In Course Assessment (ICA) for Smart Power Distribution [EAC4026-N]
This assessment takes the form of a report based on an analysis of the effect on the power distribution network of PV panels on a housing estate. You will be expected to perform independent research in addition to the load flow analysis using the software.
You should write a report based on the requirements of the attached brief and this should be an individual submission. This assessment counts for 30% of the total module marks.
The assessment criteria will be the standard University level 7 criteria assessing all learning outcomes (1-7) from the module specification
The marking criterion for each section of the report will follow the School’s standard guidelines, which will also be used for providing feedback. An example of the template, together with weightings, is provided at the end of this brief.
Structure of the Report
The report should adhere to the following guidance:
- The report should have a title page and a contents page, and each page should be numbered.
- Aside from the title and contents pages, the report should be a maximum of 20 pages (2000 words or equivalent) long including equations, figures, illustrations and tables. An abstract should be included together with your findings as a conclusion.
- Reports exceeding this page limit will face a penalty of a 20% deduction in the achieved marks.
- One additional page may be used to list references – which should follow the Harvard standard.
- Figures and tables should be numbered and should have a caption describing the figure/table. The caption should also indicate the primary feature that should be observed by viewing the figure/table. Figures should also be neat and of a readable size. (Note screen shots for showing power flow analysis outputs are difficult to read use the snipping tool). Tabulating results for comparison add value to the analysis.
- Brevity is commendable. Appendices should be used for additional information such as extracts from data sheets. It is important that the report be readable and understandable without reference to the appendices
If any parts of the exercise are unclear, please ask the module team for clarification.
Design and Analysis of Medium Voltage Distribution Networks Incorporating High Level of Embedded Generation
The continuous increase in embedded generation, particularly from renewable energy, connected at various locations on the distribution network can have implications for voltage control and quality of supply. Typical problems associated with embedded generation are voltage rise beyond the statutory limits, increase of fault levels, reverse power flow in the network and possible malfunction of the network protection system. Dealing with such problems requires a good understanding of the system behaviour under different operating conditions and an evolution from a traditional passive network control philosophy to a fully active network management and control.
A key step in understanding and consequently solving the problems associated with large penetration of embedded generation into the MV (Medium Voltage) network is to develop a computer model of a typical MV network incorporating different types and levels of embedded generation.
2. Context of the assignment
A housing developer is proposing to install a new housing development onto the MV network on a local 11 LV busbar near the site. They have finally woken up to the need for Small Scale Embedded Generation (SSEG) on their homes and intend to install PV panels on every house. Your job is to write a report analyzing the effects this may have on the MV network in order to support the developer’s application for a connection agreement with the DNO (Distribution Network Operators).
The report needs to analyse the effects of a significant level of embedded generation on the performance of MV distribution network; mainly voltage profile, thermal overload of lines and transformers, as well as reverse power flow in the network.
- A computer model of network using IPSA+ software package should be developed and should be used as the basis for performance evaluation.
- The network model should include models of embedded generators connected to the low voltage side of the distribution network co-terminally to the loads.
- The model should then be used to study the effects of embedded generation on the steady-state performance of the distribution network; that is voltage profile, meeting thermal limits and reverse power flow.
- It should compare the power flow for all the scenarios needed to consider the implications for the DNO
- The results of the modelling should be analysed and recommendations made to alter the design if necessary,
- Allow the developer to give the necessary power requirements to the DNO.
3. LV Network Modelling
To analyse the impacts of SSEG on the LV network, a distribution network model needs to be developed using IPSA software package. This network model should include the distribution network from the primary voltage level (33 kV) down to the 0.4 kV level. The model should
allow simulation of 3-phase operation and different sizes of loads and SSEGs. Standard load flow is fine, MVA base is 10 MVA, use the Universal machine for the SSEG components.
First you need to analyse the effect of the extra load on the network, that is due to the extra feeder.
To analyse the performance of the distribution network with PV, the penetration of PV systems is varied from 0 to 100%. The PV systems are uniformly distributed across three phases and are evenly spread along the feeder/distribution network. PV is installed on each house in bus 6 to bus 1; bus 6 is the farthest from the substation.
The distribution network is either at minimum loading condition of 152 W at 0.95 pf lagging or at 500 W at 0.95 pf lagging (the daytime minimum load being higher than the after diversity minimum demand of the distribution network).
The on-load tap changer at 33 kV controls the tap settings depending on the loading of the distribution network and is set to maintain the secondary voltage of the LV transformer at 433/250 V.
Network to be modelled
A sample distribution network which is part of an actual network in the UK is chosen for analysis.
Figure 1 network to be modelled
One low-voltage feeder (supplied from a 750 kVA transformer) together with its connected loads is modelled in detail. The other three low-voltage feeders, supplying 327 houses, are modelled as lumped load as shown in Fig. 1.
The detailed feeder has 60 houses distributed uniformly across all the phases from the substation. Buses 5 and 6 are split feeders from bus 4.
Table 1 Details of number of houses per bus per phase
|Number of houses||4||3||5||2||4||2|
The details of the number of houses at each bus are given in Table 1.
The after diversity maximum demand ADMD for the network under consideration is 1.3 kVA. This figure can be used for the 11 kV lumped loads
The distribution network including the on-load tap changer at 33 kV is to be modelled in IPSA. PV systems with individual capacity of 2.5 kWp are chosen as it is close to the average individual PV system capacity in the range of 0–4 kW installed in the UK.
The PV system comprises ten PV modules/panels of 250 Wp each connected in series and then connected to an inverter of 2.5 kVA rating. The inverter has a nominal rating which is same as the total module rating, with unity power factor.
- A 33 kV three-phase source representing the grid supply ensuring the constant (slack bus) voltage of 1.0 per unit.
- The MV substation comprises two 25 MVA, 33/11.5 kV delta star transformers equipped with on-load tap changers. The substation has six 11 kV outgoing feeders. Five feeders together with their connected loads are modelled as a lumped load connected to the main 11 kV busbar.
- One 11 kV outgoing feeder connects to a local 11kV bus by 3 km of overhead line (185 mm2 3-core XLPE Cu cable). At the mid point, 8 LV transformers with identical loads are connected. The 9th feeder is detailed from here. This local bus connects to the Low Voltage (LV) 11/0.433 kV substation. This supplies four identical feeders.
Detailed 400 V feeder
- Each feeder is 2 km long, of 95 mm2 3-core XLPE Cu cable with the LV transformer at the end.
- The LV substation supplies customers at 400 V.
- The homes are all fitted with a PV system, rated at 2.5 kW
- The loads are assumed to be equally distributed in three phases.
4. Network details
33/11 kV Transformer Capacity: 25 MVA Each Impedance 12% on rating X/R = 15
Tap Changing: -20% Min, +10% Max
3.0 km of 185 mm2 3-core XLPE Cu cable and 2.0 km of 95 mm2 3-core XLPE Cu cable 185 mm XLPE Cu Cable: R = 0.128 Ω/km and X = 0.091 Ω/km
95 mm XLPE Cu Cable: R = 0.0106 Ω/km and X = 0.0075 Ω/km
11/0.4 kV Transformer
Capacity: 250 kVA
Impedance 20% on 10 MVA base R negligible
Tap Changing: none
For each house/customer
Minimum Load: 152 W 0.95 p.f. lag
Minimum daytime load: 500 W @0.95 p.f. lag Maximum Load: 2.0 kW 0.9 p.f.
Minimum PV system size: 0 kW Maximum PV system size: 2.5 kW Assignment Requirements
- To construct, using IPSA+ software, the network described and analyse the power flow.
Describe the power flow. Check the steady state power quality for breaches to statutory regulations. Repeat for each scenario. Make recommendations for changes to the design to meet regulations if necessary.
- To write a report (a text maximum of 2000 words, excluding diagrams, contents, references etc.) to include theoretical background, details of the simulation conducted, results obtained, critical discussion and conclusions. High standards of presentation are required. It is expected that the quality of the network model can be assessed by attaching it as an appendix to the report. Untidy or disorganized reports will be penalised. While you may work on the network model with others, the report must be your own work; you must not copy from others. Also, any reference material you use must be acknowledged.
- To submit the report before 4 pm on the 20th April 2021
- Access to remote Computers and IPSA+ software package via Apps Anywhere.
- Access to staff and PG student advice
- N. Jenkins, R. Allan, P. Crossley, D. Kirschen and G. Strbac, “Embedded Generation”, IEE Power and Energy series, London, UK. 2000. ISBN number 0852967748.
- Sivapriya Bhagavathy, Nicola Pearsall, Ghanim Putrus, Performance assessment of a three-phase distribution network with multiple residential single-phase PV systems, CIRED, Open Access Proc. J., 2017, Vol. 2017, Iss. 1, pp. 2480–2483
This assignment is worth 30% of the assessment for this module – a notional 60 hours work
Allocation of Marks
Presentation and structure of the report – 5% Preparation for using IPSA from weeks 2-4 labs – 3% Executive summary – 10%
Appropriate theoretical research (maximum of three pages) – 15% Technical analysis and findings appropriate to the task – 60% Conclusions – 5%
References – 2%
School of Science & Engineering Assessment Feedback Sheet
|Title||Smart Power Distribution|
|HIGH QUALITY INDICATORS||GRADE/CLASSIFICATION||POOR QUALITY INDICATORS|
|Structure: Report reads like a consultant’s feasibility study with appropriate use of tables, graphs, diagrams and subsections. It includes an executive summary and references||20%||☐||☐||☐||☐||Poorly structured report with inappropriate or missing tables, graphs, diagrams. No summary of findings, no evidence of prep work for IPSA|
|Research: Comprehensive review of literature relevant to study with a detailed knowledge of issues relating to case study demonstrated.||15%||☐||☐||☐||☐||Little or no evidence of literature review, may be irrelevant to the study and limited knowledge of subject area demonstrated.|
|Measured values: All necessary values to satisfy the brief are modelled with correct justification of the assumptions, demonstrating an understanding of values and limitations of the method.||20%||☐||☐||☐||☐||Incomplete or inaccurate model showing incorrect values with no understanding of limitations of the method.|
|Technical Design Calculation: Detailed design of PV system combined with appropriate technical analysis.||20%||☐||☐||☐||☐||Partial results for only one scenario. No analysis|
|Discussion/Conclusions: Clear discussion of active network control with logical conclusions based on evidence and a competent critical analysis.||25%||☐||☐||☐||☐||Discussion of findings is poor or missing, conclusions are not supported by the evidence, No control analysis.|
D = 100-70%, M = 69-60%, P = 59-50%, F = 49-0%
|ENGLISH AND PRESENTATION (the following areas need care and attention)|
|Spelling||☐||Figures and Tables||☐||References||☐|
|Final Mark||/100||Marked by:|