Simulation of Power Projects How Simulation Helps to Streamline Power Generation Processes

Author / Editor: Graham Dudgeon, PhD / Dominik Stephan

Understanding the uncertainty associated with operating variable generation systems helps manage the level of risk associated with delivering services. Moreover, appropriate selection of the rating and charge/discharge characteristics of an energy storage device, coupled with appropriate operational management, can improve the ability of a variable generation system to participate in certain markets.

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Figures 1-4
Figures 1-4
(Picture: Mathworks)

Simulation and optimization techniques can be used to investigate the characteristics that a variable generation system with energy storage should have for given operational profiles. Two examples are detailed herein. In the first, optimization techniques are used to determine the rating and charge/discharge characteristics of a variable generation system to maximize revenue on the spot market. A study of this type is based on historical data of power output and market price, and does not require detailed consideration of technology selection.

In the second example, simulations are used to explore controlling the operational characteristics of a system that combines variable generation with energy storage, and to evaluate the effect that different energy storage interface configurations will have on grid response. Initially, a high level representation of the energy storage device is used in this type of study. As the study progresses, more detailed representations of different technologies are included in the simulation framework.

Using Optimization to Manage Risk

Historical data of power output and market prices may be used to determine whether an energy storage device would improve the ability of a variable energy producer to participate in certain markets. In this article, spot market participation is considered, although the techniques discussed are applicable to ancillary markets.

Consider the energy flow in the optimization framework (refer Figure 1). Energy from the variable energy source is distributed between the grid and the energy storage device. The energy storage device may be charged from both the variable energy source and the grid.

Determining the Energy Mix – With Simulation

The optimization problem is then to determine not only the charge/discharge profile of the energy storage device over a period of time, but also to determine the most appropriate energy mix at any given time for charging the energy storage device and supplying energy to the grid. The optimization aims to maximize revenue while ensuring that physical constraints associated with operating the energy storage device are not violated.

In line with expectations, these results from an optimization for a two day period, show that that the energy storage device is charged during periods of lower market price and discharged during periods of higher market price (refer Figure 2). Note that compared to a real-world scenario, this example is relatively simplistic for illustrative purposes. In this example, storage capacity was limited to 1200 kWhr and the charge/discharge rate was limited to 200 kW.