The integration and control of multifunctional

THE INTEGRATION AND CONTROL OF MULTIFUNCTIONAL STATIONARY PV-BATTERY SYSTEMS IN SMART DISTRIBUTION GRID

Mohammad Rezwan Khan

Objective Usage of battery system for defer upgrades needed in case of large penetration of • electric vehicle (EV), • electrified heat pump (HP) • photovoltaic (PV) panel • Approach Techno economic optimal sizing

• Consider season-based diurnal dynamics

Intended functions  PrimaryThe counterbalance of overloading of transformer  SecondaryArbitrage (buy low, sell high)

Find the optimal storage for satisfying daily energy dynamics.

Challenges • Consideration o Geographic location of the BESS system around the globe, o Power demand profiles, o Electricity pricing policies. • BESS Have investment and operating cost. • Different Technologies  Pb-Ac battery  Li-ion battery

Sizing a BESS device too small may  reduce its operating life through over use, such as exceeding maximum depth of discharge too frequently  Long term costs in addition to finite life time or render it ineffective for the required function (in the paper peak shaving). Sizing a device too large will result  increased capital costs  bigger cost of supplying energy.

Input • A given load profile encompassing of EV, HP and household data, PV generation power profile and tariff systems • Extrapolate data into Transformer load -No power loss while transmission.

• Market Profile: Time varying dynamic market price  Low when demand is low  High when demand is high

Attributes

Cycle life Charge efficiency,𝜂𝑐 Discharge efficiency,𝜂𝑑 Nominal Energy Specific cost of the battery system,𝐶𝐸𝑏𝑎𝑡 Battery peripheral lifetime Shelf life Allowable DoD

Li ion systems 1500 90%

Pb Acid systems 500 80%

98%

98%

1000€/kWh

400€/kWh

10 year

10 year

25 year 80%

10 year 50%

Input

Load profile of Household

Probabilistic Load profile of Household

Work flow

Market Model

Cumulative load profile in a transformer

In summer No overloading In a sunny day lot of Energy but less to consume

In midseason(spring/ Fall) -Less sun -Moderate load

In winter -Not adequate sun -More loads are operating Load profile of Transformer

Find an optimal size that would provide best output ensuring lifetime.

Approach Linear Programming • The first stage sets limits the In a linear programming exercise, options for storage size  all the participating information and stemming from different corresponding constrains of a specific allowable transformer loading time period is available level.  the algorithm is able to optimise the power flow of the battery given that • The second stage optimises the price profile and load profile is for BESS operation within given beforehand. technical and economic limits considering daily dynamics.

 a single method can incorporate the technical constraints of a real system and the correlations between input data sets while producing a lowest cost solution.

Governing Equations Market Model _ BPX

𝑚𝑖 = (0.44 + 0.56𝑚𝑖

_ BPX

) ∗ 0.18

𝑚𝑘 = (0.14 + 0.86𝑚𝑘

) ∗ 0.18…City €c/kWh

London 13

Berlin 19

Antwerp 18

Battery State of Energy Model 𝛦𝑚𝑖𝑛 ⩽ 𝛦0 + Δt 1,2, … . 𝑡

𝑡

(𝑃𝑖 𝜂char + 𝜂

𝑖=1

𝑃𝑖 disch

) ⩽ 𝛦𝑚𝑎𝑥 ; ∀𝑖 ∈

Virtual Cost when overloaded

Cost Functions for optimal power 𝑡 𝑚𝑎𝑥

𝑚𝑖𝑛 Δt ∗ 𝑃𝑖

𝑛𝑜_𝑜𝑣_𝑝𝑢𝑙𝑠𝑒

{𝑃𝑖 𝐶𝑖 + 𝛼1 ∗ m𝑎x(0, 𝑃𝑖 − 𝑃𝑇ℎ ) 𝑖 =1

~

+ Γ ∗ 𝜆𝐵𝐸𝑆𝑆,𝑖 ∗ 𝑚𝑎x(0, min(𝑃 𝑖 , 𝑃))

λBESS,i =

− 𝛿ij (𝐶𝑖 + 𝐶𝑚,𝑗 )𝑃𝑖}

Cost Equations Pur Sale 𝐶Total = 𝐶inv + 𝐶op + 𝐶Grid − 𝐶Grid …

𝑅𝐹 =

1−1/(1+𝑟)𝑡𝑎 −1 𝑟

𝐶inv =

CRF ∗ 𝐶BESS ∗ 𝐸nom 𝑡𝑎

𝑗

(𝐶𝑗 +𝐶𝑚,𝑗 )∗𝑃def,𝑗

𝑗 𝐶 ∗𝑃 𝑖 𝑖 def,𝑖

∗ 𝑇𝑜𝑣 …

Results

Load Flow

Battery Packs State

Results Available Curtailed Solar Energy ↑ Battery Size↑

Average Price difference buying and Selling Energy ↑ Battery Size↑

Allowable transformer loading Level ↑ Battery Size↓

Sensitivity

Cautions and Shortcomings • There is only limited knowledge of the future’s weather and the electricity demand. • The influence of demand side management is not taken into account in this work. • Results are sensitive to the energy tariff system, battery system price and performance of local controller.

Thank You