**2.1 Renewable energy grid integration**

Like any other form of generation, renewable resources such as wind or solar power will have an impact on power system reserves and will also contribute to a reduction in fuel usage and emissions. In particular, the impact of wind power not only depends on the wind power penetration level, but also on the power system size, geographical area, generation capacity mix, the degree of interconnection to neighboring systems and load variations.

Some of the major challenges of renewable energy integration need to be addressed in the following main areas:


With increasing penetration and reliance on renewable resources have come heightened operational concerns over maintaining system balance. Ancillary services, such as operating reserves, imbalance energy, and frequency regulation, are necessary to support renewable energy integration, particularly the integration of intermittent resources (Chuang & Schwaegerl, 2009). Without supporting ancillary services, increased risk to system imbalance is introduced by the uncertainty of renewable generation availability, especially in systems with significant penetration of resources powered by intermittent supply, such as wind and solar.

In recent years, energy systems whether in developed or emerging economies are undergoing changes due to the emphasis of renewable resources. This is leading to a profound transition from the current centralized infrastructure towards the massive introduction of distributed generation, responsive/controllable demand and active network management throughout the smart grid ecosystem as shown in Figure 1. Unlike conventional generation resources, outputs of many of renewable resources do not follow traditional generation/load correlation but have strong dependencies on weather conditions, which from a system prospective are posing new challenges associated with the monitoring and controllability of the demand-supply balance. As distributed generations, demand response and renewable energy resources become significant portions of overall system installed capacity, a smarter dispatch system for generation resources is required to

One method to cope with uncertainties is to create a better predictive model (Cheung et al., 2010, 2009). This includes better modeling of transmission constraints, better modeling of resource characteristics including capacity limits and ramp rates, more accurate demand forecasting and external transaction schedule forecasting that ultimately result in a more accurate prediction of generation pattern and system conditions. Another method to cope with uncertainties is to address the robustness of dispatch solutions (Rios-Zalapa et al., 2010). Optimality or even feasibility of dispatch solutions could be very sensitive to system uncertainties. Reserve requirements and "n-1" contingency analysis are traditional ways to ensure certain robustness of a given system. Scenario-based (Monte-Carlo) simulation is another common technique for assessing economic or reliability impact with respect to uncertainties such as renewable energy forecast. These methods and techniques are

necessary as the industry integrates renewable energy resources into the power grid.

Like any other form of generation, renewable resources such as wind or solar power will have an impact on power system reserves and will also contribute to a reduction in fuel usage and emissions. In particular, the impact of wind power not only depends on the wind power penetration level, but also on the power system size, geographical area, generation capacity mix, the degree of interconnection to neighboring systems and load variations. Some of the major challenges of renewable energy integration need to be addressed in the

With increasing penetration and reliance on renewable resources have come heightened operational concerns over maintaining system balance. Ancillary services, such as operating reserves, imbalance energy, and frequency regulation, are necessary to support renewable energy integration, particularly the integration of intermittent resources (Chuang & Schwaegerl, 2009). Without supporting ancillary services, increased risk to system imbalance is introduced by the uncertainty of renewable generation availability, especially in systems with significant penetration of resources powered by intermittent supply, such as wind and solar.

cope with the new uncertainties being introduced by the new resources.

**2. Challenges of smart grid** 

**2.1 Renewable energy grid integration** 

Design and operation of the power system

System adequacy and the security of supply

Connection requirements for renewable power plants

following main areas:

Grid infrastructure

Electricity market design

For the purposes of balancing, the qualities of wind energy must be analyzed in a directly comparable way to that adopted for conventional plants. Balancing solutions involve mostly existing conventional generation units (thermal and hydro). In future developments of power systems, increased flexibility should be encouraged as a major design principle (flexible generation, demand side management, interconnections, storage etc.), in order to manage the increased variability induced by renewable resources. Market design issues such as gate-closure times should be reduced for variable output technologies. The real-time or balance market rules must be adjusted to improve accuracy of forecasts and enable temporal and spatial aggregation of wind power output forecasts. Curtailment of wind power production should be managed according to least-cost principles from an overall system point of view.
