［ Energy Management System ］

Wide-Area Internal Energy
Sharing between Yokohama City
University Medical Center andGovernment Office Building inYokohama Minami-Ward
Keywords

Wide-area internal energy sharing, EMS, Integrated control, Electricity market deregulation, Energy delivery over own transmission line, Energy retail wheeling

Abstract

Wide-area internal energy sharing is maintained among internal facilities ofthe Yokohama City University (YCU) Medical Center, the Government Ofﬁce
Building in Yokohama Minami-Ward, and the Minami Civil Engineering Ofﬁce
Workshop. The intent of the program is to improve disaster readiness, environmental conditions, and economic gain by a wide-area efﬁcient use of energy. As
one of the key facilities to support such an energy sharing operation, we supplied a smart Building Energy Management System (smart BEMS). This facility
manages the operation of energy sharing and also makes the integrated control
of Combined Heat and Power (CHP) and receiving power to ﬁt the overall energy
demand and system operation status.
In order to manage energy operation, the BEMS is generally used. In theevent that proper management of energy supply is required, it is necessary tocontrol both the energy consumption side and the power supply side. In such acase, the smart BEMS plays a key role by managing both the energy consumption and supply side and by making effective control.

1 Preface
At the Yokohama City University (YCU) MedicalCenter, the in-house electric power grid system
adopted a redundant system in order to provide
safe and reliable medical services. In addition, aCombined Heat and Power (CHP) was introduced
as a distributed energy resource. This enhances thereliable supply of energy. At the Government Ofﬁce
Building in Yokohama Minami-Ward (“Minami Ofﬁce
Building” hereafter) which recently moved to thevicinity of the YCU Medical Center, the continuity ofenergy supply was needed because a regional
administrative function has to be maintained in theevent of an emergency as the building is an evacuation shelter in the event of a disaster.
Against such a background, wide-area internalenergy sharing is conducted among facilities of theYCU Medical Center, the Minami Ofﬁce Building,and the Minami Civil Engineering Ofﬁce Workshopthat belongs to the Minami-Ward Government Ofﬁce.
This arrangement makes an effective internal use of08

Takashi Uyama

MEIDEN REVIEW Series No.169 2017 No.1

energy in a wide area. In so doing, it aims to improvedisaster readiness, environmental conditions, andeconomic gain.
This paper introduces the outline of the smart
Building Energy Management System (smart BEMS)
that we delivered as one of the major facilities
designed to support optimal management of widearea internal energy sharing.

2 Background
In order to assure the continuity of energy supply at the Minami Ofﬁce Building and other afﬁliatedbuildings, the installation of a CHP in these buildings like that at the YCU Medical Center can be aneffective method. When the heat load was small inbuildings other than the Medical Center, however,
the rate of waste heat utilization was lowered and it
became difﬁcult to maintain high-efﬁciency operation. When the CHP was installed at the YCU
Medical Center, waste heat could be used at thehospital and generated electric power that can be

YCU Medical Center

Data sharing

Smart BEMS
Existing
centralmonitoring
system

Optimal control ofenergy supply

Monitor and control

ElectricalHeat
equipment source
facility

BoilerMinami Government
Office Building, etc.

NewCHP

CentralmonitordeviceMonitor and control

Existing
CHP

PV

Electricalequipment

Heatsource
facility

Gas supplier, etc.

Fig. 1

Outline of Energy Wide-Area Internal Sharing
SystemThe smart BEMS manages and controls the wide-area internalenergy sharing.

Internet

Modem

TV antenna
LCD

LCD
Keyboard

Speaker
RouterCPU
device 1

Mouse

Time
serverCPU
device 2

Printer
Hub

Supervisory
controlconsoleStandard
protocol

Switching HubStandard
protocolFig. 1 shows an outline of the wide-area internal energy sharing system. At the YCU MedicalCenter, a CHP was newly installed in order to meetthe estimated power demand for the power receiving related parties like the Minami Ofﬁce Building. In
this situation, power is fed to these afﬁliated buildings by combining the power of the REP. The recovered waste heat of the CHP is used as a heat source
for the YCU Medical Center.
Operation for overall wide-area internal energy
sharing is managed by the smart BEMS. Data linkage with the central monitor system at the Minami
Ofﬁce Building is also managed by this smart
BEMS. In addition, the smart BEMS takes complete
control between the CHP and power receiving fromthe REP. This control reﬂects on-going energy
demand and operating conditions at the YCU
Medical Center, the Minami Ofﬁce Building.
Fig. 2 shows a system conﬁguration of thesmart BEMS. The smart BEMS is composed of thesupervisory control console installed at the central
monitor room and the remote stations installed atEnergy delivery (over owntransmissionline)

Standard
protocol3 System Outline

REP, etc.

Standard
protocolsimultaneously fed to other afﬁliated buildings. Thisis the best method to maintain high-efﬁciency CHP
operation. In addition to using the power supply
from the CHP, the YCU Medical Center has backup
power received at a super high voltage from anElectric Power Company (EPCO) or Non-EPCO
company (“Collective retail electric provider” or“REP” hereafter). As such, the continuity plan ofenergy supply can be improved at the Minami Ofﬁce
Building.
When a CHP was newly introduced to the YCU
Medical Center, a structure for the internal widearea energy use was established and it improved
the features of disaster readiness, environmental
conditions, and economic gain by setting up the private power transmission line toward the Minami
Ofﬁce Building and the Minami Civil Engineering
Ofﬁce Workshop so that power can be distributed tothese buildings in a speciﬁc power supply mode.
In order to manage the energy operation well,a BEMS is generally used. In the event that proper
energy supply management is required, it is necessary to control not only energy consumption, butalso the power receiving side. In such a case, asmart BEMS plays an important role as it can properly control the energy.

Hub
Existing
CHPFig. 2NewCHP

Existing
centralmonitorsystemCentral monitor
system (Minami
Government
Office)Remotestation

System Configuration of the Smart BEMS

Data are gathered at the CPU unit in the supervisory control console and the smart BEMS manages and controls.

each site. This equipment acquires meteorologicalinformation via the Internet and makes time calibration by receiving the time data from land-based digital TV broadcasting. Data exchanges with external
facilities are outlined below.
( 1) Existing CHP
Based on communication between the smart
BEMS and the existing CHP, it makes the required
data retrieval and builds a control line from thesmart BEMS to the CHP. It adopted standard communication protocol commonly used for control data
MEIDEN REVIEW Series No.169 2017 No.109

exchange among FA controllers.
( 2 ) A newly-installed CHP
In the same manner as for an existing CHP,
necessary data exchange between the smart BEMS
and a newly-installed CHP is carried out in accordance with the standard protocol.
( 3 ) Existing central monitoring system
Communication is maintained between thesmart BEMS and the existing central monitoring
system in order to retrieve necessary data. For thispurpose, a standard protocol applicable to building
automation was adopted.
( 4 ) Central monitoring system (for Minami Government Ofﬁce)
Similar to the existing central monitoring system, necessary data are exchanged between thesmart BEMS and the central monitoring systeminstalled at the Minami Ofﬁce Building using thestandard protocol.
Different energy administration screens canshow the detailed CHP status display, status displayof power receiving and distribution facilities at theYCU Medical Center and the Minami Government
Ofﬁce, and overall energy ﬂow status display. Basedon these status display screens, the operator canobtain a general overview at-a-glance.

 Equipment start-up times restriction
 Equipment default stop time Equipment control compensation
setting
 Equipment operation amountsetting

Meteorological forecast

Design data

Parameter check ②

 Equipment configuration
 Equipment characteristics

SmartBEMS

 Demand pattern prediction
 Gas turbine intake air temperature
characteristic adjustment
 Calendar information

Fig. 3

The total control of the CHP and receiving
power by the smart BEMS is realized by the optimal
control of energy supply supported by the functionof this system. The effectiveness of this function
was already veriﬁed through the demonstrative
operations for the facilities of Yokohama WorldPorters, which is part of the Yokohama Smart City
Project (YSCP). The delivery of this smart BEMS is,
therefore, the ﬁrst such achievement of practicalapplication. Activities of wide-area internal sharing
among the YCU Medical Center, the Minami Ofﬁce
Building, and the Minami Civil Engineering Workshop
can be deemed as a follow-up development based
on YSCP demonstrative test results.
Fig. 3 shows a ﬂowchart to realize optimal control of energy supply. Based on the operational concept, design data, and actual data, we determined
the technical set-up conditions in advance. In addition to these conditions, we combined with meteorological forecasts, calendar information, and various
operational data to realize optimal control.

Annual simulation

 Contents of external energy
purchase contract with REP
 Energy unit price Maintenance cost
 Upper limits of running equipment

Input values

Control
New CHP

Practical data

Existing CHP Designation of specific dates
 Fuel cost / adjusted unit price ofraw materials
 Specifies the priority of runningequipment

Preliminary study phase

Parameter check ①

4.1 From Experimental Stage to Practical Use

Actual operation phase

Operational concept

4 Smart BEMS

Flowchart to Realize Optimal Control of Energy Supply

Condition setting is made at the preliminary study stage and ﬁnal control will be realized by combining the various data in the actual
operation phase.

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4.2 Optimal Control of Energy Supply

heat load to be consumed
in the covered facilities.

2 Compute optimal operational
plan against the required
amount of energy.

3 Integrated control of energy

022 0 2 4 6 8 10 12 14 16 18 20Time

Energy amount

1 Predicted power load andEnergy amountFig. 4 shows an outline of the optimal controlof energy supply. First, a demand pattern is predictedbased on the statistically processed data obtained
from actual energy consumption results. Then,based on the combined patterns of CHP operationand the amount of purchased energy from the REP
to meet the predicted energy demand, the system
calculates the operation pattern to produce the minimum environmental cost or energy cost as an operation plan. Based on the obtained operation plan,
integrated control between the receiving power andthe CHP is made to satisfy restrictions such as an
operation prohibited time zone and restrictions on
start-up operation frequency.
In order to realize the integrated control at amore practical level, simply generating control signal output per the operational plan is not enough. It
is required to make a program that can properly
cope with any actual phenomena that may occur inpractical energy management. To be speciﬁc, possible scenarios could include: energy consumptionthat does not result as the demand predicted or thatthe energy equipment which is referred to as anenergy resource, energy storage, and heat source(collectively “energy equipment”) become out of0
22 0 2 4 6 8 10 12 14 16 18 20

producing equipment basedon the operational plan.

amount in response to
the conditions update
operational plan.

Time

Energy amount

4 Correction of the control0
22 0 2 4 6 8 10 12 14 16 18 20

TimeFig. 4order, or that the start/stop operation of energy
equipment may be arbitrarily designated due tomaintenance service. To address such irregularphenomena, the delivered system is devised tomaintain the present control status properly with theuse of two methods, compensation of controlled
variables and operation plan updating.
The above correction on controlled variables isneeded in following up the situation where a dynamic ﬂuctuation has occurred in the power load in ashort amount of time. This is to meet the upper andlower limits of receiving power. These limits are
already deﬁned according to the power purchase
contract and conﬁguration of facilities. Energy management has to be made, therefore, to be within a
pre-set range of a proper controlled amount of energy. In the event that there is a large difference
between demand prediction and an actual situation,
the operational plan will be updated after correcting
the demand prediction or conducting another prediction. If the phenomenon is attributed to changes
in the status of energy equipment, the present energy ﬂow and the conditions of the equipment conﬁguration will also be modiﬁed.
Since the mechanism of above-mentioned
control volume adjustment and operation plan
updating are in a mutually complementary relationship, the design consideration is made to produce
an adequate interlinking operation that will notcause any contradiction in the sequential control. In
addition, the steps from the assessment of conditions to the generation of control signal outputs, are
all fully automated.
Further, it is possible to consider the inﬂuenceof maintenance service in advance by adopting
operational conditions that can compute and produce an arbitrary operation plan against the selected time frame and any related energy equipment.

Outline Optimal Control of Energy Supply

Practical level control is made following the sequence: demand
pattern prediction, computation of operational plan, integrated
control, control volume correction, and operational plan updating.

4.3 Expected Effects
After the start of BEMS system operation,
wide-area internal energy sharing can be maintained among the YCU Medical Center the Minami
Ofﬁce Building and it becomes possible to minimize
environmental and energy costs. The control ismade to meet the daily changing energy demands
and current contract electric bill rates. Further, byupdating the setup conditions, energy management
can be made with due consideration to such factors
as of the effect of changes in the energy unit priceor energy efﬁciencies of the equipment.
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5 Postscript
This paper introduced an example of widearea internal energy sharing maintained among thecustomerʼs multiple facilities by using their in-house
generated energy. Our smart BEMS is adopted inorder to manage and control both energy consumption and supply. Meanwhile, with the deregulationsof electricity market in Japan, it is anticipated thatchoices of power sources will increase remarkably
on both the REP side and energy consumer side.
For this reason, there will be cases when theapproaches of sharing the in-house generated
energy over oneʼs own transmission system or(energy) retail wheeling (process of the delivery of12

MEIDEN REVIEW Series No.169 2017 No.1

energy generated by in-house power generation
unit over its transmission system owned by an electric power company) may be taken into consideration. As such, the importance of Information andCommunication Technology (ICT) will increase. Thesmart BEMS is a typical product that represents the“best use of energy and ICT technology.” We willcontinue to meet such modern-day requirements inthe future.
Lastly, we would like to express our thanks to
many project-related individuals for your kind suggestions and supports for this BEMS system.
・All product and company names mentioned in this paper are
the trademarks and/or service marks of their respective owners.