ADVANCE CONTROL AND MONITORING IN SECONDARY SUBSTATION-PROJECT UPGRID

The paper presents a detailed description of the integrated AMI (advanced Metering Infrastructure) and Smart Grid (SG) solutions in the secondary substations (SS) and the experience gained during the project UPGRID. The integration of hardware communication solution in SS is also one of the new concept deployed within UPGRID project and described in the paper.


INTRODUCTION
Sustainable development, quality of supply and the efficient use of energy, as well as an increase in the share of renewable energy sources, are keys to the development of a power sector in the European Union in the coming years.These trends will have a significant impact on the operation of the distribution grid.Overcoming these challenges can be done through the implementation of Smart Grids solutions.SG of the future should provide much more information than now, especially in medium voltage (MV) and low voltage (LV) networks.The development of SG requires an increase observability of the MV and LV network.Increase of network observability can be provided by new solutions for all secondary substation.New concept of a smart substations integrated AMI infrastructure and monitoring and control devices is developed in UPGRID project as the Polish demonstration part.The UPGRID project is an international project carried out in the European Union as a part of the Horizon 2020 program.The main objective of the UPGRID project is to develop functionality that serves the integration of MV and LV networks with the management systems of the demand and distributed generation side.The new, integrated AMI and SG cabinets with three different levels of equipment are installed in all the secondary substations, located in the Polish demonstration area.Each SS is equipped with a fault current detection device in the MV network.About 30% of the SS are prepared to remotely control the MV switching devices.In order to increase the observability of the LV network, selected stations are equipped with LV switchgears, allowing the full monitoring of the electrical parameters of the feeders and fuse monitoring.

Quality of supply requirements
Legalized in 2016 quality regulation for Polish Distribution System Operators (DSO) states that the described below indicators will have a direct impact on the amount of legalized DSO revenue in 2016-2020: • System Average Interruption Duration Index SAIDI, • System Average Interruption Frequency Index SAIFI, • duration of the customer installation connection, • time of transfer of the metering and billing data, which will be introduced to control the quality from the year 2018.The aim of the new regulation is to reduce the average SAIDI index to 136 minutes in 2020.In Poland in 2014 SAIDI index was 272 minutes, while in most European countries it is less than 60 minutes.According to the report of the Council of European Energy Regulators (CEER) [1], about 75% of the SAIDI and SAIFI indices for customers on low voltage (LV) stem from events in the network medium voltage (MV), 20% in the lowvoltage network, and only approx.5% of the events in the high-voltage (HV).

Increasing amount of renewable energy
Another challenge is to manage the increasing amount of renewable energy sources installed mostly in low voltage grid.From the point of view of a DSO the distributed renewable energy sources constitute, to some extent, a hazard to the LV network operation.This hazard is associated with a strong relationship between the generated power and the forces of nature (wind speed, sunlight).An increased number of micro-generation systems (in case of Polish network -PV installation) can potentially result in the following problems: increase of voltage levels above the admissible values and overloads of network elements (lines and transformers).

Cyber security
So far the LV distribution network area has not been adequately monitored while control functions have not been used at all by DSOs in Poland.Massive deployment of AMI devices esp.Data Concentrators from communication perspective results in the installation of thousands of LANs in the field.This LANs can also be used for supervision and control, but cyber security problems have to be solved.

Installation of the communication devices on a massive
Paper 0839 CIRED2017 2/4 scale (hundreds of thousands) in the relatively easily accessible places (MV/LV substations) can make them vulnerable to hacker attacks.
Proper cyber security measures have to be deployed.

NEW TOOLS
Mass deployment of AMI infrastructure and the installation of new equipment for the MV and LV network monitoring allows the DSO to collect more data about the state of the distribution network.This data can be used to implement new solutions to increase the level of control and monitoring of the distribution network, such as a network analysis module (NA) of Distribution Management System (DMS).NA performs power flow calculations in MV and LV network in quasi real time.
Another example is using historical data from AMI to create profile of load and distributed generation used for LV network power flow.AMI meters are also able to provide information about events occurring in the LV network, ie.power loss of one phase, communication problems or voltage dip.This information can be used by Outage Management System (OMS) -another module of DMS system.Real time power flows information in LV network is a whole new quality of LV network management.Based on this information DSOs are able to control and manage network in a much more efficient way, increasing the reliability of the distribution network.
The key however, is to ensure appropriate quality information about the state of the network.

INTEGRATED SMART GRID SOLUTION
The idea of integrated solution The idea of integrated technical solution of the monitoring and control devices has been applied to three different deployment levels resulting from their role in MV grid: The integration of hardware communication solutions in MV/LV transformer substations is the focal point which is described and used in the UPGRID project solution.In practice it connect both AMI data concentrator and the SG remote control and monitoring unit to the common wireless communication router.Placing all devices together with common uninterruptible power supply unit in one common cabinet in the indoor MV/LV substations allows to build the solutions cheaper and make them easier to manage by DSO.Communication is performed by two independent communication channels (two different technologies CDMA + LTE and UMTS) to two main IT systems: dispatcher system SCADA and AMI system.In order to increase the level of observability of LV network, part of the Smart Grid monitoring and control units in SS installed in the UPGRID project were additionally equipped with a system for monitoring the LV circuits in new LV switchgears, making it possible to monitor the key electrical values, i.e. current, voltage, active and reactive power and fuse link burn-out in each line bay.

CYBER SECURITY ISSUES
Integrated communication approach can facilitate the solution of cyber security issues.Installation of the communication devices on a massive scale (hundreds of thousands) in the relatively easily accessible places (MV/LV substations) can make them vulnerable to hacker attacks.Security measures should be built into every piece of equipment installed in cubicle.Beside the well-known "encryption" method also authentication, role-based access control and prevention of denial of services should be applied.
Ensuring information security of industrial systems with a complex structure and potentially tens of thousands of physical access points is possible, but requires the development and implementation of both the terminal devices, network elements (routers) and IT infrastructure with adequate safeguards.All of them should be an interconnected system, which, together with the monitoring of attempted unauthorized access, can provide effective protection.It is not possible and technically justified to implement partial solutions, ie.only on the level of RTU or only at the level of central systems.
Existing security systems and techniques in the field of IT can be successfully used in the field of OT systems, but only in the case when it was a conscious and logical decision.It is necessary to formulate requirements for information security for all devices attached to the network.It is also recommended to verify the practical solutions implemented in a particular computing environment of OT systems.
In particular, this includes such techniques as: • ensuring the confidentiality, integrity, sent / offered information; • authentication and authorization for terminal devices that are seeking access to information; • use of solutions to protect against intrusion by unauthorized persons looking for data resources; • use protection for computer systems against malicious software (malware).

SUMMARY
Implementation of innovative solutions in the area of Smart Grid is one way to address current and future DSOs challenges.More and more emphasis in the future will be put on issues related to power quality and power supply reliability.It is crucial to develop as well as building systems for monitoring and control of network including LV level, that enable flexible work of the distribution network.The experience and knowledge gathered in the UPGRID project will allow ENRGA-OPERATOR to decide on further directions of the development and implementation of solutions in the Smart Grid area to ensure the highest quality of service in terms of quality and reliability of supply.At this stage many benefits are visible from the integration of AMI and SG solutions as well as other areas of possible improvement ie.building systems based on standard connectors from devices inside the cabinet like RTU, communication unit, power supply.The project also shows that AMI may constitute the main source of data needed for effective network LV management.

Fig 4 .
Fig 4. Integrated AMI and SG cabinet for different types of SS Integrated solution at telecommunication layer (one smart communication unit) allowed the implementation of the new approach for transfer measurement and data from AMI meters and RTU data installed in SS.Communication is performed by two independent communication channels (two different technologies CDMA + LTE and UMTS) to two main IT systems: dispatcher system SCADA and AMI system.In order to increase the level of observability of LV network, part of the Smart Grid monitoring and control units in SS installed in the UPGRID project were additionally equipped with a system for monitoring the LV circuits in new LV switchgears, making it possible to monitor the key electrical values, i.e. current, voltage, active and reactive power and fuse link burn-out in each line bay.Fig 5. AMI/SG cabinet type 3 Fig 5. AMI/SG cabinet type 3

Fig 6 .
Fig 6.Communication scheme used in UPGRID project In the case of UPGRID project the following cyber security measures have been deployed (Fig. 6): • DNS server registration, • authentication 802.1xRADIUS (login, password), • authentication 802.1xTLS by Certificate CA, client certificate, private key, • certificate replacement in the cyclic way, • IPsec tunnels for RTU and AMI Data Concentrator.