Add input for ElectricStorage SOC timeseries

CHANGELOG.md

@@ -25,6 +25,11 @@ Classify the change according to the following categories:
     ### Deprecated
     ### Removed
 
+## fixed-bess-soc
+### Added
+- Add **ElectricStorage** input field `fixed_soc_series_fraction` to allow users to fix the SOC timeseries
+
+## test-runners
 ## Develop
 ### Added
 - Added constraints in `src/constraints/battery_degradation.jl` to allow use of segmented cycle fade coefficients in the model.

src/constraints/storage_constraints.jl

@@ -44,7 +44,7 @@ function add_general_storage_dispatch_constraints(m, p, b; _n="")
         @constraint(m,
             m[Symbol("dvStoredEnergy"*_n)][b, 0] == m[:dvStoredEnergy][b, maximum(p.time_steps)]
         )
-    else
+    elseif !hasproperty(p.s.storage.attr[b], :fixed_soc_series_fraction) || isnothing(p.s.storage.attr[b].fixed_soc_series_fraction)
         @constraint(m,
             m[Symbol("dvStoredEnergy"*_n)][b, 0] == p.s.storage.attr[b].soc_init_fraction * m[Symbol("dvStorageEnergy"*_n)][b]
         )
@@ -130,13 +130,25 @@ function add_elec_storage_dispatch_constraints(m, p, b; _n="")
         end
 	end
 
+    # Constrain average state of charge
     if p.s.storage.attr[b].minimum_avg_soc_fraction > 0
         avg_soc = sum(m[Symbol("dvStoredEnergy"*_n)][b, ts] for ts in p.time_steps) /
                    (8760. / p.hours_per_time_step)
         @constraint(m, avg_soc >= p.s.storage.attr[b].minimum_avg_soc_fraction * 
             sum(m[Symbol("dvStorageEnergy"*_n)][b])
         )
     end
+
+    # Constrain to fixed_soc_series_fraction
+    if hasproperty(p.s.storage.attr[b], :fixed_soc_series_fraction) && !isnothing(p.s.storage.attr[b].fixed_soc_series_fraction)      
+        @constraint(m, [ts in p.time_steps],
+        # Allow for a 1 pct point buffer on user-provided fixed_soc_series_fraction
+            m[Symbol("dvStoredEnergy"*_n)][b, ts] <= (0.02 + p.s.storage.attr[b].fixed_soc_series_fraction[ts]) * m[Symbol("dvStorageEnergy"*_n)][b]
+        )
+        @constraint(m, [ts in p.time_steps],
+            m[Symbol("dvStoredEnergy"*_n)][b, ts] >= (-0.02 + p.s.storage.attr[b].fixed_soc_series_fraction[ts]) * m[Symbol("dvStorageEnergy"*_n)][b]
+        )
+    end
 end
 
 function add_elec_storage_cost_constant_constraints(m, p, b; _n="")

src/core/energy_storage/electric_storage.jl

@@ -199,8 +199,10 @@ end
     degradation::Dict = Dict()
     minimum_avg_soc_fraction::Float64 = 0.0
     optimize_soc_init_fraction::Bool = false # If true, soc_init_fraction will not apply. Model will optimize initial SOC and constrain initial SOC = final SOC. 
+    fixed_soc_series_fraction::Union{Nothing, Array{<:Real,1}} = nothing # If provided, SOC (as fraction of total energy capacity) will not be optimized and will instead be fixed to the values provided here +- 0.02 (this buffer is to avoid infeasible solutions) 
     min_duration_hours::Real = 0.0 # Minimum amount of time storage can discharge at its rated power capacity
     max_duration_hours::Real = 100000.0 # Maximum amount of time storage can discharge at its rated power capacity (ratio of ElectricStorage size_kwh to size_kw)
+
 ```
 """
 Base.@kwdef struct ElectricStorageDefaults
@@ -241,6 +243,7 @@ Base.@kwdef struct ElectricStorageDefaults
     optimize_soc_init_fraction::Bool = false
     min_duration_hours::Real = 0.0
     max_duration_hours::Real = 100000.0
+    fixed_soc_series_fraction::Union{Nothing, Array{<:Real,1}} = nothing
 end
 
 
@@ -290,8 +293,10 @@ struct ElectricStorage <: AbstractElectricStorage
     optimize_soc_init_fraction::Bool
     min_duration_hours::Real
     max_duration_hours::Real
+    fixed_soc_series_fraction::Union{Nothing, Array{<:Real,1}} 
+
+    function ElectricStorage(d::Dict, f::Financial)
 
-    function ElectricStorage(d::Dict, f::Financial)  
         s = ElectricStorageDefaults(;d...)
 
         if s.inverter_replacement_year >= f.analysis_years
@@ -306,6 +311,16 @@ struct ElectricStorage <: AbstractElectricStorage
             throw(@error("ElectricStorage min_duration_hours must be less than max_duration_hours."))
         end
 
+        # Copy SOC input in case we need to change them
+        soc_min_fraction = s.soc_min_fraction
+        optimize_soc_init_fraction = s.optimize_soc_init_fraction
+        if !isnothing(s.fixed_soc_series_fraction) 
+            @warn "Fixing ElectricStorage soc_series_fraction to the provided fixed_soc_series_fraction. Other SOC inputs will be ignored."
+            soc_min_fraction = 0.0
+            optimize_soc_init_fraction = false
+            error_if_series_vals_not_0_to_1(s.fixed_soc_series_fraction, "ElectricStorage", "fixed_soc_series_fraction")
+        end
+
         macrs_schedule = [0.0]
         if s.macrs_option_years == 5 || s.macrs_option_years == 7
             macrs_schedule = s.macrs_option_years == 7 ? f.macrs_seven_year : f.macrs_five_year
@@ -392,7 +407,7 @@ struct ElectricStorage <: AbstractElectricStorage
             s.internal_efficiency_fraction,
             s.inverter_efficiency_fraction,
             s.rectifier_efficiency_fraction,
-            s.soc_min_fraction,
+            soc_min_fraction,
             s.soc_min_applies_during_outages,
             s.soc_init_fraction,
             s.can_grid_charge,
@@ -421,9 +436,10 @@ struct ElectricStorage <: AbstractElectricStorage
             s.model_degradation,
             degr,
             s.minimum_avg_soc_fraction,
-            s.optimize_soc_init_fraction,
+            optimize_soc_init_fraction,
             s.min_duration_hours,
-            s.max_duration_hours
+            s.max_duration_hours,
+            s.fixed_soc_series_fraction
         )
     end
 end

src/core/utils.jl

@@ -174,7 +174,8 @@ function dictkeys_tosymbols(d::Dict)
             #for ERP
             "pv_production_factor_series", "wind_production_factor_series",
             "battery_starting_soc_series_fraction",
-            "monthly_mmbtu", "monthly_tonhour"
+            "monthly_mmbtu", "monthly_tonhour",
+            "fixed_soc_series_fraction"
         ] && !isnothing(v)
             try
                 v = convert(Array{Real, 1}, v)

src/mpc/structs.jl

@@ -227,6 +227,10 @@ Base.@kwdef struct MPCElectricStorage < AbstractElectricStorage
     soc_init_fraction::Float64 = 0.5
     can_grid_charge::Bool = true
     grid_charge_efficiency::Float64 = 0.96 * 0.975^2
+    max_kw::Float64 = size_kw
+    max_kwh::Float64 = size_kwh
+    minimum_avg_soc_fraction::Float64 = 0.0
+    fixed_soc_series_fraction::Union{Nothing, Array{<:Real,1}} = nothing
 end
 ```
 """
@@ -242,6 +246,7 @@ Base.@kwdef struct MPCElectricStorage <: AbstractElectricStorage
     max_kw::Float64 = size_kw
     max_kwh::Float64 = size_kwh
     minimum_avg_soc_fraction::Float64 = 0.0
+    fixed_soc_series_fraction::Union{Nothing, Array{<:Real,1}} = nothing
 end
 
 

test/runtests.jl

@@ -3798,6 +3798,26 @@ else  # run HiGHS tests
             empty!(m2)
             GC.gc()
         end
+
+        @testset "Fixed ElectricStorage state of charge" begin
+            post_name = "fixed_pv_bess" 
+            post = JSON.parsefile("./scenarios/$post_name.json")
+
+            # Get optimal SOC
+            m1 = Model(optimizer_with_attributes(HiGHS.Optimizer, "output_flag" => false, "log_to_console" => false))
+            results = run_reopt(m1 , post)
+            lcc1 = results["Financial"]["lcc"]
+            soc_series = results["ElectricStorage"]["soc_series_fraction"]
+
+            # Fix soc_series to optimal from previous run
+            m1 = Model(optimizer_with_attributes(HiGHS.Optimizer, "output_flag" => false, "log_to_console" => false)) 
+            post["ElectricStorage"]["fixed_soc_series_fraction"] =  soc_series 
+            results = run_reopt(m1 , post)
+            lcc2 = results["Financial"]["lcc"]
+
+            @test lcc1 ≈ lcc2 rtol=0.001
+            @test maximum(abs.(soc_series - results["ElectricStorage"]["soc_series_fraction"])) <= 0.0200001
+        end 
 
         @testset "Existing HVAC (Boiler and Chiller) Costs for BAU" begin
             """

test/scenarios/fixed_pv_bess.json

@@ -0,0 +1,31 @@
+{
+    "Site": {
+        "longitude": -118.1164613,
+        "latitude": 34.5794343
+    },
+    "ElectricLoad": {
+        "doe_reference_name": "RetailStore", 
+        "annual_kwh": 876000.0
+    },
+    "ElectricTariff": {
+        "blended_annual_energy_rate": 0.10,
+        "blended_annual_demand_rate": 0
+    },
+    "Financial": {
+        "elec_cost_escalation_rate_fraction": 0.026, 
+        "offtaker_discount_rate_fraction": 0.081,
+        "analysis_years": 20, 
+        "offtaker_tax_rate_fraction": 0.4, 
+        "om_cost_escalation_rate_fraction": 0.025
+    },
+    "PV" : {
+        "min_kw": 100,
+        "max_kw": 100
+    },
+    "ElectricStorage" : {
+        "min_kw": 100,
+        "max_kw": 100,
+        "min_kwh": 200,
+        "max_kwh": 200
+    }
+}