The massive deployment of the microgrid concept and active distribution networks will significantly impact power systems and is expected to bring various technical, economic, and environmental advantages, but also many management and operational challenges.
Advantages of microgrids
The development of the microgrid concept is very promising for the electric power industry as a number of advantages can be foreseen at several levels.
Advantages of microgrids are:
Reduction of both physical and electrical distance between generating units and loads may contribute to
- Improvements of reactive support of the whole system, thus enhancing the voltage profile.
- Reduction of transmission and distribution feeder overload.
- Reduction of transmission and distribution losses.
- Reduction/postponement of investments in the expansion of transmission and large‐scale generation systems.
Power quality issues
Improvement in power quality and reliability, in particular, is achieved because of
- Better match of supply and demand, especially when involving micro‐combined heat and power units.
- Reduction of the impact of large‐scale transmission and generation outages.
- Minimization of downtimes if micro sources are allowed to operate autonomously making use of the control capabilities of the microgrid that involve the management of micro sources, loads, and storage.
- Improvement of voltage profiles, in case of under‐ and overvoltages, if micro sources are allowed to regulate the voltage at their connection point through their power electronic interfaces either locally or using a hierarchical control approach.
The following advantages can be attained
- The possible development of market‐driven operation procedures of microgrids will lead to a significant reduction of market power exercised by established generation companies because the microgrid acts as an aggregator for individual loads and microgeneration units, enabling them to participate in electricity markets.
- Microgrids may be used to provide ancillary services, namely, load‐frequency control and local voltage support.
- Widespread application of modular microsources may contribute to a reduction in energy price in the power market with an appropriate economic balance between network investment and distributed generation utilization.
The environmental impact of micro sources is expected to be smaller than with large conventional thermal power stations. There are two main benefits of the microgrid in this topic:
- Physical proximity between consumers and micro sources might help increase consumer awareness toward a more rational use of energy.
- The reduction of greenhouse gas (GHG) emissions could mitigate the alleged effects of climate change due to the creation of technical conditions to increase the connection of RES at the LV level.
Disadvantages of microgrids
Several challenges and potential drawbacks face the development of microgrids as follows:
These technical barriers are mostly related to the relative lack of experience and technical knowledge to operate and control a significant number of micro sources, which require extensive real‐time and offline research on issues such as management, protection, and control of microgrids. Also, specific telecommunication infrastructures and communication protocols must be developed to help manage, operate, and control the microgrids. However, some of these technical difficulties are in the way of being overcome as more research and demonstration projects are being set up across Europe, the United States, and Asia.
The high installation cost for microgrids is a big disadvantage that may be reduced if some form of subsidy from government bodies is obtained to encourage investment, at least for a transitory period, given the current official environmental and carbon capture goals.
As this is a comparatively recent area, standards are not yet available for addressing power quality, operation, and protection issues, for instance. This constitutes a serious obstacle to the massive deployment of microgrid technologies.
In some countries, there is a lack of legislation and regulations for the operation of micro sources. However, in Portugal, for instance, there is already specific legislation addressing the connection of microgeneration to the grid that establishes the tariffs to be paid to microgeneration, adopting an avoided cost strategy leading to subsidized tariffs.