Electric Vehicle Charging Station Location using Fuzzy Optimization

Electric vehicle charging station location is a basic problem in integrating electric vehicles in electric power systems. An electric vehicle plugged into the electric distribution system may absorb or produce active and/or reactive power [1-4] depending on the need of the electric power system, Table 1 below.

Electric vehicle charger operating modes [4].

When finding the location of EV charging stations in order to support the electric distribution systems, the cost of EV charging, the impact on distribution system losses and voltage profile of the system are parameters needed to be considered. These variables are to be looked into when plugged in EV is either acting as a generator or a load given a system demand level.

Recent studies have solved this EV charging station location problem. In [5], a mixed integer programming solution was developed with site accessibility, local jobs and population densities and trip attributes as main constraints. A genetic programming approach is utilized in [6] for simulation of electric vehicles on a real map of a European city where the optimal solution of the charging infrastructure is derived based on mean trip times of electric vehicles. A two step procedure is proposed in [7] where the authors included environmental factors and service radius of EV charging stations in the screening first step and built a modified primal-dual interior point algorithm (MPDIPA) for optimal sizing of EV charging stations with the minimization of total cost associated with EV charging stations to be planned as the objective function with losses and voltage profile included in the problem. Reference [8] introduces an optimization process for sizing and siting of EV charging stations, modeling the charging demand and the structure of road network to where the solution approach was graph theory. Level 1 and level 2 charging stations are discussed in [9] and how to allocate them for residential EV users using simulation-optimization strategy.

Recent studies do not consider uncertainties and imprecision which can be captured using fuzzy optimization. Fuzzy set theory can provide a simpler yet powerful solution for allocating EV charging stations in electric distribution systems. The Civanlar test system [11] will be utilized for the study and assuming that capital investment of the EV charging station is the same for all distribution system candidate nodes while considering time of use (TOU) electricity tariff, distribution system losses and voltage profiles.

References

[1] Chenye Wu, Hamed Mohsenian-Rad, and Jianwei Huang, “PEV-based Reactive Power Compensation for Wind DG Units: A Stackelberg Game Approach”, in Proc. of the IEEE Conference on Smart Grid Communications (SmartGridComm’12), Tainan City, Taiwan, October 2012.

[2]   Chenye Wu, Hamed Mohsenian-Rad, Jianwei Huang, Juri Jatskevich, “PEV-Based Combined Frequency and Voltage Regulation for Smart Grid”, the 3rd IEEE Innovative Smart Grid Technologies Conference, Washington DC, Jan 2012.

[3]    M. Kisacikoglu, B. Ozpineci, L. M. Tolbert, "V2G Reactive Power Compensation Using a PHEV Bidirectional Charger Interface Rated at Level 1, 2, and 3 Charging Standards," IEEE Energy Conversion Congress and Exposition, Atlanta, Georgia, Sept. 12-16, 2010.

[4]     M. Kisacikoglu, B. Ozpineci, L. M. Tolbert, "Examination of a PHEV Bidirectional Charger System for V2G Reactive Power Compensation," IEEE Applied Power Electronics Conference, Palm Springs, California, Feb. 21-25, 2010, pp. 458-465.

[5]    Chen, T. D., et al, “The Electric Vehicle Charging Station Location Problem: A Parking-Based Assignment Method for Seattle”, on-line: http://www.caee.utexas.edu/prof/kockelman/public_html/TRB13EVparking.pdf

[6]    Hess, A. Et al, “Optimal Deployment of Charging Stations for Electric Vehicular Networks”, on-line:http://conferences.sigcomm.org/co-next/2012/eproceedings/urbane/p1.pdf

[7]    Liu, Zhipeng, Wen, F. and  Ledwich, G. F. , “Optimal Planning of Electric-Vehicle Charging Stations in Distribution Systems”, IEEE Transactions on Power Delivery, Jan. 2013, Vol. 28 , Issue 1.

[8]    Jia, L., Hu, Z., Song, Y., Luo, Z., “Optimal siting and sizing of electric vehicle charging stations”, 2012 IEEE International Electric Vehicle Conference (IEVC), 4-8 March 2012

[9]    Xi, X., et al, “Simulation-Optimization Model for Location of a Public Electric Vehicle Charging Infrastructure”, on-line:http://www.ise.osu.edu/ISEFaculty/sioshansi/papers/charge_infra.pdf

[10]“Siting Electric Vehicle Charging Stations”, on-line: http://www.sustainabletransportationstrategies.com/wp-content/uploads/2012/05/Siting-EV-Charging-Stations-Version-1.0.pdf

[11]On-line: http://ee.sharif.ir/~e_hajipour/index_files/Test_Cases_Data.pdf

Voltage Stability Impact of Electric Vehicles

Reactive power consumption or injection is a promising feature out of electric vehicle charging. In [1] and [2], the authors present the analysis of the  reactive power control capability of an electric vehicle charging system to support the power system. Reactive power support and economics from the electric vehicles were discussed in references [3] and [4].

The electric vehicle charger follows the modes of operation [1]:

Electric vehicle charger operating modes [1].

Given these modes, analyzing power system voltage stability with electric vehicle charging would be needed. PV and QV curves will be helpful to assess the impact of the different charger operating modes as well as transient voltage stability simulations. This would be a welcome addition to the increasing literature of vehicle to grid (V2G) especially when the grid operator coordinates a large fleet of electric vehicle with the power network.

Does the electric vehicle charging mode provide increased power transfer in terms of static voltage stability? Does the operating mode of an electric vehicle charger gives a better voltage recovery during transient periods?

These research questions can be analyzed by modeling electric vehicle charging operating modes integrated in a power system test case.

References:

1. M. Kisacikoglu, B. Ozpineci, L. M. Tolbert, "V2G Reactive Power Compensation Using a PHEV Bidirectional Charger Interface Rated at Level 1, 2, and 3 Charging Standards," IEEE Energy Conversion Congress and Exposition, Atlanta, Georgia, Sept. 12-16, 2010.
2. M. Kisacikoglu, B. Ozpineci, L. M. Tolbert, "Examination of a PHEV Bidirectional Charger System for V2G Reactive Power Compensation," IEEE Applied Power Electronics Conference, Palm Springs, California, Feb. 21-25, 2010, pp. 458-465.
3. Chenye Wu, Hamed Mohsenian-Rad, and Jianwei Huang, “PEV-based Reactive Power Compensation for Wind DG Units: A Stackelberg Game Approach”, in Proc. of the IEEE Conference on Smart Grid Communications (SmartGridComm’12), Tainan City, Taiwan, October 2012.
4. Chenye Wu, Hamed Mohsenian-Rad, Jianwei Huang, Juri Jatskevich, PEV-Based Combined Frequency and Voltage Regulation for Smart Grid, the 3rd IEEE Innovative Smart Grid Technologies Conference, Washington DC, Jan 2012.

Benefits from Electric Vehicles for the Philippine Power Grid

The last blogs I posted on electric vehicles (EV) may seem to have created the wrong impression in what I’m trying to do. I analyzed the loading impacts of E-Jeepneys and E-Trike to local electric distribution power system, specifically loading up a pole mounted distribution transformer. In practice, these scenarios are very real and can be prevented by planning and coordinating new loads which are the EVs under the government’s program.

The overloading of electrical equipment, at least locally, is just one tiny bit on one side of the fence. EVs when largely manufactured and utilized can be a resource of power grid reliability and security support, just like any other ancillary services.

References [1-4] provide simulations and analysis on the following:

• Frequency regulation – NGCP procures frequency regulation from on-line generators which are called spinning reserves. A big bulk of load can be aggregated and adjust accordingly to maintain system frequency, like a spinning generating reserve. I posted that the vision of DOE to have 100,000 E-Trikes by 2017 will have a MW load greater than the Quezon Power plant which is 480 MW. EV charging is via power electronic converters/inverters which are controllable. The charging of E-Trikes if coordinated accordingly to serve a load serving as a spinning reserve is a promising capability for E-Trikes or any large scale electric vehicle when aggregated.

• Reactive power compensation – Again, NGCP installs and may procure voltage support services from generation or invest on its own reactive power devices. In [3], the authors described an EV charging system which can be a source of reactive power compensation. This system is allowed to inject or consume reactive power whichever is needed by the power system in real time. In [4], the authors provided a pricing methodology for wind farm reactive compensation provided by an EV charging park.

• Contribution to system security – NGCP procures contingency reserves per Philippine Grid Code.  These are generators which are on-line ready to respond (increase or decrease their output) in times of a system disturbance. Authors in reference [2] indicate that EV chargers have response time faster than generators. In this case, going back to the 100,000 E-Trike, you may have a large “generator” providing that contingency reserve to mitigate any undesirable system condition due to a disturbance.

For large scale E-Trike or E-Jeepney charging, which is envisioned in the Philippines, these features would become income generating resources for EV operators or aggregators. Also, the NGCP will have another source of ancillary services which can be counted upon to support grid reliability and security.

References:
[1]    Chenye Wu, Hamed Mohsenian-Rad, Jianwei Huang, Juri Jatskevich, “PEV-Based Combined Frequency and Voltage Regulation for Smart Grid”, in Proc. of the IEEE PES Innovative Smart Grid Technologies Conference (ISGT’2012), Washington, DC, January 2012.
[2]    Sakis Meliopoulos, Jerome Meisel, George Cokkinides and Thomas Overbye, "Power System Level Impacts of Plug-In Hybrid Vehicles." PSERC Document 09-12, PSERC Final Report. October 2009.
[3]    M. Kisacikoglu, B. Ozpineci, L. M. Tolbert, "Examination of a PHEV Bidirectional Charger System for V2G Reactive Power Compensation," IEEE Applied Power Electronics Conference, Palm Springs, California, Feb. 21-25, 2010, pp. 458-465.
[4]    Chenye Wu, Hamed Mohsenian-Rad, and Jianwei Huang, “PEV-based Reactive Power Compensation for Wind DG Units: A Stackelberg Game Approach”, accepted for publication in Proc. of the IEEE Conference on Smart Grid Communications (SmartGridComm’12), Tainan City, Taiwan, October 2012.

E-Trike: Impact on Distribution Transformer Loading

The partnership of DOE and ADB envisions having 100,000 E-Trikes between now and 2017 [1]. Each E-Trike will have about 3 kW to 5 kW electric power usage and will be charging for about 45 minutes to 1 hour.

A study by DOE in collaboration with United Nations [2] indicated that one E-Trike will consume 1.8 MWh in one year. So to check the values here: 1.8 MWh divided by 365 days, an E-Trike will take 4.93 kWh. Below is a table for the kW loading of E-Trike(s). Note that 100,000 E-Trikes is even above the capacity of Quezon Power plant which has 480 MW capacity.

In this post, several scenarios of charging time and number of E-Trikes are presented using 4.93 kW charging power.

Figure 1 presents the connection of 1 E-Trike during three separate hours in the evening versus a 25 kVA distribution transformer. In here, the assumption is the E-Trike driver uses the vehicle from 8am to 5pm, then comes home to his family and charges his vehicle on those random hours. If 1 E-Trike is being connected with the base residential load curve, the 25 kVA distribution transformer will have no overloading.

Figure 1

Figure 2

Figure 2 shows the plots of several number of E-Trike being charged on separate hours of the day. For this case, the assumption is the E-Trike operator/businessman who has several vehicles takes advantage his vehicle charging according to the Time of Use (TOU) rates of the distribution utility. He may utilize a timer-switch to program when the charging begins and ends.  A 25 kVA distribution transformer will overload for the assumed hours for both during evening and during morning except for 3 E-Trikes during morning. A distribution utility coordination with this E-Trike operator will identify that an upgrade from 25 kVA to 37.5 kVA transformer will provide mitigation of the overload unless other households in the service area will shut down all their appliances ( voluntary load shedding).

References:

[1] Consultants sought for $500-M e-Trike project. Available: 

http://business.inquirer.net/74917/consultants-sought-for-500-m-e-trike-project [2] Philippine Electric Vehicle Project. Available: http://cdm.unfccc.int/filestorage/3/K/Y/3KY4J2IW70AZPTX9MS6VGU1QORNE8F/Etrike%20CPA-DD%20ver1.pdf?t=MGF8bWVremlifDCLzXH3EtuSp9elyiR5MR_6

Revision on Loading Impacts of PHUV – E-Jeepney

Ms. Diana Limjoco, manufacturer of E-vehicles in the Philippines responded to my query and corrected my post on charging time of one E-Jeepney which I assumed to be 8 hours. According to her, an E-Jeepney can be charged fully at about 4-5 hours if done right.

Below, I updated the graphs for the loading impact of E-Jeepney(s) charging from 8 hours to 5 hours. No matter what the charging time is, a 25 kVA distribution transformer will suffer overloading for 1 PHUV scenario when charged during the evening and will be heavily loaded in other scenarios. If 2 PHUVs are charged at the same time, the 25 kVA distribution transformer will have severe overloads. And even if the transformer is rated 37.5 kVA, 2 PHUV charging at the same time will overload the transformer when combined with the base residential load.

In this case, the distribution utility has to be proactive in their operations planning in upgrading their distribution transformers or coordinate with consumers who have E-Jeepneys so as to prevent overloading of electrical equipment especially distribution transformers.

Loading Impacts of PHUV Electric Jeepney

It is interesting that while the US is looking into the impact of PHEVs on the existing electric grid infrastructure, the Philippines is producing it's own electric vehicles.

http://electric-vehicles-philippines.blogspot.com is a website detailing most of these products. From E-Jeepneys, electric motorcycles and electric tricycles or electric taxicles, they have it all.

Figure 1. PHUV Electric Jeepney (from http://electric-vehicles-philippines.blogspot.com/2010/04/phuv-electric-jeepney.html)

Though IEEE literature have investigated the impact of PHEVS on distribution transformer loading [1-3], Philippine electric vehicles are very different from the studied PHEVs. No literature have studied the local and global effects of these electric vehicles on the Philippine electric power systems.

In this post, loading impact of charging a PHUV Electric Jeepney on a given distribution transformer. Normally, a distribution transformer serves about five to seven households. A typical load curve is provided in Figure 1, taken from reference 4. The load curve is given in MW and was scaled down to kW. The figure also includes capacities of a 25 kVA and a 37.5 kVA distribution transformers. In the figure, neither of the transformer is overloaded.

Figure 2. Typical residential load curve.

From [5], the PHUV Electric Jeepney charging process is provided:

"PHUV batteries amp hour capacity rating is 220 amp hrs. Since they have a 72 volt system, they have 12 pcs of 6 volt deep cycle batteries. That's 16000 watt hours or 16 kilowatt hours at P8 per kwhour (Meralco rate with all the side charges) is equal to P128 or $2.8 per 8 hour full charge. So if it runs for 65 kms then that's 1.97 per km or 5 US cents per km."

To check the calculation, P = V x I ( P = 72 x 220 = 15,840 watts) . Converting it to kW, P = 15.84 kW which is fully charged for 8 hours. Note that 15.84 kW is above half of a 25 kVA transformer capacity and about 42% loading a 37.5 kVA transformer.

Assuming that the PHUV is utilized for public transport from 8am to 5pm, to integrate the PHUV into the load curve above, three scenarios are studied: (1) charge the PHUV from 6 pm to 2 am, (2) charge the PHUV from 1 am to 8 am, and (3) charge the PHUV from 11 pm to 7 am.

Figure 3 shows the load curve with an additional one (1) PHUV charging considering the three charging scenarios cited above. From the figure, a 25 kVA transformer will overload for charging scenario (1) and will be heavily loaded for the other scenarios.

Figure 3. Residential load curve with 1 PHUV charging.

Figure 4 shows the load curve with an additional two (2) PHUV charging considering the three charging scenarios cited above. From the figure, a 25 kVA transformer will be heavily overloaded for all charging scenarios and even the 37.5 kVA distribution transformer will overload for all charging scenarios.

Figure 4. Residential load curve with 2 PHUV charging.

Electric vehicles are good for the environment and will provide a boost in the Philippine economy since they are locally made. However, it is imperative to look into the loading impact of electric vehicles since they will provide distribution transformer overloading if not investigated.

Further analysis will include additional charging scenarios of electric motorcycles and electric tricycles in the mix. Also, a global outlook analysis is needed if the Philippine power grid as a whole can handle the forecasted usage of electric vehicles in the country.

References:

1. Shao, Shengnan; Zhang, Tianshu; Pipattanasomporn, Manisa; Rahman, Saifur; , "Impact of TOU rates on distribution load shapes in a smart grid with PHEV penetration," Transmission and Distribution Conference and Exposition, 2010 IEEE PES, 19-22 April 2010
2.  S. Shao, M. Pipattanasomporn and S. Rahman, "Demand Response as a Load Shaping Tool in an Intelligent Grid with Electric Vehicles”, IEEE Transactions on Smart Grid, vol. 2, No. 4, December 2011, pp. 624-631. 
3.  S. Shao, M. Pipattanasomporn, and S. Rahman,"Challenges of PHEV Penetration to the Residential Distribution Network,"  IEEE/PES 2009 General Meeting, Power & Energy Society General Meeting, 2009. PES '09. IEEE, Calgary, AB, Canada,  July, 27th, 2009.
4. Occidental Mindoro Electric Cooperative, Inc. Information Memorandum. Available: http://www.omeco.com.ph/files/pdf/OMECO%20INFORMATION%20MEMORANDUM.pdf
5. PHUV Electric Jeepney - http://electric-vehicles-philippines.blogspot.com/2010/04/phuv-electric-jeepney.html

Cost Allocation of SPS Service Using Cooperative Game Theory

Power systems planning and operations are usually defined by N-1 criterion. This means that in an event of a single contingency, no remaining connected transmission elements will be thermally overloaded, no bus voltage will be outside of acceptable limits, no system interface limit is violated, and system stability is maintained.

Special Protection Systems or SPS are widely utilized for increasing power transfer in transmission systems at the same time respecting security constraints [1]. SPS applications usually are generation rejection schemes (GRS), line/transformer transfer tripping and load shedding. GRS are designed to mitigate overloading of a transmission line or lines after an N-1 contingency near the vicinity of a generating plant or are employed to arrest increasing dynamic oscillation which may lead to unstable system conditions. Without the GRS, generation output is curtailed to satisfy the N-1 security criterion. With the GRS, the output of the generation is increased thereby increasing power transfer. Further, GRS also mitigates or delays the possibility of transmission expansion or investment due to transmission capacity constraints.

In a locational marginal pricing based electricity market, curtailment of generation (without GRS), specifically of a cheap generation due to the security N-1 criterion can be considered as transmission congestion. Transmission capacity limitations impede the generation output thereby decreasing the profit opportunity of the generation company (GenCo).  If a GRS is installed for this GenCo, the output of the GenCo is increased and thus there is a clear benefit for the GenCo in terms of profit. When transfer capability is limited, without GRS, the profit of a transmission owner (TO) is decreased due to less power wheeling charges. With the GRS, wheeling charges increase as a consequence of the added power transfer. This premise is the same with the electricity system and market administrator, called independent system operator (ISO), since the ISO charges for cost-based services including scheduling, system control and dispatch.  For the demand side, when generation output is curtailed due to congestion, without GRS, the resulting nodal prices at the demand’s location maybe higher than when a GRS is in place to increase generation output from a cheap generation.

GRS installations have embedded cost and actual service cost [3]. Since electricity market participants have various benefits in having a GRS installation, the cost of the SPS/GRS service must be allocated among the participants. Cooperative game theory [4-5] can be utilized in allocating fair cost on the beneficiaries of the SPS service.

The PJM 5 bus test system [6], shown Figure 1, is to be utilized as an example for the application of cooperative game theory in sharing the SPS service cost among power system organizations.

Figure 1. PJM 5 bus test system.

References:

[1]     W. Fu, S. Zhao, J. D. McCalley, V. Vittal, N. Abi-Samra, “Risk Assessment for Special Protection Systems,” IEEE Transactions on Power Systems, vol. 17, no. 1, pp. 63-72. February 2002. Available: home.eng.iastate.edu/~JDM/WebJournalPapers/RiskAssessentSPS.pdf

[2]     Ancillary Services Presentation. Available: http://www.nyiso.com/public/webdocs/services/market_training/workshops_courses/nymoc/Ancillary_Services.pdf

[3]     J. K. Earle, “Functional unbundling of special protection systems as a required interconnected operating service in a deregulated environment,” MSEE Thesis, University of New Brunswick, 1997. Available: dspace.hil.unb.ca:8080/handle/1882/42522

[4]     H. Singh, “Introduction to Game Theory and Its Application in Electric Power Markets,” IEEE Computer Applications in Power, IEEE Computer Application in Power, vol.12, no.2, pp. 18-20, 22, Oct.1999.

[5]     J. Mepokee, D. Enke, B. Chowdhury, “Cost allocation for transmission investment using agent-based game theory,” International Conference on Probabilistic Methods Applied to Power Systems, Iowa State University, Ames, Iowa, September 12-16, 2004.

[6]     L. Fangxing, B. Rui, "Small Test Systems for Power System Economic Studies," Proceedings of the 2010 IEEE PES General Meeting, Minneapolis, MN, July 25-29, 2010.

Leyte Mindanao Interconnection Project

When the Leyte Luzon HVDC project was conceived, part of the plan was to extend the interconnection to Mindanao. From ABB, the figure below presents the interconnection projects.

The National Grid Corp. of the Philippines (NGCP) is now seeking approval for the LMIP, as reported by the Inquirer.

The Leyte Luzon link is a Current Sourced Converter (CSC) HVDC. This is the reason why reactive compensation is needed in its operation to support real power transfer and limitation of harmonics. When transmission lines are toppled in the Bicol region due to typhoons, the MW dispatch of the HVDC was curtailed due to the low short circuit capacity (SCC) in the area. Low SCC may result to commutation failure in the valves when voltage is weak on the AC system. This link also requires to operate between a minimum and a maximum MW bandwidth.

With the LMIP, I am guessing the technology of Voltage Sourced Converters (VSC) HVDC will be used. The side of Mindanao has been suffering with generation deficit thus will have low SCC and less reactive power support. VSC HVDC can be used in such case. Reactive power compensation is not required in VSC HVDC to transfer real power since it can operate independent of real and reactive power. Also, at high switching frequency for the VSC HVDC, less filtering or switchable harmonic filters are not needed. With this, if LMIP uses VSC HVDC, it can be utilized to start-up the Mindanao grid after a major outage or blackout since it can operate at low SCC or weak AC system. Another advantage is VSC HVDC can operate between 0% and 100% of rated active power in controllable in both directions without the need of DC voltage reversal since both Mindanao and Visayas need generation capacity to satisfy growth demand.

The Philippine power grids are one of the most advanced power systems in the South East Asian region having CSC HVDC, wind power and solar power integrated into the electric system. With the proposal of LMIP, new technology like VSC HVDC may find a way to connect and power the islands.

Administrative Losses

The figure below presents the administrative loss percent of each electric cooperative considering the number of employees for each cooperative.

In this post, I consider the administrative loss to be proportional to the number of employees.

In this terms, the more employees, the more electricity usage within their facilities. So less usage means less employees working for the cooperative. The efficient electric cooperative would have less administrative loss given more employees.

With this premise, Tarlac I looks like an efficient operated cooperative since it has more employees yet they incur less power losses for their facilities. On the other hand, Davao Sur has less employees but has spent more administrative losses.

Philippine Electric Cooperatives' System Loss

The following figure presents the system loss in percent of all electric cooperatives in the Philippines. Data came from the NEA website.

 

The average system loss throughout the five year period is about 15%. The median system loss is around 14%. This is not bad for the NEA, though some cooperative suffer with significant power losses in their distribution system as seen from the figure above.  It is notable that high system loss are found in Mindanao, Central Luzon, Bicol and parts of Visayas.

Energy Efficiency Impact on Demand

Recent news on the DOE secretary was about his speech at an energy forum attended by electric power industry stakeholders. The secretary was quoted to point at energy efficiency as a solution to the crisis in energy. He said if people would practice the Energy Efficiency Protocol,  the expected demand reduction will be 20% for residential load and 25% for industrial/commercial demand. If residential load is say 30% of the total grid demand then we can follow a formula like,

            TD_Eff = Res(0.8) + Ind(0.75) = (0.3)TD(0.8) + (0.7)TD(0.75) 

TD is the total demand and TD_Eff is the TD with energy efficiency at the demand side.

The DOE secretary also mentioned the energy savings from using energy efficient devices will solve the power shortage for three to four years. Following the DOE forecast on Visayas and applying the formula above, I wanted to verify the declaration.

Looking at the graph above, the DOE demand forecast is above the dependable generation capacity. When energy efficiency is accounted, the demand goes below the dependable capacity for the upcoming four years.

Does this solve the power shortage? No.

Grid operations require generation reserves to maintain system frequency and prepare for unforeseen grid contingencies. In real time, there are generation or transmission outages due to planned maintenance or forced outages.Visayas grid, as per NGCP website requires about 190MW for its generation reserves at the present time. Apparently, load will catch up with the generation capacity in 2013 based on DOE's projections.

Energy efficiency is good not only for the reduction of grid demand but also it makes the grid environment friendly. It will surely help, but given the situation, it does not solve the power shortage for the coming four years.

PS - At present, the dependable capacity in the Visayas alone is at 1,505 MW while peak demand is at 1,430 MW, with a required reserve margin of 335 MW.

Demand-Side Management in Visayas: Why Another Route?

Wholesale Electricity Spot Market (WESM) proposed Visayas Supply Augmentation Auction (VSAA) Program which was approved by the Energy Regulatory Commission (ERC). The VSAA is aimed for demand-side management (DSM) in Visayas where interruptible load of embedded generators will be auctioned just like a competitive market. Please see approved proposed VSAA.

There have been reports that Visayan Electric Co. (Veco) has been practicing (DSM) by having interruptible contracts to its consumers. See this link: Veco, firms to sign power deal.

My question is this: Veco has a working DSM model system. Was there a study providing benefits of a market based DSM compared to the existing practice? Is there a need for a market based DSM that would add another fraction of peso to the rates being charged?

With ERC's approval, market based DSM will go through WESM instead of having Veco and its consumers taking directly. There might be added cost to that. You can say this is only Veco, how about the other distribution utilities? Well, the Veco model works as reported, why not adapt the model that works fine.

Why another route?

Demand Side Management in Visayas: Making It Work

As Visayas is having power problems, demand side management brings new opportunities to alleviate need for investments in new generation.

Inquirer reports...Ten major commercial establishments in Cebu let go of at least 174,847 kilowatt hours (kwH) of power from the local power grid over the past two weeks, allowing more electricity to be used by residences.

The “deloading” from the power grid was made by firms which relied on their own backup generators during periods of peak demand for electricity in Cebu.

See link for full report: Firms start power deload

Solving Non-Technical Losses Problem by Technical Methods

Non-technical losses in distribution systems comprised about 2-3%, my estimate, of the total system losses. Total distribution system losses equals technical losses plus non-technical losses.

In my experience and some readings, I believe that non-technical losses can be minimized or mitigated by utilizing non-technical strategies.

1. Modeling and benchmarking technical losses thru computer simulations - if a DU can measure the technical losses incurred in operating its distribution system with the variation of supply and demand using a computer program, then the DU is in a position to quantify and identify probable nodes of sources of non-technical losses in the system comparing power/energy output from electricity meters. This approach may take some technical challenges, especially with the database development, but if accomplished the DU will have in its hands a tool that can predict energy efficiency of its distribution system franchise.
2. Installation of totalizing meters - the measurement of energy output from a certain distribution feeder and laterals thru totalizing meters can be an effective way to guard pilferage along the feeder or lateral. Some DUs even install totalizing meters after the distribution transformer feeding a secondary feeder. The accuracy of these totalizing meters must be accounted when investigating or assessing energy input and output among electricity consumers.
3. Statistical analysis of electricity meter readings - ample data from electricity meters can be analyzed statistically over time to estimate significant deviation from usual meter readings. This will help the DU to keep track the energy usage of its consumers and will have a benchmark in case significant meter reading deviation especially at the totalizing meters is observed. Statistical monitoring of energy consumption per sector, per class and geographical set-up must be employed and statistical evaluation of meter readings will be in vain if electricity meters are not up to the standard accuracy. Energy consumption bands must result from the statistical evaluation to confirm anomalous meter readings. Upgrading of electricity meters to meet standard accuracy must be conducted to support reduction of non-technical losses thru statistical analysis.
4. Technical training of DU personnel must be given plus enhancing employees’ loyalty and political will to eliminate pilferage in the distribution system must be considered. DU personnel who play an important role in mitigating non-technical losses must have deep loyalty to the company and must have ample technical knowledge in combating electricity pilferage.

Power Quality Problems Always Exist

The Philippine Distribution Code (PDC) has Power Quality (PQ) performance regulation for Distribution Utilities. In Section 3.2 of the PDC, it provides generalities and specific limitations for quality regulation. I have copied section 3.2.1.2 from the PDC for the purpose of this article, see below.

In this section, the PDC points to the identification of a PQ problem in the distribution system by classifying presence of quality parameters. Going beyond this section are specified limits of the parameters stated above which clearly identifies the existence of a PQ problem. It is interesting that this PDC section identifies PQ problems where some of the classifications always exist in operating a distribution system. My rationale are the following:

• Power system frequency is seldom at its nominal value of 60 Hz. The continuous variation of loads impact the maintenance of frequency at 60 HZ. Item (a) of the said section implies that a PQ problem due to frequency deviation always exists.
• Harmonic frequencies always exist in distribution systems. The issue if these harmonics are acceptable or not is another facet. But voltage harmonics and current harmonics are always present in a power system due to the popular usage of electronic-based devices and equipment. Item (c) of the said section above implies that a PQ problem exist due to the presence of harmonic frequencies, whether tolerable or not.
• Items (c) and (d) of the said section are combined definitions for voltage unbalance. In a practical distribution system, voltage unbalance exist at all nodes due to the two-phase and single-phase laterals in the three-phase distribution feeder and unequal loading of the three-phase distribution lines. If this unbalance in voltage is acceptable of not is about the magnitude of the unbalance. If we follow the thesis of the said items, then a PQ problem exist even at acceptable levels of voltage unbalance.

The PDC definition for the existence of a PQ problem, with respect with the section above, gives us an understanding that a PQ problem exist not withstanding the magnitude of frequency deviations, harmonic frequencies and voltage unbalance magnitudes.

Simple Method for Selecting Overhead Distribution Line Conductor

Distribution Utilities (DUs) when planning for their distribution system, are faced with various options and constraints. One of the DUs’ process in system planning is choosing the right size of overhead distribution conductor for a given load, voltage level and expected load growth just to name a few. Most of the time, DUs have a set of standard sizes of conductors in the stock shop ready to be utilized for meeting additional demand or has a set of policies what size of conductor to be used for level of voltage or type of load. These practices do not follow that given the new conductor installation, DUs comply with various performance regulation.

In the performance regulation of DUs, it is important to meet the following:

• Supply the voltage within allowable limits - normally this is between 0.90 to 1.10 per-unit voltage.
• Minimize losses - to select a conductor is to ensure that as the power is being delivered, lesser line losses are produced.
• Minimize cost of conductor - economic regulation addressed in planning that DUs as much as possible to lower cost and at the same time operate within performance criteria.

In addition, the DUs must maximize power delivered, i.e. - the DU sees to it that the demand will be supplied with the power it needs given any time. Maximizing power transfer enables maximum utilization of the asset.

In this blog, consider a load of 200 amperes at 13.8kV level and selection between conductors ACSR sizes of 1/0 to 4/0 is to be determined for a line length of 1000 meters. The cost of conductors are derived from National Electrification Administration (NEA) website. The variations of voltage versus losses, cost of conductors versus losses and power delivered versus losses are plotted below. The conflicting patterns of voltage, cost of conductors and power delivered versus line losses are evident from the figures. The size of the conductor to be selected must be near the intersection point which minimizes the parameters involved. In this example the appropriate conductor size, the nearest conductor size to the intersection of the curves must be chosen, is ACSR 3/0.

Benefits of System Loss Reduction

Aside from impacting or not impacting electricity rates, system loss reduction has the following benefits:

• Reduction of fuel emissions due to lesser use of fossil-fuel generating plants - this has societal impact as it cover environmental concerns.
• Utility system capacity savings - decrease in losses provides released extra capacity for the distribution lines and transformers.
• Promotion of Energy Efficiency - it will be noted that the Distribution Utility (DU) is an energy-efficient electric company as it tries to decrease its system loss.
• Improvement of system voltage profile - the utility is regulated to supplying a range of voltage level and reduction of losses will produce a marginal system voltage quality that may be acceptable. This will also provide good power quality at the convenience outlets of consumers allowing their electric equipment/appliances to operate without mis-operation or loss of life.
• Increase Utility Commercial Appeal - a DU aiming at system loss reduction gets an added commercial appeal in the restructured power industry. This is important in the changing environment of the power industry, have you seen MERALCO TV commercials?

There is an optimum level of system loss reduction unique for all Distribution Utilities (DUs) where further reduction of losses will not result to further reduction of operation cost but more investment expenses. On the other hand, as demand rises in a distribution service franchise, technical losses and non-technical losses (utility own use) will at some point come with the demand increase. The equation of generation equals losses plus demand holds true. This is revealed by Philippine Power Statistics as shown in the figures below (the values include transmission and distribution losses, but this does not negate the point) :

Finding ways to reducing system loss must be a continuing program since it always provide benefits to the DUs and electric consumers.

Getting Lost with System Loss

The Energy Regulatory Commission (ERC) is calling for comments from various stakeholders on a new resolution they are proposing on reduction of distribution system losses incurred by Distribution utilities (DUs) which are Private Utilities (PUs) and Electric Cooperatives (ECs) in their operation of their service areas. Figure below is an extraction from the ERC document on the resolution.

From the illustration, the regulated system loss caps have been long withstanding for about eight years. The 9.5% and 14% loss caps for PUs and ECs respectively, are about to celebrate their ninth birthday until this new resolution on system loss caps reduction which is aimed to be implemented in January 2009 billing. The proposed 8% cap on the PUs might be tight since presently MERALCO operates its vast distribution system following a 9.5% loss policy. There are other PUs but benchmarking with MERALCO is a sure test if the other PUs can comply with the proposed 8% cap. The proposed 11% system loss cap on ECs is a product of National Electrification Administration (NEA) media declaration on system loss saying that by 2009 the national average for system loss for ECs will be 11%. The 2006 NEA scorecard does not report this 11% but points that about 53 out of a total of 84 ( I thought there are total of 98 ECs) ECs comply perfectly with system loss reduction.

Reduction of system loss caps always provide good benefits for both consumers and the electric distributor, there is no doubt on this and the currently applied caps should have been in Grade 3 in the present school year. But giving pressure to the DUs to comply within five months can be challenging. Given the facts for both PUs and ECs, the proposed resolution will be an expected regulatory debate in the ERC hearings. Aside from decreasing system loss, DUs look into improving system reliability and quality of supply in their planning and operations which I believe are of equal weight with system loss. If this resolution is implemented, DUs might get lost with reducing their system loss.

Philippine Electric Cooperative Analysis : Distribution, Supply and Metering (DSM) and Annual MWh Sales

Economics tells us that having more sales tend to bring down the prices. The components of electric distribution tariff consists of different items. Distribution, Supply and Metering (DSM) Charges are among basic fees that are collected from residential consumers. Figure below from the Energy Regulatory Commission (ERC), illustrates the components of the total residential distribution tariff.

In this blog, we show that increasing the electric energy sales tend to reduce the DSM charges of the Electric Cooperatives (EC). The next figure is derived from the EC data and is analyzed thereof. It is shown that the more energy sales produced by an EC, the lesser DSM fees the consumers pay. This is due to the fact that the path of electric power flow to more consumers is being utilized efficiently. More consumers means more power to be distributed, supplied and metered using the same electric distribution circuits. EC #95 having more sales charges the lowest DSM fee while EC #3 charges the highest DSM fee having the lowest energy sales. It is interesting that EC #94 charges low DSM fees while providing not so much high energy sales. This may be due to the distribution system configuration of the said EC where is utilized efficiently.

Philippine Electric Cooperative Analysis : Circuit Kilometer and Annual MWh Sales

In operating and planning electric distribution business, the expansion and demand growth must be intertwined. Expansion won’t happen if not demand driven. Increasing demand must be met by system expansion. The figure below is a graphical illustration of Philippine Electric Cooperatives (PECs) in year 2006, depicting their distribution line in circuit kilometers versus the annual sales in MWh.

From the figure, EC #91 has the longest ckm but does not have the highest sales. EC #96 has the highest energy sales with operating significant lesser ckm of distribution line compared to EC #96. It can by thought that EC #96 might have a service area that is very rural thus it has to erect longer lines to reach consumers. On the other hand, if this is not the case, then EC #96’s investment in distribution lines is not optimized since it has put a longer ckm with a smaller demand.

The regulation of system expansion must meet the rise of demand up to the point that it satisfies reliability and quality performance. However, investment in distribution business must not be overdone because some of these costs are passed on to the consumers.