STUDY AND ANALYSIS OF SYSTEMS FOR MONITORING IN

POWER SUBSTATIONS

NIKOLINA PETKOVA, VALERI MLADENOV

Department of Theoretical Electrical Engineering

Technical University of Sofia

Sofia 1000, boulevard Kliment Ohridski 8

BULGARIA

valerim@tu-sofia.bg

ANGEL TSOLOV, PETAR NAKOV

Department of Electrical Energetic

Technical University of Sofia

Sofia 1000, boulevard Kliment Ohridski 8

BULGARIA

GEORGI BOZUKOV

National Dispatching Center, Electricity System Operator (ESO)

5, Veslets Str., 1040 Sofia, BULGARIA

gbozukov@ndc.bg

Abstract: The intensive development of science and technology in all areas of our daily live reflects and in the

systems for monitoring and recording processes of abnormal modes in the power equipment of substations.

Monitoring systems report their apogee in the development and application because of the fact that with

minimal human effort it is possible to obtain maximum information about the observed object. The research

work describes an analysis of transmission and record of data that are required for control transformers in

service.

Key words: Monitoring system, Power substation, Application, Development.

1 Introduction Monitoring systems provides all the technical

information required to maintain utmost availability

and at the same time maximize performance,

including loading and lifetime benefits. This

advanced monitoring solution surveys every link in

the energy supply chain. Accurate monitoring of all

primary components of a substation makes possible

optimized loading and performance, and it helps

increase the lifetime of the line.

The aging factors produce electrical, thermal,

mechanical, or environmental aging mechanisms

that eventually lead to failure. When aging is

dominated by one aging factor, this is referred to as

single-factor aging. Aging factors may act

synergistically, that is, there may be direct

interactions between the stresses. Interactions may

be positive or negative. The aging of a practical

work can be complex and failure is usually caused

by a combination of aging mechanisms, even though

there may be only one dominant aging factor. From

the large number of measurement and monitoring

methods and techniques we select these that are

currently in use in Nikola Tesla Institute [1].

Fig.1: Testing-monitoring-diagnostics management

system

2 AREVA - MS 2000/3000 Systems During the last years the AREVA monitoring

system MS 2000 was installed world-wide at power

transformers of all major manufacturers. The online

monitoring systems from Areva T&D provide

precise information about the operating state of

Recent Researches in System Science

ISBN: 978-1-61804-023-7 402

power transformers and are the basis for increased

availability, cost optimization through condition-

based servicing, and avoidance of faults and

downtime. [2]

Normally the installation of sensors requires no

welding at the transformer and takes about two days.

The transformer has to be taken out of operation

only for half a day to install the voltage sensors and

the tap changer monitoring module. [2]

An additional module installed on the MS 2000

monitoring server generates HTML-based web

pages, which show the online and historical data for:

��� Operating voltages and over voltages;

��� Load currents, over- and short- circuit

currents;

��� Leakage current and change of capacitance;

��� Apparent power and bad factor;

��� Oil pressure and pressure difference;

��� Oil level;

��� Operating condition of fans and pumps;

��� Ambient temperature;

��� Oil temperatures in/out cooler;

��� Cooling efficiency and thermal model;

��� Actual losses;

��� Oil temperature;

��� Gas-m-oil content and gradient;

��� Moisture-in-oil and paper insulation;

��� Gas quantity in the Buchholz relay;

��� Calculation of actual overload capacity;

��� Emergency overloading time;

��� Hot-spot/bubbling temperature;

��� Ageing rate and lifetime consumption;

��� Power consumption of motor drive;

��� Oil temperature and temperature difference;

��� Assessment of mechanical quality;

��� Sum of switched load current;

��� Contact erosion. [2]

3 OMICRON - MPD 600, PD-TM, PD-

MAT Systems The OMICRON Transformer Diagnostic System is

unique test equipment which provides automatic

testing of important transformer parameters within

one portable system. The test system is comprised of

the CPC 100 Multi-function Primary Test. System

and the CP TD1 Tangent Delta unit. The patented

CPC100 is the main control unit for the test system

and the CP TD1 unit is used for testing of insulation

condition. Together, the system is the ideal tool for

comprehensive testing of the following parameters

of a power transformer:

• Winding resistance - Measures the winding

resistance including all internal connections and

contacts.

• Measures ratio and excitation current per

tap - For this test, a test voltage of up to 2kV is

injected on the transformer high voltage side. This

voltage is measured internally with high precision.

The voltage (amplitude and phase angle) on the low

level voltage winding is measured back via the

measuring input. The ratio is calculated

automatically. The magnetizing current in amplitude

and phase angle is also measured and reported.

• Turns ratio and excitation current

• On-load tap changer condition

• Leakage reactance - Measures the complex

short circuit impedance and displays the result as Z

and ϕ, R and XL, or R and L.

• Insulation condition (capacitance, tangent

delta, power factor). [3]

4 SIEMENS - TMDS™ Systems TMDS™ architecture uses models that work with

rule-based logic, derived from accepted IEEE/ANSI

guidelines, to perform correlations on measured and

calculated data. It is configurable to monitor a single

transformer or an entire fleet of transformers to

support a customer’s centralized approach to asset

management, and turns transformer monitoring data

into actionable information through diagnostic and

prognostic messaging. TMDS™ can detect

statistically significant breakouts before hard limits

are reached to avoid nuisance trips and alarms, far

exceeding existing monitoring concepts of simple

measurement of operative condition with pre-fixed

limits. Only meaningful data is retained to support

correlation between variables. [4]

Variables monitored, depending on sensors

installed, include:

• Winding temperature

• Top and bottom oil temperatures

• Ambient temperature

• Load current

• Fan motor current

• Oil flow (pump motor)

• Moisture in oil Aquaoil Vaisala

• Dissolved gas in oil Multi-gas Serveron

TM8 Siemens GAS-Guard 8 Kelman

MULTITRANS Single-gas Calisto Hydra

• Bushing condition Doble IDD HSP

• LTC monitoring

• Oil level

Recent Researches in System Science

ISBN: 978-1-61804-023-7 403

Fig. 2: Siemens Monitoring System

5 ABB - TSTAT Transformer Monitor TSTAT is a condition monitoring system that

provides a comprehensive end-to-end solution for

the remote monitoring of critical transformers and

their supporting systems / components (LTC’s,

fans, pumps, selector switches, etc.). The system

collects and analyzes key operating parameters and

event data, and provides users with web-based

access to real-time data, alarms, trends, condition

status summaries, and reports. This coupled with

an advanced analysis and algorithm engine,

reduces time spent reviewing data, and provides

useful recommendations for managing and

optimizing transformer performance and

maintenance. Primary features include Main

Tank/Windings, Tap Changer, Cooling System

Performance, Nitrogen/Conservator System and

Bushings.

Transformer monitoring is becoming an essential

component of transformer management. It serves as

an early warning system for any fault developing in

the main tank and in the accessories, allowing an

operator to evaluate the severity of the situation. [5]

Fig. 3 Structure of transformer monitoring system

The interface provides exact status information

by generating a model of the transformer and its

working condition and then comparing the measured

parameters with the simulated values. Discrepancies

are detected and potential malfunctions and normal

wear in the transformer and its ancillaries are

indicated. The monitoring system also tracks

transformer alarms, recording an actual event as

well as the sequence leading up to the alarm to assist

operators in determining the root cause. The benefits

of monitoring are substantial. The strength of

ABB’s Transformer Electronic Control, or TEC,

monitoring system is that it receives all the relevant

information from just a few multipurpose sensors.

Other necessary parameters are calculated, adding

only minimal complexity to the transformer. The

end user is no longer forced to spend a lot of time

sorting and interpreting data. In addition, the

maintenance manager receives important

information indicating the necessary actions for

first-level maintenance. [5]

6 Conclusions Competitive electric energy market drives utilities to

adapt to a lot of changing technical and economical

requirements, so transformers and systems for their

testing, monitoring and diagnostic have developed

together with the power supply systems. [1]

The needs of transition from the conservative

corrective and time based strategies toward

condition based maintenance, has encouraged the

development of adaptable and cost-effective

diagnostics.

7 Acknowledgements The work was supported by FR7 project South–

East European TSO Challenges (SEETSOC),

TREN/FP7EN/239453/"SEETSOC".

References:

[1] Integrated management system for testing,

monitoring and diagnostic of power transformer

insulation, D. Kovacevic, D. Naumovic – Vicovic,

S. Skundric, Institute Nicola Tesla, Belgrade, Serbia

[2] MiCOM P125/P126 & P127, Technical Guide,

Areva T&D's Automation & Information Systems

Business

[3] CP Line Catalog DEU, Omicron Test Universe

[4] Solutions for transformer life-cycle

management, Siemens TMDS

transformer

monitoring and diagnostic system, Siemense AG,

2010

[5] ABB TrafoAsset Management – Proactive

Services, ABB Review, 2010

Recent Researches in System Science

ISBN: 978-1-61804-023-7 404