PLEXOS 6.4 Release Notes
- Upgrade Compatibility
- Changes
- Performance
- Features
- User Interface
- New Inputs
- New Outputs
- New Hidden Parameters
1. Upgrade Compatibility
This version will automatically upgrade any previous Version 5-6 database. You may need to check the upgrade notes of earlier releases for any compatibility issues.
Databases in 6.4 format will retro-grade to 6.302 however you may need to check the following properties whose meaning or default values has changed between versions:
- Line Enforce Limits and Transformer Enforce Limits might not retro-grade correctly.
- Transmission Loss Method new option 5 is not supported in earlier versions.
2. Changes
The following are the changes to existing functionality between this version and 6.302:
2.1. Transmission Loss Method
The loss method 'Successive LP' (2) has been deprecated and the new method 'Single-pass GPF' (5) introduced. This new method is fast single-pass loss estimation method that can be significantly faster than the other methods.
2.2. Line Enforce Limits and Transformer Enforce Limits
These flags has been changed from a simple Yes/No to have three options. See the help topics for more details.
2.3. Single Year LT Plan and Perpetuity
Previously the setting LT Plan End Effects Method which controls the calculation of perpetuity in the last year of simulation would not apply itself to a one year horizon.
2.4. Formulation of Outages in Partial and Fitted Chronologies
When intervals of time are combined into blocks, which occurs when using load-duration curves or when using the Chronology = "Fitted", the unit commitment must be modified to allow either de-rating of plant or partial unit commitment. In this version the formulation has been switched from relying on de-rating to a (mostly mathematically equivalent) approach of partial unit commitment. This will produce slight differences in results in the case where no-load or start costs are modelled and in general may causes small differences in MT Schedule results that affect decomposition and the resulting ST Schedule results.
3. Performance
The following changes and/or new features specifically address performance of the simulation:
- The Xpress-MP solver is updated to Version 26.
- The CPLEX solver is updated to Version 12.6.
- The MOSEK solver is updated
- In chronological versions of MT Schedule and LT Plan the option MT Schedule.Last Block Count has been enhanced so it now works on a single-step simulations. This powerful option allows you to vary the resolution of the simulation across the horizon 'e.g.' you might have 24 periods per day at the start of the horizon and reduce to 8 over the course of the horizon.
- The new settings Generator Dispatch Period and Storage Balance Period (see below) can help speed up medium and long term simulations by reducing the frequency of decisions and constraints for those two elements.
- Multi-stage stochastic optimization: Significant performance improvements have been made here and the new hanging branches feature also reduces the problem size (see below).
4. Features
4.1. Battery Class
The Battery class models battery energy storage systems (BESS) replacing the previous method of simulating BESS as pumped storage units. Battery objects can be included as expansion candidates in LT Plan and dispatchable resources in MT Schedule and ST Schedule.
4.2. Maintenance Class
The Maintenance class enables value-based reliability (VBR) modeling whereby the timing of maintenance events is optimized with respect to all costs and constraints in the simulation.
4.3. Gas Basin Class
The Gas Basin class represents a collection of gas field objects and acts as a container for reporting and defining constraints on those objects.
4.4. Generator Dispatch Period
Some generators, especially hydro, can only make changes to dispatch levels on a hourly or daily basis rather than every simulation interval, which might be 10-minutes for example. To model this inflexibility and also improve simulation performance the dispatch period for a Generator can be controlled with the Dispatch Period setting.
4.5. Storage Balance Period
To improve performance the frequency with which storage balance constraints (and hence limits) are enforced can be set with the following properties for each of the storage-related classes:
- Storage Balance Period
- Generator Balance Period
- fuel Balance Period
- Gas Field Balance Period
- Gas Storage Balance Period
- Gas Pipeline Balance Period
4.6. Decision Variables by Period Type
Decision Variable objects can now span multiple time periods rather than being defined each simulation interval. The time period for a decision variable is set in a similar way to that of Constraint in that you set the appropriate version of the Decision Variable Objective Function Coefficient property:
- Decision Variable Objective Function Coefficient Hour
- Decision Variable Objective Function Coefficient day
- Decision Variable Objective Function Coefficient Week
- Decision Variable Objective Function Coefficient Month
- Decision Variable Objective Function Coefficient Year
4.7. Multi-area Reliability
An algorithm is now available to compute reliability statistics such as LOLP on a multi-area system i.e. taking into account transmission limits. The following settings turn on/off this algorithm and production of the relevant outputs:
- LT Plan Compute Multi-Area Reliability Indices
- PASA Compute Multi-Area Reliability Indices
4.8. Multi-band Storage Non-anticipativity
The penalty function for violating non-anticipativity constraints for hydro storage is now allowed to be multi-band function. See the topic Trajectory Non-anticipativity Volume for details.
4.9. Hanging Branches Performance Improvement
When using a multi-stage scenario tree with hanging branches the number of simulation periods in the hanging branches is automatically reduced to save computational effort. See the topic Global Tree Stages Hanging Branches.
4.10. Integer Rounding Scheme for Hydro Head Effects
Setting the Hidden Parameter Production HeadEffectsOptimality = 2 invokes a two-pass integerization scheme that significantly improves performance for hydro models with head effects.
5. User Interface
No significant changes.
6. New Inputs
New inputs are:
| Collection | Property | Relates To |
|---|---|---|
| Battery | Latitude | Latitude |
| Battery | Longitude | Longitude |
| Gas Storage | Latitude | Latitude |
| Gas Storage | Longitude | Longitude |
| LT Plan | Compute Multi-area Reliability Indices | Master switch for computation of reliability indices LOLP, LOLE, etc across multiple areas |
| PASA | Compute Multi-area Reliability Indices | Master switch from computation of reliability indices LOLP, LOLE, etc across multiple areas |
| Diagnostic | Marginal Unit Transmission Detail | Transmission area for marginal unit diagnostic |
| Generator | Balance Period | Frequency of storage balance |
| Fuel | Balance Period | Frequency of storage balance |
| Fuel | Price Incr | Increment to the price of the fuel |
| Fuel | Price Scalar | Multiplier on the price of the fuel |
| Storage | Trajectory Non-anticipativity Volume | Volume of violation of non-anticipativity constraints in band |
| Storage | Balance Period | Frequency of storage balance |
| Battery | Random Number Seed | Random number seed assigned to the battery for the generation of outages |
| Battery | Repair Time Distribution | Distribution used to generate repair times (Auto,Constant,Uniform,Triangular,Exponential,Weibull,Lognormal,SEV,LEV) |
| Battery | Balance Period | Frequency of storage balance |
| Battery | Capacity | Capacity of the BESS |
| Battery | Max Power | Maximum generating capacity of each unit |
| Battery | Max SoC | Allowable maximum state of charge |
| Battery | Min SoC | Allowable minimum state of charge |
| Battery | Initial SoC | Initial state of charge |
| Battery | Charge Efficiency | Efficiency of charging |
| Battery | Discharge Efficiency | Efficiency of discharge |
| Battery | VO&M Charge | Variable operation and maintenance charge |
| Battery | UoS Charge | Us of system charge for generation |
| Battery | Max Ramp Up | Maximum ramp up rate |
| Battery | Max Ramp Up Penalty | Penalty for violating [Max Ramp Up] Constraint |
| Battery | Max Ramp Down | Maximum ramp down rate |
| Battery | Max Ramp Down Penalty | Penalty for violating [Max Ramp Down] constraint |
| Battery | Units | Number of BESS units installed |
| Battery | FO&M Charge | Fixed operations and maintenance charge |
| Battery | Maintenance Rate | Maintenance Rate |
| Battery | Maintenance Frequency | Frequency of maintenance outages in an annual time frame |
| Battery | Forced Outage Rate | Forced Outage Rate |
| Battery | Mean Time To Repair | Mean time to repair |
| Battery | Min Time to Repair | Minimum time to repair |
| Battery | Max Time To Repair | Maximum time to repair |
| Battery | Repair Time Shape | Repair time function shape parameter (for Weibull,lognormal) |
| Battery | Repair Time Scale | Repair time function scale parameter (for exponential,Weibull,lognormal,SEV,LEV) |
| Battery | Max Units Built | Maximum number of BESS units that can be built |
| Battery | Project Start Date | First date at which a BESS unit can be built |
| Battery | Technical Life | Technical lifetime of a BESS unit |
| Battery | Build Cost | Cost of building a BESS unit |
| Battery | WACC | Weighted average cost of capital |
| Battery | Economic Life | Economic life of a BESS unit (period over which fixed costs are recovered) |
| Battery | Min Units Built | Minimum number of units automatically constructed in aggregate over the planning horizon |
| Battery | Max Units Built in Year | Maximum number of BESS units that can be built in a year |
| Battery | Max Units Retired | Maximum number of units allowed to be retired in aggregate over the planning horizon |
| Battery | Max Units Retired in Year | Maximum number of units allowed to be retired in any single year of the planning horizon |
| Battery | Max Units Retired in Year | Maximum number of units allowed to be retired in any single year of the planning horizon |
| Battery | Min Units Retired in Year | Minimum number of units allowed to be retired in any single year of the planning horizon |
| Battery | x | Value to pass-through to solution |
| Battery | y | Value to pass-through to solution |
| Battery | z | Value to pass-through to solution |
| Maintenance | Duration | Duration of the maintenance event |
| Maintenance | Window | Window of time over which the maintenance is allowed |
| Maintenance | Start Window | Flag if the maintenance event is allowed to start the in the period. |
| Maintenance | End Window | Flag if the maintenance event is allowed to end the in the period |
| Maintenance | Cost | Cost of the maintenance event |
| Maintenance | Crew | Maintenance event equipment requirements |
| Maintenance | Equipment | Maintenance event equipment requirements |
| Maintenance | Lead Time | Number of hours lead time between the start of this event and the end of any prerequisites |
| Maintenance | Mutually Exclusive | If this maintenance event must occur independently of others |
| Maintenance | Penalty Cost | Cost of not scheduling this maintenance event |
| Maintenance | Min Occurrence | Number of times this event must occurs in the horizon |
| Maintenance | Min Occurrence Hour | Number of times this event must occur each hour |
| Maintenance | Min Occurrence Day | Number of times this event must occur each day |
| Maintenance | Min Occurrence Week | Number of times this event must occur each week |
| Maintenance | Min Occurrence Month | Number of times this event must occur each month |
| Maintenance | Min Occurrence Year | Number of times this event must occur each year |
| Maintenance | Non-anticipativity | Price for violating non-anticipativity constraints in scenario-wise decomposition mode |
| Maintenance | x | Value to pass-through to solution |
| Maintenance | y | Value to pass-through to solution |
| Maintenance | z | Value to pass-through |
| Gas Field | Balance Period | Frequency of storage balance |
| Gas Field | Production Volume | Volume of gas in production cost band |
| Gas Storage | Balance Period | Frequency of storage balance |
| Gas Storage | Withdrawal Rate Scalar | Maximum amount of gas that can be withdrawn from the storage |
| Gas Storage | Withdrawal Volume | Storage volume for which withdrawal is allowed |
| Gas Storage | Injection Rate Scalar | Maximum amount of gas that can be injected into the storages |
| Gas Node | Injection Volume | Storage volume for which injection is allowed |
| Gas Node | Max Production | Maximum production of gas |
| Gas Node | Min Production | Minimum production of gas |
| Gas Node | Procession Rate | Procession ratio to convert unsaleable fuel to saleable fuel |
| Gas Node | Processing Charge | Incremental cost of processing gas at the node |
| Gas Node | Consumption | The amount of saleable gas required for processing |
| Gas Pipeline | Balance Period | Frequency of storage balance |
| Region | Capacity Price Cap | Cap on the capacity price |
| Region | Capacity Price Floor | Floor on the capacity price |
| Zone | Capacity Price Cap | Cap on the capacity price |
| Zone | Capacity Price Floor | Floor on the capacity price |
| Hub | Units | Flag if hub is in service |
| Transmission Right | Units | Flag if transmission right is in service |
| Decision Variable | Objective Function Coefficient Hour | Objective function value of the generic decision variable in each hour |
| Decision Variable | Objective Function Coefficient Day | Objective function value of the generic decision variable in each day |
| Decision Variable | Objective Function Coefficient Week | Objective function value of the generic decision variable in each week |
| Decision Variable | Objective Function Coefficient Month | Objective function value of the generic decision variable in each month |
| Decision Variable | Objective Function Coefficient Year | Objective function value of the generic decision variable in each year |
| Variable | State Limits Method | Method for dealing with state limits |
| Emission Gas Nodes | Production Rate | Emissions produced per unit of fuel processed |
| Reserve Generators | Min Replacement Provision | Minimum replacement reserve provision when units are off-line |
| Reserve Generators | Replacement Offer Quantity | Replacement reserve offer quantity in offer band |
| Reserve Generators | Replacement Offer Price | Replacement reserve offer price in offer band |
| Reserve Batteries | Offer Quantity | Reserve offer quantity in offer band |
| Reserve Batteries | Offer Price | Reserve offer price in offer band |
| Maintenance Generators | Outage Rating | Unit [Rating] during outage |
| Maintenance Generators | Outage Rating Factor | Proportion of [Rating] during outage |
| Maintenance Generators | Outage Firm Capacity | Unit [Firm Capacity] during outage |
| Maintenance Generators | Outage Firm Capacity Factor | Proportion of [Firm Capacity] during outage |
| Maintenance Gas Pipelines | Outage Max Flow | Pipeline Max Flow during the outage |
| Gas Pipelines | Outage Max Flow Back | Pipeline Max Flow Back during the outage |
| Maintenance Lines | Outage Max Rating | Line rating in the reference direction during outage |
| Maintenance Lines | Outage Min Rating | Line rating in the counter-reference direction during outage |
| Regions | Max Flow | Maximum flow allowed between the regions |
| Zones | Max Flow | Maximum flow allowed between the zones |
| Constraint Generators | Firm Capacity Coefficient | Coefficient of capacity as measured by [Firm Capacity] |
| Markets | Revenue Coefficient | Coefficient of market sales revenue |
| Markets | Cost Coefficient | Coefficient of market purchase costs |
| Constraint Batteries | Generation Coefficient | Coefficient of generation |
| Constraint Batteries | Load Coefficient | Coefficient of load obligation |
| Constraint Batteries | Units Built Coefficient | Coefficient of number of units built |
| Constraint Batteries | Units Retired Coefficient | Coefficient of number of units retired |
| Constraint Batteries | Units Built in Year Coefficient | Coefficient of number of units built in the year |
| Constraint Batteries | Units Retired in Year Coefficient | Coefficient of number of units retired in the year |
| Constraint Batteries | Capacity Built Coefficient | Coefficient of capacity Built |
| Constraint Batteries | Capacity Retired Coefficient | Coefficient of capacity retired |
| Constraint Batteries | Capacity Reserves Coefficient | Coefficient of generator contribution to capacity reserves |
| Constraint Batteries | Build Cost Coefficient | Coefficient of total build cost |
| Constraint Batteries | Built Coefficient | Coefficient on binary variable indicating if any generation capacity is built to date |
| Constraint Batteries | Built in Year Coefficient | Coefficient on binary variable indicating if any generation capacity is built in the year |
| Constraint Maintenances | Hours Activate Coefficient | Coefficient of number of hours the maintenance is active |
| Constraint Maintenances | Cost Coefficient | Coefficient of maintenance cost incurred |
| Constraint Maintenances | Crew Coefficient | Coefficient of maintenance event crew usage |
| Constraint Maintenances | Equipment Coefficient | Coefficient of gas node production |
| Constraint Gas Nodes | Production Coefficient | Coefficient of gas node production |
| Regions | Firm Capacity Coefficient | Coefficient of total generator [Firm Capacity] |
| Zones | Firm Capacity Coefficient | Coefficient of total generator [Firm Capacity |
| Condition Generators | Units Sync Cond Coefficient | Coefficient of number of units running in synchronous condenser mode |
7. New Outputs
New outputs are:
| Collection | Property | Relates To |
|---|---|---|
| Emission Gas Nodes | Production | Net Production of the emission |
| Emission Gas Nodes | Cost | Emission Cost |
| Reserve Batteries | Available Response | Available Reserve Response |
| Reserve Batteries | Provision | Reserve provision |
| Reserve Batteries | Cleared Offer Price | Price of marginal offer band |
| Reserve Batteries | Cleared Offer Cost | Cost of cleared offer bands |
| Reserve Batteries | Capacity | Capacity of the BESS |
| Battery | SoC | State of Charge |
| Battery | Available SoC | State of Charge |
| Battery | Generation | generation (battery discharge) |
| Battery | Load | load (Battery recharge) |
| Battery | Net Generation | Net of generation and load |
| Battery | Losses | Total recharge and discharge losses |
| Battery | Hours Charging | Number of hours in charging state |
| Battery | Hours Discharging | Number of hours in discharging state |
| Battery | Hours Idle | Number of hours on idle state |
| Battery | VO&M Cost | Total variable operation and maintenance cost |
| Battery | UoS Cost | Total use of system cost |
| Battery | Capacity Factor | Proportion of battery discharge capacity utilized |
| Battery | Load Factor | Proportion of battery recharge load utilized |
| Battery | Price Received | Price received for generation |
| Battery | Price Paid | Price paid by load |
| Battery | Generation Revenue | Generation revenue |
| Battery | Cost to Load | Net Generation Revenue |
| Battery | Net Generation Revenue | Net of generation revenue and cost to load |
| Battery | Net Profit | Net profit |
| battery | Units | Number of installed BESS units |
| Battery | Installed Capacity | Total Capacity |
| Battery | FO&M Cost | Fixed operation and maintenance cost |
| Battery | Age | Number of cycles completed |
| Battery | Units Built | Number of BESS units built in this year |
| Battery | Build Cost | Cost of BESS unit new builds |
| Battery | Units Retired | Number of BESS units retired in this year |
| Battery | Retirement Cost | Cost of BESS unit retirements |
| Battery | x | Pass-through value (summed in summary) |
| Battery | y | Pass-through value (summed in summary) |
| Battery | z | Pass-through value (averaged in summary) |
| Maintenance | Start Date | Start date of next maintenance event |
| Maintenance | Hours Active | Number of hours the maintenance is active |
| Maintenance | Duration | Number of hours the current maintenance event has been active |
| Maintenance | Cost | Cost of the maintenance event |
| Maintenance | Crew | Maintenance event crew requirements |
| Maintenance | Equipment | Maintenance event equipment requirements |
| Maintenance | Outage | Total outage |
| Maintenance | Penalty Cost | Cost of not scheduling the maintenance event |
| Maintenance | x | Pass-through value (summed in summary) |
| Maintenance | y | Pass-through value (summed in summary) |
| Maintenance | z | Pass-through value (averaged in summary) |
| Gas Node | Raw Gas Production | The amount of raw gas processed |
| Gas Node | Sealable Gas Production | The amount of raw gas processed |
| Gas Node | Total Cost | The total cost for processing the gas |
| Gas Node | Total Consumption | The total amount of gas consumed for processing activities |
| Gas Demand | Bid Quantity | Quantity bid in band |
| Gas Demand | Bid Price | Value of gas in band |
| Gas Demand | Bid Cleared | Bid cleared in band |
| Gas Demand | Cleared Bid Price | Price of marginal bid band |
| Gas Demand | Cleared Bid Value | Area cleared under demand curve |
| Region | Multi-area LOLE | Loss of load probability |
| Region | Multi-area LOLP | Number of days of outage |
| Zone | Multi-area LOLE | Loss of load probability |
| Zone | Multi-area LOLP | Number of days of outage |
| Hub | Marginal Loss Charge | Marginal loss component of the hub price |
| Hub | Energy Charge | Energy component of the hub price |
| Hub | Congestion Charge | Congestion component of the hub price |
8. New Hidden Parameters
The following are new hidden parameters in this version. See hidden parameters for a list of all hidden parameters in this version.
| Class | ParameterName | Type | Default | Validation | Description |
|---|---|---|---|---|---|
| Production | HeadEffectsOptimality | Integer | 2 | In(1,2) | Integerization method for hydro head effects. |
| Production | HeadEffectsOptimalityRollingWindow | Integer | -1 | - | Number of intervals in the rolling horizon integerization window (-1 means whole step). |
| Stochastic | Risk Level | Double | 0.1 | Between 0 And 1 | Risk level for risk-constrained optimization where 0.1 means above 90%. |
| Stochastic | GlobalFCFName | String | "FCF" | - | Name of the FCF object when writing the FCF diagnostic file. |
| Stochastic | GlobalFCFObj | Double() | Nothing | - | Array containing the FCF objective value. |
| Reserve | SetProvisionPrice | Boolean | False | - | If the objective function should include a small penalty on Reserve provision to avoid over-providing the service. |