2020 International Russian Automation Conference (RusAutoCon)

Digital Twins for Electric Grids

D. S. Zolin E. N. Ryzhkova
National Research University "MPEI" National Research University "MPEI"
Moscow, Russia Moscow, Russia
diffl@mail.ru ryzhkovayn@mpei.ru

Abstract—This article describes the main applications of

digital twins in operating a digital substation. It evaluates the
associated features and benefits that are covered herein
applicably to transmission and distribution grids alike, since they
differ in their fundamental operating principles when it comes to
modeling. Normal and emergency operation of a real substation
is modeled to demonstrate the informativeness and control
capabilities of a digital-twin enabled facility. The technology
improves the informativeness of automatic control system while
also being capable of automated analysis of controlled
parameters for comprehensive representation of the substation’s
operating status.

Keywords—digital double, PSS®ODMS, PSS®SINCAL,

geographic information system

I. INTRODUCTION
Fig. 1. Digital grid twin flowchart.
Russia’s energy infrastructure is being digitalized as part of
framework of the Decree of the President of Russia dated Digital twins are of great interest for electricity providers
07.05.2018 No. 204 On national goals and strategic objectives today, since a company might have only one physical grid with
of the development of the Russian Federation for the period dozens of representations from department to department. Each
until 2024. Pursuant thereto, Rosseti drafted its Digital model is used for different purposes and with different
Transformation 2030 Concept in late 2018, which reflects the software (for example, for network parameter calculations,
principles and basic steps of grid digitalization. The concept scheduling, asset management, accounting systems, etc.).
implies not only building digital substations or digital power Inconsistencies in the model data at different departments may
grid areas (PGA), but also a paradigm shift in the operation of lead to inaccuracies in grid representation, suboptimal system
electric grids to adopt such novel technologies as Big Data, performance, and excessive manual effort required to keep
cloud systems, IoT, advanced distribution management these models up to date. Digital twins thus offer the following
systems (ADMS), and digital twins. Rosseti projects the core advantages:
Concept to unfold by 2030 and cost 1.3 RUB trillion.
• A more accurate and consistent model (a single source
Digitalization refers to a wide range of technologies and of data) for calculations and operation, including:
solutions that should ultimately lead to the creation of digital
grids. All these solutions combine automated business − reduced risk of grave operational / scheduling errors
processes and process routines into streams automated business caused by incorrect model data;
processes, which relieves human operator from making day-to- − tracking changes in the model with the ability to
day decisions [1]. The goal of digitalization is not only to adopt recreate cases after something has been changed
advanced hardware and software, but also to combine business (“audit log”);
processes and process routines for less erroneous, faster, and
more accurate decision-making. − an ability to interact with key data sources and
functions, for example, the asset management system
II. DIGITAL TWINS FOR ELECTRIC GRIDS or the GIS.

Among other things, digitalization produces digital twins • More efficient and optimal planning and operational
for grids; a twin is essentially a single database containing the processes, including:
necessary information about the grid, which is integrated with − elimination of existing duplicate processes thanks to
other subsystems of the company. It automatically using shared grid models for planning and operation;
synchronizes data received from different sources in such a
way that a single digital model corresponds to a single physical − process automation, e.g. computer-aided distribution
grid, see Fig. 1. grid modeling;

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 2020 International Russian Automation Conference (RusAutoCon)
− less time-consuming grid connection; 67.7%. The company is responsible for the planning and
development of Finland’s grids; as such, it serves as a grid
− а unified process for modeling and data management service provider for the electricity market actors, manages the
for a variety of functions. electricity market, and ensures grid safety and market
• Easier integration of subsystems in the future and more transparency. Finland’s grids comprise 116 substations, 4,600
extensive overall digitalization of the company, km of 400-kV lines, 2,200 km 220-kV lines, and 7,600 km of
including: 110-kV lines. The ELVIS project addresses some of the most
important issues pertaining to grid asset and operation
− more efficient use of grid resources resulting in management: interoperability, transparency, and consolidation
maximum possible utilization rates; of data usually obtained from multiple heterogeneous systems.
ELVIS brings together asset data from eight different products
− adaptive relay protection settings;
(including Siemens PSS®ODMS and PSS®E), combining
− the need to boost the grid arising later or not arising at several suppliers into a complete system that enables
all; unrestrained inter-product communications. These products
cover the main functions: network parameter calculation
− real-time simulation, e.g. to prevent power outages (PSS®E), protection parameter calculation, data management
through dynamic assessment and protection safety of relay protection settings, network modeling and data
assessment, enabling day-ahead forecasts. management (ODMS PSS®), portfolio / project management,
It should be noted that transmission grid operators differ geospatial analysis tools, and production management systems.
from distribution grid operators even though both work to At the heart of this digital twin is PSS®ODMS, an application
transmit electricity and maintain their assets. A CIM database that enables the Company’s engineers to quickly and easily
(for example, using Siemens PSS®ODMS software) can serve maintain, analyze, and share grid-related data. Thanks to its
as a digital twin for transmission grids. For a distribution grid, open architecture and core design based on the IEC CIM 61970
it suffices to have a GIS-complemented database created by standard, ODMS PSS® is a centerpiece that interfaces with
grid calculation software (for example, PSS®SINCAL) as a multiple ELVIS applications, including PSS®E, ArcGIS,
single data source. This difference lies in the fact that Maximo, PI Historian, and a data loading system developed by
distribution grids have a much larger number of elements, Fingrid (Fig. 2).
which, coupled with frequent changes, generates huge data These interfaces support many applications related to the
arrays that are rather difficult to process [2]. GIS- network planning and modeling studies using integrated data
PSS®SINCAL integration optimizes data processing. from the asset management system. The ELVIS project
addresses some of the most serious issues of asset
III. EXAMPLE OF DIGITAL TWIN IMPLEMENTATION FOR management, as it provides uninterrupted information
TRANSMISSION GRIDS exchange between several products at each stage of asset
management workflows and energy system planning. As a
The ELVIS project (ELectricity Verkko Information
result, Fingrid has an asset management system that improves
System), implemented by Fingrid in 2016 [3] is an exemplary
business process efficiency and productivity, reduces costs,
digital twin for a transmission grid. Fingrid is an open joint
improves reliability and customer satisfaction, and provides
stock company with a limited liability which is state-owned at
more efficient and effective decision making.

Fig. 2. Structure scheme of a digital double from Fingrid company.

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IV. EXAMPLE OF DIGITAL TWIN IMPLEMENTATION FOR

DISTRIBUTION GRIDS
Slovakia’s VSE Group (part of the European RWE Group)
has integrated a geoinformation system (GIS) with PSS
SINCAL, which now serves as an example of a digital
distribution-grid twin. The VSE group, which is part of the
European RWE group, includes several companies, one of
which is VSD, the distribution system operator in Slovakia.
Each year, the electricity provider transmits 3,800 GWh of
electricity in a geographical area equivalent to one third of
eastern Slovakia, or about 16,200 sq. km. The distribution grid
serves over 610,000 households through 34 110/22-kV
substations and 6,000 22 / 0.4-kV substations. The total length
of 110-kV, 22-kV and 0.4-kV overhead lines and cable grids is
21 thousand km [4]. By 2009, the company had installed
numerous IT systems (SCADA, GIS, SAP), which required an
up-to-date electric grid model to operate efficiently.
Implementing the grid parameter calculation suite was the final
stage of creating the digital twin. At the time, the model was
created manually, a time-consuming process (~500 h to create
the whole-grid model) that was associated with inaccuracies
and lack of flexibility, since the model had to be updated for
any grid changes. In 2011, PSS SINCAL (Fig. 3, 4), won
competitive bidding; it is a grid parameter calculation suite that Fig. 3. Flowchart of a 110/10kV step-down substation.
uses an open database and provides a convenient user interface
that can visualize grids and map them. Software for the twin
was selected by two criteria: distribution grid model quality
and model build time. The digital twin project has created an
adapter to serve as an interface between two standardized
software products. The adapter reads GIS data and translates it
into a format readable by PSS®SINCAL. Aside from the GIS,
the adapter is not connected to any other system such as
SCADA or SAP. After converting data from the GIS, auxiliary
information (databases) is added directly to the adapter-
converted database. This functionality can be used to add
equipment and protection parameters including low-voltage
equipment parameters. The measured feeder power values are
also used to adjust the load values (specified in the model as
the maximum values) to generate a grid model close to the
actual grid state. Supporting databases were prepared by the
VSE Group administrators, which turned out to be much Fig. 4. Current protection selectivity map.
simpler than creating interfaces for the remaining subsystems.
Thanks to automatic data conversion, the user can quickly V. EXAMPLE OF STEP-DOWN SUBSTATION EMERGENCY
create an accurate distribution grid model. In the past, MODE SIMULATION
modeling one of the medium-voltage areas, about one-eighth of
the entire VSE Group system, would take up to 500 hours. The complexity of a power transmission system (PTS) as
Now there is a solution that employs automatic data conversion well as its characteristic properties in both normal and transient
to create a more accurate similarly sized grid model much operations must be taken into account if the PTS is to run
faster, as it takes three hours at max. The Group’s solution thus smoothly. This calls for stricter requirements to R&D, reduced
significantly improved the quality of distribution grid analysis. electricity losses, and adoption of highly reliable equipment [5-
A future development specialist can now dedicate more time to 7].
grid analysis instead of creating and maintaining a grid model Preset parameters of the system and substation.
manually. Since this is a 1:1 conversion from the GIS, the
results of various calculations can be easily compared with System power S = 1900 MVA
other systems or linked to the real-grid equipment. For Selecting the main electrical equipment according to the
example, equipment maintenance scheduling is now based on formulas below were obtained the maximum three-phase short-
calculating the parameters of medium-voltage grids. circuit currents, using a refined calculation, at points K1-K2
(table. 4).

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A PTS normally has a uniform design that combines an TABLE III. SELECTED MOTORS
optimized circuit and specially selected power and switching
Transformer number Transformer type
equipment plus relay protections and automations [8]. Relay
protections and automations, whose quality has been steadily М1,М2 АN-15-41-6
improving as of recently, do affect the quality, reliability, and
stability of the PTS as a whole. An RPA is a system that
comprises individual units and is designed to timely respond to Methodological calculations of microprocessor protections
the escalation of an emergency so as to locate the affected site were run [5, 12] to obtain tripping current values:
and disable the damaged PTS components. Each • current cutoffs (without and with a time offset);
microprocessor unit calculates the ‘settings’ to timely detect
and record exceeded emergency thresholds [5]. Research • maximum current protection.
presented herein is based on refined calculation of short These were further used to make a selectivity map for the
circuits coupled with mathematical modeling in MATLAB- modeled circuit.
Simulink. Given the system capacity, transformer and motor
types, line lengths, and microprocessor protection types (see The switch is implemented as a set of separate elements
Tables 1 to 3) as shown in Figure 1, the following was selected and is presented in Fig. 5
[9–11]:
Time settings are implemented in Transport Delay, while
• outgoing lines; the current setting is a constant, reaching which triggers the
Switch that disconnected the affected grid element. Imagine
• short-circuit currents at the points indicated in Fig. 3. system simulation step-down substation 110 / 10.5 kV (in the
Below are the parameters of the step-down substation software package Matlab, Simulink) (fig. 6). For simplicity,
circuit (Tables 1 to 3). calculate half of the system. Consider a fault (short circuit) at
K-1. Generate the current and voltage over time graphs, see
Figures 7 to 12).
TABLE I. SPECIFICATIONS OF SELECTED LINES
The graphs show that as an SC occurs (Fig. 9), current
Line Resistance, Reactance, Line
number
Line type
r0, Ohm x0, Ohm length, km
exceeding 3556,7 A comes in a second of system runtime and
W1,W2 AS-70/11 0.0753 0.109 30 causes a voltage sag, Fig. 10. The switch Q1 trips after 1,20
W3,W8 AAShv-10-3х70 0.155 0.0415 0.4 sec. triggering the time offset configured in the Transport
W4-W7 AAShv-10-3х95 0.468 0.0396 0.5 Delay. Q1 follows the selectivity map shown in Fig. 4. These
data match the calculations. The proposed short-circuit
TABLE II. SELECTED TRANSFORMERS simulation is suitable for demonstration and verification of
Transformer number Transformer type
calculations in production and in teaching.
T1 TDN-16000/110/10
T2 TSZ-400

Fig. 5. Switch implementation in MATLAB

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Fig. 9. Current over time upon short circuit.

Fig. 6. Simulation model of a 110/10.5-kV step-down substation.

Fig. 10. Voltage over time upon short circuit

Fig. 7. Current over time, complete simulation.

Fig. 11. Current over time upon Q1 disconnection.

Fig. 8. Voltage over time, complete simulation.

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 2020 International Russian Automation Conference (RusAutoCon)
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