Phần 7 KHÓA ĐÀO TẠO TÍNH TOÁN ỔN ĐỊNH VÀ ỨNG DỤNG TRÊN PHẦN MỀM PSSE CHO KỸ SƯ HỆ THỐNG ĐIỆN (Nguyên tắc mô phỏng Ổn định động và các thư viện mô hình mô phỏng trên Phần mềm PSSE)

NGUYÊN TẮC MÔ PHỎNG ỔN ĐỊNH ĐỘNG VÀ CÁC THƯ VIỆN MÔ HÌNH MÔ PHỎNG TRÊN PHẦN MỀM PSSE. NỘI DUNG CHÍNH PHẦN 7 (Dynamic Simulation Principles) tiếp Phần 4: 1. Classification of Variables. 2. Dynamic Simulation Sequence. 3. Overview of Simulation Procedure.

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TRANSMISSION &

DISTRIBUTION

A Division of Global Power

POWER SYSTEM STABILITY CALCULATION TRAINING

D 3 D i Si l ti P i i l P t 2 Day 3 - Dynamic Simulation Principles Part 2

July 8, 2013 Prepared by: Mohamed El Chehaly

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2

OUTLINE

• Classification of Variables

• Dynamic Simulation Sequence

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CLASSIFICATION OF

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General Classification

4 CLASSIFICATION OF VARIABLES

General Classification

 Constants: Parameters that do not vary

 State variables: Variables for which

instantaneous values are determined by

differential equations

values can be determined if the values of all

state variables, constants, and input

 Input variables: Quantities for which values

the dynamic simulation

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Example of Power System Dynamic

m

n

D P

P dt

 Synchronous speed: ωsync = 1 p.u

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jX

jB jX

R

e jX

E

'

1 /

' '

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P

P dt

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Dynamic Simulation Arrays

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Data Space Allocation

 CON, VAR, STATE, ICON and DSTATE are

allocated to equipment models on a come, first-served basis.

P

P dt

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 The PSS®E coding for the last example:

DSTATE(L) (PMECH(I) PELEC(I)

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DYNAMIC SIMULATION

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Overall Flow Chart

18 DYNAMIC SIMULATION SEQUENCE

Overall Flow Chart

 Logic required to inform PSS®E of the

differential equations is provided by two

libraries of subroutines:

Handling models that involve state variables and

differential equations

Handling models that involve only algebraic

relationships between input and output signals p p p g

without reference to differential equations

 4 subroutines: TBLCNC, TBLCNT, CONEC

and CONET

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Dynamic Simulation Basic Flow

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Subroutines TBLCNC and CONEC

 Responsible for equipment models

involving state variables and differential

equations

 Responsible for time derivative of every

state variable

 Responsible for calculating the values of

all algebraic values of the state variable

time derivatives

 TBLCNC: responsible for machines and

their control systems

 CONEC: responsible for all other models

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Subroutines TBLCNT and CONET

 Responsible for equipment models in

which there is a purely algebraic

relationship between the voltage at a bus

and the current drawn by a device

 Responsible for equipment models for

which input or output is a quantity p p q y

determined solely by network quantities,

such as relays and monitoring models

 Principle equipment: shunt load devices

(reactors), relays and meters

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 Responsible for equipment models in

which there is a purely algebraic

relationship between the voltage at a bus

and the current drawn by a device

 Responsible for equipment models for

which input or output is a quantity p p q y

determined solely by network quantities,

such as relays and monitoring models

 Principle equipment: shunt load devices

(reactors), relays and meters

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Dynamic Simulation Control Flags

 MODE

1: Initialization Calculate initial condition values of

all state and algebraic variables

2: The model must make all computations needed

to place time derivatives into the DSTATE array

(stabilizers excitation limiters )

(stabilizers, excitation limiters,…)

3: Computation of output values of generator

source currents, exciter field voltages, turbine

mechanical powers, stabilizer outputs, excitation

limiter outputs

4: Apply special calculations in initialization of

induction motor and dc transmission models

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 MODE

1: Initialization Calculate initial condition values of

all state and algebraic variables

2: The model must make all computations needed

to place time derivatives into the DSTATE array

(stabilizers excitation limiters )

(stabilizers, excitation limiters,…)

3: Computation of output values of generator

source currents, exciter field voltages, turbine

mechanical powers, stabilizer outputs, excitation

limiter outputs

4: Apply special calculations in initialization of

induction motor and dc transmission models

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 MODE

5: Write model documentation when activity DOCU

is run in its report mode

6: Write model input data when activity DYDA is

run

7: Write mode documentation when activity DOCU

is run in its data checking mode

 TPAUSE

Time at which simulation is stopped

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 KPAUSE

0: Models are being called at a normal time step

1: Models are being called for the value of g

simulation time equal to

TPAUSE-2: Models are being called at a time step

immediately following a pause (TPAUSE+)

 SITER

Solution for the electric network given the machine

internal flux linkages and the load boundary

conditions

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 MSTATE

0: Standard simulation

1: Excitation system response ratio testy p

2: Excitation system open-circuit test

3: Governor test

4: Extended term dynamic simulation

5: Dynamics data is present but an initialization

activity has been successfully run

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CONEC and CONET during

g Initialization

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CONEC and CONET during

g Initialization

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CONEC and CONET during RUN

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Output Channel Control

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Channel Output File

 Binary file with name specified by user at

initialization

 Do not plot or tabulate the output channels

 Output channel values copied from the dynamic

simulation arrays by activity CHAN every NPLT

time steps

 NPLT is an integer specified by the user

 IPRINT is an array containing the addresses of s a a ay co ta g t e add esses o

the output variables

 IDENT is an array containing strings for each

t t i bl

output variable

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OVERVIEW OF SIMULATION

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Model Setup and Use

36 OVERVIEW OF SIMULATION PROCEDURE

1 Setup of a simulation model

a Valid CONEC and CONET subroutines

b Valid parameters and operating conditions for all

items of equipment

2 Execution of simulation runs using the

model as setup in the step 1 to show the

effects of proposed events such as

short-circuit faults, generator trips, or motor

starting g

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 Valid models will lead to correct

representation of the system following

disturbances

 A less-than-ideal model setup with

unchecked data will make simulation

runs more difficult and it will lead to

inaccurate results

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3 The initialization of the simulation at the

pre-disturbance network operating

condition is checked for model variables

initialized outside of prescribed limits

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Parameter Range Checking

 Activity DOCU

 Data checking mode

 Parameters are checked against typical ranges g yp g

of values

 Certain relational checks between parameters

 Suspect parameters are tabulated

 Flagged does not necessarily mean that values

are wrong

 Deserves to be checked

 If not flagged does not necessarily mean that gg y

values are correct

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 Activity DOCU

 Intended to detect gross errors

 Assumption is that plant equipment data is p p q p

specified on actual machine base MVA

 It is discouraged to specify all machine data on a

b

common base

 Strongly recommended to have correct machine

base (MBASE) in the power flow( ) p

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Performance Verification

 Check that the parameters of the

generator, excitation system and turbine

governor are correct by checking their

performance

 Set of parameter values lead to:

 Correct steady-state values of all quantities that

are normally measured or documented in normal operation of a generating unit

operation of a generating unit

 Correct reproduction of dynamic response tests

that may be performed on generating units and their control systems in isolation

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 Generator reactance and saturation data

 Generation saturation data is necessary in order

for the generator field voltage (EFD) to take on its correct value at all loadings

 Machine V-curves: plot generator terminal current

versus excitation voltage EFD over its whole

versus excitation voltage EFD over its whole operating range

 Provided by generator manufacturers along with

open circuit saturation curves

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 Exciter response ratio test

 Data describing the rotating exciter may be

checked by this test

 Exciter set up to run at the output voltage and

current corresponding to rated main generator operating point

 Voltage regulator setpoint is raised suddenly by a

large amount to drive the exciter to its ceiling as rapidly as possible

 Check the rated EFD, the ceiling value of EFD

and the excitation system response ratio

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 Exciter ceiling

 Ceiling voltage is the maximum direct voltage

that the excitation system is able to supply from its terminals (IEEE Std 421.2-1990)

 Ceiling field voltage determined mainly by the

saturation characteristic of the exciter and by the

saturation characteristic of the exciter and by the maximum output (DC exciter systems)

 Higher ceiling voltages tend to improve transient

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 Response ratio

 Also known as Nominal Response: the rate of

increase of the field voltage from rated value for

fd fd

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 Checked by ensuring that the excitation system

gives stable and effective control of generator terminal voltage when the machine is operating

terminal voltage when the machine is operating

at rated speed on open circuit

 Tested by applying a simple step change of about

five percent to the voltage regulator reference and observing the resulting responses of field voltages (EFD) and generator terminal voltage

voltages (EFD) and generator terminal voltage (ETERM)

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 Governor Response Test

 Principle purpose is to ensure that the governor

gain and time constant parameters correspond to

a correctly tuned well damped response

 Machine is initialized to a given load

 Response of the governors to a step change in

the load is measured

 The load electrical power is held constant after p

the step so that the response indicates the damping due to the turbine and governor loop only

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 The amount of speed (or frequency) change that

is necessary to cause the main prime mover control mechanism to move from fully closed to fully open

 Range between 3% and 7% (typically 4% or 5%)

 For example, a 5% droop means that a 5%

frequency deviation causes 100% change in valve position or power output

 10% change in load power leads to 0.5%

decrease in speed deviationdecrease in speed deviation

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 Speed droop

 With a speed droop of 4% how much will

 With a speed droop of 4%, how much will

a 5% decrease in power output reduce

the frequency? q y

100% change in power 4% change in frequency

5% change in power 0.2% change in frequency

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Simulation Model Setup

1 Load power system data in steady-state

2 Run power flow and ensure that a p

solution is found

3 Convert generators and load models

4 Select the appropriate model for each

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6 Load DYR file and prepare for dynamic

simulation

7 Set channels to monitor variables

8 Check all dynamic simulation data using

DOCU

9 Initialize and check all initial condition

suspects

10 Modify the model data

11.Ensure initial conditions are OK

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Execution of Simulation Runs

1 Establish and confirm initial conditions in

dynamic models (time initialized to t = - 2

x DELT)

2 Select and initialize dynamics output file

3 Advance simulation with no disturbance

4 Apply first action of disturbance

(application of fault)

5 Advance simulation to time of next

change of applied disturbance

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6 Apply next change of applied disturbance

(clear fault by opening a line)

7 Advance simulation to time at which no

additional results are currently needed

8 Stop dynamic simulation

9 Plot or tabulate results

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QUESTIONS?

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WE CARE about the health and safety of our employees, of those who work under our care, and

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Tiêu đề	Power System Stability Calculation Training
Tác giả	Mohamed El Chehaly
Trường học	Global Power
Chuyên ngành	Power System Stability
Thể loại	eBook
Năm xuất bản	2013
Thành phố	Unknown

Định dạng
Số trang	60
Dung lượng	2,88 MB