Design, testing, and commissioning of an IEC 61850-based substation automation system

IEC 61850-based substation automation

The transmission substation serves as a fundamental element inside an electrical power system, specifically engineered to ensure the reliable and efficient transfer of power. The implementation of modern smart grid technologies has prompted utilities and vendors to enhance transmission substations through the utilization of substation automation systems that rely on novel protocols and established smart engineering methodologies.

This study elucidates the authors’ expertise in the realm of designing, testing, and commissioning a substation automation system (SAS) based on the IEC 61850 standard. This study aims to comprehensively discuss key elements of contemporary SAS, encompassing fundamental knowledge and optimal methodologies derived from extensive practical expertise.

Section II provides a concise explanation of a Substation Automation System (SAS). The explanation of the SAS components may be found in Section III, which is then followed by an overview of the major and minor communications protocols in Section IV.

In the subsequent sections, Section V provides an in-depth analysis of a resilient communications network, while Section VI delves into the many aspects pertaining to cybersecurity. Sections VII and VIII of the document provide an explanation of the rationale behind substation automation, as well as an overview of HMI visualization.

Substation Automation System Overview

The integration of intelligent electronic devices (IEDs) and a communications network for the purpose of monitoring and controlling automatic substations is commonly referred to as a Substation Automation System (SAS).

The purpose of this system is to provide both local control within the substation and remote control from utility load dispatch centers or load control centers. Figure 1 depicts a simplified block diagram illustrating the structure of a transmission SAS.

Figure 1 – Block Diagram of Substation Automation System (SAS)

Where:

1. Includes circuit breakers, transformers. CTs and PTs. actuators. sensors. etc.
2. Includes bay control units. protective relays. station I/O, time servers. and all IEDs.

Substation Automation System Components

1. Servers with SCADA

The utilization of robust computer systems equipped with SCADA applications is a common practice in the field of power systems. These systems are responsible for establishing communication with Intelligent Electronic Devices (IEDs) in order to facilitate the monitoring and control of the power system.

1.1 Database Server (DB)

The primary SCADA application software is installed on the database (DB) server. The device establishes communication with the intelligent electronic devices (IEDs) present in the operational area in order to collect data and transmit control commands. The data encompasses real-time analog values, indications, alerts, controls, and set points.

Moreover, the quantity of superfluous collections of database servers can be augmented in accordance with the quantity of voltage levels and intelligent electronic devices (IEDs).

1.2 Gateway Server

The gateway server, also known as the GW server, assumes the responsibility of facilitating communication beyond the substation boundaries. Its primary function is to establish a connection with a master station, enabling the centralized management of all substations within a defined geographic region. The configuration of the SCADA application database is likewise implemented within the GW server.

The GW server has a crucial role; it is vital that another redundant machine be provided as backup. However, both GW servers always communicate with the field. The master station performs the redundancy by choosing which GW server to communicate through. In other words, both GW servers are configured as master-master (hot-hot).

Figure 2 below illustrates a standard configuration of DA and GW servers within the context of SAS.

Figure 2 – DA and GW Servers in an SAS Network

2. Network Components

The primary network components of a Supervisory Control and Data Acquisition (SCADA) system are industrial-grade managed Ethernet switches and a redundancy box.

1. Managed Ethernet Switches

These devices are network switches that can be configured to link all parts of an SAS to a network and send and receive data in accordance with the system’s needs. These are multiport devices having per-port configuration flexibility.

Managed Ethernet switches are distinguished by their VLAN awareness and support for the Rapid Spanning Tree Protocol (RSTP).

2. Redundancy Box

This component is typically installed in substations that use the IEC 62439-3 Parallel Redundancy Protocol (PRP) for their communications infrastructure. A redundancy box provides a backup line of communication between a PRP-based network and IEDs and devices with only a single network interface that are not PRP-compliant.

3. Intelligent Electronic Devices (IEDs)

An IED is a very versatile smart device used for protection, automation, monitoring, and control in power system automation. With SCADA serving as an intelligent interface for field devices in an IEC 61850 setting, each IED is capable of conducting autonomous communications.

4. Workstations

The grid operators have access to two primary workstations where they can do regular maintenance and carry out operational tasks.

4.1 Operator Workstation (OW)

The database servers can be accessed through this machine’s graphical user interface (GUI). Since there is no direct connection between the OWS and the IEDs in the field, the IEDs completely rely on the consistency of the data stored on the DB servers.

The OWS is set up to work with just the primary database server.

4.2 Engineering Workstation (EW)

All substation equipment can be accessed through the engineering workstation (EWS). It is the responsibility of the EWS to configure and update the Substation Configuration Description (SCD) files and IED configuration parameters for all IEDs in the substation. It is unable to carry out SCADA functions.

Because it can connect to any IED in the substation, this computer needs strict security.

5. Satellite Clock for Time Synchronization

In order to accurately analyze data collected across any distributed control system or network, time synchronization plays a critical role in SCADA applications. In order to synchronize the time, a dedicated Simple Network Time Protocol (SNTP) server is set up so that it may collect accurate time from GPS and GLONASS satellites.

There are benefits to setting up an SNTP server. Because it operates on the same local-area network (LAN) that IEDs do, it helps keep physical-layer installation costs down.

Inter-Range Instrumentation Group (IRIG)-based protocols are also utilized for mission-critical applications that demand the highest possible precision.

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