Digitalizing regenerative power plants – managing energy intelligently

The share of renewable energies in the electricity supply is rising and regenerative power plants such as large PV power plants or battery-storage systems are increasingly coming to the fore in the energy industry. With the SMA Power Plant Manager, these decentralized energy systems do not only meet all the requirements of grid operators, but are also optimally prepared for new energy marketing models.

If, in the past, the task of regenerative power plants principally consisted of generating inexpensive and sustainable electricity and feeding it into public energy grids, today they must also satisfy the requirements for comprehensive grid support and efficient integration of energy storage systems and consumers, as well as digital networking and cyber security. The SMA Power Plant Manager is based on ennexOS, the trendsetting IoT platform for cross-sectoral energy management, and prepares regenerative power plants for all the requirements for decentralized and hybrid energy generation as well as flexible energy marketing.

The SMA Power Plant Manager networks regenerative energy generators to form a single system.

The reliable control gear for PV farms is responsible for the entire power and energy management for PV power plants with or without a battery-storage system, for grid-coupled large-scale storage systems, PV diesel systems and complete microgrids (stand-alone grids). Together with battery inverters from SMA featuring grid-forming functions, even conventional power plant functions such as black starts of PV power plants and automatic grid synchronization as well as a backup power supply can be provided. To date, more than 300 regenerative energy systems larger than 5 gigawatts around the world already use an SMA solution for farm control.

Flexible farm control

Thanks to the flexibility of the SMA Power Plant Manager, new individual and project-specific requirements for the grid-compliant open- and closed-loop control of regenerative power plants can be met quickly and reliably. These include the following:

• Highly dynamic closed-loop control of active and reactive power to comply with the regulatory requirements for grid connection and for efficient operation of the power plant
• Grid support through voltage and frequency stability
• Energy generation according to external setpoints and/or stored characteristic curves
• Adherence to predefined schedules for active and/or reactive power
• Precise measurement and recording of the grid status (voltage, current, frequency, active/reactive power, etc.) with integrated measurement modules or external measuring devices or power analyzers
• Special grid synchronization modules for connecting microgrids to, and disconnecting them from, the utility grid

The SMA Power Plant Manager is the central unit for the complex management of regenerative power plants.

New business models and marketing options

On the changing energy markets, the focus is turning to new business models and energy marketing options. The SMA Power Plant Manager is ideally prepared for that and offers operators of regenerative power plants numerous possibilities that help optimize energy marketing. Thanks to its intelligent energy management, especially in combination with SMA battery inverters, better market prices can be achieved, energy supply contracts can be adhered to precisely, grid management services can be provided and expensive peak loads can be avoided.

Balancing energy

The provision of balancing energy is a business model that is already coming into play in a number of markets. The largest European battery-storage power plant that is responsible for providing balancing energy is located in the county of Hertfordshire in Great Britain. It provides the operating reserve necessary for frequency control in order to thereby compensate for grid fluctuations and ensure the supply of electricity to industry, businesses and households. 26 battery inverters from SMA integrate the modern battery-storage system with lithium-ion technology into the utility grid. The SMA Power Plant Manager controls the energy and power management for such business models and optimizes utilization of the power plant.

Stand-alone grids

In conjunction with large-scale battery-storage systems, regenerative power plants can supply complete stand-alone grids, without any need to fall back on the use of diesel generators. For example, the energy supply to the Caribbean island of St. Eustatius is provided largely by clean solar power during the day. This is ensured by the intelligent energy management for the PV diesel hybrid system from SMA. When there is sufficient renewable energy available, the system automatically switches the diesel generators off. The utility grid is then supplied by the SMA Sunny Central Storage battery inverters alone, without affecting the island’s energy supply. This system function guarantees maximum savings on fuel and harmful emissions.

PV-Diesel-Hybrid system on the Carribbean island St. Eustatius.

Black start

SMA Power Plant Manager.

In addition, regenerative power plants with SMA battery inverters can enable black starts of complete energy systems, for example, after a power outage. The Power Plant Manager starts and controls the battery inverters, increases the voltage and synchronizes the sub-grid with the supply grid automatically until the two grids can be connected. It is also possible to use the backup power supply in stand-alone mode.

Selling

For operators of large solar or hybrid power plants, the SMA Power Plant Manager makes it easier to sell electricity. For profitable exchange trading on the short-term-oriented spot market in day-ahead or intraday trading, accurate forecasts and the reliable delivery of the agreed amounts of electricity are indispensable. These enable the best possible market prices to be achieved and the agreed schedules for the supply of renewable energies to be precisely adhered to. The Power Plant Manager controls the energy flows of the system in line with requirements and provides various options for connecting to superordinate management systems via standardized communication protocols such as Modbus, IEC 60870-5-104 or DNP3.

Virtual power plants

Visualizing all energy flows in Sunnny Portal.

The SMA Power Plant Manager integrates decentralized, regenerative power generation systems into virtual power plants through its flexible interfaces. At the moment, PV systems, generators and electricity storage systems are supported. The Power Plant Manager is already prepared for future expansion to include biogas, wind energy, cogeneration or hydroelectric power plants as well as electrical appliances and power-to-gas or power-to-heat systems. The coordinated control of the generation plants and battery-storage systems means that the energy can be sold in the best possible way and that grid expansion can also be avoided where applicable.

Clear visualization – quick overview – reliable updates

Monitoring a PV Power plant.

On clear dashboards and on the basis of graphical evaluations, the SMA Power Plant Manager enables information about measured values from the power plant, setpoints for grid management services and feed-in management requirements that is exact to the second to be shown and accessed throughout the system. The option to parameterize the SMA power plant components plant-wide saves time during commissioning and maintenance. All events in the power plant are logged with a precise timestamp. As a result, failure causes can be quickly localized, traced and rectified. Via secure device software connections, power plant operators can also keep track of the efficiency of the complete energy system in Sunny Portal, the professional monitoring solution from SMA, on clear dashboards and with comprehensive analysis tools at all times. Besides the easy administration of the entire power plant portfolio, prompt technical support from SMA experts is guaranteed whenever it is required. Regular software updates – installed automatically upon request – provide new functions and ensure the safe operation of the plant.

Simulated reality

With SMA Engineering Services, supported by the SMA Power Plant Manager, planners of PV and/or hybrid power plants receive the best possible assistance when it comes to planning a plant or designing a system – including through the provision of simulation models (e.g., PSCAD, PSS/E). These provide a 1:1 representation of how the devices will operate in reality. This is made possible by embedding the source code of the device software directly in the models. As a result, all parameters of the devices can be shown exactly and set. Thus, the electrical behavior of the power plant at the point of common coupling can be accurately predicted and individually optimized. This enables risks in the implementation of the project and on acceptance of the plant to be reduced significantly in advance.

Unique experiment

An exciting example of a backup power supply that regenerative power plants can provide is an experiment that was carried out last year in the northern German municipality of Bordesholm. Last December, Bordesholm became the first town in Germany to completely disconnect itself from the public utility grid for an hour. During this time, the electricity supply relied exclusively on renewable energies from photovoltaics, biomass plants and combined heat and power plants as well as from the battery-storage system. The control gear for PV farms supplied by SMA controlled all of the energy flows and regulated the frequency and voltage both before and after the changeover under load without any problems, and all without any impact on the energy supply to the loads in the grid area.

A 10-megawatt battery-storage system with a capacity of 15 megawatt hours and provided by project developer Renewable Energy Systems (RES) was commissioned in Bordesholm in early 2019. The storage system’s main job is to deliver a frequency containment reserve, but it also supplies electricity for direct selling and safeguards the electricity supply in the event of a grid failure. SMA supplied a coordinated system solution for the project equipped with stand-alone mode, black start, synchronization and backup power supply functions.

First publication in German in ew – Magazin für die Energiewirtschaft.