Control Strategies for Microgrids

Ali Mehrizi-SaniAssistant Professor

School of Electrical Engineering and Computer ScienceWashington State University

Wuhan UniversityThursday, November 28, 2013

(Beautiful) Wuhan, China

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Outline

Current and Envisioned Status of the Power System– Overview of control requirements

Proposed Control Strategy– Online set point modulation

Results of Evaluation of the Strategy– Offline simulation– Real-time implementation – Fine tuning the parameters of the strategy

Applications

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Proposed Solution

Improving the response by temporarily manipulating the set point

Secondary Controller

Primary Controller

Unitxsetpoint x(t)Secondary

Controller Set Point Modulation

Primary Controller

Unitxsetpoint x(t)

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Set Point Modulation

Best Strategy– Choose T1 so that the peak of the response equals the reference– Choose T2 to be the time of this peak

Not Implementable– Faster-than-real-time simulator– Closed-form solution – System parameters

T1 tp t

x(t)

0 T1 T2tp

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Case Study I: Set Point Change

System ResponseDG2 step change from 0.91 pu to 1.09 pu

DG1 and DG3 unchanged(40% overshoot)

IEEE 34-Bus SystemAdded 3 DG units and a load

Operates in grid-connected mode

800 816

≈

824

828 830 854 852

832

858

888 890

834 860 836 840

842

844

846

848

DG3

DG2

DG1

0 1 2 3 4 5

0.9

1

1.1

(a)

I (p

u)

0 1 2 3 4 5

0.9

1

1.1

(b)I (p

u)

Time (ms)

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Case Study III: Load Disconnection

System ResponseResistive 0.5 pu load change

(15% overshoot)

800 816

≈

824

828 830 854 852

832

858

888 890

834 860 836 840

842

844

846

848

DG3

DG2

DG1

0 1 2 3 4 5 6 7 8 9 10

0.9

1

1.1

I (p

u)

Time (ms)

with SPAACE

IEEE 34-Bus SystemAdded 3 DG units and a load

Operates in grid-connected mode

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Thank You

Control Strategies for Microgrids

Ali Mehrizi-Sani

mehrizi@eecs.wsu.eduhttp://eecs.wsu.edu/~mehrizi