ensure limited inertial support capability.

[0063] Example:

[0064] based on Figure 2 The topology shown is used to build a simulation model of a microgrid with three VSGs (VSG1, VSG2, VSG3) running in parallel in the simulation software. The simulation parameters are shown in Table 1.

[0065] Table 1

[0066]

[0067] The system experienced a load surge of 0.3 pu (per unit) at 4 seconds. Without phase angle feedforward compensation control, the power and frequency changes of each unit were as follows: Figure 4a As shown, power oscillations occur between the various VSGs in the system, and all exhibit significant overshoot compared to the steady-state power. When the phase angle feedforward compensation control method described in this invention is used, the power response and frequency changes of each VSG are as follows: Figure 4b As shown, after adopting the phase angle feedforward compensation proposed in this invention, the sudden increase in active power at the moment of load change is the steady-state power increment of the VSG, which directly corrects the power deficit caused by the phase angle difference, completely eliminates the active power oscillation in the system after disturbance, and realizes high-proportion renewable energy power quality regulation resource coordination-autonomy. Figure 4a , Figure 4b In this context, PE represents power, PU represents per-unit value, t represents time, and s represents the unit as seconds.

Claims

1. A resource-coordinated autonomous method for regulating power quality with a high proportion of renewable energy, characterized in that, Includes the following steps: Step 1: Construct a single-unit active-frequency control model for a phase-forward VSG; VSG represents a virtual synchronous generator. Step 2: Based on the active-frequency control model of a single phase-forward VSG unit, construct the active-frequency response model of the phase-forward compensated VSG system; Step 3: Derive the optimal configuration method for the phase angle feedforward parameters of the active power-frequency response model of the phase angle feedforward compensated VSG system. By constructing a three-layer control architecture of "local sensing-neighborhood cooperation-global stability", autonomous parameter matching and oscillation suppression of multiple VSG systems are achieved, eliminating active power oscillations after disturbances, and realizing resource coordination and autonomy for high-proportion renewable energy power quality regulation, including: Step 31: Perform dynamic identification of the system equivalent impedance; each VSG runs an impedance observer independently to avoid reliance on global communication, and a sliding window mean filtering technique is used to identify the local system equivalent impedance of the i-th VSG. Smoothing is performed to obtain the filtered impedance value. : （1） Among them, T w dτ is the length of the time window, t is the time variable, and dτ is the integration variable; Step 32: Perform distributed collaborative optimization tuning, including: constructing an objective function that includes impedance matching and neighborhood consistency; each VSG independently performs iterations using the distributed alternating direction multiplier method; updating the dual variables; introducing inertial-damped characteristic protection constraints and defining the compensation upper limit; The constructed objective function, which includes impedance matching and neighborhood consistency, is as follows: （2） Among them, K Ji K Di Let K be the per-unit value of the inertia coefficient and the primary frequency modulation coefficient of the i-th VSG, respectively. δi’ and K δj’ Let be the phase angle feedforward compensation coefficients of the i-th and j-th VSGs respectively, λ be the neighborhood cooperative weight coefficient factor, N(i) be the set of physical adjacent units of the i-th VSG, and s be the Laplace operator.

2. The high-proportion renewable energy power quality regulation resource coordination-autonomy method according to claim 1, characterized in that, Step 1 includes: The dynamic characteristics of a synchronous generator are simulated, and the difference is calculated using power mutation. The difference is then compensated to the output phase angle through a proportional feedforward circuit, and the power is quickly adjusted to form a phase angle feedforward VSG single-unit active-frequency control model.

3. The high-proportion renewable energy power quality regulation resource coordination-autonomy method according to claim 2, characterized in that, Step 2 includes: Construct a linear expression for the active power change in a multi-VSG parallel operation system; After small-signal linearization at the steady-state operating point P0, the change in active power output of the VSG is related to the change in load power and the change in phase angle difference with other VSGs, and is expressed as follows after linearization: （3） Where, ΔP Ei Let ΔP be the change in active power output of the i-th VSG. L Δδ represents the change in load power. ij W represents the change in phase angle between the i-th VSG and the j-th VSG. ii W ij These are the power linearity coefficient and the phase angle linearity coefficient, respectively, and n is the number of VSGs.

4. The high-proportion renewable energy power quality regulation resource coordination-autonomy method according to claim 3, characterized in that, W ii W ij Represented as: （4） Among them, G ij0 G at the steady-state operating point P0 ij Conductivity, B ij0 G at the steady-state operating point P0 ij Susceptance, δ ij0 Let δ be the value of the i-th VSG and the j-th VSG at the steady-state operating point P0. ij Phase angle difference, K ij With H ij The conductivity values ​​G are respectively ij With susceptance value B ij Regarding the change in load power ΔP L The linear coefficients; E i and E j Let be the electromotive forces of the i-th and j-th VSGs, respectively; An active-frequency response model for an n-phase-angle feedforward compensated VSG system is constructed based on the linear expression of active power variation in a multi-VSG parallel operation system.

5. A resource-coordinated autonomous method for high-proportion renewable energy power quality regulation according to claim 4, characterized in that, Step 3 includes: Step 31: Perform dynamic identification of the system's equivalent impedance, including: The local system equivalent impedance of the i-th VSG (t) is defined as: （5）。 6. The high-proportion renewable energy power quality regulation resource coordination-autonomy method according to claim 1, characterized in that, Each VSG independently executes iterations using the distributed alternating direction multiplier method, including: Local variables are updated to: （6） Where argmin represents the set of input values ​​when the objective function is minimized, ρ is the penalty factor, which is 1, and i and j represent the indices of VSGs in the system. Let k be the dual variable and k be the iteration number; the convergence condition is the K values ​​of adjacent iterations. δi’ The change is less than 10 -3 .

7. A resource-coordinated autonomous method for high-proportion renewable energy power quality regulation according to claim 6, characterized in that, The dual variable is updated as follows: （7）。 8. A resource-coordinated autonomous method for high-proportion renewable energy power quality regulation according to claim 7, characterized in that, The compensation cap is defined as follows: （8） Where α is the inertia retention factor.

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