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See detailTopology and Parameter Estimation in Power Systems Though Inverter Based Broadband Stimulations
Neshvad, Surena UL

Doctoral thesis (2016)

During the last decade, a substantial growth in renewable, distributed energy production has been observed in industrial countries. This phenomenon, coupled with the adoption of open energy markets has ... [more ▼]

During the last decade, a substantial growth in renewable, distributed energy production has been observed in industrial countries. This phenomenon, coupled with the adoption of open energy markets has signi cantly complicated the power ows on the distribution network, requiring advanced and intelligent system monitoring in order to optimize the e ciency, quality and reliability of the system. This thesis proposes a solution several power network challenges encountered with increasing Distributed Generation (DG) penetration. The three problems that are addressed are islanding detection, online transmission line parameter identi cation and system topology identi cation. These tasks are performed by requesting the DGs to provide ancillary services to the network operator. A novel and intelligent method has been proposed for reprogramming the DGs Pulse Width Modulator, requesting each DG to inject a uniquely coded Pseudo-Random Binary Sequence along with the fundamental. Islanding detection is obtained by measuring the equivalent Thevenin impedance at the inverters Point of Common Coupling, while system characterization is obtained by measuring the induced current frequencies at various locations in the grid. To process and evaluate the measured signals, a novelWeighed Least-Squares aggregation method is developed, through which measurements are combined and correlated in order to obtain an accurate snapshot of the power network parameters. [less ▲]

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See detailTopology and Parameter Estimation in Power Systems through Inverter Based Broadband Stimulations
Neshvad, Surena UL; Margossian, Harag UL; Sachau, Jürgen UL

in IET Generation, Transmission & Distribution (2016)

An increasing number of inverter based power generators have been connected to the distribution network in recent years. This phenomenon, coupled with the adoption of open energy markets has significantly ... [more ▼]

An increasing number of inverter based power generators have been connected to the distribution network in recent years. This phenomenon, coupled with the adoption of open energy markets has significantly complicated the powerflows on the power network, requiring advanced and intelligent parameter knowledge to optimize the efficiency, quality and reliability of the system. This paper describes a method for identifying parameters associated with the power system model. In particular, the proposed algorithm in this paper addresses the line parameter and topology identification task in the scope of state estimation. The goal is to reduce the a priori knowledge for state estimation, and to obtain online information on the power system network. The proposed parameter estimation method relies on injected stimulations in the network. Broadband stimulation signals are injected from distributed generators and their effects measured at various locations in the grid. To process and evaluate this data, a novel aggregation method based on weighed least-squares will be proposed in this paper. It combines and correlates various measurements in order to obtain an accurate snapshot of the power network parameters. In order to test its capabilities, the performance of this algorithm is evaluated on a small-scale test system. [less ▲]

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See detailVerification and Implementation of Pseudo-Random-Binary-Sequences for Online Determination of Grid Impedance Spectrum
Tewari, Udit; Neshvad, Surena UL; Sachau, Jürgen UL

in The Renewable Energy & Power Quality Journal (2015, March 25)

The number of inverter based distributed power generators connected to the power network has rapidly grown in recent years. The consequence of this phenomenon is an increasingly complex distribution grid ... [more ▼]

The number of inverter based distributed power generators connected to the power network has rapidly grown in recent years. The consequence of this phenomenon is an increasingly complex distribution grid, requiring advanced and intelligent monitoring and observation tools in order to guarantee satisfactory power quality and reliability. This paper describes a novel power line impedance estimation method, implementing an innovative technique based on modifications of the Pulse Width Modulator’s pulse pattern on the inverters, in order to generate Pseudo-Random Binary Sequence based pilot signals. The stimuli are generated at different locations in the distribution grid, and detected at the transformer sub-station through cross correlation between the received distorted signal and the sequence, the parameters of the propagation channel can be estimated. Simulations in typical grid situations verify that the proposed algorithm is robust to a realistic environment and would [less ▲]

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See detailWideband Identification of Power Network Parameters Using Pseudo-Random Binary Sequences on Power Inverters
Neshvad, Surena UL; Chatzinotas, Symeon UL; Sachau, Jürgen UL

in IEEE Transactions on Smart Grid (2015)

Due to the push for renewable energy in the last decades, European countries have witnessed an exponential growth of Distributed Generation (DG) on the Medium Voltage (MV) network. An increasingly large ... [more ▼]

Due to the push for renewable energy in the last decades, European countries have witnessed an exponential growth of Distributed Generation (DG) on the Medium Voltage (MV) network. An increasingly large portion of the electricity demand is fed in through the distribution grid, whose good health and operational status will be important for guaranteeing grid stability. In Luxembourg, the distribution network is sparsely monitored and controlled, thus instabilities arising due to line overvoltage or DG malfunctioning are not rapidly detected and resolved. This research discusses a novel and low infrastructure methodology for online monitoring of the distribution grid. Such a tool will be increasingly necessary in order to guarantee the stability, reliability and security of the power network, as a larger and larger portion of the energy demand will be satisfied by DG in future years. In this research, advanced system identification techniques utilized in communications, such as Pseudo-Random Binary Sequences, Successive Interference Cancellation are applied to estimate the transfer function of power network propagation paths. The developed method proposes an online monitoring tool that computes grid parameters in real time during operation, without extensive infrastructure addition, by utilizing the PWM based inverters on the grid for active system identification. [less ▲]

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See detailDistribution Grid Monitoring through Pilot Injection and Successive Interference Cancellation
Neshvad, Surena UL; Chatzinotas, Symeon UL; Sachau, Jürgen UL

in IAEE Conference Proceedings (2014)

Due to the push for renewable energy in the last decades, European countries have witnessed an exponential growth of Distributed Generation (DG) on the Medium Voltage (MV) network. An increasingly large ... [more ▼]

Due to the push for renewable energy in the last decades, European countries have witnessed an exponential growth of Distributed Generation (DG) on the Medium Voltage (MV) network. An increasingly large portion of the electricity demand is fed in through the distribution grid, whose good health and operational status will be important for guaranteeing grid stability. In Luxembourg, the distribution network is sparsely monitored and controlled, thus instabilities arising due to line overvoltage or DG malfunctioning are not rapidly detected and resolved. This research discusses a novel and low infrastructure methodology for online monitoring of the distribution grid. Such a tool will be increasingly necessary in order to guarantee the stability, reliability and security of the power network, as a larger and larger portion of the energy demand will be satisfied by DG in future years. In this research, advanced system identification techniques utilized in communications, such as Pseudo-Random Binary Sequences, Successive Interference Cancellation are applied to estimate the transfer function of power network propagation paths. The developed method proposes an online monitoring tool that computes grid parameters in real time during operation, without extensive infrastructure addition, by utilizing the PWM based inverters on the grid for active system identification. [less ▲]

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See detailOnline Determination of Grid Impedance Spectrum through Pseudo-Random Excitation of a Pulse Width Modulator
Neshvad, Surena UL; Chatzinotas, Symeon UL; Sachau, Jürgen UL

in Renewable Energy & Power Quality Journal (2014)

The last decade has seen a dramatic rise in renewable energy converters connected to the grid, consisting mostly of intermittent distributed generators on the medium or low voltage grid. Due to this ... [more ▼]

The last decade has seen a dramatic rise in renewable energy converters connected to the grid, consisting mostly of intermittent distributed generators on the medium or low voltage grid. Due to this evolution in energy transmission, improved monitoring and control of the distribution grid is becoming mandatory in order to efficiently integrate the new power sources and guarantee power quality, efficiency and reliability. Our paper describes a reliable and precise power grid impedance estimation method using an innovative scheme to control the Pulse Width Modulator’s pulse pattern on the inverters, in order to inject broad spectrum identification patterns. The generated harmonics and inter-harmonics will allow the online computation of the complete spectrum of the grid impedance at the Point of Common Coupling during normal operation. Simulations in typical grid situations verify that the proposed algorithm is robust to a realistic environment and can be used for automated feedback control. [less ▲]

Detailed reference viewed: 217 (12 UL)