Addition of dispatchable loads in MATPOWER

How do you add dispatchable loads such as battery stoarge and wind into MATPOWER?

Answer 1

[Ayush]

Hi Raymond,

I understand you need to add dispatchable loads such as battery storage and wind, into MATPOWER. It usually involves representing these resources as a combination of generators, loads, and possibly storage devices.

You can model these systems by integrating appropriate data into MATPOWER’s format.

1. Battery Storage

It is typically modeled as a generator with a certain energy limit, where the energy input/output can be controlled based on the charging or discharging cycle.

Steps to add battery storage (Modeling as a Generator):

1. Active Power Generation (P): The battery's power output can be treated as a negative load when discharging, and as a positive generator when charging.
2. Reactive Power Generation (Q): You can either set the reactive power to zero or model it according to the battery’s capability.
3. Energy Limits: To account for the battery's state of charge (SOC), you need to ensure the generator has energy limits, typically specified in terms of energy stored in kWh, which is a constraint during optimization.
4. Charge/Discharge Power Limits: These are the maximum and minimum power values for charging and discharging.

Here’s a pseudo code for your reference:

% Adding battery storage as a generator in the generator matrix (gencost, gen)

mpc.gen = [
    
%bus Pg Qg Qmax Qmin Vg mBase status Pmax Pmin

3, 0, 0, 30, -30, 1.0, 100,  1, 50, -50; % Battery Storage

];



% Defining battery-specific generator cost (gencost matrix)

mpc.gencost = [
    
2,   0,   0,   3,    0.1,    0,    0; % For the battery cost function (simple)

];



% Add energy limits (for example, 100 kWh of energy)

battery_energy_limit = 100; % kWh

mpc.storage = [
    
3, battery_energy_limit, 0, 50, -50;  % Energy stored, max charge/discharge

];

2. Wind Generation

Wind generation is typically modeled as a stochastic or probabilistic generator since its output is variable and depends on wind speeds, which are not controllable.

Steps to add wind generation:

1. Wind turbines can be modeled as generators with a variable output based on a time-varying or probabilistic distribution. You may either use a fixed power generation model or integrate wind speed as an input.
2. Power Limits: Wind generation usually has a maximum (Pmax) based on the installed capacity, and the output varies with wind speed, which may be represented as a probabilistic curve or modeled with some uncertainty.
3. Stochastic Models: If you want a more advanced representation, you could integrate external data or stochastic methods to model the variability of wind generation.Here’s the pseudo code for your reference:

% Adding wind generation as a generator in the generator matrix (gencost, gen)

mpc.gen = [
    
% bus  Pg   Qg   Qmax   Qmin   Vg   mBase  status  Pmax  Pmin

5,   0,   0,   100,   0,     1.0, 100,  1,   50,    0;  % Wind Generation

];



% Wind turbine cost function (simplified, flat rate)

mpc.gencost = [
    
2,   0,   0,   3,    0.05,  0,    0;  % For wind turbine cost

];

Note: In MATPOWER, there is no built-in mechanism for time-varying data or probabilistic generation directly. However, you can modify the power output of the wind and battery storage resources as part of a time-series simulation or perform dynamic simulations.

For example:

• Battery Storage: The power output can be set as a time-varying input, depending on the state of charge (SOC) and the load demand.
• Wind Power: The wind power output could be defined based on hourly or seasonally varying inputs, which you can modify manually or fetch from an external time-series dataset.

Example for your reference:

% Define the battery system (as a generator)

mpc.gen = [
    
3,   0,   0,   50,    -50,    1.0,  100,  1,   50,    -50;  % Battery on bus 3

5,   0,   0,   100,    0,     1.0,  100,  1,   50,    0;    % Wind on bus 5

];



mpc.gencost = [
    
2,   0,   0,   3,    0.1,    0,    0;   % Cost function for battery

2,   0,   0,   3,    0.05,   0,    0;   % Cost function for wind

];

Hope it helps!