Synchronverter based photovoltaic inverter

Kustanovich, Zeev

doi:10.1109/icsee.2018.8646184

Cited by 9 publications

(5 citation statements)

References 9 publications

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“…In (15), K > 0 is a large constant. The valueQ represents a compromise between tracking the reference reactive power Q set and tracking the reference value v set for the amplitude of v. Tracking v set makes sense only if the inverter is connected to the infinite bus through a line impedance, and not directly, as in our model.…”

Section: Modelling the Grid-connected Synchronverter With Measurement Errorsmentioning

confidence: 99%

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The Sensitivity of Grid-Connected Synchronverters With Respect to Measurement Errors

Kustanovich¹,

Reißner

Shivratri

2021

IEEE Access

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The synchronverter algorithm is a way to control a switched mode power converter that connects a DC energy source to the AC power grid. The main features of this algorithm are frequency and voltage droops as well as synthetic inertia, so that the inverter resembles a synchronous generator (SG). Many versions of this algorithm have been proposed and tested, but all share the same "basic control algorithm", which is based on the equations of a SG. We analyze the sensitivity of the output currents of a synchronverter, with respect to the measurement errors. We show that some of the sensitivity functions exhibit high gains at the relevant frequencies, leading to distorted grid currents, which makes the use of this inverter control algorithm problematic. We then do a similar analysis assuming that we have controlled current sources available at the grid output of the converter, that we control using virtual currents generated in the algorithm. The virtual currents are flowing through virtual output inductors, that we can choose to be significantly larger than the actual output inductors. We show that using the current sources reduces the sensitivity considerably, thus indicating a better approach to synchronverter design.

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Section: Modelling the Grid-connected Synchronverter With Measurement Errorsmentioning

confidence: 99%

“…Example 1: We use the parameters of a synchronverter designed to supply a nominal active power of 9 kW to a grid with frequency ω g = 100π rad/sec (50Hz) and line voltage V = 230 √ 3Volts. This is based on a real inverter that we have built, see [15]. The parameters are:…”

Section: Small Signal Analysismentioning

confidence: 99%

The Sensitivity of Grid-Connected Synchronverters With Respect to Measurement Errors

Kustanovich¹,

Reißner

Shivratri

2021

IEEE Access

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“…In this section, we use two examples from the synchronverter literature to illustrate our theoretical derivations: Example VI-A is taken from [12], and Example VI-B from [18]. The focus is the stability analysis of the fourth order model (13), and of the fifth order model (18), for varying values of P set and Q set .…”

Section: Numerical Examplesmentioning

confidence: 99%

“…We use the parameters of a synchronverter designed to supply a nominal active power of 9 kW to a grid with frequency ω g = 100π rad/sec (50 Hz) and line voltage V = 230 √ 3 Volts. This is based on a real inverter that we have built, see [12]. The parameters are: From Theorem 4.5 we know that there are four equilibrium points.…”

Section: A Low-voltage Synchronvertermentioning

confidence: 99%

The equilibrium points and stability of grid-connected synchronverters

Lorenzetti¹,

Kustanovich²,

Shivratri³

et al. 2021

Preprint

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Virtual synchronous machines are inverters with a control algorithm that causes them to behave towards the power grid like synchronous generators. A popular way to realize such inverters are synchronverters. Their control algorithm has evolved over time, but all the different formulations in the literature share the same "basic control algorithm". We investigate the equilibrium points and the stability of a synchronverter described by this basic algorithm, when connected to an infinite bus. We formulate a fifth order model for a grid-connected synchronverter and derive a necessary and sufficient condition for the existence of equilibrium points. We show that the set of equilibrium points with positive field current is a two-dimensional manifold that can be parametrized by the corresponding pair (P, Q), where P is the active power and Q is the reactive power. This parametrization has several surprizing geometric properties, for instance, the prime mover torque, the power angle and the field current can be seen directly as distances or angles in the (P, Q) plane. In addition, the stable equilibrium points correspond to a subset of a certain angular sector in the (P, Q) plane. Thus, we can predict the stable operating range of a synchronverter from its parameters and from the grid voltage and frequency. Our stability result is based on the intrinsic two time scales property of the system, using tools from singular perturbation theory. We illustrate our theoretical results with two numerical examples.

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“…In Section V we report our simulations, that show the influence of the VF torques on the second order SG models and compare the evolution of the grounded rotor angles for the same scenarios of the grid. In addition, a more realistic simulation based on the synchronverter detailed in [20,21] is performed on the same grid, also employing a more detailed dynamic model for the transmission lines and resistive loads. Finally we investigate the impact of the communications time delays on the stabilizing effect of the VF.…”

Section: Introductionmentioning

confidence: 99%

A Stability Result for Network Reduced Power Systems Using Virtual Friction and Inertia

Reißner

Yin

Weiss

2022

IEEE Trans. Smart Grid

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We prove that virtual friction can stabilize a power grid containing several virtual synchronous machines (VSMs), connecting line impedances and loads. Virtual friction is a torque added to the swing equation of each VSM, proportional to the deviation of its frequency from the overall center of inertia (COI) frequency. Our analysis is based on the network reduced power system (NRPS) model. We support our results with simulations for a two-area network of four VSMs, looking at the transients induced by a change of tie-line impedance and an asymmetric load change. We compare the results for the NRPS model with the corresponding results using detailed models of synchronverters and line impedances. We find that virtual friction has a strong stabilizing effect both for the NRPS model and for the detailed model. Furthermore we show simulation results on the influence of time delays in the communication between the inverters. This communication is used to compute the COI frequency. It turns out that communication delays of less than 100ms have practically no effect on the overall system.

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Synchronverter based photovoltaic inverter

Cited by 9 publications

References 9 publications

The Sensitivity of Grid-Connected Synchronverters With Respect to Measurement Errors

The Sensitivity of Grid-Connected Synchronverters With Respect to Measurement Errors

The equilibrium points and stability of grid-connected synchronverters

A Stability Result for Network Reduced Power Systems Using Virtual Friction and Inertia

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