Optimal Power Flow for economic load dispatch

Power System Planning for Renewable Energy Integration in to
Power System
Electrical Engineering Department
Motilal Nehru National Institute of Technology Allahabad
Prayagraj, UP, India
Economic Operation of Power System Lab
(EE-22121)

Introduction
 Renewable energy sources (RES) such as solar photovoltaics (PV) and
wind energy are increasingly integrated into modern power systems to
reduce carbon emissions and enhance energy sustainability.
 However, their intermittent and stochastic nature poses significant
challenges to power system stability, reliability, and efficiency.
 This detailed analysis explores the Environmental, technical, economic,
and operational impacts of renewable integration on power systems.
S.No Sector Installed Capacity
1 Solar 102.56GW
2 Wind 48.58GW
3 Hydro 5100 MW
4 Large Hydro 46.96 GW
5 Bio-power 11.4 GW

Environmental Effects
 Shifting from coal/gas to renewables reduces greenhouse gases (GHG).
CO Emission Reduction
₂
 End-of-life disposal of solar panels and lithium batteries must be managed.
Land Use Concerns
 Large solar and wind farms require space, affecting ecosystems.
Waste from Solar Panels & Batteries

Technical Impacts of Renewable Energy Integration
 Power quality refers to maintaining voltage, frequency, and waveform stability within
acceptable limits. High penetration of RES can cause the following:
 Voltage Fluctuations
 Harmonics and Waveform Distortion
 Frequency Instability
Power Quality Issues
Grid Stability Challenges
 Power system stability is categorized into:
 Frequency Stability
 Voltage Stability
 Transient Stability

Operational Challenges of Renewable Energy Integration
 Solar PV and wind energy depend on weather conditions, leading to uncertainty in power
generation.
 Forecasting techniques, such as machine learning and statistical models, improve generation
predictability.
Intermittency and Variability
Reserve Requirements
 Grid operators must maintain backup power (spinning and non-spinning reserves) to
compensate for renewable energy fluctuations.
 Battery Energy Storage Systems (BESS) and pumped hydro storage help mitigate
intermittency.
Congestion in Transmission & Distribution Networks
 Renewable power plants are usually located far from demand centers.
 Large-scale renewable integration requires grid expansion and reinforcement to prevent
congestion.

Economic and Market Impacts of Renewable Integration
 High penetration of RES reduces electricity prices during peak generation periods (e.g.,
mid-day solar peaks).
 Negative pricing can occur when supply exceeds demand, requiring demand-side
management (DSM).
Electricity Market Price
Volatility
 Thermal power plants (coal, gas) experience reduced running hours, affecting their
economic viability.
 Flexible generation technologies such as gas turbines and hydropower are necessary to
balance renewables.
Reduced Utilization of Conventional Power Plants
Incentives and Policy Regulations
 Governments provide incentives like feed-in tariffs (FiTs), renewable portfolio standards
(RPS), and carbon credits to promote RES integration.

Solutions to Mitigate Renewable Energy Integration Challenges
 Battery storage (Li-ion, flow batteries) stabilizes grid frequency and voltage.
 Pumped hydro storage (PHS) and compressed air energy storage (CAES) support long-
duration storage.
Energy Storage Systems (ESS)
 Demand-side management adjusts consumer demand based on grid conditions.
 Smart grids use real-time data to optimize power generation and consumption.
Demand Response (DR) and Smart Grid Technologies
 Combining solar, wind, and storage ensures a more reliable power supply.
 Hybrid microgrids can operate in both grid-connected and islanded modes.
Hybrid Renewable Energy Systems (HRES)

Solutions to Mitigate Renewable Energy Integration Challenges
 Smart Grids & IoT-based Monitoring
 Energy Storage (Batteries, Pumped Hydro, Hydrogen Storage).
 Demand Response Programs.
 Flexible Generation from Gas/Hybrid Plants.
 Advanced Power Electronics (Smart Inverters, FACTS, HVDC)
Solutions for Effective Renewable Integration

Mathematical Formulation
Solar Power Generation
 
 
1000
panel solar
solar
Irradiance t A
P t

 

Where,
 
solar
P t - Solar power output at
time t (kW)
Irradiance(t) = Solar irradiance at time t (W/m²)
Apanel= Total panel area (m²)
ηsolar= Efficiency of solar panels
Wind Power Generation
 
 
3
wind
wind rated
rated
V t
P t P
V
 
  
 
 
wind
P t
Where,
Wind power output at time t (kW)
Prated= Rated power of wind turbine (kW)
Vwind
(t) = Wind speed at time t (m/s)
Vrated= Rated wind speed (m/s)

Demand Response (DR) Load Reduction
To reduce the peak-hour demand
     
, 1
load DR load
P t P t 
  
Where,
 
,
load DR
P t Adjusted demand after DR at time t (kW)
𝑡
 
load
P t Original demand at time t (kW)
DR reduction factor (e.g., 0.30.30.3 or 30% reduction)
α
Battery Energy Storage System (BESS)
Charging Condition:
     
 
arg max
min
battery surplus ch e
P t P t E SoC t

  
Discharging Condition:
 
 
 
max
arg
min
surplus
battery
disch e
P t
P t E SoC t

 
 
 
 
 
 
battery
P t Battery charging/discharging power (kW)

Demand Response (DR) Load Reduction
To reduce the peak-hour demand
       
,
surplus solar wind load DR
P t P t P t P t
  
State of Charge (SOC) Update
     
1 battery
SoC t SoC t P t dt
   

Peak Demand Savings Calculation
, ,
, ,
DR wihtout DR with DR
BESS wihtout DR with BESS
Savings C C
Savings C C
 
 
, , , ,
_ peak without DR peak with DR
Peak Savings P P
 

Cost Calculation with respect DR and BESS
Total Cost without DR & BESS
Total Cost with DR
   
1
T
withoutDR load
t
C P t t


 

   
, ,
1
T
with DR load DR
t
C P t t


 

Total Cost With BESS
   
, ,
1
T
with BESS grid BESS
t
C P t t


 

Where,
λ(t) = Electricity price at time t ($/kWh)
     
, ,
grid BESS load DR battery
P t P t P t
 

Data for Model Calculation
Solar capacity = 30kW;
Efficiency Solar = 0.2;
Panel area = 100m2;
Wind capacity = 50kW;
Wind rated speed = 12 m/s
Battery capacity = 100kWh
Battery SoC= 0.5 * Battery capacity
Charging efficiency = 0.9
Discharging efficiency = 0.9
Battery initial SoC = 80%
Objective: Economic based scheduling and peak power savings with the integration of DR
and BESS into power system

Flow Chart
Start
Initialize parameters of solar, wind, BESS and Power system
Calculate the Solar and wind power generation
Apply demand response analysis(i.e., Time of Use)
If load reduced by
30% in peak hours
No
Yes
Compute load profile
Calculate net surplus power of the system
P surplus > 0
No
Yes
Charge the battery Charge the battery
Update SoC of the battery and calculate net grid demand
Calculate total cost without DR and BESS, with DR, BESS
End

Optimal Power Flow for economic load dispatch

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