MICROGRIDS FOR KERALA

The emergence of Microgrid-as-a-Service (MaaS) model for energy challenges is being acknowledged globally. Roof Top Solar only provides energy self-sufficiency, while, Microgrids can accelerate social development.

The government of India is expected to firm up a policy on Microgrids by end of 2018. Microgrid development across India is likely to be core to achieving targets under NSM. A pilot programme is being implemented by Jharkhand Renewable Energy Development Agency (JREDA) to electrify 320 households across 11 villages through the development of Microgrids. The works also include turnkey implementation of decentralized distributed SPV power plants along with Power Distribution networks to unelectrified households. Microgrid projects are also attempted in Bihar and UP. Microgrid would also lead distributed energy investments for us. Such innovative business models bring radical changes in Industry.

What is a Microgrid ??

Microgrids can be termed as an energy network infrastructure that includes equipment for energy generation (usually multiple distributed energy resources (DERs)), energy distribution network(s), and energy users/consumers of different criticality levels and profiles. A Microgrid can be formed within premises of a large consumer, say, military establishments, hospitals, university campus etc with different load centres and sources form the electrical network of coordinated control and operation.

Microgrid – Functions, monitoring

Microgrids are implemented to fulfil expectations such as resiliency, economy, security, and CO2 reduction. Each microgrid project varies in size, power and voltage levels, number and type of distributed energy resources as well as the number, type, and criticality of electrical loads, etc. Microgrids can use electricity generated from a wide range of powerful technologies, using both renewable and non-renewable energy resources as fuel. The portfolio of generating  technologies selected for a specific microgrid, which might include renewable energy resources, energy storage systems or any other technologies, present different cost-benefit scenarios

Selecting the optimal technologies is critical to the success of a microgrid project. The controls system must maintain system stability, optimally balance supply and demand and respond in real-time to changes conditions on the central power grid.

Monitoring is also an important consideration for microgrids. A microgrid operator may want to monitor a wide range of potential parameters, including voltage, frequency, real power, reactive power, current, switch status points and relay status points. A defining characteristic of any microgrid is its ability to island.

Design engineering challenges

Below is a list of the main calculations and studies to perform.

1. Identification and detailed description of the operating philosophy with all the operating modes of the microgrid.

2. Load flow calculations in all possible operating configurations: The goal of this iterative work is to evaluate the current flows and the voltage levels in the microgrid's power system while in operation.

In microgrids, establishing a relevant load list and assessing the load criticality levels and load consumption profiles are sometimes a challenge.

3. Short-circuit current calculations: The goal is to determine the minimum and maximum short-circuit current levels that may occur in the power system in case of a fault. Those short-circuit current values allow for: the correct sizing of power system equipment in terms of thermal and dynamic current withstand ratings. In microgrids, short-circuit currents are likely to vary substantially between different operating configurations, due to their multi-source design.

4. Protection philosophy and coordination study: Considering the low and variable short-circuit currents of microgrids, the protection study is a key engineering step.

5. Neutral earthing system management: Because electrical installation rules are often specific to local regulations, the management of how the neutral is connected to earth then distributed within the microgrid can become challenging.

6. Dynamic stability studies: It is very important to evaluate, predict and monitor the dynamic behaviour of the micro grid’s power system with regards to transient events.

7. Electrical equipment specifications and single line diagram (SLD).

8. Microgrid control systems: The microgrid control systems are an essential element to make microgrids fully operational. From the detailed description of the operating modes, functional analysis, complete development then configuring the microgrid control system is required.

9. Energy management settings: The same energy models that have been used in the preliminary design can be reused to perform more detailed work and services.

10. Microgrid testing and commissioning: A comprehensive testing and validation specification shall also be written to check that in an actual situation, the microgrid controller provides the expected behaviour and decision based on the selected criteria and the actual constraints. Interoperability with upper–and lower–layer systems must be specified and tested prior to going live.

In Kerala, we can identify large Hospitals, Universities, Commercial complexes etc which can be brought under a microgrid. However, we need a  policy enforcement from the regulators for the purpose.

For more details: Soura Natural Energy Solutions Pvt Ltd