Mitsubishi Heavy Industries Technical Review Vol. 55 No. 4 (December 2018)
1VPP: New Stage in Energy Management
Smart Utilization of Self-Generation Facilities withAutomated DR System

TOSHIAKI TANABE*1SATOSHI KOKAJI*2

OSAMU NAKAKITA*3

MANABU INOUE*4Along with the expansion of renewable energy, balancing capability for stabilizing theelectricity system is required. For the utilization of consumers' self-generation facilities as thisbalancing capability, verification experiments and commercial transactions of demand response(DR)*1 have been actively carried out. Furthermore, in future domestic electricity system reform,
self-generation facilities are expected to be important elements in establishing VPP (Virtual PowerPlant)*2. Therefore, Mitsubishi Heavy Industries, Ltd. (MHI) has been promoting effective use of
self-generation facilities targeting consumers to optimize energy supply and demand, and wedeveloped an automated DR system so that they can be utilized as electric power for supply anddemand balancing in cooperation with the electricity market. This paper presents technical results
thereof.
*1: Suppression of power receiving of consumers upon request from Transmission System Department throughcontrol of electricity demand and output of their self-generation facilities.
*2: Integrated control of distributed energy resources to use them as a single power plant.

|1. Introduction
As part of domestic electricity system reform, electric power retailing was fully liberalized in2016. Power transmission and distribution business operators started public offering of electric
power for balancing supply and demand in 2017, and various verification experiments and tradingof negawatt power are becoming active among power transmission and distribution business
operators (manage and operate electricity system), aggregators (collect electric power suppressedby consumers), and consumers. The transmission and distribution department is planned to belegally separated in 2020, and the effective utilization of consumers' self-generation facilities in thefuture is expected.
Furthermore, the Japanese cabinet decision for the basic policy on the expansion ofrenewable energy and the decentralization of balancing capability supply and system functions in
the future was made in the 5th Strategic Energy Plan.(1) In this plan, it is expected that as renewableenergy rapidly spreads, the market value of kWh (energy quantity) will decrease, on the other hand,
the market value of ⊿ kW (balancing capability) for stabilizing unstable electrical network will
increase, so the future supply-demand balancing market will grow.(2) Therefore, the importance ofutilizing consumers' self-generation facilities will further increase.
In addition, there is increasing demand from consumers who want to make more effective
use of their self-generation facilities with a low capacity utilization rate or large redundant powergeneration capacity.
Under such circumstances, as one of the menu items of the ENERGY CLOUDTM Service*1

Power & Energy Solution Business Planning Department, Power & Energy Solution Business Division, Power Systems*2Program Execution Manager, Power & Energy Solution Business Planning Department, Power & Energy Solution Business*3Deputy Director, Engine Technology Development Department, Engine & Energy Division, Mitsubishi Heavy Industries Engine &*4Senior Manager, Power & Energy Solution Business Department, Power & Energy Solution Business Division, Power SystemsDivision, Power Systems
Turbocharger, Ltd,

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targeting the improvement of the business value of consumers, MHI supports the operation ofself-generation facilities for the optimization of the energy supply and demand of consumers, andhave developed an automatic DR system in response to the above market trends and consumer
needs.

|2. Outline of DR system
2.1

Background of DR utilization in balancing of domestic power supply anddemand

DR is used to suppress the amount of electric power that consumers receive from electrical
network by power transmission and distribution business operators requesting that consumersconserve electricity for a certain period of time or operate their self-generation facilities, etc.,
during a time period when power supply and demand becomes tight. Tightness of domestic
electricity supply and demand may occur during summer days when the cooling demand is high, on
winter mornings and nights when the heating demand is high or in the evening when the output ofphotovoltaic power generation suddenly drops.
Under the current system, power transmission and distribution business operators are
responsible for constantly conforming to the supply and demand of electric power on the basis of
the principle of balancing them at a certain point of time, plan the supply amount according to theamount of demand and invest in power generation facilities. However, it is predicted that if
electricity procurement from the supply-demand balancing capability market is institutionalized in
the future, DR implemented by effectively utilizing consumers’ self-generation facilities is more
economical than introducing new facilities or restarting existing facilities not in operation to deal
with the peak demand of electric power, so it is expected that the utilization of DR will increase.
For consumers with self-generation facilities, it is important to examine the implementationof DR with an understanding of the following items, which are described later.
(1) DR transaction flow(2) DR success/failure evaluation method

2.2

DR transaction flow
Figure 1 shows the DR transaction flow. An overview of DR is described below.

Figure 1

DR trading flow

(1) When power supply and demand is tight, the power transmission and distribution business
operator makes a DR request to the aggregator.
(2) The aggregator issues a DR request to consumers.
DR requests include information such as DR start time, DR duration time, target receiving
power, etc.
(3) The consumers that received the DR request suppress the amount of electric power indicatedand carry out DR by operating their self-generation facilities.
Specifically, they collect information on the receiving power of the factory, the operating
conditions of each engine, etc., determine the engine to be activated and the power
generation output, and issue command signals to each engine.

Mitsubishi Heavy Industries Technical Review Vol. 55 No. 4 (December 2018)
3(4) The aggregator collects the receiving power suppression amount of each consumer andreports the DR implementation results to the power transmission and distribution business
operator.
In the case of the automated DR system presented in this paper, procedures (2) and (3) are
performed automatically.

2.3

DR success/failure evaluation method

Figure 2 presents the DR success/failure basis concept and Figure 3 gives a summary ofbalancing on the day. The power value that is a criterion for suppressing power reception is called
the baseline and is calculated as follows based on the High 4 of 5 method*3 described in theGuidelines for Trading Negawatts(3) issued by the Agency for Natural Resources and Energy.
(1) Calculate the average value of the difference between the actual receiving power from 5hours before to 2 hours before the DR execution time and the baseline (without balancing onthe day) obtained by the High 4 of 5 type calculation.
(2) Add the value calculated in (1) to the baseline (without balancing on the day) after the startof DR, and set this value as the final baseline (with balancing on the day).
The value obtained by subtracting the contract power suppression from the baseline (withbalancing on the day) is the target receiving power.
The value obtained after subtracting the power obtained from multiplying the contract power
suppression by the coefficient determined in the contract with the aggregator from the baseline(with adjustment on the day) is the criterion for the success/failure determination. If thissuccess/failure criterion is satisfied, DR is successful.
In the case of the automated DR system described in this paper, the actual receiving power iscontrolled so as to follow the target receiving power.
*3: A method using demand data of 4 days with a high average demand amount out of the last 5 days.

Figure 2 DR success/failure basis concept

Figure 3

Summary of balancing on the day|3. Developed automated DR system
3.1

Characteristics of automated DR system

Figure 4 depicts the configuration of the automated DR system, and Figure 5 is aphotograph of its external view. The automated DR system adopts DIASYS NetmationTM, which isa plant control system produced by Mitsubishi Hitachi Power Systems, Ltd. and has abundant sales
results and high reliability in more than 2,000 projects.
For consumers with self-generation facilities to make DR contracts with aggregators andMitsubishi Heavy Industries Technical Review Vol. 55 No. 4 (December 2018)4

maximize revenue, the following items are important. The characteristics and verification
experiment results thereof are described later.
(1) Automated control with high followability(2) Short DR reaction time(3) Reverse power flow prevention function during DR

Figure 4 Configuration of automated DRsystem

Figure 5

Photograph of external view

3.1.1 Automated control with high followability
For automated control of the DR system, the output control expertise on engine
generators that Mitsubishi Heavy Industries Engine and Turbocharger, Ltd. (hereinafterMHIET), which manufactures and sells engine generators, has accumulated over the years isutilized.
When evaluating DR implementation results, the amount of electricity exceeding thecontract power suppression is out of the scope of the compensation, so it is desirable to deal
with DR at the minimum energy cost. For this reason, we realized automated control thatalways follows the receiving power with fluctuation and can achieve the standard with lessexcess and fewer deficiencies. Figure 6 illustrates an image of automated control with highfollowability.

Figure 6

Image of automated control with high followability

3.1.2 Short DR reaction time
The time from a DR request to DR start is called the DR reaction time. The shorter thecontracted reaction time, the higher the reward at the time of DR success. Therefore, weimplemented output control in consideration of the output characteristics, startup time, etc., ofthe engine generator, and realized a shortened contracted reaction time. Figure 7 shows animage of a short DR reaction time.

Mitsubishi Heavy Industries Technical Review Vol. 55 No. 4 (December 2018)
5Figure 7

Image of short DR reaction time

3.1.3 Reverse power flow prevention function during DR
In cases where the receiving power suddenly drops due to the suspension of theproduction facility, etc., a large negative balancing on the day is added to the baseline and thecalculated target receiving power may fall below zero. Based on the fact that the current DR istargeted at the negawatt balancing power amount and that some consumers have power
contracts prohibiting reverse power flow, a control function to implement DR within the range
where no reverse power flow occurs is adopted. When the target receiving power becomes 0 orless, reverse power flow prevention is realized by setting the substitute target receiving powerand controlling the receiving power. Figure 8 presents an image of the reverse power flow
prevention function during DR.

Figure 83.2

Image of reverse power flow prevention function during DR

Verification experiment results

The developed automated DR system was installed at our Sagamihara Machinery Works tocarry out a verification experiment using engine generator in the factory.
The main items evaluated by the verification experiment are shown below.
(1) Achievement rate*4 of DR requests(2) Followability of DR control(3) Reverse power flow prevention function during DR
3.2.1 Evaluation results of achievement rate of DR requests
Table 1 and Figure 9 give examples of the evaluation results of the achievement rate ofDR requests issued by the aggregator during the verification experiment. The achievement rate
was good in each time zone and the average receiving power was controlled near the target
receiving power. Thus, an automated DR system that could respond appropriately to DR
requests was realized.
Table 1
Evaluation time*5

Achievement rate

Example of evaluation results of achievement rate of DR requests
0-30 minutes

30-60 minutes

60-90 minutes

90-120 minutes

105%

105%

107%

106%

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6

Figure 9

Example of evaluation results of achievement rate of DR requests

3.2.2 Evaluation results of followability of DR control
Figure 10 presents the power trend graphs before and after the improvement of thefollow-up control, which indicate the evaluation results of the followability of the DR control.
Utilizing MHIET’s expertise, the followability of the receiving power to the target receiving
power was improved by controlling the engine generator output at a cycle of 5 seconds.
In addition, control was carried out so that the receiving power became the target
receiving power at the start of DR in consideration of the output characteristics of the engine
generator.

Figure 10Power trend graphs before and after improvement of follow-up control

3.2.3 Evaluation results of reverse power flow prevention function during DR
It was indicated that even when the target receiving power is 0 or less or there is apossibility that the receiving power may fluctuate below 0 during DR, reverse power flow canbe prevented by setting a substitute target receiving power as the new target value to control thereceiving power. Figure 11 depicts power trend graphs of the cases with and without thereverse power flow prevention function. Since there is no measurement data of the electric
power of reverse power flow, an image thereof is added to the figure.

Mitsubishi Heavy Industries Technical Review Vol. 55 No. 4 (December 2018)
7Figure 11 Power trend graphs of cases with and without reverse power flow preventionfunction

3.3

Development from DR to VPPAlong with the expansion of renewable energy in the future, it is anticipated that the role ofDR will further increase as a balancing capability for electrical system stabilization. On the other
hand, with the future separation of transmission and distribution, the establishment and operation ofVPP that integrates and controls distributed energy resources to use them as a single power plantfor electric power supply to the system is expected. DR is supposed to generate no reverse power
flow by suppressing the electric power received from the system using self-generation facilities,etc. Also in the case of VPP where reverse power flow occurs, it is expected to effectively utilize
self-generation facilities to improve economic efficiency. Therefore, we would like to make use of
the developed DR technology for VPP and contribute to further the effective utilization ofconsumers' self-generation facilities. Figure 12 is a conceptual diagram of VPP.
*4

: Achievement rate = (Baseline - Receiving power) / Contract power suppression × 100 (%): Evaluation of the DR implementation results with the evaluation time unit set to 30 minutes.

*5

Figure 12 Conceptual diagram of VPP|4. Conclusion
We developed an automated DR system that can utilize consumers' self-generation facilities
for supply and demand balancing in the electric power market. Our company aims to optimize
energy demand and supply for consumers as part of the ENERGY CLOUDTM Service. On the otherhand, it is anticipated that the role of DR will further increase as a balancing capability forelectrical system stabilization. Furthermore, self-generation facilities are expected to be an
important element of future VPP. Therefore, we would like to contribute to the further effective useof self-generation facilities by using the developed automated DR system.

Mitsubishi Heavy Industries Technical Review Vol. 55 No. 4 (December 2018)
8TMENERGY CLOUD and all related marks and logos are registered trademarks of Mitsubishi Heavy Industries,
Ltd. in Japan and other countries.
DIASYS NetmationTM and all related marks and logos are registered trademarks of Mitsubishi Hitachi Power
Systems, Ltd. in Japan and other countries.

References(1)(2)

Agency for Natural Resources and Energy，Strategic Energy Plan，(2018)
http://www.meti.go.jp/english/press/2018/0703_002.html
Agency for Natural Resources and Energy, The Guidelines for Trading Negawatts Revised，（2016）
http://www.meti.go.jp/english/press/2016/0901_01.html