Discussion on Transmission Pricing

1
Discussion on Transmission Pricing
Congestion Management in a Competitive Power
Market
Prof. S.C.Srivastava Department of Electrical
Engineering Indian Institute of Technology Kanpur
2
Major Highlights of Prof. Bialeks Presentation

• Discussed Basic Principles Few Methods of
  Transmission Pricing.
• LMP reflects the cost of transmission losses and
  opportunity costs due to transmission constraints
  (such as line flow constraints during congestion)
• LMP Method quite involved and needs
  simplification for practical applications such as
  using zonal rather than nodal pricing.
• LMP may not recover capital cost completely.
  Methods based on MW-km or TNUoS (Transmission
  Network Use of System in UK) can be used.

3
Few Issues associated with Transmission Pricing
and Congestion Management

• How to form Price Zones?
• Bids of regulating power market are used for
  congestion management. Identification of cluster
  of buses most effective in congestion alleviation
  will minimize number of Gencos/Discos in
  congestion management.
• Role of reactive power readjustment in congestion
  management.
• Allocation of transmission loss make up and
  congestion cost amongst market participants.

4
A Nodal Price Based Bus Clustering and Network
Reduction Technique(by H.K. Singh S.C.
Srivastava, IEEE PES GM, San Fransisco,12-16 June
2005)

• Criteria
• Nodes in a group must have relatively close
  marginal prices, and should be geographically
  close to each other.
• For a change in system loading, the differential
  marginal prices must be relatively close,
• Steps
• OPF performed on full system and real power
  marginal prices (MP) are computed.
• Overall system load is increased by 5 and MP
  computed using OPF. Differential marginal prices
  are calculated.
• Initial node grouping is done based on marginal
  prices.
• Groups are fragmented considering differential
  prices.
• Groups are further modified considering
  geographical proximity.
• Groups are reduced to equivalent nodes using REI
  reduction technique

5
Group formation for an Indian system
6
Average marginal prices of groupsand at
theirequivalent nodes
7
Cluster/Zonal Based Congestion Management Using
Real and Reactive Power Rescheduling(Ashwani
Kumar, SC Srivastava and SN Singh, A Zonal
Congestion Management Approach Using Real and
Reactive Power Rescheduling, IEEE Trans. on
Power Systems, Vol.19,No.1, Feb.2004, pp.
554-562.)

• The congestion cluster based congestion
  management approach utilizing both real and
  reactive power rescheduling is presented.

• Two sets of sensitivity indices have been
  proposed
• Real power transmission congestion distribution
  factors (PTCDFs) Reactive power transmission
  congestion distribution factors (QTCDFs)

• The most sensitive clusters/zones are obtained
  as
• The union of most sensitive zones obtained on the
  basis of PTCDFs and QTCDFs

8
Congestion Clusters based on PTCDF for 39-bus
system(Line34-14)
9
Congestion Clusters based on QTCDF for 39-bus
system(Line 34-14)
10
Combined Congestion Clusters for 39-bus System
11
Congestion Cost Allocation Using a Unified Power
Flow Tracing Approach(H.K.SinghNetwork
Reduction, Congestion Management and Transaction
Allocation Algorithms in Electricity Market,
Ph.D. Thesis,IIT Kanpur, August 2004.)

• Conventionally MW flow and MVR flow are traced
  separately
• A new unified method suggested to trace the
  apparent power flow
• A complex set of distribution factors defined for
  MVA flow tracing, based on Proportional sharing
  principle. This involves

• Line flows obtained from base load flow
• Lossless real and reactive power flow networks
  formed separately
• Two networks are combined and modified.
  Fictitious lines and buses added.

12
Tracing Methods Using Proportional sharing
principle (Work by Bialek)

• Determination of shares of inflows in terms of
  outflows and outflows in terms of inflows

Inflows
Outflows
13
Power tracing algorithm
Inflow to node i from line i-j can be
calculated using Proportional sharing principle
as,
14
Power tracing

• Constraint Sending end power Receiving end
  power

AC power flow on 4 node network
15
Real power tracing
Make the system lossless
Lossless real power flow
16
Reactive power tracing
Making a lossless reactive power system
Lossless reactive power flow with fictitious nodes
17
Network modification for flow direction uniqueness
Case 1 Pij Qij same direction Pji Qji same
direction
Case 2 Pij Qij same direction Pji Qji
opposite direction
18
Case 3 Pij Qij opposite direction Pji Qji
same direction
Case 4 Pij Qij opposite direction Pji Qji
opposite direction
19
Demonstration on 4 node system
20
Transmission Pricing Congestion Management in
India

• Indian power sector has five REBs SEBs. As part
  of reforms process, vertical unbundling in
  several states have taken place and number of
  Discoms have been formed.
• Centralized Dispatching through RLDCs and SLDCs.
  States get power from Central Generating units as
  per their entitlement. Frequency Linked ABT in
  force at the regional level.
• Congestion management is the responsibilities of
  RLDCs and SLDCs.
• Electricity Act 2003 stipulates introducing
  competition at different levels and open access
  to transmission Distribution wires.
• Zonal Postage Stamp Method for Transmission
  Pricing. Zones divided based on distance traveled
  (1 stamp for every 100km).
• Issues related to charges for congestion has to
  be worked out.