ac/dc microgrid control presented by: pankaj d. achlerkar … _conference/14march20/theme... ·...
TRANSCRIPT
AC/DC Microgrid Control
Presented By:
Pankaj D. Achlerkar
Supervisor:
Prof. B. K. Panigrahi
Dept. of EE, IIT Delhi
Theme-1: Overall Project Management
Theme-3: Energy Storage (Modelling, Optimizing and Management)
Theme-4: Microgrid and Active Distribution System
Theme-5: Cyber Security (Cyber Infrastructure and Security)
Theme-6: DSO Functions-Energy Management
Theme-7: DSO- Market and Regulatory Issues
Theme-8: Lab Testing and Validation
Theme-9: Field Demonstration Pilots
Theme-10: Impact Analysis and Policy Recommendations
Theme-11: Capacity Building & Workforce Development
Theme-2: Distribution System Modelling and Benchmark System Development
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Theme 4: Microgrid and Active Distribution System
Objectives
Development of enhanced primary and inner control
algorithms for converter based AC and DC microgrids
Key Issues:
Low X/R ratio
Unbalanced network and loads
Weak grid scenario
Analyze impact of control actions on performance for transient
disturbances such as faults, islanding
Key Issues:
Converter response during faults
Islanding detection methodologies
Conflicts of grid-code compliance and islanding detection
Theme-8: Lab Testing and Validation
Objectives
Development of Lab Testbed to study control and protection
challenges in AC and DC Microgrids
DC Power
Supplies
VSC-2
VSC-1
LC
filter
Power
Analyzer
Rectifying unit
for 300 V DC
Typhoon HIL
602+ for
Experimental Test Bed of Autonomous
Microgrid for Testing the performance of
the controller under unbalanced loading
condition of distribution network
DSO
Three
Phase Load
RTDS Novacor for testing
protection algorithm on DC
distribution system with mixed
renewable energy sources
OPAL-RT for implementing
local and supervisory controller
for DC microgrid
3 phase auto-transformer
DC Power
Supplies
Grid connected
VSC
VSC with each leg used
as DC-DC converter
Ferrite core
inductors
Experimental Test Bed for
Grid Integrated Distributed
Storage SystemBattery Energy Storage System
Lab Testbed at IIT Delhi
Ref.: T. Kaipia et al., ”Field test environment for LVDC distribution Implementation experiences,” CIRED
2012 Workshop: Integration of Renewables into the Distribution Grid, Lisbon, pp. 1-4, 2012
# P. D. Achlerkar, V. Nougain and B. K. Panigrahi, "Backstepping Technique based Customer-end Voltage Control Strategy of DC
Distribution Network," in IEEE Journal of Emerging and Selected Topics in Power Electronics. doi: 10.1109/JESTPE.2019.2959670
𝑥3 =−1
𝐶𝑥1 + 𝜔𝑥4 +
1
𝐶𝑥5
𝑥4 =−1
𝐶𝑥2 − 𝜔𝑥3 +
1
𝐶𝑥6
𝑥5 =−1
𝐿𝑓𝑥3 −
𝑟𝑓
𝐿𝑓𝑥5 + 𝜔𝑥6 +
1
𝐿𝑓𝑉𝑖𝑑
𝑥6 =−1
𝐿𝑓𝑥4 − 𝜔𝑥5 −
𝑟𝑓
𝐿𝑓𝑥6 +
1
𝐿𝑓𝑉𝑖𝑞
Dynamics of VSC-DG: 𝑥 ≜ 𝐼𝑜𝑑 , 𝐼𝑜𝑞 , 𝑉𝑜𝑑 , 𝑉𝑜𝑞 , 𝐼𝑖𝑑 , 𝐼𝑖𝑞𝑇
Need for Robust Backstepping:
Load current 𝑥12 can be measured, however its dynamics
𝑥12 are unknown. Thus, controller has to be robust
enough to handle load dynamics.
Backstepping Approach:
Design 𝑉𝑖𝑑𝑞 such that, 𝑥56 → 𝑥56∗,
where 𝑥56∗ are such designed that, 𝑥34 → 𝑥34
∗
𝑣𝑖𝑑 = 𝐾3𝐿𝑓𝐶𝑥1 − 𝐾3 𝑟𝑓 + 𝐾5 𝑥3 −𝐾3𝐿𝑓
𝐶+ 𝐾5 𝑥5
+ 1 − 𝜔2𝐿𝑓𝐶 + 𝐾3 𝑟𝑓 + 𝐾5 𝑥3∗
𝑣𝑖𝑞 = 𝐾3𝐿𝑓𝐶𝑥2 − 𝐾3 𝑟𝑓 + 𝐾5 𝑥4 −𝐾3𝐿𝑓
𝐶+ 𝐾5 𝑥6
+𝜔𝐾3𝐿𝑓𝑥3∗ + 𝜔𝐶 𝑟𝑓 + 𝐾5 𝑥3
∗
Key Features:
• Proposed backstepping controller implements a memoryless,
instantaneous state feedback
• Simple and intuitive design process, computationally efficient
implementation
• Enhanced transient profile and robustness towards parametric
variations, DC side voltage fluctuations, load switching etc.
• Load current sensor is not necessarily required for implementation
• Stable current and voltage controllers irrespective of type of load
(balanced/unbalanced, linear/non-linear/dynamic etc.)
Eigenvalue analysis
comparison:
(a) Conventional nested PI controller
(b) Proposed robust backstepping controller
Robustness Verification:
Different type of loads
Severe load variations
DC-link voltage variations
𝟏𝝋 Bridge Rectifier
𝐋𝐂 𝐅𝐢𝐥𝐭𝐞𝐫
Gate Driver
𝐒𝐞𝐦𝐢𝐤𝐫𝐨𝐧𝟑𝛗 𝐈𝐧𝐯𝐞𝐫𝐭𝐞𝐫
𝐑− 𝐋 𝐥𝐨𝐚𝐝
3𝝋Bridge
Rectifier
Nonlinear load
𝑣𝑜 𝑎𝑏,𝑏𝑐𝑖𝑖 𝑎,𝑏,𝑐𝑖𝑜 𝑎,𝑏,𝑐
𝐏𝐚𝐫𝐤′𝐬 𝐓𝐫𝐚𝐧𝐬𝐟𝐨𝐫𝐦𝐚𝐭𝐢𝐨𝐧
2𝜋501
𝑠𝛉
𝑣𝑜 𝑑𝑞𝑖𝑖 𝑑𝑞𝑖𝑜 𝑑𝑞
𝐀𝐧𝐚𝐥𝐨𝐠𝐭𝐨
𝐃𝐢𝐠𝐢𝐭𝐚𝐥𝐂𝐨𝐧𝐯𝐞𝐫𝐬𝐢𝐨𝐧𝐓𝐬 = 𝟐𝟎 𝛍𝐬.
𝐏𝐫𝐨𝐩𝐨𝐬𝐞𝐝Voltage/Current
𝐂𝐨𝐧𝐭𝐫𝐨𝐥𝐥𝐞𝐫
𝟐
𝐕𝐝𝐜
𝐯𝐢 𝐝,𝐪
𝐈𝐧𝐯𝐞𝐫𝐬𝐞𝐏𝐚𝐫𝐤′𝐬
𝐭𝐫𝐚𝐧𝐬𝐟𝐨𝐫𝐦
𝑷𝑾𝑴𝒇𝒔𝒘= 𝟏𝟎 𝒌𝑯𝒛
𝐓𝐲𝐩𝐡𝐨𝐨𝐧 𝐇𝐈𝐋 𝟔𝟎𝟐 + 𝐂𝐨𝐧𝐭𝐫𝐨𝐥𝐥𝐞𝐫
# P. D. Achlerkar, and B. K. Panigrahi, “A Robust Backstepping Output Voltage Controller for
Standalone Voltage Sourced Converters” (Under Review)
(a) Load current variation
(d) Nonlinear loading of DG
(b) DC link voltage variation
(c) Voltage set point variation
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Tentative Future Tasks
Study of harmonic and unbalanced loading of power electronic converter
interfaces in microgrid with conventionally used controllers, and improvement of
controllers if needed
Study of islanding phenomenon of inverter interfaced DGs with practical loads
Development of better primary control strategies for power sharing in microgrids
Addition of following to the laboratory setup of AC and DC microgrids:
Photovoltaic simulator
Electronically controlled AC and DC dynamic loads
Grid simulator to study weak grid scenarios, grid contingencies and faults