EMS-LECTURE 4: Network Analysis Functions

1.1 Introduction: Network Analysis F (NAFs) are important functions that constitute the working of an EMS. The

network analysis functions are employed to determine, update the system state and use it for

running programs to determine the security and stability of the power system. The various

Network Analysis functions can be listed as follows

Table 4.1: List of Network Analysis Functions

No Network Applications Function Description

1 Network Topology Processor: Building a network model based on real time

measurements

2 State Estimation Determining the best estimate from real time

measurements.

3 External Equivalent Equivalent of a Large scale system for studies

4 On-Line Power Flow Determining voltages and phase angles.

5 Security Assessment Determining the secure or insecure state of a

system.

6 Contingency Analysis Operation under faults or on unforeseen

contingencies

7 Optimal Power Flow Optimization of a specified objective function

with constraints.

8 Short Circuit Analysis Determination of fault currents for various faults

on the network

The network analysis functions use Real Time Modelling of the system. These are used in

Network Configuration Analysis, observability Analysis, State Estimation and Network

Application Functions. The Network Applications in an EMS, categorized into real time and

extended real time functions are given below

Real-Time Functions

Topological Analysis

State Estimation

Network Equivalent Calculation

Security Analysis

Generation Dispatch

Voltage and Reactive Optimization

Extended Real-Time Functions

Short term Load Forecast

Operator Load Flow

Short Circuit Calculation

The fundamental Functions in the EMS can be classified as

Primary Analysis (Perform decision making tasks)

Programs for Message Switching.

Control of Information Display Systems.

Recording of Status and events.

Information Processing for telecommand and control

Secondary Analysis(Operational planning tasks)

State Estimation

Optimal Power flow

Network Security Analysis

Load Prediction

Figure 4.1 shows the important applications programs in an energy control centre (ECC) or

Energy Management Systems (EMS). The following are the important points to be observed.

The following are the loops which describe the working

1. Loop / control that does not involve the operator

2. Loop / control that involves the operator for decision making.

On line closed loop control: (without operator)

- Automatic Generation Control

On line open loop control: (with operator)

- MWh one line monitoring

- MWh one line monitoring and Automatic Generation Control

- Other modules

Fig 4.1. Application Programs in an Energy Control Centre

Fig 4.2 Industrial Applications of Utilities.

Figure 4.2 shows the electrical utility industrial applications of EMS / SCADA. It can be

observed that EMS / SCADA form the first and the foremost stage in the industrial setup.

Automatic Meter Reading and Energy Trading are important functions which are employed in an

control centre.

Summary:

Important Network Analysis F (NAFs) are described in this section. NAFs are important

functions that constitute the working of an EMS. The network analysis functions are employed to

determine, update the system state and use it for running programs to determine the security and

stability of the power system.