Three-Phase State Estimation for Distribution-Grid Analytics

Power-distribution grids consist of assets such as transformers, cables, and switches, of which the proper utilization is essential for the provision of a secure and reliable power supply to end customers. Distribution-system operators (DSOs) are responsible for the operation and maintenance of these assets. Due to the increased use of renewable sources such as wind and solar, grid assets are prone to operation conditions outside safe boundaries, such as overloading, large voltage unbalance, and a rise in voltage. At present, distribution grids are poorly monitored by DSOs, and the above-mentioned problems may thereby go unnoticed until the failure of a critical asset occurs. The deployment of smart meters in distribution grids has enabled measurements of grid variables such as power, current, and voltage. However, their measurements are used only for billing purposes, and not for monitoring and improving the operating condition of distribution grids. In this paper, a state-estimation algorithm is proposed that utilizes smart-meter data for offline analysis, and estimates the loading of grid assets and power losses. Single- and three-phase state-estimation algorithms are compared through simulation studies on a real-life low-voltage distribution grid using measured smart-meter data. The three-phase state-estimation algorithm based on the nonlinear weighted least-squares method was found to be more accurate in estimating cable loading and line power losses. The proposed method is useful for DSOs to analyze power flows in their distribution grids and take necessary actions such as grid upgrades or the rerouting of power flows.

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Smart Meter Measurement-Based State Estimation for Monitoring of Low-Voltage Distribution Grids

Energies ◽

10.3390/en13205367 ◽

2020 ◽

Vol 13 (20) ◽

pp. 5367 ◽

Cited By ~ 1

Author(s):

Karthikeyan Nainar ◽

Florin Iov

Keyword(s):

State Estimation ◽

Real Time ◽

Low Voltage ◽

Weighted Least Squares ◽

Real Life ◽

Estimation Algorithm ◽

The State ◽

Smart Meter ◽

Voltage Distribution ◽

Distribution Grids

The installation of smart meters at customer premises provides opportunities for the monitoring of distribution grids. This paper addresses the problem of improving the observability of low-voltage distribution grids using smart metering infrastructure. In particular, this paper deals with the application of state estimation algorithm using smart meter measurements for near-real-time monitoring of low-voltage distribution grids. This application is proposed to use a nonlinear weighted least squares method-based algorithm for estimating the node voltages from minimum number of smart meter measurements. This paper mainly deals with sensitivity analysis of the state estimation algorithm with respect to multiple uncertainties for, e.g., measurements errors, line parameter errors, and pseudo-measurements. Simulation studies are conducted to estimate the accuracy of the DSSE under various operating scenarios of a real-life low-voltage grid, and cost-effective ways to improve the accuracy of the state estimation algorithm are also evaluated. The paper concludes that by using smart meter measurements from few locations, voltage profiles of the low-voltage grid can be estimated with reasonable accuracy in near-real-time.

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Three-Phase State Estimation of a Low-Voltage Distribution Network with Kalman Filter

Energies ◽

10.3390/en14217421 ◽

2021 ◽

Vol 14 (21) ◽

pp. 7421

Author(s):

Fabio Napolitano ◽

Juan Diego Rios Penaloza ◽

Fabio Tossani ◽

Alberto Borghetti ◽

Carlo Alberto Nucci

Keyword(s):

Kalman Filter ◽

State Estimation ◽

Phase State ◽

Low Voltage ◽

Distribution Network ◽

Estimation Algorithm ◽

The State ◽

Voltage Distribution ◽

Smart Meters ◽

Three Phase

The state estimation of distribution networks has long been considered a challenging task for the reduced availability of real-time measures with respect to the transmission network case. This issue is expected to be improved by the deployment of modern smart meters that can be polled at relatively short time intervals. On the other hand, the management of the information coming from many heterogeneous meters still poses major issues. If low-voltage distribution systems are of interest, a three-phase formulation should be employed for the state estimation due to the typical load imbalance. Moreover, smart meter data may not be perfectly synchronized. This paper presents the implementation of a three-phase state estimation algorithm of a real portion of a low-voltage distribution network with distributed generation equipped with smart meters. The paper compares the typical state estimation algorithm that implements the weighted least squares method with an algorithm based on an iterated Kalman filter. The influence of nonsynchronicity of measurements and of delays in communication and processing is analyzed for both approaches.

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A Two-Step State Estimation Algorithm for Hybrid AC-DC Distribution Grids

Energies ◽

10.3390/en14071967 ◽

2021 ◽

Vol 14 (7) ◽

pp. 1967

Author(s):

Gaurav Kumar Roy ◽

Marco Pau ◽

Ferdinanda Ponci ◽

Antonello Monti

Keyword(s):

State Estimation ◽

Distribution System ◽

Renewable Energy Sources ◽

Estimation Algorithm ◽

The State ◽

Second Step ◽

Distribution Grid ◽

Dc Distribution ◽

Attractive Option ◽

Distribution Grids

Direct Current (DC) grids are considered an attractive option for integrating high shares of renewable energy sources in the electrical distribution grid. Hence, in the future, Alternating Current (AC) and DC systems could be interconnected to form hybrid AC-DC distribution grids. This paper presents a two-step state estimation formulation for the monitoring of hybrid AC-DC grids. In the first step, state estimation is executed independently for the AC and DC areas of the distribution system. The second step refines the estimation results by exchanging boundary quantities at the AC-DC converters. To this purpose, the modulation index and phase angle control of the AC-DC converters are integrated into the second step of the proposed state estimation formulation. This allows providing additional inputs to the state estimation algorithm, which eventually leads to improve the accuracy of the state estimation results. Simulations on a sample AC-DC distribution grid are performed to highlight the benefits resulting from the integration of these converter control parameters for the estimation of both the AC and DC grid quantities.

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Full-Observable Three-Phase State Estimation Algorithm Applied to Electric Distribution Grids

Energies ◽

10.3390/en12071327 ◽

2019 ◽

Vol 12 (7) ◽

pp. 1327 ◽

Cited By ~ 7

Author(s):

Thiago Soares ◽

Ubiratan Bezerra ◽

Maria Tostes

Keyword(s):

State Estimation ◽

Real Time ◽

Distribution Systems ◽

Phase State ◽

Reactive Power ◽

Estimation Algorithm ◽

Load Flow ◽

Electrical Network ◽

The Real ◽

Three Phase

This paper proposes the development of a three-phase state estimation algorithm, which ensures complete observability for the electric network and a low investment cost for application in typical electric power distribution systems, which usually exhibit low levels of supervision facilities and measurement redundancy. Using the customers´ energy bills to calculate average demands, a three-phase load flow algorithm is run to generate pseudo-measurements of voltage magnitudes, active and reactive power injections, as well as current injections which are used to ensure the electrical network is full-observable, even with measurements available at only one point, the substation-feeder coupling point. The estimation process begins with a load flow solution for the customers´ average demand and uses an adjustment mechanism to track the real-time operating state to calculate the pseudo-measurements successively. Besides estimating the real-time operation state the proposed methodology also generates nontechnical losses estimation for each operation state. The effectiveness of the state estimation procedure is demonstrated by simulation results obtained for the IEEE 13-bus test network and for a real urban feeder.

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Impact of Solar Panel Orientation on the Integration of Solar Energy in Low-Voltage Distribution Grids

International Journal of Photoenergy ◽

10.1155/2020/2412780 ◽

2020 ◽

Vol 2020 ◽

pp. 1-13 ◽

Cited By ~ 3

Author(s):

Joannes I. Laveyne ◽

Dimitar Bozalakov ◽

Greet Van Eetvelde ◽

Lieven Vandevelde

Keyword(s):

Low Voltage ◽

Real Life ◽

Solar Panel ◽

Solar Panels ◽

Voltage Distribution ◽

Distribution Grid ◽

Voltage Balance ◽

Residential Distribution ◽

The Impact ◽

Distribution Grids

In Belgium, and many other countries, rooftop solar panels are becoming a ubiquitous form of decentralised energy production. The increasing share of these distributed installations however imposes many challenges on the operators of the low-voltage distribution grid. They must keep the voltage levels and voltage balance on their grids in check and are often regulatory required to provide sufficient reception capacity for new power producing installations. By placing solar panels in different inclinations and azimuth angles, power production profiles can possibly be shifted to align more with residential power consumption profiles. In this article, it is investigated if the orientation of solar panels can have a mitigating impact on the integration problems on residential low voltage distribution grids. An improved simulation model of a solar panel installation is constructed, which is used to simulate the impact on a residential distribution grid. To stay as close to real-life conditions as possible, real irradiation data and a model of an existing grid are used. Both the developed model as the results on grid impact are evaluated.

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