Smart energy systems of cities with an active-adaptive network (Smart Grid): now and future

The topics of intelligent energy systems of cities, active-adaptive networks, digitalization of energy systems and substations are increasingly being raised for discussion at thematic platforms, forums and meetings at various levels. The importance and prospects for the development of intelligent energy systems are emphasized by the published "Roadmap" "EnergyNet" of the national technology initiative and the active construction of digital substations by network companies in recent years.

Despite this, there are still many related issues with the architecture, implementation, relevance of intelligent energy, and in this regard, it is interesting to hear the opinions of not only legislators, but also manufacturers and integrators of solutions and equipment. Today we discussed these topics with the executive director of "Electronmash" JSC Andrey Litvinenko.

- The topic of intelligent active-adaptive energy networks is increasingly being raised at various levels today. In your opinion, how relevant and in demand are active-adaptive energy networks in cities?

– In order to understand what intelligent energy systems of cities with an active-adaptive network are, I suggest that we first take a broader look at the question: what are intelligent city systems in general, without reference only to energy?

To do this, we need to imagine a future in which all of these systems already exist. In this future, cities have created and operate intelligent electric grids, intelligent heating grids, water and gas supply networks, intelligent ground transportation and subway, intelligent emergency services, intelligent services, even buildings are intelligent. All of these urban areas exchange relevant information with each other in real time through a single city management system. For example, a failure in the subway automatically affects the scheme and intervals of ground transportation, and a power line shutdown leads to an automatic change in the district's power supply scheme. The city authorities and the population also receive relevant information from this city management system, the former - to improve management efficiency, the latter - to provide timely information and receive services.

In general, the operation of such a system leads to the existence of a self-regulating city network, in the life of which both the government and residents participate, as they say, "in real time." Receiving feedback from the population allows for timely adjustments to the algorithms of self-regulating systems, thereby continuously increasing the efficiency of city services. The electric network of such a city itself is also actively adaptive, that is, capable of changing and adjusting to the processes occurring in it, in order to maintain an uninterrupted power supply in optimal modes. Mutually complementary participants in such a network are generation sources (both traditional and renewable), trunk and city electric networks with their substations, as well as consumers, both with their own generation sources capable of supplying excess power to the network, and without them.

For the automatic operation of such a network, in addition to the city control center, which enters control commands at the global level, local (nodal) control centers are needed, on which the daily operation of individual network segments depends.

An active-adaptive power grid, or Smart Grid in some sources, is a self-regulating system for providing energy to a city. It provides: analysis of energy consumption by individual consumers and groups, accumulation of energy in case of excess generation and its release to the grid in case of a power deficit, automatic reconfiguration of the power grid in emergency situations, automatic reconfiguration of protection and automation devices depending on the modes, informing related systems about events occurring in the grid.

– What objects are participants in an active-adaptive power grid? Which of them exist in traditional grids and are they ready in their current form to work as part of an active-adaptive grid?

– I would divide all participants in an active-adaptive grid into three groups according to the degree of their presence in traditional grids and the level of their readiness to work as part of an active-adaptive grid.

The first group is traditional generation, intersystem and trunk grids. The participants of this group are an integral part of today's electrical network and have a high degree of readiness for operation as part of an active-adaptive network. At the facilities of this group, such systems as emergency and technological automation, telemetry and automated process control systems, relay protection and automation have been actively operating for quite a long time.

The second group includes consumers without generation sources, and city networks that supply these consumers, and here we can also include nodal control centers. This group also exists in today's networks, but its elements are not fully or partially ready for operation as part of an active-adaptive network. This is due to the fact that city electrical networks have always been built on the basis of simple and inexpensive equipment. On the low side of city substations, protection, as a rule, was built on fuses, so it is impossible to talk about remote control and automatic changes in some operating parameters of city networks in their current form. Therefore, equipping city substations with intelligent devices alone is not enough here - a comprehensive reconstruction is required with the replacement of the main electrical equipment with supporting remote and automatic control. Almost the same situation is on the side of end consumers: the maximum that is transmitted to the energy supply organization in an automated form today is the readings of commercial metering data. Therefore, today consumers do not have the opportunity to influence the operation of the power grid depending on the processes that occur in the consumers themselves.

Renewable generation, consumers with mini- and microgeneration sources, and the City Control Center are the third group of participants in the active-adaptive network, which is practically absent today. Solar and wind power plants being built in Russia today are not equipped with energy storage systems, so they are not capable of accumulating energy during peak production hours and supplying it to the network during power failures, and consumers with low-power solar panels or a wind turbine do not have the legal ability to supply excess generation to the network. These aspects do not allow for the construction of decentralized active-adaptive power supply systems operating using energy blockchain technology - a system that manages several trading agreements between consumers who purchase excess generated electricity directly from the original producer without additional costs and a trade markup that quickly changes the cost of this electricity depending on needs and the volume of surplus. Thus, the cornerstone in this group of participants of the active-adaptive network is the storage of electric energy, or rather their absence in the composition of renewable generation.

– What equipment makes a passive electric network actively adaptive?

– Currently, the functioning of any existing energy system is based on the principle of balance of generated and consumed electric energy at each moment in time, regardless of the scheme of the existing network, thus, the accumulation of excess electric energy during consumption dips is not provided.

The appearance of electric energy storage in the networks will stabilize the operating modes of generation sources: during hours of consumption dips, accumulation will be carried out, and during hours of peak consumption, the storage devices will issue deficiencies of electric energy to the network.  In an ideally balanced situation, the generators will work around the clock in the nominal mode.

With regard to renewable power generation sources (wind power plants, solar power plants, etc.), joint operation with energy storage devices is particularly relevant, since it allows for the stable supply of electricity to the grid, including at night (sun power plants) and in windless weather (wind power plants), without the need to use traditional thermal power plants to cover short-term power imbalances.

Another important aspect of the active adaptive network is the ability to regulate reactive power. In the case of solar or wind power plants, the voltage converter used in their composition is capable of not only compensating for reactive power, but also supplying it to the network with virtually no time delays. But what about other networks operating from traditional generation sources?

In existing networks, VCCS and shunt reactors are used for compensation purposes, while synchronous compensators are used at power plants. Each of these devices has its own advantages and area of ​​application, but the disadvantages of these devices are a small discrete regulation zone (VCCS and shunt reactor) or high inertia (synchronous compensator). For operation in active adaptive networks, it is advisable to use modern solutions - static reactive power compensators based on converters (STATCOMs).

STATCOMs are capable of instantly compensating reactive power at the connection point, improving the static and dynamic stability of the power system. In addition, the use of STATCOMs allows automatic regulation of the voltage level in network nodes in normal and emergency modes, ensures asynchronous communication between two power systems, and reduces losses in overhead lines. In order to automatically reconfigure the power supply network and/or protection and automation devices depending on the modes, substations operating as part of an active-adaptive network must be digital.

– Do substations for such a network necessarily have to be digital?

– This is the right question to ask yourself in the modern world, since the assertion that all substations must become truly digital to build an active-adaptive network is not entirely correct. Steps to create digital substations have been taken in Russia for more than ten years, and the substations created during this period certainly cannot be considered fully digital, rather they are conditionally digital, in which IEC 61850 GOOSE and MMS are used, but nevertheless these substations can already now become full-fledged participants in an active-adaptive network. The life cycle of any substation is at least thirty years, in fact, they work for forty to fifty years, and somewhere even more, in connection with which it is very important that the ideological decisions laid down when creating a network of such substations allow in the future not only to use, but also to expand those technologies that are now in the stage of active development and testing on real objects.

The question of whether or not to build a particular substation in digital form must be resolved comprehensively, within the framework of a network enterprise and taking into account the future development of the network. For example, if you build one digital substation in each network enterprise, you will solve the issue of personnel gaining experience working with a digital substation, but in general the networks of these enterprises will not become actively adaptive, since the very concept of a network implies the interaction of substations with the same functionality. At the same time, a digital substation will sparkle with new properties as soon as a network of such substations appears. It is no secret that the cost of a digital innovative substation is now more expensive than a conventionally digital one due to the fact that innovative technologies are fully reserved for classical ones.

At the same time, conditionally digital substations using IEC61850 GOOSE and MMS have long been commonplace; when constructing such substations, they no longer play it safe and do not back up these solutions with classic connections. That is why the use of conditionally digital substations allows for the digitalization of technology at the level of not just individual substations, but entire network areas, in order to ensure the operation of active-adaptive networks in real time without excessively increasing the cost of construction. Here, it is worth noting the interesting experience of large industrial enterprises, which are currently less inclined towards active-adaptive networks or towards building digital substations in the full sense of the word. However, these enterprises are already actively laying down equipment with remote control capability and support for IEC61850 GOOSE and MMS protocols to ensure future expanded network management functions, the implementation of emergency unloading of process units, all kinds of logical protection, monitoring the state of power supply equipment and ensuring repairs based on the actual condition.

– What equipment can Electronmash offer for digital substations designed to operate as part of an active-adaptive network?

– Working in various segments of the electrical equipment market, from energy to oil and gas production, oil and gas processing, we have developed and successfully supply our customers with a full range of equipment of our own manufacture, capable of operating as part of digital substations, and engineering services provided for complex supply guarantee full compatibility of the component base and the optimal ratio of the required functionality and cost of the equipment.

The key to any successful implementation in the supply of equipment for digital substations is, first of all, competent engineering solutions. They include the selection of the optimal component base, proven by many years of operating experience, as well as carefully executed engineering work on the creation of working design documentation. No less important is the execution of all operations on parameterization of this equipment and complex adjustment as part of a digital substation directly at the manufacturer's plant - this guarantees the customer minimal time and financial costs at the facility.

Digital substations impose a large number of requirements and features on the execution of equipment, for example, the requirements for ensuring the own needs of substations, namely, for operational direct current systems, increase significantly. That is why in 2016 special attention was paid to the development of a scalable line of "ExOnSys" DC systems with an advanced diagnostics and monitoring system for charging and rectifying devices and batteries.

We have developed fully motorized 6-10 kV switchgear "Eltema" and 35 kV switchgear "Eltema +" to provide the ability to automatically reconfigure power supply circuits. Switchgears are used at the 6-35 kV level,  with control of circuit breaker drives, cassette-slide elements and earthing knives. Such modifications are already in high demand and are mass-produced both for installation in customer substations and as part of digital indoor switchgear, when the customer receives a building fully equipped with auxiliary systems, including the power supply system, with 6-10-35 kV switchgear cabinets and network communications cabinets installed and adjusted at the factory. This approach ensures the integration of the indoor switchgear into the facility at the level of exchanging parameterization data files.

Thus, answering your question, we would like to emphasize that Electronmash JSC is a full-cycle enterprise ready to provide the full range of works on creating a turnkey digital substation, including the development of working documentation, equipment manufacturing, installation, commissioning and commissioning to the customer.

– What are the risks associated with the transition of the energy sector to “digital rails”?

– The issue of the emergence of risks during the transition of the energy sector to “digital rails” is quite comprehensive, and many professional organizations working in this area are dealing with it, however, in any case, in order to implement actively adaptive networks, it will be necessary to carry out a huge legislative work, improve devices and equipment, train personnel of a new format capable of designing, building, commissioning and operating new generation networks and manufacturing equipment for work in their composition. Of course, in Russia such work is being carried out in network companies and leading scientific and technical centers, within the framework of specialized CIGRE committees and, most importantly, with the involvement of equipment manufacturers. The qualifications of our specialists and their practical experience allow us to actively work with developers and ideologists of standards and make our own contribution to the general movement towards the digital future, and our material and technical base allows us to test these innovations, interpreting them directly in equipment, standard documentation, and offering them to the energy community.