INTRODUCTION

This master thesis has been prepared at DTU Wind Energy Department at the Technical University of Denmark in fulfillment of the requirements for acquiring the DTU Wind Energy Master diploma.
The supervisors for this master thesis have been professor Poul Ejnar Sørensen and researcher Kaushik Das, both from DTU Wind Energy Department.
The external supervisor for this master thesis has been professor Henrik Stiesdal from Stiesdal A/S company.

ABSTRACT

During the last two decades we have seen how the renewable energy sources have been expanded all around the world evolving hand in hand because of the increase of envi- ronmental conscious market acceptance. These renewable energy sources have a great challenge which is the inherent variability as they have stochastic renewable power generation.
The unreliability of wind and solar photovoltaic to generate the energy demanded is the main reason for including energy storage technologies so that we gain dispatchability of WPPs and PVPPs. Energy storage systems have a really special advantage in this sense, as they can shift energy generation to later periods with higher electricity prices and energy demand.
We are living really interesting times if we talk about hybrid wind and solar with energy storage systems and I’m pretty sure they’re going to be crucial in the near future, and so that this can happen, integration of several energy storing within the hybrid and solar pv plants is key to boost penetration of these technologies into the energy market.

INDEX TERMS

CorRES DTU software, time series, hybrid wind and solar pv power plant, battery energy storage system, wind power, solar photovoltaic power, correlation coefficient, spot market prices and RES negative correlation, bidding model methodology, real time model methodology, forecast error minimization, reducing curtailment, reducing penalties

BACKGROUND

Penetration rates of RES expanded during the last years due to increased environmental conscience and market acceptance. Another benefit of combining wind and solar photovoltaic power from the system operator’s point of view is a better utilization of grid infrastructure and reduced congestion: improving security of energy supply and system stability. Enhanced Features of Wind-Based Hybrid Power Plants – Kaushik Das et. al.

The main challenge with RES is their inherent variability due to the stochastic nature of the RES causing some difficulties as severe power ramps, up and down, and increased volatility in the power generation in general. In future WPPs and PVPPs need to participate more in the energy markets. Adding energy storage we will increase the dispatchability of RES. Wind and solar photovoltaic power don’t reliably produce power on demand, so including energy storage system is a mitigation strategy.

Negative impact associated to stochastic nature of RES can be reduced by coupling WPPs and PVPPs with BESS. Energy storage will be more relevant even where power prizes are correlated negatively with renewable power production.

Battery storage is one of several technology options that can enhance power system flexibility and enable high levels of renewable energy integration. Studies and real-world experience have demonstrated that interconnected power systems can safely and reliably integrate high levels of renewable energy from VRE sources without new energy storage resources. Grid-Scale Battery Storage Frequently Asked Questions – Thomas Bowen, Ilya Chernyakhovskiy, Paul Denholm

Energy storage allows RES to increase their revenue providing flexibility and time shifting of the power production. We have to take into account that increasing the integration of RES also increases energy curtailment situations due to power overproduction compared to grid connection constrain.

In order to participate in energy market, variable renewable energy sources need to reduce the uncertainty of forecast errors. Inclusion of storage can be a viable option not only to minimize the penalties due to forecast uncertainties but also to maximize the revenue generation Optimal operation of battery for wind-storage hybrid power plant – Kaushik Das et. al.

Wind and solar photovoltaic power are used in convex optimisation algorithm for making day ahead decisions on battery operation. One day ahead optimized results are used as input for the operating model.

Adding BESS in the WPP and PVPP we have several advantages as:

• minimize the penalties due to forecast uncertainties.
• minimize the excess energy spilt.
• maximize the revenue generation.

Including BESS we will reduce the impact of the forecast error associated to wind and solar photovoltaic power production forecasts so it’ll reduce balancing penalty too.