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Effective Capacity of a Battery Energy Storage System Captive to a Wind Farm

Vinay A. Vaishampayan, Thilaharani Antony, Amirthagunaraj Yogarathnam

Abstract

Wind energy's role in the global electric grid is set to expand significantly. New York State alone anticipates offshore wind farms (WFs) contributing 9GW by 2035. Integration of energy storage emerges as crucial for this advancement. In this study, we focus on a WF paired with a captive battery energy storage system (BESS). We aim to ascertain the capacity credit for a BESS with specified energy and power ratings. Unlike prior methods rooted in reliability theory, we define a power alignment function, which leads to a straightforward definition of capacity and incremental capacity for the BESS. We develop a solution method based on a linear programming formulation. Our analysis utilizes wind data, collected by NYSERDA off Long Island's coast and load demand data from NYISO. Additionally, we present theoretical insights into BESS sizing and a key time-series property influencing BESS capacity, aiding in simulating wind and demand for estimating BESS energy requirements.

Effective Capacity of a Battery Energy Storage System Captive to a Wind Farm

Abstract

Wind energy's role in the global electric grid is set to expand significantly. New York State alone anticipates offshore wind farms (WFs) contributing 9GW by 2035. Integration of energy storage emerges as crucial for this advancement. In this study, we focus on a WF paired with a captive battery energy storage system (BESS). We aim to ascertain the capacity credit for a BESS with specified energy and power ratings. Unlike prior methods rooted in reliability theory, we define a power alignment function, which leads to a straightforward definition of capacity and incremental capacity for the BESS. We develop a solution method based on a linear programming formulation. Our analysis utilizes wind data, collected by NYSERDA off Long Island's coast and load demand data from NYISO. Additionally, we present theoretical insights into BESS sizing and a key time-series property influencing BESS capacity, aiding in simulating wind and demand for estimating BESS energy requirements.

Paper Structure

This paper contains 16 sections, 2 theorems, 32 equations, 7 figures.

Table of Contents

  1. Introduction
  2. The Power Alignment Function
  3. Computing the Effective Capacity
  4. Definitions of Energy and Power Terms
  5. Linear Program for the Power Alignment Function
  6. Greedy Charging Protocol
  7. Numerical Results based on Measured Wind Velocity
  8. Wind Power Data
  9. Power Alignment Function and Capacity Estimates
  10. Theoretical Results
  11. A General Lower Bound for $\bm{g}_{av}(B,P)$
  12. Graph Interpretation and Refinements of the Lower Bound
  13. Behavior of the Greedy Charging Protocol
  14. Endpoints of the Power Alignment Function
  15. Summary and Conclusions
  16. ...and 1 more sections

Key Result

Theorem 1

The average and peak peaker power with no battery storage ($B=0$, $P=0$) are given by

Figures (7)

  • Figure 1: Test setup for calculating the power alignment function $g(B,P)$.
  • Figure 2: Power Alignment Functions for a Day 1, $\bm{g}_{av}(B,P)$ (top), $\bm{g}_{peak}(B,P)$ (bottom). The corresponding wind power and demand traces are in Fig. \ref{['fig:threedaysdata']}.
  • Figure 3: Wind and demand traces for 9/20/2019 (Day 1), 9/03/2019 (Day 2) and 9/04/2019 (Day 3). Average demand power has been adjusted to equal average wind power.
  • Figure 4: (Top left) Normalized average capacity $(\bm{g}_{av}(0,0)-\bm{g}_{av}(B,B/4))/\bm{g}_{av}(0,0)$, (Top right) Normalized peak capacity, (Bottom left) Incremental average capacity $-d\bm{g}_{av}(B,P)/dP$ (for a 4 hour BESS i.e. $B=4P$) (Bottom right) incremental peak capacity. $5$% battery loss. Based on wind and demand traces for the 3 days shown in Fig. \ref{['fig:threedaysdata']}.
  • Figure 5: Random sequence $R$ with local extrema marked with red circles.
  • ...and 2 more figures

Theorems & Definitions (12)

  • Definition 1
  • Remark 1
  • Remark 2
  • Definition 2
  • Definition 3
  • Remark 3
  • Theorem 1
  • proof
  • Remark 4
  • Theorem 2
  • ...and 2 more