Smart grid can enhance legacy electric systems (i.e. the traditional electricity infrastructure) by improving reliability and security; additional smart grid can offer economic benefits and cost savings, environmental improvement, and so forth.
Generally smart grid represents the integration of digital technologies, sensors and other information and communication technologies to enable more efficient and reliable electricity management and utilization. Smart grid technologies (both hardware and software) include those which the consumers interact with, and those in transmission and distribution. In this article we look at some of the key technologies that can be used to achieve smart grid objectives. We will discuss these technologies under 6 sections:
Contents
A grid-tie inverter (GTI) is a special type of inverter used for integrating renewable energy sources e.g. solar photovoltaic (PV) with the grid. GTI converts DC electricity into AC. Note, renewable generation from say solar PV produces DC electricity, and this must be converted to AC before being fed to the grid for transmission.
Generally large-scale wind parks, solar PV arrays or concentrated solar-thermal projects connect directly to the high-voltage transmission grid.
Rooftop solar photovoltaic (PV) and small-scale wind turbines also connect directly to the low-voltage distribution grid, which is normally operated by the local utility.
Renewable generation from solar PV or wind turbines produces DC electricity. The grid transmits and distributes AC electricity for use in homes and for industrial consumption. The efficient conversion of DC power to AC is required to enable more renewable generation to contribute to the electricity system for both the high-voltage transmission and the low-voltage distribution network. Using the grid-interactive inverter, electricity generated from small-scale renewable technology like solar and wind, that is not utilized on-site can be sold back to the utility’s distribution network and compensated either through net metering or feed-in tariffs.
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The grid-tie inverter (GTI) includes an oscillator that synchronizes the frequency of the renewably generated electricity to that of the grid. Additionally GTI is used to disconnect from the grid if the electricity in the grid is disrupted. This safety function prevents electricity from flowing in the downed grid system while repairs are made; however, it also implies that homes or businesses with solar PV cannot use the generated power until the system is back online.
The synchrophasor or phasor measurement unit is a very important smart grid technology that assists in enhancing the transmission component of the electricity system. The synchrophasor measures conditions on transmission lines through assessment of AC sinusoidal quantities (voltage, angle, and frequency), synchronized in time. With a fixed temporal reference frame, synchrophasor measurements can be used to monitor power flow and potentially create automatic adjustments when disruptions are identified, creating the possibility for what is referred to as ‘self-healing’ grid. This type of monitoring also offers system operators the ability to observe the grid’s overall condition (referred to as “wide-area situational awareness”), including the capacity to balance power flows, report outages and receive weather, demand and performance data in almost real time.
As one of the key smart grid software, Power Transmission Analysis Software is a set of tools to configure customized power transmission system models that are almost same as real world transmission systems to improve transmission system management. This type of software offers a powerful tool to enable electrical engineers to model, design and manage transmission networks. An Example of this software include: Power System Simulator for Engineering from Siemens.
Energy management systems (EMS) are used by utilities to monitor, control, manage and optimize electricity generation and transmission. SCADA (Supervisory Control and Data Acquisition) which is a typical subcomponent of EMS is centralized control system that facilitates smarter communication and information flow between electricity generators, utilities, and consumers. SCADA in this case represents monitoring and control components and EMS refers to the generation control and scheduling and the overall networked system. Even though SCADA forms part conventional electric systems, it is considered an important component of smart grid technology.
Outage management systems (OMS) that are designed to identify (identifies real-time outages & location of the outages), resolve outages and provide historical data on past outages form an important component of a smart grid. OMS presently can provide real-time web-based outage information to consumers through their utility’s website.
Modern technologies that enable higher-voltage, higher-efficiency transmission of electricity from generation substation to distribution grid form part of smart grid technology. For instance, flexible AC transmission systems, that is, electronic-based apparatus to control AC transmission system parameters to increase power transfer capability; a key component of this system is technology to stabilize the voltage, to reduce the presence of reactive power on the lines which exists when the current and voltage are not in phase. The volt-ampere reactive (var) is a unit used to measure reactive power in an AC power system, and reactive power compensation or what is referred to as static var compensation (SVC), is used to regulate and stabilize grid voltage. The stabilization function of SVCs is vital to prevent voltage breakdown, particularly when new types of electricity generation such as solar power, wind are added to the transmission system.
Lastly, substation automation applications for voltage control, synchronism, load and bus transfer, load curtailment and fault detection may also be considered as key aspects of smart grid technology.
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Enhancing storage capacity is particularly important when integrating more renewable power sources, because, for instance, peak wind does not usually coincide with peak demand. This has a huge potential for cutting down costs associated with satisfying peak demand and at the same time allowing variable renewable energy to contribute more to meeting baseload demand. All these, help improve efficiency and resilience of the grid.
Battery technology development is on upward trend, and has great potential for energy storage in different types of applications. A variety of large-scale rechargeable batteries are available that can enhance electricity storage.
Other energy storage technologies include: thermal energy storage, in which energy is stored in heat either collected in molten salts or synthetic oil; ultra-capacitor is another technology helpful for backup power during brief interruptions, it stores energy by increasing the electric charge accumulation on its metal plates and can discharge the energy by releasing the electric charge on the metal plates; lastly, superconducting magnetic storage is another storage technology, this device is a winding coil of superconducting wire, changing the current in the wire can add or release energy from the magnetic field. Advantages of this technology include: energy can be stored indefinitely with minimal losses, high reliability and low maintenance because the components are motionless and at steady state the wires release no energy. The only disadvantage of superconductors is that refrigeration is needed.
Smart grid technologies for substation automation enhance networks of communication which improve remote management that offers a number of benefits such as reduced operational and capital expenses, assistance in regulatory compliance and enhanced grid security.
Additionally, key smart grid technologies for distribution networks include distribution automation, FDIR (fault detection, isolation and recovery), and advanced on-load tap-changer (OLTC), that is used for enhanced voltage regulation.
Here, the most important smart grid technology is the smart meter, which helps consumers and utilities manage and monitor electricity consumption. Smart meters, also termed to as advanced metering infrastructure (AMI), allow for two-way communications between households and utilities companies. This improved communication lets utilities companies read the meters remotely, respond more quickly to potential problems and communicate real-time electricity prices, allowing households to adjust their electricity use based on real-time usage and pricing information.
Other smart grid technologies in this section that contribute to demand management include devices such as programmable dishwaters, air conditioners, refrigerators and consumer interface tools like home energy portals, smartphone apps, etc. that allow households/individuals to monitor their energy consumption and manage it.
Related: How Smart Meters Measure, Monitor & Manage Electricity
Technologies such as control system programs for separating the Microgrids from the larger grid under certain circumstances generally referred as ‘islanding’, thus protecting the individual homes or organizations from the grid. Other smart grid technologies include: Geographic Information System (GIS), and protection and control technologies.
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