1
Background Aims and Objectives Methodology Buildings with installed solar panels and batteries can store electricity for personal consumption or trade to the national grid. To design a ‘smart controller’ that computes the optimal amount of electricity to be traded to the grid. To calculate the optimal electricity amount based on the input weather forecast and domestic power consumption within specified battery constraints and process model. To use model predictive control (an advanced control approach) to design the controller and Matlab® software to simulate the computation. Theoretical Approach There are five input parameters of an MPC controller to be specified (Figure 1). With these inputs, the MPC will predict the future value based on current value and optimize control action accordingly. For the next time step, the MPC will sample a new process state and the new output values will be calculated via the same algorithm. The iteration continues to compute an optimal solution. Results & Discussions Figure 1: Computation algorithm of Model Predictive Control Figure 3: The disturbance signal input (power generation + demand) Conclusion The MPC approach is capable of computing the optimal amount of electricity needed to be traded to the grid to achieve the specified constraints and control objectives. MPC controller with measured disturbance (Case 1) provides better performance and higher computational accuracy compared to the one without measured disturbance (Case 2). Future Work Designing an economic MPC controller which gives better optimisation in terms of economical performance. Including fluctuating electricity price as another input data to provide more accurate computation for revenue optimisation. Establishing networking among buildings with both solar cells and batteries for electricity trading. Figure 4: The battery energy level signal output (a) with measured disturbance (b) without measured disturbance. Input data: Power generated on 1-minute basis by a 12 m 2 domestic solar cells with 15% efficiency Domestic power consumption on 1-hour basis. The input data represent the disturbance parameter (Figure 3). Real data obtained from Australian Government Bureau of Meteorology. Objective function: Figure 2: Summary of the methodology used to perform the simulation (a) (b) Figure 5: The optimal solution for manipulated variable signal output (a) with measured disturbance (b) without measured disturbance. (a) (b) Case 1: The battery energy level contains no fluctuation Figure 4(a) The optimal solution is less noisy (little fluctuation) Figure 5(a) Case 2: The battery energy level contains fluctuations Figure 4(b) The optimal solution is more noisy (high fluctuation) Figure 5(b) The nett amount of electricity traded was computed from the area under the curve in Figure 5 (a) and (b). This was done to calculate the electricity cost. Case 1: AUD 9.53 Case 2: AUD 9.61 Both values are positive, indicating that revenue was generated The revenue generated in Case 2 (without measured disturbance) is greater than Case 1 (with measured disturbance). But Case 1 produce more accurate results due to less noisy signal and followed the specified constraint. Distributed Electricity Storage Optimisation: A Model Predictive Control Approach Author: Sheikh Mohammad Faisal Sh. Mohd. Nasir Supervisor: Prof. Jie Bao & Dr. Michael J. Tippett Research Theme: Fundamental and Enabling Research The Problem The constantly changing weather, electricity demand and price hinder correct decision making: how much electricity needs to be traded (i.e. buy and sell) such that demand is fulfilled and generated electricity is utilised while maximising revenue? Constraint: Battery: 0 kWh 10 kWh Amount of electricity to be traded: -5 kW (maximum buying) +5 kW (maximum selling) The MPC application in Matlab® was used to design the controller. Two cases were compared to show the need for forecasting and prediction: Case 1: MPC controller with measured disturbance Case 2: MPC controller without measured disturbance Controller tuning was employed to obtain more accurate optimal solution. 600 0 2 2 0 10 ) ( 5 min f t t y dt dMV MV J Set point Constraint Signal [1] Reference [1] Goodwin, G., Graebe, S., & Salgado, M. (2001). Control System Design. Michigan: Prentice Hall

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Page 1: Distributed Electricity Storage Optimisation: A Model ... · (with measured disturbance). But Case 1 produce more accurate results due to less noisy signal and followed the specified

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Background

Aims and Objectives

Methodology

• Buildings with installed solar panels and batteries can store electricity for personal

consumption or trade to the national grid.

• To design a ‘smart controller’ that computes the optimal amount of electricity to be traded to

the grid.

• To calculate the optimal electricity amount based on the input weather forecast and domestic

power consumption within specified battery constraints and process model.

• To use model predictive control (an advanced control approach) to design the controller and

Matlab® software to simulate the computation.

Sub-heading: Arial font, italic 30pt

Theoretical Approach

• There are five input parameters of an MPC controller to be specified (Figure 1).

• With these inputs, the MPC will predict the future value based on current value and optimize

control action accordingly.

• For the next time step, the MPC will sample a new process state and the new output values will

be calculated via the same algorithm. The iteration continues to compute an optimal solution.

Images/graphs appearing on this

template are placeholders only.

Number and position of

images/graphs can be customised.

Paragraph and character styles have

been set as indicated. Please do not

change formatting. However, size

and position of boxes can be

modified to fit text.

Results & Discussions

Figure 1: Computation algorithm of Model Predictive Control

Figure 3: The disturbance signal input

(power generation + demand)

Conclusion • The MPC approach is capable of computing the optimal amount of electricity needed to be

traded to the grid to achieve the specified constraints and control objectives.

• MPC controller with measured disturbance (Case 1) provides better performance and higher

computational accuracy compared to the one without measured disturbance (Case 2).

Future Work • Designing an economic MPC controller which gives better optimisation in terms of economical

performance.

• Including fluctuating electricity price as another input data to provide more accurate computation

for revenue optimisation.

• Establishing networking among buildings with both solar cells and batteries for electricity

trading.

Figure 4: The battery energy level signal output

(a) with measured disturbance (b) without measured disturbance.

• Input data:

Power generated on 1-minute basis by a 12 m2 domestic solar cells with 15% efficiency

Domestic power consumption on 1-hour basis.

• The input data represent the disturbance parameter (Figure 3).

• Real data obtained from Australian Government Bureau of Meteorology.

• Objective function:

• Specified parameters:

- Range of manipulated variable (-10 kW [max buying] – +20 kW [max selling])

- Battery capacity (physical constraint: 0 – 0.5 kWh)

- Nominal battery’s energy content (set point: 0.333 kWh)

• Controller tuning – to obtain more accurate optimal solution. This is done by changing:

- Prediction horizon (longer horizon increases prediction accuracy)

- Control horizon (longer horizon enhances better control action)

- Weighting coefficient of process output (battery’s energy level) and manipulated variable

(Higher coefficient produce greater control action)

Figure 2: Summary of the methodology used to perform the simulation

(a) (b)

Figure 5: The optimal solution for manipulated variable signal output

(a) with measured disturbance (b) without measured disturbance.

(a) (b)

• Case 1: The battery energy level contains no fluctuation Figure 4(a)

The optimal solution is less noisy (little fluctuation) Figure 5(a)

• Case 2: The battery energy level contains fluctuations Figure 4(b)

The optimal solution is more noisy (high fluctuation) Figure 5(b)

• The nett amount of electricity traded was computed from the area under the curve in Figure 5

(a) and (b). This was done to calculate the electricity cost.

Case 1: AUD 9.53

Case 2: AUD 9.61

Both values are positive, indicating that revenue was generated

• The revenue generated in Case 2 (without measured disturbance) is greater than Case 1

(with measured disturbance). But Case 1 produce more accurate results due to less noisy

signal and followed the specified constraint.

Distributed Electricity Storage Optimisation:

A Model Predictive Control Approach Author: Sheikh Mohammad Faisal Sh. Mohd. Nasir

Supervisor: Prof. Jie Bao & Dr. Michael J. Tippett

Research Theme: Fundamental and Enabling Research

The Problem • The constantly changing weather, electricity demand and price hinder correct decision

making: how much electricity needs to be traded (i.e. buy and sell) such that demand is

fulfilled and generated electricity is utilised while maximising revenue?

• Constraint:

Battery: 0 kWh – 10 kWh

Amount of electricity to be traded: -5 kW (maximum buying) – +5 kW (maximum selling)

• The MPC application in Matlab® was used to design the controller.

• Two cases were compared to show the need for forecasting and prediction:

Case 1: MPC controller with measured disturbance

Case 2: MPC controller without measured disturbance

• Controller tuning was employed to obtain more accurate optimal solution.

600

0

2

2

0

10)(5minft

t

ydt

dMVMVJ

Set point

Constraint

Signal

[1]

Reference [1] Goodwin, G., Graebe, S., & Salgado, M. (2001). Control System Design. Michigan: Prentice Hall