Download Dynamic stability analysis and more Lab Reports Power Distribution and Utilization in PDF only on Docsity!
POWER SYSTEM OPERATION AND CONTROL
LABORATORY MANUAL 9 (Part A and Part B) KASHAF ABDULLAH 2019EE Stability Analysis for Grid Impact of Wind Farms using Type 3 and Type 4 WTGs Course Learning Outcome (CLO) CLO: ‘Demonstrate the power system stability and control using software tools’ Problem Statement A network comprising seven buses as designed in Lab # 6 will be used as a base case. In this lab, we will incorporate a ‘Wind Farm’ to an existing base case. Further, dynamic study will be conducted and variation in pitch angle of wind turbine will be observed. The tasks of this laboratory are to be covered in three phases:
- Modeling and integration of renewable energy (RE) sources
- Preparation of dynamic load flows for stability simulations
- Defining channels for important variables to be monitored Reading Material Overview of Wind Turbine Technologies Initial use of wind energy finds its traces in Holland. Many different types of wind generators are used world wide; namely, Type 1 (Direct connected conventional induction generator), Type 2 (Wound rotor induction generator with variable rotor resistance), Type 3 (Doubly-fed induction generator), and Type 4 (Full size converter unit) but most commonly WTG-3 and WTG-4 (i.e., Type 3 and Type 4) are used. Type 1 and Type 2 have fixed speed operation and therefore, harnessing of maximum power is not possible. Unlike conventional generators, wind generators are basically induction generators (IGs) and thus they affect system frequency a lot. IG absorb reactive power and capacitors are added in order to compensate reactive power consumption. Since, wind generators are widely affected by the air turbulence, wind speed, torques which are continuously varying factors, thus the power generated by the wind turbines is also varying.
WTG-3 type wind generators (Doubly Fed Induction Generators) incorporate special control system, which controls the speed of rotor (putting in use the complicated mechanical gear boxes) by taking feedback from stator to develop a strong interconnection between grid parameters and wind mechanical parameters. In WTG-3 type generators, mechanical gear box requires continuous maintenance, and small changes in wind speed results in bigger torque changes. Maximum harnessing of power is achievable as speed can be changed by 40 %. ( Reference: Chapter 22, Program Application Guide PAG2, you can find it in the folder PTI → Docs where PSS/E has been installed ) WTG-4 type wind generators use full converters which act as a buffer and thus, grid frequency and voltages are de-coupled. Modelling of PV Solar is quite identical to WTG-4 type generator. Spacing between wind- turbines is another critical parameter due to air turbulence. When air leaves one turbine, and while entering second turbine, it is not smooth. The second turbine will not have that much good quality of imput wind ( also known as Wake Effect ) Concept of Collector Groups Wind generators are quite small in size if compared with the hydel and thermal generators and are distributed throughout the area, to gain more stability and reliability. The distributed wind generators are clustered as collector groups to minimize power losses. A collector group is a set of 8 to 12 wind generators, in the same area generating power within the same range. Example For example, in order to install a wind farm having gross capacity = 50 MW, if MW rating of 1 WTG is 1. MW, and total number of WTGs are 33, then 4 collector groups can be assigned having 8,8,8, and 9 WTGs, respecitvely. A collector group of 8 machines can be incorporated into a single machine ( in PSS/E). If there are multiple wind farms, and study of 1 farm is to be conducted, so collector groups of farm (under study) will be made; and for rest of the farms, equivalent one machine can be created. LV for WTG is 0.62 kV – 0.69 kV, and MV for WTG is 11 kV – 33 kV. Midpoint is chosen for power extraction from each collector group to minimize the losses. After gathering power at substation, it is stepped-up and interfaced with grid at 132 kV. At this voltage level, PFCC is connected to locally compensate all the collector groups. (SLD of ‘Typical Wind Farm Layout’ with 5 collector groups can be accessed from MS Teams →Files Section)
Power Factor Leading 0. Lagging 0. Collector Group Number of Collector Groups 2 Number of WTGs in Collector Group 1 9 Number of WTGs in Collector Group 2 8 Data of Wind Turbine Step Up Transformer Number of Transformers 17 Voltage Ratio in kV 0.69/ MVA Rating of Transformer 1.75 MVA Percentage Impedance of GSU 6% Data of Power Transformer Number of Transformer 1 MVA Rating of Transformer 40 Percentage Impedance of Transformer 12.50% Collector Cables length of Collector Group-1 in Km 3 length of Collector Group-2 in Km 1 MVA rating of Cables 9. R=0.025225, X=0.02458, B=0.00003 (per Km) Data of 132 kV Transmission Line Number of Circuits 1 Length of Single Circuit 10 Type of Conductor Lynx Reactive Power Compensation Shunt Capacitor 10 MVAR Task 9-A: Load Flow Analysis of Base Case with Wind Farm Data
Wind Machine Data Record (WTG) Collector Group - 1 (9 Wind Generators) Pgen 9 x 1.5 MW=13.5 MW Pmax 1.05Pgen^ (i.e., additional 5% of Pgen) =^ 14.175^ MW Pmin 0.33Pgen^ (33% of Pgen)^ =^ 4.455^ MW Qgen No need to specify Qmax No need to specify Qmin No need to specify 𝑷. 𝑭 0. Mbase 𝑃
𝑔𝑒𝑛 = 14.21 MVA
Xsource 0.8 p.u. for WTG model 9999 p.u for Solar Xtran 0 (explicit modelling) Vsched (slightly higher than 1 pu for PV bus) = 1.
Ratings Rate 1 = MVA from WT data table = 9.9 MVA Collector Cables B: 1 Km R (positive sequence) = 0.025225 pu X (positive sequence) = 0.02458 pu B (positive sequence) = 0.00003 pu Length (as per SLD) = 1K m Ratings Rate 1 = MVA from WT data table = 9.9 MVA Note: Enter the line length in excel file before using the line parameters. Transformer Data Record Ratings of WTG Step-up Transformer: Xpu: 6% given as per 1.75 MVA base. For 100 MVA base, 𝑋𝑝𝑢−𝑛𝑒𝑤 = 𝑋𝑝𝑢−𝑜𝑙𝑑 × (𝑆𝑛𝑒𝑤 𝑆𝑜𝑙𝑑 ) As transformers corresponding to 8 and 9 collector groups have been merged therefore, 𝑋𝑝𝑢−𝑛𝑒𝑤 𝑋𝑝𝑢_𝑓𝑖𝑛𝑎𝑙 = 𝑁𝑜. 𝑜𝑓 𝑐𝑜𝑙𝑙𝑒𝑐𝑡𝑜𝑟 𝑔𝑟𝑜𝑢𝑝𝑠 (8 𝑜𝑟 9) Generation StepUp Transformer (132/20 kV) Reactance: 12.50 % at 40 MVA Base Rated MVA = 36/40 MVA X = 0.35 pu (For rated MVA and the indicated value of reactance in %, enter X at 100 MVA base) Ratings Rate 1 = Rated MVA (upper limit) = 40 MVA Wind Generator Step Up Transformers (0.69/20kV) for Collector Group - A Reactance: 6% at 1.75 MVA Base Rated MVA = 1.75 MVA X = 0.38095 pu (For rated MVA and the indicated value of reactance in %, enter X at 100 MVA base) Ratings Rate 1 = Rated MVA (upper limit) = 15.75 MVA
Wind Generator Step Up Transformers (0.69/20kV) for Collector Group - B Reactance: 6% at 1.75 MVA Base Rated MVA = 1.75 MVA X = 0.428571 pu (For rated MVA and the indicated value of reactance in %, enter X at 100 MVA base) Ratings Rate 1 = Rated MVA (upper limit) = 14 MVA Load Data Record An additional load of 25 MW and 10 MVAR is added at Bus B (132 kV) Load - D Pload = 25 MW Qload = 10 MVAR Switched Shunt Data Record Add fixed shunt of 10 MVAR at Bus-I. Load Flow Results Attach the results of load flow in the space provided.
To convert the load flow, follow these steps:
1. Go to “Power Flow” 2. Click on “Convert Loads and Generators” **Add snapshot of converted values of loads (in Network Case Data file)
- Go to ‘Power Flow’ → click on ‘Solution’ → click on ‘Order network for matrix Operation** **(ORDR)’
- Go to ‘Power Flow’ → Click on ‘Solution’ → Click on ‘Factorize Admittance Matrix (FACT)’**
5. Go to ‘Power Flow’ → Click on ‘Solution’ → Click on ‘Solution for switching studies (TYSL)’ Save this file with extension ‘.cnv’. The saved file is Converted Load Flow. Note: For performing dynamic studies, you are supposed to perform above 5 steps always. And then you have to call ‘.cnv’ case instead of ‘.sav’ case. Entering Dynamic Data related to Network
- Open a Text document file
- Rename it and change its extension to ‘.dyr’
- Open the ‘.dyr’ file in PSS/E
Generator Model: WT3G1 Parameters Con description Con Values Xeq- equivalent reactance for current injection 0. PLL gain 30. PLL integrator gain 0. PLL maximum limit 0. Turbine MW rating 1. Model ICONS Number of lumped wind turbines 8/9 (for 8 and 9 collector groups)
- Click on “Electrical”, and select “WT3E1” and enter the model parameters as shown below:
Electrical Model: WT3E1 (Feedback Loop) Parameters
T_POWER - Power filter time constant, seconds
- Tfv - V-regulator filter 0. Con description Con Values
- Kpv - V-regulator proportional gain 18.
- Kiv - V-regulator integrator gain 5.
- Xc - line drop compensation reactance; suggested
- Tfp - T-regulator filter, seconds (>0) 0.
- Kpp - T-regulator proportional gain 3.
- Kip - T-regulator integrator gain 0.
- PMX - T-regulator max limit 1.
- PMN - T-regulator min limit 0.
- QMX - V-regulator max limit 0.
- QMN - V-regulator min limit - 0.
- IPMAX - Max active current limit 1.
- TRV - V-sensor 0.
- RPMX - maximum Pordr derivative 0.
- RPMN - minimum Pordr derivative - 0.
- KQi - MVAR/Volt gain 0.
- Click on “Mechanical” and enter the parameters:
- Click on “Pitch” and enter the parameters
- Now in order to declare Machine at Bus A as Thermal Machine (GENROU) and Machine at Bus C (Swing) as Hydel machine (GENSAL), insert the parameters from the word file ‘Stability Models for Hydel and Thermal Power Plants’ [MS Teams → Files Section] for generator, exciter, and turbine.
- Save the snapshot file (e.g., lab9.snp)
- Go to “Dynamics”. Click on “Models List” and then click on “Models and Data”. It will list dynamic data of various models for all buses.
WT3G
- Go to View → Tool bars → Dynamic Simulation In part C of this manual, we’ll add channels (just like scope), to view outputs of various parameters by introducing fault at any bus. Laboratory Manual 9 (Part A and Part B) Rubrics Task No. Component Name Marks Allocation Marks Obtained
9 - A
(Renewable Energy Resource Modelling) Converged Load Flow
Total 9-A 6 9 - B (Converted Load Flow & Data Preparation for Dynamic Stability) Converted Loads
Listing Dynamic Data for WTGs
Total 9-B 14 Grand Total 20
