Smart Grid Exam 3

Disciplines of Smart Grid

Intelligent Measurements
Intelligent Decision and Control Systems
Environment - Renewables & EVs
Intelligent Power Electronics
Computational Intelligence
Cyber Security
Visual & Data Analytics
Intelligent Communications

What does AGC do

Adjusts real power outputs to maintain system frequency and scheduled tie-line power flows across interconnected areas

What is AGC

Automatic Generation Control

What does AGC correct in real-time

The Area Control Error (ACE)

What are the roles of the control layers

Primary: local governor droop -> stabilizes frequency immediately
Secondary: AGC -> restores frequency to nominal and balances tie-lines
Tertiary: Economic dispatch/OPF -> slower

Equation for Wind turbine generation

Pm = 0.5 Cp(λ

What is Pm in the Wind turbine equation

Mechanical power output of the turbine in Watts

What is Type A wind turbine?

Constant Speed Wind Turbine (WT)

What is Type B wind turbine?

Variable Speed Wind Turbine (WT)

What is Type C wind turbine?

Variable Speed Wind Turbine with partial-scale frequency converter

What is Type D wind turbine?

Variable Speed Wind Turbine with full-scale frequency converter

Advantage of DFIG or Type C wind turbine

Variable speed operation with a partial-rated converter

Advantage of Type D turbine

Full control of P and Q and no Gearbox but has larger power electronic converters (PECs) and higher costs.

What is the generator type used in Type D wind turbines?

SG: Synchronous Generator

What is a maintenance characteristic of Type D wind turbines?

Type D requires less maintenance but costs more.

What is a key feature of Type C wind turbines?

The PEC has a rating of only ~1/3 of the nominal power of the turbine.

What is the generator type used in Type C wind turbines?

DFIG: Double-Fed Induction Generator

V2G

Vehicle to Grid

SmartPark

EV inverter station acting as a grid resource (±25MW ≈ 1000 cars)

Disadvantages of SmartPark

Puts stress on grid capacity

Active Power control equation

P = 3/2 * (Vqs Iqs +Vds Ids)

Reactive Power control equation

Q = 3/2 * (Vqs Ids +Vds Iqs)

Something about laboratory implentation: Case studies

Fuzzy logic controller allows the wind turbine and smart park to stabilize the power output of their branch.
the controller decides to charge or discharge if the wind speed/generation increases or decreases

What is fuzzy systems

Reasoning method that allows partial truth values (between 0&1) rather than strictly binary yes/no logic

Equation of PV module equivalent circuit

Ia = Np * Isc (exp((VaIa*Rs)/(n * Ns * VT))-1)

Three types of Concentrated Solar Power (CSP)

Parabolic Trough (300 - 660F)
Tower (932 - 1832F)
Dish (480 - 1300F)

Building blocks of PVs

All in series:
Cell
Module
String
Array

MPPT

Maximum Power Point Tracking

What is Type 1 PV-System Architecture?

2 strings in parallel with 1 converter

What is Type 2 PV-System Architecture?

2 strings with dedicated converters

2 strings

2 converters

What is Type 3 PV-System Architecture?

2 strings with dedicated DC-DC converters and 1 system inverter

What is Type 4 PV-System Architecture

Modular with each panel having its own converter

What is a key advantage of Type 1 PV architecture?

Cheap

What is a key disadvantage of Type 1 PV architecture?

Very susceptible to failure

What is a key advantage of Type 2 PV architecture?

Less prone to failure

What is a key disadvantage of Type 2 PV architecture?

Slightly more expensive

What is a key disadvantage of Type 3 PV architecture?

More expensive and still prone to failure

What is a common issue with Type 3 PV architecture?

One common inverter has to fail

What is a key advantage of Type 4 PV architecture?

Modular

What is a key disadvantage of Type 4 PV architecture?

Very expensive

What has been implemented to stabilize generation from PVs

Particle Swarm Optimization (PSO)

Class definition of Smart grid

Smart grid is an advanced electrical network that uses digital communication

diagram of a smart grid

micro grids

Smart grid tech

Smart Park

Sandia model

Typical model that is used to predict PV performance

Computational Intelligence

Capable of taking large raw numerical sensory data directly

Types of Computational Intelligence

Artificial immune systems
Evolutionary computation
Fuzzy systems
Neural networks
Swarm intelligence
Hybrid systems

What is RNN

Recurrent Neural Network
Learns system behavior from data

Why is solar irradiance forecasting important

sudden irradiance changes cause fast PV output fluctuations

SAPM

Sandia Array Performance Model
Component-based and requires parameter tuning and physical modeling

Cellular Computational Network (CNN)

a distributed prediction model where each PV plant acts as a cell and shares information with its neighboring cells to improve short-term solar irradiance forecasting.

What makes the smart grid a "system of systems"

integrates computations

August 14

2003 blackout cause

What does DEMS stand for?

Dynamic Energy Management System

What is the goal of the Dynamic Energy Management System?

To have the grid be self-sustainable

What is the difference between D-Dems and I-Dems

D-Dems uses rule-based decisions

I-DEMS uses adaptive critic learning to make optimal real-time decisions.

How does DEMS provide stable/reliable power

Generation and storage must meet the load requirement.

What does DEMS aim to maximize in energy usage?

Renewable usage

How does DEMS aim to increase battery life?

By maximizing cycling times.

What is the potential of Adaptive Critic Designs?

Replicating brain-like intelligence

What are Adaptive Critic Designs created from?

Approximate dynamic programming

What are the two networks in an ACD

Action network and Critic Network

What is role of the Action Network in ACD

Dispenses control signals aka the actor

What is the role of the Critic Network in ACD

Learns the desired performance index

What does the Action and Critic network in ACD approximate?

The Hamilton-Jacobi-Bellman equation for optimization

What does I-DEMS stand for?

Intelligent DEMS

What two methods does I-DEMS combine?

Adaptive dynamic programming and reinforcement learning

What is the benefit of putting I-DEMS in parallel?

Improves convergence speed and near-optimal controls

What does LVQ stand for?

Learning Vector Quantization

What types of learning does Learning Vector Quantization use?

Unsupervised and supervised learning

In Learning Vector Quantization

what is assigned to each neuron in the first layer?

In Learning Vector Quantization

how is each class represented in the second layer?

Equation for LVQ network

W1i(q) = W1i(q-1) + a(p(q) - W1i(q-1))

What is the purpose of the LVQ second layer?

Used to combine subclasses into a single class.

LVQ is used for what in smart grids

Fault Classification and transmission line identification using PMU voltage-change patterns

How does the first layer of LVQ classify inputs

The neuron whose weight is closest to the input vector becomes the winner

In the LVQ second layer

what do the columns of w^2 represent?

In the LVQ second layer

what do the rows of w^2 represent?

What is a characteristic of each column in w^2 of the LVQ second layer?

Each column has a single 1 and all other values in the same column are 0.

Why are multiple neurons assigned to the same class in LVQ

to allow for complex

Wide Area Protection System (WAPS)

An LVQ network used to detect and isolate faults using wide-area voltage phasor data (PMU measurements)

What was the limitation of LVQ in WAPS

Difficultly distinguishing single-phase-to-ground faults -> required additional system features

tie lines definition

transmission lines that connect between areas

equations for a 12 bus system

What does DSOPF stand for?

Dynamic Security Optimal Power Flow.
It is a MIMO nonlinear optimal controller that replaces Automatic Generation and Regional voltage control

DSOPF is considered a MIMO controller because

it simultaneously adjusts multiple generator active power outputs

DSOPF uses what data

PMU and supervisory control and data acquisition (SCADA) wide-area measurement snapshots

Difference between SCADA and PMUs

SCADA samples in seconds and measures power flows & switch status
PMUs provide high-speed synchronized phasor measurements (30-120 samples/sec) for real-time grid monitoring

what does MIMO mean

Multiple input

What optimization does DSOPF provide?

Cost and loss optimization

How does DSOPF handle renewable energy variations?

By optimally rerouting the system's active and reactive power flow

What does DSOPF regulate

Frequency regulation

What are the special features of the smart grid compared to the legacy system

Bidirectional power flow.
Variability because of renewables.
Distributed generation

Why are traditional load flow techniques insufficient for smart grids

They assume centralized generation

different states of the power grid and what E and I are

E = equality Constraints
I = Inequality Constraints
Normal: E = satisfied

Disturbance sequence:

Normal->Alert->In-Extremis
or Normal->Alert->Emergency-> In-Extremis

Control Action Sequence:

Emergency->Alert->Normal

Restorative procedures sequence:

In-Extremis-> Restorative->Normal
or In-Extremis-> Restorative - > Alert