allow for 0.02 buffer in soc

Author: adfarth

src/constraints/storage_constraints.jl

@@ -140,7 +140,11 @@ function add_elec_storage_dispatch_constraints(m, p, b; _n="")
 
     if (p.s.storage.attr[b] isa ElectricStorage || p.s.storage.attr[b] isa MPCElectricStorage) && !isnothing(p.s.storage.attr[b].fixed_soc_series_fraction)      
         @constraint(m, [ts in p.time_steps],
-            m[Symbol("dvStoredEnergy"*_n)][b, ts] == p.s.storage.attr[b].fixed_soc_series_fraction[ts] * m[Symbol("dvStorageEnergy"*_n)][b]
+        # Allow for a 2% 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

src/core/energy_storage/electric_storage.jl

@@ -190,7 +190,7 @@ end
     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. 
     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)
-    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 in each timestep 
+    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) 
 ```
 """
 Base.@kwdef struct ElectricStorageDefaults
@@ -306,10 +306,11 @@ struct ElectricStorage <: AbstractElectricStorage
         optimize_soc_init_fraction = s.optimize_soc_init_fraction
         soc_init_fraction = s.soc_init_fraction
         if !isnothing(s.fixed_soc_series_fraction) 
-            @warn "Fixing ElectricStorage soc_series_fraction to the provided 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
             soc_init_fraction = s.fixed_soc_series_fraction[1]
+            error_if_series_vals_not_0_to_1(s.fixed_soc_series_fraction, "ElectricStorage", "fixed_soc_series_fraction")
         end
 
         net_present_cost_per_kw = effective_cost(;