Modern Trends in Substation Technology and Advancement ...

7th Conference on Advances & Innovations in Substations on 25th -26th July 2019, New Delhi (Under the aegis of CIGRE NSC B3 on Substations & A3 on HV Equipment)

Modern Trends in Substation Technology and Advancement & Innovations in Substation Equipment

by

M.L. Sachdeva N.S.Sodha Former Chief Engineer Former Executive Director

CEA Power Grid, Gurgaon 25-26 July,2019

1. Modernization, Advancement & Innovation of S/S & S/S Equipment

Traditional Power System--Centralized Generation Plants, Unidirectional Power flow, Transmission and Distribution Systems.

Future Power System --Conventional ,Green & Renewable Energy Sources, Bidirectional Power flow

Digitalized Systems, e-mobility, Data Centers need an Intelligent System that can receive power from multiple sources and deliver reliably to Consumers/Prosumers

The 21st Century Power System Upgrade includes inter-alia ‘Modernization, Advancement & Innovation of S/S & S/S Equipment,’

CEA Report March, 2016: ‘Failure of S/S Equipment’ also suggests three stages :

i) Retrofitting of Existing S/Ss

ii) Implement New S/S Design

iii) Green Field Design

Modern Smart Grid Challenges

i) Retrofitting thru. use of Existing Components / Devices in Existing S/Ss considering penetration of Renewable & DERs

Retrofitting thru Digital Technology, Asset Management, Data Communication to Control Room/ SLDC/RLDC to Cloud to establish following:

Adding new equipment to supplement existing system as well as paving the way for future replacement of legacy solution;

Replacing existing equipment due to performance deterioration/ageing and making it compatible for total future replacement;

Balancing the need for Open System Design and Cyber Security while adopting the best practices and gradually training personnel for new technology/equipment

ii) Implementing New Designs (2020-30) envisages:-

Deployment of Off-the-Shelf Digitally integrated locally and /or Cloud connected Systems while expanding or new layout of substation equipment to facilitate integration between power apparatus and infrastructure for Monitoring, Control and Protection; LEDs with dimmer having local & remote control for Indoor & Outdoor Illumination; Wireless monitor SA; Power Quality & Energy Storage using various controllers, Cloud computing & analytics.

New Communication infrastructure including computing & data processing facilities at ‘Edge computing’, ‘ Fog / Control Room computing’ and ‘Cloud computing’ to support exchange of information with the control systems and neighboring substations, Cyber Security, Internet of Things (IoT) .

Transformers with digital capabilities enabling Remote monitoring & Data analytics of its vital parameters in real time. (Health data & actionable intelligence)

iii) Green Field Design covers designing of future Substations :- All the new built in Substations under i) & ii) above including optimization of the investment return and system operation cost, using completely new techniques, protocols, and apparatus viz. Super Capacitor, Solid-State Transformer (SST), latest design GIS, Gas/Oil free Optic Current & Voltage Transducers for Metering (NXVCT), Disconnecting Circuit Breaker with Fibre Optic Current Sensor, IoT, Composite Support Post Insulators etc. Future “Intelligent” Substations shall play important role in the overall “Smart Grid” with capability of providing health data and actionable intelligence.

Transformer with Various Sensors for Health Assessment ( Ref : ABB Ability (TM), Article 1/2019 )

2. Modernization, Advancement & Innovation of S/S Equipment

2.1 Digital / Electronic/ Solid State Transformers

Digital Transformers (Smart Transformers) – These are conventional transformers provided with all indicating and protective instruments with digital outputs instead of analogue as normal. Reputed Manufacturers (ABB, Siemens, SGB-SMIT, ---) are offering these and also Digital Distribution and Digital Power Transformers and Digital Dry Transformers.

Solid State Transformers ( Power Electronic Transformers) – Development work is going on for many years ( In India both BHEL and EMCO made some prototype distribution transformers ) but are expensive (8-10 times) However, these are used in Electric traction loco transformers thru conversion of power frequency supply to medium frequency through AC/DC/AC converter to feed to medium frequency loco-transformer which are lighter in weight. This advantage is more in case of 25 or 16 2/3 Hz used in some parts of Europe for Rail traction.

Electronic Transformer (German Approach)

Fig,1: Basic Design of Electronic Power Transformer (Ref 7) MF- Medium Frequency Transformer

Fig.2: Design of Electronic Power Transformer Building Blocks (Ref 7) 3-H Bridge VSC, DC-DC Module(Yd5 MF Trafo. & 3Phase2LVSC), MV Mod( H-bridge VSC)

Simplified Structure & Basic Control Schemes of Electronic Power Transformer* ( Ref.7)

*with addl. features like fast voltage regulation (flicker compensation), Active VAR compensation, Ride-Through Capability, Protection from Harmonic Distortion, Oil Free and using HV cables for transformer winding, no mineral oil or other dielectric thereby reduction in weight etc.

Fig.3: Simplified Structure & Basic Control Schemes of Electronic Power Transformer ( Ref.7)

Solid State Transformer

Fig. 4: 3-Phase SST Configuration (Ref.8) Fig.5: Modular 1-Phase SST Arrangement (Generic to replace Traditional Trafo.)

i) Rectifier stage (AC-DC)- Active Front end, ii) A dual active bridge (DAB) stage (DC-DC) with HF or MF transformer and iii) Back-end Inverter stage (DC-AC)

Case Study made by the Authors (Fig 5) (Ref.8) Capacity= 1.8MW ( 3x600KW / Phase),

HV distribution side=7.2kVrms/phase,

LV DC =400V for DC loads,

Switching devices = 6.5kV IGBT for HV side;

=1.2kV IGBT for LV side

Operating frequency of HF transformer =3kHz for self-switching operation

Note: For achieving required Current and Voltage Ratings, Input –series and Output-parallel connection of multiple SST modules has been considered

MULTI-PORT SS TRANSFORMER (MPSST) FOR FLEXIBLE DER INTEGRATION (Ref 9)

Fig.6: AC-AC Solid State Configuration (Ref.9)

Fig.7: Configuration of four Port SST (Ref.9)

MULTI-PORT SS TRANSFORMER (MPSST) FOR FLEXIBLE DER INTEGRATION (Ref 9)

Fig. 8: Feeding Multiple loads with Fig.9: Power Flow Control in a system with multi. Loads

components

(a) SST based system and a) SST based system and

b) MPSST base system (Ref.9) b) MPSST bases system (Ref.9)

Super capacitors with different construction materials to store energy are becoming competitor to Energy storage batteries.

Supercapacitors store energy using electrodes and electrolytes and both charge and deliver energy quickly as compared to conventional batteries which perform the same task in a much slower, more sustained way.

Supercapacitors have the ability to charge and discharge rapidly over very large numbers of cycles.

The construction of super capacitor using components of Carbon (requiring high temperatures and harsh chemicals to produce) has gone thru many changes viz.

‘Electrolyte interior for charging layers together with a faradic reaction with the electrode enabling charge transfer’(Ref.2), ‘Coated VACNT electrodes- a two-step process combining ALD with a chemical vapor deposition (CVD) that have precisely defined nanostructures and used with an ultra-high concentration lithium-ion electrolyte’ (Ref.3), ‘3-D surface-microporous graphene (Ref.4) ‘Metal-organic frameworks (MOFs)(Ref5 ), etc. to improve its capacitance rating, voltage rating, power capacity but making the same compact, improvement of life, environment performance.

2.2 Super Capacitor (SuperCap), Ultra capacitor, or Hybrids

2.3 Development GIS (Ref.11 &12)/Medium Voltage Switchgear (Ref 12a) (Compliance COP24)

Ref.11 (Mitsubishi) has mentioned developing two new technologies:

An arc-cooling technology achieving 25% improvement in the interruption of electrical current in SF6 gas-insulated EHV switchgear; and

High-density dielectric coating technology improving insulation performance by 30% of EHV current carrying conductors thereby leading to further miniaturization of switchgear and help reduce the use of SF6 gas.

Ref.12 (GE Power’s Grid Solutions) has mentioned launching a new 72.5kV compact F35 GIS capable to deliver reliable power to urban, industrial and windfarm applications:

23% bay volume reduction; and

30% reduction in SF6 mass

For Off -Shore wind turbines and collection platforms specifically, this enhanced design allows the power voltage transformer to feed auxiliaries under “no wind” conditions.

Ref.13 (Hitachi) mentions development of MV Switchgear(upto 52kV)deploying Hybrid VCB, Solid bus bar etc

2.4 Hybrid Outdoor ost insulators for EHV S/Ss (used in 400kV S/Ss) (Ref.10)

Working Group (WG) 12 of IEC TC 36, has worked out a technical specification for hybrid insulators titled ‘IEC/TS

62896 – Hybrid Insulators for AC and DC High-Voltage applications – definitions, test methods and acceptance

criteria’. The final document is approved to be published and will offer guidance on how to specify hybrid

insulators for relevant applications

2.5 Miscellaneous Equipment

i)Merging units,

ii) VSC (Voltage Source Converter preferred over conventional thyristor Valves) iii) Custom Power/ FACTs for lower voltage system

iv) PMU ( Phase Measurement Unit)

v) IEDs with microprocessors,

vi) Robotics and UAVs,

vii) Optic Current & Voltage Transducers for Metering (NXVCT),

viii) Disconnecting Circuit Breaker (DCB) with Fibre Optic Current Sensor (FOCS),

ix) Touchless S/Ss (Image capture & Visual Analytics Technologies, Transformer Monitoring & Life Assessment, Asset Management, reduce inspection visits)

x) Process Bus and Interoperability In Digital S/S

xi) LEDs with dimmer and local and Remote controls for indoor and outdoor illumination for S/Ss., peripheral Security fence, etc.

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8th Nov 2013 21

3. Conclusion

1.21st Century Power System (Conventional and Renewable & DER Resources) changing to 2 -way Power Flow System is further tending to Digitalization for handling large & speedy processing of Data reliably. 2.Retrofitting Existing Substations in full swing providing communication protocol, intelligent electronic devices, smart power converter, etc.in distribution system and operating standards to improve the overall performance without disrupting the continuity of service. For this purpose, upgrading and expanding the existing substation equipment using latest technologies thru the use of wireless and optical fiber communication media when adding new equipment and using software integration of data. 3. Green Field Design inter-alia covers technology development of: Solid-state Transformers deploying a combination of high & Medium frequency power electronic

converters and a multi-winding high-frequency transformer leading to size reduction with the same voltage and power rating and different fast control facilities;

Super Capacitor for storage of energy similar to energy storage batteries offering quick discharge and fast charging for meeting system peaking demand, use in EV charging stations and communication towers as a change source between main and standby power source.

4. Some of the GIS Manufacturers in compliance with COP24 to reduce green house gases, made modification in the GIS to reduce volume of SF6 & size as also for Off-Shore Wind Turbines Platform, an enhanced design to facilitate the Power Voltage Transformer to feed auxiliaries under “no wind” condition 5. Indian R&D / Manufacturers/ ITs shall take up development digital MF/HF transformers, switchgear, Super Capacitor , Asset Management Platform , communication system, cyber security, etc. to facilitate reliable operation of conventional ,Renewable and DER as a composite grid , MV Switchgear upto 66kV (similar to Hitachi going upto 52kV less SF6 )

4. References 1(a) REPORT ON FAILURE OF 220 KV AND ABOVE VOLTAGE CLASS SUBSTATION EQUIPMENT, CENTRAL ELECTRICITY AUTHORITY, MOP, GOI, NEW DELHI, March, 2016 1. Mladen KeKezunovic et -all Taxas A&M University and Georage Karady et-al Arizona State University: ‘The 21st Century S/S Design’ Power Systems Engineering Research Centre’ Final Project Report-Sept 2010} 2. OCTOPART: ‘Supercapacitors Provide Power Holdup for Renewable Hybrid Energy Storage Systems’, THU 21 JUNE 2018 3. US Department of Energy: ‘As future batteries, Hybrid Super Capacitors are Super-charged’, 20th June 2018 4. Allison Mills:’From greenhouse gas to 3-D surface-microporous graphene’ Michigan Technological University, 3rd Aug 2017 (Study published American Chemical Society's Applied Materials & Interfaces.) 5. Massachusetts Institute of Technology: ‘New kind of supercapacitor made without carbon’ 10th Oct 2016 6 . SGB-SMIT Group 12th Nov 2018: SMART GRIDS, INTELLIGENT TRANSFORMERS: SGB-SMIT SWITCHES TO DIGITAL CONTROL WITH IMMEDIATE EFFECT 7. Holger Wrede Volker Staudt Andreas Steimel, Ruhr-University at Bochum, Germany : ‘Design of an Electronic Power Transformer’(0-7803-7474-602/517.00@IEEE) 8. Roderick Javier Garcia Montoya: ‘High-Frequency Transformer Design for Solid-State Transformers in Electric Power Distribution Systems’, University of Arkansas, Fayetteville Theses, 12-2015 9. Mohammad Rashidi, University of Wisconsin:’DESIGN AND IMPLEMENTATION OF A MILTI-PORT SOLID STATE TRANSFORMRE FOR FLEXIBLE DER INTEGRATION,’Dec 2017 10. INMAR 21June 2019: Technical Review of Hybrid Insulators 11. Mitsubishi Electric Develops New Gas-insulated Switchgear Technologies for Electric Power Applications: Environmental Friendly Technology reduces usage of Sulfur Fluoride: Feb 04, 2019 12. GE Power Grid Solutions (CIGRE Aug 2018) 13. Kenji Tsuchiya et-al:’Development of Medium-voltage Switchgear for Reducing Environmental Impact and Space-saving’ Hitachi Review Vol 63(2014) No4

Thank you

for

Kind Attention Please

i) Retrofitting thru extending use of Existing Components / Devices in Existing S/Ss considering penetration of Renewable & DERs in the Conventional system

Use of FACTs, SVCs, STATCOMs for controlling Reactive Power for Voltage Stability. GIS & AIS to be fixed with control, protection & communication features for integration with SAS using IEC

61850 thru Merging units. S/S expansion thru Deployment of Hybrid Switchgear conforming IEC 61850 Use of WAMS deploying PMU for real time Grid Status Monitoring using GPS to measure phase, current &

Voltage for maintaining system stability over limitation of SCADA which directly measure voltage & current only.

Deployment of Sensors in Transformers for measurements of ambient and top-oil temperatures, levels, pressure, moisture, voltage, current, hydrogen, and global positioning (GPS) and Local analytics: consumed transformer lifetime, total harmonic distortion (THD), expandable for additional analytics

Local built-in Wi-Fi to download data. Wired Ethernet is enabled to connect to LTE, GSM, wireless mesh, WAN, and others mediums using standard protocols, DNP3.0, IEC61850, etc.

Basic configurator user interface (download the data update/ upgrade firmware and set the parameters) Volt-VAr Management Software (VVMS) - Centralized Distribution Automation Software, Capacitor bank

Controller On-Line SF6 gas transmitter, Portable SF6 gas Detector