In many parts of the world energy production from non-traditional renewables such as wind and solar is growing rapidly. For example, the EU has committed to renewable targets of 20% by 2020 and 27% by 2030.
However, such ambitious targets, resulting in growing connections to the MV and LV grids of energy sources that are both intermittent and decentralized, are bringing new challenges for grid operators in terms of maintaining stability and quality and adequacy of supply.
“Renewable energy integration is impacting all levels of the power system – at the local level, at the system-wide level and from a market integration perspective,” Goran Leci, Distribution Automation Systems product manager, ABB, told Engerati in an interview. “At the same time, in some countries renewable systems are also being subject to new and more stringent government regulations and demands on issues such as efficiency and grid support functions.”
But with challenges come opportunities and new distribution automation systems are opening the way for utilities to move towards the future power system with multiple players and multi-directional energy flows.
Distribution automation solutions
“The need for efficient distribution automation systems across the whole energy value chain has never been bigger,” says Leci, commenting that ABB’s offering is intended as a “complete and coherent solution” for automation beyond the substation and across the grid.
Encompassing individual products, engineered packages combining primary and/or secondary and communication equipment and full turnkey solutions, the offering is “aimed to meet any utility’s individual challenges cost efficiently.”
The solutions can be applied to pole-mounted disconnectors and reclosers and load-break switches at the field level; to secondary switchgears and ring main units (RMU) at the substation level; or utilized at the SCADA/DMS level to respond rapidly to the consequences of decentralized energy feed-in. In addition, service and maintenance options are available across the power value chain.
Monitoring, control and measurement
Leci explains that as a first step to the seamless integration of renewables, monitoring is essential.
“Grid automation solutions offer a modular way of providing monitoring, control, measurement and protection to enable rapid detection of complex situations ongoing in the grid and an effective response to the consequences of decentralised energy feed-in,” he says.
Some of the leading utilities confronted with integration of large amount of renewables utilize ABB’s grid automation solution to facilitate the integration in a cost effective way.
System protection and fault management
System protection is ensured with protection relays on pole-mounted reclosers while a novel multi-frequency admittance protection algorithm provides accurate detection and location of faults, even in the case of reverse power flows caused by renewable power infeed.
“Better protection selectivity is required for renewable integration and also ensures increased personnel safety,” says Leci.
A reference utility in Finland, where the solution was installed as part of the smart grid to enhance the reliability of overhead lines experienced fewer and shorter duration outages, boosting customer satisfaction while reducing performance penalties.
Line voltage regulation
Line voltage regulation (LVR) offers a fast and simple low capex solution to increasing the grid hosting capacity at both MV and LV levels, Leci comments. Its advantage to be placed at critical points in the network avoids the need for expensive grid connections allowing more renewable power to be connected to the network. The LVR solution can as well be relocated to respond to grid challenges caused by incremental addition of renewable systems in the grid.
A utility in Germany faced increasing levels of wind power generation and consequent large voltage variations. With installations of LVR systems across the network, the voltage levels are now dynamically controlled within the predefined limits. Similarly, another utility in Switzerland facilitated the integration of a customer’s 134kW solar plant using the same solution.
Leci points out that active control of voltage and power flows is necessary to improve the voltage profile and to reduce energy losses. Options include capacitor banks, power transformers with tap changer and line voltage regulators, managed by a rule-based algorithm.
Advanced DMS and DERMS
Real-time monitoring and control of distributed resources is achieved with an integration of distribution management systems (DMS) and distributed energy resource management systems (DERMS). The goal is to maximize renewable penetration with model predictive voltage control.
“The difference between this solution and the Volt/VAR control solution is that instead of being only reactive, it also allows the utility to be predictive and to mitigate voltage violations,” Leci says.
Distribution automation benefits
Leci says that increased grid visibility provides for a better performance, especially when the grid is challenged by renewable energies. “The network configuration also can be improved and the energy losses reduced. With our experience, footprint and our solutions, ABB is the one-stop shop for distribution automation systems and a supporting partner for utilities dealing with renewable integration.”
To find out more about distribution automation requirements with distributed generation and the products and solutions available, see the Engerati webinar Smooth Renewable Integration Thanks to Enhanced Grid Operation and Safety and In Focus series Renewable Integration - Solar and WInd.