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18 UEC Int’l Mini-Conference No.52
contain flexibility regions, simulation parame-
ters, or local voltages. As this work focuses on
the vulnerability of the Bus Controller regarding
faulty or falsified upstream signals, only the Bus
Controller is explained in detail. For a complete
understanding, the thesis by Hinners [10] can be
studied.
2.1 Bus Controller
The bus controller objectives are to follow the
reference power flow signals r P and r Q , received
from the SPC-Controller, and to exhibit a bus
controller behavior that is easy to model for sim-
ulations done by higher control and monitoring
entities. From now on in this chapter and all
follwoing chapters, r (reference signal) is used
instead of r P and r Q , if the equations for r p and
r q are identical. The bus controller objectives
can be achieved by a first-order transfer behav-
ior of the bus controller, as it has an analytic
solution. To fulfill the objectives, the following
considerations are made.
The DER dynamics can be assumed to have
a first-order transfer function, and the sum of
Figure 1: Caption
these first-order transfer functions is the bus
controller transfer function (1).
n
area is controllable from the Transmission Sys- X 1
tem Operator (TSO) perspective in a manner y = T i · s + 1 (r i − y i ) (1)
similar to conventional power plants [13]. Fur- i=1
thermore, this geographical area must provide The number of DERs connected to the bus is
the ability to perform real-time simulations by n, and the time constant of the DERs is T i . r i
aggregating all controllable devices into a sin- is the reference signal for each DER and y i is
gle device. The proposed SPC architecture en- the power measurement at the interconnection
ables the coordination of Transmission System point of the DER to the grid at a specific point
Operator-Distribution System Operator interac- in time. This difference is represented as R i in
tions for cross-over voltage level operations [4]. the following. Bringing equation (1) to a single
The cross-over voltage operation considered is numerator, (2) is obtained.
the Interconnection Power Flow (IPF) of both
active and reactive power between the TSO and P n Q n (T j s + 1)
i=1 R i j=1
Distribution System Operator and is one of the y = with i ̸= j (2)
control objectives of the SPC-Level controller, (T 1 s + 1) · · · (T n s + 1)
as well as the voltage/Var control inside the The stability of the system is given, as (2)
SPC. As previously mentioned, the control ar- 1
has n negative poles at s = − and n−1 zeros.
T i
chitecture is distributed over four levels, see Fig- However, temporary undershoots or overshoots
ure 1. Between each level, reference signals are can occur. Assuming (3),
transmitted. The downstream signals contain
the reference power flow or reference power gen- P n R i
i=1
eration information, and the upstream signals y = (T 1 s + 1) · · · (T n s + 1) (3)
