IEC TS 62898-3-3:2023

IEC TS 62898-3-3 ®
Edition 1.0 2023-08
TECHNICAL
SPECIFICATION
colour
inside
Microgrids –
Part 3-3: Technical requirements – Self-regulation of dispatchable loads

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IEC TS 62898-3-3 ®
Edition 1.0 2023-08
TECHNICAL
SPECIFICATION
colour
inside
Microgrids –
Part 3-3: Technical requirements – Self-regulation of dispatchable loads

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 29.240.01  ISBN 978-2-8322-7336-4

– 2 – IEC TS 62898-3-3:2023 © IEC 2023
CONTENTS
FOREWORD . 4
INTRODUCTION . 6
1 Scope . 7
2 Normative references . 7
3 Terms, definitions, abbreviated terms and symbols . 7
3.1 Terms and definitions . 8
3.2 Abbreviated terms and symbols . 16
3.2.1 Abbreviated terms . 16
3.2.2 Symbols . 16
4 Requirements on self-regulation . 17
4.1 General . 17
4.1.1 Operational ranges . 17
4.1.2 Continuous and discrete control . 17
4.1.3 Dead band . 18
4.1.4 Accuracy and resolution . 18
4.1.5 Step response objective . 19
4.1.6 Damping . 20
4.2 Frequency stabilization . 20
4.2.1 General . 20
4.2.2 Continuously controllable loads . 21
4.2.3 Switchable loads. 23
4.2.4 Recommended default values . 24
4.3 Voltage stabilization . 24
4.3.1 General . 24
4.3.2 Continuously controllable loads . 25
4.3.3 Switchable loads. 26
4.3.4 Recommended default values . 27
4.4 Hybrid controls for both voltage and frequency . 28
5 Testing . 28
5.1 General . 28
5.2 Test for frequency response of self-regulated loads . 30
5.2.1 Purpose . 30
5.2.2 Procedure . 30
5.2.3 Criteria . 30
5.2.4 Comments . 30
5.3 Test for voltage response of self-regulated loads . 30
5.3.1 Purpose . 30
5.3.2 Procedure . 30
5.3.3 Criteria . 31
5.3.4 Comments . 31
Annex A (informative) Background information about the self-regulation effect . 32
Annex B (informative) Choice of coefficients k and k . 34
f U
B.1 General . 34
B.2 Expression of coefficient k for self-regulation of frequency . 34
f
B.3 Example of frequency settings in an isolated microgrid . 35
B.4 Example of frequency settings in a large interconnected network . 36

B.5 Expression of coefficient k for self-regulation of voltage. 37
U
B.6 Example of voltage settings in an isolated microgrid . 38
Annex C (informative) Prioritization of loads . 40
Annex D (informative) Damping measure in electric power systems . 44
Annex E (informative) Formula development on the relation of power and torque . 46
Annex F (informative) Examples for desynchronisation strategies . 47
F.1 General . 47
F.2 Heterogeneous load types . 47
F.3 Fuzzy or randomized control logic . 47
F.4 Emulating continuously controllable loads . 47
Bibliography . 48

Figure 1 – Hysteresis curve of a switchable load . 10
Figure 2 – Typical step response of a system . 12
Figure 3 – Example of P(f) self-regulation before and after activating the dead band . 18
Figure 4 – Bode diagram of a typical differential loop . 21
Figure 5 – Time domain response of first order low-pass filter . 22
Figure 6 – Functional diagram of a combined frequency control function for
continuously controllable dispatchable loads . 22
Figure 7 – Example of a hysteresis controller to control the temperature of a freezer in
response to variations in grid frequency . 23
Figure 8 – Functional diagram of a combined voltage control function for continuously
controllable dispatchable loads . 26
Figure 9 – Schematic diagram for the test environment of a self-regulated load . 28
Figure A.1 – Frequency development after a disturbance . 32
Figure A.2 – Particle model of switchable loads . 33
Figure B.1 – Example of P(f) self-regulation in an isolated microgrid . 36
Figure B.2 – Example of P(f) self-regulation in a large interconnected network . 37
Figure B.3 – Example of P(U) self-regulation in an isolated microgrid . 39
Figure C.1 – Frequency distribution of the power frequency of a 50 Hz network . 40
Figure C.2 – Four different droop curves according to prioritization . 41
Figure C.3 – Schematic representation of voltage probability distribution . 42
Figure D.1 – Typical location for desired eigenvalues . 44

Table 1 – Declared frequency measurement accuracy levels . 18
Table 2 – Declared voltage measurement accuracy levels . 19
Table 3 – Time quality levels . 19
Table 4 – Performance quality levels . 20
Table B.1 – Relationship between k and droop for self-regulation of frequency . 35
f
Table B.2 – Relationship between k and droop for self-regulation of voltage . 38
U
Table C.1 – Frequency domain (example for 50 Hz systems) . 41
Table C.2 – Frequency domain (example for 60 Hz systems) . 41
Table C.3 – Voltage domain (example) . 43

– 4 – IEC TS 62898-3-3:2023 © IEC 2023
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
MICROGRIDS –
Part 3-3: Technical requirements –
Self-regulation of dispatchable loads

FOREWORD
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