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Hui Yu & Wenpeng Luan
China Electric Power Research Institute
July, 2015
Coordinated and Optimized Control of
Distributed Generation Integration
Background and introduction 1
Coordinated control of
distributed generation resource 2
Implementation examples 3
Summary 4
【Global RE Development Plan】
By 2025:
25% RE share
By 2030:
20% wind
power generation
share
USA
By 2020:
20% energy
efficiency
improvement
20% greenhouse
gas emission
reduction
20% RE share
EU
By 2050:
50% RE share
80%
greenhouse gas
emission reduction
by increasing
energy efficiency
and developing RE
Japan
By 2020:
Planned wind
power 200GW
non-fossil energy
accounts for 15% of
primary energy
consumption
CO2 emission
per unit of GDP
reduced by 40-45%
than in 2005
China
Renewable Energy will play an important role in future’s electricity supply.
3
At or near the customer site
Operation mode
Generation mainly for self use
Surplus can be sold to the grid
Solar, wind, biomass, geo-thermal, hydro, gas and
comprehensive use of multi-types energy
【New Challenges in DG Deployment and Power System Operation】
5
DG is:
Uncertain
Partially unpredictable
Unstable
Distributed integration
Independent individual
uncontrollable power source
Multiple connection points with
local grid
Group integration
Controllable load/power source
Single connection point with local
grid
From to
6
Technical solution: consider the DG and local load as a small system (i.e.
microgrid)
7
To the main grid
PCC
EV
Wind
Microgrid
Operations
PV
Storage
Heat
CHP
Markets
Service Provider
Main grid
Operations
Acted as a controllable
power resource/load from the
main grid perspective
Operate in grid integrated/
islanded mode
Technical Solution：Microgrid
8
Master-slave control of multiple DGs:
one DG acts as master
2 Coordinated control of the DGs
∼
Distribution Network
P/Q Control
V/F Control
Main ControllerSynchronous Signal Measurement for Power Network
Grid-connected
Island
DG Acts as Master
DC
AC
V,I Measurement
Power Electronic Interface
PQ Controller
DG1
Power Electronic Interface
PQ Controller
DGn……
V,I Measurement V,I Measurement V,I Measurement
Load Controller
9
Peer-to-peer control of multiple DGs
2 Coordinated control of the DGs
∼
Distribution Network
Local Load 1
AC
DC
DG1
Droop Controller1
V,I Measurement
U1
f0 V0
Local Load 2
AC
DC
DG2
U2
Power Calculation
and Decoupling
Droop Controller2
P-f&Q-V Droop
Control
Three Phase
Voltage Calculation
f
V
V,I Measurement
P Q
f0 V0
AC
DC
DGn
Droop Controller n
V,I Measurement
Un
f0 V0
Local Load n
……
Public Load
PCC
Based on hierarchical control and
energy management
• Could be 2 or 3 layers
• (3 layers structure) composed of local control,
centralized control, distribution dispatching
layer
• Comparatively mature tech.
• Maintaining the stable operation of microgrid
• Realizing the maximum utilization of REs, and
the economic objectives of microgrid
• Integrating the microgrid into the unified
dispatching of distribution network via
information exchange with distribution network
• Requiring reliable communication and
comparatively large investment
Based on multi-proxy tech.
• Composed of three proxies: component,
microgrid and distribution network level proxy
• Using the self-governing, reaction ability and
spontaneous behavior of proxy to decentralize the
complex integral control
• Reduce the complexity of centralized control
model, avoid large scale calculation and realize
real-time control
• Fast response to the change of partial grid and
reduce the workload of power quality regulation
• Current research and application mostly focus on
the coordination of market transaction and
economic of system operation, lacking deep
research on the voltage and frequency control
• Coordinated control strategy
2 Coordinated Control of the DGs
• Coordinated control strategy based on hierarchical control and
energy management
2 Coordinated Control of the DGs
微网PCC
光伏发电 微网通讯线路
电力传输线路
负荷
配电网
断路器
测控保护装置
配网调度层
集中控制层
就地控制层
风力发电 储能电池
微网能量管理系统
微网集中控制器
逆变器
电能质量治理装置
微电网并网点保护
Dispatching Layer
Distribution Network
Centralized Control Layer
MG EMS
MG Central Controller
Point of MG Connection
Local Control Layer
Inverter
Protection and Monitoring Device
Circuit Breaker
Protection at Point of MG ConnectionPower Transmission LineCommunication Line
Wind Power
PVStorage Battery
Power Quality Improving Device Load
Dispatching layer
Microgrid centralized control layer
Local control layer of Micro power source/storage/load
• Coordinated control strategy based on hierarchical control and energy
management
Pass the electric information inside microgrid to distribution network dispatching center, and
deliver the dispatching order to microgrid, making the microgrid part of the distribution dispatching by
realizing power exchange between microgrid and distribution network through connecting line.
Collect the condition data of microgrid operation
Send dispatching and switch order to local controller
Realize transformation between different communication protocols of upper and lower layer
Realize system local monitoring via IPC
Forward parameter modify order
Upload the operation condition data of micro power source, energy storage, load and equipment
of control, protection, testing and metering, to microgrid central controller
Realize control of bottom layer equipment according to orders send by microgrid central
controller
2 Coordinated Control of the DGs
• Multiple time-scale based optimal
energy management strategy
Short-term scheme
Formulate the next storage
charge/discharge and micro power
source control scheme to realize
optimal control, according to the next
day PV/wind power and load
forecast
Super short-term scheme
Modify the short-term operation
control scheme of micro power
source and load according to the
super short-term forecast and the
real-time storage SOC
Real-time dispatching
Execute the micro power source and
energy real-time dispatching strategy,
and send real time dispatching order
to relevant controller
2 Coordinated control of the DGs
短期计划
Wind/PV/Load Super Short-term Forecast
Real-time Storage SOC
Tie-line Power Constraint
Super Short-term Scheme
MG Central Controler
Send the Order
MG Energy Management
Master Station配电网调度中心Dispatching Center of Distribution Network
Modify the Scheme
Telemetry Data
Micro Power Sources/Storage/Load Controller
Send the Real-time Dispatching Order
Data CollectionMicro Power Sources and
Energy Real-time Dispatching
Wind/PV/Load Short-term Forecast
Multi-objective Optimization
Constraint
Short-term scheme
14
China microgrid projects status
3 Microgrid Projects in China
By the end of 2013, 15
microgrid projects were
constructed/under
construction
30 microgrid projects will
be completed by the end
of 2015 (planning
installed capacity of
150MW）
15
P15
① Power source: mainly wind
power and PV
② Voltage:
380V: 11 projects (71%)
10kV: 4 projects（29%）
③ Installed capacity:
11<=1MW, 4 <=5MW
④ Energy storage: 14 deployed
ESS
⑤ Operation method: integrated
operation and islanding
operation
Characteristics To the main grid
PCC
EV
Wind
Microgrid
Operations
PV
Storage
Heat
CHP
Markets
Service Provider
Main grid
Operations
3 Microgrid Projects in China
Voltage level: 380V
Capacity: PV 110kW；
Wind power 50kW; lithium
battery 42kW/50kWh
To provide power supply for
100 households farmers
and diary farm, and test
power supply in remote
rural area via microgrid
Microgrid project in east Inner Mongolia
16
3 Implementation Example
• Grid condition：35kV substation as the main power source
• Solar resource：the average possible sunshine duration is 4452.7
hours/year, sunshine duration 2916.5 hours, and shine percentage of
66%. Daytime in summer 5 am-19pm, and 8 am-17 pm in winter.
• Wind resource: the annual wind speed is 7.2m/s at 70m height, the
annual wind power density is 504.0W/m2 as level 4, and effective wind
speed hours could reach 7318h/year（3～25m/s） with steady direction.
• load demand: 100 households farmers (herdsman), with about 100kW
power consumption, and 10kW for diary farm.
P17
Site condition and demand analysis
3 Implementation Example
Microgrid project in east Inner Mongolia
18 P18
System Overview-Microgrid project in east Inner Mongolia
He'er Hongde Immigrant Village
35kV Overhead Line，53.4kM LongDong wu Zhu'er
Substation(35kV)
Box Type Substation
PV Array50kWp
Wind Driven Generator
30kW
PV Array30kWp
Lithum Battery Storage 50kWh
Wind Power Generation 20kW
PV Array30kWp
DGs
Station Power Reserve 76 Households in East Village
24 Households in West Village
Diary Farm
MGDistribution Network Electric Optical Fiber to the Home(OPLC)
3 Implementation Example
19
Conduct global
dispatching of
microgrids in the area,
ensuring the safe and
stable operation of
distribution network
Responsible for
the coordinated
control and optimal
operation of local
microgrid
Realizing the local
control and protection
of DER, ESS and
load
Coordinated control and optimal operation
Hierarchical & Coordinated Control -Microgrid project in east
Inner Mongolia
Distribution Network Dispatching CenterDistribution Network
Dispatching Layer
Energy Management Master StationMicrogrid Central
Control Layer
Energy Storage Controller
Micro-power Controller
Micro-power Controller
Load Controller
Load Controller
Energy Storage
Micro-power
Micro-power
Load Load
Micro-power/Energy Storage/Load Local
Control Layer
Microgrid Central Controller
Operation Monitoring Subsystem
Energy Management Subsystem
Real-time Dispatching
Strategy of Micro-power and Energy Storage
Modbus TCPRS485
IEC 104Ethernet
Protection at Point of MG Connection
Line Protection
3 Implementation Example
Site Pictures
Screenshot in Dispatching Center
Screenshot in Dispatching Center
23
Transforming the multiple
connections of DERs to a single
connection of microgrid
Effectively integrate DERs with distribution
network
Realize optimized operation and control of
DERs with coordination of Distribution
Management System in dispatching center
4 Summary
Microgrid
