Phần 20 KHÓA ĐÀO TẠO TÍNH TOÁN ỔN ĐỊNH VÀ ỨNG DỤNG TRÊN PHẦN MỀM PSSE CHO KỸ SƯ HỆ THỐNG ĐIỆN (Nghiên cứu ứng dụng Ổn định dài hạn trên Phần mềm PSSE)

Phần 20 KHÓA ĐÀO TẠO TÍNH TOÁN ỔN ĐỊNH VÀ ỨNG DỤNG TRÊN PHẦN MỀM PSSE CHO KỸ SƯ HỆ THỐNG ĐIỆN (Nghiên cứu ứng dụng Ổn định dài hạn trên Phần mềm PSSE)• LongTerm Stability in PSS®E• LongTerm Frequency Stability

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A Division of Global Power

POWER SYSTEM STABILITY CALCULATION TRAINING

D 9 A li ti f L T St bilit Day 9 - Application of Long-Term Stability

July 16, 2013 Prepared by: Mohamed El Chehaly

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OUTLINE OUTLINE

• Long-Term Stability in PSS®E

• Long-Term Frequency Stability

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LONG-TERM STABILITY IN PSS®E

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Long Term Stability

Long-Term Stability

 Simulation times ranging from many

seconds to several minutes

 The need to model additional effects not normally considered in stability runs of

normally considered in stability runs of several seconds

 Computer time requirements would be excessive

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Long Term Stability

Long-Term Stability

 If simulation time is extended to several

d

seconds

 Tendency of loads to exhibit constant power

characteristics through tap changers

 Automatic switching of reactors and shunt

capacitors

 Primary movers power changes through primary speed control and/or AGC (automatic generation control) and excitation limiters

 Detailed modeled of load restoration mechanisms and prime mover characteristics (boiler effects,

exhaust temperature effects on gas turbine…)

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Extended Term Module

 Additional module that has to be

purchased

 Includes the following:

 Augmentation of most equipment models

containing state variables to include an implicit

containing state variables to include an implicit integration algorithm technique for use in

performing extended term simulations

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On load Tap Changer OLTC1

On-load Tap Changer OLTC1

 Model for the transformer tap adjustments

to help control system voltage

 Two main components:

 Voltage sensor: if the voltage input is out of the

specified bandwidth, the control will operate after

specified bandwidth, the control will operate after the time delay has been exceeded

 Time delay circuit: enables the transformer to

correct only those voltage variations that exist for longer than a preset time

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On load Tap Changer OLTC1 On-load Tap Changer OLTC1

 Time delay = 30 seconds

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On load Tap Changer OLTC1 On-load Tap Changer OLTC1

 Model OLTC1 typical values

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On load Phase Shifter OLPS1

On-load Phase Shifter OLPS1

 Model for the automatic movement of taps

on phase-shifting transformers to control the power flow

 Same two components as OLTC1

 Only difference is that the input is real

power instead of voltage

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On load Phase Shifter OLPS1 On-load Phase Shifter OLPS1

 Model OLPS1 typical values

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Maximum Excitation Limiters MAXEX1 Maximum Excitation Limiters MAXEX1

 Designed to protect the generator field

with automatic excitation control from

overheating due to prolonged

overexcitation

 Overexcitation can be caused either by a

 Overexcitation can be caused either by a failure of a component of the voltage

regulators of an abnormal system

condition

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 Inverse time characteristics of MAXEX1

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 Block Diagram of MAXEX1

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 Model MAXEX1 typical values

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Steam Turbine and Boiler TGOV5

 Represents governor action, main, reheat and low-pressure effects, including boiler effects

 Can handle any mode of control including

 Can handle any mode of control including coordinated, base, variable pressure and conventional

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 Governor model

 Similar to IEEEG1 model

 Valve has rate limits as well as minimum and

 Valve has rate limits as well as minimum and maximum limits

 Steam flow is proportional to the product of the p p pthrottle pressure and the valve area

 Proper selection of time constants and gains allows the modeling of the reheater and

allows the modeling of the reheater and

intermediate and low pressure turbine effects

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 Fuel and boiler models

 Drum pressure (PD) is proportional to the integral

of steam generation less steam flow out of the

boiler

 Throttle pressure (PT) is equal to drum pressure less a pressure drop across superheaters and

steam leads

 The pressure drop varies as square of steam flow

 The pressure drop varies as square of steam flow and with density of steam

 The pressure drop coefficient is shown to be a

function of boiler pressure

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Steam Turbine and Boiler TGOV5 Steam Turbine and Boiler TGOV5

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 Conventional control

 Boiler follow mode: changes in generation are

initiated by turbine control valves

 Boiler controls respond with necessary control

action upon sensing the changes in steam flow

and deviations in pressure

 The turbine has access to the stored energy in the boiler

boiler

 Load changes within reasonable magnitudes with fairly rapid response

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 Turbine follow

 Use of the turbine control valves to regulate boiler pressure

 Can be done without time delay

 Boiler pressure suffers virtually no transient p y

 The response of turbine power is considerably

slower than conventional control

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 Coordinated optimal

 Recognize the advantages of the conventional and turbine follow modes

 Compromise between the desire for fast response

to load changes and the desire for boiler safety

and good quality control of steam conditions

 New demand signal modified by frequency

deviation to develop the desired MW Comparison with actual output develops MW errorp p

 Turbine-speed changer position is directed to

reduce a combination of MW error and pressure

terror to zero

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Steam Turbine and Boiler TGOV5 Steam Turbine and Boiler TGOV5

 Typical data for TGOV5

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Models (LDSH)

 LDSH type models

 LDSHBL: loads at a specific bus

 LDSHOW: loads with a specific owner

 LDSHZN: loads in a specific zone

 LDSHAR: loads in a specific area

 LDSHAL: all loads

 Represent solid-state type load-shedding relays based on low frequency

 Disconnect either a fraction of load or sets

flags to switch lines, capacitors…

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Models (LDSH)

 Load to be shed at each of three steps as

a fraction of the original load

 If the three load-shedding stages are set

 If the three load shedding stages are set

to shed 0.3 pu, 0.3 pu and 0.2 pu of the

multiplied by:

 1 – 0.3 on the first stage

 (0.7 – 0.3)/0.7 on the second stage

 (0.4 – 0.2)/0.4 on the third stage

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Models (LDSH)

 Underfrequency detection and load shedding

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Models (LDSH)

 Typical data for LDSHAL

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Models (LDSH)

 Model suffix

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 LVSH type models

 LVSHBL: loads at a specific bus

 LVSHOW: loads with a specific owner

 LVSHZN: loads in a specific zone

 LVSHAR: loads in a specific area

 LVSHAL: all loads

 Represent solid-state type load-shedding relays based on low voltage

 Disconnect either a fraction of load or sets

flags to switch lines, capacitors…

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 Typical data for LVSHAR

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 Protection models located at the generator

frequency on that bus or a remote bus

 Trip generator for under- and

over-frequency conditions on the generator

 Relay timer is started when frequency is

less/greater than or equal to the

corresponding threshold

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 Relay resets instantaneously if the

frequency restores within the two pickup thresholds (Fmin and Fmax)

 If the relay is not reset, a trip signal is

sent to the circuit breaker if the timer

reaches its setting (TP)

 Frequency must have remained outside of limits for the full duration for generator

limits for the full duration for generator

tripping

 Generator tripping is delayed by breaker

 Generator tripping is delayed by breaker time

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 Typical data for FRQDCAT

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 Protection models located at the generator

on that bus or a remote bus

 Trip generator for under- and over- voltage conditions on the generator

 Same principles as under/over frequency relays models (FRQDCAT)

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 Typical data for VTGDCAT

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DYR File for Long Term Stability

DYR File for Long-Term Stability

 Create a new DYR file “LT_Models.dyr”

 Use typical data for models defined in this presentation

 OLTC1T for transformers 152-153 and 205

204- OLPS1T for transformer 202-203

 MAXEX1 for all generators (101, 102, 206,

211, 3011 and 3018)

 TGOV5 for all steam generators (101, 102,

206, 3011 and 3018)

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DYR File for Long Term Stability

DYR File for Long-Term Stability

 LDSHAL for all loads (one statement only)

 LVSHAR for all loads in areas 1, 2 and 5

 VTGDCAT and FRQDCAT for all generators

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LONG-TERM FREQUENCY STABILITY

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Model Setup and Use

1 Open the case “Day5_savnw.sav”

Q = 450 MW)

3 Solve and make sure the case converges

4 Save the new case under

“Day9_savnw_LT.sav”

5 Perform the dynamic preparation steps

6 Save the new converted case under

“Day9_savnw_LT_cnv.sav”

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Long Term Frequency Stability Case

Long-Term Frequency Stability Case

1 Open the saved case

“Day9_savnw_LT_cnv.sav”

2 Open the dynamic file used for transient

stability “Day5 savnw dyr”

3 Add the new dynamic file

4 Prepare the dynamic solution parameters

and options

5 Monitor all the machine angles, bus

voltages, bus frequencies and power

loads

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6 Initialize and make sure initial conditions

k are ok

7 Run for 0 seconds

9 Trip machine at bus 101

11 View output progress

12 Open output channels to monitor the

impact

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Long Term Frequency Stability Case Long-Term Frequency Stability Case

6 Initialize and create a new output file

“Long-term frequency.out”

7 Make sure initial conditions are OK

10.Trip machine at bus 101

12 View output progress

13 Open output channels to monitor the

impact

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 Generator relays initiated

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 Load shedding relays initiated for low

frequency

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 Load shedding relays initiated for low

frequency

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 Load shedding stage 1

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 Load shedding

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 Frequency and voltage generator relay

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 Frequency and voltage generator trip

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 Frequency and voltage generator trip

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 Blackout

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QUESTIONS?

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Tiêu đề	Phần 20 Khóa Đào Tạo Tính Toán Ổn Định Và Ứng Dụng Trên Phần Mềm Psse Cho Kỹ Sư Hệ Thống Điện
Tác giả	Mohamed El Chehaly
Trường học	Global Power
Chuyên ngành	Power System Stability
Thể loại	Khóa đào tạo
Năm xuất bản	2013
Thành phố	N/A

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