An inertia adaptive control method of a virtual synchronous generator (VSG) considering transient damping compensation

Abstract

The application discloses an inertia adaptive control method of a virtual synchronous generator (VSG) considering transient damping compensation, introduces a power differential feedforward and a power angle increment feedforward double-path transient damping compensation branch in an active control loop of the VSG, and provides additional damping torque; a Luenberger filter is designed to reconstruct a power differential signal, suppress noise and avoid phase lag; an inertia adaptive law is constructed to adjust virtual inertia in real time according to a frequency deviation and a change rate, so that time-sharing optimization of large inertia to suppress frequency disturbance and small inertia to accelerate frequency recovery is realized; the transient damping compensation and the inertia adaptation are cooperated, the former dominates the suppression of the frequency amplitude in the first swing stage, and the latter adjusts the inertia size on line in the whole transient process. The application enhances transient damping without changing the steady-state droop characteristic, simultaneously optimizes dynamic response on line through inertia adaptation, and takes into account disturbance suppression capacity and recovery rapidity.

Description

Technical Field

[0001] This invention belongs to the field of new energy grid-connected control technology. Specifically, it relates to an inertia adaptive control method considering a transient damping compensated virtual synchronous generator (VSG). Background Technology

[0002] Voltage source converters (VRBs) are key interface devices for renewable energy grid integration. Their large-scale integration leads to a significant decrease in the equivalent inertia and damping level of the power system, posing a severe challenge to frequency stability. Grid-connected converters, especially virtual synchronous generator (VSG) technology, have become one of the mainstream solutions because they can simulate the external characteristics of synchronous generators and provide inertial and damping support for the system.

[0003] However, VSGs are prone to oscillations in active power and frequency during power command abrupt changes or grid disturbances, which can seriously threaten equipment safety and system stability. Fixed-parameter VSG control struggles to meet dynamic demands under different operating conditions: insufficient inertia leads to inadequate frequency support and excessively high rate of change; excessive inertia causes power overshoot and prolonged oscillations. Increasing the damping coefficient can suppress oscillations, but it alters the steady-state droop characteristics and is subject to grid primary frequency regulation specifications.

[0004] To address the aforementioned issues, existing research primarily employs two methods: first, VSG inertia adaptive control, which adjusts the virtual inertia in real time based on the system's frequency state to improve dynamic response performance. However, this method suffers from decreased system damping ratio and slow oscillation decay under high inertia conditions. Second, transient damping compensation, which introduces a compensation term into the forward path to enhance damping and suppress power oscillations. However, in this method, the VSG inertia remains a fixed value, unable to be flexibly adjusted according to the system state, and the compensation stage is prone to inverse power overshoot. Since inertia determines response speed and frequency support strength, while damping determines oscillation suppression capability and steady-state convergence characteristics, the two methods are physically complementary. However, existing technologies have long used them independently, failing to form a unified and coordinated framework. Furthermore, control parameter tuning often relies on empirical trial and error, making it difficult to establish a correlation between parameter changes and dynamic response. Summary of the Invention

[0005] To address the aforementioned shortcomings in existing technologies, this invention provides an inertia adaptive control method for a virtual synchronous generator (VSG) that takes into account transient damping compensation. This method can significantly improve the frequency dynamic response under small disturbance conditions, achieving coordinated operation of transient damping-dominated suppression of the first sway and online inertia optimization throughout the entire process, thus balancing disturbance suppression capability and rapid recovery.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows: An inertia adaptive control method considering a transient damped compensated virtual synchronous generator (VSG) includes the following steps: S1. Establish the VSG active power loop control model, collect the voltage and current at the grid connection point to calculate the active power feedback value, process the deviation between the active power reference value and the feedback value through the VSG active power control equation to generate the reference angular frequency and reference phase angle, and then proceed to S2. S2. Construct a dual-path transient damping compensation branch with power differential feedforward and power angle increment feedforward, and superimpose the two compensation quantities into the damping term of the VSG active power control equation through feedforward to provide additional damping torque during the transient process and achieve decoupling between dynamic characteristics and steady-state droop characteristics. S3. Design a Luenberger differential noise filter, construct a state observer with active power and its derivative as state variables, reconstruct the power differential signal, and replace the differential signal in step S2 to suppress measurement noise amplification and not introduce phase lag. S4. Based on the transient damping compensation VSG formed by S2 and S3, an adaptive inertia law is constructed. The virtual inertia is corrected in real time according to the frequency deviation and its rate of change, realizing the time-division collaborative optimization of large inertia suppressing frequency disturbances and small inertia accelerating frequency recovery. S5. The transient damping compensation introduced in step S2 is coordinated with the inertia adaptive law constructed in step S4. The transient damping compensation dominates the suppression of frequency amplitude during the initial swing phase, while the inertia adaptive law adjusts the magnitude of inertia online according to the frequency state throughout the transient process.

[0007] Furthermore, in step S2, the design of the transient damping compensation VSG is based on the small-signal model of the classical VSG, and the change in active power is obtained through the differential element. F 1. Sample the power angle increment through a time delay element. F 2. At this point, the rotor dynamic equation in S1 can be expressed as: , in, D p The damping coefficient is... J For virtual inertia, ω VSG angular frequency, ω n The rated angular frequency, P 0 is the active power reference. P e It is the actual active power.

[0008] First compensation amount of power differential feedforward branch F 1 satisfies: , in, K p This is the power damping feedforward coefficient. T Sampling time.

[0009] Second compensation amount of the feedforward branch for power angle increment F 2. Satisfies: , in, K δ is the power angle damping feedforward coefficient.

[0010] Equivalent damping during system disturbance transient process D eq The size is: , Furthermore, in step S3, the Luenberger differential noise filter is discretized and modeled as follows: , In S4, the adaptive inertia law has two significant characteristics: natural boundedness and speed. Its expression is: , J 0 represents constant inertia, 2 represents constant inertia. K J arctan(Δ ω d ω / d t ) / π is the adaptive compensation inertia. K J This is the positive inertia compensation coefficient, used to adjust the dynamic response speed at high frequencies. The total moment of inertia is determined based on the relative angular velocity Δ. ω and its rate of change d ω / d t Real-time correction. In steady state, the second term of the adaptive compensation inertia is 0, and the total inertia equals... J 0.

[0011] Furthermore, in S5, the influence of key parameters on pole distribution and damping ratio is studied, and a general criterion for parameter design is established.

[0012] The above-mentioned technical solution of the present invention has the following beneficial effects: 1. This invention introduces a dual-path transient damping compensation feedforward branch of power derivative and power angle increment into the VSG active control loop, which compensates for transient damping without changing the steady-state droop characteristics, thereby achieving decoupling between dynamic characteristics and steady-state droop characteristics and overcoming the fundamental defect of lack of dynamic adjustment freedom in classical VSG control. 2. This invention designs a Luenberger differential noise filter to reconstruct the power differential signal using a state observation method, effectively suppressing measurement noise amplification and avoiding phase lag. This solves the engineering problem of system performance degradation caused by noise interference in the power differential feedforward branch in actual digital control. 3. Based on transient damping compensation VSG, this invention constructs an inertia adaptive law with natural boundedness and speed. The inertia is dynamically adjusted according to the frequency state to achieve time-division synergistic optimization of suppressing frequency disturbances with large inertia and accelerating frequency recovery with small inertia. It forms a synergistic cooperation mechanism with transient damping compensation to suppress the first swing and optimize the inertia online throughout the entire process. Attached Figure Description

[0013] To more clearly illustrate the embodiments and technical solutions of the present invention, the accompanying drawings used will be briefly described below.

[0014] Figure 1 A flowchart illustrating the steps of an adaptive inertia control method for a virtual synchronous generator (VSG) that takes into account transient damping compensation.

[0015] Figure 2 This is a typical circuit diagram of a grid-connected system for a grid-type converter.

[0016] Figure 3 This is a control structure diagram for a grid-connected system of a grid-type converter.

[0017] Figure 4 This is a diagram of the active power loop control architecture of TDC-VSG.

[0018] Figure 5 Diagram of the improved TDC-VSG active loop control architecture with inertia adaptive control.

[0019] Figure 6 Step response with frequency-controlled inertia J A graph showing the variation of a (fixed value).

[0020] Figure 7 This is a schematic diagram of the adaptive virtual inertia method.

[0021] Figure 8 To work in VSG mode, J Experimental waveform diagram when =0.12 (small inertia).

[0022] Figure 9 To work in TDC-VSG mode, J Experimental waveform diagram when =0.12 (small inertia).

[0023] Figure 10 To work in TDC-VSG mode, J Experimental waveform diagram when =0.6 (large inertia).

[0024] Figure 11 To work in TDC-VSG mode, J Experimental waveforms for the proposed (adaptive) method. Detailed Implementation

[0025] To make the objectives, technical solutions, and advantages of the present invention clearer, the technical solutions of the present invention will be further described below in conjunction with the accompanying drawings and tables. It should be understood that the description of the embodiments of the present invention herein is not intended to limit the scope of protection of the present invention.

[0026] This invention provides an inertia adaptive control method considering a transient damped compensated virtual synchronous generator (VSG). Figure 1 This is a flowchart illustrating the steps of the inertia adaptive control method of the present invention, which takes into account transient damping compensated virtual synchronous generators (VSGs), including the following steps: S1. Establish the VSG active power loop control model, collect the voltage and current at the grid connection point to calculate the active power feedback value, process the deviation between the active power reference value and the feedback value through the VSG active power control equation to generate the reference angular frequency and reference phase angle, and then proceed to S2. S2. Construct a dual-path transient damping compensation branch with power differential feedforward and power angle increment feedforward, and superimpose the two compensation quantities into the damping term of the VSG active power control equation through feedforward to provide additional damping torque during the transient process and achieve decoupling between dynamic characteristics and steady-state droop characteristics. S3. Design a Luenberger differential noise filter, construct a state observer with active power and its derivative as state variables, reconstruct the power differential signal, and replace the differential signal in step S2 to suppress measurement noise amplification and not introduce phase lag. S4. Based on the transient damping compensation VSG formed by S2 and S3, an adaptive inertia law is constructed. The virtual inertia is corrected in real time according to the frequency deviation and its rate of change, realizing the time-division collaborative optimization of large inertia suppressing frequency disturbances and small inertia accelerating frequency recovery. S5. The transient damping compensation introduced in step S2 is coordinated with the inertia adaptive law constructed in step S4. The transient damping compensation dominates the suppression of frequency amplitude during the initial swing phase, while the inertia adaptive law adjusts the magnitude of inertia online according to the frequency state throughout the transient process.

[0027] Figure 2 This demonstrates a typical circuit structure for a grid-connected converter system. The converter utilizes a filter inductor... L f Filter capacitor C f At the point of common coupling (PCC), the external power grid uses a constant voltage source connected in series with the grid inductor. L g The system measures electrical quantities including the filter inductor current. I abc Common coupling point voltage U gabc and currentI gabc .

[0028] Figure 3 This describes the control structure for a grid-connected converter system. The active power loop utilizes a VSG to generate a reference phase angle. θ The rotor motion equation of the simulated synchronous generator is: , in, D p The damping coefficient is... J For virtual inertia, ω VSG angular frequency, ω n The rated angular frequency, P 0 is the active power reference. P e It is the actual active power.

[0029] The reactive power ring adopts a PI type. QU Droop, generating voltage reference E m .

[0030] When the VSG is operating normally, its output active power expression is: , in, X g For grid-side reactance, V e It is the effective value of the grid voltage. δ = δ e - δ g It is represented as the work angle.

[0031] The active power-active reference transfer function is obtained as follows: , in, K s =3 E m V e cos δ 0 / X g The natural oscillation angular frequency can be obtained from this. ω 1 and damping ratio ξ 1 is: , The natural oscillation angular frequency and damping ratio together determine the system's frequency dynamic response characteristics. Virtual inertia. JSimultaneously affecting the natural oscillation angular frequency and damping ratio, only adjusting... J It cannot meet the system's adjustment requirements. Increase... J It can reduce the natural oscillation angular frequency and bandwidth, but it will lead to a slower response, a decrease in damping ratio, and a greater likelihood of active power oscillation. Increasing D p While increasing the damping ratio without affecting the natural oscillation angular frequency can effectively suppress oscillations, it alters the steady-state droop characteristics, and its value is constrained by the primary frequency regulation specifications of the power grid. Therefore, classical VSG control suffers from the fundamental problem of a lack of dynamic adjustment freedom.

[0032] Figure 4 The active power loop control architecture is TDC-VSG. To address the aforementioned lack of dynamic adjustment degrees of freedom, a dual-path transient damping compensation (TDC) feedforward branch, incorporating power derivative and power angle increment, is introduced into the VSG active power control loop. The design of the transient damping compensation VSG is based on the classic VSG small-signal model, using a derivative element to capture the change in active power. F 1. Sample the power angle increment through a time delay element. F 2. The rotor dynamic equation can be expressed as: , in, D p The damping coefficient is... J For virtual inertia, ω VSG angular frequency, ω n The rated angular frequency, P 0 is the active power reference. P e It is the actual active power.

[0033] First compensation amount of power differential feedforward branch F 1 satisfies: , in, K p This is the power damping feedforward coefficient. T Sampling time.

[0034] Second compensation amount of the feedforward branch for power angle increment F 2. Satisfies: , in, K δ is the power angle damping feedforward coefficient.

[0035] Equivalent damping during system disturbance transient process D eq The size is: , The natural oscillation angular frequency of TDC-VSG ω 2 and damping ratio ξ 2 is: , At this point, the TDC-VSG active power-active reference transfer function is: , The TDC-VSG angular frequency-active reference transfer function is: , Comparing the natural oscillation angular frequency and damping ratio of TDC-VSG and classical VSG, the natural oscillation angular frequency is the same for both, indicating that the system's response speed and bandwidth are not affected by the introduction of feedforward control. However, without changing the steady-state droop characteristics, TDC-VSG supports the transient process through a transient damping feedforward term, introducing an additional damping contribution, thereby decoupling the dynamic and steady-state characteristics and improving the system's dynamic characteristics.

[0036] Figure 5 This study presents an improved TDC-VSG active power loop control architecture with inertia adaptive control. The main research work is divided into two parts: suppressing active power differential noise without introducing phase lag and proposing an inertia-based adaptive control mechanism. J Parameter adaptive control method.

[0037] The state variables are selected as active power and its derivative, i.e. x 1= P e , x 1=d P e / d t Establish a continuous domain state-space model and input... u = P 0, yielding the coefficient matrix: , In engineering, considering that the filter itself has error correction capabilities, K s / Jω n All can be directly set to zero without affecting the convergence of the state estimation. The forward Euler method is used to discretize the above equation after setting it to zero: , The discretization model of the Luenberger differential noise filter is as follows: , In the formula, the output quantity y = Pe, and the output matrix C = [1, 0]. The gain matrix L = [l1, l2] provides closed-loop correction capability and an estimate of the active power. P pre Through measured values P e Gain l 1. Real-time correction, power differential estimate d P pre / d t Then through gain l 2. Obtained indirectly.

[0038] Figure 6 Step response with frequency-controlled inertia J The change of (fixed value). The time-domain expression of the TDC-VSG frequency step response is: , Calculate the overshoot σ % and adjustment time t s for: , along with J As the frequency increases, the overshoot will decrease, and the settling time will increase.

[0039] Figure 7 This relates to the principle of the adaptive virtual inertia method. For example... Figure 7 As shown in Table 1, when the frequency deviates from the nominal reference, a slower system response is desired, and the inertia should be increased; when the frequency returns to the rated frequency, an accelerated dynamic process is desired, and the inertia should be decreased. Therefore, a simple and unified adaptive virtual inertia method is constructed: .

[0040] Table 1 Design principles of virtual inertia under different operating conditions The proposed adaptive law has two significant characteristics: (1) Naturally bounded: Considering the range of the arctan function and the virtual inertia J Restricted to [ J 0- K J , J 0+ K J Within this range, the value will not increase or decrease indefinitely due to extreme disturbances, thus ensuring the stability of the system.

[0041] (2) Speed: When the system is disturbed, Δ ω d ω / d tWith a sudden increase, the arctan function saturates rapidly, and the inertia switches to the target value in a very short time, satisfying the requirement of speed in transient processes.

[0042] Figure 8 To work in VSG mode, J The experimental waveforms at a power step rate of 0.12 (small inertia) are presented, showing the dynamic response waveforms of the classical VSG control under power step increase and decrease conditions. Under the increasing condition, the maximum frequency disturbance reaches 0.033 Hz, with a settling time of 625 ms; under the decreasing condition, the maximum frequency disturbance is approximately 0.031 Hz, with a settling time of approximately 565 ms. The results indicate that the system's inertial support capability is insufficient, the frequency transient deviation is large, and the recovery process is slow.

[0043] Figure 9 To work in TDC-VSG mode, J The experimental waveform at 0.12 (small inertia) shows the dynamic response waveform after transient damping enhancement. Compared to the VSG mode, the maximum frequency disturbance in the rising condition is reduced to 0.025Hz, and the settling time is shortened to 275ms; the maximum frequency disturbance in the falling condition is reduced to 0.024Hz, and the settling time is shortened to 252ms. This indicates that the improved TDC-VSG effectively suppresses frequency transient deviation and accelerates the frequency recovery process by introducing transient damping feedforward. However, since it does not change the inertia, its ability to suppress the maximum frequency disturbance is limited.

[0044] Figure 10 To work in TDC-VSG mode, J The experimental waveform diagram is shown when the inertia is 0.6 (large inertia). J The dynamic response waveform is increased to 0.6. Under the power step increase condition, the maximum frequency disturbance further decreases to 0.015Hz, but the settling time increases to 890ms; under the power step decrease condition, the maximum frequency disturbance is approximately 0.017Hz, and the settling time is approximately 890ms. The results show that increasing the inertia can effectively suppress transient frequency disturbances, but the frequency recovery process slows down, delaying the speed at which the frequency returns to its rated value.

[0045] Figure 11 To work in TDC-VSG mode, J The experimental waveforms of the proposed method (adaptive) are shown, representing the proposed inertia. J The dynamic response waveform of the adaptive control strategy is shown. Under the power step increase condition, the maximum frequency disturbance is approximately 0.016 Hz, and the settling time is significantly reduced to 320 ms; under the power step decrease condition, the maximum frequency disturbance is approximately 0.016 Hz, and the settling time is approximately 335 ms. The proposed adaptive control strategy significantly reduces the settling time while maintaining the ability to suppress large inertia frequency disturbances.

[0046] Table 2 summarizes the comparison results of the four control performances. (Comparison) Figure 8 and Figure 9 Without changing the moment of inertia, transient damping reduces the maximum frequency disturbance by approximately 24% and shortens the settling time by approximately 56%, indicating that transient damping feedforward has a significant effect on improving the frequency dynamic response; compared to Figure 9 and Figure 10 Inertia J Increasing the inertia from 0.12 to 0.6 reduced the maximum frequency disturbance by approximately 40%, but significantly prolonged the settling time, verifying the findings regarding inertia. J Theoretical analysis of frequency dynamic response; comparison Figure 10 and Figure 11 The proposed adaptive control strategy is comparable to the fixed large inertia condition in terms of maximum frequency disturbance, but the settling time is reduced by approximately 63%. By adjusting the inertia online, it achieves time-sharing collaborative optimization of suppressing frequency disturbances with large inertia and accelerating frequency recovery with small inertia. (Comparison) Figure 11 and Figure 8 Compared with the classic VSG, the proposed strategy reduces the maximum frequency disturbance by about 52% and shortens the settling time by about 49%, indicating that the proposed method significantly enhances the ability to suppress transient frequency disturbances and optimizes dynamic performance without sacrificing rapid frequency recovery.

[0047] Table 2 Design principles of virtual inertia under different operating conditions As verified by the above embodiments, the inertia adaptive control method for a virtual synchronous generator (VSG) considering transient damping compensation proposed in this invention possesses practical feasibility and reliable effectiveness. This method achieves time-sharing collaborative optimization of suppressing frequency disturbances with large inertia and accelerating frequency recovery with small inertia, forming a collaborative mechanism with transient damping compensation that dominates the suppression of initial sway and optimizes inertia online throughout the entire process. Based on this, the inertia adaptive control method for a virtual synchronous generator (VSG) considering transient damping compensation described in this invention effectively solves the problems of poor dynamic response and easy frequency oscillation under small disturbance conditions.

[0048] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. An inertia adaptive control method considering a transient damped compensated virtual synchronous generator (VSG), comprising the following steps, characterized in that, Includes the following steps: S1. Establish the VSG active power loop control model, collect the voltage and current at the grid connection point to calculate the active power feedback value, and process the deviation between the active power reference value and the feedback value through the VSG active power control equation to generate the reference angular frequency and reference phase angle. S2. Construct a dual-path transient damping compensation branch with power differential feedforward and power angle increment feedforward, and superimpose the two compensation quantities into the damping term of the VSG active power control equation through feedforward to provide additional damping torque during the transient process and achieve decoupling between dynamic characteristics and steady-state droop characteristics. S3. Design a Luenberger differential noise filter, construct a state observer with active power and its derivative as state variables, reconstruct the power differential signal, and replace the differential signal in step S2 to suppress measurement noise amplification and not introduce phase lag. S4. Based on the transient damping compensation VSG formed by S2 and S3, an adaptive inertia law is constructed. The virtual inertia is corrected in real time according to the frequency deviation and its rate of change, realizing the time-division collaborative optimization of large inertia suppressing frequency disturbances and small inertia accelerating frequency recovery. S5. The transient damping compensation introduced in step S2 is coordinated with the inertia adaptive law constructed in step S4. The transient damping compensation dominates the suppression of frequency amplitude during the initial swing phase, while the inertia adaptive law adjusts the magnitude of inertia online according to the frequency state throughout the transient process.

2. The method according to claim 1, characterized in that: In step S2, the design of the transient damping compensation VSG is based on the small-signal model of the classical VSG, and the change in active power is obtained through the differential element. F 1. Sample the power angle increment through a time delay element. F 2. At this point, the rotor dynamic equation in S1 can be expressed as: ， in, D p The damping coefficient is... J For virtual inertia, ω VSG angular frequency, ω n The rated angular frequency, P 0 is the active power reference. P e It is the actual active power.

3. The method according to claim 2, characterized in that: The transient damping compensation branch includes a power differential feedforward branch and a power angle increment feedforward branch. First compensation amount of the power differential feedforward branch F 1 satisfies: ， in, K p This is the power damping feedforward coefficient. T Sampling time, Second compensation amount of the feedforward branch for power angle increment F 2. Satisfies: ， in, K δ The power angle damping feedforward coefficient is... Equivalent damping during system disturbance transient process D eq The size is: ， By compensating for transient damping without altering the steady-state droop characteristics, the dynamic characteristics and steady-state droop characteristics are decoupled, overcoming the fundamental defect of the lack of dynamic adjustment degrees of freedom in classical VSG control.

4. The method according to claim 3, characterized in that: The transfer function of the time-delay element is: ， Where T is the sampling time.

5. The method according to claim 1, characterized in that: In step S3, the Luenberger differential noise filter is discretized and modeled as follows: 。 6. The method according to claim 1, characterized in that: In step S4, the inertia adaptive law has two significant characteristics: natural boundedness and speed. Its expression is: ， J 0 represents constant inertia, 2 represents constant inertia. K J arctan(Δ ω d ω / d t ) / π is the adaptive compensation inertia. K J This is the positive inertia compensation coefficient, used to adjust the frequency dynamic response speed. The total moment of inertia is based on the relative angular velocity Δ. ω and its rate of change d ω / d t Real-time correction: In steady state, the second term of the adaptive compensation inertia is 0, and the total inertia equals... J 0.

7. The method according to claim 6, characterized in that: The inertia adaptive law possesses inherent boundedness and speed: (1) Naturally bounded: Considering the range of the arctan function and the virtual inertia J Restricted to [ J 0- K J , J 0+ K J Within this range, the value will not increase or decrease indefinitely due to extreme disturbances, thus ensuring the stability of the system. (2) Speed: When the system is disturbed, Δ ω d ω / d t With a sudden increase, the arctan function saturates rapidly, and the inertia switches to the target value in a very short time, satisfying the requirement of speed in transient processes.

8. The method according to claim 1, characterized in that: The transient damping compensation branch independently increases the damping ratio without changing the natural oscillation angular frequency of the system, while the inertia adaptive law adjusts the magnitude of the inertia online according to the frequency state. The two act on the initial swing stage and the entire transient process, respectively, to achieve coordinated control by which transient damping dominates the suppression of the initial swing and inertia is optimized online throughout the entire process.

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