bug fixes for max net metering benefit, multi-period and multi-tier demand charges

CHANGELOG.md

@@ -26,6 +26,9 @@ Classify the change according to the following categories:
 ## Develop
 ### Fixed
 - Convert `max_electric_load_kw` to _Float64_ before passing to function `get_chp_defaults_prime_mover_size_class`
+- Increased the big-M bound on maximum net metering benefit to prevent artificially low export benefits
+- Fixed a bug in which tier limits did not load correctly when the number of tiers vary by period in the inputs
+- Set a limit for demand and energy tier maxes to avoid errors returned by HiGHS due to numerical limits
 
 ## v0.46.1
 ### Changed

src/constraints/electric_utility_constraints.jl

@@ -52,7 +52,7 @@ function add_export_constraints(m, p; _n="")
             @warn "Adding binary variable for net metering choice. Some solvers are slow with binaries."
 
             # Good to bound the benefit - we use max_bene as a lower bound because the benefit is treated as a negative cost
-            max_bene = sum([ld*rate for (ld,rate) in zip(p.s.electric_load.loads_kw, p.s.electric_tariff.export_rates[:NEM])])*10
+            max_bene = sum([ld*rate for (ld,rate) in zip(p.s.electric_load.loads_kw, p.s.electric_tariff.export_rates[:NEM])])*p.pwf_e*p.hours_per_time_step*10
             NEM_benefit = @variable(m, lower_bound = max_bene)
 
 
@@ -135,7 +135,7 @@ function add_export_constraints(m, p; _n="")
         else
             binWHL = @variable(m, binary = true)
             @warn "Adding binary variable for wholesale export choice. Some solvers are slow with binaries."
-            max_bene = sum([ld*rate for (ld,rate) in zip(p.s.electric_load.loads_kw, p.s.electric_tariff.export_rates[:WHL])])*10
+            max_bene = sum([ld*rate for (ld,rate) in zip(p.s.electric_load.loads_kw, p.s.electric_tariff.export_rates[:WHL])])*p.pwf_e*p.hours_per_time_step*100
             WHL_benefit = @variable(m, lower_bound = max_bene)
 
             @constraint(m, binNEM + binWHL == 1)  # can either NEM or WHL export, not both

src/core/urdb.jl

@@ -229,7 +229,7 @@ function parse_urdb_energy_costs(d::Dict, year::Int; time_steps_per_hour=1, bigM
         energy_tier_max = get(energy_tier, "max", bigM)
 
         if "rate" in keys(energy_tier) || "adj" in keys(energy_tier)  || "sell" in keys(energy_tier)
-            append!(energy_tier_limits_kwh, energy_tier_max)
+            append!(energy_tier_limits_kwh, min(energy_tier_max, bigM))
         end
 
         if "unit" in keys(energy_tier) && string(energy_tier["unit"]) != "kWh"
@@ -313,8 +313,8 @@ Parse monthly ("flat") and TOU demand rates
 """
 function parse_demand_rates(d::Dict, year::Int; bigM=1.0e8, time_steps_per_hour::Int)
     if haskey(d, "flatdemandstructure")
-        scrub_urdb_demand_tiers!(d["flatdemandstructure"])
         monthly_demand_tier_limits = parse_urdb_demand_tiers(d["flatdemandstructure"])
+        scrub_urdb_demand_tiers!(d["flatdemandstructure"])
         n_monthly_demand_tiers = length(monthly_demand_tier_limits)
         monthly_demand_rates = parse_urdb_monthly_demand(d, n_monthly_demand_tiers)
     else
@@ -324,8 +324,8 @@ function parse_demand_rates(d::Dict, year::Int; bigM=1.0e8, time_steps_per_hour:
     end
 
     if haskey(d, "demandratestructure")
-        scrub_urdb_demand_tiers!(d["demandratestructure"])
         tou_demand_tier_limits = parse_urdb_demand_tiers(d["demandratestructure"])
+        scrub_urdb_demand_tiers!(d["demandratestructure"])
         n_tou_demand_tiers = length(tou_demand_tier_limits)
         ratchet_time_steps, tou_demand_rates = parse_urdb_tou_demand(d, year=year, n_tiers=n_tou_demand_tiers, time_steps_per_hour=time_steps_per_hour)
     else
@@ -391,7 +391,8 @@ function parse_urdb_demand_tiers(A::Array; bigM=1.0e8)
     for period in range(1, stop=length(A))
         demand_max = Float64[]
         for tier in A[period] 
-            append!(demand_max, get(tier, "max", bigM))
+            tier_max = get(tier, "max", bigM)
+            append!(demand_max, min(bigM, tier_max))
         end
         demand_tiers[period] = demand_max
         append!(demand_maxes, demand_max[end])  # TODO should this be maximum(demand_max)?

test/runtests.jl

@@ -590,7 +590,7 @@ else  # run HiGHS tests
             d["PV"]["can_wholesale"] = true
             m = Model(optimizer_with_attributes(HiGHS.Optimizer, "output_flag" => false, "log_to_console" => false))
             results = run_reopt(m, d)
-            @test results["PV"]["size_kw"] ≈ 84.029 atol=1e-3  #max benefit provides the upper bound
+            @test results["PV"]["size_kw"] ≈ 7440.0 atol=1e-3  #max benefit provides the upper bound
 
         end
     end
@@ -1186,6 +1186,16 @@ else  # run HiGHS tests
                 @test results["PV"]["size_kw"] ≈ p.s.pvs[1].existing_kw
             end
 
+            @testset "Multi-tier demand rates" begin
+                #This test ensures that when multiple demand regimes are included that the tier limits load appropriately
+                d = JSON.parsefile("./scenarios/no_techs.json")
+                d["ElectricTariff"] = Dict()
+                d["ElectricTariff"]["urdb_response"] = JSON.parsefile("./scenarios/multi_tier_urdb_response.json")
+                s = Scenario(d)
+                p = REoptInputs(s)
+                @test p.s.electric_tariff.tou_demand_tier_limits[1] ≈ 100.0 atol=1.0e-4
+            end
+
             @testset "Tiered TOU Demand" begin
                 data = JSON.parsefile("./scenarios/tiered_tou_demand.json")
                 model = Model(optimizer_with_attributes(HiGHS.Optimizer, "output_flag" => false, "log_to_console" => false))